Novel robotic technology for the rapid intraoperative manufacture of patient-specific instrumentation allowing for improved glenoid component accuracy in shoulder arthroplasty: a cadaveric study.

BACKGROUND: Accurate prosthesis placement in arthroplasty is an important factor in the long-term success of these interventions. Many types of guidance technology have been described to date often suffering from high costs, complex theater integration, time inefficiency, and problems with day-to-day usability. We present a novel, intraoperative robotics platform, capable of rapid, real-time manufacture of low-cost patient-specific guides while overcoming many of the issues with existing approaches. METHODS: A prototype robotics platform was assessed in a 24-specimen cadaveric trial during sequential simulated shoulder arthroplasty procedures. The platform consisted of a tableside robot with sterile drapes and sterile disposable components. The robot itself comprised a 3D optical scanner, a 3-axis sterile robotic drill, and a 2-axis receptacle into which the disposable consumables were inserted. The consumable was composed of a region of rapidly setting moldable material and a clip allowing it to be reversibly attached to the robot. Computed tomographic (CT) imaging was obtained for all cadaveric specimens, and a surgical plan was created focusing on glenoid component position-specifically, guidewire position to allow for accurate glenoid preparation before implant insertion. Intraoperatively, for every specimen, the relevant osseous anatomy was exposed and humeral and glenoid preparation undertaken in the usual manner. The sterile disposable was used to create a mold of the joint surface. Once set, the mold was inserted into the robot and an optical scan of the surface was undertaken followed by automatic surface registration with the CT data and surgical plan. An automatic guide hole was subsequently drilled into the molded blank, which was removed from the robot and placed back into the patient, with the melded surface ensuring exact replacement. The guidewire was then driven through the guide hole in accordance with the preoperative plan. RESULTS: The novel robotic platform achieved average angular accuracies of 1.9° (standard deviation [SD] 1.3) version and 1.2° (SD 0.7) inclination with positional accuracy of 1.1 mm (SD 0.7) compared to a preoperative plan. DISCUSSION: We have described a novel robotics platform that is able to reliably produce patient-specific intraoperative guides to allow for accurate guidewire placement. Guidance is provided using a portable intraoperative device. The results suggest achieved accuracy levels may be equivalent to those seen in other existing guidance technologies; however, eventual in vivo trials and analysis is required. This technology has potential transferability to improve accuracy in other areas of arthroplasty.

Pelvic Protection Limiting Lower Limb Flail Reduces Mortality.

Pelvic blast injury is one of the most severe patterns of injury to be sustained by casualties of explosions. We have previously identified the mechanism of injury in a shock tube-mediated murine model, linking outward flail of the lower limbs to unstable pelvic fractures and vascular injury. As current military pelvic protection does not protect against lower limb flail, in this study we have utilized the same murine model to investigate the potential of novel pelvic protection to reduce injury severity. Fifty cadaveric mice underwent shock-tube blast testing and subsequent injury analysis. Pelvic protection limiting lower limb flail resulted in a reduction of pelvic fracture incidence from both front-on (relative risk (RR) 0.5, 95% confidence intervals (CIs) 0.3-0.9, p < 0.01) and under-body (RR 0.3, 95% CI 0.1-0.8 p < 0.01) blast, with elimination of vascular injury in both groups (p < 0.001). In contrast, pelvic protection, which did not limit flail, had no effect on fracture incidence compared to the control group and was only associated with a minimal reduction in vascular injury (RR 0.6, 95% CI 0.4-1.0, p < 0.05). This study has utilized a novel strategy to provide proof of concept for the use of pelvic protection, which limits limb flail to mitigate the effects of pelvic blast injury.

Three-dimensional printing in surgery: a review of current surgical applications.

BACKGROUND: Three-dimensional printing (3DP) is gaining increasing recognition as a technique that will transform the landscape of surgical practice. It allows for the rapid conversion of anatomic images into physical objects, which are being used across a variety of surgical specialties. It has been unclear which groups are leading the way in coming up with novel ways of using the technology and what specifically the technology is being used for. The aim of this article was to review the current applications of 3DP in modern surgical practice. MATERIALS AND METHODS: An electronic search was carried out in MEDLINE, EMBASE, and PsycINFO for terms related to 3DP. These were then screened for relevance and practical applications of the technology in surgery. RESULTS: Four hundred eighty-eight articles were initially found, and these were eventually narrowed down to 93 full-text articles. It was determined that there were three main areas in which the technology is being used to print: (1) anatomic models, (2) surgical instruments, and (3) implants and prostheses. CONCLUSIONS: Different specialties are at different stages in the use of the technology. The costs involved with implementing the technology and time taken for printing are important factors to consider before widespread use. For the foreseeable future, this is an exciting and interesting technology with the capacity to radically change health care and revolutionize modern surgery.

Mechanotransduction in osteogenesis.

Bone is one of the most highly adaptive tissues in the body, possessing the capability to alter its morphology and function in response to stimuli in its surrounding environment. The ability of bone to sense and convert external mechanical stimuli into a biochemical response, which ultimately alters the phenotype and function of the cell, is described as mechanotransduction. This review aims to describe the fundamental physiology and biomechanisms that occur to induce osteogenic adaptation of a cell following application of a physical stimulus. Considerable developments have been made in recent years in our understanding of how cells orchestrate this complex interplay of processes, and have become the focus of research in osteogenesis. We will discuss current areas of preclinical and clinical research exploring the harnessing of mechanotransductive properties of cells and applying them therapeutically, both in the context of fracture healing and de novo bone formation in situations such as nonunion. Cite this article: Bone Joint Res 2019;9(1):1-14.

The reverse zygomatic implant: a new implant for maxillofacial reconstruction.

This case report describes the rehabilitation of a patient who had been treated with a hemimaxillectomy, reconstruction with a latissimus dorsi vascularized free flap, and radiotherapy for carcinoma of the sinus some years previously. Limited jaw opening, difficult access through the flap to the bony site, and the very small amount of bone available in which to anchor the implant inspired the development and use of a new "reverse zygomatic" implant. For this treatment, site preparation and implant insertion were accomplished using an extraoral approach. The implant was used along with two other conventional zygomatic implants to provide support for a milled titanium bar and overdenture to rehabilitate the maxilla. Two years later, the patient continues to enjoy a healthy reconstruction. The reverse zygomatic implant appears to show promise as a useful addition to the implant armamentarium for the treatment of the patient undergoing maxillectomy.

Re-thinking 3D printing: A novel approach to guided facial contouring.

Rapid prototyped or three dimensional printed (3D printed) patient specific guides are of great use in many craniofacial and maxillofacial procedures and are extensively described in the literature. These guides are relatively easy to produce and cost effective. However existing designs are limited in that they are unable to be used in procedures requiring the 3D contouring of patient tissues. This paper presents a novel design and approach for the use of three dimensional printing in the production of a patient specific guide capable of fully guiding intraoperative 3D tissue contouring based on a pre-operative plan. We present a case where the technique was used on a patient suffering from an extensive osseous tumour as a result of fibrous dysplasia with encouraging results.