Imageless robotic-assisted total knee arthroplasty is accurate in vivo: a retrospective study to measure the postoperative bone resection and alignment

Sagittal accuracy and functional impact of tibial slope in imageless robotic-assisted Total Knee Arthroplasty

PURPOSE

Study of the sagittal accuracy of the 'Robotic Surgical Assistant' (ROSA®), compared to conventional surgery, regarding the application of the tibial slope (TS). Study of the impact of TS on the range of motion (ROM) and patient-reported outcome measures (PROMS).

METHODS

Inclusion of patients who underwent primary Total Knee Arthroplasty (TKA) between 1/1/2021 and 15/4/2024. Divided into robotic-assisted TKA (RA-TKA) and manual TKA (M-TKA). Measurement of pre- and post-operative TS, using the posterior tibial cortex, on profile knee X-rays. 3° TS applied arbitrarily for both groups. ROM was measured pre-operatively and at three, six and 12 months post-operatively. Patient satisfaction assessed via Knee Injury and Osteoarthritis Outcome Score (KOOS) and Oxford Knee Score (OKS).

RESULTS

266 patients were included in the study. The M-TKA (110) had a post-operative TS of 3.11° (± 2.12°). 81.21% were within 2° of the target and 92.87% within 3°. The RA-TKA (82) had a post-operative TS of -0.11° ± (1.93°). 36.83% were within 2° of the target and 56.63% within 3°. RA-TKA had a KOOS of 64.43 ± 12.87 and OKS of 33.05 ± 6.01. M-TKA had a KOOS of 64.18 ± 13.11 and OKS of 32.31 ± 5.97. Maximum flexion at 12 months was 118.74° ± 8.19° for M-TKA and 121.88° ± 7.43° for RA-TKA (p = 0.002).

CONCLUSION

The application of TS using ROSA® was less precise than the conventional method in achieving post-operative TS values as measured on X-rays. However, there were no clinical differences in ROM or PROMS.

Improved Efficiency and Intraoperative Planning With 1 Robot-Assisted Total Knee Arthroplasty System

Background

Robotic-assisted total knee arthroplasty (rTKA) has garnered significant interest for its potential to enhance surgical precision and accuracy. However, the adoption of such systems poses concerns, including longer operative times and learning curves, potentially reducing efficiency. This study aimed to evaluate the learning curve associated with the Robotic Surgical Assistant (ROSA) system for rTKA.

Methods

This retrospective review analyzed the first 75 ROSA rTKA procedures performed by each of 2 fellowship-trained arthroplasty surgeons (150 total procedures) at a high-volume institution. Time stamps within the robotic software were recorded for each case, along with tourniquet time. Statistical analyses included descriptive statistics, t-tests, and multilevel regression.

Results

Comparison of each surgeon's first 20 and last 20 cases revealed significant decreases in tourniquet time (61.4-56.7 minutes; P = .0417) and planning time (13.49-6.68 minutes; P = .0078). Landmark femur and tibia times remained stable (P = .6542 and P = .9440). Knee state evaluation time showed a trend of reduction from 9.22 to 7.33 minutes (P = .1335), and resection time from 13.66 to 12.92 minutes (P = .4372). Regression analysis indicated significant reductions in tourniquet time (β = -0.11; P = .0089) and planning time (β = -0.08; P = .0064).

Conclusions

This study demonstrates that execution of ROSA rTKA becomes more efficient over the first 75 cases. The greatest improvement with experience is the time spent on the planning panel, the cognitive portion of the procedure. These data provide surgeons with the confidence that the technical portions of the case are quick to learn and guide industry to focus on teaching effective adjustments on the planning panel.

Does robotic surgical assistant (ROSA) functionally aligned TKA lead to higher satisfaction than conventional mechanically aligned TKA: A propensity-matched pair analysis

Objectives

Total knee arthroplasty (TKA) is the established treatment for severe knee osteoarthritis, with robotic-assisted TKA (rTKA) proposed to enhance surgical precision and potentially improve outcomes. This study investigates whether functionally-aligned rTKA using the ROSA Knee System results in superior functional outcomes and patient satisfaction compared to conventional mechanically aligned TKA (mTKA).

