Current state of computer navigation and robotics in unicompartmental and total knee arthroplasty: a systematic review with meta-analysis

MAKO CT-based robotic arm-assisted system is a reliable procedure for total knee arthroplasty: a systematic review

PURPOSE

The aim of this study was to investigate the clinical and radiological results of the MAKO CT-based robotic-assisted system for total knee arthroplasty (TKA).

METHODS

A PRISMA systematic review was conducted using four databases (MEDLINE, EMBASE, Pubmed, GOOGLE SCHOLAR) to identify all clinical and radiological studies reporting information regarding the use and results of the CT-based robotic-assisted system to perform TKA between 2016 and 2020. The main investigated outcome criteria were postoperative pain, analgesia requirements, clinical scores, knee range of motion, implant positioning and the revision rate. The ROBINS-I tool (Risk Of Bias In Non-randomized Studies of Interventions) was used to evaluate the quality of included studies and the risk of bias.

RESULTS

A total of 36 studies were identified, of which 26 met inclusion criteria. Of these 26 studies, 14 were comparative. The follow-up varied from 30 days to 17 months. This CT-based, saw cutting Robotic TKA is associated with a significantly lower postoperative pain score (2.6 versus 4.5) and with significantly reduced time to hospital discharge (77 h versus 105), compared with conventional TKA. The two comparative studies assessing functional outcomes at 1 year reported significantly better functional scores with CT-based robotic TKA compared with conventional TKA (WOMAC score: 6 ± 6 versus 9 ± 8 (p < 0.05); KSS function score: 80 versus 73 (p = 0.005)). Only three comparative studies assessed implant positioning, and these reported better implant positioning with CT-based robotic-assisted TKA.

CONCLUSION

The CT-based robotic-assisted system for TKA reduced postoperative pain and improved implant positioning with equal or slightly superior improvement of the functional outcomes at one year, compared to conventional TKA.

LEVEL OF EVIDENCE

Systematic review level IV.

Electromagnetic Navigated Versus Conventional Total Knee Arthroplasty-A Five-Year Follow-Up of a Single-Blind Randomized Control Trial

BACKGROUND

The objective of this study is to provide the 5-year follow-up results of a randomized study comparing conventional versus electromagnetic computer navigated total knee arthroplasty.

METHODS

Analysis of 127 patients (66 navigated and 61 conventional surgeries) was performed from a prospective, single-blinded, randomized controlled trial. Patient-reported outcome measures were collected at 5 years after surgery and compared with previously published 1-year clinical outcomes. Five-year surgical revision rates were collated and compared between intervention groups.

RESULTS

Overall, there have been continued improvements in the clinical scores of patients in both groups when compared with clinical data at 1 year; however, at 5 years, there is no statistical difference in any of the patient-reported outcome measures between conventional and navigated surgery. Interestingly, improved implant survivorship was observed in the navigated (0% revision rate) compared with the conventional group (4.9% all-cause revision rate).

CONCLUSION

Electromagnetic computer navigated technology produces similar clinical outcomes compared with traditional surgery. Further work is required to monitor implant survivorship, and clinical outcomes with long-term follow-up, to determine the cost effectiveness of this technology.

Robotic-assisted total hip arthroplasty: an economic analysis

Aim: To evaluate 90-day episode-of-care (EOC) resource consumption in robotic-assisted total hip arthroplasty (RATHA) versus manual total hip arthroplasty (mTHA). Methods: THA procedures were identified in Medicare 100% data. After propensity score matching 1:5, 938 RATHA and 4,670 mTHA cases were included. 90-day EOC cost, index costs, length of stay and post-index rehabilitation utilization were assessed. Results: RATHA patients were significantly less likely to have post-index inpatient rehabilitation or skilled nursing facility admissions and used fewer home health agency visits, compared with mTHA patients. Total 90-day EOC costs for RATHA patients were found to be US$785 less than those of mTHA patients (p = 0.0095). Conclusion: RATHA was associated with an overall lower 90-day EOC cost when compared with mTHA. The savings associated with RATHA were driven by reduced utilization and cost of post-index rehabilitation services.

The Impact of Machine Learning on 2D/3D Registration for Image-Guided Interventions: A Systematic Review and Perspective

Image-based navigation is widely considered the next frontier of minimally invasive surgery. It is believed that image-based navigation will increase the access to reproducible, safe, and high-precision surgery as it may then be performed at acceptable costs and effort. This is because image-based techniques avoid the need of specialized equipment and seamlessly integrate with contemporary workflows. Furthermore, it is expected that image-based navigation techniques will play a major role in enabling mixed reality environments, as well as autonomous and robot-assisted workflows. A critical component of image guidance is 2D/3D registration, a technique to estimate the spatial relationships between 3D structures, e.g., preoperative volumetric imagery or models of surgical instruments, and 2D images thereof, such as intraoperative X-ray fluoroscopy or endoscopy. While image-based 2D/3D registration is a mature technique, its transition from the bench to the bedside has been restrained by well-known challenges, including brittleness with respect to optimization objective, hyperparameter selection, and initialization, difficulties in dealing with inconsistencies or multiple objects, and limited single-view performance. One reason these challenges persist today is that analytical solutions are likely inadequate considering the complexity, variability, and high-dimensionality of generic 2D/3D registration problems. The recent advent of machine learning-based approaches to imaging problems that, rather than specifying the desired functional mapping, approximate it using highly expressive parametric models holds promise for solving some of the notorious challenges in 2D/3D registration. In this manuscript, we review the impact of machine learning on 2D/3D registration to systematically summarize the recent advances made by introduction of this novel technology. Grounded in these insights, we then offer our perspective on the most pressing needs, significant open problems, and possible next steps.

Robot-Assisted versus Conventional Total and Unicompartmental Knee Arthroplasty: A Meta-analysis of Radiological and Functional Outcomes

The study aims to provide an up-to-date systematic review and meta-analysis comparing radiological and functional outcomes of total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) using either robotic assistance or conventional methods from the latest assemblage of evidence. This study was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. All studies in PubMed, EMBASE, Medline, and Cochrane that reported radiological and functional outcomes after TKA or UKA with either robotic or conventional methods were included in the review. Selected endpoints for random effects, pairwise meta-analysis included operative details, radiological outcomes (mechanical axis, component angle deviation, and outliers), and functional outcomes (American Knee Society Score, Knee Society Function Score, revision and complication rate, range of motion (ROM), Hospital for Special Surgery score, and Western Ontario and McMaster Universities Osteoarthritis Index). A total of 23 studies comprising 2,765 knees were included from the initial search. Robot-assisted TKA and UKA were associated with significantly better component angle alignment accuracy (low-to-high quality evidence) at the cost of significantly greater operation time. Robot-assisted UKA was found to have significantly better short-term functional outcomes compared with conventional UKA (moderate-to-high quality evidence). Robot-assisted TKA, however, did not exhibit significantly better short- and midterm subjective knee outcome scores compared with its conventional counterpart (high-quality evidence). Robot-assisted TKA and UKA were associated with nonstatistically significant improved ROM and lesser rates of revision. Robot-assisted total and unicompartmental knee arthroplasty leads to better radiological outcomes, with no significant differences in mid- and long-term functional outcomes compared with conventional methods for the former. Larger prospective studies with mid- and long-term outcomes are required to further substantiate findings from the present study.

