Objectives: A surgical robot (ROBODOC®) is used for total knee replacement. The same system has been in clinical use for total hip replacement at BGU Frankfurt since 1994 and since March 2000 TKR is another clinical application. The presentation intends to give an overview of the system and of the first experiences in clinical use. Background: The outcome of conventional total knee replacement has always been very dependent on the surgeon’s individual skills and routine. The most common mistakes have been malpositionings and malrotations of the prosthesis, which postoperatively caused varus and valgus malalignments of the lower limb resulting in an incorrect mechanical axis. The system permits a three-dimensional pre-operative planning of the correct axis and rotation as well as the correct implant size. The introperative cutting is entirely executed by the surgical robot according to the preoperative planning. Design / Methods: The ROBODOC® Surgical Assistant System consists of three major components: The pre-operative planning workstation called ORTHODOC®, the surgical robot and the robot control unit that receives the preoperative planning data and controls ROBODOC®. Presently, four titanium pins have to be implanted at the beginning of the procedure, one in the proximal femur, one in the distal femur, one in the proximal and one in the distal tibia. These pins are the landmarks for the following procedures. A CT scan is made of the femoral head, the distal femur and the proximal tibia including all the pins and the ankle. A rod is laid on the patient’s leg to detect the motion during CT scan. The CT data is being transferred to the ORTHODOC® workstation on an optical disk. The ORTHODOC® displays three orthogonal cross-sections of the bone on a high-resolution screen. A manipulation on one of the cross-sections is shown in nearly real-time on the other two cross-sections. The first step is to find all the four pins on the CT scan and to check their position. The next step is to create a femoral and tibial axis using four markers (i.e. proximal and distal femur and proximal an distal tibia). The bone is then aligned along the axis. Once those steps have been performed and implant can be selected from an implant library. The femoral component is the first part of the planning. Once the correct size, alignment and rotation have been found the tibial component is added and adjusted. The final step is to select the tibial liner. Once the planning is finished a synthetic x-ray can be created which shows the postoperative result and helps to determine if the correct axis was planned. After finishing the planning a transfer tape that can be loaded into the ROBODOC® is created. The patient’s leg is positioned using a special leg holder and thigh support plate. The patient’s knee should be flexed to an angle of approximately 70 to 80 degrees, a gap of 1 to 2 mm should be achieved. The patient is prepared and draped in the normal manner. Surgery proceeds normally and the regular approach for TKA is used. Once the exposure is finished and the four pins are clearly accessible, two Steinmann pins are inserted, one in the femur and one in the tibia. The Hoffmann II Orthopedic Fixation System is used to connect the two Steinmann pins and to distract the knee joint. Now the robot is moved to the OR table. The femur and the tibia must be rigidly fixated to the robot base. Following this two bone motion monitors are attached to the bone, one to the femur and one to the tibia. The registration program is started. Using ROBODOC®’s ball probe the four pins have to be located, including the use of pin extenders so that the robot can find the patient’s position on the OR table by comparing the data to the preoperative CT data of that particular patient. First the femoral pins are found, then the tibial pins. If the registration is correct the cutter can be installed, the irrigation system is connected and the robot starts cutting the surface for the planned implant. First the femur is prepared, then the tibia. The final cut is the cruciform in the tibia for which a special cutter is required. Should bone motion occur during any part of the cutting procedure the robot will stop and the pins have to be re-registered. Once the cutting is finished, the robot is moved away from the OR-table, the pins and fixators are removed an the surgeon inserts the planned implant manually – normally using the cementless tecnique. The surgery is finished the traditional way. Fifty patients who had received total knee replacement using the ROBODOC® System were followed up and examined using a pre-defined protocol: 23 patients were male, 27 were female. All cases showed severe signs of osteoarthrosis. In 35 cases we saw a varus deviation, in 13 cases a valgus deviation, in two cases there was no deviation from the axis. four patients were post-traumatic cases, in one case a complex osteotomy had been performed. In 38 patients the cementless technique was used, in eight cases the tibial component was cemented and in four cases both components were cemented due to poor bone quality. We had an obvious learning curve, OR time went down from 130 minutes for the first procedure to 90 minutes average OR time. Due to the three-dimensional pre-operative planning of the correct axis and rotation we saw a good alignment of the femoral and tibial component in all cases. Besides the optimal size of the components could be selected for the patients in this group. Results/Conclusions: The system permits a three-dimensional pre-operative planning of the correct axis and rotation as well as the correct implant size. Due to the exact cut surfaces the cementless technique can be used in the makority of cases. The patients are permitted full weight bearing immediately postoperatively. None of the templates or tools that are needed for manual TKR are necessary when the ROBODOC® system is used which means an immense reduction of surgical tools for that procedure. The OR-time is not significantly longer compared to traditional TKR. The surgeon has total control of the procedure at all times and the procedure can be finished manually if necessary. Correct aligment and rotation are the known preconditions for durability in TKR. The present disadvantages of the system are soft tissue management including ligament balancing, the rigid fixation and the use of pins (markers). By June 2001 about 280 surgeries have been performed using the system. The development of a pinless system is already on its way and clinical testings are abour to start at BGU Frankfurt

