Implant orientation accuracy of a hand-held robotic partial knee replacement system over conventional technique in a cadaveric test

Robotic-arm-assisted lateral unicompartmental knee arthroplasty leads to high implant survival and patient satisfaction at mean 10-year follow-up

BACKGROUND

There is a lack of literature reporting on long-term outcomes following robotic-arm-assisted lateral unicompartmental knee arthroplasty (UKA). This study assessed the long-term survivorship, patient-reported satisfaction and pain scores following robotic-arm-assisted lateral UKA for lateral compartment osteoarthritis (OA).

METHODS

A single surgeon's database was reviewed to identify all patients who underwent robotic-arm-assisted lateral UKA with a cemented, fixed-bearing prosthesis prior to May 2015. Patients were contacted to determine implant survivorship, satisfaction and pain. Kaplan-Meier models were applied to analyse survival.

RESULTS

A total of 77 knees (70 patients) with a mean follow-up of 10.2 ± 1.5 years (range: 8.1-13.3) were included. Five knees were revised, corresponding to a 10-year survivorship of 96.1% and estimated survival time of 12.7 ± 0.3 years (95% confidence interval: 12.2-13.2) with all-cause revision as the endpoint. Unexplained pain (40.0%) and progression of OA (40.0%) in contralateral compartments were the most reported reasons for revision. Among patients without revision, 94.4% were either satisfied or very satisfied with their lateral UKA and the average pain score was 1.1.

CONCLUSION

Robotic-arm-assisted lateral UKA led to high implant survivorship and patient satisfaction, and low pain scores at long-term follow-up. Progression of OA in contralateral compartments and unexplained pain were the most frequent reasons for revision. These findings support the continued use of robotic-arm-assisted lateral UKA for lateral compartment OA; however, its clinical value over conventional techniques remains to be established in prospective comparative studies.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Real-time active constraint generation and enforcement for surgical tools using 3D detection and localisation network

Introduction: Collaborative robots, designed to work alongside humans for manipulating end-effectors, greatly benefit from the implementation of active constraints. This process comprises the definition of a boundary, followed by the enforcement of some control algorithm when the robot tooltip interacts with the generated boundary. Contact with the constraint boundary is communicated to the human operator through various potential forms of feedback. In fields like surgical robotics, where patient safety is paramount, implementing active constraints can prevent the robot from interacting with portions of the patient anatomy that shouldn't be operated on. Despite improvements in orthopaedic surgical robots, however, there exists a gap between bulky systems with haptic feedback capabilities and miniaturised systems that only allow for boundary control, where interaction with the active constraint boundary interrupts robot functions. Generally, active constraint generation relies on optical tracking systems and preoperative imaging techniques. Methods: This paper presents a refined version of the Signature Robot, a three degrees-of-freedom, hands-on collaborative system for orthopaedic surgery. Additionally, it presents a method for generating and enforcing active constraints "on-the-fly" using our previously introduced monocular, RGB, camera-based network, SimPS-Net. The network was deployed in real-time for the purpose of boundary definition. This boundary was subsequently used for constraint enforcement testing. The robot was utilised to test two different active constraints: a safe region and a restricted region. Results: The network success rate, defined as the ratio of correct over total object localisation results, was calculated to be 54.7% ± 5.2%. In the safe region case, haptic feedback resisted tooltip manipulation beyond the active constraint boundary, with a mean distance from the boundary of 2.70 mm ± 0.37 mm and a mean exit duration of 0.76 s ± 0.11 s. For the restricted-zone constraint, the operator was successfully prevented from penetrating the boundary in 100% of attempts. Discussion: This paper showcases the viability of the proposed robotic platform and presents promising results of a versatile constraint generation and enforcement pipeline.

Comparison of the radiological parameters between dynamic-referencing tactile guidance robotic system and Microplasty® instrumentation in unicompartmental knee arthroplasty

OBJECTIVES

This study aims to compare the radiological outcomes of unicompartmental knee arthroplasty (UKA) performed by a navigation-based robotic system versus Microplasty® instrumentation.

PATIENTS AND METHODS

Between January 2018 and January 2019, a total of 90 knees of 75 patients (65 males, 10 females; mean age: 62.0±9.4 years; range, 50 to 73 years) were included. Among these, 54 knees underwent Oxford mobile-bearing UKA with an Microplasty® instrumentation set and 36 knees were operated with the aid of a Restoris® MCK with MAKO navigation-based robotic system. Postoperative anteroposterior and lateral X-rays of all patients were evaluated according to nine different parameters. On the femoral side, femoral varus-valgus angle, flexion-extension angle, femoral condyle posterior fit; on tibial side, tibial component varus/valgus, tibial posterior slope, medial, anterior, posterior and lateral fit of tibial component assessed.