Methods

We conducted a retrospective, propensity-score matched cohort study including 154 patients (46 rTKA, 108 mTKA) who underwent primary TKA by a single surgeon from October 2020 to October 2023. Functionally-aligned (FA) rTKA was performed using the ROSA Knee System. Patients were assessed using the Short-Form 36 (SF36), Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), and Oxford Knee Score (OKS) preoperatively and at 6 months postoperatively. Immediate postoperative outcomes such as pain at rest and movement, ambulation distance, and range of motion were measured. Statistical analysis evaluated results at a 95 % confidence interval, with significance at P < 0.05.

Results

No significant differences were observed in immediate postoperative pain at rest (P = 0.988), pain during movement (P = 0.634), ambulation distance (P = 0.243), and range of motion (P = 0.752) between the groups. At 6 months, there were no significant differences between rTKA and mTKA in achieving the minimal clinically important difference for SF36 (P = 0.996), KSKS (P = 0.150), KSFS (P = 0.091), and OKS (P = 0.949). No significant differences were noted for satisfaction levels (P = 0.315) and fulfilled expectations (P = 0.557) between both groups.

Conclusions

At 6 months postoperatively, FA rTKA demonstrated equivalent outcomes and satisfaction levels compared to mTKA. Future research should focus on examining longer-term follow-up outcomes, quantifying gap balance in MA mTKA to allow direct comparison with rTKA and studying alternative personalised alignment rTKA strategies to enhance patient outcomes.

Handheld imageless robotic total knee arthroplasty improves accuracy and early clinical outcomes when compared with navigation

BACKGROUND

This study compared imageless robotic-assisted total knee arthroplasty (RATKA) with accelerometer-based navigation (ABN) systems in terms of surgical accuracy and early clinical outcomes.

METHODS

A retrospective analysis was conducted on 153 patients (178 knees) who had undergone primary TKA from 2017 to 2023. Surgical accuracy and functional outcomes were assessed up to 12 months post-operation using the Chi-square test, Student's t-test, and ANCOVA. Subgroup analyses based on patient demographics were also conducted.

RESULTS

Among 153 patients, 101 underwent RATKA, and 52 received ABN. RATKA demonstrated superior alignment accuracy with a significantly lower deviation from the planned alignment (P < 0.05). Additionally, RATKA led to significantly better postoperative functional scores at 6 weeks (P = 0.001) and 3 months (P = 0.001), even after adjusting for preoperative functional differences.

CONCLUSIONS

RATKA offers enhanced precision and improves early recovery compared to ABN, supporting its potential as a preferred technology for TKA. Its ability to optimize kinematic alignment may contribute to superior patient outcomes. Compared to ABN, RATKA provides a unique advantage by achieving greater accuracy in planned alignment, which may translate into improved functional recovery. Further research with larger cohorts is recommended to confirm these findings.

Femoral resection accuracy and precision in manual caliper-verified kinematic alignment total knee arthroplasty

Introduction

The accuracy and precision of bone resections in total knee arthroplasty (TKA) are essential to avoid poor implant positioning, which can lead to component wear, pain, and instability, reducing patient satisfaction and implant survivorship. Technology-assisted TKA techniques aim to improve accuracy but come with added costs, increased operative time, and varying success in clinical outcomes. Caliper-verified kinematic alignment (KA) attempts to restore the joint line by precisely measuring resections to equal implant thickness. We evaluated the accuracy and precision of caliper-verified KA-TKA performed with manual instruments. We hypothesised that this technique would achieve high accuracy and precision, with an average absolute difference between actual and target distal and posterior femoral resection measurements of ≤ 0.5 mm.

Methods

385 consecutive patients underwent primary unrestricted caliper-verified KA-TKA with manual instrumentation. The thickness of the distal medial (DM), distal lateral (DL), posterior medial (PM) and posterior lateral (PL) femoral condyle resections were measured with a caliper and compared to a target determined by the degree of cartilage loss, saw blade kerf, and femoral component thickness.

Results

The mean differences between the resected and target thicknesses for DM, DL, PM and PL femoral resections were 0.1 ± 0.2 mm, 0.1 ± 0.3 mm, 0.3 ± 0.5 mm and 0.2 ± 0.4 mm, respectively (mean ± std. dev.). Most femoral resections were within 0.5 mm of the target-97.7%, 94.5%, 85.7% and 89.4% of DM, DL, PM and PL resections, respectively.

