Anterior cruciate ligament (ACL) tears increase early onset osteoarthritis (OA) risk leading to cartilage and bone degradation. While the contribution of bone in OA development is unclear, evidence suggests that bone changes accompany cartilage degradation. This study aims to assess if regions with differences in subchondral bone plate thickness have differences in cartilage thickness when comparing ACL reconstructed (ACLR) knees of women ≥5 years post-injury to contralateral and controls with uninjured knees.
Magnetic resonance imaging (MRI) assessed cartilage and high resolution peripheral quantitative computed tomography (HR-pQCT) assessed subchondral bone in both knees. Multimodal 3D image registration aligned anatomy. Maps of the spatial distribution of thickness on the articular surfaces were generated to compare women with ACL reconstructions to contralateral and controls with uninjured knees.
ACLR knees had a thicker subchondral bone plate in the posterior and central lateral femur compared to contralateral knees (10.4% and 4.2% thicker, P = 0.032 and 0.032, W = 108 and 107, respectively) and in the posterior lateral femur compared to control knees (17.1% thicker, P = 0.014, W = 177). Cartilage differences were not detected (P > 0.05) in these regions.
This study demonstrates that subchondral bone plate thickness differences are prominent following knee injury, as measured by HR-pQCT, but no statistically significant differences in cartilage morphology, measured by MRI, were found between ACLR knees compared to contralateral and control knees. These data provide novel insight into post-traumatic knee injuries that may be signs of early OA pathogenesis.