Outcomes of Computer-Assisted Total Knee Arthroplasty Compared to Conventional TKA: A Bicentric Controlled Retrospective Clinical Study

Despite the globally ascertained success of Total Knee Arthroplasty (TKA) procedure, 20% of patients are still unsatisfied with the surgery results. The purpose of the study is to identify the functional and radiological outcomes of the computer-assisted (CAS) TKA compared to the conventional technique. The clinical databases and medical records of both clinical sites were retrospectively analyzed, and then according to study time-lapse, inclusion, and exclusion criteria, eligible patients were retrieved and included. A total of 42 patients that underwent to CAS TKA (NAVI) and 61 patients that underwent to Conventional TKA (CONV) were included. The NAVI group reported a statistically significant higher surgical time. A lower intraoperative blood loss was found in the computer-assisted group, though this difference was not statistically significant. Implant survival analysis at two years did not show differences between groups during the follow-up period. At two years, follow-up postoperative intergroup analysis showed no statistically significant difference between groups. According to the radiologic analysis, the NAVI group showed comparable outcomes to the conventional group. The present study showed that there was no clinical and radiological difference between CAS arthroplasty and conventional technique.

[Application and research progress of robotic-arm in total knee arthroplasty]

OBJECTIVE

To summarize the application and research progress of robotic-arm in total knee arthroplasty (TKA).

METHODS

Relevant literature at home and abroad was extensively reviewed to analyze the advantages and disadvantages of robotic-arm assisted TKA (RATKA).

RESULTS

Accurate reconstruction of lower extremity alignment and rotation alignment, accurate osteotomy and implant prosthesis in TKA are very important to improve the effectiveness and prolong the life of the prosthesis. Traditional TKA deviations occur in key links such as osteotomy due to operator's operation. RATKA solves the above problems to a certain extent and can assist accurate osteotomy and implant prosthesis, and protect the soft tissues around the knee joint. Patients' satisfaction after RATKA is high, and the operator's learning curve is shorter, which improves the efficiency of the operation. But it also has disadvantages such as prolonged operation time, increased complications and medical costs.

CONCLUSION

Preliminary clinical application studies have shown that RATKA has satisfactory effectiveness, but its definite advantages compared with traditional TKA need to be confirmed by a large number of randomized controlled trials and long-term follow-up.

CT-Based 3D Reconstruction of Lower Limb Versus X-Ray-Based 3D Reconstruction: A Comparative Analysis and Application for a Safe and Cost-Effective Modality in TKA

AIM

Patient Specific Instrumentation (PSI) with 3D bone models have been used to improve the outcomes of Total Knee Arthroplasty (TKA). The PSI, however, needs a CT (Computed tomography)/MRI scan to reproduce a bone-based model. However, CT is not a routine imaging method in the TKA and has challenges such as high radiation exposure and increased investigation cost. Any technology or software which could accurately recreate 3D bone models using X-ray would be a cheaper and safer tool. This study is based on one such technology (XrayTo3D^®) using X-ray to 3D as an alternative to other image-based 3D bone models and PSI available in the market. This study compares the accuracy of XrayTo3D^® versus a Conventional CT to 3D, in the reconstruction of lower limb bones (femur and tibia).

METHOD

In an analysis of 45 lower limbs, 11 anatomical parameters were measured [Medial Proximal Tibial Angle-MPTA, Tibial(T)-torsion, T-slope, T-length, Mechanical Lateral Distal Femoral Angle (mLDFA), F-version, F-length, Distal femoral Medio lateral width (F-ML), Distal Femoral Antero Posterior (F-AP), Proximal Tibia Antero Posterior (T-AP), Proximal Tibia Medio Lateral (T-ML) based on landmarks selected by three orthopaedic surgeons(numbers of the authors superscript), on two groups of 3D models, one reconstructed using XrayTo3D^® and the other using CT. Mean and standard-deviation values were measured for all the parameters in both the groups. Statistical association between both the groups was measured by Pearson's correlation coefficient. Two-sided t tests of the mean values were calculated to compare the two measurement methods. The interobserver reproducibility within each group was measured by the intraclass correlation coefficient (ICC). Point-to-surface (P2S) error, in the distal femur and proximal tibia regions of the models reconstructed using XrayTo3D^®, were also measured.

RESULTS

For all the 11 parameters, no statistically significant difference was found between the 2 groups (p > 0.05). Pearson's correlation coefficients for all the parameters were not significant. The interobserver reproducibility was ranging from 0.90 to 1.00 and 0.90 to 1.00 for the XrayTo3D^® and CT groups, respectively. The mean P2S distance was 1.0 mm in distal femur and 1.1 mm in proximal tibia which was within the acceptable limits.

CONCLUSION

The reconstruction accuracy of the XrayTo3D^® is an accurate, safe and cost effective as compared to a CT-based method.

Clinical impact of intraoperative cone beam tomography and navigation for displaced acetabular fractures: a comparative study at medium-term follow-up

INTRODUCTION

The use of per-operative cone beam tomography imaging for displaced acetabular fractures yields increased post-operative articular reduction accuracy. This study evaluates the need for total hip replacement (THR) and hip-related functional outcomes in patients with displaced acetabular fractures treated with O-ARM guidance compared to those treated under C-ARM guidance.

MATERIALS AND METHODS

This is a prospective matched cohort study. Adult patients (35) with acetabular fractures operated under O-ARM guidance were included. These were matched (age, fracture type) to classically treated patients (35) from our data base. The primary outcome was the need for THR during three year follow-up period. Secondary outcomes were functional scores [Harris Hip score (HHS), Postel-Merle d'Aubigné (PMA)] and hip osteoarthritis grade at three year follow-up. Correlation between reduction gap and THR was evaluated.

RESULTS

At three years, five patients were lost to follow-up in O-ARM group and four in control group. Two patients (6.66%) in the O-ARM group needed THR compared to eight patients in controls (25.80%) (p = 0.046). Hip X-ray osteoarthritis grade averaged 0.00 in patients without THR in O-ARM group compared to 0.22 in patients without THR in controls (p = 0.008). HHS averaged 95.79 in patients without THR in O-ARM group, compared to 93.82 in patients without THR in the control group (p = 0.41%). PMA averaged 17.25 in patients without THR in the O-ARM group compared to 17.04 in patients without THR in group 2 (p = 0.37). Evaluation of correlation between reduction gap and THR rate yielded OR = 1.22 (1.06-1.45).

DISCUSSION

Increased accuracy in articular reduction, with per-operative three-dimensional control of impaction, in acetabular fractures led to significantly less need for THR in patients treated under O-ARM. Patients in both groups are comparable for functional outcomes because those with the lowest scores were offered THR. Per-operative cone beam guidance and navigation use are recommended in tertiary referral centres for acetabular trauma.

Robotic-assisted unicompartmental knee arthroplasty: a review

Purpose

Presented here is an up-to-date review concerning robotic-assisted unicompartmental knee arthroplasty (rUKA), including its rationale, operative system, pros and cons.

Methods

We did a systematic research in electronic databases, including PubMed, Cochrane Library, Web of Science, and Embase up to March 30, 2020 to retrieve literature pertaining to rUKA. The search strategies “(robotic* AND knee arthroplasty OR knee replacement)” and “(knee arthroplasty OR knee replacement NOT total)” were used. Studies describing rUKA and clinical trials, dry bone or cadaveric researches regarding technologies, positioning, alignment, function, or survivorship of implants were included in this review. All retrieved studies were first browsed for eligibility on the basis of title and abstract, and the selected studies were further evaluated by reading full text for final inclusion.