Conclusion

Manual caliper-verified KA-TKA achieved highly accurate and precise femoral resections with absolute differences from target that averaged 0.175 mm. This simple, logical, efficient, and reproducible surgical technique may be an option for surgeons contemplating the use of technology-assisted options, such as patient-specific instrumentation or robotic arm-assisted TKA, and surgeons without access to such technologies.

Level of Evidence

Level II.

Robotic-Assisted Primary Total Knee Arthroplasty Requires Fewer Soft-Tissue Releases and Is Associated With a Larger Reduction in Early Postoperative Pain

BACKGROUND

Robotic-assisted total knee arthroplasty (RATKA) has been shown to improve the accuracy of component alignment and to potentially reduce the need for soft-tissue releases. To date, however, the potential benefits of expedited recovery, improved functional outcomes, and improved longevity of RATKA remain unproven. The purpose of this study was to compare functional outcomes and rates of soft-tissue releases between RATKA, conventional instrumentation (CONV), and accelerometer-based navigation (ABN) in primary total knee arthroplasties (TKAs).

METHODS

A retrospective study of 2,338 consecutive TKAs performed by two surgeons was performed. There were 1,216 TKAs performed with CONV and the goal of neutral mechanical alignment. There were 724 TKAs performed with ABN and restricted kinematic alignment goals. There were 398 RATKAs performed with a functional alignment philosophy. Radiographs were reviewed for all knees. We compared Patient-Reported Outcomes Measurement Information System scores (2 weeks, 6 weeks, and 1 year) and rates of soft-tissue releases between ABN and RATKA cohorts. Chi-square tests were used to compare rates of releases between cohorts. Generalized estimating equations were used to evaluate outcomes over time.

RESULTS

Overall, the rate of soft-tissue releases was 47.9% in CONV, 74.4% in the ABN group, and 29.9% in the RATKA group. The RATKAs required significantly fewer medial releases in varus knees than CONV (19.9 versus 46.3%, P < 0.001) and ABN TKAs (19.9 versus 68.8%, P < 0.001). In valgus knees, RATKAs required significantly fewer lateral releases than CONV (33.7 versus 61.6%, P < 0.001) and ABN TKAs (33.7 versus 46.6%, P < 0.001). The RATKA had a greater reduction in pain scores (mean 4.5 more points) than the ABN cohort from preoperative to 6 weeks (P = 0.038) with no difference in pain scores beyond 6 weeks. There were no differences in Patient-Reported Outcomes Measurement Information System scores at 1-year follow-up.

CONCLUSIONS

In this series, RATKA with a functional alignment goal performed by adjusting component placement and bony cuts to balance the knee resulted in fewer soft-tissue releases when compared to conventional instrumented TKA and navigated TKA. The RATKAs also demonstrated a larger reduction in short-term pain scores when compared to ABN TKAs, but no differences in patient-reported outcome scores at 1 year.

Image-based robotic (ROSA® knee system) total knee arthroplasty with inverse kinematic alignment compared to conventional total knee arthroplasty : Study protocol and the inverse kinematic alignment in 8-steps using the ROSA® Knee system for knee balancing technique explained

INTRODUCTION

In 2020, 368 million people globally were affected by knee osteoarthritis, and prevalence is projected to increase with 74% by 2050. Relatively high rates of dissatisfactory results after total knee arthroplasty (TKA), as reported by approximately 20% of patients, may be caused by sub-optimal knee alignment and balancing. While mechanical alignment has traditionally been the goal, patient-specific alignment strategies are gaining interest. Robotic assistance could potentially facilitate implementation of these alignment strategies through data-based surgical planning, accurate execution of the surgical plan and validation. The clinical value of surgical assistance in diverging from mechanical alignment remains to be investigated. In the present study, robotic-assisted TKA will be performed to pursue inverse kinematic alignment (iKA) within predefined boundaries, focusing on restoring native tibia joint line.

METHODS

This randomized controlled trial evaluates clinical effectiveness of robotic-assisted TKA (ROSA® Knee System, Zimmer Biomet, Montreal, Quebec, Canada) aiming for iKA compared to conventional TKA aiming for mechanical alignment. A total of 150 participants will be randomized (1:1) to either treatment to provide an 80% power for a 4.8-point clinically important difference in the primary outcome measure, the Oxford Knee Score (OKS) 12 months after surgery. Allocation was achieved using computer-based randomization. Outcomes will be analyzed using linear mixed models with time and group as main factors and interaction-term. Secondary outcomes include clinical metrics (leg alignment, implant and patient survival), surgical parameters (adverse events, surgery duration, blood loss, hospital stay length, medication use), patient-reported outcomes (symptoms, quality of life, pain), mobility and physical activity measurements, metabolic syndrome, cost-efficacy, and gait and continuous glucose monitoring.

