Evaluation of the Accuracy of Computed Tomography–Based Navigation for Femoral Stem Orientation and Leg Length Discrepancy

Evaluation of the accuracy of femoral component orientation by the CT-based fluoro-matched navigation system

“…The registration of the CT-based navigation system is achieved by matching the intraoperative surface shapes of the patient's anatomical landmarks with the preoperative CT data, whereas the registration of the CT-based fluoro-matched navigation system is achieved by matching the fluoroscopic image of the patient's anatomical landmarks with the preoperative CT data. Several studies have demonstrated that component orientation positioning is achieved more accurately using the CT-based navigation system rather than by using a CT-free navigation system [5,8,9]. In contrast, Kilties did not observe any significant differences between CT-based and CT-free navigation; however, both navigation systems reduced the variation in the component positioning compared with the conventional free-hand method [10].…”

“…However, they did not show the measurement error. Kitada et al [8], who also analysed the accuracy of CT-based navigation, reported that the average stem antetorsion of the navigation record was 31.1°± 11.7°and the postoperative measurement with CT data was 31.7°±11.7°; furthermore, they reported an average stem valgus in the navigation record of −0.1°±2.6°and a postoperative measurement with CT data of 0.1°±1.8°. These authors reported measurement errors to be−0.6°±4.8°for antetorsion and −0.2°±1.8°for valgus [8].…”

Effects of coordinate-system construction methods on postoperative computed tomography evaluation of implant orientation after total hip arthroplasty

“…Many investigators have evaluated the clinical accuracy (deviation of implant orientation from preoperative planning to postoperative measurement) and measurement error (deviation of orientation from intraoperative final measurement by navigation system to postoperative measurement) of navigation systems [18,21,[24][25][26][27][28]. Although a CT-based 3D templating technique is generally used for postoperative implant measurement, those results included errors in the evaluation methods, of course.…”

“…The CT-based threedimensional (3D) templating method using 3D preoperative planning software is generally recommended for evaluation of postoperative implant orientation from the point of view of reproducibility. [15][16][17][18][19][20][21] In this method, implant orientation to a bony (pelvic or femoral) coordinate system can be measured by overlaying a 3D computer-aided design (CAD) model of the implant on an image of the real implant on multiplanar reconstruction (MPR) CT images. Implantation accuracy is assessed by comparison of the preoperative planning orientation to the bony coordinate system.…”

Analysis of the Functional Outcome of Limb Length Discrepancy after Total Hip Replacement

“…[17,18] Limb length discrepancy[LLD] after total hip arthroplasty is important to optimize hip biomechanics and limb length discrepancy has Section: Orthopaedics several potential negative consequences for the patient, including Sciatica, chronic back pain, hip dislocation, the need for a shoe raise and a limp. [19,20] LLD most commonly involves overlengthening of the limb on the operative side because of a lengthening of the prosthetic headneck distance. [10] Although the prevalence of anatomical LLD after THA is high, [10] the impact of this leg length inequality on patient-reported functional outcome is unclear where as research has found that LLD has no effect on functional outcome but recent study found that patients with LLD reported a poorer functional outcome that those patients with equal leg lengths.…”