Osteochondral allograft transplantations (OCAs) are becoming a mainstay of treatment for knee-cartilage injuries. To help ensure that the allograft plug is transplanted with <1 mm of step-off from the surrounding recipient cartilage, many surgeons restrict themselves to orthotopic OCAs—matching the graft-recipient condyles in a lateral-to-lateral or medial-to-medial fashion.
However, in the October 4, 2017 issue of The Journal of Bone & Joint Surgery, Wang et al. demonstrated that both orthotopic and non-orthotopic (e.g., lateral condyle-to-medial condyle) OCA resulted in significantly improved outcomes in 77 cases followed for a mean of 4.3 years. The authors found that reoperation rates and pre- and postoperative scores in physical functioning and pain did not differ significantly between the orthotopic (n=50) and non-orthotopic (n=27) groups. These results suggest that condyle-specific matching may not be necessary.
One problem with orthotopic OCA is that 75% of the available allograft is supplied in the form of lateral condyles, while most full-thickness cartilage lesions presenting for treatment occur in the medial condyle. Consequently, surgeon preferences for orthotopic OCA limit the number of available matches and lead to an estimated 13% of available grafts being discarded.
Noting that many factors contribute to successful resurfacing of cartilage defects in the knee, the authors say that “it may be overly simplistic to assume that a conventionally matched orthotopic allograft will ensure a smooth surface contour at the recipient site.” They go on to conclude that “if surgeons forewent condyle-specific matching, more allografts would be readily available, which would shorten wait times, provide fresher grafts with increased chondrocyte viability, and lower procedure costs.”