Osteochondral plugs: Autogenousosteochondral mosaicplasty for the treatment of focal chondral and osteochondral articular defects

OSTEOCHONDRAL PLUGS: AUTOGENOUS OSTEOCHONDRAL MOSAICPLASTY FOR THE TREATMENT OF FOCAL CHONDRAL AND OSTEOCHONDRAL ARTICULAR DEFECTS L,a,SZLO HANGODY, MD, PHD, GARY KISH, MD, ZOLTAN K,~RP,~,TI, MD and ROBERT EBERHART, MD

A new method of treating articular chondral defects and Osteochondritis Dissecans with autogenous osteochondral plugs is described. Following animal trials in 1991, the technique has been used by the authors in 204 patients in Hungary and 31 in the United States with good to excellent results based on clinical examination, follow-up arthroscop~ magnetic resonance imaging (MRI), and computed tomography (CT) scans. The procedure can be done open, or arthroscopically in the case of smaller lesions, with newly designed and commercially available instruments. The patients have been followed at set intervals and evaluated by use of modified Hospital for Special Surgery Score (HSS), Cincinnati (condylar and patella), Bandi (donor), and Hanover (talus) scoring systems. These studies show that patients improve during the first year and then retain their good to excellent scores. Nineteen biopsies from the treated femoral condyles at various intervals up to 2.5 years show progressive and consistent evidence of deep matrix integration at the recipient donor interface. KEY WORDS: autogenous osteochondral grafts, replacement of weight surface of joints, cartilage defects, matrix integration

Osteochondral grafting is not new. Over the past 50 years there have been many reports on the use of allograft and autogenous osteochondral material for the treatment of osteochondritis dissecans (OCD) and for replacement of bone defects after tumor resection. ~-5 Recently, there have been a number of reports on the use of fresh autogenous small cylindrical osteochondral plugs for the treatment of focal chondral and osteochondral defects of the femoral condyles in the knee. ~9 These preliminary reports give encouraging results and document successful treatment of lesions of the femoral condyles. The Mosaicplasty method of Hangody et al has been successful in treating lesions of the femoral condyles and the patella and OCD of the knee and the talus. ~° The method of Hangody et al was conceived in 1991 and submitted to vigorous animal trials before clinical application started on February 6, 1992.11 Since that time, 174 (154 in Budapest, 11 in Portsmouth) open cases and 61 (50 in Budapest, 11 in Portsmouth) arthroscopic cases have been performed in Budapest (B), Hungary, and Portsmouth (P), N e w Hampshire. Early results (<18 months) in the Portsmouth group show clinical results similar to the Hungarian experience. Patients tend to improve over the first

From the Department of Orthopaedics, Uzsoki Hospital, Budapest, Hungary; and the Division of Sports Medicine, University of New Hampshire, Durham, NH. Address reprint requests to Gary Kish, MD, St. George Medical, 109 Hillside Dr, Portsmouth, NH 03801. Copyright © 1997 by W.B. Saunders Company 1048-6666/97/0704-0001 $05.00/0

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year and maintain their good to excellent results over time (Fig 1).

PRECLINICAL ANIMAL TRIALS The idea of using small diameter osteochondral plugs was initiated by Hangody in early 1991 after he observed the strength and century-old durability of the wooden mosaic walkways on the shores of Lake Balaton in Hungary. t~ To create the best animal model, a working breed of dogs was selected. These dogs had been shown to generate high forces in their hind quarters, and have large enough knee joints to use the full range of graft sizes (2.7-4.5 ram). ~2The periphery of the supracondylar ridge of the distal femoral articular surface was selected as the donor site because it is relatively non-weight-bearing in quadrupeds (tess so in bipeds) yet has thick hyaline cartilage, is A number of interesting observations were made during the course of this animal study: 1. At 4 weeks, the cancellous bone between donor plugs and recipient site had united (Figs 2A and 2B). At 8 weeks, the fibrocartilage at the cartilage bone interface had grown to the surface and created a seal between the recipient and donor cartilage. Areas of matrix integration were seen even on the early biopsies (Fig 2C). 2. No subsidence was seen in the non-weight-bearing areas, but was seen in one third of weight-bearing grafts. These findings suggested that in clinical practice the joint should be kept non-weight-bearing for 6 to 8 weeks.

