You might expect a squeak or two from a new pair of shoes, but from a new total hip? At the recent fall meeting of the American Association of Hip and Knee Surgeons (AAHKS), attendees watched—and heard—videos of patients who had received ceramic-on-ceramic (COC) total hip arthroplasties (THA). As the patients walked, climbed stairs or sat, a distinct squeaking sound emanated from their hips.
The videos were presented along with two separate studies—one prospective, the other case-controlled—reporting on this unusual phenomenon.
An underreported phenomenon
Christopher A. Jarrett, MD, reported on a prospective study involving 143 patients (159 COC THAs), 10 of whom (7 percent) experienced squeaking. An additional 31 patients (20 percent) reported that their new hips made noises other than squeaks. Although there were no reports of squeaking in the control group of 48 patients (60 THAs) who received metal-on-polyethylene implants, patients reported other noises in two cases (4 percent).
Patients could reproduce the squeaking during mid-range motion while load bearing, as in a simulated stair climb. No patient associated any pain with the squeaking, and average Hip Society Scores (HSS) increased from 19.8 preoperatively to 38.4 postoperatively.
“Only one of the squeakers in our series complained about the noise,” reported Dr. Jarrett. “We found the others by polling out patients. Our radiographic analysis found no correlation between cup position and squeaking, nor between anteversion and squeaking.
“In the entire series, there has been only one revision—for recurrent dislocation—in a patient who happened to be a ‘squeaker,’” he continued. “One other squeaker is considering revision, because he squeaks with every step, which is having a negative effect on his quality of life.”
The study involved three surgeons and all surgeries were performed between March 2003 and May 2005. The squeaking hip is a peculiar phenomenon unique to hard-on-hard bearing services. The immediate and long-term implications of squeaking and noises have yet to be studied fully. The discussion following the presentation focused on the possibility that technical problems, including microseparation or component malpositioning, could be the reason for the squeaking hips.
The result of component malpositioning?
The second study, presented immediately afterward, addressed the issue of component malpositioning as a potential cause for squeaking in COC THAs. This case-controlled study matched 30 patients who had squeaking COC THAs in a one-to-two ratio with patients whose COC THAs did not squeak. Matching criteria included age, gender, body mass index, surgeon, date of surgery, prosthesis type, femoral head size, and acetabular liner size.
Richard H. Rothman, MD, and his colleagues performed radiographic evaluations to determine the position of the acetabular component. In addition, a computed tomography (CT) scan was used to assess component positioning in the patients who had squeaking COC THAs. No such assessment was performed for the control group, due to ethical and cost considerations.
The radiographic evaluation found no statistically significant difference in the mean club inclination (p = 0.27) or in cup version (p = 0.69) between squeaky and quiet hips. The mean values for cup version and inclination obtained with the CT scan did not significantly differ from the radiographic measurements, verifying the accuracy of the software used to perform the evaluation,
In the discussion afterward, the researchers reported that the total incidence of squeaking hips at their institution was 2.7 percent (30 of 1,056 COC THAs) from 2002 to 2005. During the first year, the incidence of squeaking hips was 1 percent (1 of 99); the incidence increased to 3 percent (13 of 388) the following year, and dropped slightly (16 of 567) in the third year. Among patients who had bilateral COC THAs, five experienced squeaking on one side, and two had squeaking in both hips.
“The main etiology of squeaking COC THAs remains elusive,” said Dr. Rothman. “Although component malpositioning and impingement could potentially be an important contributing factor, the latter cannot be the sole reason for noisy ceramic hips based on the findings of this study. Further investigations to elucidate the etiology of this undesirable complication are warranted.”
“The Squeaking Hip: An underreported phenomenon of ceramic-on-ceramic total hip arthroplasty” by Christopher A. Jarrett, MD; Amar S. Ranawat, MD; Matteo Bruzzone, MD; Jose Rodrigues, MD, and Chitranjan Ranawat, MD, and “Noisy Ceramic Hips: Is component malpositioning the problem?” by Camilo Restrepo, MD; Javard Parvizi, MD; James Purtill, MD; Peter Sharkey, MD; William Hozack, MD; and Richard H. Rothman, MD, were presented at the 16th annual AAHKS fall meeting, Nov. 3 – 5, 2006. The paper presenters reported no conflicts of interest.