Robotic-Assisted Unicompartmental Knee Arthroplasty: State-of-the Art and Review of the Literature

Insights into complications after unicompartmental knee arthroplasty

Zhao's study, offers a comprehensive analysis of unicompartmental knee arthroplasty (UKA) revision indications. The study provides a detailed, case-by-case analysis of the factors leading to knee revision surgery in 13 patients. Not only elucidates the complexities of UKA revisions but also underscores the importance of continuous improvement in surgical techniques and the adoption of innovative technologies.

Challenges in Residual Bearing Removal: A Rare Case of Mobile Bearing Fracture in Unicompartmental Knee Arthroplasty with Literature Review

BACKGROUND

Mobile bearing fracture is a rare long-term complication of unicompartmental knee arthroplasty (UKA), and relevant reports are sparse. Hence, its treatment options need further exploration.

CASE PRESENTATION

This study presents the case of fracture of a polyethylene insert that occurred 12 years after mobile bearing medial UKA in a 75-year-old overweight woman who then underwent surgical intervention at our institution. However, we encountered significant challenges in removing the fragments from the broken bearing, resulting in retention of the remaining one-third of the fragment. We solved this problem by replacing the fractured insert with thicker mobile bearing. During the 1-month postoperative follow-up, the patient achieved good range of motion and excellent satisfaction, with no reported complications and a Knee Society Score of 90. Additionally, we reviewed the literature on the treatment for mobile bearing fractures after UKA.

CONCLUSIONS

Bearing fracture is a rare cause of failure of mobile bearing UKA. This case highlights the challenges of UKA fracture bearing retrieval and underscores that mobile bearing replacement can be an effective intervention. The case we report shows that when removal of a residual meniscal bearing in a posterior dislocation is difficult to achieve, compromise may be an appropriate option because it does not cause additional complaints to the patient. This case emphasizes the importance of the surgeon having a thorough preoperative understanding of the location and potential pitfalls of fracture fragments in such situations.

Reducing edge loading and alignment outliers with image-free robotic-assisted unicompartmental knee arthroplasty: a case controlled study

BACKGROUND

Survivorship of medial unicompartmental knee arthroplasty (UKA) is technique-dependent. Correct femoral-tibial component positioning associates with improved survivorship. Image-free robotic-assisted unicompartmental knee arthroplasty enables preoperative and intraoperative planning of alignment and assessment of positioning prior to execution. This study aimed to compare the radiological outcomes between robotic-assisted UKA (R-UKA) and conventional UKA (C-UKA).

METHODS

This retrospective case control study involved 140 UKA (82 C-UKA and 58 R-UKA) performed at an academic institution between March 2016 to November 2020, with a mean follow-up of 3 years. Postoperative radiographs were evaluated for mechanical axis and femoral-tibial component position. Component position was measured by two methods: (1) femoral-tibial component contact point with reference to four medial-to-lateral quadrants of the tibial tray and (2) femoral-tibial component contact point deviation from the center of the tibial tray as a percentage of the tibial tray width. Baseline demographics and complications were recorded.

RESULTS

There was a higher mean component deviation in C-UKA compared with R-UKA using method 2 (17.2% vs. 12.8%; P = 0.007), but no difference in proportion of zonal outliers using method 1 (4 outliers in C-UKA, 5.1% vs. 1 outlier in R-UKA, 1.8%; P = 0.403). R-UKA showed no difference in mean mechanical alignment (C-UKA 5° vs. R-UKA 5°; P = 0.250). 2-year survivorship was 99% for C-UKA and 97% for R-UKA. Mean operative time was 18 min longer for R-UKA (P < 0.001).

CONCLUSION

Image-free robotic-assisted UKA had improved component medio-lateral alignment compared with conventional technique.

Subchondral bone expansion in advanced knee osteoarthritis: Relation with radiographic severity and role in surgical decision-making

Background

Joint space width (JSW) is a traditional imaging marker for knee osteoarthritis (OA) severity, but it lacks sensitivity in advanced cases. We propose tibial subchondral bone area (TSBA), a new CT imaging marker to explore its relationship with OA radiographic severity, and to test its performance for classifying surgical decisions between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) compared to JSW.

Methods

We collected clinical, radiograph, and CT data from 182 patients who underwent primary knee arthroplasty (73 UKA, 109 TKA). The radiographic severity was scored using Kellgren-Lawrence (KL) grading system. TSBA and JSW were extracted from 3D CT-reconstruction model. We used independent t-test to investigate the relationship between TSBA and KL grade, and binary logistic regression to identify factors associated with TKA risk. The accuracy of TSBA, JSW and established classification model in differentiating between UKA and TKA was assessed using AUC.

Results

All parameters exhibited inter- and intra-class coefficients greater than 0.966. Patients with KL grade 4 had significantly larger TSBA than those with KL grade 3. TSBA (0.708 of AUC) was superior to minimal/average JSW (0.547/0.554 of AUC) associated with the risk of receiving TKA. Medial TSBA, together with gender and Knee Society Knee Score, emerged as independent classification factors in multivariate analysis. The overall AUC of composite model for surgical decision-making was 0.822.