Operative Techniques in Orthopaedics, Vol 7, No 4 (October), 1997: pp 312-322

Fig 1. Case of OCD with long-term follow up, (A) Preoperative OCD, (B) Ten plug intraoperative medial femoral Mosaicplasty with 4.5 mm and 3,5 mm diameter cylindrical osteochondral plugs, (C) A 5-year control arthroscopy of a 10 plug Mosaicplasty. (D) A 5-year postoperative OCD graft biopsy specimen under polarized light showing the maintenance of the hyaline character of the transplanted tissue (collagen specific picro sirius red; original magnification x20), (E) At 5 years: junction of the transplanted hyaline graft and the fibrocartilage "grouting" under polarized light, No gap can be seen between the two tissues (GAG specific solution under polarized light; original magnification x20).

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313

Fig 2. (A) Donor site of dog knee at 4 weeks after transplantation. Cancellous bone growth at depth and fibrocartilage at the surface is evident, (B) At 4 weeks subchondral bone union is present. (C) At 8 weeks, evidence of early cartilage integration can be appreciated.

3. The donor sites filled in with cancellous bone and fibrocartilage that was firmly adherent to the surrounding cartilage.

METHODS AND MATERIALS With these encouraging observations and finding that the grafts retained their hyaline morphology and physical characteristics, clinical application of the Mosaicplasty technique began in February of 1992. Special instrumentation was developed to assist in obtaining and inserting the grafts. Recentl}~ the set has been expanded to include arthroscopic instruments. As the clinical experience has grown, both in the number of patients and the length of follow-up, a few tenets seem important to ensuring a satisfactory outcome: 1. Proper patient selection. The procedure is designed for the treatment of focal chondral and osteochondral defects of traumatic and vascular origin in the knee and talus in patients under the age of 45. This arbitrary upper-age limit is supported by the general observation that the quality of the articular cartilage begins to decrease in the fifth decade. 2. Patient cognitive and general physical condition need to be considered. The patient must be willing and able to remain non-weight-bearing on the affected extremity, and actively participate in the rehabilitation program. 3. Patient education. Often the focal defect is discovered at arthroscopy. When the preoperative index of suspicion 314

is high (concomitant anterior cruciate ligament [ACL] or meniscal tear, joint line tenderness in a patient 30 years of age or older), both surgeon and patient should be prepared for possible Mosaicplasty. As magnetic resonance imaging (MRI) technology continues to improve, more cartilage defects may be discovered preoperatively. The patient needs to be made aware of the potential of an open procedure if the lesion is over 1.5 cm in diameter, and of the need for postoperative weight bearing and rehabilitation.

OPERATIVE TECHNIQUE FOR FEMORAL CONDYLAR DEFECTS Patients receive preoperative intervenous (IV) antibiotics and the procedure is done with patients under general or regional anesthesia and tourniquet control. The table set up should allow for knee flexion to 120 °. Once the lesion has been identified by arthroscop~ it is measured for size. The decision is then made to proceed arthroscopically or by open technique. This decision is based on the size and location of the lesion and the experience of the surgeon. Any lesion should be treated by the open technique if it is more than 1.5 cm in diameter or if more than half of it is posterior to the center of the weight-bearing surface ("the T point"). 14 Smaller lesions can be treated by the arthroscopic technique. Because it is technically demanding, the latter method should be reserved for later cases in the surgeon's experience or after extensive laboratory training. HANGODY ET AL

B

Fig 5. A guide is used in making the drill holes. Keeping the drill perpendicular to the surface is important. In large defects, starting at the periphery and working inward is advised, (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)