ETHICS AND DISSEMINATION

This study has been approved by the Medical Ethical Committee Zuyd and Zuyderland Medical Centre (NL79161.096.21/METCZ20220006), September 2022.

TRIAL REGISTRATION NUMBER

NCT05685693 (clinicaltrials.gov).

Novel application of an imageless robotic system in simultaneous unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction

This technical note explores the novel use of an imageless robotic surgical system for simultaneous unicompartmental knee arthroplasty (UKA) and anterior cruciate ligament reconstruction (ACLR). Knee osteoarthritis (OA) and anterior cruciate ligament (ACL) insufficiency are common conditions that traditionally require separate management. The integration of robotic assistance offers enhanced precision in surgical procedures, addressing both medial compartment OA and ACL insufficiency in a single operation. We present a case involving a 47-year-old patient with medial compartment osteoarthritis and complete ACL rupture. The patient underwent a simultaneous robotic-assisted UKA and ACLR using the CORI Surgical System (Smith&Nephew, London, UK). This approach enables accurate tibial tunnel placement and precise soft tissue balancing. The robotic system facilitates real-time gap assessment and balancing, reducing the risk of over- or under-constraint during ACL graft tensioning. The procedure was performed with a standard medial parapatellar approach. Key steps included hamstring autograft harvesting, femoral and tibial tunnel creation, and robotic-assisted implant positioning. Post-operative rehabilitation allowed full weight-bearing by the third week. This case represents the first reported instance of using an imageless robotic system for simultaneous UKA and ACLR, highlighting its potential to standardize and improve results in complex knee surgeries. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

High in-vivo accuracy of a novel robotic-arm-assisted system for total knee arthroplasty

PURPOSE

Robotic-assisted total knee arthroplasty (TKA) has been shown to improve the accuracy and precision of bony resections and implant position. However, the in vivo accuracy of the full surgical workflow has not been widely reported. The primary objective of this study is to determine the accuracy and precision of a robotic-arm-assisted system throughout the intraoperative workflow.

METHODS

This was a retrospective cohort study of adult patients who underwent primary TKA with various workflows and alignment targets by three arthroplasty-trained surgeons with previous experience using the ROSA® Knee System (Zimmer Biomet) over a 3-month follow-up period. Accuracy and precision were determined by measuring the difference between various workflow time points, including the final preoperative plan (PP), robot-validated (RV) resection angle and postoperative radiographs (PR). The absolute mean difference between the measurements determined accuracy, and the standard deviation represented precision. The lateral distal femoral angle, medial proximal tibial angle, femoral flexion angle and tibial slope were measured on postoperative coronal long-leg radiographs and true short-leg lateral radiographs.

RESULTS

A total of 77 patients were included in the final analyses. The accuracy for the coronal femoral angle was 1.62 ± 1.11°, 0.75 ± 0.79° and 1.96 ± 1.29° for the differences between PP and PR, PP and RV and RV and PR. The tibial coronal accuracy was 1.44 ± 1.03°, 0.81 ± 0.67° and 1.57 ± 1.14° for PP/PR, PP/RV and RV/PR, respectively. Femoral flexion accuracy was 1.39 ± 1.05°, 0.83 ± 0.59° and 1.81 ± 1.21° for PP/PR, PP/RV and RV/PR, respectively. Tibial slope accuracy was 0.99 ± 0.72°, 1.19 ± 0.87° and 1.63 ± 1.11°, respectively. The proportion of patients within 3° was 93.2%, 95.3%, 97.3% and 94.6% for the distal femur, proximal tibia, femoral flexion and tibial slope angles when the final intraoperative plan was compared to PRs. No patients had a postoperative complication at the final follow-up.

CONCLUSIONS

The ROSA Knee System has acceptable accuracy and precision of coronal and sagittal plane resections with few outliers at various steps throughout the platform's entire workflow in vivo.

LEVEL OF EVIDENCE

Level III.

