Interactions Between Graft Placement, Gait Mechanics, and Premature Osteoarthritis Following Anterior Cruciate Ligament Reconstruction

The interaction between anterior cruciate ligament (ACL) graft placement and changes in walking mechanics is examined in the context of the maintenance of cartilage health and conditions leading to premature osteoarthritis in the ACL-reconstructed knee. Based on reports that healthy cartilage is regionally conditioned over time to the repetitive patterns of loading specific to walking, this paper explores the potential that cartilage degeneration can be initiated when a condition such as ACL injury changes the ambulatory joint mechanics in a manner that shifts loads to unconditioned regions of cartilage. Thus, restoring the anatomical placement and function of the ACL is an important consideration in re-establishing the balance between ambulatory loading and biological maintenance of articular cartilage to prevent the premature initiation of osteoarthritis. The current findings indicate that standard ACL reconstruction techniques often fail to replicate the anatomical placement of the native ACL, restore normal ambulatory mechanics, or prevent early onset osteoarthritis. The combination of information from three-dimensional models of ACL graft orientation derived from magnetic resonance imaging and the analysis of knee mechanics during walking has demonstrated that alterations in knee rotation are related to nonanatomic graft orientation. This material suggests that placement of the graft in a nonanatomic orientation is one of the critical factors responsible for the negative long-term outcomes of the ACL-reconstructed knee. In conclusion, the proposed sensitivity of cartilage health to changes in ambulatory mechanics demonstrates the importance of restoring normal ACL anatomy and function to avoid premature osteoarthritis after ACL injury and motivates the need to evaluate walking mechanics when developing new treatment modalities for the ACL-injured knee.