The variables involved in a robotic THA can exceed 52: many parameters as pelvic orientation with CT scan, templating, offset, and leg-length, acetabular reaming, femoral osteotomy, mapping the anatomy; predefining safe zones, robotic execution, femoral head size, thickness of PE etc. with several variables for each parameter, with a total number of variables exceeding 52. This familiar number is the number of cards in a standard deck. The number of possible combinations (factorial 52! = 10^67) to shuffle the cards (and may be to perform a THA) is greater than the number of atoms on earth! Thinking that artificial intelligence and robotics can solve these problems, some surgeons and implant manufacturers have turned to artificial intelligence and robotics. We asked two questions:1) can robot with artificial intelligence really process 52 variables that represent 10^67 combinations? 2) the safety of the technology was ascertained by interrogating Food and Drug Administration (FDA) database about software-related recalls in computer-assisted and robotic arthroplasty [1], between 2017 and 2022. 1). The best computers can only calculate around 100 thousand billion combinations (10^14), and with difficulty: it takes more than 100 days to arrive at this number of digits (10^14) after the decimal point for the number π (pi). We can, therefore, expect the robot to be imperfect. 2). For the FDA software-related recalls, 4634 units were involved. The FDA determined root causes were: software design (66.6%), design change (22.2%), manufacturing deployment (5.6%), design manufacturing process (5.6%). Among the manufacturers’ reasons for recalls, a specific error was declared in 88.9%. a coding error in 43.8%. 94.4% software-related recalls were classified as class 2. Return of the device was the main action taken by firms (44.4%), followed by software update (38.9%). 3). In the same period, no robot complained about its surgeon!. Hip surgeon is as intelligent as a robot and almost twice as safe

Introduction. Neither a surgeon's intraoperative impression or computer navigation parameters have been shown to be predictive of postoperative outcomes following TKA. The purpose of this study is to determine 1) whether a surgeon and a robot can predict the 1-year KOOS pain score (KPS) and 2) determine what factors correlate with poor KOOS scores in well aligned and balanced TKA. Methods. The data of 131 consecutive patients enrolled in a prospective trial was reviewed. All TKAs were performed using a dynamic ligament tensioning robotic system with a tibial first resection technique and a cruciate sacrificing ultracongruent knee implant. Each TKA was graded based on the final recorded mediolateral ligament balance at 10° and 90°: A) <1mm with an implanted insert thickness equal to planned (n=74); B) <1mm (n=25); C) <2mm (n=26); D) >2mm (n=6) (Table-1). The 1-year KPS for each knee grade were compared and the likelihood of achieving an KPS > 90 was calculated. Finally, the factors associated with lower KPS despite achieving a high grade TKA (A/B) was performed. The Mann-Whitney U test and Chi-squared analysis was performed. Results. Patients with a grade of A and B had higher 1-year KPS compared to knees rated C and D (p=0.031) (Fig-1). There was no difference in KPS in TKAs rated A or B, but 33% in this group did not report a KPS > 90. While there was no correlation with age, sex, preoperative deformity, and preoperative KOOS and PROMIS physical scores, patients with KPS < 90 despite a TKA rated A or B had lower PROMIS metal health scores compared to patients reporting KPS > 90 (54.1 vs. 50.8, p= 0.043). Finally, Grade A and B patients who scored KPS > 90 were more likely to respond with “my expectations were too low”, and they are performing better than expected compared to Grade A and B patients who scored KPS < 90 (40% vs 22%, p = 0.004). Summary. A robotic balanced knee is correlated with higher KPS at 1 year but not predictive. Despite accurate alignment, rotation, and ligament balance information, a robotic system could not guarantee excellent pain relief. Patient expectations and mental status also significantly affect the perceived success of TKA. For any figures or tables, please contact the authors directly