From 01/1988 to 04/2001 224 THR were performed assisted by a surgical robot (ROBODOC). The short term run of 5 years should reveal, if any benefit ore disadvantage could be detected comparing Robodo chips with hand -broached hips. In all 224 cases a straight stem prosthesis with a proximal sleeve was used (S-Rom-Prosthesis). The cup was implanted manually (RM-Cup). The average follow up has been 5 years (4,0–6,2 years). At the last investigation 3 patients had died, 6 patients could not be reached. 215 patients (96%) were examined. According to Merle d’Aubigné pain and walking ability were mesured with a maximal score of 12 points. Robot assisted hip surgery surely offers an improved primary stability of the stem because of the outstanding precision. Missing stem loosening after 5 years seem to promiss a longer survival rate. To avoid a high learning curve certificated qualifying courses are compulsory

The use of robots in orthopaedic surgery is an emerging field that is gaining momentum. It has the potential for significant improvements in surgical planning, accuracy of component implantation and patient safety. Advocates of robot-assisted systems describe better patient outcomes through improved pre-operative planning and enhanced execution of surgery. However, costs, limited availability, a lack of evidence regarding the efficiency and safety of such systems and an absence of long-term high-impact studies have restricted the widespread implementation of these systems. We have reviewed the literature on the efficacy, safety and current understanding of the use of robotics in orthopaedics.

Cite this article: Bone Joint J 2015; 97-B:292–9.

Accurate cup placement in total hip arthroplasty (THA) for the patients with developmental dysplasia of the hip (DDH) is one of the challenges due to distinctive bone deformity. Robotic-arm assisted system have been developed to improve the accuracy of implant placement. This study aimed to compare the accuracy of robotic-arm assisted (Robo-THA), CT-based navigated (Navi-THA), and manual (M-THA) cup position and orientation in THA for DDH.

A total of 285 patients (335 hips) including 202 M-THAs, 45 Navi-THAs, and 88 Robo-THA were analyzed. The choice of procedure followed the patient's preferences. Horizontal and vertical center of rotation (HCOR and VCOR) were measured for cup position, and radiographic inclination (RI) and anteversion (RA) were measured for cup orientation. The propensity score-matching was performed among three groups to compare the absolute error from the preoperative target position and angle.

Navi-THA showed significantly smaller absolute errors than M-THA in RI (3.6° and 5.4°) and RA (3.8° and 6.0°), however, there were no significant differences between them in HCOR (2.5 mm and 3.0 mm) or VCOR (2.2 mm and 2.6 mm). In contrast, Robo-THA showed significantly smaller absolute errors of cup position than both M-THA and Navi-THA (HCOR: 1.7 mm and 2.9 mm, vs. M-THA, 1.6 mm and 2.5 mm vs. Navi-THA, VCOR:1.7 mm and 2.4 mm, vs. M-THA, 1.4 mm and 2.2 mm vs. Navi-THA). Robo-THA also showed significantly smaller absolute errors of cup orientation than both M-THA and Navi-THA (RI: 1.4° and 5.7°, vs. M-THA, 1.5° and 3.6°, vs. Navi-THA, RA: 1.9° and 5.8° vs. M-THA, 2.1° and 3.8° vs. Navi-THA).

Robotic-arm assisted system showed more accurate cup position and orientation compared to manual and CT-based navigation in THA for DDH. CT-based navigation increased the accuracy of cup orientation compared to manual procedures, but not cup position.

Introduction

Robotically-assisted unicondylar knee arthroplasty (UKA) is intended to improve the precision with which the components are implanted, but the impact of alignment using this technique on subsequent polyethylene surface damage has not been determined. Therefore, we examined retrieved ultra-high-molecular-weight polyethylene UKA tibial inserts from patients who had either robotic-assisted UKA or UKA performed using conventional manual techniques and compared differences in polyethylene damage with differences in implant component alignment between the two groups. We aimed to answer the following questions: (1) Does robotic guidance improve UKA component position compared to manually implanted UKA? (2) Is polyethylene damage or edge loading less severe in patients who had robotically aligned UKA components? (3) Is polyethylene damage or edge loading less severe in patients with properly aligned UKA components?

Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate robotic technology in 1992, with the introduction of ROBODOC, for the planning and performance of total hip replacement. The use of robotic systems has subsequently increased, with promising short-term radiological outcomes when compared with traditional orthopaedic procedures. Robotic systems can be classified into two categories: autonomous and haptic (or surgeon-guided). Passive surgery systems, which represent a third type of technology, have also been adopted recently by orthopaedic surgeons.

While autonomous systems have fallen out of favour, tactile systems with technological improvements have become widely used. Specifically, the use of tactile and passive robotic systems in unicompartmental knee replacement (UKR) has addressed some of the historical mechanisms of failure of non-robotic UKR. These systems assist with increasing the accuracy of the alignment of the components and produce more consistent ligament balance. Short-term improvements in clinical and radiological outcomes have increased the popularity of robot-assisted UKR.

Robot-assisted orthopaedic surgery has the potential for improving surgical outcomes. We discuss the different types of robotic systems available for use in orthopaedics and consider the indication, contraindications and limitations of these technologies.

Continuous technical improvement in spinal surgical procedures, with the aim of enhancing patient outcomes, can be assisted by the deployment of advanced technologies including navigation, intraoperative CT imaging, and surgical robots. The latest generation of robotic surgical systems allows the simultaneous application of a range of digital features that provide the surgeon with an improved view of the surgical field, often through a narrow portal. There is emerging evidence that procedure-related complications and intraoperative blood loss can be reduced if the new technologies are used by appropriately trained surgeons. Acceptance of the role of surgical robots has increased in recent years among a number of surgical specialities including general surgery, neurosurgery, and orthopaedic surgeons performing major joint arthroplasty. However, ethical challenges have emerged with the rollout of these innovations, such as ensuring surgeon competence in the use of surgical robotics and avoiding financial conflicts of interest. Therefore, it is essential that trainees aspiring to become spinal surgeons as well as established spinal specialists should develop the necessary skills to use robotic technology safely and effectively and understand the ethical framework within which the technology is introduced. Traditional and more recently developed platforms exist to aid skill acquisition and surgical training which are described. The aim of this narrative review is to describe the role of surgical robotics in spinal surgery, describe measures of proficiency, and present the range of training platforms that institutions can use to ensure they employ confident spine surgeons adequately prepared for the era of robotic spinal surgery. Cite this article: Bone Joint J 2020;102-B(5):568–572

Abstract. Introduction. Total knee replacement (TKR) in patients with skeletal dysplasia is technically challenging surgery due to deformity, joint contracture, and associated co-morbidities. The aim of this study is to follow up patients with skeletal dysplasia following a TKR. Methodology. We retrospectively reviewed 22 patients with skeletal dysplasia who underwent 31 TKRs at our institution between 2006 and 2022. Clinical notes, operative records and radiographic data were reviewed. Results. Achondroplasia was the most common skeletal dysplasia (8), followed by Chondrodysplasia punctata (7) and Spondyloepiphyseal dysplasia (5). There were fourteen men and eight women with mean age of 51 years (28 to 73). The average height of patients was 1.4 metres (1.16–1.75) and the mean weight was 64.8 Kg (34.3–100). The mean follow up duration was 68.32 months (1–161). Three patients died during follow up. Custom implants were required in twelve patients (38.71%). Custom jigs were utilised in six patients and two patients underwent robotic assisted surgery. Hinged TKR was used in seventeen patients (54.84%), posterior stabilised TKR in nine patients (29.03%), and cruciate retaining TKR in five patients (16.13%). One patient underwent a patella resurfacing for persistent anterior knee pain and another had an intra-operative medial tibial plateau fracture which was managed with fixation. No revisions occurred during the follow up period. Conclusion. Despite the technical challenges and complexity of TKR within this unique patient group, we demonstrate good implant survivorship during the study period. Cross sectional imaging is recommended preoperatively for precise planning and templating

