- Email: [email protected]
Instability after major tumor resection
INSTABILITY AFTER MAJOR JOINT REPLACEMENT
0030-5898/01 $15.00
+
.OO
INSTABILITY AFTER MAJOR TUMOR RESECTION Prevention and Treatment Craig H. Gerrand, MB, ChB, Robert S. Bell, MD, MSc, FRCSC, Anthony M. Griffin, BSc, and Jay S. Wunder, MD, MSc, FRCSC
Limb-sparing surgery has become accepted as standard surgical treatment for primary bone sarcoma.s,10,24,46, 51, 52 Most bone resections involve joints, and the resection of periarticular muscle, ligament, and tendon to achieve a negative margin is not conducive to a stable reconstruction. Instability adds morbidity to a procedure, reduces functional outcome, and may lead ultimately to failure of the reconstru~tion.~~ This article discusses reconstructive techniques in the pelvis and lower limb with particular emphasis on the problem of instability, including instability of the pelvis. Stability is defined as the ability of the reconstruction to withstand physiologic loading, rather than simply avoiding dislocation. This definition is particularly significant when discussing stability in the pelvis. PELVIC RESECTION Improved imaging techniques and neoadjuvant therapies have increased the number of limb-sparing procedures performed for malignant pelvic tumors. Local and systemic relapse rates remain high, however.2,5, la,45, 46, 55, 58 Limb Supported by The Wishbone Trust, Ethicon, Depuy UK, and Stryker Howmedica (CHG).
salvage is appropriate when a satisfactory surgical margin can be obtained or when an amputation cannot provide a better surgical margin. For the purposes of this discussion, instability of the pelvis is defined as loss of osseous continuity between the femur and the ipsilatera1sacrum. Pelvic stability may be maintained after resection of the anterior pelvis or incomplete resection of the ilium, which maintains the arch of the sciatic notch. Complete resection of the ilium may require reconstruction, however, and periacetabular resections are particularly challenging.2,5, la,45,55, 58 After pelvic resection, the decision to reconstruct and the mode of reconstruction are influencedby many factors, including the condition of the patient at surgery, the prognosis, the functional demands of the patient, the extent of the resection, and the availability of implants and allografts. Proponents of anatomic reconstruction believe that it is important to restore the bony anatomy and mechanical stability of the pelvis. Given the significant complication rates associated with pelvic reconstruction, however, resection without reconstruction may be reasonable in certain circumstance^.^^ OConnor and Sim4'jfound that the pelvis became unstable after 37 of 60 resections (62%). When the pelvis remained stable, the average
From the University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto, Ontario, Canada (CHG, RSB, AMG, JSW); and the Department of Orthopaedics, University of Glasgow, Glasgow, United Kingdom (CHG)
ORTHOPEDIC CLINICS OF NORTH AMERICA VOLUME 32 * NUMBER 4 * OCTOBER 2001
697
698
G E R U N D et a1
functional score using the modified Musculoskeletal Tumour Society (MSTS) system (1987) was 33 out of a total 35 points. When the resection resulted in instability but stability was restored by reconstruction,the average MSTS score was 28 points. When stability was not restored, the average MSTS score was only 15 points.
Iliac Resection After resection of the ilium, reconstruction may be anatomic (the hip joint is restored to its normal level, and the pelvic ring is reconstituted) or nonanatomic (the iliac stump is approximated to the sacrum). Many reconstructive techniques have been described, including primary arthrodesis with wires and bone grafting with vascularized or nonvascularized autografts, allografts, or custom implants, but all of these techniques have a significant complication rate.2,s, 34, 36, 46, ss, 58 Nonanatomic reconstructionmay lead to limblength inequality, sciatic or obturator nerve entrapment, and ultimately scoliosis and back pain. If no reconstruction is performed, a large abdominal hernia and painful pseudarthrosis may r e ~ u l t . ~ Campanacci and Capanna7 reported the results of 32 sacroiliac resections. In 15 cases, the iliac resection was subtotal, and pelvic stability was maintained. Functional results were excellent in 10 cases, good in 4, and fair in 1. Three of 6 patients who had complete iliac resection without reconstructionhad satisfactory outcomes compared with 3 of 4 patients who had reconstruction using intercalary allografts. Campanacci and Capanna7 recommended reconstruction of the pelvic ring. OConnor and Sim46reported 17 sacroiliac resections. In 7 cases, resection was above the level of the sciatic notch, the pelvis remained stable, and functional results were excellent in 6 and good in 1. In 5 cases with a successful iliosacral arthrodesis, results were excellent in 3 and good in 2. Of 2 cases with a pseudarthrosis, results were fair in 1 case and poor in the other. No attempt at reconstruction was made in 3 cases, and the results were good in 1, fair in 1, and poor in 1. OConnor and Sim46 implied that reconstruction should be done if possible. Ozaki et a147described 12 patients who had iliac resection and iliosacral arthrodesis using allograft. The grafts were fixed with large cancellous screws, which loosened in 3 patients. There were 2 deep infections, 1 fracture, and
1 nonunion. Functional scores for 10 patients with grafts in situ were excellent in 3, good in 6, and fair in 1. There was no comparison in this series with other methods of treatment. Porsch et a148described 6 patients who had iliac resection for Ewing’s sarcoma and reconstruction with autograft. One patient did not undergo reconstruction and developed pelvic instability and pain, which were alleviated by late reconstruction with a vascularized fibular graft. Porsch et a148believed that outcome was related to pelvic stability and that reconstruction of the defect would improve functional results. Thomas et a154reported on 3 complete iliac resections for Ewing’s sarcoma. Two were reconstructed with Steinmann pins and autogenous bone graft. Reconstruction reduced but did not prevent limb shortening, and all patients had some degree of pelvic instability. The patient who did not undergo reconstruction had a poor functional result. Thomas et a154favored reconstruction. Authors’ Preferred Approach. If iliac resection is subtotal and the sacroiliac joint is not involved, there is no requirement for reconstruction. The authors do not attempt to fill, the defect. If the resection involves the sacroiliac joint, there is the potential for instability. The authors recommend fusion with interfragmentary cancellous screws if the residual ilium and sacrum can be approximated adequately (Fig. 1). The authors do not reconstruct the pelvis routinely after complete iliosacral resection. The authors reviewed 13 patients who underwent iliosacral resection. Four patients underwent reconstruction, and 9 did not. The groups had similar functional outcomes and general health status measures, but the reconstructed group had a significantly higher complication rate, increased blood loss at surgery,and longer hospitalization. None of the patients without reconstruction have had sciatic nerve symptoms (Fig. 2).
Periacetabular Resections Reconstruction of the hip after resection of the acetabulum is challenging. Among the techniques described are endoprosthetic replacement, saddle prosthesis, allograftprosthesis composites, arthrodesis and surgical pseudarthrosis.’,13, 34, 35, 47, 58 The complication rates of all techniques are significant. Instability of the hip joint as well as the pelvis may be a problem.
INSTABILITY AFTER MAJOR TUMOR RESECTION
699
Uchida et a155described a constrained implant, with a cup fixed into the remaining ilium or sacrum with cement and screws and a long cemented femoral stem. In a series of 18 patients with primary and metastatic tumors in the acetabular region, 2 had dislocations after a fall requiring revision of the implant. Saddle Prosthesis
Figure 1. This 34-year-old woman underwent iliosacral resection for chondrosarcoma. The residual sacroiliac joint was fused with cancellous screws and has united.
Endoprostheses Endoprosthetic reconstruction of the pelvis is associated with significant rates of infection and dislocation. Matching the implant to the recipient is difficult, and most implants are custom-made.2,16,44,55, 58 Abudu et a12 described the use of a custom-made titanium implant with a polyethylene cup, articulating with a conventional Stanmore femoral prosthesis with a 32-mm head. The implants were fixed with pins and cement into the residual ilium. In a series of 35 patients, 9 (26%) developed a deep infection. Six patients (17%) developed recurrent dislocation treated by closed reduction and physiotherapy and, in 1 case, by revision of the cup. Two implants loosened but subsided into a stable position. Windhager et a158 described a customized implant manufactured from a three-dimensional model of the pelvis on which the extent of the tumor and the planned resection margins were marked. Postoperatively the patients were placed in a plaster cast for 6 weeks and a hip brace for 4 to 6 months. Functional results of 5 patients with more than 12 months’ follow-up revealed that all had a positive Trendelenburg sign. There was 1 hip dislocation and 1 deep infection.
Although the saddle prosthesis was designed for hip reconstruction after failed arthroplasty and acetabular bone loss, it may be used after periacetabular resection for tumor, despite the potential problems of a large residual dead space and a nonanatomic hip center.’,’3,58 The saddle articulates with a notch cut in the remaining ilium. If the ilium has been resected completely, it may be possible to construct an articulation using allograft or cement fixed to the sacrum.’ Stability of the reconstruction depends heavily on soft tissue tension, and reconstruction may be contraindicated in cases in which the abductor or iliopsoas muscles have been resected. Aboulafia et al’ described their experience of the saddle prosthesis in 17 patients, 8 with primary malignancies and 9 with metastatic disease involving the pelvis. Patients received 2 to 4 weeks of traction postoperatively and 6 to 12 weeks of bracing. There were 2 prosthetic dissociations and 2 dislocations.’ Windhager
Figure 2. This 32-year-old woman had a sacroiliac resection for Ewing’s sarcoma. The defect was not reconstructed and a stable pseudarthrosis developed. She walks well with a cane and a shoe lift.
700
G E R U N D et a1
et a15' reported functional results in 4 patients after periacetabular resection. Function was good in 1 case, fair in 2, and poor in 1. Of 5 patients who had endoprosthetic reconstruction, function was good in 3, fair in 1, and poor in 1. Windhager et a158concluded that functional outcome was better after reconstruction with a custom implant.
Allograft-Implant Composite The advantages of using an allograft for reconstruction of the pelvis include healing to and partial replacement by host bone and the ability to shape the allograft to fit the defect at the time of surgery and soft tissue attachments. Disadvantages include a high infection rate, the risk of viral transmission, and allograft fracture, which may lead to pelvic i n ~ t a b i l i t y . Ozaki ~ ~ , ~ ~et a147 described 9 patients who underwent reconstruction with an allograft, a cemented acetabular cup, and a cementless femoral component. There were 5 infections and 1 allograft fracture. Ozaki et a147concluded that the complicationrate was unacceptable. 4 cases usLanglais and V i e l p e a ~described ~~ ing allografts and a standard cemented total hip prosthesis. Three braided polypropylene ligaments were used to stabilize the hip. One was placed transversely across the neck of the femoral implant to prevent upward subluxation, one was placed anteriorly to limit external rotation, and one was placed posteriorly to limit internal rotation. The rim of the iliac crest with its soft tissue attachments was preserved and attached to the graft. There were no dislocations and no infections.
thesis resulting in painless pseudarthrosis. Capanna et a19preferred ischiofemoral arthrodesis when the inferior and medial acetabulum had been retained, but noted that the pelvis may tilt, hinging on the pubic symphysis and causing scoliosis, unless the pelvic ring was reconstituted. Of 14 attempted iliofemoral arthrodeses, OConnor and Sim46reported 6 successful fusions, 4 stable pseudarthroses, and 4 failures. In 2 cases, an intercalary allograft was used to restore length to the leg or to allow fusion to the sacrum. Both allografts became infected, and a flail limb was the end result. Ischiofemoral arthrodesis was attempted in 3 cases; the arthrodesis was successful in 1case, resulted in a stable pseudarthrosis in 1case, and was followed by amputation for recurrence in 1 case. One attempt at ischiofemoralpseudarthrosis resulted in a stable femorosacral pseudarthrosis. Functional outcome was better when a stable arthrodesis had been achieved.46 Authors' Preferred Approach. If the femoral head can be preserved despite acetabular resection and it is possible to avoid shortening the limb by more than 5 or 6 cm, iliofemoral arthrodesis is performed. Despite the loss of leg length, the durability of this physiologic reconstruction is appealing when union has been achieved (Fig. 3).