The discussion of outpatient unicompartmental knee arthroplasty (UKA) requires proof that it can be done safely and effectively, and also begs the question of whether it can be performed in an ambulatory surgery center (ASC) rather than a general hospital (which raises costs and is typically less efficient). Successful outpatient UKA requires carefully crafted algorithms/protocols, home support, preoperative planning and preparation, expectation management, risk stratification (not everyone is a candidate), perioperative pain management and buy-in from patients, support networks and the health care team. Relatively little data is available on the feasibility, safety and potential cost savings associated with this shift in care. We evaluated the costs and short term outcomes and complications of 150 consecutive UKAs performed in an ASC compared to those done in a general hospital both on an inpatient and outpatient basis. Determination of the setting of the outpatient surgery was made based on geographic preference by the patients; otherwise choice of inpatient or outpatient surgery in the hospital was left to the discretion of the surgeon and was primarily based on the patients' comorbidity profile and circumstances of home help. Total direct facility costs were calculated, including institutional supplies and services, anesthesia services, implants, additional PACU medications and services required, and costs associated with operating room use. Only total cost was evaluated, as it is the most consistent cost variable amongst the two institutions evaluated. The mean total direct cost of UKA in a general community hospital with an overnight stay was 1.24 and 1.65 times greater than the cost of UKA performed at the same hospital or an ASC on an outpatient basis, respectively. The mean total direct cost of outpatient UKA in a general hospital was 1.33 times greater than the mean total cost of UKA performed in an ASC. Semi-autonomous robotic technology has been introduced to optimise accuracy of implant positioning and soft tissue balance in UKA, with the expectation of resultant improvement in durability and implant survivorship. Currently, nearly 20% of UKA's in the U.S. are being performed with robotic assistance. It is anticipated that there will be substantial growth in market penetration over the next decade, projecting that nearly 37% of UKA's and 23% of TKA's will be performed with robotics in 10 years (Medical Device and Diagnostic Industry, March 5, 2015). First generation robotic technology improved substantially implant position compared to conventional methods; however, high capital costs, uncertainty regarding the value of advanced technologies, and the need for preoperative CT scans were barriers to broader adoption. Newer image-free robotic technology offers an alternative method for further optimizing implant positioning and soft tissue balance without the need for preoperative CT scans and with price points that make it suitable for use in an ASC. Currently, as a result of cost and other practical issues, <1% of first generation robotic technologies are being used in ASC's. Alternatively, more than 35% of second generation robotic systems are in use in ASC's for UKA, due to favorable pricing. In conclusion, UKA can be safely performed in the outpatient setting in select patients. Additionally, we demonstrated a substantial cost savings when UKA is performed in an outpatient setting and care is shifted from a general community hospital to an ASC. Finally, robotics can be utilised to optimise accuracy of implant placement and soft tissue balance in UKA, and newer image-free robotic technology is cost effective for outpatient UKA

In the framework of the modiCAS (Modular Interactive Computer Assisted Surgery) Project, which emerged from a collaboration of the University of Siegen and the University of Frankfurt in the fields of mechatronics and medicine, the development of a modular system to assist the surgeon during the whole planning and operation procedure has been started. A completely new realization of a planning system for bone surgery and alloarthroplasty is presented. Characteristics of the new system are generic interfaces for navigation, robotics and real-time data acquisition, graphic interactivity, documentation of each planning-step, a flexible wizard-guided concept and adaptable teaching modes. The system can be configured to any data source such as X-ray, CT, MRI, US with individual calibration. For planning, the data sources can be merged in any user defined way. In contrast to all existing planning systems the presented system can optionally be linked to navigation and robotic systems. The software was realized to run platform-independent on any personal computer surrounding. We used commercially available software libraries for computer graphics and graphical user interface programming. The whole system consists of several modules which are closely linked together and support all major pre- and intraoperative steps of surgery. The user interface remains the same during the planning and the intervention. Preoperative planning is carried out on a totally new planning station comprising an interactive and intuitive graphic interface, while intraoperative features include interactive matching procedures, true real-time-capability and incorporation of navigation and robotics. Initially we realized modules to support total hip allo-arthroplasty. The first application of the system is for a clinical trial on total hip alloarthroplasty. Planning is performed on the basis of radiographs and CT-datasets. Intraoperatively a navigation system and a robotic surgery system are used. Preliminary results show very precise and reproducible plannings that could be achieved in short time without special training of the clinician. Furthermore the unlimited intraoperative access to the whole planning dataset appeared to be very convenient to the surgeon because it allowed immediate response to unforeseen patient specific situations. Future adaptations of the universal planning system will be total knee alloarthroplasty, spine surgery and trauma surgery. The existing system can easily be configured to any surgical procedure because the same basic functionality is used for all applications and only special configurative datasets have to be generated for each application. The open architecture of the system enables easy integration of further input or output devices, an easy adaptation to different interventions, planning styles and operative techniques is possible