Conclusion

Tibial subchondral bone area is an independent imaging marker for radiographic severity, and is superior to JSW for surgical decision-making between UKA and TKA in advanced OA patients.

Robotic-assisted unicompartmental knee arthroplasty improves functional outcomes, complications, and revisions

Aims

Robotic-assisted unicompartmental knee arthroplasty (R-UKA) has been proposed as an approach to improve the results of the conventional manual UKA (C-UKA). The aim of this meta-analysis was to analyze the studies comparing R-UKA and C-UKA in terms of clinical outcomes, radiological results, operating time, complications, and revisions.

Methods

The literature search was conducted on three databases (PubMed, Cochrane, and Web of Science) on 20 February 2024 according to the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Inclusion criteria were comparative studies, written in the English language, with no time limitations, on the comparison of R-UKA and C-UKA. The quality of each article was assessed using the Downs and Black Checklist for Measuring Quality.

Results

Among the 3,669 articles retrieved, 21 studies on 19 series of patients were included. A total of 3,074 patients (59.5% female and 40.5% male; mean age 65.2 years (SD 3.9); mean BMI 27.4 kg/m2 (SD 2.2)) were analyzed. R-UKA obtained a superior Knee Society Score improvement compared to C-UKA (mean difference (MD) 4.9; p < 0.001) and better Forgotten Joint Score postoperative values (MD 5.5; p = 0.032). The analysis of radiological outcomes did not find a statistically significant difference between the two approaches. R-UKA showed longer operating time (MD 15.6; p < 0.001), but reduced complication and revision rates compared to C-UKA (5.2% vs 10.1% and 4.1% vs 7.2%, respectively).

Conclusion

This meta-analysis showed that the robotic approach for UKA provided a significant improvement in functional outcomes compared to the conventional manual technique. R-UKA showed similar radiological results and longer operating time, but reduced complication and revision rates compared to C-UKA. Overall, R-UKA seems to provide relevant benefits over C-UKA in the management of patients undergoing UKA.

Comparison of Time Taken in Conventional versus Active Robotic-Assisted Total Knee Arthroplasty

Background

Computer- and robotic-assisted total knee replacement procedures have been shown to improve the accuracy of the implant size. It also allows dynamic confirmation of the implant and limb alignment during total knee arthroplasty (TKA). The major inhibition of the arthroplasty surgeon in adapting to the robotic-assisted TKA (RA-TKA) is the extra time spent during the registration process and milling of the bone with the robot. The aim of the study was to ascertain the extra time spent during these 2 steps as compared to the conventional TKA (C-TKA).

Methods

It is a prospective study involving 30 patients each in the conventional TKA and RA-TKA operated by the same surgical team. The patients were given a choice between the C-TKA and RA-TKA and consecutive 30 cases in each group were studied by an independent observer. In the C-TKA group, the time for the application of appropriate zigs and execution of the bone cuts and soft-tissue release was recorded whereas in the RA-TKA group, the time taken for fixation of the tibial and femoral arrays and bone registration and bone milling with robot and required soft-tissue release was measured.

Results

The preoperative patient characteristics were the same in both groups. The time taken in the C-TKA and RA-TKA groups was 24.77 ± 1.92 minutes and 25.03 ± 3.27 minutes, respectively, which is statistically insignificant (p = 0.709).

Conclusions

The study findings show that RA-TKA does not take additional time than C-TKA.

Analysis of robot-specific operative time and surgical team anxiety level and its effect on alignment during robot-assisted TKA

Adapting to robotic-assisted (RA) total knee arthroplasty (TKA) is hindered by the surgeon's fear of extra time. The main purpose of this study was to determine the robot's operative time, and the secondary goals were to assess the surgical team's anxiety, implant location and size, and limb alignment. From February to April 2022, 40 participants participated in prospective research. The study included primary Cuvis joint active RA-TKA patients for end-stage arthritis, but conversion of unicompartmental knee arthroplasty to TKA, and patients with prior knee surgery were excluded. The active RA-TKA surgical time included surgeon-dependent and surgeon-independent/active robot time. The surgeon's anxiety was measured using the state-trait anxiety inventory (STAI). The implant size/position and limb alignment were checked by post-operative weight-bearing lateral, anteroposterior, and full-length scanograms. Operative time specifically related to active RA-TKA was higher in the first 10 cases as against 10-20, 20-30 and 30-40 cases which was observed to lower from cohort 2. A similar trend was observed for the surgical team's anxiety levels which seem to lower from cohort 2 (case 10-20). Cumulative experience of active RA-TKA showed no effect on the precision of implant alignment/ size, limb alignment and complications. The study showed progressive improvement in the surgical anxiety scores and reduction in operating time indicating the proficiency gained by the surgical team. Further no learning curve was involved in achieving the implant positioning and sizing, limb alignment with the absence of complications.

Impact of Alignment and Alignment Correction on Outcomes Following Robotic Medial Unicompartmental Knee Arthroplasty

BACKGROUND

The purpose of this study was to retrospectively examine the relationship between preoperative and postoperative alignment in robotic unicompartmental knee arthroplasty (UKA) and postoperative patient-reported outcome measures.