RESULTS

There was no significant difference between groups in terms of age, sex, and affected side. On the femoral side, no significant difference was observed in the component position between groups. On the tibial side, tibial component medial fit (p=0.032) and anterior fit (p=0.007) were better in navigation-based robotic system group.

CONCLUSION

Microplasty® instrumentation may lead to comparable implant positioning compared to a tactile-based navigated robotic instrumentation.

Improved accuracy and reproducibility of a novel CT-free robotic surgical assistant for medial unicompartmental knee arthroplasty compared to conventional instrumentation: a cadaveric study

PURPOSE

Alignment errors in medial unicompartmental knee arthroplasty (UKA) predispose to premature implant loosening and polyethylene wear. The purpose of this study was to determine whether a novel CT-free robotic surgical assistant improves the accuracy and reproducibility of bone resections in UKA compared to conventional manual instrumentation.

METHODS

Sixty matched cadaveric limbs received medial UKA with either the ROSA^® Partial Knee System or conventional instrumentation. Fifteen board-certified orthopaedic surgeons with no prior experience with this robotic application performed the procedures with the same implant system. Bone resection angles in the coronal, sagittal and transverse planes were determined using optical navigation while resection depth was obtained using calliper measurements. Group comparison was performed using Student's t test (mean absolute error), F test (variance) and Fisher's exact test (% within a value), with significance at p < 0.05.

RESULTS

Compared to conventional instrumentation, the accuracy of bone resections with CT-free robotic assistance was significantly improved for all bone resection parameters (p < 0.05), other than distal femoral resection depth, which did not differ significantly. Moreover, the variance was significantly lower (i.e. fewer chances of outliers) for five of seven parameters in the robotic group (p < 0.05). All values in the robotic group had a higher percentage of cases within 2° and 3° of the intraoperative plan. No re-cuts of the proximal tibia were required in the robotic group compared with 40% of cases in the conventional group.

CONCLUSION

The ROSA^® Partial Knee System was significantly more accurate, with fewer outliers, compared to conventional instrumentation. The data reported in our current study are comparable to other semiautonomous robotic devices and support the use of this robotic technology for medial UKA.

LEVEL OF EVIDENCE

Cadaveric study, Level V.

Early Economic Analysis of Robotic-Assisted Unicondylar Knee Arthroplasty May Be Cost Effective in Patients with End-Stage Osteoarthritis

Unicondylar knee arthroplasty (UKA), as an alternative to total knee arthroplasty (TKA), has been shown to be an effective option for patients with single-compartment end-stage knee osteoarthritis. Implant survival is contingent upon proper alignment, which has been improved with the advent of robotic-assisted surgery (r-UKA), but whether this outweighs the increased cost of the robotic-assist device has not been analyzed in the literature. The purpose of this study was to investigate the mid-term cost-effectiveness of r-UKA compared with UKA with traditional instrumentation (t-UKA) in the United States. A cost-effectiveness analysis using a four-state Markov model was performed using data from the 2018 National Joint Registry of England and Wales and a retrospective multicenter, cohort study on a cohort of 65-year-old patients having undergone r-UKA. The main outcome was cost per revision avoided and sensitivity analyses were conducted to evaluate the impact of using different model assumptions on the results. The Markov model illustrated that the benefit derived from r-UKA versus t-UKA was beneficial from a payer's perspective. The estimated incremental cost-effectiveness ratio (ICER) was $14,737 per revision avoided in a facility seeing 100 patients a year. Case volume was shown to be the primary variable affecting cost-effectiveness, with the value of r-UKA directly increasing with higher case volumes. Cost-effectiveness analyses demonstrated that the use of r-UKA is an effective alternative to t-UKA in patients with single-compartment knee osteoarthritis. While this study could benefit from longer follow-up clinical studies to illustrate the benefits of r-UKAs beyond the current 2 years time horizon, r-UKAs remained cost-effective, even after investigating several different assumptions.

Optimal designs and surgical technique for hip and knee joint replacement: The best is yet to come!