Glenoid replacement is a manual bone removal procedure that can be difficult for surgeons to perform. Surgical robotics have been utilized successfully in hip and knee orthopaedic procedures but there are no systems currently available in the shoulder. These robots tend to have low adoption rates by surgeons due to high costs, disruption of surgical workflow and added complexity. As well, these systems typically use optical tracking which needs a constant line-of-sight which is not conducive to a crowded operating room. The purpose of this work was developing and testing a surgical robotic system for glenoid replacement. The new surgical system utilizes flexible components that tether a Stewart Platform robot to the patient through a patient specific 3D printed mount. As the robot moves relative to the bone, reaction loads from the flexible components bending are measured by a load cell allowing the robot to “feel” its way around. As well, a small bone burring tool was attached to the robot to facilitate the necessary bone removal. The surgical system was tested against a fellowship-trained surgeon performing standard surgical techniques. Both the robot and the surgeon performed glenoid replacement on two different scapula analogs: standard anatomy and posterior glenoid edge wear referred to as a Walch B2. Six of each scapula model was tested by the robot and the surgeon. The surgeon created a pre-operative plan for both scapula analogs as a target for both methodologies. CT scans of the post-operative cemented implants were compared to the pre-operative target and implant position and orientation errors were measured. For the standard shoulder analogs the net implant position and orientation errors were 1.47 ± 0.48 mm and 2.57 ± 2.30° for the robot and 1.61 ± 0.29 mm and 5.04 ± 1.92° for the surgeon respectively. For the B2 shoulders, the net implant position and orientation errors were 2.16 ± 0.36 mm and 2.89 ± 0.88° for the robot and 3.01 ± 0.42 mm and 4.54 ± 1.49° for the surgeon respectively. The new tracking system was shown to be able to match or outperform the surgeon in most metrics. The surgeon tended to have difficulty gauging the depth needed as well as the face rotation of the implant. This was not surprising as the reaming tool used by the surgeon obscures the view of the anatomy and the spherical cutter hinders the ability to index the tool. The robot utilized only one surgical tool, the bone burr, precluding the need for multiple instruments used by the surgeon to prepare the glenoid bone bed. The force-space navigation method can be generalized to other joints, however, further work is needed to validate the system using cadaveric specimens

Computer assisted orthopaedic surgery (CAOS) is an emerging and expanding filed. There are some old classification systems that are too comprehensive to cover all new CAOS tools and hybrid devises that are currently present and others that are expected to appear in the near future. Based on our experience and on the literature review, we grouped CAOS devises on the basis of their functionality and clinical use into 6 categories, which are then sub-grouped on technical basis. In future, new devices can be added under new categories or subcategories. This grouping scheme is meant to provide a simple guide on orthopaedic systems rather than a comprehensive classification for all computer assisted systems in surgical practice. For example, the number and diversity of tasks of surgical robots is enormous, up to 159 surgical robots with different mechanisms and functions reported in the literature. These can be classified according to their tasks, mechanism of actions, degree of freedom and level of activity but for the purpose of simplicity we subcategorised the orthopaedic robots to only industrial, hand-held and bone-mounted. Table 1 shows the classification system with the 6 categories and other subcategories

Introduction. Innovations in surgical robotics and navigation have significantly improved implant placement accuracy in total knee arthroplasty (TKA). However, many comparative studies have not been shown to substantially improve revision rates or other clinical outcome scores. We conducted a simulation study based on the reported distribution of patient-specific characteristics and estimated potential effect of coronal plane alignment (CPA) on risk of revision to evaluate the hypothesis that most published study designs in this area have been too underpowered to detect improvements in revision rates. Methods. To model previously reported studies, we generated a series of simulated TKA patient populations, assigning each patient a set of patient-specific factors (age at index surgery, BMI, and sex (Fig.1a)), as well as one surgeon-controlled factor (CPA) (Fig.1b) based on registry data and published literature. We modelled the survival probability for an individual patient at time t as a Gaussian function (exp[-(t/(k∗τ. max. )). 2. ]), where τ. max. (99.5 years) is selected to ensure the mean survival probability of the patient population matched 92% at 15 years. The value of k was adjusted for simulated patients within a range of 0 to 1 as a function of their patient and surgeon-specific factors (Fig.2). To evaluate power associated with a study design, we ran a Monte Carlo simulation generating 10,000 simulated populations of ten different cohort sizes. We divided the patient population into two groups: one group was assigned CPAs governed by the precision of a navigated/robotic approach (σ=1.5°), and the other CPAs governed by the precision of a conventional approach (σ=3°). We then simulated the time to failure for each patient, computed the corresponding Kaplan-Meier survival curves, and applied a Log-Rank test to each study to test for statistical difference. From the 10,000 simulations associated with each cohort size, we determined the percentage of simulated studies that found a statistically significant difference at each time point. Results. Figure 3 shows a contour plot illustrating the probability that a survival analysis with a specific study design would find statistical significance between the conventional and navigated/robotic patient groups. Entries from recently published literature are overlaid for context. No studies achieved statistical significance (p<0.05). Discussion. The effectiveness of navigated/robotic surgery is one of the most controversial debates in orthopedic surgery. The results from this simulation suggest that most revision studies aiming to settle this debate are likely significantly underpowered, falling below the normal 80% threshold. Limitations of this analysis include using only a single surgeon-controlled variable in the survival simulation, and only a single precision for the navigated/robotic approaches. Further studies will include more implant-related risk factors and a wider range of precisions for navigated/robotic procedures. Based on this simulation, it appears the effect size afforded by navigated/robotic surgeries on revision rates in TKA surgery is too small to recommend broad application, especially since adoption could involve added costs and unforeseen risks associated with novelty. Clinically, it may be beneficial to examine the use of robotics/navigation on high-risk patients, where studies are likely to have higher power due to larger effect sizes. For any figures or tables, please contact the authors directly

