Femoral Stem Survivorship in Dorr Type A Femurs After Total Hip Arthroplasty Using a Cementless Tapered Wedge Stem: A Matched Comparative Study With Type B Femurs.

BACKGROUND: There is a lack of understanding on relationship between the femoral geometry and outcomes of total hip arthroplasty (THA). We investigated clinical and radiographic outcomes of THA using a cementless tapered wedge stem in patients with Dorr type A proximal femoral morphology and compared with those of type B femurs at a minimum follow-up of 5 years.

METHODS: We analyzed 1089 hips (876 patients) that underwent THA using an identical cementless tapered wedge stem. We divided all femurs into 3 types (Dorr type A, B, and C). Type A and B femurs were statistically matched with age, gender, body mass index, and diagnosis by using propensity score matching. Clinical, radiographic results, and stem survivorship were compared between the matched 2 groups.

RESULTS: A total of 611 femurs (56%) were classified as type A, 427 (39%) as type B, and 51 (5%) as type C. More radiolucent lines around femoral stems were found in type A femurs (7.8%) than in type B femurs (2.5%) (P < .001). Patients with radiolucency showed worse Harris Hip Score (86.2 points) compared with those without radiolucency (93.0 points) (P < .001). The stem survivorship of type A femur (97.8%) was lower than that of type B femur (99.5%) (P = .041). The reasons for femoral revision in type A femurs were periprosthetic fracture (67%), aseptic loosening (22%), and deep infection (11%).

CONCLUSIONS: This study showed a higher rate of complications after THAs using a cementless tapered wedge stem in Dorr type A femurs than those performed in type B femurs.