Introduction. We report 10-year clinical outcomes of a prospective randomised controlled study on uni-compartmental knee arthroplasty using an active constraint robot. Measuring the clinical impact of CAOS systems has generally been based around surrogate radiological measures with currently few long-term functional follow-up studies reported. We present 10 year clinical follow up results of robotic vs conventional surgery in UKA. Material and methods. The initial study took place in 2004 and included 28 patients, 13 in the robotic arm and 15 in the conventional arm. All patients underwent medial compartment UKA using the ‘OXFORD’ mobile bearing knee system. Clinical outcome at 10 years was scored using the WOMAC scoring system. Results. 13 patients were initially included in the robotic arm, of these one was revised following trauma and a further two patient died leaving at total of 10 with an average age of 80 years. In the control arm, out of a total of 15 patients, 3 were revised to a total knee replacement due to pain, 1 has died and 1 lost to follow-up. Their mean age is 81. A total of 19 patients were included (conventional n=9, robotic n=10) in this follow up study. The WOMAC scores for the robotic group were lower - (p<0.05). Discussion. There is a paucity of data on 10 year outcome of computer assisted UKA and whilst most studies show no clinical benefit, our study suggests a better outcome, however our numbers now are small (n=19). In our original study 1 the primary outcome measure, tibiofemoral alignment in the coronal plane was within 2 degrees of the planned position in the robotic group whilst in the conventional group only 6 of the 15 knees achieved this level of accuracy - Fig 1. The primary hypothesis was that the use of an active constraint robot improved prosthetic position. This accuracy continues to be associated with improved functional outcome. Three revisions were performed prior to this period and were considered technical failures and have been excluded from this analysis

Closed manipulation of long bone fractures is often a difficult problem. Muscles and soft tissues along with gravity, acting along the fracture fragments, can cause complex displacement and deformity at the fracture site. At the same time surgeons have to rely on human assistants to manipulate and realign these fractures. This depends a lot on their individual skills and furthermore human assistants are prone to fatigue and are liable to imprecise movements. A robotic device has precision, accuracy, and steadiness along with the ability to be programmed. The purpose of this study is to conceptualize a device, which can aid orthopaedic surgeons to manipulate long bone fractures. Extensive literature search was done using the Internet and conventional resources, to find recent developments in the use of robotics in trauma and fracture surgery. Different models of robots were considered and finally a parallel robot of the Stewart platform type was considered to be of the design that will be more compatible with an orthopaedic operating environment. Computer aided design and graphics modelling of the robot was done and range of motion and force it can generate was calculated. The prototype that was built had six degrees of freedom and enough force and range of motion to reduce and manipulate long bone fractures. The actual controlling interface of the robot through a PC was established. It is possible to build a robot for manipulating long bone fractures. Further research is being done to focus on the integration of the robot to fluoroscopic images and designing the correct attachment tools for the extremities

Introduction. Technology in Orthopaedic surgery has become more widespread in the past 20 years, with emerging evidence of its benefits in arthroplasty. Although patients are aware of benefits of conventional joint replacement, little is known on patients' knowledge of the prevalence, benefits or drawbacks of surgery involving navigation or robotic systems. Materials and methods. In an outpatient arthroplasty clinic, 100 consecutive patients were approached and given questionnaires to assess their knowledge of Navigation and Robotics in Orthopaedic surgery. Participation in the survey was voluntary. Results. 98 patients volunteered to participate in the survey, mean age 56.2 years (range 19–88; 52 female, 46 male). 40% of patients believed more than 30% of NHS Orthopaedic operations involved navigation or robotics; 80% believed this was the same level or less than the private sector. A third believed most of an operation could be performed independently by a robotic/navigation system. Amongst perceived benefits of navigation/robotic surgery was more accurate surgery(47%), quicker surgery (50%) and making the surgeon's job easier (52%). 69% believed navigation/robotics was more expensive and 20% believed it held no benefit against conventional surgery, with only 9% believing it led to longer surgery. Almost 50% would not mind at least some of their operation being performed with use of robotics/navigation, with a significantly greater proportion of these coming from patients aged under 50 years. Conclusions. Although few patients were familiar with this new technology, there appeared to be a strong consensus it was quicker and more accurate than conventional surgery. Many patients appear to believe navigation and robotics in Orthopaedic surgery is largely the preserve of the private sector. This study demonstrates public knowledge of such new technologies is limited and a need to inform patients of the relative merits and drawbacks of such surgery prior to their more widespread implementation

