Publications
284 results found
Cobb JP, Kannan V, Dandachli W, et al., 2008, Learning how to resurface cam-type femoral heads with acceptable accuracy and precision: The role of computed tomography-based navigation, 1st Annual United States Comprehensive Course on Total Hip Resurfacing Arthroplasty, Pages: 57-64
Background: Resurfacing arthroplasty for cam-type deformities, which are a common cause of early osteoarthritis, is a technically demanding operation. Like any other arthroplasty, it requires both accuracy and precision. On the basis of the results of series reported by expert surgeons, we considered it desirable that this operation should be performed within +/- 10 degrees of the desired angular orientation and +/- 6 mm of entry-point translation in 95% of hips. Technological aids are now available to help surgeons achieve that level of accuracy. Three models of cam-type hips of increasing severity were used to assess the efficacy of three systems of instrumentation at delivering the required level of accuracy and precision.Methods: Thirty-two students of surgical technology were instructed in hip resurfacing and shown detailed plans of the desired operative outcome for the three hips with cam-type deformity. They then used conventional instruments, imageless navigation, and computed tomography-based navigation to perform the operation as accurately as possible.Results: Conventional instrumentation produced an unacceptably wide range of entry-point errors. Imageless navigation was able to deliver adequate accuracy and precision in varus-valgus angulation and superoinferior translation, but was less satisfactory in version and anteroposterior translation. Computed tomography-based navigation enabled novice surgeons to navigate hips that had difficult cam-type deformity with acceptable precision in all four degrees of freedom measured.Conclusions: Only computed tomography-based navigation appears to be appropriate for delivering both the accuracy and the precision needed by surgeons on the steep part of their learning curve. Neither conventional neck-based instrumentation nor imageless navigation provided enough help for novice surgeons learning to perform this technically challenging operation.Clinical Relevance: Training with this computed tomography-based navigati
Dandachli W, Nakhla A, Iranpour F, et al., 2008, Can the acetabular position be derived from a pelvic frame of reference?, Clin Orthop Rel Res
Kogianni G, Eleftheriou K, Waxman J, et al., 2008, OC6. Endo180 function in metastatic prostate cancer bone lesions, Cancer Treatment Reviews, VII International Meeting on Cancer Induced Bone Disease, Publisher: Elsevier Ltd, Pages: 51-52
Cobb JP, 2008, Computer assistance will improve your surgery, 13th ESSKA Congress
Cobb JP, 2008, Accuracy and precision in orthopaedics, Visiting Professor 2008
Iranpour F, Merican AM, Amis AA, et al., 2008, The width:thickness ratio of the patella: an aid in knee arthroplasty., Clin Orthop Relat Res., Vol: 466(5), Pages: 1198-1203
Establishing the appropriate size of the patellar implant-bone composite is one of the important steps ensuring functional success in arthroplasty. Conventionally, the patella is measured intraoperatively and its thickness is used to guide the depth of resection. However, in a diseased joint, this may not reflect the native patellar thickness. We studied the relationship between the patellar thickness and various patellar dimensions on three-dimensional reconstructed computed tomographic scans from 37 normal adult knees. Patellar width correlated with thickness. The average patellar width:thickness ratio was 2.0 (standard deviation, 0.106; 95% confidence interval, 1.96-2.03). The cartilage thickness was on average 2.5 mm (standard deviation, 1.0). The width:thickness ratio was similar in 79 digital radiographs taken before TKA of knees without patellofemoral disease (mean, 2.1; standard deviation, 0.28). When compared with the two other methods for calculating patellar resection described in the literature, the width:thickness ratio was more reliable. The width:thickness ratio appears anatomically constant and may be a useful guide for estimating premorbid patellar thickness.
