Abstract
Background: Recently, the new phenomenon of “squeaking” noises emitted from THAs with ceramic-onceramic bearings has spared international interest. It shows a frequency of 0,7–19,5% in literature, but infrequently requires revision surgery. However, an even higher incidence of various other noises from those THAs audible to the human ear have become popular in the process: this noise can resemble clicking, grinding or creaking and can be caused by distinct movements, during longer periods of walking, or can be constant with movement. The incidence of those noises can reach up to 30% of THAs. However, memory has faded that other bearings like metal-on-metal and PE/ceramic have been associated with noises in the past.
Therefore we aimed to investigate the occurence of acoustic emissions in patients, who had all received the same implant but with alternate bearings, to investigate the nature of noise, duration and clinical consequence for all 3 bearings (polyethylene/ceramic, metalon-metal, ceramic-on-ceramic).
Method: Between 1999–2001, 360 patients were matched in a prospective randomised trial. All of them received a cementless Zimmer© Alloclassic Variall™ implant at the Orthopaedic Hospital Vienna – Speising, Austria with either a ceramic-on-ceramic bearing, a metal-on-metal bearing or a polyethylene/ceramic bearing. A questionnaire was sent via mail, including questions on first occurence of hip noise, information on the kind and duration of the phenomenon and possible adverse evaluation on behalf of the patient. In case of a positive report, the patient was invited to a clinical examination and radiographic analysis. In addition, a specialised audiography was conducted in patients with audible sensations. Finally, the SF-36 and WOMAC were analysed. A number of patients received further examination with methods of gait analysis in order to detect the distinct point of occurence of the noise during the gait cycle.
Results: 33 patients reported an audible phenomenon from their THA, 14 received a ceramic-onceramic bearing (Cerasul), 13 a polyethylene/ceramic bearing (Durasul) and 6 a metal-onmetal bearing (Metasul). The most common noise was a distinct clicking, followed by a creaking noise. Only 1 patient reported a squeaking sensation, he received a polyethylene/ceramic bearing.
Conclusion: The emission of specific noises from THAs of all bearings has been well documented in recent trials and could be verified in this survey of cementless THAs. No trend towards an increased incidence of noise from THAs with ceramic-on-ceramic bearings could be detected. Interestingly, the single case of „squeaking” was reported from a patient with polyethylene/ceramic bearing. Microseparation and subluxation of the femoral head with resulting edge loading and formation of stripe wear has recently been suspected as the main cause for “noisy hips.” So far 2 ceramic-on-ceramic hips of this study group population have been revised. Both articulations showed areas of stripe wear due to subluxation of the joint.
Correspondence should be addressed to Diane Przepiorski at ISTA, PO Box 6564, Auburn, CA 95604, USA. Phone: +1 916-454-9884; Fax: +1 916-454-9882; E-mail: ista@pacbell.net
