An Analysis of the Potential Relationship between Crowe Type and Lower Extremity Morphology in Patients with Developmental Dysplasia of the Hip

PURPOSE: To test whether Crowe type is related to femoral alignment and leg length discrepancy by evaluating the preoperative lengths and coronal alignment of femurs, pelvic parameters and hip morphology of patients who underwent primary hip arthroplasty due to coxarthrosis secondary to developmental dysplasia of the hip (DDH). MATERIALS AND METHODS: Medical records of patients with coxarthrosis secondary to DDH who were treated with total hip arthroplasty at Department of Orthopaedics and Traumatology, Istanbul University Faculty of Medicine between 2008 and 2017 were reviewed. The mechanical axis of lower limbs was analyzed; pelvic height and femoral and tibial lengths were measured. All femurs were classified according to the Dorr classification. RESULTS: A total of 97 patients were eligible for analysis and were diagnosed with unilateral DDH (n=51) or bilateral DDH (n=46). In those diagnosed with unilateral DDH, the affected pelvis, femur, and tibia were often shorter than the unaffected side. In those diagnosed with bilateral DDH, femoral and pelvic lengths were unpredictable. In the femoral coronal alignment test, data varied widely but were within normal limits. The difference in the Dorr types of femurs was significant between dysplastic and normal sides of patients with unilateral DDH (P=0.001) but not those with bilateral DDH. CONCLUSION: Especially in patients with unilateral DDH, pelvic heights and femoral and tibial lengths on the affected side may be shorter compared with unaffected side regardless of the Crowe type. Femoral coronal alignment is unpredictable for both groups. Careful preoperative analyses of femoral coronal alignment and pelvic length are advised.