Surgeons’ Accuracy in Achieving Their Desired Acetabular Component Orientation

Abstract

Surgeons overestimate operative inclination and underestimate anteversion, which is of benefit, as this, on average, helps to achieve the desired radiographic cup orientation. Although the use of visual cues helps, conventional techniques result in a large variability in acetabular component orientation. New and better guides and methods for training need to be developed.

Operative and radiographic acetabular component orientation in total hip replacement: Influence of pelvic orientation and surgical positioning technique

“…Measures for apparent operative, true operative, radiographic, and neutralised radiographic acetabular orientation were obtained from the model. Variation in TAL version [24], surgical error [23] and pelvic orientation [9] were incorporated into the models to induce variation in the aforementioned measures. For each factor, normal distributions were fitted to clinical data from the literature and sampled randomly (n = 1,000).…”

“…Meermans et al [26] concluded that the TAL method was better at controlling radiological version based upon their radiographic outcomes being within the Lewinnek target zone. 21 Natural variation of TAL, [23] along with the natural variation in pelvic tilt, [13] may result in greater inter-patient variability with respect to measured radiological version. In this study, patientspecific targets for NRI and NRV were calculated.…”

“…If we were to include multiple mappings, duplicate pelvic positions would result, which may bias the data and subsequent observations from this study. A limitation of the theoretical model was that it was based on clinical data from a limited number of institutions [9,23,24]. For example, the extent of pelvic mal-positioning may be influenced by the type of intraoperative patient support.…”

“…inclination (SEMAGI , -3 ± 5°) were based on an assumed normal distribution defined by mean and standard deviation error values from an experimental study of surgical accuracy [23]. The resultant position of the acetabular cup axis for the MAG approach (ıM) was obtained using Equation 2, which orientated the introducer such that it matched Murray's definitions for operative acetabular orientation.…”

“…A custom solver, Equation 5, was developed to determine the angle ( ) that the acetabular cup axis for the TAL method (T) would have to rotate about the � R axis to provide an AOI of 45°, between the introducer and theatre floor (T xz ; Figure 5). Surgical errors for the TAL method (SETALI, -3 ± 5°, and SETALV, 0 ± 7°) were based on the findings of Grammatopoulos et al [23]. This in turn provided the resultant intra-operative location of the acetabular cup axis when using the TAL approach (T).…”