Arthrodesis If there is sufficientbone stock, continuity between the pelvis and femur may be restored by iliofemoral or ischiofemoral arthrodesis. The major advantage of this approach is that it provides a stable and durable reconstruction. Disadvantages include leg shortening, lack of hip mobility, and long consolidation times. Arthrodesis may be difficult to achievebecause of the small contact area, the long lever of the lower limb acting through the arthrodesis site, and the fact that the local blood supply may be compromised by surgery and radiotherapy. Capanna et a19 could achieve iliofemoral arthrodesis in only 50% of cases and suggested that the goal of treatment should be iliofemoral coaptation with minimal osteosyn-
Figure 3.This 17-year-old patient presented with Ewing's tumour of the left hemipelvis. His original arthrodesis was revised twice before solid fusion was achieved.
INSTABILITY AFTER MAJOR TUMOR RESECTION
After more extensive periacetabular resection (especially if the femoral head cannot be salvaged), the authors' preference for reconstruction depends on the extent of remaining ilium. Previously the authors performed reconstruction in almost all patients with an allograft-implant composite, but if there is sufficient bone stock, presently the authors prefer to use a saddle prosthesis. The saddle prosthesis enhances the stability of the construct with a Dacron aortic vascular graft passed over the iliac crest or through a small window in the upper ilium and sutured under tension to the implant. The authors had 1 case in which, despite the graft, the saddle dislocated when the patient fell heavily during a period of postoperative confusion (Fig. 4). If it is necessary to resect the acetabulum and the ilium as far posteriorly as the sacroiliac joint (or through the sacral ala), an allograft is used, always in conjunction with a total hip arthroplasty. The allograft is shaped to fit the defect and held to host bone with long cancellous screws with or without additional neutralization plates. Before implantation, the allograft is prepared to accept a cemented cup, and care is taken to place it in a horizontal position (Figs. 5 and 6 ) . If the hip is grossly unstable and the capsule cannot be reconstituted using host and allograft soft tissues, it can be augmented with hhrlex or Dacron (Fig. 7). In a series of 10 patients reconstructed with an allograft-implant composite, there were 4 dislocations. Three dislocations stabilized
Figure4. This 61-year-old man had a periacetabular resection for chondrosarcoma. A saddle prosthesis was used for the reconstruction but dislocated after a fall.
701
Figure5. This 56-year-old man underwent pelvic resection for high grade leiomyosarcoma and reconstruction with a hemipelvic allograft and cemented total hip arthroplasty. At 4-year follow-up, the graft has united to the sacrum. The patient used two canes for walking.
Figure 6. This 32-year-old woman had a pelvic chondrosarcoma treated by resection and reconstruction with a hemipelvic allograft secured with neutralization plates. At 10-year follow-up, the allograft has united and the patient has excellent function.
702
GERRAND et a1
Figure 7. A, After resection of the femur, a sheet of Marlex mesh is sutured to the capsular remnant using a nonabsorbablesuture. 6,The mesh is tightly wrapped around the neck of the prosthesis and sutured to itself to create a new hip capsule. C, The prosthesis within the tube of mesh has been sutured into position. (From Masterson EL, Ferracini R, Griffin AM, et al: Capsular replacement with synthetic mesh. J. Arthroplasty 13:860-866, 1998; with permission).
spontaneously after closed reduction. One required trochanteric advancement to achieve stability. In 2 cases, the limb deliberately was lengthened 3 cm to increase the soft tissue tension. Both cases had partial sciaticnerve palsies that recovered slowly.1s In a series of 17 patients managed with a pelvic allograft with a minimum 4-year followup, 3 patients died of metastatic disease, 3 had local recurrence, and 2 had deep infection of the allograft. Two patients were managed as an osteoarticular reconstruction but had unsatisfactory outcomes; 1 patient had local recurrence, and the other was revised to an allograft-implant composite. Allograftimplant reconstruction rather than osteoarticular allograft reconstruction is appropriate in this situation. Eight patients were alive with their original allograft in situ; 7 had MSTS (1993) functional scores averaging 72%; the other patient had chronic subluxation of the hip and a poor r e ~ u l t . ~
lschiopubic Resection Because it does not involve interruption of continuity between the femur and the sacrum, resection of the anterior pelvis alone is not associated with instability, reconstruction usually is not required, and functional results are good. Campanacci and Capanna7reported 11 excellent, 2 good, and 3 fair results in 16 ischiopubic resections. OConnor and Sim46reported 10 excellent and 1good functional result in 11 cases. Occasionally, resection of the anterior pelvis may involve the acetabulum. If the superior portion of thh acetabulum can be maintained, careful capsular repair and postoperative bracing may result in a stable hip.31Some workers suggest the use of Steinmann pins to maintain reduction during soft tissue healing7 Authors’ Preferred Approach. It is not the authors’ practice to reconstruct the bone defect after anterior pelvic resection. The authors use
INSTABILITY AFTER MAJOR TUMOR RESECTION
a pedicled fascia lata rotation flap to close the soft tissues at the front of the pelvis. If the resection involves the inferior part of the hip joint, care is taken to repair the capsule at the end of the procedure, and postoperatively a brace is used. If the hip remains unstable, the authors’ preferred reconstruction is arthrodesis. PROXIMAL FEMUR
The proximal femur is a common site for primary bone sarcoma, especially chondrosarcoma. Local anatomy allows most tumors to be managed with limb-sparing surgery because important neurovascular structures usually are not involved. If the hip joint is spared, an intraarticular resection is adequate. If there is suspicion that the hip is involved, a more radical resection may be required involving the periarticular soft tissues, which makes stable reconstruction more difficult. If there is gross contamination of the hip joint, it may be necessary to perform a true extra-articular resection, including acetabulum. The 2 factors crucial to determining stability after reconstruction of a proximal femoral tumor are (1) whether it is necessary to resect capsule and the proximal muscles that attach the femur to the pelvis (external rotators, iliopsoas, proximal adductors) and (2) whether it is possible to reconstruct the trochanter and abductor attachment. Options for reconstruction include endoprosthetic replacement, allograft-prosthesis composites, osteoarticular allografts, and arthrodesis. Each presents particular issues related to stability. Endoprostheses
The major advantage of endoprosthetic reconstruction is that it allows immediate or early joint motion and weight bearing. This advantage may be particularly important when adjuvant chemotherapy is planned or if life expectancy is limited. In the largest reported series, the probability of surviving aseptic loosening of a cemented proximal femoral prosthesis was 94% at 10 years.56Joint instability is a major concern, with dislocation rates of 3% to 36% r e p ~ r t e d . ” , Malkani ~ ~ , ~ ~ et aP8 reported dislocation in 11 of 50 patients who underwent proximal femoral replacement for nonneoplastic disorders and found a relationship with multiple previous procedures and abductor insufficiency. Dislocation rates are thought to be lower when a bipolar head is
703
used and when the abductors are reconstructed adequately8,20,59 Most authors emphasize the importance of careful capsular repair. Kabukcuoglu et aBO reported the results of 54 proximal femoral replacements using custom-made femoral implants with a 29-mm or 32-mm head and a cemented polyethylene cup. The mean follow-up time was 9 years. There were 6 dislocations. Four of these stabilized after closed reduction and rehabilitation, and 2 were revised. Morris et a142reported 31 proximal femoral replacements using the Kotz (Howmedica Modular Resection System, Howmedica, Rutherford, NJ) modular replacement system. In 29 cases, a bipolar head was used. There was 1dislocation of a bipolar prosthesis and 1 deep infection. Haentjens et all9 reviewed 28 patients with metastatic disease. If the acetabulum was involved, a total hip arthroplasty was performed. If the acetabulum was spared, a bipolar head was used. There were 4 dislocations in 11 patients in the total hip arthroplasty group and none in the bipolar group. Allograft-Implant Composites
Allograft-implant composites offer biologic reconstruction that restores bone stock and allows load sharing with the prosthesis. Enhanced soft tissue reconstruction may improve implant stability.61Disadvantages include fracture, infection, nonunion, graft resorption, and risk of viral disease transmission. Jofe et alZ9reported medium-term results in 13 patients. Jofe et alZ9emphasized the need for careful soft tissue repair of the capsule and abductors. There were no dislocations, 2 allograft fractures, and 1 infection. Nine Austin Moore hemiarthroplasties, 3 of which subsequently were revised for pain; 2 bipolar prostheses; and 2 total hip arthroplasties were used. Jofe et alZ9believed that these results were better than those obtained by osteoarticular allograft. Harris et alZ2 reported the results of 11 patients who had allograft-prosthesis composite reconstruction of the proximal femur after resection for tumor. There were 5 nonunions but no dislocations. Zehr et a16’ compared the outcomes and complication rates of allograft-prosthesiscomposites and endoprostheses in the reconstruction of the proximal femur. There was at least 1 episode of instability in 5 of 18 endoprosthetic reconstructions but none of 18 composite reconstructions. Four of the unstable
704
GERRAND et a1
reconstructions had a total hip arthroplasty rather than a bipolar hemiarthroplasty. Osteoarticular Allografts
Several authors reported the use of osteoarticular allografts to replace the proximal femur. Matching the sizes of the graft and host acetabulum preoperatively is difficult, and the surgeon may need to proceed to an allograftprosthesis composite if the fit is unsatisfactory. The allograft requires a long rehabilitation period with protected weight bearing. In the longer term, there are reports of joint colla se and cartilage fragmentati~n.~~ Jofe et a1 reported 15 cases in which the proximal femur was replaced by an osteoarticular allograft. There were 4 infections, 3 fractures, 2 nonunions, and 1unstable hip.29 Authors’ Preferred Approach. In general, the authors prefer the use of a modular femoral endoprosthesiswith a bipolar head, although this does not guarantee against dislocation (Fig. 8). If the articular cartilage of the acetabulum is in poor condition, acetabular resection has been performed, or the patient’s acetabulum is too small for the smallest available implant, a cemented polyethylene cup is used. The greater trochanter is osteotomized and reattached to the implant if possible. Reattaching the trochanter to a bone ingrowth surface results in improved abductor function (Fig. 9). If the greater trochanter cannot be preserved, the abductor tendon is attached to
P
Figure 8. This 24-year-old woman had resection of the proximal femur for Ewing’s sarcoma. Her acetabulum was too small for the smallest available bipolar implant and therefore a cemented cup was used. Despite capsular reconstruction she went on to experience recurrent dislocation.