Results

Robotic-assisted technology has been found to increase the accuracy of bone preparation and implant placement, reduce technical variability and outliers, and enhance reproduction of limb alignment. Additionally, early clinical outcomes were excellent, but mid-term follow-up showed no superiority in component survivorship. The potential drawbacks of the robotic-assisted technology include relatively-low time- and cost-effectiveness, development of some rUKA-related complications, and lack of support by high-quality literature.

Conclusion

This review shows that rUKA can decrease the number of outliers concerning the optimal implant positioning and limb alignment. However, due to absence of extensive studies on clinical outcomes and long-term results, it remains unclear whether the improved component positioning translates to better clinical outcomes or long-term survivorship of the implant. Nevertheless, since an accurate implant position is presumably beneficial, robotic-assisted technology is worth recommendation in UKA.

Computer-Navigated versus Conventional Total Knee Arthroplasty: A Meta-Analysis of Functional Outcomes from Level I and II Randomized Controlled Trials

The main purpose of this article is to provide an up-to-date systematic review and meta-analysis comparing functional outcomes of total knee arthroplasty using either computer navigation (NAV-TKA) or conventional methods (CON-TKA) from the latest assemblage of evidence. This study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology guidelines. All Level I and II randomized controlled trials (RCTs) in PubMed, EMBASE, and Cochrane that compared functional outcomes after NAV- and CON-TKA were included in the review. Selected end points for random effects, pairwise meta-analysis included Knee Society Knee Score (KSKS), KS Function Score (KSFS), KS Total Score (KSTS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and range of motion at three arbitrary follow-up times. A total of 24 prospective RCTs comprising 3,778 knees were included from the initial search. At long-term follow-up (>5 years), NAV-TKA exhibited significantly better raw KSKS (p = 0.001) (low-quality evidence), contrary to CON-TKA, which reflected significantly better raw KSTS (p = 0.004) (high-quality evidence). While change scores (KSKS, WOMAC) from preoperative values favor CON-TKA at short-term (<6 months) and medium-term follow-up (6-60 months), long-term follow-up change scores in KSKS suggest the superiority of NAV-TKA over CON-TKA (p = 0.02) (very low-quality evidence). Overall, sizeable dispersion of nonstatistically significant functional outcomes in the medium term was observed to eventually converge in the long term, with less differences in functional outcome scores between the two treatment methods in short- and long-term follow-up. While raw functional outcome scores reflect no differences between NAV and CON-TKA, long-term follow-up change scores in KSKS suggest superiority of NAV-TKA over its conventional counterpart. Prospective studies with larger power are required to support the pattern of diminishing differences in functional outcome scores from medium- to long-term follow-up between the two modalities.

Improved sizing with image-based robotic-assisted system compared to image-free and conventional techniques in medial unicompartmental knee arthroplasty

AIMS

Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique.

METHODS

Three groups of 93 medial UKAs were assessed. The first group was performed by a conventional technique, the second group with an image-free robotic-assisted system (Image-Free group), and the last group with an image-based robotic arm-assisted system, using a preoperative CT scan (Image-Based group). There were no demographic differences between groups. We compared six parameters on postoperative radiographs to assess UKA sizing. Incorrect sizing was defined by an over- or under-sizing greater than 3 mm.

RESULTS

There was a higher rate of tibial under-sizing posteriorly in the conventional group compared to robotic-assisted groups (47.3% (n = 44) in conventional group, 29% (n = 27) in Image-Free group, 6.5% (n = 6) in Image-Based group; p < 0.001), as well as a higher rate of femoral under-sizing posteriorly (30.1% (n = 28) in conventional group, 7.5% (n = 7) in Image-Free group, 12.9% (n = 12) in Image-Based group; p < 0.001). The posterior femoral offset was more often increased in the conventional group, especially in comparison to the Image-Based group (43% (n = 40) in conventional group, 30.1% (n = 28) in Image-Free group, 8.6% (n = 8) in Image-Based group; p < 0.001). There was no significant overhang of the femoral or tibial implant in any groups.

CONCLUSION

Robotic-assisted surgical techniques for medial UKA decrease the risk of tibial and femoral under-sizing, particularly with an image-based system using a preoperative CT scan. Cite this article: Bone Joint J 2021;103-B(4):610-618.

Navigation assisted total knee arthroplasty in 54,114 patients: No increased risk in acute complications and hospital utilisation

BACKGROUND

The advent of navigation in total knee arthroplasty (TKA) has generated interest in attempt to improve component positioning as desired and clinical outcomes. The aim of this study was to evaluate 90-day complication and cost of navigation-assisted TKAs (NTKA) compared to conventional TKAs (CTKA) using a national database.

METHODS

A retrospective review of national database was conducted on all patients who underwent TKA from 2010 and 2017. The cohort was stratified into NTKA and CTKA subcohorts, excluding cases utilizing robotics.

RESULTS

NTKA was associated with a significant decrease in 90-day postoperative major and minor complications. NTKA was also associated with a decrease in 90-day hospital utilization with lower rates of emergency department visits and readmissions. The cost of hospitalization and total 90-day costs were lower in NTKA, with an average savings of $800.

CONCLUSION

The adoption of navigation in TKA is safe and efficaceous compared to CTKA.

LEVEL OF EVIDENCE

III. Retrospective cohort study.

Is robotic-assisted unicompartmental knee arthroplasty a safe procedure? A case control study

PURPOSE

The hypotheses were that firstly there is few early specific complications due to the use of a robotic-assisted system for unicompartimental knee arthroplasty (UKA), and secondly there are less revisions and complications after robotic-assisted UKA than after conventional UKA.

METHODS

200 robotic-assisted UKA (175 patients) and 191 conventional UKA (179 patients) were performed between 2013 and 2018 from the same center. Revisions, intraoperative and postoperative complications, functional and radiological results were collected at the most recent follow-up.

RESULTS

At the most recent follow-up (≥ 1 year), revision rates were 4% (n = 8/200) for robotic-assisted UKA and 11% (n = 21/191) for conventional UKA (p = 0.014). Reoperation rates without implant removal were comparable in the robotic and conventional group (7.3% vs 8.6%). Complication rates for stiffness (4.7% vs 4.2%) and infection (1% vs 1.6%) were comparable in both groups. There was no specific complication related to the robotic-assisted system (no soft tissue or bone lesion caused by the use of the robotic-assistance and no complication related to the use of navigation pins). The KSS function scores were higher following robotic-assisted UKA (p = 0.01). Satisfaction rates and contralateral OA were comparable in the two groups.

CONCLUSION

No complications due to the robotic-assisted system were found in this study. There was no difference in the general complications rate between both groups. Robotic-assisted UKA has a lower revision rate compared to conventional technique UKA at the short-term follow-up.

LEVEL OF EVIDENCE

III.

CLINICAL RELEVANCE

This is the first paper comparing revision rate and clinical outcome between UKA performed using the NAVIO robotic system and a conventional technique and searching for specific complication related to the use of the NAVIO robotic system.

Linked kinematic knee balancing in unicompartmental knee arthroplasty

The traditional approach of restoring a neutral mechanical axis to the lower extremity during total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) has long been favored due its consistency and reproducibility. The kinematic alignment approach, which accounts for the patient's natural knee alignment and is commonly a few degrees varus to the mechanical axis, has gained popularity in recent years as a technique which reestablishes a more anatomic alignment. Linked Anatomic Kinematic Arthroplasty (LAKA), an extension of the kinematic approach that employs computer-assisted surgical (CAS) navigation, can improve the accuracy and precision of kinematic measurements in unicompartmental knee arthroplasties. This article will describe the LAKA technique in UKA and review early clinical outcomes associated with this technique.

