A modified parapatellar approach for the creation of osteochondral defects in sheep.

Abstract

Osteoarthritis is a problem of great social and economic importance in elderly populations, mostly in developed countries. Current treatments aim to relief the clinical signs and slow the disease development, rather than cure it. Beyond this point, cartilage regeneration has recently received much attention from bioengineering industry, mostly because it’s acknowledged that early treatments of osteochondral defects (OCD) are crucial for slowing or even preventing the chronic development of OA. The sheep is considered a promising large animal model for the testing of bone implant materials because of its potential to support preclinical translation. Several surgical techniques for the creation of the osteochondral defects have already been described. However, some use the classical medial parapatellar approach to the medial condyle of the femur, which is considered unsafe due to its high risk of posterior patellar luxation and the development of secondary osteoarthritis. This will potentially interfere with the biological and biomechanical response of the osteochondral unit to biomaterials. The aim of this study was to develop a modified medial parapatellar approach to the creation of osteochondral defects in sheep to further test novel biomaterials and scaffolds, with the goal of favouring early weight bearing. In order to do so, all sheep underwent medial arthrotomy to access the left femoral condyle. The limb was flexed to allow access to the centre of the medial condyle and drilling of the defect without the disruption of the oblique medial vastus muscle, thus reducing postsurgical morbidities. Early loadbearing was observed in all animals and kept through the implantation period.