Angus MacLean

Improved Accuracy of Component Positioning with Robotic-Assisted Unicompartmental Knee Arthroplasty: Data from a Prospective, Randomized Controlled Study.

BACKGROUND Higher revision rates have been reported in patients who have undergone unicompartmental knee arthroplasty compared with patients who have undergone total knee arthroplasty, with poor component positioning identified as a factor in implant failure. A robotic-assisted surgical procedure has been proposed as a method of improving the accuracy of component implantation in arthroplasty. The aim of this prospective, randomized, single-blinded, controlled trial was to evaluate the accuracy of component positioning in unicompartmental knee arthroplasty comparing robotic-assisted and conventional implantation techniques. METHODS One hundred and thirty-nine patients were randomly assigned to treatment with either a robotic-assisted surgical procedure using the MAKO Robotic Interactive Orthopaedic Arm (RIO) system or a conventional surgical procedure using the Oxford Phase-3 unicompartmental knee replacement with traditional instrumentation. A postoperative computed tomographic scan was performed at three months to assess the accuracy of the axial, coronal, and sagittal component positioning. RESULTS Data were available for 120 patients, sixty-two who had undergone robotic-assisted unicompartmental knee arthroplasty and fifty-eight who had undergone conventional unicompartmental knee arthroplasty. Intraobserver agreement was good for all measured component parameters. The accuracy of component positioning was improved with the use of the robotic-assisted surgical procedure, with lower root mean square errors and significantly lower median errors in all component parameters (p < 0.01). The proportion of patients with component implantation within 2° of the target position was significantly greater in the group who underwent robotic-assisted unicompartmental knee arthroplasty compared with the group who underwent conventional unicompartmental knee arthroscopy with regard to the femoral component sagittal position (57% compared with 26%, p = 0.0008), femoral component coronal position (70% compared with 28%, p = 0.0001), femoral component axial position (53% compared with 31%, p = 0.0163), tibial component sagittal position (80% compared with 22%, p = 0.0001), and tibial component axial position (48% compared with 19%, p = 0.0009). CONCLUSIONS Robotic-assisted surgical procedures with the use of the MAKO RIO lead to improved accuracy of implant positioning compared with conventional unicompartmental knee arthroplasty surgical techniques. LEVEL OF EVIDENCE Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Improved accuracy of component positioning with robotic assisted unicompartmental knee arthroplasty: data from a prospective, randomised controlled study

BACKGROUND Higher revision rates have been reported in patients who have undergone unicompartmental knee arthroplasty compared with patients who have undergone total knee arthroplasty, with poor component positioning identified as a factor in implant failure. A robotic-assisted surgical procedure has been proposed as a method of improving the accuracy of component implantation in arthroplasty. The aim of this prospective, randomized, single-blinded, controlled trial was to evaluate the accuracy of component positioning in unicompartmental knee arthroplasty comparing robotic-assisted and conventional implantation techniques. METHODS One hundred and thirty-nine patients were randomly assigned to treatment with either a robotic-assisted surgical procedure using the MAKO Robotic Interactive Orthopaedic Arm (RIO) system or a conventional surgical procedure using the Oxford Phase-3 unicompartmental knee replacement with traditional instrumentation. A postoperative computed tomographic scan was performed at three months to assess the accuracy of the axial, coronal, and sagittal component positioning. RESULTS Data were available for 120 patients, sixty-two who had undergone robotic-assisted unicompartmental knee arthroplasty and fifty-eight who had undergone conventional unicompartmental knee arthroplasty. Intraobserver agreement was good for all measured component parameters. The accuracy of component positioning was improved with the use of the robotic-assisted surgical procedure, with lower root mean square errors and significantly lower median errors in all component parameters (p < 0.01). The proportion of patients with component implantation within 2° of the target position was significantly greater in the group who underwent robotic-assisted unicompartmental knee arthroplasty compared with the group who underwent conventional unicompartmental knee arthroscopy with regard to the femoral component sagittal position (57% compared with 26%, p = 0.0008), femoral component coronal position (70% compared with 28%, p = 0.0001), femoral component axial position (53% compared with 31%, p = 0.0163), tibial component sagittal position (80% compared with 22%, p = 0.0001), and tibial component axial position (48% compared with 19%, p = 0.0009). CONCLUSIONS Robotic-assisted surgical procedures with the use of the MAKO RIO lead to improved accuracy of implant positioning compared with conventional unicompartmental knee arthroplasty surgical techniques. LEVEL OF EVIDENCE Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Diagnostic accuracy of the Thessaly test, standardised clinical history and other clinical examination tests (Apley’s, McMurray’s and joint line tenderness) for meniscal tears in comparison with magnetic resonance imaging diagnosis