Robotic-assisted vs conventional surgery in medial unicompartmental knee arthroplasty: a clinical and radiological study

BACKGROUND

The use of unicompartmental knee arthroplasty (UKA) has increased and new technologies have been developed to improve patient survival and satisfaction, soft tissue balance, alignment, and component size. Robot-assisted systems offer an increase in surgical precision and accuracy. The purpose of this study is to evaluate the precision of component position using five radiological parameters in conventional and robotic-assisted medial UKA using the NAVIO system.

METHODS

A cohort study was designed for patients who underwent medial UKA between April 2017 and March 2019 in a single center. Patients were allocated in the conventional (UKA-C) or robotic-assisted (UKA-R) group. The variables analyzed were age, gender, affected knee side, length of hospital stay, surgical time, and radiological measurements such as anatomical medial distal femoral angle (aMDFA), anatomical medial proximal tibial angle (aMPTA), tibial slope, the sagittal femoral angle, and the component size. A target was defined for each measurement, and a successful UKA was defined if at least four radiological measures were on target after surgery. Also, patients' reported outcomes were evaluated using the Oxford Knee Score (OKS) and a numeric rating scale (NRS) for pain.

RESULTS

Thirty-four patients were included, 18 of them underwent UKA-R. The success rate for UKA in the UKA-R group was 87%; meanwhile, in the UKA-C group this was 28%, this difference was significant and powered (Fisher's exact test, p = 0.001; 1 - β = 0.95). Also, a 5-point difference in favor of the UKA-R group in the median OKS (p = 0.01), and a significantly lower median NRS for pain (p < 0.000) were found after surgery.

CONCLUSIONS

UKA-R achieved more precision in the radiological parameters' measure in this study. Also, UKA-R has a trend towards a better OKS and a lower NRS for pain at short-term follow-up.

Total knee arthroplasty: Latest robotics implantation techniques

The recent introduction of new robotic systems for total knee arthroplasty (TKA) has created somewhat of a craze. Nevertheless, we can ask ourselves whether it is justified to use these new but very costly technologies. The results and limitations of these robotic tools must be analyzed systematically before confirming their benefits. Most of the newest robotic systems are interactive ones. These systems can accurately restore the mechanical axis and can improve the ligament balance and implant positioning. Theoretically, this can lead to better survival, function and outcomes. Recent studies have shown that use of robotics for TKA implantation does not increase the surgery time and does not cause more complications. Nevertheless, the long-term advantages of robotics use in this context remains to be proven. This task will be more difficult since there is currently no consensus as to the ideal positioning of TKA implants for a given patient. The aim of this study is to summarize this topic by answering the following questions: What are the different types of robots that can be used for TKA implantation? Which steps of the TKA surgical procedure are done with robotic arm assistance? What are the outcomes of these new implantation techniques? What are the limitations of these new implantation techniques? LEVEL OF EVIDENCE: V; expert opinion.

No influence of obesity on mid-term clinical, functional, and radiological results after computer-navigated total knee arthroplasty using a gap balancing technique

OBJECTIVE

In obese patients, thick subcutaneous tissue can introduce errors during registration and leg weight can influence gap balancing in navigated TKA. Present study is done to determine if computer navigated TKA using a gap balancing technique can achieve consistent accuracy for limb and component alignment, and similar clinical and functional results in obese patients like in non-obese patients.

METHODS

We prospectively compared the radiological, clinical, and functional results of 78 knees in 57 non-obese patients and 79 knees in 58 obese patients who underwent computer-assisted TKA. Non-obese individuals were defined as those having BMI of <30 kg/m² and obese individuals as BMI ≥30 kg/m². The degree of knee deformity was calculated by Hip - Knee - Ankle (HKA) angle and clinical and functional assessment was done using the Knee Society Score - clinical knee score and Knee Society Score - function score, respectively. All these were documented before and at 6 months, 2 year, and 5 years after TKA.

RESULTS

The outlier rate of postoperative limb alignment (HKA angle) was 8.9% in the obese group which was not significantly different (p =1.00) from that of the non-obese group (7.7%). Mean clinical knee scores were not significantly different between the non-obese and obese groups preoperatively (58.8 vs 57.4, p = 0.14) and at 6 months (92.7 vs 91, p = 0.06), 2 years (91.4 vs 90, p = 0.07), and 5 years (92.4 vs 91.3, p = 0.1) post-surgery. Similarly, mean functional scores were not significantly different between the non-obese and obese groups preoperatively (50.9 vs 49.9, p = 0.31) and at 6 months (92.7 vs 90.9, p = 0.06), 2 years (91.3 vs 92, p = 0.44), and 5 years (90.6 vs 91.1, p = 0.51) post-surgery.

CONCLUSION

Obesity has no influence on mid-term clinical, functional, and radiological results after computer navigated TKA, done by gap balancing technique.

LEVEL OF EVIDENCE

Therapeutic level II.

Effect of Coronal Alignment on 10-Year Survivorship of a Single Contemporary Total Knee Arthroplasty

Debate remains regarding the utility of mechanical axis alignment as a predictor of durability after total knee arthroplasty (TKA). Our study aimed to assess the effects of coronal alignment on implant durability, clinical outcomes, and radiographic results with a single fixed-bearing TKA design. All patients undergoing primary cemented TKA of a single design (Stryker Triathlon) from 2005–2007 with >10 years of follow-up and available pre-operative and post-operative hip–knee–ankle radiographs were included (n = 89). Radiographs were measured to determine coronal alignment and assessed for loosening. Mean preoperative mechanical axis alignment was −6° ± 6.7° (varus, range, −16°–23°), while mean post-operative alignment was −1° ± 2.7° (varus, range, −3°–15°). The aligned group was defined as knees with a post-operative mechanical axis of 0° ± 3° (n = 73) and the outlier group as those outside this range (n = 16). No patients underwent revision. Ten-year survivorship free from any reoperation was 99% and 100% in the aligned and outlier groups, respectively (p = 0.64). Knee Society scores improved significantly in both groups (p < 0.001) and did not differ at final follow-up (p = 0.15). No knees demonstrated radiographic evidence of loosening. Post-operative mechanical axis alignment within 3° of neutral was not associated with improved implant durability, clinical outcomes, or radiographic results at 10 years following primary TKA.

New Technologies in Knee Arthroplasty: Current Concepts

Total knee arthroplasty (TKA) is an effective treatment for severe osteoarthritis. Despite good survival rates, up to 20% of TKA patients remain dissatisfied. Recently, promising new technologies have been developed in knee arthroplasty, and could improve the functional outcomes. The aim of this paper was to present some new technologies in TKA, their current concepts, their advantages, and limitations. The patient-specific instrumentations can allow an improvement of implant positioning and limb alignment, but no difference is found for functional outcomes. The customized implants are conceived to reproduce the native knee anatomy and to reproduce its biomechanics. The sensors have to aim to give objective data on ligaments balancing during TKA. Few studies are published on the results at mid-term of these two devices currently. The accelerometers are smart tools developed to improve the TKA alignment. Their benefits remain yet controversial. The robotic-assisted systems allow an accurate and reproducible bone preparation due to a robotic interface, with a 3D surgical planning, based on preoperative 3D imaging or not. This promising system, nevertheless, has some limits. The new technologies in TKA are very attractive and have constantly evolved. Nevertheless, some limitations persist and could be improved by artificial intelligence and predictive modeling.

