52 results found
Jones G, Clarke S, Harris S, et al., 2019, A novel patient-specific instrument design can deliver robotic level accuracy in unicompartmental knee arthroplasty, The Knee, Vol: 26, Pages: 1421-1428, ISSN: 0968-0160
BackgroundA previous randomised controlled trial (RCT) by our group found that robotic assisted unicompartmental knee arthroplasty (UKA) surgery was significantly more accurate than conventional instrumentation. The aim of this study was to determine whether a low-cost novel PSI design could deliver the same level of accuracy as the robot in the same time efficient manner as conventional instruments.MethodsThirty patients undergoing medial UKA took part. Tibial component position was planned using a low dose CT-scan, and compared to a day 1 postoperative CT-scan to determine the difference between the planned and achieved positions. Operations were performed by one expert surgeon using PSI (Embody, London, UK).ResultsThe mean absolute difference between planned and achieved tibial implant positions using PSI was 2.0° (SD 1.0°) in the coronal plane, 1.8° (SD 1.5) in the sagittal plane, and 4.5° (SD 3.3) in the axial plane. These results were not significantly different to the 13 historical robotic cases (mean difference 0.5°, 0.5°, and 1.7°, p = 0.1907, 0.2867 and 0.1049 respectively). PSI mean operating time was on average 62 min shorter than the robotic group (p < 0.0001) and 40 min shorter than the conventional instrument group (p < 0.0001). No complications were reported.ConclusionsIn conclusion, this clinical trial demonstrates that for tibial component positioning in UKA, a novel design PSI guide in the hands of an expert surgeon, can safely deliver comparable accuracy to a robotic system, whilst being significantly faster than conventional instruments.NIHR Clinical Research Network Reference: 16100.
Uemura K, Boughton O, Logishetty K, et al., 2019, A single-use, size-specific, nylon arthroplasty guide: a preliminary study, Hip International, ISSN: 1120-7000
Jones GG, Logishetty K, Clarke S, et al., 2018, Do patient-specific instruments (PSI) for UKA allow non-expert surgeons to achieve the same saw cut accuracy as expert surgeons?, Archives of Orthopaedic and Trauma Surgery, Vol: 138, Pages: 1601-1608, ISSN: 0936-8051
INTRODUCTION: High-volume unicompartmental knee arthroplasty (UKA) surgeons have lower revision rates, in part due to improved intra-operative component alignment. This study set out to determine whether PSI might allow non-expert surgeons to achieve the same level of accuracy as expert surgeons. MATERIALS AND METHODS: Thirty-four surgical trainees with no prior experience of UKA, and four high-volume UKA surgeons were asked to perform the tibial saw cuts for a medial UKA in a sawbone model using both conventional and patient-specific instrumentation (PSI) with the aim of achieving a specified pre-operative plan. Half the participants in each group started with conventional instrumentation, and half with PSI. CT scans of the 76 cut sawbones were then segmented and reliably orientated in space, before saw cut position in the sagittal, coronal and axial planes was measured, and compared to the pre-operative plan. RESULTS: The compound error (absolute error in the coronal, sagittal and axial planes combined) for experts using conventional instruments was significantly less than that of the trainees (11.6°±4.0° v 7.7° ±2.3º, p = 0.029). PSI improved trainee accuracy to the same level as experts using conventional instruments (compound error 5.5° ±3.4º v 7.7° ±2.3º, p = 0.396) and patient-specific instruments (compound error 5.5° ±3.4º v 7.3° ±4.1º, p = 0.3). PSI did not improve the accuracy of high-volume surgeons (p = 0.3). CONCLUSIONS: In a sawbone model, PSI allowed inexperienced surgeons to achieve more accurate saw cuts, equivalent to expert surgeons, and thus has the potential to reduce revision rates. The next test will be to determine whether these results can be replicated in a clinical trial.
