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Distal Femoral Allograft Reconstruction for Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty
The Journal of Arthroplasty Vol. 21 No. 2 2006
Distal Femoral Allograft Reconstruction for Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty Hari P. Bezwada, MD,* Anjan R. Shah, MD,y Kimberly Zambito, MD,y Douglas L. Cerynik, MD,y and Norman A. Johanson, MDy
Abstract: Massive osteolytic bone loss in revision total knee arthroplasty has been an uncommon challenge. From 2001 to 2002, 11 knees in 10 patients underwent revision of failed modular PFC (Johnson and Johnson Orthopaedics, Raynham, Mass) total knee arthroplasties with distal femoral allografts and long-stemmed revision implants for massive osteolytic induced femoral bone loss. The mean followup was 42 months (range, 36-48 months). Radiographic graft incorporation was demonstrated in all 11 knees with no cases of loosening. The Knee Society Pain Scores improved by an average of 25.4 points, and the function scores improved by an average of 23.3 points. The outcomes of distal femoral allografts in the reconstruction of massive osteolytic bone loss associated with failed modular PFC (Johnson and Johnson Orthopaedics) total knee arthroplasties are favorable. Key words: allograft, osteolysis, revision total knee arthroplasty, polyethylene wear. n 2006 Elsevier Inc. All rights reserved.
sheet processor, finishing method, and shelf age [4]. Fehring et al [5], described an incidence of early failures of 7% from osteolysis or wear with a mean time in situ of 41.4 months. Recent studies have sought to determine the cause of osteolysis with more recently designed PFC modular knee implants. Because of multiple manufacturing changes, no single factor can be isolated as the cause of osteolysis in the newer designs, although changes in resin materials, radiation doses, and finishing processes appear to contribute [4]. An additional factor that has been shown to contribute to the development of osteolysis is the design of snap-fit polyethylene inserts with inadequate tibial tray locking mechanisms. This may result in substantial micromotion leading to back-side wear, the generation of polyethylene/ metallic debris, and substantial osteolysis [1,6-8]. Stockley and Gross [9] have previously described classifying large osteolytic lesions as either contained or uncontained defects. Contained defects have an intact rim of cortical bone and can be treated with cement or morselized bone graft if the defect is minimal in size [9,11]. Uncontained defects demonstrate a segmental loss of bone with
Osteolytic bone loss of the distal femur has become an increasingly common occurrence when using modular tibial components such as those used in the PFC total knee system (Johnson and Johnson Orthopaedics, Raynham, Mass) [1]. Although the favorable long-term survivorship of primary total knee arthroplasty using an early design of the PFC system has been previously published, cases of osteolysis continue to be reported [2]. Cadambi et al [3] reported an 11.1% incidence of femoral osteolysis with cementless prostheses. The factors associated with femoral osteolysis included male sex, younger age, increased weight, associated tibial osteolysis, osteoarthritis, and length of time in situ [3]. Additional factors include the polyethylene From the *Penn Orthopaedics, Pennsylvania Hospital, Philadelphia, Pennsylvania, and y Department of Orthopaedic Surgery, Drexel University College of Medicine, Philadelphia, Pennsylvania. Submitted November 12, 2004; accepted June 9, 2005. No benefits or funds were received in support of the study. Reprint requests: Hari P. Bezwada, MD, Penn Orthopaedics, Pennsylvania Hospital, 800 Spruce Street, Philadelphia, PA 19107. n 2006 Elsevier Inc. All rights reserved. 0883-5403/06/1906-0005$32.00/0 doi:10.1016/j.arth.2005.06.005
242
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 243
no remaining cortex, which can be circumferential or noncircumferential. Typically, in the femur, uncontained defects less than 1 cm in size can be treated with primary total knee components alone, whereas defects greater than 1 cm in size are best treated with structural grafts or revision knee implants [10,11]. Engh and Parks [12,13] have described the Anderson Orthopaedic Research Institute classification system for evaluation and treatment of metaphyseal bone defects. Type I defects have intact metaphyseal bone and can be reconstructed with autologous bone graft or cement and primary knee implants. Type II defects have moderately deficient metaphyseal bone and need to be reconstructed with augments or wedges and revision knee implant. Type III defects have severely deficient metaphyseal bone and will require bulk allografting and long-stemmed revision implants, custom implants, or tumor prostheses. In cases with massive osteolytic bone loss of the distal femur where the bony defect extends through the metaphyseal cancellous bone, femoral allografts may provide several advantages, including the following:(1) biocompatibility, (2) the ability to intraoperatively customize the shape of the graft to fit the defect, (3) restoration of bone stock, (4) potential for ligament reattachment, and (5) relative cost-effectiveness when compared with custom implants [14,15]. When combined with long-stemmed revision prostheses, bulk allografts have been shown to be successful for the reconstruction of massive bone defects encountered during revision surgery [15-17]. However, controversy regarding the most reliable method of implant fixation continues. Many authors advocate cementing of the allograft to the prosthesis and then press-fitting the composite into the host using cementless stems [18-22]. Cementing the femoral stem to the host without a plug or contemporary pressurization technique has been reported by Engh et al [17]. Murray et al [23] have described pressurized cementing of the femoral stem to the host femur in revision knee surgery. The purpose of this study is to review the clinical and radiographic results of revision knee arthroplasty associated with massive osteolytic bone loss that is reconstructed with distal femoral allograft and cemented long-stemmed implants.
