Slower Walking Speed Is Related to Early Femoral Trochlear Cartilage Degradation After ACL Reconstruction

Post-traumatic patellofemoral osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR) and early cartilage degradation may be especially common in the femoral trochlear cartilage. Determining the presence of and factors associated with early femoral trochlear cartilage degradation, a precursor to OA, is a critical preliminary step in identifying those at risk for patellofemoral OA development and designing interventions to combat the disease. Early cartilage degradation can be detected using quantitative magnetic resonance imaging measures, such as tissue T-2 relaxation time. The purposes of this study were to (i) compare involved (ACLR) versus uninvolved (contralateral) femoral trochlear cartilage T-2 relaxation times 6 months after ACLR, and (ii) determine the relationship between walking speed and walking mechanics 3 months after ACLR and femoral trochlear cartilage T-2 relaxation times 6 months after ACLR. Twenty-six individuals (age 23 +/- 7 years) after primary, unilateral ACLR participated in detailed motion analyses 3.3 +/- 0.6 months after ACLR and quantitative magnetic resonance imaging 6.3 +/- 0.5 months after ACLR. There were no limb differences in femoral trochlear cartilage T-2 relaxation times. Slower walking speed was related to higher (worse) femoral trochlear cartilage T-2 relaxation times in the involved limb (Pearson's r: -0.583, p = 0.002) and greater interlimb differences in trochlear T-2 relaxation times (Pearson's r: -0.349, p = 0.080). Walking mechanics were weakly related to trochlear T-2 relaxation times. Statement of clinical significance: Slower walking speed was by far the strongest predictor of worse femoral trochlear cartilage health, suggesting slow walking speed may be an early clinical indicator of future patellofemoral OA after ACLR.