Figure 9. This 18-year-old woman had total femoral resection for osteosarcoma. The greater trochanter is firmly reattached to the bone ingrowth surface on the implant. The patient had grade 4 abductor power.
the implant or the surrounding soft tissues. The hip joint capsule usually is resected with the proximal femur, although the labrum is maintained. Stability of the reconstruction is assessed on the operating table, after optimizing implant alignment and limb length. If the hip remains unstable despite these measures, the capsule can be reinforced with synthetic mesh attached to the labrum or with bone sutures to the acetabulum (see Fig. 7). The authors reviewed their experience of capsular replacement in 13cases after proximal femoral reconstruction. None of 4 patients who had a bipolar articulation and capsular replacement experienced dislocation compared with 4 of 9 who had a total hip arthroplasty. All patients in this series had extremely unstable implants after resection of
INSTABILITY AFTER MAJOR TUMOR RESECTION
all muscles surrounding the hip and the hip capsule.39 In the authors' experience of allograftimplant composites, the functional results were disappointing. Although the abductor tendon could be attached to the allograft soft tissues, this did not translate into better abductor function. When the host greater trochanter was attached with wires onto allograft, however, abductor function was improved.40The authors reserve the use of an allograft-prosthesis composite for cases in which the greater trochanter can be preserved, and the level of the osteotomy is such that it can be bridged by a long-stemmed hip prosthesis. DISTAL FEMUR The distal femur is the most common site for primary bone tumors. An osteoarticular allograft may be considered in cases in which resection is intra-articular and the opposite joint surface and joint motors can be preserved. This approach may be particularly useful in a growing child. Reconstructive options after extra-articular resection include endoprostheses, osteochondral allografts, and allograft-prosthesis composite^.'^ In considering stability of a reconstructive procedure for the distal femur, it is necessary to assess translational and angular stability of the femorotibial joint as well as the congruity of the patellofemoral articulation. Endoprostheses
After resection of the distal femur, an endoprosthesishas the advantage of restoring stability immediately. Most implants have a degree of constraint in their design that imparts stability without depending on soft tissue stabilizers, many of which may have been excised. Most implants incorporate a degree of hyperextension, which allows a patient with a weak extensor mechanism to lock the knee in full extension and enhances the stance phase of gait.32Implant failure rates are increased in the presence 32, 56 of extensive bone and soft tissue re~ection.~, Although a direct comparison between studies is difficult, more constrained implants may be associated with early failure. Unwin et a156reported results of 493 distal femoral replacements with a custom implant based on a fully constrained knee. The probability of surviving aseptic loosening was
705
reported as 67% at 10 years. In a series of 40 patients, Kawai et aP2 reported survival of a semiconstrained knee as 85%,67%,and 48% at 3, 5, and 10 years. Capanna et a19 reported results of the uncemented Kotz modular tumor reconstruction system in 95 patients. This system has a simple hinge articulation based on a metal axle within a polyethylene bushing. The bushing failed in 42% of cases at a mean of 64 months postoperatively and was the most common reason for revision. Bushing failure produces mild coronal instability, although this is p a i n l e ~ s .Bushings ~,~~ for this prosthesis have been redesigned and markedly improved. Horowitz et alZ6reported 59%5-year event-free prosthetic survival for a constrained design. Rotating hinge designs have the theoretic advantage of providing stability and reducing stress transfer across the knee by permitting flexion and extension, rotation, and axial translation. Malawer and ch01.1~~ reported revisions of 3 of 31 distal femoral replacements at a mean of 3.5 years. Of these, 27 were rotating hinge designs. Choong et al" reported results in 30 patients treated with an implant based on a kinematic rotating hinge. There were 2 failures in 32 implants at 5 years. Eckhardt et all4 reported results of 52 distal femoral replacements with a rotating hinge knee. Four were revised for mechanical complications at a median of 44 months. Few authors commented on patellar instability or anterior knee pain after prosthetic reconstruction of the distal femur. Most tumor prostheses have deep, constrained patellar grooves, which likely compensate for the extensive soft tissue resections necessary for tumor resection. Osteochondral Allograft
Immediate stability of a reconstruction using an osteochondral allograft depends on sound soft tissue repair, the correct size of allograft, and graft fixation. Primary repair or reconstruction of the cruciate ligaments and patellar tendon are i m p ~ r t a n t . ' ~ Late , ~ ~instability follows failure of the soft tissue reconstruction or allograft collapse and may lead to subluxation I2f4l and degenerative arthriti~.~, Mnaymneh et al4I reviewed 96 patients who had reconstruction of the distal femur with an osteochondral allograft. Six (7%)patients had knee joint instability caused by ligamentous laxity and used a brace or crutches. Mnaymneh et a141 suggested this was secondary to
706
GERRAND et a1
inadequate soft tissue repair or anatomicincongruity and emphasized the need for anterior ceciate reconstruction, using semitendinosus or Achilles tendon allograft. Three of the 6 patients had associated complications of fracture, arthritis, and non~nion.~' In a series of 11 patients reported by Gebhardt et al,15 only 1 had an unstable joint. Aho et aP reported results of 11 patients with a mixture of benign and malignant conditions. Functional results were good or excellent in 7, fair in 1, and a failure in 3. Zatsepin and Burdygin60 reported longterm results in 88 patients. The allograft was fixed to the host with a step osteotomy. Of 76 patients for whom results were known, 37 walked without aids, 22 used a cane, and 17 had fractures requiring a crutch or conversion to an endoprosthesis. Zatsepin and BurdygidO noted a progressive reduction in knee movement with time and ultimately deformity and arthritic change. Treatment of instability around the knee usually involves custom bracing or total joint arthroplasty. The osteochondral allograft has the advantage that if revision to an arthroplasty is required and the allograft has healed, bone stock is r e s t ~ r e d . ~ , ' ~ , ' ~
a variable period. The authors routinely assess coronal instability at review appointments and exchange bushings when necessary. This problem has been resolved since the bushing design was revised substantially. The authors prospectively compared functional outcomes and health status data after 31 Kotz fixed-hinge, uncemented, distal femoral replacements with 25 cemented rotatinghinge tumor replacement prostheses (Howmedica Modular Resection System).At a mean follow-up of almost 3 years, functional scores were significantly better in the rotating-hinge group The authors continue to use the fixed hinge with an enhanced bearing, however, to avoid the use of cement in these young patients. Fresh osteochondral allografts have the theoretic advantage of providing an articular surface with viable chondrocytes. A major disadvantage is the time it takes to find a suitable donor, making this technique unsuitable for most malignant lesions. The authors studied fresh osteochondral allograft reconstruction at the knee in the reconstruction of advanced giTen ant cell tumors in 16 patients (Fig. reconstructions were of the distal femur, and 6 were of the proximal tibia. Two grafts were revised for unstable fractures of the distal
Allograft-Implant Composites
There are few reported results of reconstruction using allograft-implant composites in the literature. Harris et alZ reviewed 9 reconstructions using a kinematic rotating hinge or a total condylar revision prosthesis. Complications included 1 patellar subluxation, but there were no dislocations. Hejna and GitelisZ3suggested that the constraint of the implant used should reflect the degree of soft tissue resection.If a significant amount of quadriceps muscle has been resected, a constrained device, such as a fixed hinge or rotating hinge, is required. In cases with minimal resection, a less constrained device, such as a constrained condylar knee, may be more suitable. Authors' Preferred Approach. After resection of the distal femur, the authors prefer endoprosthetic replacement with a cementless stem and use the Kotz modular system. The authors do not insert locking screws routinely to reduce stress shielding and have not found primary stability of the implant to be compromised'33The most significant problem the authors have experienced is failure of the fixed-hinge bushing mechanism after
Figure 10. This patient had a giant cell tumour of the distal femur treated by surgical resection and reconstruction with a fresh osteochondral allograft that has united to host bone.
INSTABILITY AITER MAJOR TUMOR RESECTION
femur. One was converted to a total knee arthroplasty with maintenance of the allograft after a femoral condyle fracture, and there was 1deep infection. Coronal instability was found in all but 1 of 13 patients at long-term review. This patient had an excellent functional result. All of the patients with fair and poor results had significant joint instability often requiring the use of a brace. The authors no longer use osteoarticular allografts for reconstruction of tumors at the knee.
707
58% at 10 years and that the risk was increased with the amount of tibia resected. Horowitz et a127described 16 patients, all of whom had an extra-articular resection of the knee, followed for 2 to 10 years. All the implants were a constrained ball-and-socket design. The patella was screwed to the endoprosthesis to restore extensor function. There were 2 infections, and 3 components became loose in the first 33 months. Allograft-Implant Composites
PROXIMAL TIBIA
Reconstruction of the proximal tibia presents a particular challenge because of the need to reattach the patellar tendon, obtain adequate soft tissue cover, and preserve the neurovascular structures, which are extremely close to bone in this area. Available surgical options include arthrodesis by one of several methods, rotationplasty, and amputation. Salvage of the knee joint is a major advantage in functional terms, but resection of soft tissues around the knee leaves the potential for instability.
The use of an allograft-implant composite facilitates reconstruction of the patellar tendon. The bulk of the allograft makes it essential, however, to provide cover with a gastrocnemius flap. A long-stemmed implant may bridge the junction between allograft and host. Alternatively a short-stemmed implant can be used if the allograft is plated to the host. The choice of implant is determined by the amount of soft tissue resection and the constraint required.23 Osteochondral Allograft
Endoprostheses
Most proximal tibial implants are modifications of constrained total knee arthroplasty designs to compensate for the loss of stabilizing soft tissues. Difficulties encountered include a high infection and loosening rate and problems with attaching the patellar tendon to the implant. The fact that most endoprostheses are significantly less bulky than the resected proximal tibia is a major advantage. Grimer et all7 reviewed their experience of 151 custom-made endoprostheses. The first 95 prostheses were based on a fixed hinge, and the following 56 prostheses were based on a rotating-hinge knee. All were cemented. Initially the patellar tendon was reconstructed with a synthetic braided ligament passed through holes in the implant. This reconstruction caused local irritation and eventually failed, and now the tendon is repaired directly to the gastrocnemius flap. The infection rate was reduced from 36% to 12% by the introduction of routine gastrocnemius flap cover. Grimer et all7suggested that the rotating hinge has a lower failure rate than the simple hinge but could not draw firm conclusions. In a review of 245 replacements, Unwin et a156noted that the probability of a proximal tibial endoprosthesis surviving aseptic loosening was
As in the distal femur, stability of the knee depends on accurate and secure soft tissue reconstruction at surgery, including the posterior capsule, collateral ligaments, patellar tendon, and retinaculum. Some workers routinely repair or reconstruct the cruciate ligaments using allograft tendon, but others do not.6,12,25 Late instability can follow subchondral collapse. Insensitivity of the joint contributes to this instability.6 Clohisy and Mankin12reported the outcomes of 16 osteoarticular reconstructions of the proximal tibia. One patient with a peripheral neuropathy and allograft fracture had an unstable reconstruction and had to undergo amputation. At 7 years’ follow-up, 7 of 16 allografts had not survived, and the most common complicationwas structural failure of the graft. Hornicek et alB reported instabilityin 5 of 38 patients treated with a proximal tibial allograft by bracing or total knee arthroplasty. Brien et a16 compared 17 allograft reconstructions with a historical series of endoprosthetic reconstructions. Of reconstructions, 8 were osteochondral, and 7 were intercalary allografts. Brien et a16found a high rate of complications with both techniques but did not favor either. These workers reported that mild instability is common, despite extensive soft tissue repair at surgery.
708
GERRAND et a1
Authors' Preferred Approach. After resection of the proximal tibia, the authors use an endoprosthesisbecause of its smaller bulk. The authors routinely use a medial gastrocnemius flap. The patellar tendon is fixed to the implant using a polyethylene clamp and is sutured into the flap. On occasion, the authors have been able to preserve the anterior tibia and the insertion of the patellar tendon (Fig. 11). PATELLOFEMORAL JOINT There is considerable potential for patellar problems after resections around the knee. Soft tissue resection may lead to maltracking,
devascularization, and denervation of the patella. Although some workers always resurface the patella, most do not unless the articular surface has been excised as part of the procedure?, 14,37 Patellar replacement has a significant complication rate and does not appear to influence the functional score." It may be important to maintain the height of the patella in relation to the knee joint, especially after a proximal tibial allograft? There are few reports of patellofemoral instability in the literature, but it has been described after reconstruction in relation to malunion of a distal femoral allograft.22 Eckhardt et all4 described 1 patient with lateral dislocation after resurfacing, successfully treated by medial imbrication, lateral release, and medial transfer of the patellar tendon. Other authors described patellofemoral pain treated conservatively or by revision. There is 1 report of patellofemoral impingement, although the details are not clear?,28*50 Authors' Preferred Approach. The authors do not resurface the patella routinely unless patellofemoral malalignment is present that might be improved by resurfacing, or the patella does not fit the prosthesis well. Even after an extra-articular resection, the authors try to avoid resurfacing because the bone often is thin, devascularized, and at risk of fracture. The authors have had 1 unusual complication in which a patellar button became loose and caused thrombosis of the popliteal artery (Fig. 12). TOTAL FEMORAL REPLACEMENT
Figure 11. This 37-year-oldman had resection of the proximal tibia for chondrosarcoma. A geometric excision was performed preserving the tibial tuberosity.
