Toward improved clinical relevance of cartilage insult models in the rabbit knee: surgical access to the habitual weight-bearing region.

OBJECTIVE: This article addresses considerations for using a posterior (popliteal) instead of anterior (para-patellar) approach for experimental insult to the rabbit knee medial femoral condyle (MFC) surface in vivo. The posterior approach is particularly advantageous when intending to address the pathomechanisms of OA associated with habitual cartilage loading, or the efficacy of a cartilage repair method, in a clinically relevant experimental setting.
DESIGN: Studies using anterior versus posterior approaches for such purposes in survival rabbit models of the MFC articular surface insults were systematically surveyed. The anterior-posterior span of the primary weight-bearing region of that surface was demonstrated cadaverically.
RESULTS: Of a total of 31 papers identified in 2007-2012, an anterior approach was utilized in 28 studies (> 90%). More than half (17/28) explicitly regarded the cranial half (inferior aspect) of the MFC surface as being a "weight-bearing" region. The insult site through anterior approach (identified in figures) was located in the cranial half region in all cases. Cadaverically, however, the center of habitual tibio-femoral contact locations on the MFC surface was located in the caudal half region (posterior aspect) of the MFC surface. The majority of the habitual contact region was accessible only by a posterior surgical approach.
CONCLUSION: For the above-noted purposes, use of a posterior (popliteal) approach, rather than an anterior approach, is highly recommended.