ponents (Johnson and Johnson Orthopaedics), developed massive distal femoral osteolysis requiring revision total knee arthroplasty. Distal femoral allografts with cemented long-stemmed components were used to reconstruct massive femoral bone defects (Fig. 1A, B). Of the 10 patients, 3 were women and 7 were men; 1 man required staged bilateral revision knee arthroplasty. The mean age at the time of index surgery was 64 years (range, 52-78 years). The mean time to revision of the index arthroplasty was 6 years (range, 5-8 years). The mean age at revision surgery was 71 years (range, 58-82 years) (Table 1). All 11 knees have been followed up for a minimum of 36 months (range, 36-48 months). For 9 of 10 patients (1 knee), this was the first revision operation. For 1 patient, an initial arthroplasty was performed in 1986, and all components were revised with the Johnson and Johnson PFC revision total knee system (Johnson and Johnson Orthopaedics) in 1997 for aseptic mechanical failure of the tibial component without any evidence of femoral osteolysis at that time. The Anderson Orthopaedic Research Institute bone defect classification system was used to classify femoral and tibial bone defects on all preoperative radiographs [12]. All knees were found to have type III femoral bone defects and type I tibial defects by preoperative radiographic evaluation and were confirmed intraoperatively. All femoral defects were identified as contained defects of the femur intraoperatively. The Optetrak (Exactech, Gainsville, Fla) constrained condylar total knee system was used in 10
Materials and Methods Between March 2001 and April 2002, a series of 10 patients with 11 primary PFC posterior stabilized total knee arthroplasties with modular tibial com-
Fig. 1. A and B, Preoperative anteroposterior and lateral radiographs of a right knee demonstrating a massive, contained osteolytic defect 6 years after the index arthroplasty.
Exactec Exactec Exactec Exactec Exactec Exactec Sigma PFC Exactec Exactec 66 74 82 58 59 69 79 67 75 Range (58-82) 7 7 5 6 7 6 5 8 6 (Average 6.33) 1994 1994 1996 1995 1995 1995 1997 1994 1996 1 1 1 1 1 1 2 (1986) 1 1 R L L L R R L L R (4R, 5L) M M M M M F F M M (2F, 7M) 1 2 3 4 4 5 6 7 8
Knee Sex Patient
All revisions: revised for mechanical failure; involved grade III defects on preoperative imaging; used bulk distal femoral allografts; and fixed with cement. F/U indicates follow-up; KSKS, Knee Society Knee Score; KSFS, Knee Society Functional Score; M, male; F, female.
100 100 100 99 86 100 94 100 100 (Average 23.3) 92 71 95 85 71 30 64 100 61 99 99 100 89 97 99 97 94 99 (Average 25.4) 36 34 33 36 36 26 27 25 24 (Average 29)
90 65 85 65 74 40 77 84 64
KSFS (Preoperative) Revision Prosthesis Age at Revision (y) Years to Revision Year of Index Surgery No. of Revisions per Knee
Table 1.
Length of Stem 16 120 16 80 16 120 16 80 16 120 16 80 13 130 14 120 16 80
Duration of F/U (mo)
KSKS (Preoperative)
KSKS at Max F/U
KSFS at Max F/U
244 The Journal of Arthroplasty Vol. 21 No. 2 February 2006 knees. In one knee, which did not require a complete tibial revision, PFC sigma (Johnson and Johnson Orthopaedics) stemmed femoral component was used. All 11 knees were revised using distal femoral allografts in conjunction with cemented long-stemmed femoral implants. Statistical analysis was performed with a student t test and statistical significance was placed at the .05 level of probability. Clinical Evaluation The Knee Society Rating System was used to evaluate the patients both clinically and radiographically for the duration of follow-up. Knee Society Knee Scores and functional scores were collected by clinical examination and patient questionnaires both preoperatively and at final followup [24]. Radiographs were evaluated by the principal investigator and an independent investigator who was not involved with the revision surgery. Radiographs were evaluated for graft incorporation, graft demarcation with a radiolucent line, graft resorption, or graft collapse. The host bone cement interface was assessed for lucency, and the prosthesis was evaluated for migration and overall frontal alignment of the knee. Operative Technique A pneumatic tourniquet inflated to 350 mm of mercury was used in all cases. An anterior midline skin incision was made in line with the patient’s previous incision. Sharp dissection was than carried out to the level of the extensor mechanism without the elevation of a lateral skin flap. A median parapatellar arthrotomy was performed, and the hypertrophic synovium was excised from the suprapatellar recess and the medial and lateral gutters. The patella was mobilized, everted, and the knee flexed to 908. After a medial release, granulation tissue from around the tibial component was debrided and the tibial polyethylene liner was removed easily. In 10 of 11 revisions, substantial polyethylene wear was noted at both the articular surface and the undersurface. Delamination, cracking, and pitting of the polyethylene were also noted in these same 10 revisions. The femoral implant was then removed with a series of osteotomes, separating the implant from the underlying cement to preserve maximum bone stock (Fig. 2). After removal of the implant, the cement was more efficiently removed from the bone under direct visualization, thus exposing a large gelatinous mass of granulation tissue that filled the cavernous bone
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 245
Fig. 2. Intraoperative photograph after femoral component removal, demonstrating the previous cement mantle.