Occasionally, resection of the whole femur is required if malignancy extends far enough within it that a safe oncologic margin or stable reconstruction cannot be obtained. Alternatively, total femoral replacement may be indicated after revision of a partial replacement for local recurrence or loosening resulting in loss of bone stock. Some older prostheses did not have an articulating knee, but most contemporary implants do.43The risk of instability is increased because all of the soft tissues attached to the femur are released. In a series of 21 total femoral replacements reported by Ward et al,57there were 2 hip dislocations, including one that involved a 180" rotation of the implant around its long axis. The authors have not had significant problems with instability after total femoral replacement but are convinced that reattachment of the trochanter
INSTABILITY AFTER MAJOR TUMOR RESECTION
Figure 12. A 19-year-old man underwent extraarticular resection and patellar resurfacing for osteosarcoma of the distal femur. Nine years later, the patellar component displaced resulting in acute limb ischaemia.
is important for stability and abductor function (see Fig. 9).
References 1. Aboulafia AJ, Buch R, Mathews J, et al: Reconstruction using the saddle prosthesis following excision of primary and metastatic periacetabular tumors. Clin Orthop 314:203-213,1995 2. Abudu A, Grimer RJ, Cannon SR, et a1 Reconstruction of the hemipelvis after the excision of malignant tumours: Complications and functional outcome of prostheses. J Bone Joint Surg Br 79:773-779,1997 3. Aho AJ, Ekfors T, Dean PB, et a1 Incorporation and clinical results of large allografts of the extremities and pelvis. Clin Orthop 307:200-213,1994 4. Bell RS, Davis A, Allan DG, et a 1 Fresh osteochondral allografts for advanced giant cell tumors at the knee. J Arthroplasty 9:603409,1994 5. Bell RS, Davis AM, Wunder JS, et a1 Allograft reconstruction of the acetabulum after resection of stage-IIB sarcoma: Intermediate-term results. J Bone Joint Surg Am 79:1663-1674,1997 6. Brien EW, Terek RM, Healey JH, et a1 Allograft reconstruction after proximal tibia1 resection for bone tumors: An analysis of function and outcome comparing allograft and prosthetic reconstructions. Clin Orthop 303116-127,1994 7. Campanacci M, Capanna R Pelvic resections: The Rizzoli Institute experience. Orthop Clin North Am 22:65-86, 1991 8. Cannon SR Massive prostheses for malignant bone
709
tumours of the limbs. J Bone Joint Surg Br 79:497-506, 1997 9. Capanna R, Morris HG, Campanacci D, et al: Modular uncemented prosthetic reconstruction after resection of tumours of the distal femur. J Bone Joint Surg Br 76178-186,1994 10. Choong PF, Sim FH: Limb-sparing surgery for bone tumors: New developments. Semin Surg Oncol13:6469,1997 11. Choong PF, Sim FH, Pritchard DJ, et al: Megaprostheses after resection of distal femoral tumors: A rotating hinge design in 30 patients followed for 2-7 years. Acta Orthop Scand 67345351,1996 12. Clohisy DR, Mankin HJ: Osteoarticular allografts for reconstruction after resection of a musculoskeletal tumor in the proximal end of the tibia. J Bone Joint Surg Am 76:549-554,1994 13. de Meulemeester FR, Taminiau A H Saddle prosthesis after resection of a para-acetabular chondrosarcoma: A case report. Acta Orthop Scand 60363-364,1989 14. Eckardt JJ, Eilber FR, Rosen G, et al: Endoprosthetic replacement for stage IIB osteosarcoma. CGn Orthop 270202-213,1991 15. Gebhardt MC, Flugstad DI, Springfield DS, et a1 The use of bone allografts for limb salvage in high-grade extremity osteosarcoma. Clin Orthop 270:181-196,1991 16. Gradinger R, Rechl H, Hipp E: Pelvic osteosarcoma: Resection, reconstruction, local control, and survival statistics. Clin Orthop 270149-158,1991 17. Grimer RJ, Carter SR, Tillman RM, et a1 Endoprosthetic replacement of the proximal tibia [abstr]. J Bone Joint Surg Br 81:488-494,1999 18. Guest CB, Bell RS, Davis A, et a 1 Allograft-implant composite reconstruction following periacetabular sarcoma resection. J Arthroplasty 5(suppl):S25S34, 1990 19. Haentjens P, de Neve W, Casteleyn PP, et al: Massive resection and prosthetic replacement for the treatment of metastases of the trochanteric and subtrochanteric femoral region bipolar arthroplasty versus total hip arthroplasty. Acta Orthop Belg 59(suppl 1):367-371, 1993 20. Haentjens P, de Neve W, Opdecam P: [Prosthetic replacement for pathological fractures of the proximal end of the femur: Total prosthesis or bipolar arthroplasty?]. Rev Chir Orthop Reparatrice Appar Mot 80493-502,1994 21. Harrington KD, Johnston JO, Kaufer HN, et al: Limb salvage and prosthetic joint reconstruction for lowgrade and selected high-grade sarcomas of bone after wide resection and replacement by autoclaved [corrected] autogeneic grafts [published erratum appears in Clin Orthop 216:312, 1987. Clin Orthop 211:180-214,1986 22. Harris AI, Gitelis S, Sheinkop MB, et a1 Allograft prosthetic composite reconstruction for limb salvage and severe deficiency of bone at the knee or hip. Semin Arthroplasty 523594,1994 23. Hejna MJ, Gitelis S Allograft prosthetic composite replacement for bone tumors. Semin Surg Oncol 13:1824,1997 24. Hornicek FJ, Gebhardt MC, Sorger JI, et a1 Tumor reconstruction. Orthop Clin North Am 30:673-684,1999 25. Hornicek FJ Jr, Mnaymneh W, Lackman RD, et a1 Limb salvage with osteoarticular allografts after resection of proximal tibia bone tumors. Clin Orthop 352179-186, 1998 26. Horowitz SM, Glasser DB, Lane JM, et al: Prosthetic and extremity survivorship after limb salvage for
710
GERRAND et a1
sarcoma: How long do the reconstructions last? Clin Orthop 293:280-286,1993 27. Horowitz SM, Lane JM, Otis JC, et a1 Prosthetic arthropla’sty of the knee after resection of a sarcoma in the proximal end of the tibia: A report of sixteen cases. J Bone Joint Surg Am 73:28&293,1991 28. Hsu RW, Sim Fw,Chao EY Reoperation results after segmental prosthetic replacement of bone and joint for limb salvage. J Arthroplasty 14519-526,1999 29. Jofe MH, Gebhardt MC, Tomford WW, et a1 Reconstruction for defects of the proximal part of the femur using allograft arthroplasty. J Bone Joint Surg Am 70507-516,1988 30. Kabukcuoglu Y, Grimer RJ, Tillman RM, et a1 Endoprosthetic replacement for primary malignant tumors of the proximal femur. Clin Orthop 358:s-14,1999 31. Karaharju EO, Korkala OL Resection of large tumors of the anterior pelvic ring while preserving functional stability of the hip. Clin Orthop 195:270-274,1985 32. Kawai A, Muschler GF, Lane JM, et a1 Prosthetic knee replacementafter resection of a malignant tumor of the distal part of the femur: Medium to long-term results. J Bone Joint Surg Am 80:636447,1998 33. Kusuzaki K, Shinjo H, Kim W, et al: Resection hip arthroplasty for malignant pelvic tumor: Outcome in 5 patients followed more than 2 years. Acta Orthop Scand 69:617-621,1998 34. Lan F, Wunder JS, Griffin AM, et a1 Measurement of periprosthetic bone remodelling around distal femur tumor prostheses with dual energy x-ray absorptiometry (DEXA) scans. J Bone Joint Surg Br 82:120-125, 2000 35. Langlais F, Vielpeau C: Allografts of the hemipelvis after tumour resection: Technical aspects of four cases. J Bone Joint Surg Br 71:5&62,1989 36. Leung PC: Reconstruction of the pelvic ring after tumour resection. Int Orthop 16:16%171,1992 37. Malawer MM, Chou LB Prosthetic survival and clinical results with use of large-segment replacements in the treatment of high-grade bone sarcomas.J Bone Joint Surg Am 7711541165,1995 38. Malkani AL, Settecerri JJ, Sim FH, et al: Long-term results of proximal femoral replacement for nonneoplastic disorders. J Bone Joint Surg Br 77:351-356, 1995 39. Masterson EL, Ferracini R, Griffin AM, et al: Capsular replacement with synthetic mesh: Effectiveness in preventing postoperative dislocation after wide resection of proximal femoral tumors and prosthetic reconstruction. J Arthroplasty 132360-866,1998 40. McGoveran BM, Davis AM, Gross AE, et a 1 Evaluation of the allograft-prosthesis composite technique for proximal femoral reconstruction after resection of a primary bone tumour. Can.J Surg 42:3745, 1999 41. Mnaymneh W, Malinin TI, Lackman RD, et al: Massive distal femoral osteoarticular allografts after resection of bone tumors. Clin Orthop 303:103-115,1994 42. Morris HG, Capanna R, Del Ben M, et al: Prosthetic
reconstruction of the proximal femur after resection for bone tumors. J Arthroplasty 10:293-299,1995 43. Nerubay J, Katznelson A, Tichler T, et a1 Total femoral replacement. Clin Orthop 229:14>148,1988 44.Nielsen HK, Veth RP, Oldhoff J, et a1 Resection of a periacetabular chondrosarcoma and reconstruction of the pelvis: A case report. J Bone Joint Surg Br 67413-415, 1985 45. 0Connor M I Malignant pelvic tumors: Limb-sparing resection and reconstruction. Semin Surg Oncol13:4954,1997 46. 0 Connor MI, Sim FH: Salvage of the limb in the treatment of malignant pelvic tumors. J Bone Joint Surg Am 71:481494,1989 47. Ozaki T, Hillmann A, Bettin D, et a1 High complication rates with pelvic allografts: Experience of 22 sarcoma resections. Acta Orthop Scand 67333-338,1996 48. Porsch M, Kornhuber B, Hovy L: Functional results after partial pelvic resection in Ewing’s sarcoma of the ilium. Arch Orthop Trauma Surg 119:199-204,1999 49. Renard AJ, Veth RP, Schreuder HW,et a1 Revisions of endoprosthetic reconstructions after limb salvage in musculoskeletal oncology. Arch Orthop Trauma Surg 117125131,1998 50. Shin DS, Weber KL, Chao EY, et a 1 Reoperation for failed prosthetic replacement used for limb salvage. Clin Orthop 358:53-63,1999 51. Sim FH, Bowman WE Jr, Wilkins RM, et al: Limb salvage in primary malignant bone tumors. Orthopedics 83574-581,1985 52. Simon MA: Limb salvage for osteosarcoma. J Bone Joint Surg Am 70:307-310,1988 53. Springfield DS: Allograft reconstructions. Semin Surg Oncol13:11-17,1997 54. Thomas IH, Cole WG, Waters KD, et a1 Function after partial pelvic resection for Ewing’s sarcoma. J Bone Joint Surg Br 69:271-275,1987 55. Uchida A, Myoui A, Araki N, et a 1 Prosthetic reconstruction for periacetabular malignant tumors. Clin Orthop 326:23&245,1996 56. Unwin PS, Cannon SR, Grimer RJ, et a1 Aseptic loosening in cemented custom-made prosthetic replacements for bone tumours of the lower limb. J Bone Joint Surg Br 78513,1996 57. Ward WG, Dorey F, Eckardt JJ: Total femoral endoprosthetic reconstruction. Clin Orthop 316:195-206,1995 58. Windhager R, Karner J, Kutschera HP, et a 1 Limb salvage in periacetabular sarcomas: Review of 21 consecutive cases. Clin Orthop 331:265-276,1996 59. Wirganowicz PZ, Eckardt JJ, Dorey FJ, et al: Etiology and results of tumor endoprosthesis revision surgery in 64 patients. Clin Orthop 358:64-74,1999 60. Zatsepin ST, Burdygin V N Replacement of the distal femur and proximal tibia with frozen allografts. Clin Orthop 303:95-102,1994 61. Zehr RJ, Enneking WF, Scarborough MT: Allograftprosthesis composite versus megaprosthesis in proximal femoral reconstruction. Clin Orthop 322:207-223, 1996
Address reprint requests to Robert S. Bell, MD, MSc, FRCSC The University Musculoskeletal Oncology Unit Mount Sinai Hospital, Suite 476 Toronto, Ontario, M5G 1x5 Canada
0030-5898/01 $15.00
+
.OO
INSTABILITY AFTER MAJOR TUMOR RESECTION Prevention and Treatment Craig H. Gerrand, MB, ChB, Robert S. Bell, MD, MSc, FRCSC, Anthony M. Griffin, BSc, and Jay S. Wunder, MD, MSc, FRCSC
Limb-sparing surgery has become accepted as standard surgical treatment for primary bone sarcoma.s,10,24,46, 51, 52 Most bone resections involve joints, and the resection of periarticular muscle, ligament, and tendon to achieve a negative margin is not conducive to a stable reconstruction. Instability adds morbidity to a procedure, reduces functional outcome, and may lead ultimately to failure of the reconstru~tion.~~ This article discusses reconstructive techniques in the pelvis and lower limb with particular emphasis on the problem of instability, including instability of the pelvis. Stability is defined as the ability of the reconstruction to withstand physiologic loading, rather than simply avoiding dislocation. This definition is particularly significant when discussing stability in the pelvis. PELVIC RESECTION Improved imaging techniques and neoadjuvant therapies have increased the number of limb-sparing procedures performed for malignant pelvic tumors. Local and systemic relapse rates remain high, however.2,5, la,45, 46, 55, 58 Limb Supported by The Wishbone Trust, Ethicon, Depuy UK, and Stryker Howmedica (CHG).