1. Role of enabling technologies in THA: Setting the stage. a. Impact of component position in THA. 1. Wear/lysis. Effect of edge loading, impingement. 2. Instability. Together, the most common cause for revision hip arthroplasty. b. Ideal component position:. 1. Work of Lewinneck: the “safe zone” for stability. c. Can we achieve this?. 1. HSS study. 2. Mass General Study: 2000 THR's, only 50% within desired range. d. Need for assistance? Maybe?. 2. Types of Guidance:. a. Navigation: use of mechano or optical tracking system that after some registration acquisition, facilitate spatial placement. The systems can either be image based (pre-operative CT scan) or imageless where multiple points are acquired and a “best fit” is matched to a library of pelvic geometries. b. Robotics: combines the spatial application of navigation with the precision bone preparation afforded by robotic milling. Robotic use can either be active whereby the robotic preparation is performed by the computer driven system (ie ROBODOC™). Alternatives include surgeon controlled but robot guided (haptic) type systems. 3. Perceived Advantages:. a. Robotic assisted: Bone preparation: spherical shape of socket consistently “rounder” than manually controlled reaming. Implant insertion: by establishing boundaries of insertion, final implant position achieves desired position. 4. Unknowns:. a. Cost effectiveness. b. Do we really know where the socket is best located for an individual patient?. While we rely on the safe zone of Lewinneck for our desired implant position, the impact of lumbosacral disease deformity could/should impact where the socket is placed

The Acrobot®, an active constraint “hands-on” robotic system, gives navigation cues to the surgeon, and also assists him in the surgery, using active software constraints if he tries to depart from the preoperative plan. It has just entered clinical trials. We report the first 5 cases. The Acrobot® system for precision total knee arthroplasty comprises the following components:. 1. A CT-based planning system. 2. The limb positioning system. 3. The Acrobot’s hardware components:. a gross positioning device with separate brakes and encoders, locked off for safety during the procedure,. a fully back-driveable low force robot, and. a force control handle on the robot close to the high-speed milling tool. 4. The Acrobot’s software which:. imports the preoperative plan,. allows anatomic registration. provides navigation,. physically assists the surgeon perform his plan. Each patient’s knee scores were monitored and postoperative CT scan was compared with the preoperative plan. Seven robot assisted arthroplasties have been performed. No significant complications have been encountered. The Knee and Womac Scores show that the procedure is safe and comparable to conventional surgery in the early postoperative period. The envelope of error on postoperative CT scans has been within the accuracy of the method of measurement, at < 1 mm and < 10 without the outliers which haunt every clinical series. The Acrobot® system for total knee arthroplasty has completed its preliminary trial satisfactorily. It provides a handson operation but with robotic levels of accuracy. It is suitable for conventional open surgery, but its real place will be in the arena of minimally invasive unicondylar knee arthroplasty, hip arthroplasty and resurfacing, and in the spine, where active constraint will prevent potentially dangerous surgical errors

The disadvantages of sawing for precise bone cuts are well known: untrue cuts, heat and metal wear. The main limiting factors of available milling devices are the difficult handling and high costs, especially if the devices are based on a robot. Supported by clinical users and mechanical engineers a milling concept adopted from machining has been realised in order to overcome this limitations. The „All-in-One Milling-Tool“ achieves the same precision of a robot by a mechanically guided milling resection far below the necessary investment for a robot. Three methods are provided for the alignment of the resection planes and will be discussed: intramedullary adjustment, 3D CT-based planning and intramedullar performance as well as the performance under control by navigation. All versions are based on a handheld resection and guarantee a visual and haptical feedback for the surgeon. The use of navigation has the advantage of the accurate transfer of the 3D plan into the OR, the interactive facilitated alignment und resection steps and the documentation of planned and actual implant position

