Fresh Stored Allografts for the Treatment of Osteochondral Defects of the Knee

Background: Osteochondral allograft reconstruction of articular cartilage defects is a well-established cartilage repair strategy. Currently, fresh osteochondral allograft tissue is commercially available to clinicians approximately thirty days following graft harvest. Little clinical information is available on the outcome of patients who have been treated with fresh allografts stored for several weeks or more. The purpose of this study was to prospectively analyze the clinical outcome and graft morphology of patients who received fresh, hypothermically stored, allograft tissue for the treatment of symptomatic chondral and osteochondral defects of the knee.

Methods: Nineteen patients with symptomatic chondral and osteochondral lesions of the knee who were treated with fresh osteochondral allografts between 1999 and 2002 were prospectively followed. The mean age at the time of surgery was thirty-four years. Validated outcomes instruments (the Activities of Daily Living Scale and the Short Form-36) were used; all patients must have had a baseline functional score prior to surgery and a minimum two-year follow-up evaluation. All grafts were obtained from commercial vendors; the mean preimplantation storage time of the graft was thirty days (range, seventeen to forty-two days). The mean lesion size was 602 mm2. Magnetic resonance imaging was used to evaluate the morphologic characteristics of the implanted grafts.

Results: The mean duration of clinical follow-up was forty-eight months (range, twenty-one to sixty-eight months). The mean score (and standard deviation) on the Activities of Daily Living Scale increased from a baseline of 56 ± 24 to 70 ± 22 at the time of the final follow-up (p < 0.05). The mean Short Form-36 score increased from a baseline of 51 ± 23 to 66 ± 24 at the time of final follow-up (p < 0.005). With the numbers studied, we could not correlate graft storage time, body mass index, lesion size, lesion location, or patient age with the functional outcome scores. At a mean follow-up interval of twenty-five months, cartilage-sensitive magnetic resonance imaging demonstrated that the normal articular cartilage thickness was preserved in eighteen implanted grafts, and allograft cartilage signal properties were isointense relative to normal articular cartilage in eight of the eighteen grafts. Osseous trabecular incorporation of the allograft was complete or partial in fourteen patients and poor in four patients. Complete or partial trabecular incorporation positively correlated with Short Form-36 scores at the time of follow-up (r = 0.487, p < 0.05).

Conclusions: Fresh osteochondral allografts that were hypothermically stored between seventeen and forty-two days were effective in the short term both structurally and functionally in reconstructing symptomatic chondral and osteochondral lesions of the knee.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.