Cobb JP, 2008, Navigating the acetabulum in trauma tumour and arthroplasty, CAOS International - Italy
Kogianni G, Eleftheriou K, Waxman J, et al., 2008, Endo180 function in metastatic prostate cancer bone lesions, 7th International Meeting on Cancer Induced Bone Disease, Publisher: ELSEVIER SCI LTD, Pages: S51-S52, ISSN: 0305-7372
Cobb JP, Kannan V, Brust K, et al., 2007, Navigation reduces the learning curve in resurfacing total hip arthroplasty, CLINICAL ORTHOPAEDICS AND RELATED RESEARCH, Pages: 90-97, ISSN: 0009-921X
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- Citations: 57
Cobb JP, 2007, Computer navigation <i>versus</i> conventional total knee replacement, JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 89B, Pages: 1130-1130, ISSN: 0301-620X
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- Citations: 1
Barrett ARW, Davies BL, Gomes M, et al., 2007, Coputer-assisted hip resurfacing surgery using the Acrobot Navigation System, J Engineering in Medicine, Vol: 221, Pages: 773-785, ISSN: 0954-4119
The authors have previously reported on the laboratory development of the Acrobot Navigation System for accurate computer-assisted hip resurfacing surgery. This paper describes the findings of using the system in the clinical setting and including the improvements that have been made to expedite the procedure. The aim of the present system is to allow accurate planning of the procedure and precise placement of the prosthesis in accordance with the plan, with a zero intraoperative time penalty in comparison to the standard non-navigated technique. At present the navigation system is undergoing final clinical evaluation prior to a clinical study designed to demonstrate the accuracy of outcome compared with the conventional technique. While full results are not yet available, this paper describes the techniques that will be used to evaluate accuracy by comparing pre-operative computed tomography (CT)-based plans with post-operative CT scans. Example qualitative clinical results are included based on visual comparison of the plan with post-operative X-rays.
Davies BL, Rodriguez y Baena F, Barrett AR, et al., 2007, Robotic control in knee joint replacement surgery, Vol: 221, Pages: 71-80, ISSN: 0954-4119
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.
J Cobb, 2007, Hands-on Robotic Unicompartmental Knee Replacement, Navigation and MIS, Editors: Stiehl, Konermann, lll, Germany, Publisher: Springer, Pages: 284-296, ISBN: 978-3-540-36690-4
Dandachli W, Richards R, Sauret V, et al., 2006, The transverse pelvic plane: a new and practical reference frame for hip arthroplasty., Comput Aided Surg, Vol: 11, Pages: 322-326, ISSN: 1092-9088
Acetabular orientation is a crucial part of the planning and performance of hip arthroplasty. Currently, most surgeons use the anterior pelvic plane (APP) to orient themselves when navigating the acetabulum, despite the fact that the anterior superior iliac spine (ASIS) of the unaffected side is not accessible in the lateral position. We have identified another plane, the transverse pelvic plane (TPP), relying on both posterior superior iliac spines and the ASIS of the affected side. In a CT-based study, this plane was found to be as reliable as the APP for the orientation of the cup in both anteversion and inclination. The substantial variation in both measurements between patients is documented, and their relation to the "safe zone" is shown. We recommend consideration of the TPP by surgeons who perform arthroplasty in the lateral position. It may reduce operating time and improve accuracy in computer-assisted arthroplasty.
Henckel J, Richards R, Lozhkin K, et al., 2006, Very low-dose computed tomography for planning and outcome measurement in knee replacement - The imperial knee protocol, J Bone Joint Surg Br, Vol: 88B, Pages: 1513-1518, ISSN: 0301-620X
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.
Davies BL, Jakopec M, Harris S, et al., 2006, Active-constraint robotics for surgery, PROCEEDINGS OF THE IEEE, Vol: 94, Pages: 1696-1704, ISSN: 0018-9219
Brian Davies, Matjaz Jakopec, Simon J Harris, et al., 2006, Active-constraint Robotics for Surgery, Proceedings of the IEEE, Vol: 94, Pages: 1969-1704, ISSN: 0018-9219
Cobb J, Henckel J, Gomes P, et al., 2006, Hands-on robotic unicompartmental knee replacement - A prospective, randomised controlled study, Journal of Bone and Joint Surgery, Vol: 88-B, Pages: 188-197, ISSN: 0301-620X
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.