Accuracy and Outcomes of a Novel Cut-Block Positioning Robotic-Arm Assisted System for Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Background

The primary objective of this study was to determine the accuracy and precision of component positioning of the ROSA Robotic System for total knee arthroplasty (TKA).

Methods

A Preferred Reporting Items for Systematic Reviews and Meta-Analysis systematic review was conducted using 4 electronic databases (MEDLINE, EMBASE, Pubmed, and Cochrane Library) to identify all clinical and radiological studies reporting information about the use and results of the ROSA system. The criteria for inclusion were published research articles evaluating the accuracy of component positioning, learning curve, component alignment, complications, and functional outcomes in adults who underwent robotic-assisted TKA. The National Institutes of Health Quality Assessment Tool was used to evaluate the quality of all the included studies.

Results

A total of 26 studies were assessed for eligibility, and 17 met the inclusion criteria. Nine studies reported on the accuracy and precision of component positioning. The ROSA platform for TKA had a cutting error of less than 0.6° for all coronal and sagittal parameters. Pooled analysis demonstrated accuracy within 0.61-1.87° and precision within 0.97-1.34° when the final intraoperative plan was compared to postoperative radiographs with fewer outliers. Four studies reported improved functional scores with ROSA-assisted TKA than conventional TKA within 1 year of surgery. There was no difference in overall complication rates when compared to conventional TKA.

Conclusions

The ROSA system is both highly accurate and precise, with fewer outliers when analyzed at various time points, including postoperative standing radiographs. Future studies with robust methodology and longer follow-up are required to demonstrate whether these findings have any clinical benefits in the long term.

Robotic Total Knee Arthroplasty: An Update

Total knee arthroplasty (TKA) is a gold standard surgical procedure to improve pain and restore function in patients affected by moderate-to-severe severe gonarthrosis refractory to conservative treatments. Indeed, millions of these procedures are conducted yearly worldwide, with their number expected to increase in an ageing and more demanding population. Despite the progress that has been made in optimizing surgical techniques, prosthetic designs, and durability, up to 20% of patients are dissatisfied by the procedure or still report knee pain. From this perspective, the introduction of robotic TKA (R-TKA) in the late 1990s represented a valuable instrument in performing more accurate bone cuts and improving clinical outcomes. On the other hand, prolonged operative time, increased complications, and high costs of the devices slow down the diffusion of R-TKA. The advent of newer technological devices, including those using navigation systems, has made robotic surgery in the operatory room more common since the last decade. At present, many different robots are available, representing promising solutions to avoid persistent knee pain after TKA. We hereby describe their functionality, analyze potential benefits, and hint at future perspectives in this promising field.

Robotic-assisted total knee arthroplasty is not associated with improved accuracy in implant position and alignment compared to conventional instrumentation in the execution of a preoperative digital plan

Purpose

The primary objective of the present study was to evaluate if robotic-assisted total knee arthroplasty (RO-TKA) results in improved accuracy compared to conventional TKA (CO-TKA) with respect to alignment and component positioning executing a preoperative digital plan. The secondary objective was to compare patient-reported outcome measures (PROMs) between the two groups at 6 months of follow-up (FU).

Methods

Patients who underwent primary TKA using the concept of constitutional alignment were identified from the database. Each patient underwent preoperative digital planning as well as postoperative evaluation of the preoperative plan (alignment and component position) using mediCAD® software (Hectec GmbH). Two groups were formed: (i) The RO-TKA group (n = 30) consisted of patients who underwent TKA with a robotic surgical system (ROSA®, Zimmer Biomet) and (ii) the CO-TKA group (n = 67) consisted of patients who underwent TKA with conventional instrumentation. To assess accuracy, all qualitative variables were analysed using the χ 2 test. Tegner activity scale, Oxford Knee Score and visual analogue scale were assessed preop and at 6-month FU. To assess differences between the two groups, a 2 × 2 repeated measures analysis of variance was performed.

Results

There was no significant (p > 0.05) difference in the accuracy of alignment as well as tibial and femoral component position between the two groups. At the 6-month FU, there was no significant (p > 0.05) difference in PROMs between the two groups.

Conclusion

While robotic TKA may have some potential advantages, no significant difference was found between robotic and conventional TKA with respect to limb alignment, clinical outcomes and component positioning.

Level of Evidence

Level III.