The disadvantages of sawing for precise bone cuts are well known: untrue cuts, heat and metal wear. The main limiting factors of available milling devices are the difficult handling and high costs, especially if the devices are based on a robot. Supported by clinical users and mechanical engineers a milling concept adopted from industrial machining has been realised in order to overcome this limitations. The “All-in-One Milling-Tool” achieves the same precision of a robot by a mechanically guided milling resection far below the necessary investment for a robot. Once fixed at the femur, the device allows all femural and tibial resections. Three methods are provided for the alignment of the resection planes and will be discussed: intramedullary adjustment, 3D CT-based planning and intramedullar performance as well as the performance under navigation control. All versions are based on a handheld resection and guarantee a visual and haptical feedback for the surgeon. The use of navigation has the advantage of the accurate transfer of the 3D plan into the OR, the interactive guided and facilitated alignment und resection steps and the documentation of planned and actual implant position

ROBODOC is a well known tool for a computer assisted arthroplasty. However, the incision tends to enlarge with the system because of the restriction of range of motion. We have developed the robot system for minimally invasive arthroplasty. This report shows the accuracy of our system composed of original planning software, navigation and bone cutting robot. We took the DICOM data of cadaver knees from computed tomography. The data were transferred to the workstation for planning. Matching points for registration and cutting planes were determined on the planning software. Cutting tool was the 6th robot which was able to recognize the locations of its apex and the cadaver knee with navigation system. We made five planes for TKA and two planes for UKA on femur. Then we made one plane on tibia. We evaluated the accuracy by measurement the location of cutting plane under navigation system and by CT data. The registration errors of femur and tibia were less than 1.0mm about cadaver knees. The errors of cutting planes were 1.3 mm about the distal end of femur and 0.5 mm about the proximal end of tibia. The accuracies of the angles of cutting planes were 1.9 degrees and 0.8 degrees compared to the mechanical axis. The errors of anterior and posterior plane of femur were increased compared to the distal plane. It was because the accuracy of registration were correct in axial direction but was not satisfied in rotational direction. The error was considered by the location of points which decided the rotation alignment. We will make effort to minimize the errors of registration and put it into practical use as soon as possible

Introduction. Total-knee-arthroplasty (TKA) is used to restore knee function and is a well-established treatment of osteoarthritis. Along with the widely used fixed bearing TKA design, some surgeons opt to use mobile bearing designs. The mobile-bearing TKA is believed to allow for more freedom in placement of the tibial plate, greater range of motion in internal-external (IE) rotation and greater constraint through the articular surface. This current study evaluates 1) the kinematics of a high constraint three condyle mobile bearing TKA, 2) the insert rotation relative to the tibia, and 3) compares them with the intact knee joint kinematics during laxity tests and activities-of-daily-living (lunge, level walking, stairs down). We hypothesize that 1) in contrast to the intact state the anterior-posterior (AP) stability of the implanted joint increases when increasing compression level while 2) maintaining the IE mobility, and that 3) the high constraint does not prevent differential femorotibial rollback during lunge. Methods. Six fresh-frozen human cadaveric knee joints with a mean donor age of 64.5 (±2.4) years and BMI of 23.3 (±7.3) were tested on a robot (KR140, KUKA) in two different states: 1) intact, 2) after implantation of a three condyle mobile bearing TKA. The tibia plateau and the insert of each tested specimen were equipped with a sensor to measure the insert rotation during testing. Laxity tests were done at extension and under flexion (15°, 30°, 45°, 60° 90°, 120°) by applying subsequent forces in AP and medial-lateral (ML) of ±100N and moments in IE and varus-valgus (VV) rotation (6Nm/4Nm, 12 Nm/-). Testing was performed under low (44N) and weight bearing compression (500N). Loading during the lunge, level walking and stairs descent activity was based on in-vivo data. Resulting data was averaged and compared with the kinematics of the intact knee. Results. Increasing the joint compression resulted in a 90% reduced AP laxity (increased stability) for the implanted case while the intact knee laxity stayed similar. In high compression the implanted IE mobility was reduced by 45% for low and mid flexion angles and by 20% for high flexion angles, while the intact knee IE mobility was reduced by 30% at low and mid flexion and 20% at high flexion. The trend of the rollback behaviour was similar for the implanted and intact joints and showed higher lateral than medial rollback (Figure 3 A). The average insert-rotation was highest during level walking (+ 5° to −2.5°) and lowest during lunge (−3.5° to 2.5° over flexion). Conclusion. The established hypotheses were supported by the above listed results. Increasing the joint compression in the mobile bearing design stabilized the knee in the AP direction and maintained the IE mobility similar to the intact knee. This can be directly related to the design of the TKA articular surface, which has a high impact on constraint as soon as the joint is loaded. However, the high constraint of the TKA did not prevent differential rollback