BACKGROUND Reliable non-invasive diagnosis of meniscal tears is difficult. Magnetic resonance imaging (MRI) is often used but is expensive and incidental findings are problematic. There are a number of physical examination tests for the diagnosis of meniscal tears that are simple, cheap and non-invasive. OBJECTIVES To determine the diagnostic accuracy of the Thessaly test and to determine if the Thessaly test (alone or in combination with other physical tests) can obviate the need for further investigation by MRI or arthroscopy for patients with a suspected meniscal tear. DESIGN Single-centre prospective diagnostic accuracy study. SETTING Although the study was performed in a secondary care setting, it was designed to replicate the results that would have been achieved in a primary care setting. PARTICIPANTS Two cohorts of patients were recruited: patients with knee pathology (n = 292) and a control cohort with no knee pathology (n = 75). MAIN OUTCOME MEASURES Sensitivity, specificity and diagnostic accuracy of the Thessaly test in determining the presence of meniscal tears. METHODS Participants were assessed by both a primary care clinician and a musculoskeletal clinician. Both clinicians performed the Thessaly test, McMurrays test, Apleys test, joint line tenderness test and took a standardised clinical history from the patient. RESULTS The Thessaly test had a sensitivity of 0.66, a specificity of 0.39 and a diagnostic accuracy of 54% when utilised by primary care clinicians. This compared with a sensitivity of 0.62, a specificity of 0.55 and diagnostic accuracy of 59% when used by musculoskeletal clinicians. The diagnostics accuracy of the other tests when used by primary care clinicians was 54% for McMurrays test, 53% for Apleys test, 54% for the joint line tenderness test and 55% for clinical history. For primary care clinicians, age and past history of osteoarthritis were both significant predictors of MRI diagnosis of meniscal tears. For musculoskeletal clinicians age and a positive diagnosis of meniscal tears on clinical history taking were significant predictors of MRI diagnosis. No physical tests were significant predictors of MRI diagnosis in our multivariate models. The specificity of MRI diagnosis was tested in subgroup of patients who went on to have a knee arthroscopy and was found to be low [0.53 (95% confidence interval 0.28 to 0.77)], although the sensitivity was 1.0. CONCLUSIONS The Thessaly test was no better at diagnosing meniscal tears than other established physical tests. The sensitivity, specificity and diagnostic accuracy of all physical tests was too low to be of routine clinical value as an alternative to MRI. Caution needs to be exercised in the indiscriminate use of MRI scanning in the identification of meniscal tears in the diagnosis of the painful knee, due to the low specificity seen in the presence of concomitant knee pathology. Further research is required to determine the true diagnostic accuracy and cost-effectiveness of MRI for the detection of meniscal tears. TRIAL REGISTRATION Current Controlled Trial ISRCTN43527822. FUNDING The National Institute for Health Research Health Technology Assessment programme.

Robotic-arm assisted versus conventional unicompartmental knee arthroplasty: exploratory secondary analysis of a Randomised Controlled Trial

Objectives This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group. Methods A total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery. Results From the first post-operative day through to week 8 post-operatively, the median pain scores for the robotic arm-assisted group were 55.4% lower than those observed in the manual surgery group (p = 0.040). At three months post-operatively, the robotic arm-assisted group had better AKSS (robotic median 164, interquartile range (IQR) 131 to 178, manual median 143, IQR 132 to 166), although no difference was noted with the OKS. At one year post-operatively, the observed differences with the AKSS had narrowed from a median of 21 points to a median of seven points (p = 0.106) (robotic median 171, IQR 153 to 179; manual median 164, IQR 144 to 182). No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43). A greater proportion of patients receiving robotic arm-assisted surgery improved their UCLA activity score. Binary logistic regression modelling for dichotomised outcome scores predicted the key factors associated with achieving excellent outcome on the AKSS: a pre-operative activity level > 5 on the UCLA activity score and use of robotic-arm surgery. For the same regression modelling, factors associated with a poor outcome were manual surgery and pre-operative depression. Conclusion Robotic arm-assisted surgery results in improved early pain scores and early function scores in some patient-reported outcomes measures, but no difference was observed at one year post-operatively. Although improved results favoured the robotic arm-assisted group in active patients (i.e. UCLA ⩾ 5), these do not withstand adjustment for multiple comparisons. Cite this article: M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. MacLean, B. Jones. Robotic arm-assisted versus conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. Bone Joint Res 2017;6:631–639. DOI: 10.1302/2046-3758.611.BJR-2017-0060.R1.

