Accurate diagnosis of hip prosthesis loosening using a vibrational technique.

OBJECTIVE: To examine the potential role of vibration testing as a non-invasive method of diagnosing loosening of total hip replacements in the clinical setting.
DESIGN: Single blind cohort study in two hospitals.
BACKGROUND: Diagnosing loosening of total hip replacements is heavily dependent on investigative techniques that are unreliable. Previous studies into the use of vibration testing have produced conflicting results.
METHODS: Comparison of vibration testing and radiographs in patients with a total hip replacement experiencing hip pain symptomatic of loosening, with patients showing evidence of a secure prosthesis.
RESULTS: Vibration testing has a sensitivity of 80% and a specificity of 89%. The positive predictive value was 92% and the negative predictive value was 73%; it was unable to produce a definitive diagnosis in 8% of patients. When compared with radiographs from the same patients, vibration testing was shown to be 20% more sensitive and able to diagnose 13% more patients.
CONCLUSIONS: Vibration testing can deliver more accurate information on the stability of total hip replacements than radiographs in the clinical setting, despite being in the early stages of development. Relevance. This study shows that 70 more patients may be provided with the correct diagnosis and 46 fewer patients may be undiagnosed each year, when using vibrometry as opposed to radiographs. In view of the relative disparity between the level of development between the two techniques and the encouraging results hitherto presented, it is felt that by improving vibration testing it may supersede radiographs in the detection of prosthesis loosening.