Fig 3. (A) The graft is obtained with inside and outside cutting tubular chisels that are toggled, breaking the graft off at the tip, and then pulled out. (B) The grafts are gently pushed from the distal end of the tube chisel with the tamp. They are inspected for length and the slope of the cartilage cap. (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)

Open Technique In the open technique, surrounding cartilage is carefully inspected and any poor quality cartilage is debrided to a sharp stable margin. To promote fibrocartilage in-growth, a subchondral abrasion is performed. ~3 The next step is to determine the number of grafts needed, and then expose the donor site. The grafts are taken with specially designed tubular cutting chisels. When the proper depth is achieved, the chisel is toggled, effectively breaking the graft off at the tip. The chisel containing the osteochondral plug is pulled out (Fig 3A). The grafts are then removed from the chisel by tamping the distal end (Fig 3B). At this point the grafts are

Fig 4. Cartilage plugs after harvesting. The cartilage cap will assume a slightly mushroom shape. For full thickness chondral defects the length of the grafts should be 10 to 15 mm, and 15 to 25 mm for OCD lesions.

MOSAICPLASTY

inspected for length, the slope of the cartilage surface, and then stored in saline (Fig 4). Cave and Blount refractors are useful in exposing the chondral defect, as well as keeping the length of the incision to a minimum. In large OCD lesions of the posterior condyles, eversion of the patella will be necessary, or in the case of the lateral condyles, the Keblish lateral incision can be considered. ~6 The recipient site preparation now involves drilling and dilating of evenly spaced and properly sized holes. The circular and tube guides are designed to keep the holes divided by 0.3 to 1 mm. In general, the 4.5 m m holes are made first. Drill holes are usually started on the periphery of the defect and worked inward, keeping the drill bit perpendicular to the recipient surface (Fig 5). The grafts need to be inserted perpendicular to the surface to maximize congruency. Occasionally, because of the rapidly changing radii of the condyles, the holes will become confluent at depth. This usually will not present a problem. These drill holes are made 2 to 3 m m longer than the grafts

i

B

I

Fig 6. Dilation and insertion of the osteocartilage plugs. (A) The dilators taper up by 0.3 mm to the 20 mm mark. The instruments smooth out the side wails and enlarge the entrance of the tunnel, facilitating insertion of the graft. (B) The grafts can be gently tapped in by finger pressure or the tamp. (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)

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Fig 7. Case of a medial femoral condyle OCD. (A) Radiograph of a large OCD lesion of the medial femoral condyle in a 21-year-old skier who tolerated chronic pain until his knee locked up and swelled after a fall. (B) Intraoperative view: 17 grafts of various diameter have been inserted. The smaller grafts serve to fill the defect as well as lock in the larger grafts. (C) Radiograph view at 4 months showing evidence of graft incorporation.

to insure that the grafts will not sit proud. The grafts are secured by press fit, not by bottoming out. The grafts are put in as holes are drilled and dilated. This sequence is important as each new graft will influence the contour of its neighboring holes. The dilator enlarges the entrance and contours the side walls, making graft insertion smooth (Fig 6A). The 4.5 m m grafts may leave enough space at the surface for the insertion of smaller grafts, and 2.7 and 3.5 m m

grafts can be used to fill gaps to increase the hyaline surface. Finger pressure or a plastic tamp can be used to seat the grafts flush to the surrounding surface (Fig 6B). A graft that is too low can be retrieved by grasping the plug below the cartilaginous cap with smooth forceps, then slowing rotating it back to the proper level. Finally the knee is placed through a range of motion with varus or valgus. Up to 18 grafts have been inserted in this fashion (three cases to date) (Fig 7). The wound is closed over a drain, the patient kept overnight and instructed in the proper non-weight-bearing time (4-8 weeks depending on the size and location of the lesion), and followed up at regular intervals. This open technique is also appropriate for patellar and talar defects. ~°