Fig. 4. Intraoperative photograph of a distal femoral bulk allograft sculpted to fit the host femoral bone defect.
defect (Fig. 3). Great care was taken to prevent any additional bone loss. The tibial component was next removed by first separating the component from the cement during removal, followed by careful removal of the cement from the bone, particularly when extracting the well-fixed cement that surrounded the tibial fins and stem. After debridement and irrigation, an extramedullary tibial cutting guide was used to make a fresh tibial cut, perpendicular to the axis of the tibial shaft. The proximal tibia was than prepared to accommodate a trapezoidal peg, and the medullary canal was reamed to fit an appropriately sized cemented modular stem. After thoroughly removing the osteolytic debris and granulation tissue from the distal femur, the femoral allograft was fashioned to fit within the cortical shell of the distal femur (Fig. 4). The structural integrity of the distal femoral cortices was severely compromised, but an effort was made to preserve
the bony envelope for the purposes of optimizing the potential for graft incorporation. The bulk allograft was impacted into place after being shaped to achieve maximal contact with the bony surfaces. Gaps between the host bone shell and distal femoral allograft were filled with cancellous bone graft. Step cuts were made in the allograft to oppose any stable platform in the host bone, usually along the posterior condylar remnant(s) and deep within the defect at the metaphyseal-diaphyseal junction. With the allograft impacted into its final stable position, the appropriate femoral cutting jigs were used to make the distal, chamfer, and intercondylar notch cuts (Fig. 5). An Optetrak (Exactech) constrained condylar total knee system was used in 10 knees, requiring a deeper notch in the distal femur. This potentially may disrupt the connection(s) between the medial and lateral femoral condyles of the allograft because of the substantial size of the housing and was a concern in small
Fig. 3. Intraoperative photograph demonstrating a massive, contained osteolytic lesion 7 years after the index arthroplasty.
Fig. 5. Intraoperative photograph of bulk allograft–host bone construct after the femoral cuts.
246 The Journal of Arthroplasty Vol. 21 No. 2 February 2006
Fig. 6. Intraoperative photograph after final component implantation (Optetrak).
femurs. This may be further jeopardized by femoral canal reaming. Distal reaming up to 18 mm was required to accommodate the stem adapter, which connected the femoral component to the modular stem. In 1 knee, which did not require a complete tibial revision, PFC sigma (Johnson and Johnson Orthopaedics) stemmed femoral component was used. A trial reduction was performed with the allograft and all trial components in place. The canals were copiously irrigated and dried, and cement restrictors were placed at the appropriate levels in the femur and tibia. The femoral and tibial prostheses were then cemented with a cement gun and pressurized into place together, if possible, with a trial tibial spacer for cement pressurization. On the femoral side, the canal cement was injected and pressurized manually before impacting the allograft into its proper position to prevent interposition of cement between host bone and the allograft. With the allograft in place, the remainder of femoral component cementing was performed in the usual fashion. (Fig. 6) Excess cement was removed and a final constrained condylar polyethylene insert was placed. Wound closure was performed in a routine fashion after hemovac drain placement. The drains were removed in 48 hours. Antibiotic prophylaxis was administered for 48 hours and low-molecular-weight heparin was used for deep venous thrombosis prophylaxis. Weight bearing was immediate and as tolerated. There were no postoperative medical complications.
preoperatively (range, 40-90) and 97 points postoperatively (range, 89-100) with a mean improvement of 25.4 points (range, 9-59) ( P b .05). Pain scores improved by an average of 14 points (range, 0-30) on a 50-point scale for a 28% overall improvement ( P b .05). Preoperative range of motion averaged 1238 (range, 1208-1258 degrees); postoperative range of motion averaged 1208 (range, 1158-1258); average decline was 38 (range, 58 to 08); and loss of range of motion was 2.4% ( P N .05). Functional scores averaged 74.3 points preoperatively (range, 30-100) and 97.6 points at final follow-up (range, 86-100) for a mean improvement of 23.3 points (range, 0-70) ( P b .05). At final follow-up, improvements were recorded in all the areas evaluated by the Knee Society Functional Score, which include walking, climbing and descending stairs, and sitting and rising from a chair. Radiographic Evaluation All 11 revisions were evaluated with serial radiographs. The 12-month postoperative followup radiographic evaluation demonstrated a stable graft-host interface in all cases. Serial radiographs, including that at final follow-up (range, 24-36 months) demonstrated no signs of graft demarcation, resorption, or host bone osteolysis (Fig. 7A, B). In addition, there were no signs of radiolucent lines at the bone cement interface surrounding the stems or migration of the implants. The overall frontal plane alignment was 58 of valgus (range, 38-88) at last radiographic evaluation.
Results Clinical Evaluation The mean knee score according to the Knee Society Clinical Rating system was 71.6 points
Fig. 7. A and B, Anteroposterior and lateral radiographs of a right knee at 36-month follow-up.
