Isolated Patellofemoral Unipolar Cartilage Lesions: When to Intervene

Abstract

The subset of anterior knee pain that is assigned to the patellofemoral (PF) compartment is multifactorial and may encompass structural chondral/osteochondral lesions, tendinitis, malalignment, maltracking, patella malpositioning, deconditioning, muscle imbalance, and overuse and can coexist with other lesions in the knee (i.e., ligament tear, meniscal injuries, cartilage lesions in other compartments). Chondral and osteochondral defects in the PF compartment are often encountered in clinical practice, on advanced imaging studies, and/or during arthroscopy both in symptomatic and asymptomatic patients. Studies have shown more than half of patients who undergo knee arthroscopy have chondral defects, 5.2% having Outerbridge grade III or IV lesions with 37.5% of these lesions being located in the patella alone [1]. In a review of 31,516 knee arthroscopies, 53,000 cartilage lesions were found in over 19,000 patients; most of the lesions are grade III defects in the patella [2]. In asymptomatic professional basketball players, two studies using magnetic resonance imaging (MRI) revealed the presence of abnormal chondral signal in 57% of all players, with 35% having high-grade patella signal and 25% with high-grade trochlea signal [3, 4]. A recent meta-analysis revealed that on MRI up to 52% of patients with knee pain or symptomatic knee osteoarthritis (OA) are diagnosed with cartilage lesions in the PF joint [5].