Conversion of failed hemiarthroplasty to total hip arthroplasty: a short to mid-term follow-up study

The conversion of hemiarthroplasty (unipolar or bipolar) of the hip to total hip replacement has been reported to be associated with very high rates of intra- and postoperative complications. We present a prospective analysis of the outcome of conversion surgery in patients with failed hemiarthroplasty.

Forty-four cases, 30 women and 14 men, average age 62 years (range 42-75 years) of failed hemiarthroplasty were converted to total hip replacement between January 1998 and December 2004. Groin pain was the main presenting complaint in the majority of the patients (24 out of 44). Six patients had infection and were operated with staged procedure. All acetabular and the majority (86.5%) of femoral components used in our series were uncemented.

After an average follow-up of 6.4 years (range, two to nine years) Harris hip scores improved from 38 (range 15-62) preoperatively to 86 (range 38 to 100) and 22 (50%) patients were community ambulators without support while 17 (38%) needed minimal support of cane. Fifteen out of 18 (83%) patients who had isolated groin pain preoperatively experienced no pain postoperatively while three patients (17%) reported only partial improvement. Intraoperative and postoperative complications included iatrogenic fracture of the femur in two, femoral perforation in two, partial trochanteric avulsion in two, fracture of the acetabular floor in three hips, and postoperative dislocation in one. None of these complications resulted in a poor long-term outcome. The rate of loosening in our series was 2.3% (one out of 44) after a mean follow-up of 6.4 years with a mean survival of 97.4% at 72 months.

Conversion of symptomatic hemiarthroplasty to total hip arthroplasty is a safe option that gives good functional results, with marginally higher rates of intra-operative complications. The patients should be warned of the possibility of incomplete relief of groin pain postoperatively.