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 247
Discussion Massive osteolytic bone deficits encountered during revision total knee arthroplasty is an emerging problem that may substantially hinder a successful knee reconstruction. This cohort of patients had prior Johnson and Johnson PFC (Johnson and Johnson Orthopaedics) knee arthroplasties with modular tibial components, which have been previously implicated in association with osteolysis [4]. Fehring et al [4] concluded that the reasons for wear-related changes are most likely multifactorial and that small changes in the manufacturing and processing of poly inserts or a change in their shelfage years could adversely affect outcomes. Osteolysis has also been associated with other posterior stabilized total knee designs [25]. Collier et al [26] reported on the wear-related changes of polyethylene inserts removed during revision or autopsy and found that the shelf age of the tibial polyethylene inserts plays a significant role in the rate of tibial polyethylene wear. The use of structural allografts in revision knee arthroplasty has been reported with favorable results [15,17,27,28]. All patients in this study had a similar lesion of severe distal femoral osteolysis in which a ballooning out and severe thinning of the cortex occurred without actual loss of containment of the defect. This technique requires that the allograft is appropriately shaped for intussuception into the host bone with stable struts of host bone maximally contacting step cuts in the graft. In addition, a pressurized cement technique is described for a long-stemmed component, along with the application of bone cement at the prosthesis graft interface before implant insertion. Primary stability is important in protecting the allograft from overloading while it is ingrown by host bone. If initial stability is not achieved, then graft incorporation is less likely, and long-term durability is compromised. Some authors have recommended plate and screw fixation of the allograft in addition to invagination of the graft to ensure rotational stability [14,21,28]. Harris et al [28] recommended compression plate fixation in heavier patients and for instances in which stem fixation may be limited. Avoiding the use of plate fixation decreases the need for extensive soft tissue dissection and may decrease the risk of infection by preserving the soft tissue envelope. In addition, multiple drill holes produce channels within the allograft that may allow revascularization and possible early failure of the allograft [15]. The authors’ technique, intussuception of the graft into the host bone with preservation of surrounding soft
tissue including the blood supply to the remaining cortical shell, provided axial and rotational stability without compromising graft integrity. It has been suggested that as the graft incorporates, it transiently loses strength, increasing the risk of allograft collapse or fracture [11,27]. Others believe that the massive allografts composed of cortical bone are unlikely to be replaced with host bone during the lifetime of the recipient [15,17,29]. The tolerance of the composite to fatigue appears to be enhanced if the allograft is supported by the implant. The implant is commonly cemented to the allograft to provide stable support and fixation [28]. The use of a long intramedullary stem reduces the load across the graft and reduces the risk of subsidence, trabecular fatigue, and graft failure [17,28]. The authors’ technique involves press fitting the allograft into the host bone shell and providing a fixed support by cementing the allograft to the implant and the stem to the host femoral bone. The graft is then compressed into the host bone and held firmly by the cemented stem while further excessive compressive loads at the graft-host junction are controlled. The authors believe that this will ultimately prevent long-term graft failure. Given the materials and design of constrained femoral components, the graft-host junction may be difficult to accurately quantify using conventional radiographs. However, it is possible to observe callus formation and trabeculae crossing at the junction of the allograft and host bone. This technique uniformly achieved some radiographic indication of graft incorporation. In summary, the authors’ technique involved sculpting and intussuception of the allograft into host bone–contained defects caused by severe osteolysis. The press-fit allograft was stabilized by a pressurized cemented long-stemmed femoral component. This study demonstrated that close apposition of the allograft to host bone, along with maximal proximal fixation of the implant, provided a stable, durable construct for graft integrity and ultimate radiographic incorporation.
References 1. Engh GA, Lounici S, Rao AR, et al. In vivo deterioration of tibial baseplate locking mechanisms in contemporary modular total knee components. J Bone Joint Surg 2001;83A:1660. 2. Schai PA, Thornhill TS, Scott RD. Total knee arthroplasty with the PFC system. Results at a minimum of ten years and survivorship analysis. J Bone Joint Surg 1998;80B:850.
248 The Journal of Arthroplasty Vol. 21 No. 2 February 2006 3. Cadambi A, Engh GA, Dwyer KA, et al. Osteolysis of the distal femur after total knee arthroplasty. J Arthroplasty 1994;9:579. 4. Fehring TK, Murphy JA, Hayes TD, et al. Factors influencing wear and osteolysis in PFC modular total knees. J Arthroplasty 2004;19:256. 5. Fehring TK, Odum S, Griffin WL, et al. Early failures in total knee arthroplasty. Clin Orthop 2001;392:315. 6. Kilgus DJ, Moreland JR, Finerman GA, et al. Catastrophic wear of tibial polyethylene inserts. Clin Orthop 1991;273:223. 7. Engh GA, Dwyer KA, Hanes CK. Polyethylene wear of metal-backed tibial components in total and unicompartmental knee prostheses. J Bone Joint Surg 1992;74B:9. 8. Wasielewski RC, Parks N, Williams I, et al. Tibial insert undersurface as a contributing source of polyethylene wear debris. Clin Orthop 1997;345:53. 9. Stockley I, Gross AE. Allograft reconstruction in total knee arthroplasty. In: Czitrom AA, Gross AE, editors. Allografts in orthopaedic practice. Baltimore: Williams and Wilkins; 1992. p. 175. 10. Stockley I, McAuley JP, Gross AE. Allograft reconstruction in total knee arthroplasty. J Bone Joint Surg 1992;74B:393. 11. Ghazavi MT, Stockley I, Yee G, et al. Reconstruction of massive bone defects with allograft in revision total knee arthroplasty. J Bone Joint Surg 1997; 79A:17. 12. Engh GA. Bone defect classification. In: Engh GA, Rorabeck CH, editors. Revision total knee arthroplasty. Baltimore: Williams and Wilkins; 1997. p. 63. 13. Engh GA, Parks NL. The use of a bone defect classification system in revision total knee arthroplasty. Orthop Trans 1995;18:1138. 14. Mnaymneh W, Emerson RH, Borja F, et al. Massive allografts in salvage revisions of failed total knee arthroplasties. Clin Orthop 1990;260:144. 15. Clatworthy MG, Ballance J, Brick GW, et al. The use of structural allograft for uncontained defects in revision total knee arthroplasty. A minimum fiveyear review. J Bone Joint Surg 2001;83A:404. 16. Sculco TP, Choi JC. The role and results of bone grafting in revision total knee replacement. Orthop Clin North Am 1998;29:339.