METHODS

A retrospective review of 374 patients who underwent robotic-assisted UKA was conducted. Patient demographics, history, and preoperative and postoperative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) scores were obtained via chart review. Average follow-up period was 2.4 years (range: 0.4 to 4.5 years) to chart review and 9.5 months (range: 6 to 48 months) to latest KOOS-JR. Preoperative and postoperative robotically-measured knee alignment was obtained from operative reports. Incidence of conversion to total knee arthroplasty (TKA) was determined by review of a health information exchange tool.

RESULTS

Multivariate regressions showed no statistically significant relationship between preoperative alignment, postoperative alignment, or degrees of alignment correction and change in KOOS-JR score or achievement of KOOS-JR minimal clinically important difference (MCID) (P > .05). Patients who had >8 degrees of postoperative varus alignment had on average a 20% lower achievement of KOOS-JR MCID compared to patients who had <8 degrees of postoperative varus alignment; however, this difference was not statistically significant (P > .05). There were 3 patients who required conversion to TKA in the follow-up period, with no significant relationship to alignment variables (P > .05).

CONCLUSION

There was no significant difference in KOOS-JR change for those patients who had a larger or smaller degree of deformity correction, and correction did not predict MCID achievement.

Modern Patellofemoral Arthroplasty

INTRODUCTION

The ideal procedure for isolated patellofemoral arthritis is a controversial topic. Patellofemoral arthroplasty (PFA) is an option that aims to restore normal kinematics to the knee while preserving bone. PFA has been shown to have benefits compared with total knee arthroplasty (TKA) in this patient population but has historically had a high failure rate. Revision rates are improving with modern implants and tight indications but still remain higher than TKA. This review summarizes current thinking around PFA using modern implants and techniques in 2023, provides an implant-specific analysis, and assesses how we can improve outcomes after PFA based on the current literature. The aim was to provide an outline of the evidence around PFA on which surgeons can make decisions to optimize patient outcome in this young and active population.

METHODS

Four databases (MEDLINE, Embase, Scopus, and SPORTDiscus) were searched for concepts of patellofemoral joint arthroplasty. After abstract and text review, a screening software was used to assess articles based on inclusion criteria for studies describing indications, outcomes, and techniques for isolated PFA using modern implants, with or without concomitant procedures.

RESULTS

A total of 191 articles were included for further examination, with 62 articles being instructional course lectures, systematic reviews, technique articles, narrative reviews, expert opinions, or meta-analyses. The remaining articles were case reports, trials, or cohort studies. Articles were used to create a thorough outline of multiple recurrent topics in the literature.

CONCLUSIONS

PFA is an appealing option that has the potential to provide a more natural feeling and functioning knee for those with isolated PF arthritis. The high rate of revision is a cause for concern and there are several technical details that should be stressed to optimize results. The uncertain outcome after revision to TKA also requires more investigation. In addition, the importance of strict selection criteria and firm indications cannot be stressed enough to optimize longevity and attempt to predict those who are likely to have progression of tibiofemoral osteoarthritis. The development of new third-generation implants is promising with excellent functional outcomes and a much lower rate of maltracking and implant complications compared with earlier generations. The impact of these implants and improvement in surgical techniques on the revision rate of PFA will be determined from longer-term outcomes.

Global research status and trends in orthopaedic surgical robotics: a bibliometric and visualisation analysis study

This study aimed to investigate and summarise the current state of research and trends in orthopaedic surgical robots. Data on publicly available publications related to orthopaedic surgical robots were extracted by abstract searches of the Web of Science Core Collection database. A bibliometric analysis and detailed reading of the publications were then carried out and the information was visualised using co-authorship analysis, coupling analysis, co-citation analysis and co-occurrence analysis in VOSviewer. With 436 publications included in the study from 1993 to 2022, the overall contribution of publications to the world showed an increasing trend year by year, with a particularly pronounced after 2017, and a geographical trend of predominantly East Asia, North America, and Western Europe. Of these, China was the largest contributor (n = 128). Overall, the UK affiliates and their scholars were leaders in the field, with a high number of publications, total citations, average citations per article and H-index. The most published institutions and authors were Imperial College London (n = 21) and Professor Fares Sahi Haddad of University College London (n = 12), respectively. Journals with a high overall impact on robotic orthopaedic surgery were the Journal of Arthroplasty, Bone Joint Journal, International Journal of Medical Robotics and Computer Assisted Surgery. Keyword co-occurrence network analysis revealed four main clusters: robot-assisted knee, hip arthroplasty, spine surgery, and robotic technology research and development. The top three most common sites for robot-assisted surgery use were the knee, hip and spine. The most used robot types were the knee and spine, with Mako and Arobot being the most used robots for the knee and TiRobot for the spine. This study comprehensively reveals the current status and trends of global research on orthopaedic surgical robots, covering countries, institutions, authors, journals, research hotspots, robot types and surgical sites, providing directional guidance and research ideas for further research on the technological development and clinical evaluation of orthopaedic surgical robots.

Comparative Analysis of Unicompartmental Total Knee Arthroplasty and High Tibial Osteotomy: Time to Total Knee Arthroplasty and Other Outcome Measures

Background

There is no consensus on whether unicompartmental arthroplasty (UKA) or high tibial osteotomy (HTO) is superior for unicompartmental arthritis. While there are studies comparing revision and complication rates, none matched a large number of patients undergoing HTO and UKA in the United States and compared these outcomes. We investigated TKA conversion rate and the complications following HTO or UKA.