Aims: We compared the primary rotatory stability of robot implanted hip endoprostheses with manually implanted stems. We examined three different types of prosthesisstems: Osteolock, CBC, Excia. Methods: 10 stems of each prosthesis type were implanted in identical polyurethan foam blocks: 5 manually, 5 robot assisted (CASPAR-System). The forces, which were necessary for the implantation of the stem were documented digitally. Now a deþnated rotatory stress was put on the stem with a torquing machine. The torsional moment was also documented digitally. Results: The strengthway- diagram of the implantation in robot assisted reamed foam blocks was homogeneous at each type of prosthesis. At the manually reamed blocks, the diagrams were very inhomogeneous. The rotatory test showed also very unitary results at the robot implanted stems with only minimal variations of the results from the median. The range of results after manually implantation was much higher. In all types of protheses the use of the robot system lead to a signiþcantly higher rotatory stability. CBC stem is signiþcantly most stable for rotatory forces after robot assisted implantation compared to the other two types. After manual implantation there was no differrent stability between the CBC and the Osteolock stem. The Excia stem showed the signiþcantly lowers rotatory stability after manual and robot assisted implantation. Conclusions: With a robot system the primary rotatory stabilty of hip endoprosthesis is improved indenpendtly of the type of the prosthesis. The inßuence of the stem design is also important for the rotatory stability, too

INTRODUCTION. Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients who have isolated osteoarthritis as a minimally invasive procedure. However, limited visualization of the surgical site provides challenges in ensuring accurate alignment and placement of the prosthesis. With robot-assisted surgery, correct implant positioning and ligament balancing are obtainable with increased accuracy. To date, there has not been a large series reported in the literature of UKAs performed with robotic assistance. The aim of this study was to examine the clinical outcomes of robot-assisted UKA patients. METHODS. 510 patients who underwent robotic-assisted UKA between July 2008 and June 2010 were identified (average age 63.7 years, range: 22 to 28 years). Clinical outcomes were evaluated using the Oxford Knee Score (OKS) and patients without recent follow-up were phoned. Revision rate and time to revision were also examined. RESULTS. Average length of stay was 1.4 days (range: 1 to 7 days). There was minimal blood loss with most procedures. There were two intra-operative complications, both in early patients in the series. The first intra-operative complication was broken alignment pins in both the femur and tibia. In the second complication, preparation was finished manually with a burr due to registration problems with the software. Both patients were doing well at most recent follow up and neither experienced further complications. At latest clinical follow-up, patients reported a mean OKS of 36.1 + 9.92. The revision rate was 2.5% with 13 patients either converted from an inlay to onlay prosthesis or conversion to TKA. The most common indication for revision was tibial component loosening, followed by progression of arthritis. One patient was revised due to infection. Mean time to revision was 9.55 + 5.48 months (range: 1 to 19 months). CONCLUSION. UKA with a robotic system provides good pain relief and functional outcomes at short-term follow-up. Ensuring correct component alignment and ligament balancing increases the probability of a favorable outcome. Proper patient selection for appropriate UKA candidates remains an important factor for successful outcomes. In combination with robotic assistance there can be a reduction in many of the failures seen with early systems

