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A.R.W. Barrett

Bio: A.R.W. Barrett is an academic researcher from Imperial College London. The author has contributed to research in topics: Robotic surgery & Computer-assisted surgery. The author has an hindex of 9, co-authored 15 publications receiving 704 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a prospective, randomised controlled trial of unicompartmental knee arthroplasty with the assistance of a robotic arm was conducted, where the authors compared the performance of the Acrobot system with conventional surgery.
Abstract: We performed a prospective, randomised controlled trial of unicompartmental knee arthroplasty comparing the performance of the Acrobot system with conventional surgery A total of 27 patients (28 knees) awaiting unicompartmental knee arthroplasty were randomly allocated to have the operation performed conventionally or with the assistance of the Acrobot The primary outcome measurement was the angle of tibiofemoral alignment in the coronal plane, measured by CT Other secondary parameters were evaluated and are reported All of the Acrobot group had tibiofemoral alignment in the coronal plane within 2 degrees of the planned position, while only 40% of the conventional group achieved this level of accuracy While the operations took longer, no adverse effects were noted, and there was a trend towards improvement in performance with increasing accuracy based on the Western Ontario and McMaster Universities Osteoarthritis Index and American Knee Society scores at six weeks and three months The Acrobot device allows the surgeon to reproduce a pre-operative plan more reliably than is possible using conventional techniques which may have clinical advantages

286 citations

Journal ArticleDOI
TL;DR: By refining the CT scanning protocol, the effective radiation dose received by the patient is reduced down to the equivalent of one long-leg standing radiograph, which will be more acceptable to obtain the three-dimensional data set produced by CT scanning.
Abstract: Surgeons need to be able to measure angles and distances in three dimensions in the planning and assessment of knee replacement. Computed tomography (CT) offers the accuracy needed but involves greater radiation exposure to patients than traditional long-leg standing radiographs, which give very little information outside the plane of the image. There is considerable variation in CT radiation doses between research centres, scanning protocols and individual scanners, and ethics committees are rightly demanding more consistency in this area. By refining the CT scanning protocol we have reduced the effective radiation dose received by the patient down to the equivalent of one long-leg standing radiograph. Because of this, it will be more acceptable to obtain the three-dimensional data set produced by CT scanning. Surgeons will be able to document the impact of implant position on outcome with greater precision.

173 citations

Journal ArticleDOI
01 Jan 2007
TL;DR: A specific example is given of an active constraint medical robot, the ACROBOT system, used in a prospective randomized controlled trial of unicondylar robotic knee arthroplasty in which the robot was compared to conventional surgery.
Abstract: A brief history of robotic systems in knee arthroplasty is provided. The place of autonomous robots is then discussed and compared to more recent 'hands-on' robotic systems that can be more cost effective. The case is made for robotic systems to have a clear justification, with improved benefits compared to those from cheaper navigation systems. A number of more recent, smaller, robot systems for knee arthroplasty are also described. A specific example is given of an active constraint medical robot, the ACROBOT system, used in a prospective randomized controlled trial of unicondylar robotic knee arthroplasty in which the robot was compared to conventional surgery. The results of the trial are presented together with a discussion of the need for measures of accuracy to be introduced so that the efficacy of the robotic surgery can be immediately identified, rather than have to wait for a number of years before long-term clinical improvements can be demonstrated.

71 citations

Journal ArticleDOI
30 Oct 2006
TL;DR: The concepts and benefits of hands-on robotic surgery and active-constraint robotics are introduced, and the case is made for robotic systems to have a clear justification, with benefits compared to those from cheaper navigation systems.
Abstract: The concepts and benefits of hands-on robotic surgery and active-constraint robotics are introduced. The argument is made for systems to be cost effective and simple in order that they can be justified for a large range of surgical procedures. The case is made for robotic systems to have a clear justification, with benefits compared to those from cheaper navigation systems. The need to have robust systems, that require little surgical training and no technical presence in the operating room, is also discussed. An active constraint medical robot, the Acrobot System, is described together with its use in a prospective randomized controlled trial of unicondylar knee arthroplasty (UKA), comparing the performance of the Acrobot System with conventional surgery. Twenty-eight patients awaiting UKA were randomly allocated to have the operation performed conventionally or with the assistance of the Acrobot. The results of the trial are presented together with a discussion of the need for measures of accuracy to be introduced so that the efficacy of the robotic surgery can be immediately identified, rather than having to wait for a number of years before long-term clinical improvements can be demonstrated