Methods

This retrospective study queried the PearlDiver database of all patients undergoing UKA and HTO using CPT codes between January 2011 and January 2020. We compared propensity-matched populations based on age, gender, Charlson comorbidity index, and Elixhauser comorbidity index to compare odds of complications, TKA conversion, and drug use between UKA and HTO groups. Two-independent sample t-test for unequal variances and test of significance were performed.

Results

We found 32,583 UKA patients and 816 HTO patients. Each matched group had 535 patients. One-year complication showed higher risk of pneumonia, hematoma, infection, and mechanical complications among HTO patients. UKA patients used narcotics on average of 10.3 days compared to 9.1 days among HTO patients (P < .01). UKA conversion rates were 4.1%, 5.4%, 7.7%, and 9.2% at 1-, 2-, 5-, and 10-year intervals, respectively. HTO conversion rates were less than 2% at 1- and 2-year intervals, 3.4% at 5-year, and 4.5% at 10-year intervals. This difference was statistically significant at 5- and 10-year intervals (P < .01).

Conclusions

Using large matched cohorts, HTO may be converted to TKA later than UKA in short- to mid-term follow-up, and HTO patients used opioids for shorter duration.

Moving beyond radiographic alignment: applying the Wald Principles in the adoption of robotic total knee arthroplasty

The use of robotics in total knee arthroplasty (TKA) is growing at an exponential rate. Despite the improved accuracy and reproducibility of robotic-assisted TKA, consistent clinical benefits have yet to be determined, with most studies showing comparable functional outcomes and survivorship between robotic and conventional techniques. Given the success and durability of conventional TKA, measurable improvements in these outcomes with robotic assistance may be difficult to prove. Efforts to optimize component alignment within two degrees of neutral may be an attainable but misguided goal. Applying the "Wald Principles" of rationalization, it is possible that robotic technology may still prove beneficial, even when equivalent clinical outcomes as conventional methods, if we look beyond the obvious surrogate measures of success. Robotic systems may help to reduce inventory, streamline surgical trays, enhance workflows and surgical efficiency, optimize soft tissue balancing, improve surgeon ergonomics, and integrate artificial intelligence and machine learning algorithms into a broader digital ecosystem. This article explores these less obvious alternative benefits of robotic surgery in the field of TKA.

Learning curve for active robotic total knee arthroplasty

PURPOSE

Total Knee Arthroplasty (TKA) procedures incorporate technology in an attempt to improve outcomes. The Active Robot (ARo) performs a TKA with automated resections of the tibia and femur in efforts to optimize bone cuts. Evaluating the Learning Curve (LC) is essential with a novel tool. The purpose of this study was to assess the associated LC of ARo for TKA.

METHODS

A multi-center prospective FDA cohort study was conducted from 2017 to 2018 including 115 patients that underwent ARo. Surgical time of the ARo was defined as Operative time (OT), segmented as surgeon-dependent time (patient preparation and registration) and surgeon-independent time (autonomous bone resection by the ARo). An average LC for all surgeons was computed. Complication rates and patient-reported outcome (PRO) scores were recorded and examined to evaluate for any LC trends in these patient related factors.

RESULTS

The OT for the cases 10-12 were significantly quicker than the OT time of cases 1-3 (p < 0.028), at 36.5 ± 7.4 down from 49.1 ± 17 min. CUSUM and confidence interval analysis of the surgeon-dependent time showed different LCs for each surgeon, ranging from 12 to 19 cases. There was no difference in device related complications or PRO scores over the study timeframe.

CONCLUSION

Active Robotic total knee arthroplasty is associated with a short learning curve of 10-20 cases. The learning curve was associated with the surgical time dedicated to the robotic specific portion of the case. There was no learning curve-associated device-related complications, three-dimensional component position, or patient-reported outcome scores.

LEVEL OF EVIDENCE

Level II.

Midterm Survivorship of Robotic-Assisted Lateral Unicompartmental Knee Arthroplasty

BACKGROUND

Lateral unicompartmental knee arthroplasty (UKA) is a popular alternative to total knee arthroplasty (TKA) for patients with isolated lateral compartment osteoarthritis. Few studies have investigated outcomes following robotic-assisted lateral UKA. The purpose of this study is to evaluate mid-term survivorship and patient-reported outcomes of robotic-assisted lateral UKA.

METHODS

A retrospective case series was conducted on all robotic-assisted lateral UKAs performed by a single surgeon between 2013 and 2019. Patient demographics, surgical variables, and Kozinn and Scott criteria were collected. Implant survivorship was estimated using the Kaplan-Meier method with all-cause reoperation and conversion to TKA as endpoints. Participating patients were assessed for patient satisfaction and the Forgotten Joint Score-12. Correlations between patient demographics and patient outcome scores were investigated.