The first generation of surgical robots which has been used in orthopaedics was characterized by automatic performance of certain tasks like milling of bone cavities or planes. These systems have not been successful as their application and operation suffered from a number of unacceptable drawbacks. Presently computer assisted surgery is dominated by surgical navigation systems where position and orientation of manually guided instruments are visualized on a computer screen as an overlay to the picture of the anatomical structure. However, new concepts of surgical robots make the benefits of using robotic systems more evident. Such robots do not operate automatically but are designed as assistance systems which support the surgeon by interactive operating modes. Compared to manual instrument guidance in pure navigation they offer several additional advantages some of which are particularly valuable to support less or minimal invasive operating techniques. No problems due to tremor or unintentional slipping of the tool. Precise drilling or reaming by stable tool guidance, surgery will be exact and reproducible to achieve pre-operatively planned targets, to overcome the ergonomic problems, such as difficult hand-eye-coordination and frequent changes of viewing direction. The application of interactive assistance robots in orthopaedic and trauma surgery is illustrated by describing exemplary procedures

Only limited data exists concerning outcomes after total knee arthroplasty (TKA) using a surgical robot. We conducted this study to evaluate the clinical and radiographical results in robotic-assisted implantation of TKAs with a minimum follow-up of two years. A total of 50 primary TKAs using ROBODOC were included in this study. The mean duration of follow-up was 28.3 months. The radiographic measurement with regard to the change of mechanical axis, and the inclination of the femoral and tibial components were assessed. The value within ± 3° of optimum was classified to be “acceptable”, and the value exceeding more than ± 3° to be “outlier” results. Also we evaluated clinical results with the range of motion (ROM), Hospital for Special Surgery (HSS) scores, and Western Ontario and McMaster University (WOMAC) scores. The mechanical axis was changed from 6.57 varus to 0.81 valgus. Mean coronal inclination of the femoral and tibial component were 88.61 and 89.76 at the last follow up. Also, mean sagittal inclination of the femoral and tibial component were 0.82 and 85.49. On the other hand, all prostheses had no radiolucent lines. On the clinical assessment, the range of motion improved from 124.9 to 128.4, and the improvement of HSS score and Womac score were 70.06 to 95.72 and 65.64 to 28.92 in each. No major adverse events related to the use of the robotic system have been observed. However, one case of the formation of seroma around the pin track and two cases of the partial abrasion of patellar tendon occurred in relation to procedures. A surgical robot system in TKAs provides good clinical and radiographical results at least 2 years follow-up, however further study for the long term follow-up may be needed. A clear advantage of robot-assisted TKA seems to be ability to execute a highly precise preoperative planning and intraoperaive procedures. But current disadvantages such as increased operating times and inability of adjusting the preoperative planning during the procedure have to be resolved in the future

Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the uncommon tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These can result in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. Two year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the using the robot to complete the procedure. Report the clinical outcomes with robotic total knee replacement at or beyond two years to demonstrate no delayed effect on expected outcome. Methods. The initial consecutive series of 65 Triathlon. TM. total knee replacements using a semi-active haptic guided system that were performed after commercialization that would be eligible for two year follow-up were reviewed. Pre-operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament, patellar tendon, or a neurovascular structure from the cutting tool. Operative notes were also reviewed to determine if the robotic procedure was partially or completely aborted due to any issue. Knee Society Knee Scores (KS-KS) and Functional Scores (KS-FS) were recorded from pre-operative and yearly. Any complications were recorded. Results. 40 cases had two year follow-up. The average follow-up for this series was 1.51 years. No cases were unable to be completed robotically. No case had evidence for acute or delayed injury to the medial collateral ligament, patellar tendon, or neurovascular structure. The only complication was a revision total knee for tibial component loosening after a fall induced periprosthetic tibial fracture. Average pre-operative KS-KS and KS-FS improved from 46.9 and 52.1 to 99.2 and 88.6 at one year follow-up, 100.5 and 86.9 at two year follow-up. Conclusions. A semi-active haptic guided robotic system is a safe and reliable method to perform total knee replacement surgery. This series of initial robotic arm assisted surgery had no intraoperative or delayed soft tissue injuries. Preliminary short-term outcomes at up to two years show excellent outcomes

