What Implications Does ACL Reconstruction Have on the Future Development of Degenerative Arthritis?
The causes of degenerative joint disease in the post-traumatic knee are multifactorial and include the following: articular impaction with initial trauma, meniscal injury, operative trauma, and abnormal knee kinematics.
Articular impaction of the lateral femoral condyle by the posterolateral tibial plateau may occur at the time of anterior cruciate ligament (ACL) rupture when the tibia subluxes anteriorly with some internal rotation. The archetypal bone bruising pattern associated with this impaction is best visualized on the sagittal images of the knee as increased T2 signal in the region of the sulcus terminalis of the lateral femoral condyle and the posterolateral tibial plateau. A recent review of the literature on the natural history of these bone bruises concluded that this blunt injury to the articular cartilage and subchondral bone can alter articular cartilage homeostasis and induce early degenerative changes.1
Injury to the meniscus (Figure 49-1) occurs in approximately 25% of ACL ruptures. A literature review that examined the frequency of post-traumatic knee degenerative joint disease found a number of retrospective studies with follow-up times between 5 and 20 years.2 These authors concluded that 50% to 70% of patients with an ACL rupture combined with meniscus tear have some radiographic changes after 15 to 20 years.2 Further, one study of 53 patients at 7 years post–ACL reconstruction found that acute ACL reconstruction with meniscal preservation was shown to have the lowest incidence of radiographic evidence of degenerative changes.3
Figure 49-1. A bucket-handle meniscal tear is often associated with ACL rupture, as in this case.
The goal of ACL reconstruction is to restore stability in order to prevent future subluxation events, preserve the meniscus, and minimize further degenerative changes. However, the operative trauma of ACL reconstruction may contribute to the development of degenerative joint disease. The procedure commonly results in a hemarthrosis. Rare postoperative complications of knee sepsis and arthrofibrosis probably increase the risk for knee arthritis as well. Further, the tunnels required for graft passage (Figure 49-2) subtly alter the bony architecture that supports the joint surfaces.
Figure 49-2. Standard tunnels required for graft passage are approximately 10 mm in diameter initially and may dilate further with time. These tunnels may alter the bony architecture that supports the joint surfaces similar to a mattress with an inadequate foundation (box spring).
Tearing or rupturing your ACL alters the normal mechanics (kinematics) of the knee. Even the most successful ACL reconstructions do not restore normal knee kinematics. Abnormal knee kinematics accelerate the normal wear of the articular surfaces.
The exact contribution of each injury, patient characteristics, and activity demands on the knee are not known but are being investigated by multicenter prospective longitudinal studies.
1. Nakamae A, Bahr R, Krosshaug T. Natural history of bone bruises after acute knee injury: clinical outcome and histopathological findings. Knee Surg Sports Traumatol Arthrosc. 2006;14:1252-1258.
2. Gillquist J, Messner K. Anterior cruciate ligament reconstruction and the long term incidence of gonarthrosis. Sports Med. 1999;27:143-156.
3. Jomha NM, Borton DC, Clingeleffer AJ, Pinczewski LA. Long term osteoarthritic changes in anterior cruciate ligament reconstructed knees. Clin Orthop Relat Res. 1999;358:188-193.