Robotic-assisted Unicompartmental knee Arthroplasty optimizes joint line restitution better than conventional surgery

Purpose

To compare joint line restoration after unicompartmental knee arthroplasty (UKA) between conventional and robotic-assisted surgery. Previous studies have shown that joint line distalization can lead to higher failure rates. The hypothesis was that robotic-assisted UKA is associated with less femoral component distalization and a precise tibial cut, which allows a more anatomical restitution of the knee joint line.

Methods

Retrospective cohort study of patients undergoing medial or lateral UKA between May 2018 and March 2020. Preoperative and postoperative radiologic assessment of the joint line was performed by two observers, using three different methods, one for tibial slope and one for tibial resection. Robotic assisted UKA and conventional UKA groups were compared.

Results

Sixty UKA were included, of which 48 (77.42%) were medial. Robotic-assisted UKA were 40 (64.52%) and 22(35.48%) were conventional

The distalization of the femoral component was higher in the conventional group despite the method of measurement used In both Weber methods, the difference was statistically different: Conventional 2.3 (0.9 to 5.6) v/s Robotic 1.5 (− 1.1 to 4.1) (p =0.0025*). A higher proportion of patients achieved a femoral component position ≤ two millimeters from the joint line using robotic-assisted UKA compared to the conventional technique .

No statistical difference between robotic-assisted and conventional UKA was found in tibial resection and slope.

Conclusion

Robotic-assisted UKA shows a better rate of joint line restoration due to less femoral component distalization than conventional UKA. No difference was found in the amount of tibial resection between groups in this study.

Level of evidence

III

Computer-Assisted Orthopedic and Trauma Surgery

BACKGROUND

There are many ways in which computer-assisted orthopedic and trauma surgery (CAOS) procedures can help surgeons to plan and execute an intervention.

METHODS

This study is based on data derived from a selective search of the literature in the PubMed database, supported by a Google Scholar search.

RESULTS

For most applications the evidence is weak. In no sector did the use of computer-assisted surgery yield any relevant clinical or functional improvement. In trauma surgery, 3D-navigated sacroiliac screw fixation has become clinically established for the treatment of pelvic fractures. One randomized controlled trial showed a reduction in the rate of screw misplacement: 0% with 3D navigation versus 20.4% with the conventional procedure und 16.6% with 2D navigation. Moreover, navigation-assisted pedicle screw stabilization lowers the misplacement rate. In joint replacements, the long-term results showed no difference in respect of clinical/functional scores, the time for which the implant remained in place, or aseptic loosening.

CONCLUSION

Computer-assisted procedures can improve the precision of certain surgical interventions. Particularly in joint replacement and spinal surgery, the research is moving away from navigation in the direction of robotic procedures. Future studies should place greater emphasis on clinical and functional results.

Accuracy of tibial component positioning in the robotic arm assisted versus conventional unicompartmental knee arthroplasty

BACKGROUND

Our study aims to determine the planned accuracy of the tibial component placement in robotic arm assisted unicompartmental knee arthroplasty (UKA) versus the conventional jig based UKA of the initial cases done in India for the first time with this particular robotic system.Materials & Methods: Study group 1 consisted of patients who underwent robotic arm (MAKO, Stryker, USA) assisted UKA. Group 2 consists of patients who underwent a standard conventional jig based (Oxford knee, Biomet, UK). Post-operative radiographs were taken to determine the Tibial Implant position and orientation which were compared to their preoperative plan respectively by two independent observers. The mean error value was obtained for both study groups respectively and compared to determine the accuracy of the post-operative tibial implant placement.

RESULTS

In the Robotic arm assisted UKA, the deviation of post-operative varus angle from preoperative planned angle was about 0.43° and post-operative Tibial slope alignment differed from preoperative plan was 0.41°. In the Conventional UKA group post-operative varus angle differed from preoperative planned angle by about 2.12° and post-operative Tibial slope alignment deviation from preoperative plan was 2.47°.

CONCLUSIONS

Robotic arm assisted system was more accurate compared to the conventional jig-based technique in achieving the planned orientation and alignment of the tibial implant in the initial learning phase of this particular Robotic System used for the first time in India.

MESH TERMS

partial knee replacement, robotic assisted surgery.

Threshold for Computer- and Robot-Assisted Knee and Hip Replacements in the English National Health Service

OBJECTIVES

To estimate threshold prices for computer- and robot-assisted knee and hip replacement.

METHODS

A lifetime cohort Markov model provided the framework for analysis. Linked primary care and inpatient hospital records informed estimates of outcomes under current practice. Outcomes were estimated under a range of hypothetical relative improvements in quality of life if unrevised and in revision risk after computer or robot-assisted surgery. Threshold prices, a price at which the net health benefit from funding the intervention would be zero, for these improvements were estimated for a cost-effectiveness threshold of £20 000 per additional quality-adjusted life-year (QALY) gained.

RESULTS

For average patient profiles under current knee and hip replacement practice, lifetime QALYs were 10.3 (9.9 to 10.7) and 11.0 (10.6 to 11.4), with costs of £6060 (£5947 to £6203) and £6506 (£6335 to £6710) for knee and hip replacement, respectively. A combined 50% relative reduction in risk of revision and 5% improvement in postoperative quality of life if unrevised would, for example, result in QALYs increasing to 10.9 (10.4 to 11.3) and 11.6 (11.2 to 12.0), and costs falling to £5880 (£5816 to £5956) and £6258 (£6149 to £6376) after knee and hip replacement, respectively. These particular improvements would have an associated threshold price of £11 182 (£10 691 to £11 721) for knee replacement and £12 134 (£11 616 to £12 701) for hip replacement. The 50% reduction in revision rate alone would have associated threshold prices of £1094 (£788 to £1488) and £1347 (£961 to £1842), and the 5% improvement in quality of life alone would have associated threshold prices of £9911 (£9476 to £10 296) and £10 578 (£10 171 to £10 982).

CONCLUSIONS

At current prices, computer- and robot-assisted knee and hip replacement will likely need to lead to improvements in patient-reported outcomes in addition to any reduction in the risk revision.

Posteromedial vertical capsulotomy selectively increases the extension gap in posterior stabilized total knee arthroplasty

PURPOSE

In total knee arthroplasty (TKA), it is important to obtain an appropriate flexion-extension gap. The extension gap is expanded by posteromedial vertical capsulotomy (PMVC). This study aimed to evaluate the increase in the extension gap by PMVC using a navigation system.

METHODS

In posterior stabilized (PS)-type TKA, PMVC was performed in 37 knees. The medial extension gap at 0° and flexion gap at 90° flexion of the knee joint using the navigation system before and after PMVC were measured.

RESULTS

The extension gap before the PMVC was 5.3 ± 2.9 mm. After PMVC, the extension gap had significantly increased to 8.0 ± 2.8 mm (p < 0.001). In addition, the flexion gap was 8.1 ± 2.7 mm before the PMVC, but it was 8.7 ± 2.8 mm after the PMVC, and the flexion gap was not enlarged (n.s.).

