Osteochondral Defects and Patellar Autografts
abstract & commentary
Synopsis: Osteochondral defects in the knee have many avenues of treatment. This long-term study documents good functional results with a unique source of osteochondral tissue, the lateral patellar facet.
Source: Outerbridge HK, et al. Osteochondral defects in the knee. A treatment using lateral patella autografts. Clin Orthop Rel Res 2000;377:145-151.
Although an explosion of osteochondral procedures to treat defects of the knee have occurred over the past 10 years, none have solved the problem of isolated articular defects with respect to long-term follow-up, complete restoration of the hyaline surface, and harvest site morbidity. Treatment options currently include drilling or microfracture techniques, allograft transplantation, autograft transplant (mosaicplasty vs en bloc transfer), and genetic engineering techniques using tissue harvest, chondrocyte replication, and eventual reimplantation under a perisosteal covering (Carticel, Genzyme, Boston, Mass.).1,2 Most clinical applications of these treatments are for weightbearing surfaces of the distal femur.
Outerbridge and colleagues, in this long-term follow-up study, discuss their results with en bloc transfer of the lateral patellar facet to either the medial or lateral femoral condylar weightbearing surface. The procedure, which was first performed in 1982 and described in 1995, uses an open approach with harvest of the lateral patellar facet for implantation to the prepared, rectangular, articular defect with press-fit fixation. Postoperatively, continuous passive motion was used from four to seven days. Full weightbearing was begun at six weeks. Outerbridge et al followed 18 knees in 16 patients (13 male, 3 female) retrospectively for a minimum of two years (range, 2-14.6 years; average follow-up, 7.6 years). Average age of the patients was 27 years (range, 17-50 years). Defect sizes averaged 453 mm2 (range, 150-1080 mm2). Follow-up data focused on the Cincinnati Knee score with an average preop score of 37 and postoperative score of 83 (range, 19-100).
Outerbridge et al noted mild to moderate complications with the following: 1) five patients with a fixed flexion contracture of 2-5°; 2) 5 patients requiring repeat arthroscopy, but only one with a small area of articular delamination; and 3) two of 18 knees with moderate symptoms related to the patellofemoral joint. Outerbridge et al noted that 81% (13 of 16 patients) returned to a high level of functioning.
Comment By Robert C. Schenck, Jr., MD
This retrospective review is useful for the practicing sports medicine specialist as it clearly describes an ingenious technique for the autografting of femoral articular weightbearing defects. Most surgeons, however, when reading the description wince at the suggestion of the harvest of the lateral facet of the patella. Although Outerbridge et al noted only two patients with patellofemoral symptoms, this corresponds to an 11% complication rate and, although acceptable, carries some concern. Furthermore, the risk of a fixed flexion deformity (31% of patients) is the worry of any sports physician as it can outweigh the benefits of the treatment. Use of aggressive-passive extension exercises are essential in the use of this procedure. Surprisingly, in their discussion, Outerbridge et al compared their technique to that of allograft procedures. There are several published reports on mosaicplasty and a comparison to the autografting would have made for an interesting comparison of two similar but distinctly different techniques.3,4
Despite the advent of techniques and instrumentation for mosaicplasty procedures, both it and the use of the lateral facet of the patella are plagued by the worry of donor site morbidity. The application of mosaicplasty appears to have a more accepted application on this side of the Atlantic; however, the technique by Outerbridge et al is compelling and may be a consideration for large isolated defects such as with a large chondral lesion secondary to osteochondritis dissecans.5
References
1. Mandelbaum BR, et al. Articular cartilage lesions of the knee. Am J Sports Med 1998;26:853-861.
2. Peterson L, et al. Two-to-nine year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop Rel Res 2000;374:212-234.
3. Bobic V. Arthroscopic osteochondral autograft in anterior cruciate ligament reconstruction: A preliminary clinical study. Arthroscopy 1996;3:262-264.
4. Hangody L. Autogenous osteochondral graft technique for replacing knee cartilage defects in dogs. Orthopedics Int 1997;5:175-181.
5. Schenck RC Jr., Goodnight JM. Current concepts review: Osteocondritis dissecans. J Bone Joint Surg 1996;78:439-455.
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