As computer navigated surgery continues to progress to the forefront of orthopedic care, the application of a navigated total shoulder arthroplasty has yet to appear. However, the accuracy of these systems is debated, as well as the dilemma of placing an accurate tool in an inaccurate hand. Often times a system's accuracy is claimed or validated based on postoperative imaging, but the true positioning is difficult to verify. In this study, a navigation system was used to preoperatively plan, guide, and implant surrogate shoulder glenoid implants and fiducials in nine cadaveric shoulders. A novel method to validate the position of these implants and accuracy of the system was performed using pre and post operative high resolution CT scans, in conjunction with barium sulfate impregnated PEEK surrogate implants. Nine cadaveric shoulders were CT scanned with .5mm slice thickness, and the digital models were incorporated into a preoperative planning software. Five orthopedic shoulder specialists used this software to virtually place aTSA and rTSA glenoid components in two cadavers each (one cadaver was omitted due to incomplete implantation), positioning the components as they best deemed fit. Using a navigation system, each surgeon registered the native cadaveric bone to each respective CT. Each surgeon then used the navigation system to guide him or her through the total shoulder replacement, and implant the barium sulfate impregnated PEEK surrogate implants. Four cylindrical PEEK fiducials were also implanted in each scapula to help triangulate the position of the surrogate implants. Previous efforts were attempted with stainless steel alloy fiducials, but position and image accuracy were limited by CT artifact. BaSO4 PEEK provided the highest resolution on a postoperative CT with as little artifact as possible. All PEEK fiducials and surrogate implants were registered by probing points and planes with the navigation system to capture the digital position. A high resolution post operative CT scan of each specimen was obtained, and variance between the executed surgical plan and PEEK fiducials was calculated.INTRODUCTION
METHODS
Outcome measures are an essential element of our industry: comparing a novel procedure against an established one requires a reliable set of metrics that are comprehensible to both the technologist and the layman. We surmised that a detailed assessment of function before and after knee arthroplasty, combined with a detailed set of personal goals would enable us to test the hypothesis that less invasive joint and ligament preserving operations could be demonstrated to be more successful, and cost effective. We asked the simple question: how well can people walk following arthroplasty, and can we measure this? Using a treadmill, instrumented with force plates, we developed a regime of walking at increasing speeds and on varying inclines, both up and down hill. The data from the force plates was then extracted directly, without using the proprietary software that filtered it. Code was written in matlab script to ensure that missed steps were not mistakenly attributed to the wrong leg, automatically downloading of all the gait data at all speeds and inclines. The pattern of gait of both legs could then be compared over a range of activities. Wide variation is seen in gait both before and after arthroplasty. The variables that are easiest to explain are these:
width of gait – this appears to be a pre-morbid variable, not easily correctible with surgery. (figure 1) top walking speed – total knee replacement is associated with 11% lower top speeds than uni knees or normals (p < 0.05) change in stride length with increasing speed: normal people increase their walking speed by increasing both their cadence and their stride length incrementally until a top stride length is reached. Patients with a total knee replacement do not increase their stride length at a normal rate, having to rely on increasing cadence to deliver speed increase. Patients with uni or bi-compartmental knee replacements increase speed like normal people. Downhill gait: as many as 40% of fit patients with ‘well functioning’ total knee replacements choose not to walk downhill at all, while all fit patients with ‘well functioning’ partial replacements are able to do this. Those who can manage, can only manage 90% of the normal speed, unlike unis which are indistinguishable from normal (p < 0.05)Materials and methods
Results
Barriers to the adoption of unicompartmental knee arthroplasty (UKA) by new consultants could be explained by its higher revision rate, to which mal-positioned components contribute. The aim of this study was to determine whether robotic technology enables inexperienced surgeons to perform accurate UKAs when compared to current conventional methods After randomisation, sixteen trainees who had never performed UKAs performed three medial UKAs (Corin Uniglide), one per week, on dry-bone simulators by either robotic (Sculptor RGA) or conventional methods. They were instructed to match a universal 3D-CT based pre-operative plan that would result from a UKA based on the conventional jigs and operating guide. The knees were laser scanned and software used to compare the planned and actual implant positions. Feedback was given to trainees between attempts. Translational and rotational positioning errors were measured in all six degrees of freedom for both components At all attempts robotic medial UKAs were more accurate in both translational and rotational alignments for both components reaching statistical significance (p<0.005) at all attempts for rotational errors. Considering outliers, the maximum rotational errors of the robot group was 9° and 7° for the tibial and femoral components respectively. For the conventional group this reached 18° and 16° for the tibial and femoral components respectively Robotic technology allows inexperienced surgeons to perform medial UKAs on dry bone models with acceptable accuracy and precision on their first attempt. Conventional jigs do not. The adoption of robotic technology might provide new consultants with the confidence to offer UKAs to their patients by limiting the inaccuracies inherent in conventional equipment.
