Longitudinal analysis of the shape changes of the knee in patients with anterior cruciate ligament injuries

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s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S248 bearing femur and tibia. For the medial and lateral analysis, division was per the MRI Osteoarthritis Knee Score (MOAKS) (a line extending cranially/caudally from the lateral edge of the femoral notch, and for the patella to a point just lateral to thepatellar apex). (Fig.1) Pain.Weused the WOMAC pain sub-scale and defined the primary outcome of knee pain dichotomously as moderate to severe pain (scores 2–4) on any of the 3 weight-bearing (WB)WOMAC pain questions (pain onwalking, climbing stairs, standing), acquired at the same baseline OAI visit as the MRI scans. Individual questions and the composite WB pain score were tested for their associationwithBML volumeusing theWilcoxon rank sum test. Chisquare tests were used to compare the medial and lateral PFJ for the number of subjects (%) with BML, and BML volume (Wilcoxon rank sum). Results: The samplewas 84%white, 52%male andwere 90% K–L grade 2 and 3. Subjects with weight-bearing knee pain had greater median BML volume than those without weight-bearing knee pain for the weightbearing femur, trochlea femoris and patella, PFJ, but not the tibia. In the examination of each specific weight-bearing item, we found an association with greater BML volume and pain during stair-climbing for both the femur, tibia, tibiofemoral and patellofemoral joints, with the difference the greatest in the patellofemoral joint (Table 1).With respect to the distribution of BMLs in the PFJ, prevalence was slightly higher medially, and median BML size was larger (Table 2). Conclusion: This cross-sectional study in a sample of baseline OAI subjects provides evidence for a strong relationship between stair-climbing pain and BML volume in knee OA, particularly in the PFJ. Further, PFJ BML volume is at least as prevalent medially as laterally. PFJ BML volume may help explainmedial PFJ pain andhave implications for the role of PFJ inOA and be a potential treatment target. Further work on the longitudinal relationship between PFJ BML volume and pain is underway. Fig. 1. a Patellar subregions M-medial L-lateral; 1b – division between trochlea and WB femur.