Surgical Preparation for Articular Cartilage Regeneration in the Osteoarthritic Knee Joint.

Purpose: Autologous chondrocyte implantation (ACI) is a treatment option even in early osteoarthritis (OA). Surgical preparation for ACI should avoid penetration of the subchondral bone plate to prevent hemorrhage, fibrin clot formation, and subsequent activation of the inflammatory response.

Hypothesis: Current surgical procedures with ring curettes preserve the integrity of the subchondral bone plate, even in patients with OA.

Methods: Subchondral femoral bone plates ( n = 40) of OA knees undergoing total knee arthroplasty were prepared in vivo using standard, non-brute-force debridement for ACI. To approach regular wear/early OA, only cartilage with maximally grade 3A International Cartilage Repair Society score was prepared. Effects were analyzed by light microscopy.

Results: In 87.5% of the specimens (35/40), standard debridement did not violate the tide mark, except for occasional minor openings with a smooth edge (diameter approximately 20 µm). In contrast, 5/40 samples (12.5%) showed one large area with a missing bone plate and an open bone marrow space. Twenty-eight specimens (70%) showed at least remnants of uncalcified cartilage.

Conclusion: On the basis of size/fine structure, the occasional minor openings are likely due to increased vascular penetration through the tide mark in the pathologically altered bone-cartilage interface in OA. The consequences of limited hemorrhage through minor openings or selected large defects following in vivo debridement are still unknown. Thus, standard debridement appears suitable for cartilage regeneration even in OA defects.