The use of ultrasound in acquisition of the anterior pelvic plane in computer-assisted total hip replacement

Abstract

We have evaluated in vitro the accuracy of percutaneous and ultrasound registration as measured in terms of errors in rotation and version relative to the bony anterior pelvic plane in computer-assisted total hip replacement, and analysed the intra- and inter-observer reliability of manual or ultrasound registration. Four clinicians were asked to perform registration of the landmarks of the anterior pelvic plane on two cadavers. Registration was performed under four different conditions of acquisition. Errors in rotation were not significant. Version errors were significant with percutaneous methods (16.2 degrees; p < 0.001 and 19.25 degrees with surgical draping; p < 0.001), but not with the ultrasound acquisition (6.2 degrees, p = 0.13). Intra-observer repeatability was achieved for all the methods. Inter-observer analysis showed acceptable agreement in the sagittal but not in the frontal plane. Ultrasound acquisition of the anterior pelvic plane was more reliable in vitro than the cutaneous digitisation currently used.

Reply to the Letter to the Editor: Editor's Spotlight/Take 5: No Benefit after THA Performed with Computer-assisted Cup Placement: 10-year Results of a Randomized Controlled Study

“…As mentioned by Dr. Leopold in his Editor's Spotlight [5], we can either perform prospective randomized studies powered for a particular goal or do larger studies with less robust study design and larger sample size. These limitations have been clearly outlined in our paper [9].…”

“…But the acquisition of this plane is done percutaneously during the surgery [7,8]. In a previous cadaveric study [9], we demonstrated that the percutaneous acquisition in patients who are obese may lead to more than 10°of inaccuracy on the final cup anteversion. This variance is likely due to the difference of the soft-tissue thickness between the iliac spines and the symphysis in patients who are obese [9].…”

“…T hank you for giving us the opportunity to answer the Letter to the Editor concerning our recently published paper on computer-assisted cup placement in THA [9]. I must start by saying I have considerable respect for Dr. Dorr, who is an excellent surgeon and a visionary in hip reconstructive surgery.…”

Accuracy of acetabular cup placement in computer-assisted, minimally-invasive THR in a lateral decubitus position

“…This procedure remains an important source of inaccuracy in imageless navigation systems. In a previous cadaver study different conditions of landmark acquisition were investigated [18]. Percutaneous registration methods with and without draping showed a significant error in cup anteversion but not in inclination.…”

“…The results in this study suggest that the bias regarding anteversion could be avoided by applying a semi-invasive registration technique by puncturing the skin to obtain bony contact to the pubic bone near the pubic tubercles. Alternatively, ultrasound acquisition of the ASIS might be helpful [18].…”