Total hip arthroplasty in patients with angular proximal femoral deformities.

Aims: An angular proximal femoral deformity, in association with osteoarthritis (OA) of the hip, considerably increases the technical complexity of primary total hip arthroplasty (THA). The aims of this study were to determine the long-term implant survival, the risk factors for failure, complications, and clinical outcomes of contemporary primary THA in this difficult group of patients.

Methods: Our institutional total joint registry was used to identify 119 primary THAs performed in 108 patients with an angular proximal femoral deformity, between January 1997 and September 2017. The deformity was related to a previous femoral osteotomy in 102 THAs (86%), and developmental or metabolic disorders in 17 THAs (14%). A total of 62 hips (53%) had a predominantly varus deformity. The mean age of the patients was 44 years (SD 13), their mean BMI was 29 kg/m² (SD 6), and 70 (59%) were female. An uncemented femoral component with metaphyseal fixation was used in 35 THAs (30%), an uncemented femoral component with diaphyseal fixation in 34 (29%), an uncemented modular femoral component with a metaphyseal fixation sleeve in 29 (24%), and a cemented femoral component in 21 (18%). Simultaneous corrective femoral osteotomy was performed in 22 THAs (18%). Kaplan-Meier survival and Harris Hip Scores (HHSs) were reported. The mean follow-up was eight years (2 to 22).

Results: The ten-year survival free of femoral loosening, any femoral revision, any revision and any reoperation was 95%, 93%, 90%, and 88%, respectively. A total of 13 revisions were undertaken, for aseptic femoral loosening in three, fracture of the femoral component in two, dislocation in two, aseptic acetabular loosening in two, polyethylene liner exchange in two, and infection in two. A preoperative varus deformity was associated with a higher risk of any revision (hazard ratio (HR) 12.5, p = 0.020), and those with a simultaneous osteotomy had a higher risk of any reoperation (HR 3.6, p = 0.023). The mean HHSs improved significantly from 52 preoperatively to 82 at ten years (p < 0.001).

Conclusion: In the largest series to date of primary THAs in patients with hip OA and an angular proximal femoral deformity, we found a good ten-year survival free from any revision. Varus deformities, particularly those treated with a simultaneous osteotomy due to the magnitude or location of the deformity, had a higher rate of further surgery.