Objectives. Percutaneous iliosacral screw placement is a standard, stabilization technique for pelvic fractures. The purpose of this study was to assess the effectiveness of a novel biplanar robot navigation aiming system for percutaneous iliosacral screw placement in a human cadaver model. Methods. A novel biplanar robot navigation aiming system was used in 16 intact human cadaveric pelvises for percutaneous iliosacral screw insertion. The number of successful screw placements and mean time for this insertion and intra-operative fluoroscopy per screw-pair were recorded respectively to evaluate the procedure. The accuracy of the aiming process was evaluated by computed tomography. Results. Sixteen intact human cadaveric pelvises were treated with percutaneous bilateral iliosacral S1 screw placement (32 cannulated screws, diameter-7.3mm, Synthes, Switzerland). All screws were placed under fluoroscopy-guided control using the biplanar robot navigation aiming system (TINAV, GD2000, China). There was no failed targeting for screw-pair placements. Computed tomography revealed high accuracy of the insertion process. 32 iliosacral screws were inserted (mean operation time per screw-pair 56 ± 3 minutes, mean fluoroscopy time per screw-pair 11.7 ± 9 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely inserted in the cancellous bone (86%); II. secure positioning, but contacting cortical bone structures (9%); III. malplaced positioning, penetrating the cortical bone (5%). Conclusion. This cadaver study indicated that an aiming device–based biplanar robot navigation system is highly reliable and accurate. The promising results suggest that it has the advantages of high positioning accuracy, decreased radiation exposure, operational stability and safety. It can be used not only for the percutaneous iliosacral screw placement but also for other orthopedic surgeries that require precise positioning

A Prospective, randomised controlled trial demonstrates superior outcomes using an active constraint robot compared with conventional surgical technique in unicompartmental knee arthroplasty (UKA). Computer assistance should extinguish outliers in arthroplasty, with robotic systems being able to execute the preoperative plan with millimetre precision. We used the Acrobot system to deliver tailor made surgery for each individual patient. A total of 27 patients (28 knees) awaiting unicompartmental knee arthroplasty were randomly assigned to have the operation performed either with the assistance of the Acrobot or conventionally. CT scans were obtained with coarse slices through hips and ankles and fine slices through the knee joint. Preoperative 3D plans were made and transferred to the Acrobot system in theatre, or printed out as a conventional surgical aid. Accurate co-registration was confirmed, prior to the surfaces of the femur and tibia being milled. The outcome parameters included measurements of the American Knee Society (AKS) score and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index. These measurements were performed pre-operatively and at six, 18 weeks, and 18 months post-operatively. After 18 months two UKA out of the conventional trial (n =15) had been revised into a total knee replacement (TKA), whereas there were no revisions in the Acrobot trial group (n = 13). Using an active constrained robot to assist the surgeon was significantly more accurate than the conventional surgical technique. This study has shown a direct correlation between accuracy and improvement in knee scores at 6, 18 weeks and 18 months after surgery. At 18 months there continues to be a significant improvement in the knee scores with again a marked correlation between radiological accuracy and clinical outcome with higher accuracy leading to better function based on the WOMAC and American Knee Society Score

Introduction: Active Robots have been shown to be effective at performing arthroplasty, but some hesitation has been felt by the surgical world. The lack of human interface in the procedure has been one of the stumbling blocks towards wider acceptance. The Acrobot has been developed, at Imperial College London, in collaboration with University College London to allow the surgeon to perform the surgery himself, but with active constraint, preventing him from taking too much bone, or straying into soft tissue. Materials and methods: A preoperative planning system is used, based on ct data acquired without fiducial markers. Semi-automated segmentation is performed. The surgeon then performs the virtual surgery on the bones on screen, allowing precise sizing, and orientation. The safe field of activity is then defined, within which the surgeon is free. The patient is positioned on the operating table and immobilised. Anatomic registration is then performed, and when sufficient accuracy obtained, the milling procedure is begun. A high speed electric milling tool is used, and with it the bone planes are prepared sequentially. The prosthesis is then inserted in standard fashion. Results: Laboratory testing on dry bone and cadaveric models have confirmed that the registration process is now accurate. At the moment we are using a classical ICP algorithm to register the data points. For this test the Root Mean Square is 0.626 mm in a cadaveric model. This pinless anatomic registration can be achieved rapidly, if the initial siting points are accurately identified. Conclusion: The active constraint concept seems to be a safe and user friendly way of achieving robotic level accuracy with a human touch. Anatomic registration using the robot is accurate, and early clincal trials of total knee arthroplasty are encouraging

