Intraoperative Manufacturing of Patient-Specific Instrumentation for Shoulder Arthroplasty: A Novel Mechatronic Approach

Abstract

Optimal orthopaedic implant placement is a major contributing factor to the long term success of all common joint arthroplasty procedures. Devices such as three-dimensional (3D) printed, bespoke guides and orthopaedic robots are extensively described in the literature and have been shown to enhance prosthesis placement accuracy. These technologies, however, have significant drawbacks, such as logistical and temporal inefficiency, high cost, cumbersome nature and difficult theatre integration. A new technology for the rapid intraoperative production of patient-specific instrumentation, which overcomes many of the disadvantages of existing technologies, is presented here. The technology comprises a reusable table side machine, bespoke software and a disposable element comprising a region of standard geometry and a body of moldable material. Anatomical data from computed tomography (CT) scans of 10 human scapulae was collected and, in each case, the optimal glenoid guidewire position was digitally planned and recorded. The achieved accuracy compared to the pre-operative bespoke plan was measured in all glenoids, from both a conventional group and a guided group (GG). The technology was successfully able to intraoperatively produce sterile, patient-specific guides according to a pre-operative plan in 5min, with no additional manufacturing required prior to surgery. Additionally, the average guidewire placement accuracy was 1.58mm and 6.82∘ in the manual group, and 0.55mm and 1.76∘ in the guided group, also demonstrating a statistically significant improvement.