American Academy of Orthopaedic Surgeons Annual Meeting

American Academy of Orthopaedic Surgeons Annual Meeting

Issue: June 2011
June 01, 2011
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Study identifies patient characteristics for squeaking hip implants

Issue: June 2011
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Patients with squeaking implants after primary total hip arthroplasty tend to be taller, heavier and younger, according to a recently presented study.

Study investigator William Lindsay Walter, MD, PhD, noted that patients with squeaking hips had a higher range of postoperative internal and external rotation compared with those who did not have audible squeaking, and the phenomenon was not associated with a significant difference in patient satisfaction or Harris hip scores.

More than 2,000 cases

Walter and his colleagues studied 2,406 primary ceramic-on-ceramic hip arthroplasties performed between 1997 and 2008 in patients with osteoarthritis. The investigators identified 74 squeaking hips (3.1%) out of the series and investigated patient factors associated with an increased incidence of squeaking.

“Two were subsequently revised for problematic squeaking,” Walter said during his presentation at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS). “Those are the only two hips out of 4,000 ceramic-on-ceramic bearings that we have had to revise for squeaking.”

Sixteen percent of patients reported squeaking while walking, but most patients reported squeaking upon bending. Overall, 63% of patients reported that their hips squeaked less than once per day, with 5% of patients reporting squeaking with every step — “when it becomes a clinical problem,” Walter said.

Patients with squeaking hips tended to be taller (5 feet 7 inches vs. 5 feet 6 inches), heavier (176.8 pounds vs. 168.4 pounds) and younger (60 years vs. 65 years old) compared with patients who had silent hips, according to an AAOS press release.

The investigators found that patients with these characteristics were “significantly more likely” to have hips that squeaked.

More mechanical demands

“When we looked at all of these patients, squeaking vs. silent hips, the patients with squeaking hips were younger, they were taller, and they were heavier,” Walter said. “This, we think, represents increased mechanical demands across the hip.”

The investigators also found that patients with squeaking hips were more active and, on average, just as satisfied with their results as patients with quiet hips.

“We present the largest series of squeaking hips with ceramic-on-ceramic bearings to date, and those who present with squeaking are younger, taller and heavier with a better range of movement — and they generally are happy patients,” Walter concluded, adding that implant and surgical factors, such as cup positioning and balance issues, are also likely to be important.

“I think there are also implant factors and surgical factors that are important,” he said. “You have to have a hard-on-hard bearing usually to produce a squeak. Thin shells and thin stems may be important because it is the metallic components that resonate, and they are driven by the friction with the ceramic component — and there are some, particularly the thin stem, where they have the narrow in the sagittal plane, I think that is probably important for them to be able to resonate.” – by Robert Press

References:
  • Walter WL, Sexton SA, Yeung E, et al. The role of patient factors in squeaking of ceramic-on-ceramic total hip replacements. Paper #526. Presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons. Feb. 15-19. San Diego.
  • www.aaos.org

  • William Lindsay Walter, MD, PhD, can be reached at the Mater Clinic Building, Suite 1.08, 3 – 9 Gillies Street, Wollstonecraft NSW 2065; (02) 8920 3388; email: bill.walter@hipknee.com.au.
  • Disclosure: Walter receives royalties from Stryker and DePuy, is a paid consultant for DePuy and has received research or institutional support from Stryker, Ceramtec and DePuy.