The introduction of the Stanmore Implants Savile Row mobile-bearing UKA procedure in July 2011 marked a world first – the use of a patient-specific knee implanted with robotic technology – the Sculptor Robotic Guidance Arm (RGA). This union gives a truly personalised solution by designing an implant for each patient based upon preoperative CT data and using Sculptor RGA to prepare the bone accurately so that the implant is correctly positioned as planned. The purpose of this study is to evaluate the accuracy of Sculptor RGA both in-vitro and in-vivo. We report on the accuracy of our first clinical procedures. In-vitro: CTs of plastic-bones were used to create plans for Sculptor RGA, establishing a relationship between the implant position and plastic-bone (planned-transform). Sculptor RGA was then used to prepare bones for 16 UKA implants mimicking the clinical set-up. The implants were placed in the prepared bones without cement. A coordinate-measuring-arm was used to register a)the bone, and b)the implant in relation to the bone (achieved-transform). The difference between planned-and-achieved transforms gives the error in implant position. In-vivo: Preoperative CTs of 8 OA patients, acquired using the low-dose Imperial Knee CT protocol, were used to plan the position and the shape of the patient-specific implants. Intra-operatively, Sculptor RGA was used to register and prepare the bone and the implants were cemented in place. Post-operative CTs were also acquired. Two techniques were used to measure planned-to-achieved positions of the implants: 1). Preoperative-to-postoperative CT image registration followed by extraction of the achieved implant position and comparison with the plan, 2). Surface-to-surface registration of bone-models segmented from the preoperative and postoperative CTs followed by extraction of the achieved implant position and comparison with the plan.Introduction
Methods
The combination of patient-specific “just-in-time” implant manufacture and robotic technology has not yet been reported. The robot enables accurate placement of anatomically-matched implants. It should be cost-effective, simplify the procedure, and reduce instrumentation. The aims of this study were to determine whether the procedure was safe, radiographically accurate, and comparable in time and cost to conventional arthroplasty. All patients over 3 months post-op were included. Component position, orientation and size were determined from CT scans by the surgeon prior to manufacture. The implants were inserted using the Sculptor robot, which is supplied free of cost (Savile Row, Stanmore Implants, UK). Following registration, bone was milled away using a high-speed burr under haptic control of the robot. The implants were cemented and a mobile bearing inserted. Patients were followed up clinically and radiographically. Oxford and EQ-5D scores were obtained. Costs of the implant, instruments, and consumables were calculated and compared to published data for conventional UKA and TKA.Background
Methods
Fractures to the distal radius are costly and debilitating injuries. While it is generally accepted that the leading cause of these injuries is a fall onto an outstretched arm, the mechanics of the injury are less well understood. The main limitations of past research are the use of unrealistic loading rates or uncontrolled loading protocols. Therefore, the purpose of this research was to examine the mechanical response of the distal radius pre-fracture and at fracture, under dynamic loads indicative of a forward fall. Eight cadaveric radius specimens were cleaned of all soft tissues and potted at a 75o angle (representative of the angle between the volar radius and the ground) up to the distal third of the radius. A custom designed pneumatic impact system was used to apply impulsive impacts to the specimen at increasing energy levels until failure occurred. The intra-articular surface of the radius rested against a model scaphoid and lunate made from high density polyethylene (Sawbones) attached to a 5 degree of freedom load cell that in turn was attached to an impact plate. The position of the carpals within the intra-articular surface simulated 45o of wrist extension. Following failure (defined as the specimen being fractured into at least 2 distinct pieces), the specimens were removed from the testing apparatus and the location, type, pattern and severity of injury was noted and classified using the Frykman and Melone classification systems. Energy input and force variables were also collected at failure.Purpose
Method
The Oxford Knee Score is a well validated, commonly used scoring system. Previous studies have suggested that the score is influenced by demographic differences between patients in particular the functional component more than the pain and clinical components. The aim of this study was to further assess this using a large number of patients. The pre, 3 months and 12 months post-surgical Oxford Knee Scores were collected from 1492 patients from five distinct demographic locations undergoing total knee arthroplasty over twelve years under the care of 8 different consultants. A total of 735 patients had complete data sets. The scores were than analysed to test whether age, postcode, sex or consultant in charge had any significant effects on the outcome.Introduction
Methods
Paediatric tibial fractures, unlike femoral fractures do not have much potential for overgrowth. In simple factures of the tibial shaft treated non-operatively the major problems are shortening and malunion. In complex injuries with extensive soft tissue disruption and bone loss, the long-term aim of reconstruction is to achieve union with a fully functional limb without limb-length inequality. Four children (Age range 6-12 years) who sustained high-energy grade III open fractures of the tibia were treated with acute shortening and bone transport. Any soft tissue reconstructive and secondary grafting procedures for delayed union were recorded. The children were prospectively followed up to fracture union. Distraction ostegenesis proceeded until limb length equality was achieved and the regenerate allowed to consolidate.Introduction
Methods
On 7 July 2005, four bombs were detonated on the London transport system. Three of these bombs exploded almost simultaneously at 08:50h affecting the underground tube network at Aldgate, King's Cross and Edgware Road stations. The fourth bomb exploded at 09:47h on a double-decker bus in Tavistock Square. There were 54 deaths in total at the scenes and over 700 injured. 194 patients were brought to the Royal London Hospital. 167 were assessed in a designated minor injuries unit and discharged on the same day. 27 patients were admitted of whom 7 required ITU care, 1 died in theatre and 1 died post-operatively. The median Injurity Severity Score (ISS) in this group of patients was 6 (range 0-48) and the mean ISS was 12. The general pattern of injury in the critically ill patients was of mangled lower limbs and multiple, severely contaminated fragment wounds. Hepatitis B prophylaxis was administered to those patients with wounds contaminated by foreign biological material. 11 primary limb amputations were performed in 7 patients. 9 limb fasciotomies, 5 laparotomies and 1 sternotomy were carried out. 3 patients had blast lung injury. All patients who underwent primary amputations and debridement received further regular inspections in theatre. These inspections formed the majority of our theatre work. Under no circumstance was initial reconstructive surgery attempted. Delayed primary closure and split skin grafting of all wounds was completed by the end of the second week. There have been no sepsis-related deaths. Our experience at The Royal London has allowed us to revisit the principles of blast wound management in a peacetime setting. A number of lessons were learned regarding communication and resource allocation. A multi-disciplinary approach with the successful execution of a major incident plan is the key to managing an event of this magnitude.