RESULTS

In total, 120 lateral UKAs were identified, 84 of which met inclusion criteria, with a mean follow-up of 4.0 years (range 2.0-7.0). Five-year survivorship was 92.9% (95% confidence interval [CI] 84.5-96.7) with all-cause reoperation as the endpoint, and 100% (95% CI 95.0-100) with conversion to TKA as the endpoint. One patient was converted to TKA after the 5-year mark, resulting in a 6-year survival for conversion to TKA of 88.9% (95% CI 44.9-98.5). Average Forgotten Joint Score-12 score was 82.7/100, and patient satisfaction 4.7/5. Mean coronal plane correction was 2.5° ± 1.9° toward the mechanical axis. Neither final postoperative alignment nor failure to meet classic Kozinn and Scott criteria for UKA resulted in differences in patient-reported outcomes.

CONCLUSION

The current study demonstrates high mid-term survivorship and excellent patient-reported outcomes with robotic-assisted lateral UKA. Robotic-assisted lateral UKA is a viable treatment option for isolated lateral compartment arthritis even in patients who do not meet classic indications.

Versatility and accuracy of a novel image-free robotic-assisted system for total knee arthroplasty

INTRODUCTION

Technological advances alongside increased demand for knee replacement surgery have led to the development of a novel image-free bed rail-mounted robotic-assisted system for total knee arthroplasty (TKA). The device is capable of real-time tracking to accommodate for leg motion during bone resection allowing for precise control and positioning of the bone saw in the planned resection plane. The purpose of this study is to discuss the versatility and accuracy of this novel image-free robotic-assisted technology in TKA.

METHODS AND MATERIALS

The novel robotic-assisted system underwent a stepwise assessment to verify its versatility and accuracy. First, functional accuracy was bench tested to evaluate predetermined surgical plans independent of user variability and anatomic variability compared to conventional instrumentation. This was followed by assessments utilizing cadaveric specimens for resection accuracy, implant positioning, and soft tissue involvement.

RESULTS

Test bench accuracy revealed overall pooled linear positional accuracy of 0.326 ± 0.249 mm and pooled angular positional accuracy of 0.365 ± 0.611°. Resection errors for both robotic and conventional cohorts ranged between 0.6° and 1.9°. Concerning coronal alignment, 33/40 robotic specimen were within ± 1° and 38/40 within ± 3° of the femoral varus-valgus target, compared with 17/40 and 37/40 with conventional instrumentation, respectively. Twenty-four of the 40 robotic specimens were within ± 1° and 40/40 within ± 3° of the tibial varus-valgus target compared with 15/40 and 32/40 with conventional instrumentation, respectively. Soft tissue structures were uncompromised in all robotic-assisted cases. Conventional instruments revealed two cases of partial cleavage of the posterior cruciate ligament and two instances of a compromised posterior medial capsule. There were no significant differences between the two techniques concerning the samples that were uncompromised and fully functional (40/40 vs. 38/40, p = 0.49).

CONCLUSION

The novel image-free robotic-assisted surgical system demonstrates excellent benchtop accuracy to aid bony resection in cadaveric specimens. It offers notable improvement in coronal implant alignment compared to conventional instrumentation.

Preoperative Osteoarthritic Grade Affects Forgotten Joint Status and Patient Acceptable Symptom State After Robotic Arm-Assisted Unicompartmental Knee Arthroplasty

BACKGROUND

This retrospective observational study was designed to investigate the association between radiographic Ahlbäck osteoarthritis (OA) grade and postoperative joint perception in a cohort of patients undergoing medial robotic arm-assisted unicompartmental knee arthroplasty (RA-UKA), using the Forgotten Joint Status and Patient Acceptable Symptom State (PASS) as outcomes.

METHODS

Between January 2014 and May 2019, 660 patients (719 knees) underwent medial RA-UKA at 2 centers. Ahlbäck OA grade was measured on preoperative knee radiographs. Postoperatively, patients were administered the Forgotten Joint Score-12 (FJS-12) and 5-level Likert scale to assess patients' satisfaction. Correlations were described among FJS-12, satisfaction, and Ahlbäck OA grade by means of logistic regression models.

RESULTS

A total of 547 patients (602 knees) were assessed at a mean follow-up of 3.5 years (standard deviation 1.4). A total of 293 cases were graded as Ahlbäck 1 (Group A) and 309 knees were graded as Ahlbäck>1 (Group B). Statistically significant difference was detected in mean FJS-12 (P < .001), but not in the postoperative satisfaction level (P = .06) between the 2 groups. Patients in Group B had a significantly higher probability of attaining a "forgotten knee" after the operation, compared to Group A (P < .05). Cases in Group A had a significantly lower probability of achieving the PASS (P < .01).

CONCLUSION

Patients with higher grades of OA (Ahlbäck>1) were more likely to attain a "forgotten knee," while patients with less severe OA (Ahlbäck 1) were less likely to achieve the PASS after RA-UKA. Although patients with less severe OA reported fairly good outcome, cases in which the results will be poorer are currently difficult to predict.