Rivière C, Dhaif F, Shah H, et al., 2018, Kinematic alignment of current TKA implants does not restore the native trochlear anatomy, Orthopaedics and Traumatology: Surgery and Research, Vol: 104, Pages: 983-995, ISSN: 1877-0568
INTRODUCTION: Preserving constitutional patellofemoral anatomy, and thus producing physiological patellofemoral kinematics, could prevent patellofemoral complications and improve clinical outcomes after kinematically aligned TKA (KA TKA). Our study aims 1) to compare the native and prosthetic trochleae (planned or implanted), and 2) to estimate the safety of implanting a larger Persona® femoral component size matching the proximal lateral trochlea facet height (flange area) in order to reduce the native articular surfaces understuffing generated by the prosthetic KA trochlea. METHODS: Persona® femoral component 3D model was virtually kinematically aligned on 3D bone-cartilage models of healthy knees by using a conventional KA technique (group 1, 36 models, planned KA TKA) or an alternative KA technique (AT KA TKA) aiming to match the proximal (flange area) lateral facet height (10 models, planned AT KA TKA). Also, 13 postoperative bone-implant (KA Persona®) models were co-registered to the same coordinate geometry as their preoperative bone-cartilage models (group 2 - implanted KA TKA). In-house analysis software was used to compare native and prosthetic trochlea articular surfaces and medio-lateral implant overhangs for every group. RESULTS: The planned and performed prosthetic trochleae were similar and valgus oriented (6.1° and 8.5°, respectively), substantially proximally understuffed compared to the native trochlea. The AT KA TKAs shows a high rate of native trochlea surface overstuffing (70%, 90%, and 100% for lateral facet, groove, medial facet) and mediolateral implant overhang (60%). There was no overstuffing with conventional KA TKAs having their anterior femoral cut flush. CONCLUSION: We found that with both the planned and implanted femoral components, the KA Persona® trochlea was more valgus oriented and understuffed compared to the native trochlear anatomy. In addition, restoring the lateral trochlea facet height by increasing t
Rivière C, Dhaif F, Shah H, et al., 2018, Kinematic alignment of current TKA implants does not restore the native trochlear anatomy, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 104, Pages: 673-685, ISSN: 1877-0517
Riviere C, Iranpoura F, Harris S, et al., 2018, Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 104, Pages: 124-130, ISSN: 1877-0517
Riviere C, Iranpour F, Harris S, et al., 2018, Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 104, Pages: 165-170, ISSN: 1877-0568
Rivière C, Iranpour F, Harris S, et al., 2017, The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 103, Pages: 773-777, ISSN: 1877-0517
Rivière C, Iranpour F, Auvinet E, et al., 2017, Mechanical alignment technique for TKA: Are there intrinsic technical limitations?, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 103, Pages: 762-772, ISSN: 1877-0517
Riviere C, Iranpour F, Harris S, et al., 2017, The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 103, Pages: 1069-1073, ISSN: 1877-0568
Rivière C, FarhadIranpour, Auvinet E, et al., 2017, Mechanical Alignment Technique For TKA: Are there Intrinsic Technical Limitations?, Orthopaedics and Traumatology: Surgery and Research, ISSN: 1877-0568
BACKGROUND: Mechanically aligned (MA) total knee arthroplasty (TKA) is affected by disappointing functional outcomes in spite of the recent improvements in surgical precision and implant designs. This might suggest the existence of intrinsic technical limitations. Our study aims to compare the prosthetic and native trochlear articular surfaces and to estimate the extent of collateral ligament imbalance which is technically un-correctable by collateral ligament release when TKA implants are mechanically aligned. STUDY HYPOTHESIS: conventional MA technique generates a high rate of prosthetic overstuffing of the distal groove, distal lateral trochlear facet and distal lateral femoral condyle (Hypothesis 1), and technically un-correctable collateral ligament imbalance (hypothesis 2)? Disregarding the distal femoral joint line obliquity (DFJLO) when performing femoral cuts explainsdistal lateral femoral prosthetic stuffing and un-correctable imbalance (hypothesis 3)? METHODS: Twenty patients underwent a conventional MA TKA. Pre-operative MRI-based 3D knee models were generated and MA TKA was simulated. Native and prosthetic trochlear articular surfaces were compared using in-house analysis software.Following the automatic determination by the planning software of the size of the extension and flexion gaps, an algorithm was applied to balance the gaps and the frequency and amplitude of technically un-correctable knee imbalance wereestimated. RESULTS: The conventional MA technique generateda significant slight distal lateral femoral prosthetic overstuffing (mean 0.6mm, 0.8mm, 1.25 mmfor the most distal lateral facet point, groove, and at the most distal point of lateral femoral condyle, respectively) and a high rate of type 1 and 2 un-corretable knee imbalance (30% and 40%, respectively). The incidence of distal lateral prosthetic overstuffing (trochlea and condyle) and un-correctable knee imbalance were strongly to very strongly correlated with the DFJLO (r=0.53 to 0.89).
