Larger femoral heads may reduce dislocation rates in revision THA

Larger femoral heads may reduce dislocation rates in revision THA

Dr. Don Garbuz is the Co-Theme Leader, Surgical Solutions, at the Centre for Hip Health and Mobility (CHHM) as well as Associate Professor with the Department of Orthopaedics at UBC.

Dislocation rates can be significantly reduced in patients undergoing revision total hip arthroplasty by using a larger femoral head, according to a level 1 study presented here.

Donald S. Garbuz, MD, MHSc, shared his Frank Steinchfield Award-winning findings at the 2011 Hip Society/American Association of Hip and Knee Surgeons Combined Specialty Day Meeting.

The reduction in rates is paired with a lack of increase in linear polyethylene wear, Garbuz added. He said the results have convinced him and his group to routinely use large heads with a highly cross-linked polyethylene acetabular liner in all revision hip arthroplasties.

“Dislocation rates in the literature range from 7% to 20%, sometimes up to 25%, and it is the number one reason that a revision hip replacement will fail,” Garbuz said.

Superiority of the larger head
Garbuz and colleagues attempted to assess whether a larger femoral head — one measuring 36/40 mm — would increase dislocation rates when compared with a standard head of 32 mm. The secondary purpose of the study was to confirm that using a large cobalt-chrome head does not increase linear polyethylene wear in revision total hip arthroplasty.

The investigators randomized 184 patients undergoing total hip arthroplasty at seven centers to receive either a 32 mm head or a 36/40 mm head. The primary endpoint for the study was dislocation, and polyethylene wear was measured using radiostereometric analysis.

Baseline demographics were similar in the groups. The investigators analyzed quality-of-life measures and followed patients from 2 years to 5 years postoperatively.

Dislocation
The dislocation rate for the large head group was 1.1% vs. 8.7% for the 32 mm head. Furthermore, there was no reported difference in polyethylene wear between the groups. Quality-of-life outcomes were also similar.

“This study has clearly demonstrated the superiority of the large head in preventing dislocation in revision patients,” Garbuz concluded. “We recommend that we select the largest head available when patients are undergoing revision total hip arthroplasty.”

Reference:
Garbuz DS, et al. Dislocation in revision THA: Randomized clinical trial of 36/40mm vs 32mm head. Presented at the Hip Society/American Association of Hip and Knee Surgeons Combined Specialty Day Meeting. Feb. 19, 2011. San Diego.
Disclosure: Garbuz is a paid consultant for Zimmer, receives research support from DePuy and Zimmer as a principal investigator and is on the editorial/governing board of the Journal of Arthroplasty.