salvage is appropriate when a satisfactory surgical margin can be obtained or when an amputation cannot provide a better surgical margin. For the purposes of this discussion, instability of the pelvis is defined as loss of osseous continuity between the femur and the ipsilatera1sacrum. Pelvic stability may be maintained after resection of the anterior pelvis or incomplete resection of the ilium, which maintains the arch of the sciatic notch. Complete resection of the ilium may require reconstruction, however, and periacetabular resections are particularly challenging.2,5, la,45,55, 58 After pelvic resection, the decision to reconstruct and the mode of reconstruction are influencedby many factors, including the condition of the patient at surgery, the prognosis, the functional demands of the patient, the extent of the resection, and the availability of implants and allografts. Proponents of anatomic reconstruction believe that it is important to restore the bony anatomy and mechanical stability of the pelvis. Given the significant complication rates associated with pelvic reconstruction, however, resection without reconstruction may be reasonable in certain circumstance^.^^ OConnor and Sim4'jfound that the pelvis became unstable after 37 of 60 resections (62%). When the pelvis remained stable, the average
From the University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto, Ontario, Canada (CHG, RSB, AMG, JSW); and the Department of Orthopaedics, University of Glasgow, Glasgow, United Kingdom (CHG)
ORTHOPEDIC CLINICS OF NORTH AMERICA VOLUME 32 * NUMBER 4 * OCTOBER 2001
697
698
G E R U N D et a1
functional score using the modified Musculoskeletal Tumour Society (MSTS) system (1987) was 33 out of a total 35 points. When the resection resulted in instability but stability was restored by reconstruction,the average MSTS score was 28 points. When stability was not restored, the average MSTS score was only 15 points.
Iliac Resection After resection of the ilium, reconstruction may be anatomic (the hip joint is restored to its normal level, and the pelvic ring is reconstituted) or nonanatomic (the iliac stump is approximated to the sacrum). Many reconstructive techniques have been described, including primary arthrodesis with wires and bone grafting with vascularized or nonvascularized autografts, allografts, or custom implants, but all of these techniques have a significant complication rate.2,s, 34, 36, 46, ss, 58 Nonanatomic reconstructionmay lead to limblength inequality, sciatic or obturator nerve entrapment, and ultimately scoliosis and back pain. If no reconstruction is performed, a large abdominal hernia and painful pseudarthrosis may r e ~ u l t . ~ Campanacci and Capanna7 reported the results of 32 sacroiliac resections. In 15 cases, the iliac resection was subtotal, and pelvic stability was maintained. Functional results were excellent in 10 cases, good in 4, and fair in 1. Three of 6 patients who had complete iliac resection without reconstructionhad satisfactory outcomes compared with 3 of 4 patients who had reconstruction using intercalary allografts. Campanacci and Capanna7 recommended reconstruction of the pelvic ring. OConnor and Sim46reported 17 sacroiliac resections. In 7 cases, resection was above the level of the sciatic notch, the pelvis remained stable, and functional results were excellent in 6 and good in 1. In 5 cases with a successful iliosacral arthrodesis, results were excellent in 3 and good in 2. Of 2 cases with a pseudarthrosis, results were fair in 1 case and poor in the other. No attempt at reconstruction was made in 3 cases, and the results were good in 1, fair in 1, and poor in 1. OConnor and Sim46 implied that reconstruction should be done if possible. Ozaki et a147described 12 patients who had iliac resection and iliosacral arthrodesis using allograft. The grafts were fixed with large cancellous screws, which loosened in 3 patients. There were 2 deep infections, 1 fracture, and
1 nonunion. Functional scores for 10 patients with grafts in situ were excellent in 3, good in 6, and fair in 1. There was no comparison in this series with other methods of treatment. Porsch et a148described 6 patients who had iliac resection for Ewing’s sarcoma and reconstruction with autograft. One patient did not undergo reconstruction and developed pelvic instability and pain, which were alleviated by late reconstruction with a vascularized fibular graft. Porsch et a148believed that outcome was related to pelvic stability and that reconstruction of the defect would improve functional results. Thomas et a154reported on 3 complete iliac resections for Ewing’s sarcoma. Two were reconstructed with Steinmann pins and autogenous bone graft. Reconstruction reduced but did not prevent limb shortening, and all patients had some degree of pelvic instability. The patient who did not undergo reconstruction had a poor functional result. Thomas et a154favored reconstruction. Authors’ Preferred Approach. If iliac resection is subtotal and the sacroiliac joint is not involved, there is no requirement for reconstruction. The authors do not attempt to fill, the defect. If the resection involves the sacroiliac joint, there is the potential for instability. The authors recommend fusion with interfragmentary cancellous screws if the residual ilium and sacrum can be approximated adequately (Fig. 1). The authors do not reconstruct the pelvis routinely after complete iliosacral resection. The authors reviewed 13 patients who underwent iliosacral resection. Four patients underwent reconstruction, and 9 did not. The groups had similar functional outcomes and general health status measures, but the reconstructed group had a significantly higher complication rate, increased blood loss at surgery,and longer hospitalization. None of the patients without reconstruction have had sciatic nerve symptoms (Fig. 2).
Periacetabular Resections Reconstruction of the hip after resection of the acetabulum is challenging. Among the techniques described are endoprosthetic replacement, saddle prosthesis, allograftprosthesis composites, arthrodesis and surgical pseudarthrosis.’,13, 34, 35, 47, 58 The complication rates of all techniques are significant. Instability of the hip joint as well as the pelvis may be a problem.
INSTABILITY AFTER MAJOR TUMOR RESECTION
699
Uchida et a155described a constrained implant, with a cup fixed into the remaining ilium or sacrum with cement and screws and a long cemented femoral stem. In a series of 18 patients with primary and metastatic tumors in the acetabular region, 2 had dislocations after a fall requiring revision of the implant. Saddle Prosthesis
Figure 1. This 34-year-old woman underwent iliosacral resection for chondrosarcoma. The residual sacroiliac joint was fused with cancellous screws and has united.
Endoprostheses Endoprosthetic reconstruction of the pelvis is associated with significant rates of infection and dislocation. Matching the implant to the recipient is difficult, and most implants are custom-made.2,16,44,55, 58 Abudu et a12 described the use of a custom-made titanium implant with a polyethylene cup, articulating with a conventional Stanmore femoral prosthesis with a 32-mm head. The implants were fixed with pins and cement into the residual ilium. In a series of 35 patients, 9 (26%) developed a deep infection. Six patients (17%) developed recurrent dislocation treated by closed reduction and physiotherapy and, in 1 case, by revision of the cup. Two implants loosened but subsided into a stable position. Windhager et a158 described a customized implant manufactured from a three-dimensional model of the pelvis on which the extent of the tumor and the planned resection margins were marked. Postoperatively the patients were placed in a plaster cast for 6 weeks and a hip brace for 4 to 6 months. Functional results of 5 patients with more than 12 months’ follow-up revealed that all had a positive Trendelenburg sign. There was 1 hip dislocation and 1 deep infection.
Although the saddle prosthesis was designed for hip reconstruction after failed arthroplasty and acetabular bone loss, it may be used after periacetabular resection for tumor, despite the potential problems of a large residual dead space and a nonanatomic hip center.’,’3,58 The saddle articulates with a notch cut in the remaining ilium. If the ilium has been resected completely, it may be possible to construct an articulation using allograft or cement fixed to the sacrum.’ Stability of the reconstruction depends heavily on soft tissue tension, and reconstruction may be contraindicated in cases in which the abductor or iliopsoas muscles have been resected. Aboulafia et al’ described their experience of the saddle prosthesis in 17 patients, 8 with primary malignancies and 9 with metastatic disease involving the pelvis. Patients received 2 to 4 weeks of traction postoperatively and 6 to 12 weeks of bracing. There were 2 prosthetic dissociations and 2 dislocations.’ Windhager
Figure 2. This 32-year-old woman had a sacroiliac resection for Ewing’s sarcoma. The defect was not reconstructed and a stable pseudarthrosis developed. She walks well with a cane and a shoe lift.
700
G E R U N D et a1
et a15' reported functional results in 4 patients after periacetabular resection. Function was good in 1 case, fair in 2, and poor in 1. Of 5 patients who had endoprosthetic reconstruction, function was good in 3, fair in 1, and poor in 1. Windhager et a158concluded that functional outcome was better after reconstruction with a custom implant.
Allograft-Implant Composite The advantages of using an allograft for reconstruction of the pelvis include healing to and partial replacement by host bone and the ability to shape the allograft to fit the defect at the time of surgery and soft tissue attachments. Disadvantages include a high infection rate, the risk of viral transmission, and allograft fracture, which may lead to pelvic i n ~ t a b i l i t y . Ozaki ~ ~ , ~ ~et a147 described 9 patients who underwent reconstruction with an allograft, a cemented acetabular cup, and a cementless femoral component. There were 5 infections and 1 allograft fracture. Ozaki et a147concluded that the complicationrate was unacceptable. 4 cases usLanglais and V i e l p e a ~described ~~ ing allografts and a standard cemented total hip prosthesis. Three braided polypropylene ligaments were used to stabilize the hip. One was placed transversely across the neck of the femoral implant to prevent upward subluxation, one was placed anteriorly to limit external rotation, and one was placed posteriorly to limit internal rotation. The rim of the iliac crest with its soft tissue attachments was preserved and attached to the graft. There were no dislocations and no infections.
thesis resulting in painless pseudarthrosis. Capanna et a19preferred ischiofemoral arthrodesis when the inferior and medial acetabulum had been retained, but noted that the pelvis may tilt, hinging on the pubic symphysis and causing scoliosis, unless the pelvic ring was reconstituted. Of 14 attempted iliofemoral arthrodeses, OConnor and Sim46reported 6 successful fusions, 4 stable pseudarthroses, and 4 failures. In 2 cases, an intercalary allograft was used to restore length to the leg or to allow fusion to the sacrum. Both allografts became infected, and a flail limb was the end result. Ischiofemoral arthrodesis was attempted in 3 cases; the arthrodesis was successful in 1case, resulted in a stable pseudarthrosis in 1case, and was followed by amputation for recurrence in 1 case. One attempt at ischiofemoralpseudarthrosis resulted in a stable femorosacral pseudarthrosis. Functional outcome was better when a stable arthrodesis had been achieved.46 Authors' Preferred Approach. If the femoral head can be preserved despite acetabular resection and it is possible to avoid shortening the limb by more than 5 or 6 cm, iliofemoral arthrodesis is performed. Despite the loss of leg length, the durability of this physiologic reconstruction is appealing when union has been achieved (Fig. 3).
