Differences in knee joint degeneration between primary hip osteoarthritis and hip osteoarthritis secondary to hip developmental dysplasia: A propensity score-based analysis.

The prevalence of knee OA and lower-limb malalignment on the ipsilateral side of hip OA were different for PHOA and DDH-OA patients. Shifting the mechanical axis of lower limbs might be associated with the prevalence of knee OA and lower limb malalignment in the presence of unilateral hip OA.