Outcome of surgical treatment of inter prosthetic fractures: A case series.

INTRODUCTION: Interprosthetic fractures occur between a total knee replacement and a femoral stem of either a hemiarthroplasty or total hip replacement. The number of interprosthetic fractures will increase as the number of joint replacements rises. There is currently a paucity of literature looking at the outcomes of interprosthetic fractures. Therefore, we performed a retrospective study to: (1) determine fracture union in patients following surgical treatment of a femoral interprosthetic fracture, (2) measure outcomes included mortality and complications.

HYPOTHESIS: Favoring bone fixation instead of prosthetic revision gives an acceptable rate of reoperation.

MATERIALS AND METHODS: A retrospective case note review of all interprosthetic femoral fractures admitted to a tertiary trauma centre over a 7-year period. There were 24 patients (4 males and 20 females) with a mean age of 82.3 (65-98). The initial operative procedure was a total hip replacement (THR) and a total knee replacement (TKR) in 19 patients, one THR and revision TKR, four hip hemiarthroplasty and TKR. There were 23 cemented femoral stems, and 1 uncemented femoral stem. The median time to surgery was 84hours. The median length of hospital stay was 16 days. Nineteen patients underwent open reduction internal fixation and 1 of these used a strut graft. Two patients underwent revision knee replacements and 3 underwent a revision hip replacement. All patients had at least 2 years clinical follow-up.

RESULTS: One patient died within 30 days of fracture, leaving 23 patients to assess bone union. Another patient died within 1 year of fracture. Three out of 24 patients (12.5%) suffered a complication that required further surgery. The fracture united in 19/23 (82.6%) of patients and the 2-year mortality rate was 5/24 (20.8%).

DISCUSSION: Interprosthetic fractures are complex fractures occurring in elderly patients with multiple medical comorbidities. Whenever possible bone fixation instead of prostehtic revision give a low rate of complication and reoperation. The surgical treatments are complex, but with a well-performed surgical technique and an adequate rehabilitation program can result in satisfactory outcomes.

LEVEL OF EVIDENCE: IV, retrospective case series.