Mid-Term Results of the SL-PLUS Femoral Prosthesis The Influence of Femoral Bone Type.

BACKGROUND: Cementless fixation of the femoral stem has been shown to be durable and predictable in total hip arthroplasty (THA), primarily as a result ofrecent improvements in prosthesis geometry and porous surface. Although patients with osteoporotic bone have been considered poor candidates for the use of a cementless femoral component, some recent studies have indicated satisfactory results. However, the indications and selection criteria of cementless stems based on the morphology of the femoral canal have not been established.

PURPOSE: We aimed to assess and compare the mid-term results of cementless THA with an SL-PLUS® femoral component in patients classified as Dorr types A, B, and C.

METHODS: We evaluated the clinical and radiographic results of primary THA with the cementless SL-PLUS® stem for 34 hips (25 patients). The preoperative femoral bones were classified as Dorr types A, B, and C in 12, 15, and 7 hips, respectively. Implant survival rates were calculated, hip function was evaluated using the Japanese Orthopaedic Association hip score, and radiographic signs were determined from anteroposterior radiographs.

RESULTS: The mean follow-up period was 9.4 years (range: 7 to 13 years), and the mean Japanese Orthopaedic Association hip score improved from 43.8 points preoperatively to 85.3 points at the latest follow-up. The overall implant survival rate was 100% at 10 years; radiographic loosening or revision for any reason was used as the endpoint. Third and fourth degrees of stress shielding were observed in 29.4% of cases and were found to be significantly associated with a low cortical index, a Dorr type C femur, and a larger stem size.

CONCLUSIONS: The use of the SL-PLUS® stem provided satisfactory mid-term clinical and radiographic results in patients with any type of femoral canal morphology.