Arthroscopic Technique

Fig 8. Newly designed arthroscopic instrumentation allows for more precise and predictable insertion of the grafts. (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)-

31 6

The arthroscopic technique differs from the open technique in the instrumentation and difficulty. Lesions of the femoral condyles < 1.5 cm in diameter can be treated arthroscopically as long as they are accessible. New instruments have been designed to make graft insertion easier and more predictable (Fig 8). The operating room set up is similar to that for the open technique and must allow for knee flexion of 120 °. Perpendicular access to the lesion is critical to the proper placement of the grafts. Care must be exercised in making the viewing and working portals. In most femoral condylar lesions, central anterior medial and central anterior lateral portals will allow adequate access. It should be noted that these portals are more central than the standard portals. The lesion is prepared arthroscopicall~ by debridement of loose cartilage and subchondral abrasion. The lesion is

HANGODYETAL

A

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Fig 9. Chisels should be placed perpendicular to both the donor and recipient surfaces, (A) The slopes of the condyles can be used as guides to keep the chisel flat to the surface and on the periphery, (B) To remain perpendicular to the surface with the chisel guide may require a large change of direction from hole to hole, This maneuvering is particularly necessary on the inner aspect of the medial femoral condyle where the radius of curvature changes rapidly over a short distance. (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)

measured with the guide chisel to determine the number of grafts required. As in the open technique, the supracondylar ridge of the distal femoral articular surface is used as a donor site. The grafts can be obtained either arthroscopically or through a mini-arthrotomy (1.5-2.0 cm). If the grafts are to be taken arthroscopically, certain steps are recommended. The grafts are taken from either medial or lateral periphery of the patellofemoral joint. The scope is introduced into the inferior ipsilateral portal and the lens angled as needed. A MOSAICPLASTY

Fig 10. Plug insertion. (A) With the guide chisel held firmly in place, the dilator is removed. The graft is delivered into the hole with the use of an adjustable plunger, The windows in the guide allow for visualization of the plug as it is being seated, (B) As the subsequent plugs are inserted, keeping the shoulder of the guide chisel off the previously inserted plug is important to avoid inadvertently pushing them in too deep. (Reprinted with permission from the Endoscopy Division of Smith and Nephew Inc, Andover, MA.)

spinal needle or Kirschner (K) wire is used to locate the donor site and the portal made. The proper sized tube chisel is introduced with the plastic tamp. The condylar slope can be used as a guide to keep the chisel flat on the surface (Fig 9A). Hold the chisel firmly to avoid skiving the articular surface and producing a crooked graft. As in the open procedure, the graft is removed for sizing and surface contouring. The donor portal or incision is closed watertight. 317

TABLE 1. Results of Arthroscopic Mosaicplasty Patient 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Age

Sex

DX

Preoperatives

Site

Operative

17 21 29 19 38 43 27 19 29 31 37 41 26 45 32 32 26 31 33 44 19 39 22 32 45 43 17 22 40 31 38 24 22 37 20 25 28 33 31 32 19 30 28 24

F F M M M F M F M F M M F M M M M M F F M M F F M M M F F M F M F F M M M M F M F M M F

CM CDT CM, ACL, MT CM, MT CM, MT CM, MT CM OCD CDT, ACL CM, MT CM OCD CM CM, MT CM CM, MT CM OCD CM, MT CM, ACL, MT CM, MT CM, ACL, MT CM, ACL CM, MT CM, MT CDT CM, ACL CM, MT CM, MT CM CM CM CM CM, ACL, MT CM CM, MT CM, ACL OCD CM, MT CDT CM, ACL CM CM, MT CM, MT

