Better range of motion, less wear possible with regular use of 32-mm femoral heads

Amar S. Ranawat

PARK CITY, Utah — At the Joint Arthroplasty Mountain Meeting, a presenter who is a proponent of and uses 32-mm femoral heads in total hip arthroplasty made the case for this size because it is associated with lower wear and dislocation rates compared with larger or smaller femoral heads.

Amar S. Ranawat, MD, said, “It is probably the best size, if you can use it on a regular basis.”

Although there are some positive results shown with larger-sized femoral heads, such as 36-mm heads, he noted there are also questions regarding their long-term performance and other issues.

“With regard to range of motion, the bigger the head size, the better your head-neck ratio. It increases your range of motion, but then we know there’s a limit to that ratio and that after 36 [mm], the range of motion doesn’t increase sufficiently. So, 32[-mm heads] may be a sweet spot in that area,” Ranawat, of Hospital for Special Surgery, said.

Regarding dislocation after THA, he said, “if you go up in head size, you will improve your dislocation rates. A 32 [mm] and 36 [mm] have been shown to be better than 28s in that regard.”

“In general, the 32 mm gives excellent range of motion, a low dislocation rate, low wear [and] a low incidence of groin pain, ... but we still need the full gamut of all head sizes,” Ranawat said.

Data show 32-mm femoral heads are widely used today, according to Ranawat.

“What I do when I need a larger cup is, I use 36-mm Biolox (CeramTec) heads,” he said. – by Susan M. Rapp

Reference:

Ranawat AS. The 32-mm femoral head is all you need. Presented at: Joint Arthroplasty Mountain Meeting; Feb. 10-13, 2019; Park City, Utah.

Disclosure: Ranawat reports he is a paid consultant for Arthrex; is a paid consultant for and receives research support from CeramTec; receives stock or stock options from ConforMIS; receives IP royalties and other financial or material support from and is a paid consultant for DePuy; is a paid presenter or speaker for Mako and Convatec; receives stock or stock options from Strathspey Crown; receives IP royalties, research support and other financial or material support from and is a paid presenter or speaker for Stryker.