Over the last three decades, there have been significant advancements in knee and hip replacement technology. The implants and the surgical technology we now have to aid in their implantation are advancing and improving functional outcomes and survivorship. Despite these advancements, there are still issues with patient satisfaction, functional limitations, and early revisions due to instability and aseptic loosening. This article reviews the state of current technology in hip and knee replacement implant design and surgical technique, and reviews some of the current implant designs and surgical technologies that may be able to solve some of the most common issues in the knee and hip replacement surgery.

What is the evidence for clinical use of advanced technology in unicompartmental knee arthroplasty?

BACKGROUND

With an aim of improving prosthesis survivorship of unicompartmental knee arthroplasty (UKA), use of computer-assisted technologies (CATs) such as robotics, has been on the rise to reduce intraoperative errors in surgical technique. In light of recent influx of CATs in the UKA, a review of these innovations will help providers to understand their clinical utility.

METHOD

A systematic literature search was performed following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines.

RESULTS

Among 19 studies comparing robot-assisted UKA with conventional UKA, only 32% were randomized control trials, 47% reported minimum mean follow-up of 2 years, and 21% evaluated prosthesis survival. Similar results were obtained for navigation-assisted UKA and UKA performed with patient-specific instrumentation.

CONCLUSION

While CATs seem to reduce the surgical errors in UKA, the evidence on the efficacy of any of the studied CATs to improve survivorship remains limited and there are issues related to cost-effectiveness, learning curve, and increase in operating time.

External rotation of the tibial component should be avoided in lateral unicompartmental knee arthroplasty

BACKGROUND

Lateral unicompartmental knee arthroplasty (UKA) leads to good clinical outcomes for isolated lateral osteoarthritis. However, the impact of the tibial component position on postoperative outcomes in lateral UKA is yet to be determined.

PURPOSE

This study investigated the influence of tibial component malposition on clinical outcomes in lateral UKA.

MATERIALS

This was a retrospective study of 50 knees (mean age 73.5 years) who underwent lateral UKA between September 2013 and January 2019. The Oxford Knee Score (OKS), Knee Society Score - Knee (KSSK), and Knee Society Score - Function (KSSF) were evaluated. The coronal alignment, posterior slope of tibial component, tibial component rotation relative to Akagi's line (angle α), and femoral anteroposterior (AP) axis (angle β) were measured postoperatively. The average follow up period was 2.3 (range, 1-4.9) years.

RESULTS

Clinical scores were significantly improved after lateral UKA. The mean coronal alignment was 0.9° ± 3.2° varus (range, 9.1° varus to 5.5° valgus), the mean posterior slope was 6.8° ± 3.8° (range, 0.8° to 14.8°). The mean α and β angles, were 4.1° ± 5.8° (range, -9.7° to 16.5°) and 6.7° ± 7.1° (range, -7.0° to 20.5°) external rotation. The angle α had significant negative correlations with postoperative OKS (r = -0.36), KSSK (r = -0.28), and KSSF (r = -0.39), and angle β had significant negative correlations with postoperative OKS (r = -0.34) and KSSK (r = -0.46).

CONCLUSION

Excessive external rotation of the tibial component could negatively influence the postoperative outcomes of lateral UKA.

A systematic review of imageless hand-held robotic-assisted knee arthroplasty: learning curve, accuracy, functional outcome and survivorship

The aim of this systematic review was to present and assess the quality of evidence for learning curve, component positioning, functional outcomes and implant survivorship for image-free hand-held robotic-assisted knee arthroplasty.Searches of PubMed and Google Scholar were performed in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. The criteria for inclusion was any published full-text article or abstract assessing image-free hand-held robotic knee arthroplasty and reporting learning curve, implant positioning, functional outcome or implant survival for clinical or non-clinical studies.There were 22 studies included. Five studies reported the learning curve: all were for unicompartmental knee arthroplasty (UKA) - no learning curve for accuracy, operative time was reduced after five to 10 cases and a steady surgical time was achieved after eight cases.There were 16 studies reporting accuracy: rate of outliers was halved, higher rate of joint line and mechanical axis restoration, supported by low root mean square error values.Six studies reported functional outcome: all for UKA, improvement at six to 52 weeks, no difference from manual UKA except when assessed for lateral UKA which showed improved clinical outcomes.Two studies reported survivorship: one reported an unadjusted revision rate of 7% at 20 months for medial UKA and the other found a 99% two-year survival rate for UKA.There was evidence to support more accurate implant positioning for UKA, but whether this is related to superior functional outcomes or improved implant survivorship was not clear and further studies are required. Cite this article: EFORT Open Rev 2020;5:319-326. DOI: 10.1302/2058-5241.5.190065.