1 1,3 2, 3, 4, 5 24 13 2, 3, 4 2 13 2, 3, 5 2, 3, 4 1,3 2, 3 1 2, 3 2 1,3 1,3 2, 3 1,3 2 2, 3 2, 3, 4, 5 2, 3, 5 1,3, 4 1,3 1, 3 2, 3, 5 2, 3 2 2 1 2, 3 1,3 2, 3, 5 2, 3 1 2, 5 2, 3 1,3 1, 3 3, 5 1,3 2, 3, 4 2, 3

MFC LFC MFC MFC MRC LFC MFC MRC MFC, LFC LFC, ACL LFC MFC MFC MFC LFC MFC, ACL LFC MFC MFC LFC MFC MFC LFC MFC LFC MFC MFC LFC MFC, LFC LFC MFC, LFC MFC MFC MFC MF MRC LFC MFC, LFC MFC MFC LFC LFC MFC LFC

MP-2 MP-3 MP-2, ACL, MR MP-4, MR MP-3, MS MP-2, MS MP-4 MP-5 MP-4, ACL MP-4,MR MP-3 MP-5 MP-4 MP-2, MR MP-3 MP-4, MR MP-4 MP-5 MP-3, MS MP-3 MP-2, MS MP-4, ACL, MR MP-3, ACL MP-2, MR MP-4, MR MP-4 MP-3, ACL MP-1, MS MP-6, MR MP-4 MP-7 MP-5 MP-5 MP-4, MR, ACL MP-6 MP-2, MR MP-3, ACL MP-7 MP-3, MR MP-4 MP-1, ACL MP-4 MP-2, MS MP-3, MS

NWB

Complications

Postoperative Studies

HHS

4 4 4 4 4 4 4 4 6 4 4 6 6 2 4 6 4 6 4 3 4 4 6 3 4 4 4 3 6 4 6 4 4 4 8 3 4 6 4 4 4 4 4 4

0 0 0 0 0 0 0 H 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 CA, BX MRI, CA, BX CTA, US 0 0 0 MRI, 3D-CT 0 CT, CA, BX 0 MRI, 3D-CT 0 0 CA MRI, CTA, CA MRI MRI, CTA, CA MRI 0 0 CTA, US CA, BX CA, BX MRI 0 MRI, 3D-CT 0 MRI, US 0 CA 0 US, CTA 0 CTA 0 CA, BX 0 MRI 0 MRI CTA MRI 0

97 92 85 72 87 100 97 100 93 97 95 100 100 100 67 100 92 97 85 100 100 100 97 100 100 97 100 100 97 100 83 100 88 100 69 97 100 97 100 100 97 97 100 93

Abbreviations of diagnosis (DX): MT, meniscal tear; ACL, anterior cruciate ligament; OCD, osteochondritis dissecans; CDT, chondral defect traumatic; CM, chondromalacia Ill-IV. Key to peoperative symptoms (SX): 1, pain; 2, pain with activity; 3, swelling; 4, locking; 5, instability. Abbreviations of site: MFC, medial femoral condyle; LFC, lateral femoral condyle. Abbreviations of operation (OP): MP-4, Mosaicplasty (corresponding number of grafts); ACL, anterior cruciate ligament reconstruction; MS, meniscal suture; MR, meniscal repair. Abbreviations: NWB, non-weight-bearing (measured in weeks); Sl, superficial infection; DI, deep infection; H, hematoma; DVT, deep venous thrombosis. Abbreviations of postoperative study: CA, control arthroscopy; BX, biopsy; MRI, magnetic resonance imaging; CTA, computed tomographic arthroscopy; US, ultrasound; 3-D CT, three-dimensional computed tomography. Abbreviation of score: HSS, modified Hospital for Special Surgery score.

