Development of a non-invasive diagnostic technique for acetabular component loosening in total hip replacements

Abstract

Current techniques for diagnosing early loosening of a total hip replacement (THR) are ineffective, especially for the acetabular component. Accordingly, new, accurate, and quantifiable methods are required. The aim of this study was to investigate the viability of vibrational analysis for accurately detecting acetabular component loosening. A simplified acetabular model was constructed using a Sawbones(®) foam block. By placing a thin silicone layer between the acetabular component and the Sawbones block, 2- and 4-mm soft tissue membranes were simulated representing different loosening scenarios. A constant amplitude sinusoidal excitation with a sweep range of 100-1500 Hz was used. Output vibration from the model was measured using an accelerometer and an ultrasound probe. Loosening was determined from output signal features such as the number and relative strength of observed harmonic frequencies. Both measurement methods were sufficient to measure the output vibration. Vibrational analysis reliably detected loosening corresponding to both 2 and 4 mm tissue membranes at driving frequencies between 100 and 1000 Hz (p < 0.01) using the accelerometer. In contrast, ultrasound detected 2-mm loosening at a frequency range of 850-1050 Hz (p < 0.01) and 4-mm loosening at 500-950 Hz (p < 0.01).

Altering the Course of Technologies to Monitor Loosening States of Endoprosthetic Implants

“…The bone-implant integration failures are noticed in a large frequency range (up to 2000 Hz), and harmonics can emerge exceeding 100 Hz apart from the fundamental frequency. (T1-L2) Alshuhri et al [33,34] also proposed a totally noninvasive technology to detect loosening of the acetabular component in total hip replacements. An extracorporeal shaker, in the femoral lateral condyle, and two extracorporeal accelerometers, in the iliac crest and greater trochanter, are required to monitor acetabular cup loosening, which is analyzed by computing the harmonic ratios (relative magnitude of the first harmonic to the fundamental frequency) in the output signal.…”

“…Depiction of the technology T1-L2 of the 1st method of uncemented fixations for both vibrometric and acoustic approaches, illustrating a mini-shaker providing the input excitation signal, the reading components (ultrasound probe and accelerometer), and the acetabular cup. Reprinted from [33] with permission from Elsevier.…”

“…Different fixation scenarios can also be identified by damping analyses: increasing dampened outputs were observed for increasing stabilities. (T1-L2) The research team of Alshuhri et al [33,34] reported an alternative technology to the one previously described in the vibrometric approach to detect the acetabular component loosening for uncemented fixation, also depicted in Figure 2. The only difference concerns the use of an extracorporeal ultrasound probe instead of an accelerometer.…”

“…An increase in the harmonics magnitude can be observed with increasing acetabular cup loosening. Adapted from the work in[33] with permission from Elsevier. (T1-L3) Goossens et al[56] engineered a custom-made technology to monitor the fixation states of the acetabular component of hip implants.…”

Ex Vivo Evaluation of Cementless Acetabular Cup Stability Using Impact Analyses with a Hammer Instrumented with Strain Sensors

“…However, much less studies have been carried out to investigate the stability of the acetabular cup (AC) implant. Vibrational analyses were used to detect the AC loosening [ 22 , 23 , 24 ] and the implant stability [ 25 ]. Recently, a technique based on the analysis of the sound produced by the impact between the hammer and the ancillary was developed in order to control the AC fixation [ 26 ].…”