17. Engh GA, Herzwurm PJ, Parks NL. Treatment of major defects of bone with bulk allografts and stemmed components during total knee arthroplasty. J Bone Joint Surg 1997;79A:1030. 18. Chandler HP. Revision total knee arthroplasty— structural bone grafting: when and how. Orthopedics 1996;19:797. 19. Gross AE. Revision total knee arthroplasty of bone grafts versus implant supplementation. Orthopedics 1997;20:843. 20. Dennis DA. The structural allograft composite in revision total knee arthroplasty. J Arthroplasty 2002;7(Suppl 1):90. 21. Tsahakis PJ, Beaver WB, Brick GW. Technique and results of allograft reconstruction in revision total knee arthroplasty. Clin Orthop 1994;303:86. 22. Haas SB, Insall JN, Montgomery III W, et al. Revision total knee arthroplasty with use of modular components with stems inserted without cement. J Bone Joint Surg 1995;77A:1700. 23. Murray PB, Rand JA, Hanssen AD. Cemented longstem revision total knee arthroplasty. Clin Orthop 1994;309:116. 24. Insall JN, Dorr LD, Scott RD, et al. Rationale of the knee society clinical rating system. Clin Orthop 1989;248:13. 25. O’Rourke MR, Callaghan JJ, Goetz DD, et al. Osteolysis associated with a cemented modular posterior-cruciate–substituting total knee design. J Bone Joint Surg 2002;84A:1362. 26. Collier MB, Engh CA, McAuley JP, et al. Factors associated with tibial polyethylene wear in total knee arthroplasty: analysis of inserts retrieved at revision and autopsy. J Arthroplasty 2004;19:257. 27. Rorabeck CH, Smith PN. Results of revision total knee arthroplasty in the face of significant bone deficiency. Orthop Clin North Am 1998; 29:361. 28. Harris AI, Poddar S, Gitelis S, et al. Arthroplasty with a composite of an allograft and a prosthesis for knees with severe deficiency of bone. J Bone Joint Surg 1995;77A:373. 29. Parks NL, Engh GA. Histology of nine structural bone grafts used in total knee arthroplasty. Clin Orthop 1997;345:17.
Distal Femoral Allograft Reconstruction for Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty Hari P. Bezwada, MD,* Anjan R. Shah, MD,y Kimberly Zambito, MD,y Douglas L. Cerynik, MD,y and Norman A. Johanson, MDy
Abstract: Massive osteolytic bone loss in revision total knee arthroplasty has been an uncommon challenge. From 2001 to 2002, 11 knees in 10 patients underwent revision of failed modular PFC (Johnson and Johnson Orthopaedics, Raynham, Mass) total knee arthroplasties with distal femoral allografts and long-stemmed revision implants for massive osteolytic induced femoral bone loss. The mean followup was 42 months (range, 36-48 months). Radiographic graft incorporation was demonstrated in all 11 knees with no cases of loosening. The Knee Society Pain Scores improved by an average of 25.4 points, and the function scores improved by an average of 23.3 points. The outcomes of distal femoral allografts in the reconstruction of massive osteolytic bone loss associated with failed modular PFC (Johnson and Johnson Orthopaedics) total knee arthroplasties are favorable. Key words: allograft, osteolysis, revision total knee arthroplasty, polyethylene wear. n 2006 Elsevier Inc. All rights reserved.
sheet processor, finishing method, and shelf age [4]. Fehring et al [5], described an incidence of early failures of 7% from osteolysis or wear with a mean time in situ of 41.4 months. Recent studies have sought to determine the cause of osteolysis with more recently designed PFC modular knee implants. Because of multiple manufacturing changes, no single factor can be isolated as the cause of osteolysis in the newer designs, although changes in resin materials, radiation doses, and finishing processes appear to contribute [4]. An additional factor that has been shown to contribute to the development of osteolysis is the design of snap-fit polyethylene inserts with inadequate tibial tray locking mechanisms. This may result in substantial micromotion leading to back-side wear, the generation of polyethylene/ metallic debris, and substantial osteolysis [1,6-8]. Stockley and Gross [9] have previously described classifying large osteolytic lesions as either contained or uncontained defects. Contained defects have an intact rim of cortical bone and can be treated with cement or morselized bone graft if the defect is minimal in size [9,11]. Uncontained defects demonstrate a segmental loss of bone with
Osteolytic bone loss of the distal femur has become an increasingly common occurrence when using modular tibial components such as those used in the PFC total knee system (Johnson and Johnson Orthopaedics, Raynham, Mass) [1]. Although the favorable long-term survivorship of primary total knee arthroplasty using an early design of the PFC system has been previously published, cases of osteolysis continue to be reported [2]. Cadambi et al [3] reported an 11.1% incidence of femoral osteolysis with cementless prostheses. The factors associated with femoral osteolysis included male sex, younger age, increased weight, associated tibial osteolysis, osteoarthritis, and length of time in situ [3]. Additional factors include the polyethylene From the *Penn Orthopaedics, Pennsylvania Hospital, Philadelphia, Pennsylvania, and y Department of Orthopaedic Surgery, Drexel University College of Medicine, Philadelphia, Pennsylvania. Submitted November 12, 2004; accepted June 9, 2005. No benefits or funds were received in support of the study. Reprint requests: Hari P. Bezwada, MD, Penn Orthopaedics, Pennsylvania Hospital, 800 Spruce Street, Philadelphia, PA 19107. n 2006 Elsevier Inc. All rights reserved. 0883-5403/06/1906-0005$32.00/0 doi:10.1016/j.arth.2005.06.005