With the knee flexed and good distention established, the windowed guide chisel is reintroduced. It is placed in the defect perpendicular to the surface. By rotating the scope, the chisel can be seen from different angles, ensuring proper position. It is tapped into place. Even for the experienced arthroscopist, the direction of the instruments to achieve perpendicularity may be counterintuitive and will require practice (Fig 9B). The appropriately-sized pointed drill is inserted and drilled to the desired depth of 15 to 20 mm. The drill bit is removed. The dilator is then inserted through the guide chisel into the newly created hole. The dilator is particularly valuable because the saline environment causes the cancellous walls to swell. With the guide chisel firmly held, the dilator is removed. The graft is then delivered into the hole through the windowed guide chisel with the use of the adjustable plunger. The windows

318

at the end of the chisel allow for direct visualization of the graft as it is being seated. By spinning the handle of the plunger in a counterclockwise direction, the plug can be seated deeper. The inferior edge of the window is usually at the level of the articular surface and can be used as a guide (Fig 10A). If the graft is proud, it can be tamped down with the plastic tamp of appropriate size. The subsequent plugs are inserted in a similar fashion. Caution must be taken to keep the shoulder of the guiding chisel off the adjacent graft, to avoid pushing these plugs beneath the surrounding chondral surface (Fig 10B). Once all the holes are filled and the plugs seated, the knee is put through a range of motion. The postoperative management is similar to the open procedure. If the Mosaicplasty is performed in conjunction with ligament reconstruction or meniscal repair, it is recomHANGODY ET AL

TABLE 2. Mosaicplasties of the Talus Patient

Age

Sex

1 2 3 4 5 6 7 8 9 10 11 12 13

19 16 20 26 14 32 43 28 19 18 26 24 34-

M M M F F M F F F M M F M

Diagnosis Site TOCD-MTD TOCD-MTD TOCD-MTD UOCD-LTD UOCD-LTD TOCD-LTD UOCD-MTD TOCD-LTD UOCD-MTD TOCD-LTD TOCD-MTD TOCD-MTD UOCD-MTD

Number of MP

Postoperative Laboratory

Follow Up

Bandi Score

Hanover Score

3 2 3 2 4 4 2 2 3 4 2 4 3

X, MRI, CT X, 3D-CT, MRI X, MRI, CTA X, MRI, CA X, 3D-CT X, CTA X, 3D-CT X, MRI, CTA X, MRI, CA X, 3D-CT X, MRI, CT X, MRI, CT X, 3D-CT

24 12 12 15 14 16 19 21 24 24 25 26 28

0 0 0 0 3 0 0 0 0 1 0 0 3

96 88 100 100 100 + 4 98 94 100 92 100 + 2 98 92 88

Abbreviations: BX, biopsy; CA, control arthroscopy; CTA, computed tomographic arthrography; LTD, lateral taiar done; MRI, magnetic resonance imaging; MTD, medial taiar done; 3D-CT, three-dimensional computed tomography; TOCD, traumatic osteochondritis dissecans; UOCD, undetermined cause steochondritis dissecans; US, ultrasound; X, radiograph.

mended that osteochondral grafting be done first. If performed in the reverse order, flexion of the knee may be compromised, making a posterior defect inaccessible. RESULTS The results to date are taken from the 168 patients operated on in Budapest, Hungary, and Portsmouth, New Hampshire, from April 1992 through January of 1996. One of the authors (GK) has had the opportunity to evaluate each group in follow-up. The longest follow-up in Hungary has been 5 years and that in the United States, 18 months. Of these patients, the combined results have been good to excellent, using a modified Hospital for Special Surgery Score (HSS) knee score for the femoral condylar lesions, Bandi score for the donor site and patellar lesions, and the Hanover scoring system for the talus. 17-19 As experience has been gained, more cases have been done arthroscopically, with 44 case results having recently been reported. 2°

The clinical results of these cases parallel the results of the original study group (Table 1). The mean age was 32.4 (range 17-45), an average of 8 grafts (1-18) in the knee and 2 (1-4) in the ankle were used. One hundred and twenty-nine osteochondral mosaicplasties have been done on the femoral condyles (48 for OCD, 81 for Grade III to IV traumatic chondral defects), 26 of the patella (15 traumatic chondromalacia, 9 idiopathic, and 2 OCD). Thirteen mosaicplasties of the talus have been performed (Table 2). There have been no infections or thrombophlebitis. There is no evidence of graft loosening, protuberance, or subsidence. There have been three painful postoperative hematomas that were relieved by aspiration, and the subsequent postoperative courses were uneventful. In the early Portsmouth experience, one case of OCD of the lateral femoral condyle failed when attempt was made to reattach the fragment with a single osteochondral plug. The fragment did not unite and sheared off. A subsequent 7