Arthrodesis If there is sufficientbone stock, continuity between the pelvis and femur may be restored by iliofemoral or ischiofemoral arthrodesis. The major advantage of this approach is that it provides a stable and durable reconstruction. Disadvantages include leg shortening, lack of hip mobility, and long consolidation times. Arthrodesis may be difficult to achievebecause of the small contact area, the long lever of the lower limb acting through the arthrodesis site, and the fact that the local blood supply may be compromised by surgery and radiotherapy. Capanna et a19 could achieve iliofemoral arthrodesis in only 50% of cases and suggested that the goal of treatment should be iliofemoral coaptation with minimal osteosyn-
Figure 3.This 17-year-old patient presented with Ewing's tumour of the left hemipelvis. His original arthrodesis was revised twice before solid fusion was achieved.
INSTABILITY AFTER MAJOR TUMOR RESECTION
After more extensive periacetabular resection (especially if the femoral head cannot be salvaged), the authors' preference for reconstruction depends on the extent of remaining ilium. Previously the authors performed reconstruction in almost all patients with an allograft-implant composite, but if there is sufficient bone stock, presently the authors prefer to use a saddle prosthesis. The saddle prosthesis enhances the stability of the construct with a Dacron aortic vascular graft passed over the iliac crest or through a small window in the upper ilium and sutured under tension to the implant. The authors had 1 case in which, despite the graft, the saddle dislocated when the patient fell heavily during a period of postoperative confusion (Fig. 4). If it is necessary to resect the acetabulum and the ilium as far posteriorly as the sacroiliac joint (or through the sacral ala), an allograft is used, always in conjunction with a total hip arthroplasty. The allograft is shaped to fit the defect and held to host bone with long cancellous screws with or without additional neutralization plates. Before implantation, the allograft is prepared to accept a cemented cup, and care is taken to place it in a horizontal position (Figs. 5 and 6 ) . If the hip is grossly unstable and the capsule cannot be reconstituted using host and allograft soft tissues, it can be augmented with hhrlex or Dacron (Fig. 7). In a series of 10 patients reconstructed with an allograft-implant composite, there were 4 dislocations. Three dislocations stabilized
Figure4. This 61-year-old man had a periacetabular resection for chondrosarcoma. A saddle prosthesis was used for the reconstruction but dislocated after a fall.
701
Figure5. This 56-year-old man underwent pelvic resection for high grade leiomyosarcoma and reconstruction with a hemipelvic allograft and cemented total hip arthroplasty. At 4-year follow-up, the graft has united to the sacrum. The patient used two canes for walking.
Figure 6. This 32-year-old woman had a pelvic chondrosarcoma treated by resection and reconstruction with a hemipelvic allograft secured with neutralization plates. At 10-year follow-up, the allograft has united and the patient has excellent function.
702
GERRAND et a1
Figure 7. A, After resection of the femur, a sheet of Marlex mesh is sutured to the capsular remnant using a nonabsorbablesuture. 6,The mesh is tightly wrapped around the neck of the prosthesis and sutured to itself to create a new hip capsule. C, The prosthesis within the tube of mesh has been sutured into position. (From Masterson EL, Ferracini R, Griffin AM, et al: Capsular replacement with synthetic mesh. J. Arthroplasty 13:860-866, 1998; with permission).
spontaneously after closed reduction. One required trochanteric advancement to achieve stability. In 2 cases, the limb deliberately was lengthened 3 cm to increase the soft tissue tension. Both cases had partial sciaticnerve palsies that recovered slowly.1s In a series of 17 patients managed with a pelvic allograft with a minimum 4-year followup, 3 patients died of metastatic disease, 3 had local recurrence, and 2 had deep infection of the allograft. Two patients were managed as an osteoarticular reconstruction but had unsatisfactory outcomes; 1 patient had local recurrence, and the other was revised to an allograft-implant composite. Allograftimplant reconstruction rather than osteoarticular allograft reconstruction is appropriate in this situation. Eight patients were alive with their original allograft in situ; 7 had MSTS (1993) functional scores averaging 72%; the other patient had chronic subluxation of the hip and a poor r e ~ u l t . ~
lschiopubic Resection Because it does not involve interruption of continuity between the femur and the sacrum, resection of the anterior pelvis alone is not associated with instability, reconstruction usually is not required, and functional results are good. Campanacci and Capanna7reported 11 excellent, 2 good, and 3 fair results in 16 ischiopubic resections. OConnor and Sim46reported 10 excellent and 1good functional result in 11 cases. Occasionally, resection of the anterior pelvis may involve the acetabulum. If the superior portion of thh acetabulum can be maintained, careful capsular repair and postoperative bracing may result in a stable hip.31Some workers suggest the use of Steinmann pins to maintain reduction during soft tissue healing7 Authors’ Preferred Approach. It is not the authors’ practice to reconstruct the bone defect after anterior pelvic resection. The authors use
INSTABILITY AFTER MAJOR TUMOR RESECTION
a pedicled fascia lata rotation flap to close the soft tissues at the front of the pelvis. If the resection involves the inferior part of the hip joint, care is taken to repair the capsule at the end of the procedure, and postoperatively a brace is used. If the hip remains unstable, the authors’ preferred reconstruction is arthrodesis. PROXIMAL FEMUR
The proximal femur is a common site for primary bone sarcoma, especially chondrosarcoma. Local anatomy allows most tumors to be managed with limb-sparing surgery because important neurovascular structures usually are not involved. If the hip joint is spared, an intraarticular resection is adequate. If there is suspicion that the hip is involved, a more radical resection may be required involving the periarticular soft tissues, which makes stable reconstruction more difficult. If there is gross contamination of the hip joint, it may be necessary to perform a true extra-articular resection, including acetabulum. The 2 factors crucial to determining stability after reconstruction of a proximal femoral tumor are (1) whether it is necessary to resect capsule and the proximal muscles that attach the femur to the pelvis (external rotators, iliopsoas, proximal adductors) and (2) whether it is possible to reconstruct the trochanter and abductor attachment. Options for reconstruction include endoprosthetic replacement, allograft-prosthesis composites, osteoarticular allografts, and arthrodesis. Each presents particular issues related to stability. Endoprostheses
The major advantage of endoprosthetic reconstruction is that it allows immediate or early joint motion and weight bearing. This advantage may be particularly important when adjuvant chemotherapy is planned or if life expectancy is limited. In the largest reported series, the probability of surviving aseptic loosening of a cemented proximal femoral prosthesis was 94% at 10 years.56Joint instability is a major concern, with dislocation rates of 3% to 36% r e p ~ r t e d . ” , Malkani ~ ~ , ~ ~ et aP8 reported dislocation in 11 of 50 patients who underwent proximal femoral replacement for nonneoplastic disorders and found a relationship with multiple previous procedures and abductor insufficiency. Dislocation rates are thought to be lower when a bipolar head is
703
used and when the abductors are reconstructed adequately8,20,59 Most authors emphasize the importance of careful capsular repair. Kabukcuoglu et aBO reported the results of 54 proximal femoral replacements using custom-made femoral implants with a 29-mm or 32-mm head and a cemented polyethylene cup. The mean follow-up time was 9 years. There were 6 dislocations. Four of these stabilized after closed reduction and rehabilitation, and 2 were revised. Morris et a142reported 31 proximal femoral replacements using the Kotz (Howmedica Modular Resection System, Howmedica, Rutherford, NJ) modular replacement system. In 29 cases, a bipolar head was used. There was 1dislocation of a bipolar prosthesis and 1 deep infection. Haentjens et all9 reviewed 28 patients with metastatic disease. If the acetabulum was involved, a total hip arthroplasty was performed. If the acetabulum was spared, a bipolar head was used. There were 4 dislocations in 11 patients in the total hip arthroplasty group and none in the bipolar group. Allograft-Implant Composites
Allograft-implant composites offer biologic reconstruction that restores bone stock and allows load sharing with the prosthesis. Enhanced soft tissue reconstruction may improve implant stability.61Disadvantages include fracture, infection, nonunion, graft resorption, and risk of viral disease transmission. Jofe et alZ9reported medium-term results in 13 patients. Jofe et alZ9emphasized the need for careful soft tissue repair of the capsule and abductors. There were no dislocations, 2 allograft fractures, and 1 infection. Nine Austin Moore hemiarthroplasties, 3 of which subsequently were revised for pain; 2 bipolar prostheses; and 2 total hip arthroplasties were used. Jofe et alZ9believed that these results were better than those obtained by osteoarticular allograft. Harris et alZ2 reported the results of 11 patients who had allograft-prosthesis composite reconstruction of the proximal femur after resection for tumor. There were 5 nonunions but no dislocations. Zehr et a16’ compared the outcomes and complication rates of allograft-prosthesiscomposites and endoprostheses in the reconstruction of the proximal femur. There was at least 1 episode of instability in 5 of 18 endoprosthetic reconstructions but none of 18 composite reconstructions. Four of the unstable
704
GERRAND et a1
reconstructions had a total hip arthroplasty rather than a bipolar hemiarthroplasty. Osteoarticular Allografts
Several authors reported the use of osteoarticular allografts to replace the proximal femur. Matching the sizes of the graft and host acetabulum preoperatively is difficult, and the surgeon may need to proceed to an allograftprosthesis composite if the fit is unsatisfactory. The allograft requires a long rehabilitation period with protected weight bearing. In the longer term, there are reports of joint colla se and cartilage fragmentati~n.~~ Jofe et a1 reported 15 cases in which the proximal femur was replaced by an osteoarticular allograft. There were 4 infections, 3 fractures, 2 nonunions, and 1unstable hip.29 Authors’ Preferred Approach. In general, the authors prefer the use of a modular femoral endoprosthesiswith a bipolar head, although this does not guarantee against dislocation (Fig. 8). If the articular cartilage of the acetabulum is in poor condition, acetabular resection has been performed, or the patient’s acetabulum is too small for the smallest available implant, a cemented polyethylene cup is used. The greater trochanter is osteotomized and reattached to the implant if possible. Reattaching the trochanter to a bone ingrowth surface results in improved abductor function (Fig. 9). If the greater trochanter cannot be preserved, the abductor tendon is attached to
P
Figure 8. This 24-year-old woman had resection of the proximal femur for Ewing’s sarcoma. Her acetabulum was too small for the smallest available bipolar implant and therefore a cemented cup was used. Despite capsular reconstruction she went on to experience recurrent dislocation.
