Moulding the Future of Patient Specific Instrumentation – the Shape of Things to Come

FOR BONE AND JOINT JOURNAL (BJJ) MOULDING THE FURTURE OF PATIENT SPECIFIC INSTRUMENTATION – THESHAPE OF THINGS TO COME Alastair Darwood1, Robin Richards2, Peter Reilly3, Roger Emery4, Ferdinando Rodriguez yBaena5 1. Prometheus Surgical ltd., London, United Kingdom2. Cavendish Implants, London, United Kingdom3. Imperial College NHS Trust, London, United Kingdom4. Imperial College, London, United Kingdom5. Imperial College, London, United Kingdom Alastair Darwood: Prometheus Surgical, 45 Wimpole st, London, UK, W1G 8SB Introduction: Optimal orthopaedic implant placement is a major contributing factor to the long term success ofall common joint arthroplasty procedures. Devices such as 3D printed bespoke guides and orthopaedic robotsare extensively described in the literature and have been shown to enhance prosthesis placement accuracy.These technologies have significant drawbacks such as logistical and temporal inefficiency, high cost,cumbersome nature and difficult theatre integration. A radically new disruptive technology for the rapidintraoperative production of patient specific instrumentation that obviates all disadvantages of currenttechnologies is presented. Method: An ex-vivo validation and accuracy study was carried out using the example of placing the glenoidcomponent in a shoulder arthroplasty procedure. The technology comprises a re-usable table side machine, bespoke software and a disposable elementcomprising a region of standard geometry and a body of mouldable material. Anatomical data from 10 human scapulae CT scans was collected and in each case the optimal glenoidguidewire position was digitally planned and recorded. The glenoids were isolated and concurrently 3D printed. In our control group, guide wires were manuallyinserted into 1 of each pair of unique glenoid models according to a surgeon’s interpretation of the optimalposition from the anatomy. The same surgeon used the guidance system and associated method to insert a guidewire into the second glenoid model of the pair. Achieved accuracy compared to the pre-operative bespoke plan was measured in all glenoids in both theconventional group and the guided group. Results: The technology was successfully able to intraoperatively produce sterile, patient specific guidesaccording to a pre-operative plan in 5 minutes including device set up and planning, at a minimal cost. In themanual insertion group, average accuracy achieved was 6.8o and 1.58mm with respect to the plan compared tothe guided group where an average of 0.74mm and 1.72 o was achieved.