Implant orientation, patient factors may influence squeaking after ceramic-on-ceramic THA

Patients who developed squeaking hips tended to be younger, heavier and taller than patients without squeaking.

Component orientation as well as certain patient-specific characteristics may predispose patients to experiencing audible squeaking after undergoing total hip arthroplasty involving ceramic-on-ceramic bearings, according to a study by Australian researchers.

William L. Walter, MBBS, FRACS, FAOrthA, and colleagues, reviewed demographic and other factors potentially related to implant squeaking in 17 patients who complained of such squeaking after receiving a ceramic-on-ceramic total hip arthroplasty (THA).

"All 17 cases were primary THAs; we have yet to witness squeaking in a ceramic-on-ceramic revision THA," the authors noted.

The researchers compared these patients to 17 control patients matched for primary diagnosis, type of implant, age, gender, height and weight, and who also received treatment within 6 months of the date of surgery. The researchers selected these patients from among 2,397 consecutive THAs involving ceramic-on-ceramic bearings treated by Walter and colleagues between 1997 and 2005 at Walter's practice in Sydney, according to the study, published in the Journal of Arthroplasty.

Of the 17 squeaking hips, 13 received surgery at the authors' practice and four had been referred from another center. Among these 13 hips, seven had been implanted with 32-mm diameter bearings and six had received 28-mm bearings.

"Comparing these patients with the remaining 2,384 patients with primary ceramic-on-ceramic THRs, patients with squeaking hips are, on average, younger, heavier and taller," the authors wrote.

Patients with squeaking hip averaged 179 cm in height, 90 kg in weight and 56 years of age. The 2,384 non-squeaking patients averaged 169 cm in height, 76 kg in weight and 65 years of age, according to the study.

Overall, hips began squeaking an average of 14 months after undergoing THA, ranging from 4 to 50 months.

Both control and squeaking hips had similar mean acetabular anteversions and acetabular inclinations. However, "the spread as indicated by the interquartile range and variance was greater in the squeaking hips than the controls," the authors reported.

Compared to control hips, squeaking hips had six times greater variance of anterversion and five times greater variance of inclination.

"When these data were represented graphically, the control hips form a cluster around 45° inclination and 25° anteversion, in contrast to the scatter of the squeaking hips. If we define the acceptable range to be between 15° and 35° of anteversion and between 35° and 55° of inclination, only six (35%) of the squeaking hips were in the acceptable range, whereas 16 (94%) of the control hips were in the range (P=.0003)," the authors reported.

"Therefore, if the acetabular orientation is outside this range, the hip is 29 times more likely to squeak," they wrote.

"Based on this study, we can conclude that an acetabular component placed within 10° of a target of 25° operative anteversion and 45° operative inclination ... will significantly reduce the chance of squeaking," they wrote.

However, "We are cautious to recommend this as an ideal range because the surgeon must also consider other factors when placing an acetabular component, including hip stability, boney support of the component and the local anatomy, which may be deformed.

"In any case, current technology does not allow the surgeon to reproducibly orient the acetabular component even if there were a numerical ideal," the authors noted.

For more information:
Walter WL, O'Toole GC, Walter WK, et al. Squeaking in ceramic-on-ceramic hips: The importance of acetabular component orientation. J Arthroplasty. 2007;22:496-503.