Robotic-Assisted versus Manual Unicompartmental Knee Arthroplasty: Contemporary Systematic Review and Meta-analysis of Early Functional Outcomes

Robotic-assisted unicompartmental knee arthroplasty (RA-UKA) aims to improve accuracy of component placement. Studies have shown improvement in radiographic positioning/alignment with RA-UKA but have not addressed clinical outcome measures (COMs). The purpose of this study was to determine if RA-UKA is associated with improved early revision rates and functional outcome scores (FOS) compared with manual UKA. A systematic review of all English language articles from 1999 to 2019 on RA-UKA using Medline, EMBASE, Scopus, and Web of Science databases identified 277 studies. Seven (three randomized controlled trials) met inclusion criteria. Revision rates/FOS were aggregated for RA-UKA and manual UKA; a forest plot was constructed utilizing inverse variance/Mantel-Haenszel fixed-effects meta-analysis. The seven articles included a total of 363 RA-UKA patients and 425 manual UKA patients. Mean age was 66 ± 3.5 and 65 ± 4.0 years, and mean body mass index (BMI) was 26.8 ± 2.1 and 27.1 ± 1.5 kg/m², respectively. Mean follow-up was 25.5 months (4.5-48) and 29.1 months (4.5-48) for RA-UKA and manual UKA, respectively. At latest follow-up, RA-UKA patients showed a 26% ± 12 improvement in COMs versus 24% ± 12 improvement for manual UKA patients (p = 0.6). The revision rate was 3% for both groups (p = 0.8); however, a meta-analysis of RCTs showed no difference. Robotic and manual UKAs offer comparable improvements in pain, FOS, and revision rates. The effects of follow-up duration, ceiling effects of COMs, and surgeon experience remain unknown. Future studies comparing robotic versus manual UKAs with longer term follow-up may inform further benefits of each, with respect to component durability, alignment, and functional improvement.

Comparing clinical and radiographic outcomes of robotic-assisted, computer-navigated and conventional unicompartmental knee arthroplasty: A network meta-analysis of randomized controlled trials

Introduction

The purpose was to compare robotic assisted (RA), computer navigated (CN), and conventional UKA techniques.

Methods

Databases were queried for data on study characteristics, UKA systems, complications, and tibiofemoral alignment.

Results

Four RA and six CN RCTs were identified. No significant differences were found in operative time, tibiofemoral alignment, and reoperation rates when comparing RA or CN to conventional UKA. RA UKA resulted in a significantly lower risk of complications compared to conventional UKA.

Conclusions

RA UKA results in fewer complications than conventional UKA with a clinically significant increase in operative time. All groups were similar in remaining evaluated parameters.

[Focal femoral resurfacing and unicompartmental knee replacement : Between osteotomy and total knee replacement]

Unicompartmental knee arthroplasty, especially for both femorotibial compartments of the knee, is an established partly joint-saving treatment option for osteoarthritis of the knee if the disease is limited to one compartment. Even smaller implants or resurfacing of the patellofemoral joint have been shown-in smaller patient collectives-to have the potential to yield good clinical results.

A progressive scholarly acceptance analysis of robot-assisted arthroplasty: a review of the literature and prediction of future research trends

Robot-assisted arthroplasty (RAA) is increasingly practised in orthopaedic surgery. The aim of this study was to perform a bibliometric analysis of all published primary research into RAA and to apply the Progressive Scholarly Acceptance (PSA) model to evaluate its acceptance as an orthopaedic surgical technique. A literature search was performed that included all peer-reviewed, primary, English language publications on RAA from its introduction in 1992 up to 2019. RAA was defined as robot-assisted hip or knee arthroplasty. A bibliometric analysis was performed to categorise articles by type of study and level of evidence. Studies were also categorised as initial investigations (II) or refining studies (RS). A PSA analysis was performed, with the end-point being defined as the point in time when the number of RS exceeded the number of II. Of the 199 studies originating from 19 countries and 101 institutions, only 16 (8.04%) were randomised-controlled trials. Fifty-one percent of studies had been published since 2015. Using PSA analysis, 161 (80.9%) studies were categorised as II and 38 (19.1%) were categorised as RS. This demonstrates that RAA has not yet reached the point of scholarly acceptance. Scholarly acceptance of RAA as an orthopaedic surgical technique has yet to be reached. However, there has been an exponential increase in the number of publications on RAA in the last 5 years, reflecting renewed interest this technique. We predict that, for the next 5 years, RAA will remain in the experimental phase due to the rapid development of new technology in this field.

Low femoral component prominence negatively influences early revision rate in robotic unicompartmental knee arthroplasty

PURPOSE

The revision rate of unicompartmental knee arthroplasty (UKA) is higher than in total knee arthroplasty (TKA), and implant positioning may play a role. In combination with a pre-operative CT, robotic UKA may provide the ability to position the implants more precisely. The aim of this study was to investigate the influence of component prominence relative to the native joint surface on early outcomes and revisions. The hypothesis was that aiming for restoration of joint space to 0.5-1.5 mm will improve outcomes.

METHODS

Retrospective analysis of prospectively collected data of 94 patients undergoing robotic-assisted UKA (Mako, Stryker) was performed. The 'prominence' of the implant surface relative to the native bony surface in sagittal plane, hip-knee-ankle (HKA) correction in coronal plane was documented intraoperatively. The mean achieved gap between two components under valgus stress captured in at least 5 different flexion angles was calculated. These were then analysed for impact on early revision rate and outcomes, stratified by gender.

