Fracture of a Modular Femoral Neck After Total Hip Arthroplasty

Abstract

The use of modularity in femoral stem designs for total hip arthroplasty has increased substantially over the past several years. The theoretical advantages of this design include the optimization of femoral anteversion, limb length, and offset of the femoral component. We report on a previously unreported fracture of a modular femoral neck device. The patient was informed that data concerning the case would be submitted for publication, and he consented. A forty-nine-year-old man underwent a primary total hip arthroplasty of the left hip, in June 2005, because of degenerative osteoarthritis and received a size-4 PROFEMUR Z femoral stem (Wright Medical Technology, Arlington, Tennessee) and a 64-mm CONSERVE acetabular component (Wright Medical Technology). The patient was 6 ft 6 in (198 cm) tall and weighed 340 lb (154.2 kg). An anterolateral surgical approach was utilized, and the bearing surface chosen was metal on metal. This proximal femoral cementless component is a dual-tapered rectangular stem that has a modular neck. The modular neck has an oval taper distally that is inserted into the femoral stem at a fixed angle. This allows the surgeon to independently adjust the offset and length as it is available in six different neck geometries and two lengths. Five different head options, ranging from –3.5 mm to +10.5 mm, are also available with this design. The head and neck are connected by means of a standard 12/14 Morse taper. Both the femoral stem and the modular neck are manufactured from a titanium alloy (Ti-6Al-4V). The patient had a 56-mm head with a –3.5-mm neck length. The neck geometry was a long varus anteverted neck (AR/VV2). The patient was otherwise healthy. The postoperative course was uneventful, and he was pain-free within three months after the procedure. In January 2009 (four years postoperatively), the patient slipped on ice and fell …