Distally locked, fully hydroxyapatite coated modular long stems in salvage revision hip arthroplasty: a report of early experience

Introduction

Revision hip arthroplasty can sometimes be very challenging due to poor proximal bonestock following multiple revisions, bone resorption, infection or peri-prosthetic fracture. The challenge for the surgeon is to achieve fixation of the implant distally in healthy bone, yet allow bone in-growth proximally to encourage regeneration of the deficient femur. We present our early experiences with a fully hydroxyapatite coated modular long stems with distal screw locking (REEF, Depuy) in difficult revision scenarios.

Methods

A total of 21 patients with a mean age of 68 (range 37–86) were followed up for a mean period of 19 months (9–36 months). Revision was performed for aseptic loosening with severe proximal bone loss in 14 cases (67%), peri-prosthetic fractures in 6 cases (28%) and 1 case with infection (5%). Oxford hip score was determined for each patient. Radiographs were assessed for the formation of spot welds, cortical hypertrophy, radiolucent lines, subsidence of implants, calcar resorption and heterotopic ossification.

Results

One patient underwent re-revision due to initial undersizing of the stem. Radiological review of all the femoral components, including the one re-revision showed stable bony in-growth and no radiolucent lines in any zone. The incidence of spot weld formation and cortical hypertrophy was highest in zone 6. One patient had persistent thigh pain and subsidence of 2 cm occurred in one case (5%). There were no dislocations, infections or calcar resorption. Three patients developed Grade 1 and three patients developed Grade 2 heterotopic ossification.

Conclusion

Improvement in stem design, surface coating, distal locking and modularity allow independent fitting of the diaphysis and metaphysis, adjustment of length, offset and version to facilitate more biological reconstruction of proximal femur. Early results with this stem in salvage revisions appear promising.