CONCLUSION

In PS-type TKA, it is possible to obtain selective expansion of about 2.7 mm of the extension gap by PMVC. Therefore, gap balance can be acquired by soft-tissue treatment while preserving the bone. The PMVC was a useful method for acquiring gap balance and preserving the bone stock.

LEVEL OF EVIDENCE

IV.

Stereotactic Navigation for Rectal Surgery: Comparison of 3-Dimensional C-Arm-Based Registration to Paired-Point Registration

BACKGROUND

Stereotactic navigation enables surgeons to use the preoperative CT or MRI images as a real-time "navigation map." Although stereotactic navigation has been established in neurosurgery and orthopedic surgery, whether this technology is applicable to GI tract surgery remains challenging because of tissue deformation and organ motion. A critical component of this technology is the registration that links the patient's actual body to the preoperative imaging data.

OBJECTIVE

The objective was to assess the applicability of stereotactic navigation in rectal surgery, focusing on the registration method.

DESIGN

This study was based on a prospective case series.

SETTING

The study was conducted in a single university hospital.

PATIENTS

Four patients who underwent laparoscopic rectal surgery were included.

INTERVENTIONS

Paired-point registration was performed for 2 cases, whereas 3-dimensional C-arm-based registration was performed for the other 2 cases. In addition, 3-dimensional C-arm-based registration was performed twice during the operation.

MAIN OUTCOME MEASURE

Navigation accuracy was evaluated by measuring target registration error at 8 anatomical landmarks.

RESULTS

Target registration error of the 3-dimensional C-arm-based registration group was significantly smaller than that of the paired-point registration group (median, 19.5 mm vs 54.1 mm; p < 0.001). In particular, the error of Z-axis (cranial-to-caudal direction) was significantly smaller in 3-dimensional C-arm-based registration (median, 12.4 mm vs 48.8 mm; p < 0.001). In one case in the 3-dimensional C-arm-based registration group, target registration error of the second registration became significantly smaller than that of the first registration (p = 0.008).

LIMITATIONS

This was an observational study with small sample size.

CONCLUSION

Three-dimensional C-arm-based registration could be performed with the patient in a lithotomy position with head down and lateral tilt without being affected by positional changes. Three-dimensional C-arm-based registration resulted in significantly higher navigation accuracy than paired-point registration, and its accuracy could be further improved by intraoperative re-registration.

Computer-Assisted Technologies in Arthroplasty: Navigating Your Way Today

Computer-assisted technologies that are used in arthroplasty include navigation, image-derived instrumentation (IDI), and robotics. Computer-assisted navigation improves accuracy and allows for real-time assessment of component positioning and soft-tissue tension. It is not clear whether the implementation of these technologies improves the clinical outcome of surgery. High cost and time demands have prevented the global implementation of computer-assisted technologies.

Three-dimensional assessment of lower limb alignment: Reference values and sex-related differences

BACKGROUND

Three-dimensional (3D) preoperative planning and assisted surgery is increasingly popular in deformity surgery and arthroplasty. Reference ranges for 3D lower limb alignment are needed as a prerequisite for standardized analysis of alignment and preoperative planning in 3D, but are not yet established.

METHODS

On 60 3D bone models of the lower limbs based on computed tomography data, fifteen parameters per leg were assessed by standardized validated 3D analysis. Distribution parameters and differences between sexes were evaluated. Reference values were generated by adding/subtracting one standard deviation from the mean.

RESULTS

Women had a significantly lower mean mechanical lateral distal femoral angle compared with men (86.4 ± 2.1° vs. 87.8 ± 2.0°; P < .05) and significantly lower mean joint line convergence angle (-2.5 ± 1.4° vs. -1.3 ± 1.2; P < .01), but higher mean hip knee ankle angle (178.9 ± 1.9° vs. 177.8 ± 2.3°; P < .05) and mean femoral torsion (18.2 ± 9.5° vs. 13.2 ± 6.4°; P < .05), resulting in a tendency towards valgus alignment and vice versa for men. Differences in mean medial proximal tibial angle were not significant. The mean mechanical axis deviation from the tibial knee joint center was 6.9 ± 7.3 mm medial and 1.4 ± 16.1 mm ventral without significant differences between sexes.

CONCLUSIONS

We describe total and sex-related reference ranges for all alignment relevant axes and joint angles of the lower limb. There are sex-related differences in certain alignment parameters, which should be considered in analysis and surgical planning.

An umbrella review comparing computer-assisted and conventional total joint arthroplasty: quality assessment and summary of evidence

Background

Systematic reviews (SRs) of computer-assisted (CA) total knee arthroplasty (TKA) and total hip arthroplasty (THA) report conflicting evidence on its superiority over conventional surgery. Little is known about the quality of these SRs; variability in their methodological quality may be a contributing factor. We evaluated the methodological quality of all published SRs to date, summarized and examined the consistency of the evidence generated by these SRs.

Methods

We searched four databases through December 31, 2018. A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR 2) was applied to assess the methodological quality. Evidence from included meta-analyses on functional, radiological and patient-safety outcomes was summarized. The corrected covered area was calculated to assess the overlap between SRs in including the primary studies.

Results

Based on AMSTAR 2, confidence was critically low in 39 of the 42 included SRs and low in 3 SRs. Low rating was mainly due to failure in developing a review protocol (90.5%); providing a list of excluded studies (81%); accounting for risk of bias when discussing the results (67%); using a comprehensive search strategy (50%); and investigating publication bias (50%). Despite inconsistency between SR findings comparing functional, radiological and patient safety outcomes for CA and conventional procedures, most TKA meta-analyses favored CA TKA, whereas most THA meta-analyses showed no difference. Moderate overlap was observed among TKA SRs and high overlap among THA SRs.

Conclusions

Despite conclusions of meta-analyses favoring CA arthroplasty, decision makers adopting this technology should be aware of the low confidence in the results of the included SRs. To improve confidence in future SRs, journals should consider using a methodological assessment tool to evaluate the SRs prior to making a publication decision.

Improved mediolateral load distribution without adverse laxity pattern in robot-assisted knee arthroplasty compared to a standard manual measured resection technique

PURPOSE

Robot-assisted total knee arthroplasty (rTKA) remains in its infancy, is expensive but offers the promise of improved kinematic performance through precise bone cuts, with minimal soft tissue disruption, based on pre-resection soft tissue behaviour. This cadaveric study examined load transfer, soft tissue performance and radiographic indices for conventional (sTKA) versus rTKA. The null hypothesis was there would be no difference between the two modes of implantation.

METHODS

Whole (ten) cadaveric limbs were randomised to receive either robotic (rTKA, N = 5) or conventional measured resection (sTKA, N = 5) knee arthroplasty. Laxity patterns were established using validated fixed sensors (Verasense) with manual maximum displacement for six degrees of freedom. Tibiofemoral load and contact points were determined dynamically using remote sensor technology for medial and lateral compartments through a functional arc of motion (0-110 degrees of motion). Final component position was assessed using pre- and post-implantation CT.

RESULTS

No significant intergroup differences for laxity were found (n.s.). The rTKA group exhibited consistently balanced mediolateral load throughout the full arc with significantly reduced overall total load across the joint (for distinct points of measurement, p < 0.05). Despite using flexion-extension and mediolateral gap balancing with measured resection, the sTKA group failed to achieve balance in at least three points of the flexion arc. Post-operative CT confirmed satisfactory component alignment with no significant differences for positioning between the two groups.