Introduction:. Acetabular component orientation has been linked to hip stability as well as bearing mechanics such as wear. Previous studies have demonstrated wide variations of cup placement in hip arthroplasty using conventional implantation techniques which rely upon either anatomic landmarks or the use of commercial positioning guides. Enabling technologies such as navigation have been used to improve precision and accuracy. Newer technologies such as robotic guidance have been postulated to further improve accuracy. The goal of our study was to evaluate the clinical reproducibility of a consecutive series of haptically guided THR. Methods:. 119 patients at 4 centers were enrolled. All patients had preoperative CT scans for the purpose of planning cup placement in lateral opening and version using proprietary software (Mako, Ft. Lauderdale, FL). All procedures were performed using a posterolateral approach. Following bone registration, acetabular preparation and component position is performed using haptic guidance. Final implant postion is ascertained by obtaining 5 points about the rim of the acetabular component and recorded. At 6 weeks, all patients had AP and cross-table lateral radiographs which were then analyzed for cup abduction and anteversion using the Hip Analysis Suite software. The goal was to determine the variability between desired preoperative plan, intraoperative measurement and postoperative results. Results:. Of the 119 hips replaced, 9 hips were excluded due to problems using the Hip Suite software leaving 110 hips for analysis. As seen in Table 1., the mean cup inclination was planned for 40.0 degrees. Intraoperative recorded inclination was 39.9 degrees and using the Martell software, 40.4 degrees. Planned cup anteversion was 18.7 degrees, with intraoperative measurement of 18.6 degrees and postoperative Hip Suite analysis 21.5 degrees. There was no significant difference between any of these measurements. Conclusion:. The use of a haptically guided robot to prepare and implant an acetabular component during total hip arthroplasty is both precise and accurate based upon this multicentered study. While further research determining optimal cup position is needed, these results suggest that the ability to achieve desired position is possible utilizing this enabling technology

Background. The acetabular labrum is an essential stabilizer of the hip joint, imparting its greatest effect in extreme joint positions where the femoral head is disposed to subluxation and dislocation. However, its stabilizing value has proved difficult to quantify. The objective of the present study was to assess the contribution of the entire acetabular labrum to mechanical joint stability. We introduce a novel “dislocation potential test” that utilizes a dynamic, cadaveric, robotic model that functions in real-time under load-control parameters to map the joint space for low-displacement determination of stability, and quantify using the “stability index”. Methods. Five fresh-frozen human cadaveric hips without labral tears were mounted to a six-degree-of-freedom robotic manipulator and studied in 2 distinct joint positions provocative for either anterior or posterior dislocation. Dislocation potential tests were run in 15° intervals, or sweep planes, about the face of the acetabulum. For each interval, a 100 N force vector was applied medially and swept laterally until dislocation occurred. Three-dimensional kinematic data from conditions with and without labrum were quantified using the stability index, which is the percentage of all directions a constant force can be applied within a given sweep plane while maintaining a stable joint. Results. Global stability indices, considering all sweep planes, were significantly greater with labrum intact than after total labrectomy for both anterior (Figure 1A) (p = 0.02) and posterior (Figure 1B) (p<0.001) provocative positions. Regional stability indices, based upon the expected range of dislocation for each provocative position, were also significantly greater and of slightly larger magnitude for the intact condition than after total labrectomy (p<0.001). Conclusions. This is the first known application of a six-degree-of-freedom robot to recreate mechanical hip impingement and dislocation to elucidate the role of the labrum in hip stability. Our results suggest that at least in extreme positions, the labrum imparts significant overall mechanical resistance to hip dislocation compared to the condition without the labrum. Regional contributions of the labrum are greatest in the direction of dislocation as foretold by joint position as indicated by region-based stability indices. Future studies involving more clinically relevant injury patterns with greater soft tissue preservation in a younger cadaveric population would better reflect the in vivo effects of labral injury so that treatment strategies can be developed accordingly