Classifications in Brief: Outerbridge Classification of Chondral Lesions

Although cartilage lesions had been directly examined and described as far back as the early 20th century, the etiology of chondromalacia of the patella was not well understood when Outerbridge published his first paper on the subject in 1961 [15]. In this initial study, he evaluated the cartilage of the patella during 196 medial meniscectomies to better understand how chondromalacia progressed and which areas of the patella were primarily affected. He found that chondromalacia was most common on the medial facet as a result of constant friction with a rim on the upper border of the medial femoral condyle. He also noted the incidence of chondromalacia of the patella to be approximately 50% in patients who underwent open medial meniscectomy, even in the absence of symptoms. To better understand the etiology of chondromalacia of the patella, Outerbridge developed his classification system describing varying severity of cartilage lesions by direct visualization, which he continued to use in his subsequent papers [15-17]. Since the introduction of Outerbridge's classification system originally designed for chondromalacia of the patella, it has been adapted to include the entire knee in 1989 and other joints since then [2, 8, 13]. © 2018 by the Association of Bone and Joint Surgeons.