CONCLUSION

This work found improved load sharing for rTKA when compared to conventional surgery for same donor knees. Laxity and CT determined final component positioning was not significantly different. The work supports the contention that robot-assisted TKA delivers improved tibiofemoral load sharing in time zero studies under defined conditions but such offers the promise of improved clinical performance and reduced implant wear.

Deep segmentation leverages geometric pose estimation in computer-aided total knee arthroplasty

Knee arthritis is a common joint disease that usually requires a total knee arthroplasty. There are multiple surgical variables that have a direct impact on the correct positioning of the implants, and an optimal combination of all these variables is the most challenging aspect of the procedure. Usually, preoperative planning using a computed tomography scan or magnetic resonance imaging helps the surgeon in deciding the most suitable resections to be made. This work is a proof of concept for a navigation system that supports the surgeon in following a preoperative plan. Existing solutions require costly sensors and special markers, fixed to the bones using additional incisions, which can interfere with the normal surgical flow. In contrast, the authors propose a computer-aided system that uses consumer RGB and depth cameras and do not require additional markers or tools to be tracked. They combine a deep learning approach for segmenting the bone surface with a recent registration algorithm for computing the pose of the navigation sensor with respect to the preoperative 3D model. Experimental validation using ex-vivo data shows that the method enables contactless pose estimation of the navigation sensor with the preoperative model, providing valuable information for guiding the surgeon during the medical procedure.

Individualized alignment in total knee arthroplasty using image-based robotic assistance : Video article

Introduction

Over the past decades many innovations were introduced in total knee arthroplasty (TKA) focusing on implant longevity and higher procedural precision; however, there are still a high number of dissatisfied patients. It was reported that better anatomical alignment may result in improved patient outcome; however, current technologies have limitations to achieve this. The aim of this video article is to describe the technique of individualized alignment in TKA with the use of image-based robotic assistance.

Methods

The technology is based on an individual patient knee model computed from segmented computed tomography (CT) scans. A preoperative planning of prosthesis position is conducted following the principle of kinematic alignment. Intraoperatively the soft tissue envelope is recorded and the computer predicts the gap balance based on the virtual planning. The prosthesis position is then adapted to achieve balanced gaps and to avoid soft tissue release. This technique is shown in a cadaver operation and clinical examples of two patients are described.

Results

With the combination of anatomically oriented prosthesis positioning and minor adaptations with respect to the soft tissue, an individualized alignment is achieved with reduced need of soft tissue release. The robotic-assisted surgery guarantees a precise implementation of the planning. The initial experience showed a promising outcome in short-term follow-up.

Video online

The online version of this article (10.1007/s00132-018-3637-1) contains a video on patient individualized alignment in total knee arthroplasty. The article and video are available in the electronic full text archive at SpringerMedizin.de under http://www.springermedizin.de/der-orthopaede. The video can be found at the end of the article as supplementary material.

An Experienced Surgeon Can Meet or Exceed Robotic Accuracy in Manual Unicompartmental Knee Arthroplasty

BACKGROUND

Reports in the literature indicate that implant placement is more accurate with robotic-assisted unicompartmental knee arthroplasty (UKA); however, these studies have not always accounted for surgeon experience. The purpose of the present study was to compare the accuracy of tibial component alignment in UKA between an experienced high-volume surgeon and the published data on robotic-assisted surgery.

METHODS

The radiographs made before and after 128 consecutive medial UKAs performed manually by a single surgeon using a cemented fixed-bearing implant were reviewed. Native tibial and tibial implant slope and varus alignment of the tibial implant were measured on preoperative and postoperative lateral and anteroposterior radiographs, respectively. The percentages of knees in which the postoperative measurements were within preoperative targets and the root mean square (RMS) error rates between the planned and achieved targets were compared with published robotic-assisted-UKA data.

RESULTS

In the present study, the proportion of manual UKAs in which the tibial component alignment was within the preoperative target was 66% (85 of 128), which exceeded published values in a study comparing robotic (58%) with manual (41%) UKA. The RMS error for tibial component alignment in the present study (1.48°) was less than published RMS error rates for robotic UKAs (range, 1.8° to 5°). Fifty-eight percent (74) of the 128 study UKAs were within the surgeon's preoperative goal for tibial slope, which was closer to the published value of 80% for robotic UKAs than is the published rate of 22% for manual UKAs. The RMS error for tibial slope in the study UKAs (1.50°) was smaller than the published RMS error rates for tibial slope in robotic UKAs (range, 1.6° to 1.9°).

CONCLUSIONS

Accurate implant alignment is important in UKA. In this study, an experienced surgeon achieved or exceeded robotic accuracy of tibial implant alignment in UKA. However, the relationship between implant position and patient outcomes is unknown, and a consensus on ideal surgical targets for optimal implant survivorship has yet to be established.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Computer-Aided Orthopedic Surgery: Incremental Shift or Paradigm Change?

Computer-aided orthopedic surgery (CAOS) is now about 25 years old. Unlike neurosurgery, computer-aided surgery has not become the standard of care in orthopedic surgery. In this paper, we provide the technical and clinical context raised by this observation in an attempt to elucidate the reasons for this state of affairs. We start with a brief outline of the history of CAOS, review the main CAOS technologies, and describe how they are evaluated. We then identify some of the current publications in the field and present the opposing views on their clinical impact and their acceptance by the orthopedic community worldwide. We focus on total knee replacement surgery as a case study and present current clinical results and contrasting opinions on CAOS technologies. We then discuss the challenges and opportunities for research in medical image analysis in CAOS and in musculoskeletal radiology. We conclude with a suggestion that while CAOS acceptance may be more moderate than that of other fields in surgery, it still has a place in the arsenal of useful tools available to orthopedic surgeons.

Robotic-assisted unicompartmental knee replacement offers no early advantage over conventional unicompartmental knee replacement

PURPOSE

Unicompartmental knee arthroplasty (UKA) is effective for treating degenerative joint disease in a single compartment. Robotic-arm-assisted arthroplasty (RAA) has gained popularity and has theoretical benefits of improved outcomes over conventional (CONV) UKA due to the technical precision of bone preparation. This study compares the short-term clinical outcomes, including survivorship and patient-reported functional outcomes, for a series of medial UKAs performed with RAA and CONV.

METHODS

One hundred seventy-six consecutive fixed-bearing medial UKAs were retrospectively identified with a minimum follow-up of 2 years. One hundred and eighteen CONV and 58 RAA were performed. Pre- and post-operative SF12, WOMAC, and KSS Functional Questionnaires were available for all patients.

RESULTS

At 2 years, both groups improved in all functional outcomes, with no significant difference between the RAA and CONV cohorts. However, the RAA cohort had a significantly longer operative time (p < 0.001) and a higher early revision rate than the CONV group (7 [12.0%] vs. 7 [6.8%]; p < 0.05).

CONCLUSIONS

These results demonstrate that at short-term follow-up of 2 years, RAA was not superior to CONV in terms of functional scores and instead was associated with greater operative time and cost and lower survivorship. Therefore, at this time usage of RAA in UKA is not recommended compared to conventional UKA. Longer term studies are necessary to draw conclusions about the overall outcomes of RAA compared to CONV.

LEVEL OF EVIDENCE

III.

