Modular hip implant fracture at the stem-sleeve interface

The use of modular implants in femoral stem design has grown increasingly popular over the last decade because of the theoretical advantage of more flexibility and optimization of femoral anteversion, limb length, and femoral component offset. With the benefit of increased surgical flexibility, however, modularity also carries the theoretical risks of fretting at the modular surfaces, sequelae of wear debris, and possible failure and fracture of the stem at the modular junction. Indeed, there have been an increasing number of reports of modular implants failing due to fracture at modular junctions. The S-ROM prosthesis (DePuy Orthopaedics, Inc, Warsaw, Indiana), however, has a stellar clinical record and has been used with good results in both primary and revision total hip arthroplasty. Only a single case of S-ROM failure at the stem-sleeve interface has been reported in the orthopedic literature. The aim of this case report was to present a succinct history of proximal modularity in total hip arthroplasty and to describe the only known case of this type of catastrophic failure in an S-ROM prosthesis with a metal-on-metal bearing. Despite a low level of serum metal ions on presentation, scanning electron microscopy showed findings consistent with corrosive processes and pseudotumor was seen at revision surgery.