66 citations

Journal ArticleDOI
TL;DR: A randomised clinical trial has been completed for uni‐condylar arthroplasty, and shows a significant improvement in accuracy using the Acrobot® hands‐on robotic system.
Abstract: A randomised clinical trial has been completed for uni-condylar arthroplasty. The trial, under the auspices of the UK MHRA, comprised 15 knees of patients undergoing conventional surgery, and 13 knees of patients who had robotic surgery using the Acrobot hands-on robotic system. The results of the trial were checked by comparing post-op CT scans with pre-op CT-based plans, and show a significant improvement in accuracy using the robot. The technical concept of the Acrobot approach is also described. Details of the complete system are outlined, including the pre-operative planner. The plan incorporates 3D CT models of the leg, together with CAD models of prostheses that can be used to plan the leg alignment, position the prostheses, plan the shape of the cuts required and generate the regions within which cuts must be constrained. The robotic system is also described, together with the methods for locating, clamping, cutting and monitoring the patient. An outline is given of the means by which the preoperative model is registered or aligned to the intra-operative position of the patient and of the robot, without the need for fiducial markers. Results of the randomised clinical trial are also discussed.

47 citations


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Patent
18 May 2007
TL;DR: In this article, a method for controlling a surgical device is presented, which includes manipulating the surgical device to perform a procedure on a patient, determining whether a relationship between an anatomy of the patient and a position, an orientation, a velocity, and/or an acceleration of a surgical tool corresponds to a desired relationship between the anatomy and the position, the orientation, the velocity and or the acceleration of the surgical tool.
Abstract: A method for controlling a surgical device is provided. The method includes manipulating the surgical device to perform a procedure on a patient; determining whether a relationship between an anatomy of the patient and a position, an orientation, a velocity, and/or an acceleration of a surgical tool of the surgical device corresponds to a desired relationship between the anatomy and the position, the orientation, the velocity, and/or the acceleration of the surgical tool; and imposing a constraint on the surgical device if the relationship does not correspond to the desired relationship and/or a detection device is unable to detect a position of the anatomy and/or the position of the surgical tool.

673 citations

Journal ArticleDOI
TL;DR: Steeply-inclined acetabular components, with abduction angles greater than 55 degrees, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions, probably due to a greater risk of edge-loading.
Abstract: We examined the relationships between the serum levels of chromium and cobalt ions and the inclination angle of the acetabular component and the level of activity in 214 patients implanted with a metal-on-metal resurfacing hip replacement. Each patient had a single resurfacing and no other metal in their body. All serum measurements were performed at a minimum of one year after operation. The inclination of the acetabular component was considered to be steep if the abduction angle was greater than 55°. There were significantly higher levels of metal ions in patients with steeply-inclined components (p = 0.002 for chromium, p = 0.003 for cobalt), but no correlation was found between the level of activity and the concentration of metal ions. A highly significant (p < 0.001) correlation with the arc of cover was found. Arcs of cover of less than 10 mm were correlated with a greater risk of high concentrations of serum metal ions. The arc of coverage was also related to the design of the component and to size as well as to the abduction angle of the acetabular component. Steeply-inclined acetabular components, with abduction angles greater than 55°, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions. This is probably due to a greater risk of edge-loading.