Ng CTJ, Newman S, Harris S, et al., 2017, Patient-specific instrumentation improves alignment of lateral unicompartmental knee replacements by novice surgeons., International Orthopaedics, Vol: 41, Pages: 1379-1385, ISSN: 0341-2695
PurposePatient-specific instrumentation (PSI) has the potential to offer numerous benefits—not least of all, improved resection accuracy; but its potential has not been realised in clinical studies. An explanation may be the focus of such studies on the total knee replacement (TKR—a common procedure, with which surgeons are generally very familiar. Consequently, we sought to investigate the potential role of PSI in guiding novice surgeons to perform the more technically demanding and less familiar lateral unicondylar knee replacement (LUKR).MethodsTwelve orthopaedic trainees naive to LUKR were instructed to perform the procedure according to a pre-operative plan. These were carried out on synthetic sawbones and were completed once with conventional instrumentation alone and once with the adjunct of PSI, allowing a comparison of the plan adherence achieved by the two sets of instrumentation.ResultsThere was a tendency for PSI to demonstrate improved plan adherence, though a statistically significant improvement was only seen in compound rotational error of the femoral implant (p = 0.004). PSI was, however, able to produce narrower standard deviations in the mean translational displacement of the femoral implant and also the mean rotational displacement of both implants, suggesting a higher degree of precision.ConclusionsOur study provides some evidence that PSI can improve the ability of novice surgeons to replicate a pre-operative plan, but our results suggest the need for larger-scale clinical studies to establish the role of PSI in this procedure.
Jaffry Z, Masjedi M, Clarke S, et al., 2013, Unicompartmental knee arthroplasties: Robot vs. patient specific instrumentation, The Knee
Masjedi M, Tay C, Harris S, et al., 2013, A Local Reference Frame for Describing the Proximal Human Femur; Application inclinical settings, Skeletal Radiology
Eilander W, Harris SJ, Henkus HE, et al., 2013, Functional acetabular component position with supine total hip replacement, BONE & JOINT JOURNAL, Vol: 95B, Pages: 1326-1331, ISSN: 2049-4394
Masjedi M, Marquardt CS, Drummond IMH, et al., 2012, Cam type femoro-acetabular impingement: quantifying the diagnosis using three dimensional head-neck ratios, Skeletal Radiology, Vol: 42, Pages: 329-33
Masjedi M, Davda K, Harris S, et al., 2012, Mathematical representation of the normal proximal femur – Application in planning of cam hip surgery, Proceedings of the Institution of Mechanical Engineers, Part H, Journal of Engineering in Medicine.
Masjedi M, Azimi D, Nightingale C, et al., 2012, A method of assessing the severity of cam type femoro-acetabular impingement in three dimensions., Hip International., Vol: 22, Pages: 677-82
Cobb JP, Davda K, Ahmad A, et al., 2011, Why large-head metal-on-metal hip replacements are painful THE ANATOMICAL BASIS OF PSOAS IMPINGEMENT ON THE FEMORAL HEAD-NECK JUNCTION, JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 93B, Pages: 881-885, ISSN: 0301-620X
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.
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
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.
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.
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
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.
Davies BL, Harris SJ, Dibble E, 2004, Brachytherapy - an example of a urological minimally invasive robotic procedure, INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Vol: 1, Pages: 88-96, ISSN: 1478-5951
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