242
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 243
no remaining cortex, which can be circumferential or noncircumferential. Typically, in the femur, uncontained defects less than 1 cm in size can be treated with primary total knee components alone, whereas defects greater than 1 cm in size are best treated with structural grafts or revision knee implants [10,11]. Engh and Parks [12,13] have described the Anderson Orthopaedic Research Institute classification system for evaluation and treatment of metaphyseal bone defects. Type I defects have intact metaphyseal bone and can be reconstructed with autologous bone graft or cement and primary knee implants. Type II defects have moderately deficient metaphyseal bone and need to be reconstructed with augments or wedges and revision knee implant. Type III defects have severely deficient metaphyseal bone and will require bulk allografting and long-stemmed revision implants, custom implants, or tumor prostheses. In cases with massive osteolytic bone loss of the distal femur where the bony defect extends through the metaphyseal cancellous bone, femoral allografts may provide several advantages, including the following:(1) biocompatibility, (2) the ability to intraoperatively customize the shape of the graft to fit the defect, (3) restoration of bone stock, (4) potential for ligament reattachment, and (5) relative cost-effectiveness when compared with custom implants [14,15]. When combined with long-stemmed revision prostheses, bulk allografts have been shown to be successful for the reconstruction of massive bone defects encountered during revision surgery [15-17]. However, controversy regarding the most reliable method of implant fixation continues. Many authors advocate cementing of the allograft to the prosthesis and then press-fitting the composite into the host using cementless stems [18-22]. Cementing the femoral stem to the host without a plug or contemporary pressurization technique has been reported by Engh et al [17]. Murray et al [23] have described pressurized cementing of the femoral stem to the host femur in revision knee surgery. The purpose of this study is to review the clinical and radiographic results of revision knee arthroplasty associated with massive osteolytic bone loss that is reconstructed with distal femoral allograft and cemented long-stemmed implants.
ponents (Johnson and Johnson Orthopaedics), developed massive distal femoral osteolysis requiring revision total knee arthroplasty. Distal femoral allografts with cemented long-stemmed components were used to reconstruct massive femoral bone defects (Fig. 1A, B). Of the 10 patients, 3 were women and 7 were men; 1 man required staged bilateral revision knee arthroplasty. The mean age at the time of index surgery was 64 years (range, 52-78 years). The mean time to revision of the index arthroplasty was 6 years (range, 5-8 years). The mean age at revision surgery was 71 years (range, 58-82 years) (Table 1). All 11 knees have been followed up for a minimum of 36 months (range, 36-48 months). For 9 of 10 patients (1 knee), this was the first revision operation. For 1 patient, an initial arthroplasty was performed in 1986, and all components were revised with the Johnson and Johnson PFC revision total knee system (Johnson and Johnson Orthopaedics) in 1997 for aseptic mechanical failure of the tibial component without any evidence of femoral osteolysis at that time. The Anderson Orthopaedic Research Institute bone defect classification system was used to classify femoral and tibial bone defects on all preoperative radiographs [12]. All knees were found to have type III femoral bone defects and type I tibial defects by preoperative radiographic evaluation and were confirmed intraoperatively. All femoral defects were identified as contained defects of the femur intraoperatively. The Optetrak (Exactech, Gainsville, Fla) constrained condylar total knee system was used in 10
Materials and Methods Between March 2001 and April 2002, a series of 10 patients with 11 primary PFC posterior stabilized total knee arthroplasties with modular tibial com-
Fig. 1. A and B, Preoperative anteroposterior and lateral radiographs of a right knee demonstrating a massive, contained osteolytic defect 6 years after the index arthroplasty.
Exactec Exactec Exactec Exactec Exactec Exactec Sigma PFC Exactec Exactec 66 74 82 58 59 69 79 67 75 Range (58-82) 7 7 5 6 7 6 5 8 6 (Average 6.33) 1994 1994 1996 1995 1995 1995 1997 1994 1996 1 1 1 1 1 1 2 (1986) 1 1 R L L L R R L L R (4R, 5L) M M M M M F F M M (2F, 7M) 1 2 3 4 4 5 6 7 8
Knee Sex Patient
All revisions: revised for mechanical failure; involved grade III defects on preoperative imaging; used bulk distal femoral allografts; and fixed with cement. F/U indicates follow-up; KSKS, Knee Society Knee Score; KSFS, Knee Society Functional Score; M, male; F, female.
100 100 100 99 86 100 94 100 100 (Average 23.3) 92 71 95 85 71 30 64 100 61 99 99 100 89 97 99 97 94 99 (Average 25.4) 36 34 33 36 36 26 27 25 24 (Average 29)
90 65 85 65 74 40 77 84 64
KSFS (Preoperative) Revision Prosthesis Age at Revision (y) Years to Revision Year of Index Surgery No. of Revisions per Knee
Table 1.