536 citations

Journal ArticleDOI
TL;DR: Clinical applications in neurosurgery, orthopedics, and the cardiac and thoracoabdominal areas are discussed, together with a description of an evolving technology named Natural Orifice Transluminal Endoscopic Surgery.
Abstract: Image-guided interventions are medical procedures that use computer-based systems to provide virtual image overlays to help the physician precisely visualize and target the surgical site. This field has been greatly expanded by the advances in medical imaging and computing power over the past 20 years. This review begins with a historical overview and then describes the component technologies of tracking, registration, visualization, and software. Clinical applications in neurosurgery, orthopedics, and the cardiac and thoracoabdominal areas are discussed, together with a description of an evolving technology named Natural Orifice Transluminal Endoscopic Surgery (NOTES). As the trend toward minimally invasive procedures continues, image-guided interventions will play an important role in enabling new procedures, while improving the accuracy and success of existing approaches. Despite this promise, the role of image-guided systems must be validated by clinical trials facilitated by partnerships between scientists and physicians if this field is to reach its full potential.

388 citations

Journal ArticleDOI
TL;DR: Computerized tomographic scans of the axial and appendicular skeleton are associated with substantially elevated radiation exposures, but the effective dose declines substantially for anatomic structures that are further away from the torso.
Abstract: Background: Computerized tomographic scans are routinely obtained to evaluate a number of musculoskeletal conditions. However, since computerized tomographic scans expose patients to the greatest amounts of radiation of all imaging modalities, the physician must be cognizant of the effective doses of radiation that are administered. This investigation was performed to quantify the effective doses of computerized tomographic scans that are performed for various musculoskeletal applications. Methods: The digital imaging archive of a single institution was retrospectively reviewed to identify helical computerized tomographic scans that were completed to visualize the extremities or spine. Imaging parameters were recorded for each examination, and dosimetry calculator software was used to calculate the effective dose values according to a modified protocol derived from publication SR250 of the National Radiological Protection Board of the United Kingdom. Computerized tomographic scans of the chest, abdomen, and pelvis were also collected, and the effective doses were compared with those reported by prior groups in order to validate the results of the current study. Results: The mean effective doses for computerized tomographic scans of the chest, abdomen, and pelvis (5.27, 4.95, and 4.85 mSv, respectively) were consistent with those of previous investigations. The highest mean effective doses were recorded for studies evaluating the spine (4.36, 17.99, and 19.15 mSv for the cervical, thoracic, and lumbar spines, respectively). In the upper extremity, the effective dose of a computerized tomographic scan of the shoulder (2.06 mSv) was higher than those of the elbow (0.14 mSv) and wrist (0.03 mSv). Similarly, the effective dose of a hip scan (3.09 mSv) was significantly higher than those observed with knee (0.16 mSv) and ankle (0.07 mSv) scans. Conclusions: Computerized tomographic scans of the axial and appendicular skeleton are associated with substantially elevated radiation exposures, but the effective dose declines substantially for anatomic structures that are further away from the torso.

388 citations

Journal ArticleDOI
TL;DR: Clinical requirements and technical challenges related to the design of robotic platforms for flexible access surgery, including instrument design, intraoperative guidance, and intelligent human-robot interaction are discussed.
Abstract: Recent technological advances in surgery have resulted in the development of a range of new techniques that have reduced patient trauma, shortened hospitalization, and improved diagnostic accuracy and therapeutic outcome. Despite the many appreciated benefits of minimally invasive surgery (MIS) compared to traditional approaches, there are still significant drawbacks associated with conventional MIS including poor instrument control and ergonomics caused by rigid instrumentation and its associated fulcrum effect. The use of robot assistance has helped to realize the full potential of MIS with improved consistency, safety and accuracy. The development of articulated, precision tools to enhance the surgeon's dexterity has evolved in parallel with advances in imaging and human-robot interaction. This has improved hand-eye coordination and manual precision down to micron scales, with the capability of navigating through complex anatomical pathways. In this review paper, clinical requirements and technical challenges related to the design of robotic platforms for flexible access surgery are discussed. Allied technical approaches and engineering challenges related to instrument design, intraoperative guidance, and intelligent human-robot interaction are reviewed. We also highlight emerging designs and research opportunities in the field by assessing the current limitations and open technical challenges for the wider clinical uptake of robotic platforms in MIS.

328 citations