Rush University Medical Center, Chicago, Illinois, USA.
Am J Sports Med. 2021 May;49(6):1505-1511. doi: 10.1177/03635465211003074. Epub 2021 Apr 8.
Osteochondral allograft transplantation is 1 treatment option for focal articular cartilage defects of the knee. Large irregular defects, which can be treated using an oblong allograft or multiple overlapping allografts, increase the procedure's technical complexity and may provide suboptimal cartilage and subchondral surface matching between donor grafts and recipient sites.
To quantify and compare cartilage and subchondral surface topography mismatch and cartilage step-off for oblong and overlapping allografts using a 3-dimensional simulation model.
Controlled laboratory study.
Human cadaveric medial femoral hemicondyles (n = 12) underwent computed tomography and were segmented into cartilage and bone components using 3-dimensional reconstruction and modeling software. Segments were then exported into point-cloud models. Modeled defect sizes of 17 × 30 mm were created on each recipient hemicondyle. There were 2 types of donor allografts from each condyle utilized: overlapping and oblong. Grafts were virtually harvested and implanted to optimally align with the defect to provide minimal cartilage surface topography mismatch. Least mean squares distances were used to measure cartilage and subchondral surface topography mismatch and cartilage step-off.
Cartilage and subchondral topography mismatch for the overlapping allograft group was 0.27 ± 0.02 mm and 0.80 ± 0.19 mm, respectively. In comparison, the oblong allograft group had significantly increased cartilage (0.62 ± 0.43 mm; < .001) and subchondral (1.49 ± 1.10 mm; < .001) mismatch. Cartilage step-off was also found to be significantly increased in the oblong group compared with the overlapping group ( < .001). In addition, overlapping allografts more reliably provided a significantly higher percentage of clinically acceptable (0.5- and 1-mm thresholds) cartilage surface topography matching (overlapping: 100% for both 0.5 and 1 mm; oblong: 90% for 1 mm and 56% for 0.5 mm; < .001) and cartilage step-off (overlapping: 100% for both 0.5 and 1 mm; oblong: 86% for 1 mm and 12% for 0.5 mm; < .001).
This computer simulation study demonstrated improved topography matching and decreased cartilage step-off with overlapping osteochondral allografts compared with oblong osteochondral allografts when using grafts from donors that were not matched to the recipient condyle by size or radius of curvature. These findings suggest that overlapping allografts may be superior in treating large, irregular osteochondral defects involving the femoral condyles with regard to technique.
This study suggests that overlapping allografts may provide superior articular cartilage surface topography matching compared with oblong allografts and do so in a more reliable fashion. Surgeons may consider overlapping allografts over oblong allografts because of the increased ease of topography matching during placement.
同种异体骨软骨移植是治疗膝关节局灶性关节软骨缺损的 1 种治疗选择。较大的不规则缺损可采用长形同种异体移植物或多个重叠的同种异体移植物进行治疗，这增加了手术的技术复杂性，并且可能导致供体移植物与受区之间的软骨和软骨下表面匹配不佳。
使用三维模拟模型量化和比较长形和重叠同种异体移植物的软骨和软骨下表面形貌不匹配以及软骨台阶。
对照实验室研究。
对 12 个人体股骨内侧髁的尸体进行计算机断层扫描，并使用三维重建和建模软件将其分割为软骨和骨成分。然后将这些片段导出到点云模型中。在每个受区髁上创建 17×30mm 的模型缺损大小。每个髁的供体同种异体移植物有 2 种类型：重叠和长形。虚拟采集移植物并进行移植，以与缺损最佳对齐，从而使软骨表面形貌不匹配最小化。使用最小均方距离来测量软骨和软骨下表面形貌不匹配以及软骨台阶。
重叠同种异体移植物组的软骨和软骨下表面形貌不匹配分别为 0.27±0.02mm 和 0.80±0.19mm。相比之下，长形同种异体移植物组的软骨（0.62±0.43mm； <.001）和软骨下（1.49±1.10mm； <.001）不匹配显著增加。与重叠组相比，长形组的软骨台阶也明显增加（ <.001）。此外，与重叠组相比，重叠同种异体移植物更可靠地提供了更高比例的临床可接受的（0.5 和 1mm 阈值）软骨表面形貌匹配（重叠：0.5 和 1mm 均为 100%；长形：1mm 为 90%，0.5mm 为 56%； <.001）和软骨台阶（重叠：0.5 和 1mm 均为 100%；长形：1mm 为 86%，0.5mm 为 12%； <.001）。
这项计算机模拟研究表明，与长形同种异体骨软骨移植物相比，使用与受区不匹配的供体移植物时，重叠同种异体骨软骨移植物在治疗股骨髁的大而不规则的骨软骨缺损方面具有更好的形貌匹配和降低的软骨台阶。这些发现表明，在处理涉及股骨髁的大而不规则的骨软骨缺损时，重叠同种异体移植物可能在技术上优于长形同种异体移植物。
这项研究表明，与长形同种异体移植物相比，重叠同种异体移植物可能提供更好的关节软骨表面形貌匹配，而且其匹配更可靠。由于在放置过程中更易于进行形貌匹配，外科医生可能会考虑重叠同种异体移植物而非长形同种异体移植物。