Length of Stem 16 120 16 80 16 120 16 80 16 120 16 80 13 130 14 120 16 80
Duration of F/U (mo)
KSKS (Preoperative)
KSKS at Max F/U
KSFS at Max F/U
244 The Journal of Arthroplasty Vol. 21 No. 2 February 2006 knees. In one knee, which did not require a complete tibial revision, PFC sigma (Johnson and Johnson Orthopaedics) stemmed femoral component was used. All 11 knees were revised using distal femoral allografts in conjunction with cemented long-stemmed femoral implants. Statistical analysis was performed with a student t test and statistical significance was placed at the .05 level of probability. Clinical Evaluation The Knee Society Rating System was used to evaluate the patients both clinically and radiographically for the duration of follow-up. Knee Society Knee Scores and functional scores were collected by clinical examination and patient questionnaires both preoperatively and at final followup [24]. Radiographs were evaluated by the principal investigator and an independent investigator who was not involved with the revision surgery. Radiographs were evaluated for graft incorporation, graft demarcation with a radiolucent line, graft resorption, or graft collapse. The host bone cement interface was assessed for lucency, and the prosthesis was evaluated for migration and overall frontal alignment of the knee. Operative Technique A pneumatic tourniquet inflated to 350 mm of mercury was used in all cases. An anterior midline skin incision was made in line with the patient’s previous incision. Sharp dissection was than carried out to the level of the extensor mechanism without the elevation of a lateral skin flap. A median parapatellar arthrotomy was performed, and the hypertrophic synovium was excised from the suprapatellar recess and the medial and lateral gutters. The patella was mobilized, everted, and the knee flexed to 908. After a medial release, granulation tissue from around the tibial component was debrided and the tibial polyethylene liner was removed easily. In 10 of 11 revisions, substantial polyethylene wear was noted at both the articular surface and the undersurface. Delamination, cracking, and pitting of the polyethylene were also noted in these same 10 revisions. The femoral implant was then removed with a series of osteotomes, separating the implant from the underlying cement to preserve maximum bone stock (Fig. 2). After removal of the implant, the cement was more efficiently removed from the bone under direct visualization, thus exposing a large gelatinous mass of granulation tissue that filled the cavernous bone
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 245
Fig. 2. Intraoperative photograph after femoral component removal, demonstrating the previous cement mantle.
Fig. 4. Intraoperative photograph of a distal femoral bulk allograft sculpted to fit the host femoral bone defect.
defect (Fig. 3). Great care was taken to prevent any additional bone loss. The tibial component was next removed by first separating the component from the cement during removal, followed by careful removal of the cement from the bone, particularly when extracting the well-fixed cement that surrounded the tibial fins and stem. After debridement and irrigation, an extramedullary tibial cutting guide was used to make a fresh tibial cut, perpendicular to the axis of the tibial shaft. The proximal tibia was than prepared to accommodate a trapezoidal peg, and the medullary canal was reamed to fit an appropriately sized cemented modular stem. After thoroughly removing the osteolytic debris and granulation tissue from the distal femur, the femoral allograft was fashioned to fit within the cortical shell of the distal femur (Fig. 4). The structural integrity of the distal femoral cortices was severely compromised, but an effort was made to preserve
the bony envelope for the purposes of optimizing the potential for graft incorporation. The bulk allograft was impacted into place after being shaped to achieve maximal contact with the bony surfaces. Gaps between the host bone shell and distal femoral allograft were filled with cancellous bone graft. Step cuts were made in the allograft to oppose any stable platform in the host bone, usually along the posterior condylar remnant(s) and deep within the defect at the metaphyseal-diaphyseal junction. With the allograft impacted into its final stable position, the appropriate femoral cutting jigs were used to make the distal, chamfer, and intercondylar notch cuts (Fig. 5). An Optetrak (Exactech) constrained condylar total knee system was used in 10 knees, requiring a deeper notch in the distal femur. This potentially may disrupt the connection(s) between the medial and lateral femoral condyles of the allograft because of the substantial size of the housing and was a concern in small
Fig. 3. Intraoperative photograph demonstrating a massive, contained osteolytic lesion 7 years after the index arthroplasty.
Fig. 5. Intraoperative photograph of bulk allograft–host bone construct after the femoral cuts.
246 The Journal of Arthroplasty Vol. 21 No. 2 February 2006
Fig. 6. Intraoperative photograph after final component implantation (Optetrak).
femurs. This may be further jeopardized by femoral canal reaming. Distal reaming up to 18 mm was required to accommodate the stem adapter, which connected the femoral component to the modular stem. In 1 knee, which did not require a complete tibial revision, PFC sigma (Johnson and Johnson Orthopaedics) stemmed femoral component was used. A trial reduction was performed with the allograft and all trial components in place. The canals were copiously irrigated and dried, and cement restrictors were placed at the appropriate levels in the femur and tibia. The femoral and tibial prostheses were then cemented with a cement gun and pressurized into place together, if possible, with a trial tibial spacer for cement pressurization. On the femoral side, the canal cement was injected and pressurized manually before impacting the allograft into its proper position to prevent interposition of cement between host bone and the allograft. With the allograft in place, the remainder of femoral component cementing was performed in the usual fashion. (Fig. 6) Excess cement was removed and a final constrained condylar polyethylene insert was placed. Wound closure was performed in a routine fashion after hemovac drain placement. The drains were removed in 48 hours. Antibiotic prophylaxis was administered for 48 hours and low-molecular-weight heparin was used for deep venous thrombosis prophylaxis. Weight bearing was immediate and as tolerated. There were no postoperative medical complications.