Davies BL, Rodriguez F, Jakopec M, et al., 2006, The Acrobot® system for robotic mis total knee and uni-condylar arthroplasty, International Journal of Humanoid Robotics, Vol: 3, Pages: 417-428, ISSN: 0219-8436
The concept of the Acrobot® system is described. The technical details of the complete system are then outlined, including the pre-operative planner which incorporates 3D CT models 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 and clamping 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. Post-operative results are given, for both total knee replacement and also for the more recent clinical trials using a minimally invasive robotic procedure for uni-condylar arthroplasty. © 2006 World Scientific Publishing Company.
Harris S, Jakopec M, Rodriguez y Baena F, et al., 2006, Results of a regulated clinical trial of the Acrobot Sculptor Hands-On Robotic System for unicompartmental knee arthroplasty, Computer Assisted Orthopaedic Surgery UK, 1st Annual Meeting of CAOSUK, 10 - 11 February 2006, London Heathrow, UK, Pages: 21-21
Cobb J, Henckel J, Gomes P, et al., 2006, Preoperative planning and intra-operative guidance for accurate computer-assisted minimally-invasive hip resurfacing surgery, Journal of Engineering in Medicine, Proceedings of the Institution of Mechanical Engineers, Part H, ISSN: 0954-4119
Brian Davies, Ferdinando Rodriguez, Matja Jakopec, et al., 2006, The Acrobot® System for Robotic MIS Total Knee and Uni-Condylar Arthroplasty, International Journal of Humanoid Robotics, Vol: 3, Pages: 415-428, ISSN: 0219-8436
The concept of the Acrobot® system is described. The technical details of the complete system are then outlined, including the pre-operative planner which incorporates 3D CT models 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 and clamping 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. Post-operative results are given, for both total knee replacement and also for the more recent clinical trials using a minimally invasive robotic procedure for uni-condylar arthroplasty.
Harris S, Jakopec M, Rodriguez y Baena F, et al., 2006, The use of computer tomography (CT) to measure the accuracy of computer assisted knee arthroplasty, Computer Assisted Orthopaedic Surgery UK, 1st Annual Meeting of CAOSUK
Harris S, Jakopec M, Rodriguez y Baena F, et al., 2006, Computer based planning for hip resurfacing surgery, London, Computer Assisted Orthopaedic Surgery UK, 1st Annual Meeting of CAOSUK, Pages: 48-48
Harris S, Jakopec M, Rodriguez y Baena F, et al., 2006, Minimally invasive computer assisted hip resurfaxcing surgery using the Acrobot navigation system, Computer Assisted Orthopaedic Surgery UK, 1st Annual Meeting of CAOSUK, 10 - 11 February 2006, London Heathrow, UK, Pages: 32-32
Rodriguez y Baena F, Cobb J, Henckel J, et al., 2005, Robotic clinical trials of uni-condylar arthroplasty, International Journal of Medical Robotics and Computer Assisted Surgery, Vol: 1, Pages: 20-28, ISSN: 1478-5951
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 (R) 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 (R) 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. Copyright (c) 2005 John Wiley & Sons, Ltd.
Anderson OG, Brookes JAS, Cobb J, 2005, False aneurysm caused by failed fracture fixation., Hospital Medicine, Vol: 66, Pages: 422-423
Anderson OGP, Brookes JAS, Cobb J, 2005, False aneurysm caused by failed fracture fixation, HOSPITAL MEDICINE, Vol: 66, Pages: 422-423, ISSN: 1462-3935
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- Citations: 7
Cobb J P, 2005, Sarcomas of Bone and Soft Tissue, The New Aird's Companion in Surgical Studies, Editors: Kevin, Young, Jonathan, London, Publisher: Churchill Livingstone, ISBN: 9780443072116
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