Osteoarthritis in patients with anterior cruciate ligament rupture: A review of risk factors

Abstract

The risk factors for the development of osteoarthritis (OA) in patients who have had an anterior cruciate ligament (ACL) rupture are reviewed. Although the principle arthrogenic factor is the increased anterior tibial displacement that is associated with the rupture, other direct and indirect factors contribute. Meniscal and chondral injuries can be present before, during, and develop after the index injury, making assessment of the relative importance of each difficult. Most studies concentrate on the radiological changes following ACL rupture and reconstruction. However the rate of significant symptomatic OA needing major surgical intervention is lower. This needs to be considered when advising patients on the management of their ruptured ACL. The long-term outcome in patients who are symptomatically stable following an ACL rupture is uncertain, although in a small cohort of elite athletes all had degenerative changes by 35 years and eight out of 19 (42%) had undergone total knee replacement. At 20 years follow-up the reported risk of developing osteoarthritis is lower after ACL reconstruction (14%–26% with a normal medial meniscus, 37% with meniscectomy) to untreated ruptures (60%–100%).

Introduction

Untreated ruptures of the anterior cruciate ligament (ACL) lead to progressive degenerative lesions in the tibiofemoral joint, and the progressive development of arthritis over decades [1]. Normal joints show loss of the bearing surface over time, which can be described as “wear and tear”, or degeneration. Osteoarthrosis can be considered the precursor of osteoarthritis (OA). Radiologically osteoarthrosis is narrowing of the joint line at greater than 50%. Less than 50% loss can be termed pre-arthrosis [2]. The concept of pre-arthrosis is important as one can hope to stabilise the cartilaginous lesions, and effect a cure. Osteoarthritis is then defined as joint space narrowing greater than 50% with exposed bone on both surfaces. This corresponds to the disappearance of cartilaginous matrix and exposure of the subchondral bone [3]. Radiological OA however may not correlate with a patient's symptoms. Pain and loss of function are the indications for surgery, not radiological findings. It is therefore important to distinguish between radiological evidence of OA, and symptoms severe enough to need major surgery, such as joint replacement. The radiological rate of OA following ACL rupture is considerably higher than the symptomatic rate, yet it is the latter that is the most important to the patient. This review will outline the risk factors for OA in patients who sustain an ACL rupture. It should also be realised that there are ACL-copers and non-copers [4]. The reported patient populations are principally those who have not coped.