Fig 11. Case of lateral femoral condyle OCD. (A) Preoperative radiograph of lateral OCD. (B) Intraoperative 7 plug Mosaicplasty. (C) Radiograph at 6 months postoperative of 7 plug Mosaicplasty for treatment of OCD.

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31 9

loss of grafted cartilage was observed in any of the control arthroscopies. Histological evaluation of the biopsies revealed fibrocartilage tissue at the donor sites and survival of the transplanted cartilage. The recipient site biopsies were examined with standard stains, by light and polarized microscop)~ and by enzymal chemical techniques. 2~Histologically, the transplanted cartilage retained its hyaline characteristics (type II collagen, glycosaminoglycan [GAG], and so on) and showed deep matrix integration as the grafts matured (Fig 13). The Portsmouth group has been followed-up for one year. This follow-up interval is too short to draw any conclusions other than to note that these patients are following the same clinical course as their counterparts in Hungary.

DISCUSSION Fig 12. Follow-up arthroscopy of arthroscopic Mosaicplasty of four 4.5 mm plugs at 12 weeks. The probe is resting on plug.

plug Mosaicplasty was then performed. Six months after surgery the patient has full range of motion, no pain, and radiographs show consolidation of the graft (Fig 11). The Budapest group has been evaluated at set interval clinical examinations (2 weeks, 4 weeks, 6 weeks, 8 weeks, 3 months, 6 months, 1 year, 1.5 years, 2 years, and then yearly). Radiographs have been done on all, computed tomographic (CT) arthrograms on 16 (13 knees, 3 ankles), and MRI on 69 (62 knees, 7 ankles). Control arthroscopies were performed in 33 (31 knees and 2 ankles), and biopsies obtained in 20 (19 knees and i ankle) of those cases. By 3 months, all the patients were full-weight-bearing without complaints or loss of knee motion or function. In those patients followed up for more than one year, return to normal activities, including competitive sports and work, has been the rule. Because of the nature of the lesions, the patellar cases and femoral condylar lesions requiring more than four plugs have taken longer to make a full clinical recovery. The average modified HSS score value for the femoral group is 82.5 (65-100). The Bandi score demonstrated patellar complaints in five cases. There were three mild and two severe functional complaints among the patella implant group. The average Hanover score for the talus was 92 (range, 82-100 out of a possible 100). The patients who have been followed-up for 2 years and longer (83 femoral condyles, 17 patellas, 5 tali) continue to do well and maintain their one year scores. Radiographs were performed on all patients. No loss of joint space or degenerative changes have been noted to date. The 16 CT arthrograms showed congruent surfaces and no dye leakage into the grafts. Control arthroscopies were indicated when: (1) a second injury occurred (9 cases); (2) a second surgery was necessary (6 ACL, 8 high tibial osteotomy [HTO]); and (3) the earliest time of safe return to professional sports (10 cases) needed to be determined. These arthroscopies demonstrated fibrocartilage-like tissue filling the donor sites and between the transplanted grafts. They appeared hyaline-like in color and consistency, and the surfaces remained congruent (Fig 12). No 320

