Contralateral Lateral Femoral Condyle Allografts Provide an Acceptable Surface Match for Simulated Classic Osteochondritis Dissecans Lesions of the Medial Femoral Condyle

Abstract

Background: Osteochondral allograft transplantation is an effective technique for repairing large lesions of the medial femoral condyle (MFC), but its use is limited by graft availability. Purpose/Hypothesis: The present study aimed to determine whether contralateral lateral femoral condyle (LFC) allografts can provide an acceptable surface match for posterolateral MFC lesions characteristic of classic osteochondritis dissecans (OCD). The hypothesis was that LFC and MFC allografts will provide similar surface contour matches in all 4 quadrants of the graft for posterolateral MFC lesions characteristic of OCD. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen recipient human MFCs were each size-matched to 1 ipsilateral medial and 1 contralateral LFC donor (N = 30 condyles). After a nano–computed tomography (nano-CT) scan of the native recipient condyle, a 20-mm circular osteochondral “defect” was created 1 cm posterior and 1 cm medial to the roof of the intercondylar notch (n = 10). A size-matched, random-order donor MFC or LFC plug was then harvested, transplanted, and scanned with nano-CT. Nano-CT scans were then reconstructed, registered to the initial scan of the recipient MFC, and processed in MATLAB to determine the height deviation ( d RMS) between the native and donor surfaces and percentage area unacceptably (>1 mm) proud (% A proud) and sunken (% A sunk). Circumferential step-off height ( h RMS) and percentage circumference unacceptably (>1 mm) proud (% C proud) and sunken (% C sunk) were measured using DragonFly software. The process was then repeated for the other allograft plug. Results: Both MFC and LFC plugs showed acceptable step-off heights in all 4 quadrants (range, 0.53-0.94 mm). Neither allograft type nor location within the defect had a significant effect on step-off height ( h RMS), surface deviation ( d RMS), % A proud, or % A sunk. In general, plugs were more unacceptably sunken than proud (MFC, 13.4% vs 2.4%; LFC, 13.2% vs 8.1%), although no significant differences in % C sunk were seen between allograft types or locations within the defect. In LFC plugs, % C proud in the lateral quadrant (28.0% ± 26.1%) was significantly greater compared with all other quadrants ( P = .0002). Conclusion: The present study demonstrates that 20-mm contralateral LFC allografts provide an acceptable surface match for posterolateral MFC lesions characteristic of OCD. Clinical Relevance: With comparable surface matching, MFC and LFC allografts can be expected to present similar stresses on the knee joint and achieve predictably positive clinical outcomes, thus improving donor availability and reducing surgical wait times for matches.

Osteochondral Allograft for Unsalvageable Osteochondritis Dissecans in the Skeletally Immature Knee

“…Specimens were size-matched for the patient to a radius of curvature within 2 mm of established condylar measurements from a knee magnetic resonance imaging (MRI) scan that was used by an allograft distributor (Joint Restoration Foundation) in conjunction with the procurement and supplying nonprofit entity (AlloSource). 42 All grafts were implanted within 27 days of procurement per standard industry and surgical best practice. All grafts were a maximum donor age of 25 years by surgeon practice protocol.…”

The Effect of Patellar Surface Morphology on Subchondral Bone Alignment When Matching Patellar Osteochondral Allografts to the Central Ridge of the Patella

“…A sample size calculation was performed using previously published medial and lateral femoral condyle osteochondral allograft chondral surface deviations. 26 A clinically relevant chondral difference of 0.75 mm between groups was used with a standard deviation of 0.5 mm and a power of 0.8 in a 2-tailed test (α < .05) to determine a sample size of 7 recipient patellae per group. To ensure the study was adequately powered, we chose a study sample size of 10 recipient patellae per group.…”

“…Scans were reconstructed at 40-mm resolution using the nano-CT software. 26 After the native patella was scanned, a 16-mm defect centered on the visually determined central ridge of the recipient patella was created to a depth of approximately 10 mm. A 20-mm diameter defect was originally planned; however, some of the recipient patellae were smaller than expected.…”

Medial femoral condyle width and osteochondritis dissecans: cause or effect and the implications for osteochondral allograft transplantation

“…When lesions continue to be symptomatic despite conservative management, surgical options become reasonable, including osteochondral allograft transplantation. 5 While use of non-orthotopic lateral femoral condyle grafts are excellent graft options for medial femoral condyle lesions 6 , including OCD lesions 7 , most surgeons request size-matched medial femoral condyle grafts for medial femoral condyle lesions. The width and size of the medial femoral condyle has been studied previously and there are gender and race variations.…”