Figure 9. This 18-year-old woman had total femoral resection for osteosarcoma. The greater trochanter is firmly reattached to the bone ingrowth surface on the implant. The patient had grade 4 abductor power.
the implant or the surrounding soft tissues. The hip joint capsule usually is resected with the proximal femur, although the labrum is maintained. Stability of the reconstruction is assessed on the operating table, after optimizing implant alignment and limb length. If the hip remains unstable despite these measures, the capsule can be reinforced with synthetic mesh attached to the labrum or with bone sutures to the acetabulum (see Fig. 7). The authors reviewed their experience of capsular replacement in 13cases after proximal femoral reconstruction. None of 4 patients who had a bipolar articulation and capsular replacement experienced dislocation compared with 4 of 9 who had a total hip arthroplasty. All patients in this series had extremely unstable implants after resection of
INSTABILITY AFTER MAJOR TUMOR RESECTION
all muscles surrounding the hip and the hip capsule.39 In the authors' experience of allograftimplant composites, the functional results were disappointing. Although the abductor tendon could be attached to the allograft soft tissues, this did not translate into better abductor function. When the host greater trochanter was attached with wires onto allograft, however, abductor function was improved.40The authors reserve the use of an allograft-prosthesis composite for cases in which the greater trochanter can be preserved, and the level of the osteotomy is such that it can be bridged by a long-stemmed hip prosthesis. DISTAL FEMUR The distal femur is the most common site for primary bone tumors. An osteoarticular allograft may be considered in cases in which resection is intra-articular and the opposite joint surface and joint motors can be preserved. This approach may be particularly useful in a growing child. Reconstructive options after extra-articular resection include endoprostheses, osteochondral allografts, and allograft-prosthesis composite^.'^ In considering stability of a reconstructive procedure for the distal femur, it is necessary to assess translational and angular stability of the femorotibial joint as well as the congruity of the patellofemoral articulation. Endoprostheses
After resection of the distal femur, an endoprosthesishas the advantage of restoring stability immediately. Most implants have a degree of constraint in their design that imparts stability without depending on soft tissue stabilizers, many of which may have been excised. Most implants incorporate a degree of hyperextension, which allows a patient with a weak extensor mechanism to lock the knee in full extension and enhances the stance phase of gait.32Implant failure rates are increased in the presence 32, 56 of extensive bone and soft tissue re~ection.~, Although a direct comparison between studies is difficult, more constrained implants may be associated with early failure. Unwin et a156reported results of 493 distal femoral replacements with a custom implant based on a fully constrained knee. The probability of surviving aseptic loosening was
705
reported as 67% at 10 years. In a series of 40 patients, Kawai et aP2 reported survival of a semiconstrained knee as 85%,67%,and 48% at 3, 5, and 10 years. Capanna et a19 reported results of the uncemented Kotz modular tumor reconstruction system in 95 patients. This system has a simple hinge articulation based on a metal axle within a polyethylene bushing. The bushing failed in 42% of cases at a mean of 64 months postoperatively and was the most common reason for revision. Bushing failure produces mild coronal instability, although this is p a i n l e ~ s .Bushings ~,~~ for this prosthesis have been redesigned and markedly improved. Horowitz et alZ6reported 59%5-year event-free prosthetic survival for a constrained design. Rotating hinge designs have the theoretic advantage of providing stability and reducing stress transfer across the knee by permitting flexion and extension, rotation, and axial translation. Malawer and ch01.1~~ reported revisions of 3 of 31 distal femoral replacements at a mean of 3.5 years. Of these, 27 were rotating hinge designs. Choong et al" reported results in 30 patients treated with an implant based on a kinematic rotating hinge. There were 2 failures in 32 implants at 5 years. Eckhardt et all4 reported results of 52 distal femoral replacements with a rotating hinge knee. Four were revised for mechanical complications at a median of 44 months. Few authors commented on patellar instability or anterior knee pain after prosthetic reconstruction of the distal femur. Most tumor prostheses have deep, constrained patellar grooves, which likely compensate for the extensive soft tissue resections necessary for tumor resection. Osteochondral Allograft
Immediate stability of a reconstruction using an osteochondral allograft depends on sound soft tissue repair, the correct size of allograft, and graft fixation. Primary repair or reconstruction of the cruciate ligaments and patellar tendon are i m p ~ r t a n t . ' ~ Late , ~ ~instability follows failure of the soft tissue reconstruction or allograft collapse and may lead to subluxation I2f4l and degenerative arthriti~.~, Mnaymneh et al4I reviewed 96 patients who had reconstruction of the distal femur with an osteochondral allograft. Six (7%)patients had knee joint instability caused by ligamentous laxity and used a brace or crutches. Mnaymneh et a141 suggested this was secondary to
706
GERRAND et a1
inadequate soft tissue repair or anatomicincongruity and emphasized the need for anterior ceciate reconstruction, using semitendinosus or Achilles tendon allograft. Three of the 6 patients had associated complications of fracture, arthritis, and non~nion.~' In a series of 11 patients reported by Gebhardt et al,15 only 1 had an unstable joint. Aho et aP reported results of 11 patients with a mixture of benign and malignant conditions. Functional results were good or excellent in 7, fair in 1, and a failure in 3. Zatsepin and Burdygin60 reported longterm results in 88 patients. The allograft was fixed to the host with a step osteotomy. Of 76 patients for whom results were known, 37 walked without aids, 22 used a cane, and 17 had fractures requiring a crutch or conversion to an endoprosthesis. Zatsepin and BurdygidO noted a progressive reduction in knee movement with time and ultimately deformity and arthritic change. Treatment of instability around the knee usually involves custom bracing or total joint arthroplasty. The osteochondral allograft has the advantage that if revision to an arthroplasty is required and the allograft has healed, bone stock is r e s t ~ r e d . ~ , ' ~ , ' ~
a variable period. The authors routinely assess coronal instability at review appointments and exchange bushings when necessary. This problem has been resolved since the bushing design was revised substantially. The authors prospectively compared functional outcomes and health status data after 31 Kotz fixed-hinge, uncemented, distal femoral replacements with 25 cemented rotatinghinge tumor replacement prostheses (Howmedica Modular Resection System).At a mean follow-up of almost 3 years, functional scores were significantly better in the rotating-hinge group The authors continue to use the fixed hinge with an enhanced bearing, however, to avoid the use of cement in these young patients. Fresh osteochondral allografts have the theoretic advantage of providing an articular surface with viable chondrocytes. A major disadvantage is the time it takes to find a suitable donor, making this technique unsuitable for most malignant lesions. The authors studied fresh osteochondral allograft reconstruction at the knee in the reconstruction of advanced giTen ant cell tumors in 16 patients (Fig. reconstructions were of the distal femur, and 6 were of the proximal tibia. Two grafts were revised for unstable fractures of the distal
Allograft-Implant Composites
There are few reported results of reconstruction using allograft-implant composites in the literature. Harris et alZ reviewed 9 reconstructions using a kinematic rotating hinge or a total condylar revision prosthesis. Complications included 1 patellar subluxation, but there were no dislocations. Hejna and GitelisZ3suggested that the constraint of the implant used should reflect the degree of soft tissue resection.If a significant amount of quadriceps muscle has been resected, a constrained device, such as a fixed hinge or rotating hinge, is required. In cases with minimal resection, a less constrained device, such as a constrained condylar knee, may be more suitable. Authors' Preferred Approach. After resection of the distal femur, the authors prefer endoprosthetic replacement with a cementless stem and use the Kotz modular system. The authors do not insert locking screws routinely to reduce stress shielding and have not found primary stability of the implant to be compromised'33The most significant problem the authors have experienced is failure of the fixed-hinge bushing mechanism after
Figure 10. This patient had a giant cell tumour of the distal femur treated by surgical resection and reconstruction with a fresh osteochondral allograft that has united to host bone.
INSTABILITY AITER MAJOR TUMOR RESECTION
femur. One was converted to a total knee arthroplasty with maintenance of the allograft after a femoral condyle fracture, and there was 1deep infection. Coronal instability was found in all but 1 of 13 patients at long-term review. This patient had an excellent functional result. All of the patients with fair and poor results had significant joint instability often requiring the use of a brace. The authors no longer use osteoarticular allografts for reconstruction of tumors at the knee.
707
58% at 10 years and that the risk was increased with the amount of tibia resected. Horowitz et a127described 16 patients, all of whom had an extra-articular resection of the knee, followed for 2 to 10 years. All the implants were a constrained ball-and-socket design. The patella was screwed to the endoprosthesis to restore extensor function. There were 2 infections, and 3 components became loose in the first 33 months. Allograft-Implant Composites
PROXIMAL TIBIA
Reconstruction of the proximal tibia presents a particular challenge because of the need to reattach the patellar tendon, obtain adequate soft tissue cover, and preserve the neurovascular structures, which are extremely close to bone in this area. Available surgical options include arthrodesis by one of several methods, rotationplasty, and amputation. Salvage of the knee joint is a major advantage in functional terms, but resection of soft tissues around the knee leaves the potential for instability.
The use of an allograft-implant composite facilitates reconstruction of the patellar tendon. The bulk of the allograft makes it essential, however, to provide cover with a gastrocnemius flap. A long-stemmed implant may bridge the junction between allograft and host. Alternatively a short-stemmed implant can be used if the allograft is plated to the host. The choice of implant is determined by the amount of soft tissue resection and the constraint required.23 Osteochondral Allograft
Endoprostheses
Most proximal tibial implants are modifications of constrained total knee arthroplasty designs to compensate for the loss of stabilizing soft tissues. Difficulties encountered include a high infection and loosening rate and problems with attaching the patellar tendon to the implant. The fact that most endoprostheses are significantly less bulky than the resected proximal tibia is a major advantage. Grimer et all7 reviewed their experience of 151 custom-made endoprostheses. The first 95 prostheses were based on a fixed hinge, and the following 56 prostheses were based on a rotating-hinge knee. All were cemented. Initially the patellar tendon was reconstructed with a synthetic braided ligament passed through holes in the implant. This reconstruction caused local irritation and eventually failed, and now the tendon is repaired directly to the gastrocnemius flap. The infection rate was reduced from 36% to 12% by the introduction of routine gastrocnemius flap cover. Grimer et all7suggested that the rotating hinge has a lower failure rate than the simple hinge but could not draw firm conclusions. In a review of 245 replacements, Unwin et a156noted that the probability of a proximal tibial endoprosthesis surviving aseptic loosening was
As in the distal femur, stability of the knee depends on accurate and secure soft tissue reconstruction at surgery, including the posterior capsule, collateral ligaments, patellar tendon, and retinaculum. Some workers routinely repair or reconstruct the cruciate ligaments using allograft tendon, but others do not.6,12,25 Late instability can follow subchondral collapse. Insensitivity of the joint contributes to this instability.6 Clohisy and Mankin12reported the outcomes of 16 osteoarticular reconstructions of the proximal tibia. One patient with a peripheral neuropathy and allograft fracture had an unstable reconstruction and had to undergo amputation. At 7 years’ follow-up, 7 of 16 allografts had not survived, and the most common complicationwas structural failure of the graft. Hornicek et alB reported instabilityin 5 of 38 patients treated with a proximal tibial allograft by bracing or total knee arthroplasty. Brien et a16 compared 17 allograft reconstructions with a historical series of endoprosthetic reconstructions. Of reconstructions, 8 were osteochondral, and 7 were intercalary allografts. Brien et a16found a high rate of complications with both techniques but did not favor either. These workers reported that mild instability is common, despite extensive soft tissue repair at surgery.
708
GERRAND et a1
Authors' Preferred Approach. After resection of the proximal tibia, the authors use an endoprosthesisbecause of its smaller bulk. The authors routinely use a medial gastrocnemius flap. The patellar tendon is fixed to the implant using a polyethylene clamp and is sutured into the flap. On occasion, the authors have been able to preserve the anterior tibia and the insertion of the patellar tendon (Fig. 11). PATELLOFEMORAL JOINT There is considerable potential for patellar problems after resections around the knee. Soft tissue resection may lead to maltracking,
devascularization, and denervation of the patella. Although some workers always resurface the patella, most do not unless the articular surface has been excised as part of the procedure?, 14,37 Patellar replacement has a significant complication rate and does not appear to influence the functional score." It may be important to maintain the height of the patella in relation to the knee joint, especially after a proximal tibial allograft? There are few reports of patellofemoral instability in the literature, but it has been described after reconstruction in relation to malunion of a distal femoral allograft.22 Eckhardt et all4 described 1 patient with lateral dislocation after resurfacing, successfully treated by medial imbrication, lateral release, and medial transfer of the patellar tendon. Other authors described patellofemoral pain treated conservatively or by revision. There is 1 report of patellofemoral impingement, although the details are not clear?,28*50 Authors' Preferred Approach. The authors do not resurface the patella routinely unless patellofemoral malalignment is present that might be improved by resurfacing, or the patella does not fit the prosthesis well. Even after an extra-articular resection, the authors try to avoid resurfacing because the bone often is thin, devascularized, and at risk of fracture. The authors have had 1 unusual complication in which a patellar button became loose and caused thrombosis of the popliteal artery (Fig. 12). TOTAL FEMORAL REPLACEMENT
Figure 11. This 37-year-oldman had resection of the proximal tibia for chondrosarcoma. A geometric excision was performed preserving the tibial tuberosity.
