Imageless navigation for insertion of the acetabular component in total hip arthroplasty

Abstract

In a prospective randomised clinical study acetabular components were implanted either freehand (n = 30) or using CT-based (n = 30) or imageless navigation (n = 30). The position of the component was determined post-operatively on CT scans of the pelvis. Following conventional freehand placement of the acetabular component, only 14 of the 30 were within the safe zone as defined by Lewinnek et al (40 degrees inclination sd 10 degrees ; 15 degrees anteversion sd 10 degrees ). After computer-assisted navigation 25 of 30 acetabular components (CT-based) and 28 of 30 components (imageless) were positioned within this limit (overall p < 0.001). No significant differences were observed between CT-based and imageless navigation (p = 0.23); both showed a significant reduction in variation of the position of the acetabular component compared with conventional freehand arthroplasty (p < 0.001). The duration of the operation was increased by eight minutes with imageless and by 17 minutes with CT-based navigation. Imageless navigation proved as reliable as that using CT in positioning the acetabular component.

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

“…With the patient in the lateral decubitus position, it is difficult to be sure about the precise orientation of the pelvis [12], and this may compromise the registration of the contralateral anterior superior iliac spine for referencing the anterior pelvic plane. Our data confirms that a significantly lower variability for the minimally invasive acetabular cup position can be obtained by using navigation [3,13,14], even when using a minimally invasive technique [5,15,16]. Our data confirms that cup anteversion is generally less accurate than cup inclination with the imageless navigation technology [17].…”

“…According to the results of previously published data [3], standard deviation of inclination and anteversion measurements are expected to be about 4°and 6°for navigation and about 7°and 14°for non-navigated methods, respectively. This translates to a least expected ratio of variances of 7 2 /4 2 =3.…”

“…Accordingly, the use of computer navigation in total joint arthroplasty has become more prevalent and the method has proved to be reliable for acetabular component positioning. Studies showed higher accuracy in plastic pelvis models [1], in human cadaver models [2] and in clinical use [3]. While there are some randomised controlled trials comparing the use of computer navigation with freehand component placement in a supine position [4], there is, so far, only one randomised study referring cup position to postop 3D computed tomography (CT) measurements in a lateral decubitus position using imageless navigation and a minimally-invasive approach [5].…”

Six Sigma Analysis of Minimally Invasive Acetabular Arthroplasty: A Preliminary Investigation

“…For computer navigation, the APP was determined. Recent studies have advanced the use of this structure because of the definable landmarks presented [19,26,29,35,37,43]. For purposes of this investigation, the APP was defined as the plane defined by the most anteriorly prominent aspect of the two ASISs and the most prominent anterior portion of the symphysis pubis.…”

“…Numerous reports suggest the ranges of accuracy with which implants can be placed using computer-assisted surgical navigation typically will have standard deviations of 1°to 10°from the control [5,17,19,23,30,31,43,44,48]. We believe the primary objective of computer-assisted surgery (CAS) is to eliminate unacceptable outliers and we discuss limitations of these prior studies.…”