preoperatively (range, 40-90) and 97 points postoperatively (range, 89-100) with a mean improvement of 25.4 points (range, 9-59) ( P b .05). Pain scores improved by an average of 14 points (range, 0-30) on a 50-point scale for a 28% overall improvement ( P b .05). Preoperative range of motion averaged 1238 (range, 1208-1258 degrees); postoperative range of motion averaged 1208 (range, 1158-1258); average decline was 38 (range, 58 to 08); and loss of range of motion was 2.4% ( P N .05). Functional scores averaged 74.3 points preoperatively (range, 30-100) and 97.6 points at final follow-up (range, 86-100) for a mean improvement of 23.3 points (range, 0-70) ( P b .05). At final follow-up, improvements were recorded in all the areas evaluated by the Knee Society Functional Score, which include walking, climbing and descending stairs, and sitting and rising from a chair. Radiographic Evaluation All 11 revisions were evaluated with serial radiographs. The 12-month postoperative followup radiographic evaluation demonstrated a stable graft-host interface in all cases. Serial radiographs, including that at final follow-up (range, 24-36 months) demonstrated no signs of graft demarcation, resorption, or host bone osteolysis (Fig. 7A, B). In addition, there were no signs of radiolucent lines at the bone cement interface surrounding the stems or migration of the implants. The overall frontal plane alignment was 58 of valgus (range, 38-88) at last radiographic evaluation.
Results Clinical Evaluation The mean knee score according to the Knee Society Clinical Rating system was 71.6 points
Fig. 7. A and B, Anteroposterior and lateral radiographs of a right knee at 36-month follow-up.
Massive Osteolytic Bone Loss in Revision Total Knee Arthroplasty ! Bezwada et al 247
Discussion Massive osteolytic bone deficits encountered during revision total knee arthroplasty is an emerging problem that may substantially hinder a successful knee reconstruction. This cohort of patients had prior Johnson and Johnson PFC (Johnson and Johnson Orthopaedics) knee arthroplasties with modular tibial components, which have been previously implicated in association with osteolysis [4]. Fehring et al [4] concluded that the reasons for wear-related changes are most likely multifactorial and that small changes in the manufacturing and processing of poly inserts or a change in their shelfage years could adversely affect outcomes. Osteolysis has also been associated with other posterior stabilized total knee designs [25]. Collier et al [26] reported on the wear-related changes of polyethylene inserts removed during revision or autopsy and found that the shelf age of the tibial polyethylene inserts plays a significant role in the rate of tibial polyethylene wear. The use of structural allografts in revision knee arthroplasty has been reported with favorable results [15,17,27,28]. All patients in this study had a similar lesion of severe distal femoral osteolysis in which a ballooning out and severe thinning of the cortex occurred without actual loss of containment of the defect. This technique requires that the allograft is appropriately shaped for intussuception into the host bone with stable struts of host bone maximally contacting step cuts in the graft. In addition, a pressurized cement technique is described for a long-stemmed component, along with the application of bone cement at the prosthesis graft interface before implant insertion. Primary stability is important in protecting the allograft from overloading while it is ingrown by host bone. If initial stability is not achieved, then graft incorporation is less likely, and long-term durability is compromised. Some authors have recommended plate and screw fixation of the allograft in addition to invagination of the graft to ensure rotational stability [14,21,28]. Harris et al [28] recommended compression plate fixation in heavier patients and for instances in which stem fixation may be limited. Avoiding the use of plate fixation decreases the need for extensive soft tissue dissection and may decrease the risk of infection by preserving the soft tissue envelope. In addition, multiple drill holes produce channels within the allograft that may allow revascularization and possible early failure of the allograft [15]. The authors’ technique, intussuception of the graft into the host bone with preservation of surrounding soft
tissue including the blood supply to the remaining cortical shell, provided axial and rotational stability without compromising graft integrity. It has been suggested that as the graft incorporates, it transiently loses strength, increasing the risk of allograft collapse or fracture [11,27]. Others believe that the massive allografts composed of cortical bone are unlikely to be replaced with host bone during the lifetime of the recipient [15,17,29]. The tolerance of the composite to fatigue appears to be enhanced if the allograft is supported by the implant. The implant is commonly cemented to the allograft to provide stable support and fixation [28]. The use of a long intramedullary stem reduces the load across the graft and reduces the risk of subsidence, trabecular fatigue, and graft failure [17,28]. The authors’ technique involves press fitting the allograft into the host bone shell and providing a fixed support by cementing the allograft to the implant and the stem to the host femoral bone. The graft is then compressed into the host bone and held firmly by the cemented stem while further excessive compressive loads at the graft-host junction are controlled. The authors believe that this will ultimately prevent long-term graft failure. Given the materials and design of constrained femoral components, the graft-host junction may be difficult to accurately quantify using conventional radiographs. However, it is possible to observe callus formation and trabeculae crossing at the junction of the allograft and host bone. This technique uniformly achieved some radiographic indication of graft incorporation. In summary, the authors’ technique involved sculpting and intussuception of the allograft into host bone–contained defects caused by severe osteolysis. The press-fit allograft was stabilized by a pressurized cemented long-stemmed femoral component. This study demonstrated that close apposition of the allograft to host bone, along with maximal proximal fixation of the implant, provided a stable, durable construct for graft integrity and ultimate radiographic incorporation.
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