Background. Manually instrumented knee arthroplasty is associated with variability in implant and limb alignment and ligament balance. When malalignment, patellar maltracking, soft tissue impingement or ligament instability result, this can lead to decreased patient satisfaction and early failure. Robotic technology was introduced to improve surgical planning and execution. Haptic robotic-arm assisted total knee arthroplasty (TKA) leverages three-dimensional planning, optical navigation, dynamic intraoperative assessment of soft tissue laxity, and guided bone preparation utilizing a power saw constrained within haptic boundaries by the robotic arm. This technology became clinically available for TKA in 2016. We report our early experience with adoption of this technique. Methods. A retrospective chart review compared data from the first 120 robotic-arm assisted TKAs performed December 2016 through July 2018 to the last 120 manually instrumented TKAs performed May 2015 to January 2017, prior to introduction of the robotic technique. Level of articular constraint selected, surgical time, complications, hemoglobin drop, length of stay and discharge disposition were collected from the hospital record. Knee Society Scores (KSS) and range of motion (were derived from office records of visits preoperatively and at 2-weeks, 7-weeks and 3-month post-op. Manipulations under anesthesia and any reoperations were recorded. Results. Less articular constraint was used to achieve balance in the robotic group, with a higher incidence of cruciate retaining retention (92% vs. 55%, p < 0.01) and a trend towards lower use of varus-valgus constrained articulations (5% vs. 11%, p = 0.068). Robotic surgery increased mean operative time by 22 minutes (p < 0.001). Operative time improved by 26 minutes from the first 10 robotic cases to the last 10 robotic cases. The robotic group had a lower hospital length of stay (2.7 vs. 3.4 days, p < 0.001). Discharge home was not significantly different between robotic and manual groups (89% vs. 83%, p = 0.2). Postoperative Knee Society scores were similar between groups at each postoperative time interval. Robotic-arm assisted TKA patients demonstrated lower mean flexion contracture at 2-weeks (1.8 vs. 3.3 degrees, p < 0.01), 7-weeks (1.0 vs. 1.8 degrees, p <0.01), and 3-months (0.6 vs 2.1 degrees, p = 0.02) post-surgery, but these differences were small. Mean flexion did not differ between groups at 3-month follow-up, but motion was achieved with a significantly lower rate of manipulation under anesthesia in the robotic group (4% vs 17%, p = 0.013). Conclusion. Preliminary findings demonstrate robotic-arm assisted TKA is safe and efficacious with outcomes comparable, if not superior, to that of manually instrumented TKA. Keywords. total knee arthroplasty, robotic arm-assisted total knee arthroplasty. For any figures or tables, please contact authors directly

Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the lack of tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These damages to the soft tissues resulted in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. One year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the robotic assisted procedure and resort to the use of conventional implantation. Report the clinical outcomes with robotic total knee replacement at or beyond one year to demonstrate satisfactory to excellent performance. Methods. The initial consecutive series of 100 robotic total knee replacements using a semi-active haptic guided system including 34 from the initial IDE series in 2014 and those performed after commercial approval beginning in 2016 were reviewed. Pre- operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament, patellar tendon, or a neurovascular structure from the cutting tool. Operative notes were also reviewed to determine if the robotic procedure was partially or completely aborted due to any issue. Knee Society and Functional scores were recorded from pre-operative and yearly. Results. No cases were unable to be completed robotically. No case had evidence for acute or delayed injury to the medial collateral ligament, patellar tendon, or neurovascular structure. The average follow-up for this series was 1.54 years. Average pre- operative Knee Society and Functional Scores improved from 44.7 and 50 to 98.1 and 87.8 at one year follow-up, 93.8 and 83.1 at two year follow-up, 98.5 and 87.7 at three year follow-up, and 99 and 85 at four year follow-up. Conclusions. A semi-active haptic guided robotic system is a safe and reliable method to perform total knee replacement surgery. Preliminary short-term outcomes data shows excellent clinical and functional results