Occasionally, resection of the whole femur is required if malignancy extends far enough within it that a safe oncologic margin or stable reconstruction cannot be obtained. Alternatively, total femoral replacement may be indicated after revision of a partial replacement for local recurrence or loosening resulting in loss of bone stock. Some older prostheses did not have an articulating knee, but most contemporary implants do.43The risk of instability is increased because all of the soft tissues attached to the femur are released. In a series of 21 total femoral replacements reported by Ward et al,57there were 2 hip dislocations, including one that involved a 180" rotation of the implant around its long axis. The authors have not had significant problems with instability after total femoral replacement but are convinced that reattachment of the trochanter
INSTABILITY AFTER MAJOR TUMOR RESECTION
Figure 12. A 19-year-old man underwent extraarticular resection and patellar resurfacing for osteosarcoma of the distal femur. Nine years later, the patellar component displaced resulting in acute limb ischaemia.
is important for stability and abductor function (see Fig. 9).
References 1. Aboulafia AJ, Buch R, Mathews J, et al: Reconstruction using the saddle prosthesis following excision of primary and metastatic periacetabular tumors. Clin Orthop 314:203-213,1995 2. Abudu A, Grimer RJ, Cannon SR, et a1 Reconstruction of the hemipelvis after the excision of malignant tumours: Complications and functional outcome of prostheses. J Bone Joint Surg Br 79:773-779,1997 3. Aho AJ, Ekfors T, Dean PB, et a1 Incorporation and clinical results of large allografts of the extremities and pelvis. Clin Orthop 307:200-213,1994 4. Bell RS, Davis A, Allan DG, et a 1 Fresh osteochondral allografts for advanced giant cell tumors at the knee. J Arthroplasty 9:603409,1994 5. Bell RS, Davis AM, Wunder JS, et a1 Allograft reconstruction of the acetabulum after resection of stage-IIB sarcoma: Intermediate-term results. J Bone Joint Surg Am 79:1663-1674,1997 6. Brien EW, Terek RM, Healey JH, et a1 Allograft reconstruction after proximal tibia1 resection for bone tumors: An analysis of function and outcome comparing allograft and prosthetic reconstructions. Clin Orthop 303116-127,1994 7. Campanacci M, Capanna R Pelvic resections: The Rizzoli Institute experience. Orthop Clin North Am 22:65-86, 1991 8. Cannon SR Massive prostheses for malignant bone
709
tumours of the limbs. J Bone Joint Surg Br 79:497-506, 1997 9. Capanna R, Morris HG, Campanacci D, et al: Modular uncemented prosthetic reconstruction after resection of tumours of the distal femur. J Bone Joint Surg Br 76178-186,1994 10. Choong PF, Sim FH: Limb-sparing surgery for bone tumors: New developments. Semin Surg Oncol13:6469,1997 11. Choong PF, Sim FH, Pritchard DJ, et al: Megaprostheses after resection of distal femoral tumors: A rotating hinge design in 30 patients followed for 2-7 years. Acta Orthop Scand 67345351,1996 12. Clohisy DR, Mankin HJ: Osteoarticular allografts for reconstruction after resection of a musculoskeletal tumor in the proximal end of the tibia. J Bone Joint Surg Am 76:549-554,1994 13. de Meulemeester FR, Taminiau A H Saddle prosthesis after resection of a para-acetabular chondrosarcoma: A case report. Acta Orthop Scand 60363-364,1989 14. Eckardt JJ, Eilber FR, Rosen G, et al: Endoprosthetic replacement for stage IIB osteosarcoma. CGn Orthop 270202-213,1991 15. Gebhardt MC, Flugstad DI, Springfield DS, et a1 The use of bone allografts for limb salvage in high-grade extremity osteosarcoma. Clin Orthop 270:181-196,1991 16. Gradinger R, Rechl H, Hipp E: Pelvic osteosarcoma: Resection, reconstruction, local control, and survival statistics. Clin Orthop 270149-158,1991 17. Grimer RJ, Carter SR, Tillman RM, et a1 Endoprosthetic replacement of the proximal tibia [abstr]. J Bone Joint Surg Br 81:488-494,1999 18. Guest CB, Bell RS, Davis A, et a 1 Allograft-implant composite reconstruction following periacetabular sarcoma resection. J Arthroplasty 5(suppl):S25S34, 1990 19. Haentjens P, de Neve W, Casteleyn PP, et al: Massive resection and prosthetic replacement for the treatment of metastases of the trochanteric and subtrochanteric femoral region bipolar arthroplasty versus total hip arthroplasty. Acta Orthop Belg 59(suppl 1):367-371, 1993 20. Haentjens P, de Neve W, Opdecam P: [Prosthetic replacement for pathological fractures of the proximal end of the femur: Total prosthesis or bipolar arthroplasty?]. Rev Chir Orthop Reparatrice Appar Mot 80493-502,1994 21. Harrington KD, Johnston JO, Kaufer HN, et al: Limb salvage and prosthetic joint reconstruction for lowgrade and selected high-grade sarcomas of bone after wide resection and replacement by autoclaved [corrected] autogeneic grafts [published erratum appears in Clin Orthop 216:312, 1987. Clin Orthop 211:180-214,1986 22. Harris AI, Gitelis S, Sheinkop MB, et a1 Allograft prosthetic composite reconstruction for limb salvage and severe deficiency of bone at the knee or hip. Semin Arthroplasty 523594,1994 23. Hejna MJ, Gitelis S Allograft prosthetic composite replacement for bone tumors. Semin Surg Oncol 13:1824,1997 24. Hornicek FJ, Gebhardt MC, Sorger JI, et a1 Tumor reconstruction. Orthop Clin North Am 30:673-684,1999 25. Hornicek FJ Jr, Mnaymneh W, Lackman RD, et a1 Limb salvage with osteoarticular allografts after resection of proximal tibia bone tumors. Clin Orthop 352179-186, 1998 26. Horowitz SM, Glasser DB, Lane JM, et al: Prosthetic and extremity survivorship after limb salvage for
710
GERRAND et a1
sarcoma: How long do the reconstructions last? Clin Orthop 293:280-286,1993 27. Horowitz SM, Lane JM, Otis JC, et a1 Prosthetic arthropla’sty of the knee after resection of a sarcoma in the proximal end of the tibia: A report of sixteen cases. J Bone Joint Surg Am 73:28&293,1991 28. Hsu RW, Sim Fw,Chao EY Reoperation results after segmental prosthetic replacement of bone and joint for limb salvage. J Arthroplasty 14519-526,1999 29. Jofe MH, Gebhardt MC, Tomford WW, et a1 Reconstruction for defects of the proximal part of the femur using allograft arthroplasty. J Bone Joint Surg Am 70507-516,1988 30. Kabukcuoglu Y, Grimer RJ, Tillman RM, et a1 Endoprosthetic replacement for primary malignant tumors of the proximal femur. Clin Orthop 358:s-14,1999 31. Karaharju EO, Korkala OL Resection of large tumors of the anterior pelvic ring while preserving functional stability of the hip. Clin Orthop 195:270-274,1985 32. Kawai A, Muschler GF, Lane JM, et a1 Prosthetic knee replacementafter resection of a malignant tumor of the distal part of the femur: Medium to long-term results. J Bone Joint Surg Am 80:636447,1998 33. Kusuzaki K, Shinjo H, Kim W, et al: Resection hip arthroplasty for malignant pelvic tumor: Outcome in 5 patients followed more than 2 years. Acta Orthop Scand 69:617-621,1998 34. Lan F, Wunder JS, Griffin AM, et a1 Measurement of periprosthetic bone remodelling around distal femur tumor prostheses with dual energy x-ray absorptiometry (DEXA) scans. J Bone Joint Surg Br 82:120-125, 2000 35. Langlais F, Vielpeau C: Allografts of the hemipelvis after tumour resection: Technical aspects of four cases. J Bone Joint Surg Br 71:5&62,1989 36. Leung PC: Reconstruction of the pelvic ring after tumour resection. Int Orthop 16:16%171,1992 37. Malawer MM, Chou LB Prosthetic survival and clinical results with use of large-segment replacements in the treatment of high-grade bone sarcomas.J Bone Joint Surg Am 7711541165,1995 38. Malkani AL, Settecerri JJ, Sim FH, et al: Long-term results of proximal femoral replacement for nonneoplastic disorders. J Bone Joint Surg Br 77:351-356, 1995 39. Masterson EL, Ferracini R, Griffin AM, et al: Capsular replacement with synthetic mesh: Effectiveness in preventing postoperative dislocation after wide resection of proximal femoral tumors and prosthetic reconstruction. J Arthroplasty 132360-866,1998 40. McGoveran BM, Davis AM, Gross AE, et a 1 Evaluation of the allograft-prosthesis composite technique for proximal femoral reconstruction after resection of a primary bone tumour. Can.J Surg 42:3745, 1999 41. Mnaymneh W, Malinin TI, Lackman RD, et al: Massive distal femoral osteoarticular allografts after resection of bone tumors. Clin Orthop 303:103-115,1994 42. Morris HG, Capanna R, Del Ben M, et al: Prosthetic
reconstruction of the proximal femur after resection for bone tumors. J Arthroplasty 10:293-299,1995 43. Nerubay J, Katznelson A, Tichler T, et a1 Total femoral replacement. Clin Orthop 229:14>148,1988 44.Nielsen HK, Veth RP, Oldhoff J, et a1 Resection of a periacetabular chondrosarcoma and reconstruction of the pelvis: A case report. J Bone Joint Surg Br 67413-415, 1985 45. 0Connor M I Malignant pelvic tumors: Limb-sparing resection and reconstruction. Semin Surg Oncol13:4954,1997 46. 0 Connor MI, Sim FH: Salvage of the limb in the treatment of malignant pelvic tumors. J Bone Joint Surg Am 71:481494,1989 47. Ozaki T, Hillmann A, Bettin D, et a1 High complication rates with pelvic allografts: Experience of 22 sarcoma resections. Acta Orthop Scand 67333-338,1996 48. Porsch M, Kornhuber B, Hovy L: Functional results after partial pelvic resection in Ewing’s sarcoma of the ilium. Arch Orthop Trauma Surg 119:199-204,1999 49. Renard AJ, Veth RP, Schreuder HW,et a1 Revisions of endoprosthetic reconstructions after limb salvage in musculoskeletal oncology. Arch Orthop Trauma Surg 117125131,1998 50. Shin DS, Weber KL, Chao EY, et a 1 Reoperation for failed prosthetic replacement used for limb salvage. Clin Orthop 358:53-63,1999 51. Sim FH, Bowman WE Jr, Wilkins RM, et al: Limb salvage in primary malignant bone tumors. Orthopedics 83574-581,1985 52. Simon MA: Limb salvage for osteosarcoma. J Bone Joint Surg Am 70:307-310,1988 53. Springfield DS: Allograft reconstructions. Semin Surg Oncol13:11-17,1997 54. Thomas IH, Cole WG, Waters KD, et a1 Function after partial pelvic resection for Ewing’s sarcoma. J Bone Joint Surg Br 69:271-275,1987 55. Uchida A, Myoui A, Araki N, et a 1 Prosthetic reconstruction for periacetabular malignant tumors. Clin Orthop 326:23&245,1996 56. Unwin PS, Cannon SR, Grimer RJ, et a1 Aseptic loosening in cemented custom-made prosthetic replacements for bone tumours of the lower limb. J Bone Joint Surg Br 78513,1996 57. Ward WG, Dorey F, Eckardt JJ: Total femoral endoprosthetic reconstruction. Clin Orthop 316:195-206,1995 58. Windhager R, Karner J, Kutschera HP, et a 1 Limb salvage in periacetabular sarcomas: Review of 21 consecutive cases. Clin Orthop 331:265-276,1996 59. Wirganowicz PZ, Eckardt JJ, Dorey FJ, et al: Etiology and results of tumor endoprosthesis revision surgery in 64 patients. Clin Orthop 358:64-74,1999 60. Zatsepin ST, Burdygin V N Replacement of the distal femur and proximal tibia with frozen allografts. Clin Orthop 303:95-102,1994 61. Zehr RJ, Enneking WF, Scarborough MT: Allograftprosthesis composite versus megaprosthesis in proximal femoral reconstruction. Clin Orthop 322:207-223, 1996
Address reprint requests to Robert S. Bell, MD, MSc, FRCSC The University Musculoskeletal Oncology Unit Mount Sinai Hospital, Suite 476 Toronto, Ontario, M5G 1x5 Canada