Abstract
The reported rate of femoral stem fracture after total hip arthroplasty (THA) varies between less than 0.1 and 3.4%. The study aimed to evaluate the incidence of Lubinus SP II femoral stem fracture in our population and associated risk factors, and to examine clinical outcomes following revision THA for SP II stem fracture. 4244 primary THAs incorporating the anatomic femoral stem were identified within our institution from a prospectively compiled arthroplasty patient database. 5 patients presented with a broken Lubinus SP II anatomical hip stem. Immediately postoperatively, the operating consultant submitted intraoperative data detailing surgical approach, head size, and components used. Patients were reviewed 6 weeks postoperatively in an orthopedic clinic, then followed up at a dedicated orthopedic audit clinic at 6 months, 1, 3, and 5 years postoperatively, and data were collected prospectively. Postoperative complications were recorded at each follow-up visit. The incidence of stem fracture was 0.1% (5/4240) at a mean follow-up of 7.5 years. 3 were male, and 2 were female. The mean age was 63.8 years (range, 53-72, SD = 7.4). The mean weight was 109 kg (range, 88-128; SD = 14.2). The mean BMI was 36.5 kg m(-1) (range, 32.5-41.0, SD = 3.08). The mean time from primary THA to fracture was 6.4 years. The mean size of the cement restrictor (indirectly suggesting the femoral canal diameter) was 13.6 mm (range, 12-15, SD = 1.1). The implant neck angle used was 117 in 4 patients and 126 in 1 patient. The mean stem position in varus was -2.2 (range, -6-0, SD = 3.0). 4 fractures (80%) occurred at mid-stem and 1 (20%) distally with -6 degrees varus and a 15 mm cement restrictor. To minimize stem fracture risk, we recommend using as large a size stem as possible after sequential reaming in tight femoral canals and avoiding stem downsizing along with holistic postoperative management.