A comparison of gait one year post operation in an RCT of robotic UKA versus traditional Oxford UKA

Robot-assisted unicompartmental knee surgery has been shown to improve the accuracy of implant alignment. However, little research has been conducted to ascertain if this results in a measureable improvement in knee function post operatively and a more normal gait. The kinematics of 70 OA knees were assessed using motion analysis in an RCT (31 receiving robotic-assisted surgery, and 39 receiving traditional manual surgery) and compared to healthy knees. Statistically significant kinematic differences were seen between the two surgical groups from foot-strike to mid-stance. The robotic-assisted group achieved a higher knee excursion (18.0°, SD 4.9°) compared to the manual group (15.7°, SD 4.1°). There were no significant difference between the healthy group and the robotic assisted group, however there was a significant difference between the healthy group and the manual group (p < 0.001). Hence robotically-assisted knee replacement with Mako Restoris Implants appears to lead not only to better implant alignment but also some kinematic benefits to the user during gait.

Robotic-arm-assisted vs conventional unicompartmental knee arthroplasty. The 2-year clinical outcomes of a randomized controlled trial

BACKGROUND Unicompartmental knee arthroplasty (UKA) for treatment of medial compartment osteoarthritis has potential benefits over total knee arthroplasty but UKA has a higher revision rate. Robotic-assisted UKA is increasingly common and offers more accurate implant positioning and limb alignment, lower early postoperative pain but evidence of functional outcome is lacking. The aim was to assess the clinical outcomes of a single-centre, prospective, randomised controlled trial, comparing robotic-arm-assisted UKA with conventional surgery. METHODS A total of 139 participants were recruited and underwent robotic-arm-assisted (fixed bearing) or conventional (mobile bearing) UKA. Fifty-eight patients in the robotic-arm-assisted group and 54 in the manual group at 2 years. The main outcome measures were the Oxford Knee Score, American Knee Society Score and revision rate. RESULTS At 2 years, there were no significant differences for any of the outcome measures. Sub-group analysis (n = 35) of participants with a preoperative University of California Los Angeles Activity Scale >5 (more active) was performed. In this sub-group, the median Oxford Knee Score at 2 years was 46 (IQR 42.0-48.0) for robotic-arm-assisted and 41 (IQR 38.5-44.0) for the manual group (P = .036). The median American Knee Society Score was 193.5 (IQR 184.0-198.0) for the robotic-arm-assisted group and 174.0 (IQR 166.0-188.5) for the manual group (P = .017). Survivorship was 100% in robotic-arm-assisted group and 96.3% in the manual group. CONCLUSION Overall, participants achieved an outcome equivalent to the most widely implanted UKA in the United Kingdom. Sub-group analysis suggests that more active patients may benefit from robotic-arm- assisted surgery. Long term follow-up is required to evaluate differences in survivorship.

O 017 - A five-year follow up of gait in robotic assisted vs conventional unicompartmental knee arthroplasty

Recently, systems have been developed to improve alignment of unicompartmental knee arthroplasty (UKA) implants, although improvement in function has been difficult to document. The MAKO RIO robotic surgery system has previously shown improvements in in knee flexion during weight acceptance (WA) in comparison to conventional methods at a one year follow up. This study aimed to determine if these improvements remained at five years follow up. Twenty five MAKO and 21 conventional knees were tested using three dimensional gait analysis to measure knee kinematics. Results demonstrated that the MAKO group achieved significantly greater knee flexion in WA than the conventional group which was consistent with results are one year. This could be due to the improved accuracy of prosthesis implantation offered by the MAKO system.