Cementless total hip replacement for hip dysplasia: anatomical hip center is associated with better patient-reported functional outcome

Background
Total hip arthroplasty in patients with dysplastic hips is a challenging procedure. The main goal of surgery is to achieve anatomical center of rotation to improve the abductor function, patient satisfaction, and implant survival. The aim of this study was to report the mid-term functional results using the Oxford hip score (OHS) after cementless total hip replacement (THR).
Patients and methods
This was a retrospective analysis of the prospectively collected data of patients who had a THR done at our institution with hip dysplasia. Between September 2011 and December 2019, a total of 23 consecutive patients (26 hips) with Crowe II–IV developmental dysplasia were treated with primary cementless THR. The mean age for patients included were 34.1 ± 15.2 years. Females were more than males. The left side was operated more than the right side, and there were three bilateral cases. The mean preoperative OHS was 21 ± 6.6 points.
Results
All patients were followed up for a mean of 3.4 ± 2.6 years (range, 1–11 years). None of the cases were lost to follow-up. The mean OHS improved significantly from 21.2 ± 6.6 points (range, 8–38) preoperatively to 40.9 ± 4.8 points (range, 28–48) in the final OHS (Z=4.45, P<0.001). Regarding the final OHS, both Crowe types II and III were better than Crowe type IV, and the difference was statistically significant. The functional leg length discrepancy improved from a median of 3 (0–7) cm preoperatively to 0 (0–3) cm postoperatively (Z=4.3, P<0.0001). All cases that required shortening were Crowe IV dysplasia (five cases). A total of 22 (88%) hips were reconstructed within 2 cm of the other hip.
Conclusion
Restoration of anatomic center of rotation as close as possible was associated with better functional outcome. Cementless fixation was possible in all cases.