Primary Total Hip Arthroplasty in Severe Dysplastic Hip Osteoarthritis With a Far Proximal Cup Position

Background: Developmental hip dysplasia is the most common cause of secondary hip osteoarthritis. Due to severe acetabular bone deficiency, cup positioning in total hip arthroplasty (THA) of dysplastic hips remains a surgical challenge. The aim was to analyze the functional outcome of far proximal cup positions in primary THA. Methods: Fifty patients (61 hips) with THA for severe dysplastic osteoarthritis and a far proximal cup position were included. Patients were divided according to the heights of the implanted cups with increasing vertical distance from the interteardrop line (group A: 55-65 mm, group B: 65-75 mm, group C: > 75 mm). Functional outcome was assessed at latest follow-up (38 +/- 16 months) by Lower Extremity Functional Score, Tegner Activity Score, and Harris Hip Score (HHS). Patients answered a Patient Satisfaction Questionnaire. Leg length discrepancy was estimated radiographically. Results: The Lower Extremity Functional Score significantly decreased in C (45.3 +/- 25) compared to A (66.7 +/- 15.3) and B (67.9 +/- 9.9). The Tegner Activity Score significantly increased in all subgroups from preoperative to postoperative (2.2 +/- 1.3 to 4.1 +/- 1.4; P <.05). The mean overall HHS was 89.3 +/- 14.7 (A: 89.5 +/- 14.3, B: 94.3 +/- 6.5, C: 78.3 +/- 22.1). The HHS domains of activity of daily life and gait were significantly reduced in C (P <.05). Patients described a high satisfaction level with the surgery. No significant differences were found with regard to preoperative and postoperative leg lengthening (P = .881). Neither dislocations, impingement problems nor neurologic complications were observed. Conclusion: Primary THA without any concomitant surgical interventions with a far proximal cup position offers a safe and effective treatment option in severe dysplastic hip osteoarthritis. (c) 2019 Elsevier Inc. All rights reserved.