ENDOPROSTHETIC REPLACEMENT OF THE DISTAL FEMUR: THE 30 YEAR RESULTS

Abstract

We have investigated whether improvements in design have altered the outcome for patients undergoing endoprosthetic replacement of the distal femur following tumour resection.

Survival of the implant and ‘servicing’ procedures have been documented using a prospective database and review of the implant design records and case records. A total of 335 patients underwent a distal femoral replacement with 162 having a fixed hinge design and 173 a rotating hinge with most of the latter group having a hydroxyapatite collar at the bone prosthesis junction. The median age of the patients was 24 years (range 13-82 yrs). With a minimum follow up of 5 years and a maximum of 30 years, 192 patients remain alive with a median follow-up of 11 years. The risk of revision for any reason was 17% at 5 years, 34% at 10 years and 58% at 20 years. One in ten patients developed an infection and 42% of these patients eventually required an amputation. Aseptic loosening was the most common reason for revision in the fixed hinge knees whilst infection and stem fracture were the most common reason in the rotating hinges. The risk of revision for aseptic loosening in the fixed hinges was 32% at ten years compared with nil for the rotating hinge knees with a hydroxyapatite collar. The overall risk of revision for any reason was halved by use of the rotating hinge, and for patients older than 40 years at time of implant.