Hap Paul was a unique individual. It is appropriate that this award should go a unique paper presented at this year’s ISTA. The name “Hap” comes from his initials Howard A. Paul. He was an outstanding veterinarian, but he was also much more than that. He had an insatiable curiosity combined with a quick mind and a surgeon’s practicality. His first love was research. After graduating from high school in Connecticut, he went to Notre Dame as a swimmer. He graduated with a degree in Microbiology and a strong desire to “cure cancer”. Acting on his dreams, as he always did, he decided to go to Paris to work with one of the pioneers of Interferon research. Never mind that he didn’t have a job and did not know a word of French. Of course he got the job and learned French playing rugby (hence his awful accent and colorful vocabulary). The funding ran out for the Interferon research, but he somehow got a shot at a spot in the veterinary school in Paris. He got married and finished his veterinary training. The veterinary thing worked out, but the marriage didn’t. He returned to the US after 9 years living in France, to attend the UC Davis School of Veterinary Science as a surgical resident in the small animal area. He met his wife, Dr. Wendy Shelton there… but that is another story. I met Hap when I was a new attending orthopaedic surgeon at UC Davis and looking to do some animal modeling of hip replacement revision techniques. He was an imposing figure: six feet four, big curly afro and wire glasses. He dressed like a Frenchman, wore big clogs and carried a purse. Needless to say I was intimidated initially. But, he had great joi de vive and lived up to his name… he was almost always happy. Hip replacement in dogs began in the 1970’s, but was nearly abandoned by the early 1980’s because of infections and “luxations” (dislocations). In order to develop an animal model we had to develop instruments and techniques that incorporated “third generation” cementing techniques. This we did, but Hap took these instruments and began using them clinically on working dogs. He developed quite a reputation for resurrecting hip replacements for dogs in the US and internationally. Hap and I went on to develop dog models for CT-based custom implants and later surgical robotics (eventually leading to the development of Robodoc). Despite our academic interests, both Hap and I went into private practice in the mid 1980’s… separately, of course (he as a veterinary orthpaedic surgeon and I specialized in hip and knee replacements for humans). Our research in surgical robotics took off when we landed a huge grant from IBM. But then the sky fell in when we learned that Hap had developed lymphoma. After surgery, radiation and chemotherapy, he was in remission, but temporarily couldn’t perform surgery due to a peripheral neuropathy attributed to Vincristine. So Hap went to the lab at UC Davis to work directly with the robotics team. He was a slave driver… but a pleasant one. Certainly the basic research behind Robodoc could not have been done without Hap getting lymphoma. Over 5 years (1986–91) we both had a ball working with some of the best minds in robotics and imaging research. We presented our research on CT-based customs and robotics at many international venues, and Hap made many friends… some are in the audience today. He was one of the founders of this organization (ISTA). Hap returned to veterinary practice when he could finally work with his hands again… but this was not for long. Soon our research lead to the founding of Integrated Surgical Services (ISS) in 1991, the makers of Robodoc. Hap agreed to leave his practice to lead the company and I stayed in clinical practice to develop and utilize the device on patients. In 1992, we shocked the world by being the first to use an active robot in human surgery. It looked like the dawning of a new age. (I still believe it is, but it has been a very slow dawn). For Hap, the joy was short-lived. He developed leukemia as a complication of his prior chemotherapy. He died while recovering from a bone marrow transplant on Feb. 10, 1993 at the young age of 44. During his short life he contributed tremendously to the benefit of others by his research and development work. But mostly he inspired others to excel in their endeavors. He was a wonderful guy. And we are all pleased to honor him with the presentation of the Hap Paul Award at each year’s meeting of ISTA

