AANA Lab Course 1002 -3rd Annual Fellows/Chief Residents-Large Chondral Allograft-Nicholas Early, M.D.

Large Chondral Allograft-Nicholas Early, M.D.

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This presentation by Dr. Nicholas A. Early addresses the management of large chondral defects in the knee, focusing on diagnosis, workup, and treatment options including osteochondral allograft (OCA) and autologous chondrocyte implantation (ACI).<br /><br />Chondral and osteochondral defects cause significant morbidity and require complex treatment algorithms. Both OCA and ACI have demonstrated successful outcomes for large lesions (>2 cm²). ACI tends to yield better results if performed as the initial intervention without prior marrow stimulation (e.g., microfracture). OCA results have improved notably, with systematic reviews showing 75-82% of athletes return to sport following OCA, challenging its reputation as only a last-resort option.<br /><br />Diagnosis involves detailed history taking, focused physical examination for localized pain, mechanical symptoms, and effusions, and imaging including weight-bearing and full-length x-rays, as well as MRI for cartilage defect assessment. Patient factors such as BMI, smoking status, limb alignment, and inflammatory conditions also influence outcomes.<br /><br />Osteochondral allografts are suitable for chondral/osteochondral lesions, osteochondritis dissecans, and necrotic bone, often performed in a single stage. Surgical technique emphasizes correct positioning, matching graft curvature and depth, careful approach to avoid meniscal damage, minimizing immunogenicity via pulse lavage, and secure press-fit fixation without cartilage crushing. "Snowman" technique allows overlapping grafts for larger defects.<br /><br />Autologous chondrocyte implantation, particularly third-generation matrix-assisted methods, is effective for large or irregular lesions with up to 6 mm bone loss. It involves harvesting cartilage, preparing a defect with vertical borders, applying chondrocytes seeded onto a collagen membrane, securing with fibrin glue, and meticulous hemostasis. Rehabilitation protocols emphasize continuous passive motion (CPM) and progressive range of motion and weight bearing, with proper expectation management.<br /><br />In summary, managing large chondral knee defects requires precise diagnosis, patient-specific considerations, and selection between advanced OCA and ACI techniques to optimize functional outcomes and return to activity.

Keywords

large chondral defects

knee cartilage injury

osteochondral allograft (OCA)

autologous chondrocyte implantation (ACI)

diagnosis of cartilage lesions

microfracture contraindications

return to sport after OCA

imaging for cartilage defects

surgical techniques for cartilage repair

rehabilitation after cartilage surgery