To investigate the clinical and radiographic outcomes of uncemented total hip arthroplasty with and without screw fixation.

A retrospective analysis of 114 patients(117 hips) with cementless total hip arthroplasty performed from August 2009 to August 2015 was carried out. The patients were randomized into group A without adjunctive screw fixation (n=59) and group B with screw fixation (n=58). Consecutive radiographs were compared to evaluate acetabular stability at the 3^rd month, 12^th month, 24^th month postoperatively and at the last follow-up. Harris hip scores and radiological outcomes were analyzed. Fifty-seven hips in group A and 56 hips in group B were available for complete clinical and radiographic analysis. The Kaplan-Meier survivorship analysis was used to estimate the survival of the prothesis in the two groups.

The mean follow-up period was (5.7±1.6) years. The mean surgery duration and operative bleeding was less in group A than in group B(t=2.213, P<0.05, t=2.342, P<0.05 respectively). At the last follow-up, the Harris scores were (95.0±2.1) in group A and (93.0±5.5) in group B (P=0.693) . Radiolucent lines were seen in four hips(7.0%), three hips(5.3%), one hip(1.8%)in group A and one hip(1.8%), two hips(3.6%), two hips(3.6%)in group B at the 3^rd month, 12^th month and 24^th month after surgery respectively. Osteolysis and migration were found in one hip in group A and 2 hips in group B. Kaplan-Meier survivorship at mean (5.7±1.6) years follow-up was 97% in group A and 95% in group B with radiographic loosening as the end point(P>0.05).

Additional screw fixation in principle is not necessary in press-fit cups, especially when there is no acetabular bone defect.