Autogenous small cylindrical osteochondral grafts have been used to treat severe localized articular cartilage defects on the weight-bearing areas of the knee and ankle since 1992. The open procedure uses techniques familiar to the orthopaedic surgeon; it is independent of laboratory or tissue bank support and is cost effective because it is a one-stage procedure performed with reusable equipment. The ankle procedure does require the entrance of two joints (the knee remains the best source of the grafts), but, to date, no long-term knee morbidity has been encountered. Newly designed commercially available arthroscopic instruments make the technically demanding arthroscopic procedure more predictable. Perpendicular insertion of small grafts remains the most important aspect of good recipient site congruity. Although the arthroscopic method potentially can reduce short-term morbidity and shorten the rehabilitation, if perpendicular graft placement cannot be. easily achieved, the surgeon and patient should be prepared for an open procedure. In the study group of patients, the articular surface of the supracondylar ridge of the distal femur has proven to be a safe area from which small cylindrical osteochondral grafts can be taken. Other areas of the femur have been used: the periphery of the femur below the entrance to the intercondylar notch (A. Miniacci, personal communication, February 1997), and the ridge at the entrance to the notch, s Both areas are reserved for secondary use when many grafts are needed. Only cylinders of 2.7 m m or less are taken from the distal periphery. The intercondylar area, though easily accessible, is highly contoured and, according to others, is a mixture of fibro and hyaline cartilage. 22 Other authors have used the lateral patella for autogenous grafting without significant patello-femoral joint morbidity. ~s A major concern at this stage in the study is whether the procedure will prevent or delay the development of arthritis in the years to come. Shapiro et al postulated that the deep matrix integration of the repair cartilage and the recipient cartilage is needed to resist vertical shear stresses and prevent micromotion that leads to degenerative changes. 24 Brittberg et al and others have also made this point and consider the sealing of the cartilage to be a key element for symptom relief. 25,26 At the recent Articular Cartilage Regeneration Symposium, Professor Mow conHANGODY ET AL

Fig 13. Histological analysis of biopsy specimens obtained from the femoral chondylar recipient sites 4 to 5 years after Mosaicplasty for the treatment of focal chondral defects (FCD) and OCD. (A) View at 4 years postoperative of 6 FCD plugs: transplanted cartilage with normal appearing chondrocytes and mucopolysaccharide content (sour mucopolysaccharide alcian blue; original magnification x120). (B) View at 4.5 years postoperative of 8 0 C D plugs: transplanted cartilage maintaining high glycosaminoglycan (GAG) content (GAG specific n'n' dietil pseudoisocyanide at pH 7; original magnification x50). (C) View of same specimen and stain seen in (B) at 4.5 years postoperative under polar light showing hyaline cartilage orientation of the chondrocytes and matrix elements (original magnification x50). (D) View at 5 years postoperative FCD: junction of the donor hyaline cartilage (left) and the in-growth fibrocartilage (right). The transplanted cartilage has retained its GAG staining intensity and no gaps are seen between the two tissues (toluidine blue; original magnification x20). (E) View at 5 years postoperative FCD of same case as (D). Under hematoxylin-eosin staining, again there appears to be matrix integration between the hyaline cartilage and the fibrocartilage (original magnification x20).

cluded, "If we do not have strong knitting at the juncture, that tissue is doomed by physical principles to fail. It may be three years, it may be five years, but I can predict it as simply as Newton's laws. ''27 To date, our clinical histological evaluations have been limited to 19 specimens (femoral condyle from 12 weeks to 5 years) and animal specimens up to 1 year. These specimens were taken at the junction of the recipient surface, donor plug, and intervening fibrocartilage grouting. They were subjected to light, polar, and electron microscopic evaluation, as well as image analysis. On all sections, the specimens showed evidence of bonding of the three cartiMOSAICPLASTY

lage matrices at the interfaces. Although convincing, these are limited studies. Animal studies continue to be conducted to add more evidence of the matrix integration in the Mosaicplasty procedure. These observations and the continued relief Of symptoms in the patients followed up for 5 years have been encouraging. A preliminary report of the prospective study in Portsmouth is in preparation. The Mosaicplasty is offered as a safe, effective, and reproducible alternative for the treatment of focal chondral defects and OCD of the femoral condyles, patella, and talus. 321

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