Heterotopic ossification (HO) is a common complication following total hip replacement with a number of papers reporting an incidence of greater than 40%. In an effort to reduce the degree of contamination of the abductor muscle bed with osteoprogenitor cells, we used a plastic protective shield during the preparation and reaming of the femoral head in the hope that this would result in a decreased incidence of HO.

One hundred and forty consecutive metal-on-metal resurfacing procedures (mean age 52.3 years) utilizing the Birmingham hip prosthesis were performed between March 1999 and May 2002. Pre-operative diagnosis included osteoarthritis (105), Dysplasia (19), AVN (8), Inflammatory arthropathy (8). In the first 70 cases wet swabs packed around the femoral head were used in an attempt to reduce bone contamination. For all subsequent cases, bone contamination was controlled by the use of the plastic shield. Patients were reviewed clinically and radiologically at a mean of 36.1 (range 24–62) months post operatively. Pre-operative and follow up radiographs were assessed for presence of HO according to the Brooker classification. Harris hip and UCLA activity scores were recorded pre- and post-operatively on all patients. Three patients were lost to follow up.

Eighteen patients (12.9%) were noted to have HO on follow up radiographs. Sixteen patients in the initial group when no shield was used developed HO (Brooker I [10], II [2] & III [1]). Only two patients developed HO (Brooker I) following introduction of the protective shield. This modification in surgical technique was statistically significant in decreasing incidence of HO. All patients with radiological abnormalities were asymptomatic. We propose that this protective shield should be used during resurfacing hip arthroplasty as prophylaxis against ectopic new bone formation.