Technology and hip arthroplasty: acquiring skills and improving outcomes
Creators: name: Logishetty, Kartik
Publisher: name: Imperial College London
Year: 2020

description: The goals of modern total hip arthroplasty (THA) are an early return to activity with maximal stability and no functional limitations. Several surgical approaches have been developed to provide access to the hip joint to perform THA; compared to the posterior approach (PA), the anterior approach (AA) is purported to reduce the risk of dislocation and enable early return to function. The steep learning curve of this approach is well-described, so methods are required to enable surgeons to consistently deliver precise surgery without complications. The broad aims of this thesis were to 1) determine if the anterior approach hip arthroplasty confers a biomechanical advantage, and 2) identify novel technologies to improve the training and performance of this procedure. A cadaveric study assessed the stable range of motion conferred after conventional THA, dual- mobility total hip arthroplasty (DM-THA) and hip resurfacing arthroplasty (HRA), when performed through an anterior or posterior approach, before and after capsular repair. Of the twelve functional positions tested, conventional AA-THA with capsular closure dislocated in 0% while PA-THA dislocated in 17%. DM-THA and HRA did not dislocate with capsular closure, irrespective of approach. This study showed that the hip capsule is an important stabiliser in the early post-operative period. It functions as a wrapping leash around the prosthetic femoral head in flexion. The anterior approach and larger femoral implant sizes better preserve this function in positions of typical in vivo dislocation. While the attraction of AA hip arthroplasty was evident, cognitive task analysis (CTA) and the Delphi methodology was employed with an international group of expert hip surgeons to understand the technical steps, pitfalls, and steps to mitigate or address common complications. These data were also used to create a task-specific checklist (TSC) and to develop a cognitive training tool (CTT). Additionally, CTA data was used to create an immersive Virtual Reality (iVR) platform using information centric engineering (ICE) and agile development principles. CTA identified acetabular implant orientation as a critical, technical skill and a source of error for surgeons converting from PA to AA. An augmented reality (AR) software was thus designed and integrated with the Microsoft HololensTM headset to enable cup orientation to be tracked precisely to patient-specific targets on a drybone pelvis. The CTT was validated in an international multicentre RCT of 36 surgical trainees, comparing it to conventional training materials. CTT-trained surgeons performed simulated THA 35% more quickly with 69% fewer errors in instrument selection; required 92% fewer prompts; and were more accurate in cup orientation. The ability and feasibility of iVR training for AA-THA was ascertained in a 6-week curriculum of 32 surgical trainees. Their performance was compared to expert-derived benchmarks. Trainees progressively developed technical skills in iVR on a learning curve, on average plateauing after four sessions. Compared to baseline tests, their errors were reduced by 79%, assistive prompts by 70%, and procedural duration by 28%. A sawbone assessment demonstrated transfer of acetabular and femoral bone preparation skills between iVR and the real world. An RCT of 24 surgical trainees then compared a 6-week iVR program to conventional preparatory methods. The primary outcome measure was cadaveric AA-THA performance measured by two expert, blinded surgeons using a THA-specific Procedure Based Assessment. iVR-trained surgeons performed at a higher level than controls, on average completing AA-THA ‘with minimal guidance or intervention’. On average, surgeons required guidance for most or all the procedure. iVR-trained surgeons completed 80% more steps than controls, were 12° more accurate in cup orientation, and were 18% faster. Lastly, an RCT of 24 students compared AR headset-based training to coaching from a hip surgeon for learning acetabular cup orientation. It showed that AR was more accurate at providing guidance (1° vs. 6°error), and equivalent to the surgeon for delivering training to novices. However further improvements in hardware are needed before the AR prototype can be recommended for routine use, and AR may be more appropriate as an intra-operative navigation tool. It is concluded that the anterior approach for hip arthroplasty may confer greater immediate postoperative stability than the posterior approach, by preserving the function of the hip capsule, which may explain lower dislocation rates in retrospective clinical studies. However, cognitive task analysis showed that this approach is beset with unique technical surgical challenges, which reflect its well-reported complication profile. Training for AA-THA can be enhanced using cognitive training and immersive virtual reality, to shorten the learning curve and improve psychomotor skills. Future research should focus on ensuring that these technologies can be integrated into routine clinical training for the surgical team, and that they can deliver real clinical improvements.