Radiographic Subsidence in Asymptomatic Patients After THR Using the Furlong Active HAP Stem

The short, tapered, collarless Furlong Active stem has been recently associated in the published literature with significant subsidence using Roentgen stereophotogrammetric analysis.

The purpose of this study was to analyze the short-term radiographic subsidence in Furlong Active HAP stems and correlate the results with the age, gender, bone morphology, and bone quality of the proximal femur, stem diameter, and medullary canal filling.

Sixty-five consecutive patients (70 hips) receiving the Furlong Active HAP stems were enrolled in this prospective series. The average follow-up was 2.99 ± 1.38 years. All patients were evaluated clinically using the Harris Hip Score (HHS) and radiographically for femoral stem subsidence. In addition, proximal femoral osteopenia, proximal femur morphology, and medullary canal filling were also evaluated.

The average subsidence was 2.4 mm (from 0 to 13 mm) at the end of the follow-up period. The average HHS score at the end of follow-up was 90 (range, 81-98). There was one intraoperative fracture.

Of the Furlong Active stems 61% subsided with initial weight bearing. Subsidence is higher in males, but no correlation has been found with age, stem diameter, morphology, osteopenia, or canal filling.