Knee joint changes in patients with neglected developmental hip dysplasia: A prospective case-control study

•The affected knees had increased valgus angulation on the coronal plane.•The affected knees had increased posterior slope of distal femur and proximal tibia.•The unaffected knees also developed radiographic changes compared to control knees.

BackgroundFew reports are available describing knee changes in neglected developmental dysplasia of the hip (DDH). The purpose of this study was to assess the radiographic morphology of knee joints in adults with neglected DDH.MethodsThirty-seven patients (35 females and two males) with neglected DDH were prospectively recruited with an average age of 32.6 years. Twenty-three patients had unilateral and 14 patients had bilateral neglected DDH. Thirty-seven healthy individuals were recruited to form a matched control group. Three groups of knee joints were examined: affected knees (on the same side of the neglected DDH), unaffected knees (contralateral to the neglected DDH in patients with unilateral involvement), and control knees. A series of radiographic parameters of the knee joint were measured in the coronal and sagittal plane, and they were compared between patients and normal controls.ResultsIn the coronal plane, the affected knees had increased valgus angulation related to increased height of the medial femoral condyle, decreased height of the lateral femoral condyle and decreased lateral distal femoral angle compared to control knees. In the sagittal plane, both distal femoral and proximal tibial joints of the affected knees developed a decrease in posterior angles. Additionally, the unaffected knees also developed radiographic changes compared to control knees.ConclusionsPatients with neglected DDH may develop changes in both knee joints. These changes should be considered during surgery to the hip, femur and knee to prevent potential complications.Level of evidenceLevel 2.