RESULTS

Median HKA correction was 3.5° (range 0°-9.5°). Median femoral prominence was 1.5 mm (range - 0.6 to 4 mm) and median tibial prominence was 4.3 mm (2-7 mm). The median achieved gap was 1.0 mm (- 1.2 to 2.8 mm). There was no difference in achieved correction between men and women (p = n.s.) but men had a higher achieved combined prominence than women (p < 0.001). PROMs did not correlate with the average gap (p = n.s.) nor with combined prominence (p = n.s.). Two patients underwent an early revision. Lower femoral prominence was a significant predictor of revision (p = 0.045; OR = 0.21; 95% CI 0.000-0.918).

CONCLUSION

Female patients need less component prominence to achieve the same average gap balance through a range of motion, without correlation with patient's height. Intraoperatively low femoral prominence could be a reason for early revision.

LEVEL OF EVIDENCE

IV.

Robotic-assisted surgery in medial unicompartmental knee arthroplasty: does it improve the precision of the surgery and its clinical outcomes? Systematic review

There is a high prevalence of knee osteoarthritis that affects only the medial tibiofemoral compartment. In this group of patients with severe disease, the medial unicompartmental knee arthroplasty (UKA) is an excellent choice. However, this technique has a great learning curve due to the lower tolerance of improper positioning and alignment. In this context, the robotic-assisted surgery (RAS) arises as an option to improve the accuracy and secondarily enhance the clinical outcomes related to the UKA. The objective in this study is to determine if there are significant advantages with the use of RAS over conventional surgery (CS). In the systematic review of the literature, classification of the results in three main subjects: (A) precision and alignment; (B) functional results and clinical parameters; (C) survivorship. We found 272 studies, of which 15 meet the inclusion and exclusion criteria. There is mostly described that RAS significantly improves the accuracy in position (80-100% of planned versus performed P < 0.05), alignment (2-3 times less error variance P < 0.05) and selection of the proper size of the implants (69.23% of correct size femoral implants versus 16.67% using CS P < 0.0154). Recently, there is mild evidence about benefits in the early rehabilitation and post-operative pain, but in all studies reviewed, there is no advantages of RAS in the long-term functional evaluation. There is no strong literature that supports a longer survival of the prothesis with RAS, being the longest mean follow-up reported of 29.6 months. RAS is a useful tool in increasing the precision of the medial UKA implant placement. However, there is still a lack of evidence that properly correlates this improvement in accuracy with better clinical, functional and survival results.

The most influential papers in unicompartmental knee arthroplasty

Purpose

Unicompartmental knee arthroplasty (UKA) is a treatment option for anteromedial osteoarthritis of the knee. The number of UKA has been increasing constantly worldwide in recent decades. The aim of this study was to determine the most frequently cited scientific articles addressing this subject and to establish a ranking of the 50 most influential papers.

Methods

The 50 most cited articles related to UKA were searched in Web of Science® (Clarivate Analytics, Penn., USA) by the use of defined search terms. All types of scientific papers with reference to this topic were ranked according to the absolute number of citations and analyzed for the following characteristics: journal title, year of publication, number of citations, citation density, geographic origin, article type, and level of evidence.

Results

The 50 most cited articles had up to 453 citations. Most papers were published in the Journal of Bone and Joint Surgery (British volume). More than half of the articles were published in the 2000s and 2010s (n = 30). Ten countries contributed to the top 50 list, with most contributions from the UK (n = 17). Most articles could be attributed to the category of Clinical Science (n = 33), and most reported level IV studies.

Conclusion

Most of the frequently cited articles in UKA are clinical studies that have a low level of evidence. Few basic scientific studies could be identified, which suggests that most product development is done by commercial companies.

Robots in the Operating Room During Hip and Knee Arthroplasty

PURPOSE OF THE REVIEW

The utilization of technology has increased over the last decade across all surgical specialties. Robotic-assisted surgery, among the most advanced surgical technology, applied to hip and knee arthroplasty has experienced rapid growth in utilization, surgical applications, and robotic platforms. The goal of this study is to provide a comprehensive review of the most commonly utilized robotic platforms for hip and knee arthroplasty and the most up to date literature on the benefits and limitations of robotic arthroplasty.

RECENT FINDINGS

Studies consistently demonstrate that that robotic-assisted surgery during total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA) improves component position and alignment. There is also growing evidence that robotic-assisted UKA improves clinical outcomes and implant survivorship and, therefore, may be cost-effective. However, there remains to be convincing evidence that robotic-assisted arthroplasty improves clinical outcome measures or reduces revision rates for THA and TKA. Potential disadvantages of robotic arthroplasty remain, including a learning curve, potential for additional radiation exposure preoperatively, and the financial costs. Robotic hip and knee arthroplasty remains attactive as studies show that it consistently improves implant position and alignment over conventional techniques. There is growing evidence that robotic UKA may improve patient outcomes and reduce revision rates, but further study is needed. In addition, further and longer-term studies are needed to determine if improved component position and alignment in TKA and THA leads to improved clinical outcomes and reduced revision rates.

