[Titanium modular revision prosthesis stem in revision hip prosthesis]

Abstract

In revision arthroplasty of the hip, femoral defects and fractures must be bridged by a long stem. The implant has to be adapted exactly to the diameter of the cortical tube and has to be placed distally beyond the pathologic area. The titanium modular revision prosthesis (MRP) stem consists of the titanium alloy Ti6Al7Nb and is offered in various diameters, lengths, and special devices, which allows individual and load-stable reconstruction. The aim of the current study is to scrutinize first clinical and radiological results of the titanium MRP revision stem in revision arthroplasty of the hip. We report the midterm results of 130 non-cemented revision arthroplasties of the hip using the titanium MRP revision stem with a mean follow-up of 2.9 years (minimum: 1 year, maximum: 8 years), including 56 men and 74 women. The indication for revision arthroplasty was aseptic loosening of the cup and stem in 94 cases, loosening of the stem in 17 cases, reimplantation in a Girdlestone situation in 11, and periprosthetic fractures in 8 cases. The Harris hip score improved from 50.9+/-24.6 preoperatively to 88.5+/-11.5 postoperatively. The score according to Merle d'Aubigné improved from 9.8+/-4.0 preoperatively to 15.2+/-2.8 postoperatively. We found three recurrent dislocations, two lesions of the sciatic nerve, three cases of persisting deep infection, two periprosthetic fractures, and one case of subsidence of the stem of 2 cm required revision of the MRP stem. Atrophy of the proximal femur was visible in all cases with a stem diameter >17 mm (39/130). Stable primary fixation was achieved in 129 of 130 cases. The titanium MRP revision has proved to be a very reliable implant in cementless revision arthroplasty of the hip.