Lower extremity and spinopelvic alignment changes after total hip arthroplasty in unilateral Crowe III-IV dysplasia: clinical and radiological outcomes

Abstract

Objective: This study aimed to evaluate the short-term clinical and radiological outcomes of lower extremity and spinal changes following total hip arthroplasty (THA) in patients with unilateral Crowe type III and IV hip dysplasia. Methods: This prospective study included patients who have Crowe type III and IV hip dysplasia evaluated at a high-volume arthroplasty center. Demographic and surgical characteristics were documented. Clinical assessments included the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12 (SF-12), Kujala Score, Oxford Knee Score, Oswestry Disability Index (ODI), Roland-Morris Questionnaire, American Orthopedic Foot and Ankle Society (AOFAS) Score, and Foot and Ankle Disability Index (FADI). Radiological assessments included standing anteroposterior (AP) pelvis, AP leg length, and standing/seated lumbosacral AP and lateral radiographs preoperatively and at 1-year postoperatively. Results: Thirty-three patients (mean age 52.7 +/- 11.8 years) were followed for an average of 18.3 +/- 7.0 months. Significant improvements were observed postoperatively in HHS and WOMAC scores for both ipsilateral and contralateral hips, SF-12, ODI, Roland-Morris, and ipsilateral knee WOMAC scores (all P<0.05). Radiologically, postoperative improvements included a significant reduction in leg length discrepancy (P<0.001), medial mechanical axis deviation on the ipsilateral side (P<0.001), increased joint line convergence angle and ankle joint line orientation, and spinopelvic alingment with increased sacral slope (P=0.027) and decreased lumbar lordotic angle (P<0.001). Conclusion: Unilateral high-grade hip dysplasia, when treated with total hip arthroplasty (THA), results in significant short-term improvements in clinical outcomes and lower extremity alignment. In patients with an average follow-up duration of 18.3 +/- 7.0 months, although the valgus deformity on the operated side improved, neutral alignment was not achieved. The contralateral limb remained in varus alignment. While spinopelvic parameters remained within normal limits, significant changes were observed in sacral slope and lumbar lordosis.