Clinical results and short-term survivorship of robotic-arm-assisted medial and lateral unicompartmental knee arthroplasty

PURPOSE

The aim of this multicentre, retrospective, observational study was to determine the incidence of revision and clinical results of a large cohort of robotic-arm-assisted medial and lateral UKAs at short-term follow-up. It was hypothesized that patients who receive robotic-arm-assisted UKA will have high survivorship rates and satisfactory clinical results.

METHODS

Between 2013 and 2016, 437 patients (470 knees) underwent robotic-arm-assisted medial and lateral UKAs at two centres. Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score 12 (FJS-12) and Short-Form Physical and Mental Health Summary Scales (SF-12) were administered to estimate patients' overall health status pre- and post-operatively. Results were dichotomized as 'excellent' and 'poor' if KOOS/FJS-12 were more than or equal to 90 and SF-12 was more or equal to 45. Associations between patients' demographic characteristics and clinical outcomes were investigated. Post-operative complications and pain persistence were recorded.

RESULTS

Following exclusions and losses to follow-up, 338 medial and 67 lateral robotic-arm-assisted UKAs were assessed at a mean follow-up of 33.5 and 36.3 months, respectively. Three medial UKAs were revised, resulting in a survivorship of 99.0%. No lateral implants underwent revision (survivorship 100%). On average, significant improvement in all clinical scores was reported in both medial and lateral UKA patients. In medial UKA patients, male gender was associated with higher probability of better scores in overall KOOS, FJS-12 and in specific KOOS subscales. No other associations were reported between biometric parameters and outcome for either medial or lateral UKA.

CONCLUSIONS

Robotic-assisted medial and lateral UKAs demonstrated satisfactory clinical outcomes and excellent survivorship at 3-year follow-up. Continued patient follow-up is needed to determine the long-term device performance and clinical satisfaction.

LEVEL OF EVIDENCE

Retrospective cohort study, Level IV.

The three-year survivorship of robotically assisted versus non-robotically assisted unicompartmental knee arthroplasty

AIM

There has been a significant reduction in unicompartmental knee arthroplasty (UKA) procedures recorded in Australia. This follows several national joint registry studies documenting high UKA revision rates when compared to total knee arthroplasty (TKA). With the recent introduction of robotically assisted UKA procedures, it is hoped that outcomes improve. This study examines the cumulative revision rate of UKA procedures implanted with a newly introduced robotic system and compares the results to one of the best performing non-robotically assisted UKA prostheses, as well as all other non-robotically assisted UKA procedures.

METHODS

Data from the Australian Orthopaedic Association National Joint Arthroplasty Registry (AOANJRR) for all UKA procedures performed for osteoarthritis (OA) between 2015 and 2018 were analyzed. Procedures using the Restoris MCK UKA prosthesis implanted using the Mako Robotic-Arm Assisted System were compared to non-robotically assisted Zimmer Unicompartmental High Flex Knee System (ZUK) UKA, a commonly used UKA with previously reported good outcomes and to all other non-robotically assisted UKA procedures using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship.

RESULTS

There was no difference in the rate of revision when the Mako-assisted Restoris UKA was compared to the ZUK UKA (zero to nine months: HR 1.14 (95% CI 0.71 to 1.83; p = 0.596) vs nine months and over: HR 0.66 (95% CI 0.42 to 1.02; p = 0.058)). The Mako-assisted Restoris had a significantly lower overall revision rate compared to the other types of non-robotically assisted procedures (HR 0.58 (95% confidence interval (CI) 0.42 to 0.79); p < 0.001) at three years. Revision for aseptic loosening was lower for the Mako-assisted Restoris compared to all other non-robotically assisted UKA (entire period: HR 0.34 (95% CI 0.17 to 0.65); p = 0.001), but not the ZUK prosthesis. However, revision for infection was significantly higher for the Mako-assisted Restoris compared to the two comparator groups (ZUK: entire period: HR 2.91 (95% CI 1.22 to 6.98; p = 0.016); other non-robotically assisted UKA: zero to three months: HR 5.57 (95% CI 2.17 to 14.31; p < 0.001)).

CONCLUSION

This study reports comparable short-term survivorship for the Mako robotically assisted UKA compared to the ZUK UKA and improved survivorship compared to all other non-robotic UKA. These results justify the continued use and investigation of this procedure. However, the higher rate of early revision for infection for robotically assisted UKA requires further investigation. Cite this article: Bone Joint J 2020;102-B(3):319-328.

Total Joint Arthroplasty in Patients with Inflammatory Rheumatic Diseases

Since its introduction, total joint arthroplasty (TJA) has improved the quality of life of patients with degenerative joint disorders. In the last decades, a number of conventional and biological disease-modifying antirheumatic drugs have become available for the treatment of patients with inflammatory rheumatic diseases (IRD), leading to a reduction in the need to undergo TJA. However, TJA is still frequently performed in IRD patients. Both rheumatologists and orthopedics should be aware that patients with IRD have a peculiar perioperative risk profile due to disease-related, patient-related, and surgery-related risk factors. On the basis of current evidence, TJA is a safe procedure for IRD patients as long as an accurate risk stratification and a multidisciplinary approach are applied. We here describe the current strategies for an appropriate surgical management of osteoarthritis in IRD patients and the fascinating opening perspectives that surgeons and clinicians may expect in the future.