Robotic technology in adult reconstruction – initially the placement of the stem during THR – was introduced in the early nineties of last century, starting in the US. The underlying technology dated back to the year 1986. Because of regulatory restrictions the technology could not spread in the US, but was exported to Europe in 1994. There the technology – primarily distributed in Germany – had a great success and by the year 2000 roughly 50 centers were using Robodoc – the first robot on the market – and a very similar German competitor’s product, CASPAR. The initial robot was a crude machine, basically the unchanged beta version. Cumbersome fixation, a registration process using three fiducials, the requirement for second surgery to place the fiducials, and last but not least raw and hardly elaborated cutting files made surgery with Robodoc a demanding undertaking. Yet feedback from the surgeons, sometimes vigorously expressed during regular user meetings, let to continuous evolution of the system and resulted in an advanced and stable technology. Also training – with important input from the already experienced sites – improved significantly, which can best be demonstrated by procedure time for first surgery: in Frankfurt 1994 roughly four hours, while today first surgeries at new sites rarely exceed two hours. Further applications – revision surgery, total knee replacement – helped to justify the significant investment into the system. While robotic technology underwent evolution, other related technologies were developed and entered the market. Main products were the navigation systems, which initially were developed for neurosurgery and spine surgery and which, due to easier handling and lower costs, found more acceptance on behalf of the surgeons. Although the navigation technology in some regards is a step back from the robotic technology, it appealed for just that reason: the surgeon stays in the loop. The surgeon uses the traditional instruments, and the navigator helps him to achieve precision in reaming or placement of implants. In orthopaedic surgery navigators became very popular in TKR, but also in THR. Another development, completely unrelated to the mentioned technology, presented a new challenge: minimal invasive surgery. While in knee surgery the introduction of arthroscopy in the late seventies already proved the feasibility of minimal invasive techniques, adult reconstruction remained the domain of sometimes aggressive and robust surgery. Only recently minimal invasive procedures were introduced and standardized for a couple of applications. It is important to stress the fact that the term ‘minimal invasive’ did not relate to the size of skin incision only, but to the overall degree of soft tissue damage necessary to prepare for and place the implants. Some companies now offer new instruments allowing for very minimal incisions and reduced soft tissue compromise. In contrast to this development robot assisted surgery remained – in spite of numerous improvements – a rather invasive piece of surgery. These separate developments – navigators and minimal invasive surgery – made robot assisted joint surgery in the eyes of many potential users a rather outdated, superfluous and expensive type of technology. It is therefore time to revisit the original intentions that let to the development of robot assisted surgery. The original ideas were sponsored by veterinary surgeons specializing in cementless THR for dogs. They experimented with custom implants, but they identified two fields of concerns: fractures and poor placement. Both problems are – still – common in human THR. Robot-assisted surgery was supposed to mainly address these problems. Another asset of robot-assisted surgery is seen in machine milling, which was invented as part of the robotic procedure and which turned out to be superior to conventional reaming. The published results of robot-assisted THR (i.e. Nishihara et al, 2006) prove that these requirements were met. In our own series in Spain we had no fracture and every single implant was seated according to the preoperative plan. Animal experiments allowing for histological examination of the bone-implant interface showed the uncompromised cancellous scaffolding supporting the implant, while hand-reamed interfaces showed signs of destruction and atrophy. On the other hands there are concerns that current minimal invasive approaches do cause problems in these regards: control of position is mainly feasible by use of intraoperative x-ray, and fractures do occur. Therefore robot-assisted surgery seems to be the ideal complement for the minimal invasive approach. The deficits of MIS regarding orientation and visualization of the surgical object can be compensated by the robots proven ability to execute preoperative established plans. The challenge is the current invasiveness of robotic surgery, which – as primary tests and studies show – can be easily accounted for. In conclusion there is an ever increasing role for robot-assisted surgery in adult reconstruction. It is up to the surgeons to define the requirements and ask for specifications that will meet their and the patient’s expectations regarding the degree of invasiveness involved

One of the more difficult tasks in surgery is to apply the optimal instrument forces and torques necessary to conduct an operation without damaging the tissue of the patient. This is especially problematic in surgical robotics, where force-feedback is totally eliminated. Thus, force sensing instruments emerge as a critical need for improving safety and surgical outcome. We propose a new measurement system that can be used in real fracture surgeries to generate quantitative knowledge of forces/torques applied by surgeon on tissues. We instrumented a periosteal elevator with a 6-DOF load-cell in order to measure forces/torques applied by the surgeons on live tissues during fracture surgeries. Acquisition software was developed in LabView to acquire force/torque data together with synchronised visual information (USB camera) of the tip interacting with the tissue, and surgeon voice recording (microphone) describing the actual procedure. Measurement system and surgical protocol were designed according to patient safety and sterilisation standards. The developed technology was tested in a pilot study during real orthopaedic surgery (consisting of removing a metal plate from the femur shaft of a patient) resulting reliable and usable. As demonstrated by subsequent data analysis, coupling force/torque data with video and audio information produced quantitative knowledge of forces/torques applied by the surgeon during the surgery. The outlined approach will be used to perform intensive force measurements during orthopaedic surgeries. The generated quantitative knowledge will be used to design a force controller and optimised actuators for a robot-assisted fracture surgery system under development at the Bristol Robotics Laboratory