Chondral Delamination of Fresh Osteochondral Allografts after Implantation in the Knee: A Matched Cohort Analysis

Abstract

Introduction Delamination of the chondral surface of an osteochondral allograft (OCA) from the underlying cancellous bone has been described as a mode of failure after implantation in the knee. Our hypothesis was that increased storage time of the OCA is associated with increased risk of graft delamination after implantation. Methods Prospective data on 13 patients with evidence of OCA delamination identified on magnetic resonance imaging or during subsequent surgery from 2000 to 2015 were reviewed. A cohort of 33 patients without evidence of graft delamination were then matched to the delamination group based on recipient age, sex, body mass index (BMI), and chondral defect location. The matched cohort size was established based on a power calculation for determining differences in OCA storage times. All patients had a minimum 2-year follow-up. Results There was no difference in donor age, donor sex, and graft storage time between groups (30 vs. 31 days, P = 0.78). There were no differences between number of previous ipsilateral knee surgeries (1.8 vs. 0.84, P = 0.26), BMI (26.8 vs. 25.0 kg/m, P = 0.31), total chondral defect size (6.5 vs. 5.8 cm, P = 0.41) or preoperative Marx activity scores between groups. Conclusion There is no association between OCA storage time, activity level scores, or number of previous ipsilateral knee surgeries and graft delamination in our patient population. Further work is needed to identify the etiology for this mode of failure of OCAs.

Shorter Storage Time Is Strongly Associated With Improved Graft Survivorship at 5 Years After Osteochondral Allograft Transplantation

“…These rates of graft survival and their inverse correlation with graft storage time are in accordance with the findings of previous preclinical and clinical studies. 22,25,[27][28][29][30]32 Taken with the findings of numerous other investigations, our study adds strong evidence to support the successful survivorship of OCAs in the treatment of osteochondral defects of the knee. The improved survivorship of early transplantation grafts at .90% was evident at the 2-year postoperative time point and persisted out to 5 years, whereas the survivorship of late transplantation grafts continued to decline (Figure 1).…”

“…Data recently published by Schmidt et al 30 and Rauck et al 29 refute the correlation of increased OCA storage time with clinical outcomes and graft delamination, respectively. Schmidt et al performed a matched-pair cohort study of 75 patients who received early release OCAs (mean storage, 6.3 days) between 1997 and 2002.…”

“…Rauck et al 29 examined cohorts of patients with and without evidence of OCA delamination who were matched by recipient age, sex, body mass index, and chondral defect location. Their cohort size was based on a power calculation needed to detect a difference in storage time ≥4 days between groups (power, 0.80; significant level of alpha, .05).…”

“…Conversely, Schmidt et al 30 demonstrated no difference in postoperative clinical outcomes in a matched-pair analysis of patients who received early release grafts (mean storage, 6.3 days) versus patients who underwent OCA transplantation with late-release grafts (mean storage, 20.0 days). In another matched-control study, Rauck et al 29 found no association between OCA storage time and rates of postoperative graft delamination, with an average storage time of 30 days in the delamination group and 31 days in the intact control group.…”

Osteochondral Allograft Transplantation in Professional Athletes: Rehabilitation and Return to Play

“…If the allograft bone does not integrate into the host bone, in vivo graft subsidence or delamination of the articular cartilage surface can occur as the graft sees higher loads. 21 At the same time, it is known that moderate mechanical loading is healthy for articular cartilage of the knee as it promotes interstitial fluid flow in and out of the permeable collagen-proteoglycan matrix, facilitating the movement of nutrients from the synovial fluid into the collagen matrix and stimulating an anabolic chondrocyte reponse. 7,[9][10][11] At this time, there is a lack of consensus on the optimal post-operative weight bearing regimen after OCA, which is likely dependent on multiple factors, including the biochemical and mechanical properties of the transplanted graft at time zero and evolution of these properties during the early post-operative healing period, as well as the technical aspects of the transplant surgery (quality of press-fit fixation, topography of graft compared to host surface, etc).…”