To determine whether a complete anterior cruciate ligament (ACL) tear, a frequent incidental finding on magnetic resonance imagings (MRIs) of individuals with established knee osteoarthritis (OA), increases the risk for further knee OA progression.
We examined 265 participants (43% women) with symptomatic knee OA in a 30-month, prospective, natural history study of knee OA. The more symptomatic knee was imaged using MRI at baseline, 15 and 30 months. Cartilage was scored at the medial and lateral tibiofemoral joint and at the patellofemoral joint using the Whole-Organ MRI Score (WORMS) semi-quantitative method. Complete ACL tear was determined on baseline MRI. At each visit, knee pain was assessed using a knee-specific visual analog scale and physical function was assessed using the Western Ontario and McMaster Universities (WOMAC) physical function subscale.
There were 49 participants (19%) with complete ACL tear at baseline. Adjusting for age, body mass index, gender and baseline cartilage scores, complete ACL tear increased the risk for cartilage loss at the medial tibiofemoral compartment [odds ratio (OR): 1.8, 95% confidence interval (CI): 1.1, 3.2]. However, following adjustment for the presence of medial meniscal tears, no increased risk for cartilage loss was further seen (OR: 1.1, 95% CI: 0.6, 1.8). Knee pain and physical function were similar over follow-up between those with and without a complete ACL tear.
Individuals with knee OA and incidental complete ACL tear have an increased risk for cartilage loss that appears to be mediated by concurrent meniscal pathology. The presence of a complete ACL tear did not influence the level of knee pain or physical function over short-term follow-up.