Accurate determination of post-operative 3D component positioning in total knee arthroplasty: the AURORA protocol

• Published in: Journal of orthopaedic surgery and research 2018-10, Vol.13 (1), p.275-275, Article 275
• Main Authors: Wakelin, Edgar A, Tran, Linda, Twiggs, Joshua G, Theodore, Willy, Roe, Justin P, Solomon, Michael I, Fritsch, Brett A, Miles, Brad P
• Format: Article
• Language: English
• Subjects: Accuracy; Alignment; Arthroplasty (knee); Arthroplasty, Replacement, Knee; Clinical outcomes; Computed tomography; CT scan; Humans; Imaging, Three-Dimensional; Joint surgery; Kinematics; Knee; Knee Joint - diagnostic imaging; Measurement techniques; Medical imaging; Methods; Orthopedics; Patient-Specific Modeling; Patients; Prostheses; Radiation Dosage; Registration; Reliability; Reproducibility; Reproducibility of Results; Systematic review; Tomography, X-Ray Computed; Total knee arthroplasty; X-rays
• ISSN: 1749-799X; 1749-799X
• DOI: 10.1186/s13018-018-0957-0

Successful component alignment is a major metric of success in total knee arthroplasty. Component translational placement, however, is less well reported despite being shown to affect patient outcomes. CT scans and planar X-rays are routinely used to report alignment but do not report measurements as precisely or accurately as modern navigation systems can deliver, or with reference to the pre-operative anatomy. A method is presented here that utilises a CT scan obtained for pre-operative planning and a post-operative CT scan for analysis to recreate a computation model of the knee with patient-specific axes. This model is then used to determine the post-operative component position in 3D space. Two subjects were investigated for reproducibility producing 12 sets of results. The maximum error using this technique was 0.9° ± 0.6° in rotation and 0.5 mm ± 0.3 mm in translation. Eleven subjects were investigated for reliability producing 22 sets of results. The intra-class correlation coefficient for each of the three axes of rotation and three primary resection planes was > 0.93 indicating excellent reliability. Routine use of this analysis will allow surgeons and engineers to better understand the effect of component alignment as well as the placement on outcome.