Augmented Reality in Orthopedics: Current State and Future Directions

Augmented reality (AR) comprises special hardware and software, which is used in order to offer computer-processed imaging data to the surgeon in real time, so that real-life objects are combined with computer-generated images. AR technology has recently gained increasing interest in the surgical practice. Preclinical research has provided substantial evidence that AR might be a useful tool for intra-operative guidance and decision-making. AR has been applied to a wide spectrum of orthopedic procedures, such as tumor resection, fracture fixation, arthroscopy, and component's alignment in total joint arthroplasty. The present study aimed to summarize the current state of the application of AR in orthopedics, in preclinical and clinical level, providing future directions and perspectives concerning potential further benefits from this technology.

Making the transition from traditional to robotic-arm assisted TKA: What to expect? A single-surgeon comparative-analysis of the first-40 consecutive cases

Objective/methods

We compared short-term outcomes following 40 traditional, cemented total knee arthroplasty (TKA) to the first 40 cemented robotic-arm assisted TKA (raTKA) and analyzed the learning curve for raTKA.

Results

LOS was longer for traditional TKA compared to raTKA (1.92 vs. 1.27days, p < 0.0001). There was no difference in surgical time between the second 20 raTKA and all traditional TKA cases (81.1 vs. 78.3 mins, p = 0.254). raTKA patients had improved 90-day ROM (+3.8° vs. -8.7°, p < 0.05) but comparable complications rates, Knee Society Scores, and patient-reported outcomes at all timepoints.

Conclusion

Despite comparable outcomes, the learning curve for raTKA appeared to progress rapidly.

Stereotactic Pelvic Navigation With Augmented Reality for Transanal Total Mesorectal Excision

INTRODUCTION

Technical difficulty and unfamiliar surgical anatomy are the main challenges in transanal total mesorectal excision. Precise 3-dimensional real-time image guidance may facilitate the safety, accuracy, and efficiency of transanal total mesorectal excision.

TECHNIQUE

A preoperative CT was obtained with 10 skin fiducials and further processed to emphasize the border of the anatomical structure by 3-dimensional modeling and pelvic organ segmentation. A forced sacral tilt by placing a 10-degree wedge under the patient's sacrum was induced to minimize pelvic organ movement caused by lithotomy position. An optical navigation system with cranial software was used. Preoperative CT images were loaded into the navigation system, and patient tracker was mounted onto the iliac bone. Once the patient-to-image paired point registration using skin fiducials was completed, the laparoscopic instrument mounted with instrument tracker was calibrated for instrument tracking. After validating the experimental setup and process of registration by navigating laparoscopic anterior resection, stereotactic navigation for transanal total mesorectal excision was performed in the low rectal neuroendocrine tumor.

RESULTS

The fiducial registration error was 1.7 mm. The accuracy of target positioning was sufficient at less than 3 mm (1.8 ± 0.9 mm). Qualitative assessment using a Likert scale was well matched between the 2 observers. Of the 20 scores, 19 were judged as 4 (very good) or 5 (excellent). There was no statistical difference between mean Likert scales of the abdominal or transanal landmarks (4.4 ± 0.5 vs 4.3 ± 1.0, p = 0.965).

CONCLUSIONS

Application of an existing navigation system to transanal total mesorectal excision for a low rectal tumor is feasible. The acceptable accuracy of target positioning justifies its clinical use. Further research is needed to prove the clinical need for the procedure and its impact on clinical outcomes.

Knee replacement

Knee replacement surgery is one of the most commonly done and cost-effective musculoskeletal surgical procedures. The numbers of cases done continue to grow worldwide, with substantial variation in utilisation rates across regions and countries. The main indication for surgery remains painful knee osteoarthritis with reduced function and quality of life. The threshold for intervention is not well defined, and is influenced by many factors including patient and surgeon preference. Most patients have a very good clinical outcome after knee replacement, but multiple studies have reported that 20% or more of patients do not. So despite excellent long-term survivorship, more work is required to enhance this procedure and development is rightly focused on increasing the proportion of patients who have successful pain relief after surgery. Changing implant design has historically been a target for improving outcome, but there is greater recognition that improvements can be achieved by better implantation methods, avoiding complications, and improving perioperative care for patients, such as enhanced recovery programmes. New technologies are likely to advance future knee replacement care further, but their introduction must be regulated and monitored with greater rigour to ensure patient safety.

The effectiveness of robotic hip and knee arthroplasty on patient-reported outcomes: A systematic review and meta-analysis

PURPOSE

The purpose of the study is to determine the effectiveness of semi-active and active robotic hip and knee arthroplasty on post-operative patient-reported outcomes of function, pain, quality of life and satisfaction with surgery.

METHODS

PubMed, Medline, Embase and CENTRAL were searched. Included were comparative studies investigating the effectiveness of semi-active or active robotic hip or knee arthroplasty compared to any other surgical intervention on function, pain, quality of life and satisfaction with surgery. Risk of bias and the strength of the evidence were assessed using the Downs and Black tool and the GRADE system, respectively. Relative risks, mean differences and 95% CI were calculated using random-effects models.

RESULTS

Fourteen studies involving 1342 patients were included. All studies compared robotic to conventional surgery, with active robotic surgery evaluated in total hip or knee arthroplasty and semi-active robotic surgery in total hip or unicompartmental knee arthroplasty. Most studies presented some risk of bias, and the strength of evidence was rated as low to very low quality. Random-effects meta-analyses showed that post-operative functional outcomes were comparable between active robotic and conventional total hip and knee arthroplasty at the short-, medium- and long-term follow-up. No significant difference in pain, quality of life and satisfaction with surgery were reported in individual studies.

CONCLUSIONS

This systematic and meta-analyses indicates that functional outcomes for patients undergoing active robotic total hip and knee arthroplasty were comparable to conventional surgery. Whether semi-active or active robotic hip or knee arthroplasty is effective in improving post-operative pain, quality of life and satisfaction with surgery is unclear. PROSPERO Registration Number: CRD42017059932.

Patient reported and clinical outcomes of robotic-arm assisted unicondylar knee arthroplasty: Minimum two year follow-up

Background

Unicompartmental knee arthroplasty (UKA) originated in the 1950's. There have been many enhancements to the implants and the technique, improving the precision and accuracy of this challenging operation. Specifically for Robotic Arm Interactive Orthopedic System (Rio; Mako Stryker, Fort Lauderdale, FL), there are many studies reporting clinical outcomes, but our search offered nothing regarding patient reported outcomes using validated surveys.

Methods

Patients with onlay tibial components presenting for routine follow-up of robotic-arm assisted UKA performed between May 2009 and September 2013 were invited to participate. Four joints had simultaneous patella femoral resurfacing. Knee Injury and Osteoarthritis Outcomes Score (KOOS) and the 2011 Knee Society Scores were collected. Radiographic evidence of osteoarthritis in the non-operative knee compartments was documented.

Results

Eighty-one patients presented for follow-up and consented to participate. Mean follow up was 54 months. Mean patient reported KOOS activities of daily living and pain scores were each 90. Knee Society 2011 mean objective score was 96 and mean function score 81. There was one revision to total knee at 40 months post-op for pain after injury. Seventy-seven percent reported their knee always felt "Normal", 20% sometimes, and only 3% reported that it never felt normal.

Conclusion

Literature on UKA failure rates suggests that UKA may be a less forgiving procedure than total knee arthroplasty. Robotic-arm assisted surgery is reported to improve the accuracy of implant placement. Based on our prospectively collected positive patient outcomes, the authors have achieved good results from performing robotic-arm assisted UKA on select patients.

Robotic Arm-Assisted Total Knee Arthroplasty

BACKGROUND

Robotic arm-assisted total knee arthroplasty (RATKA) has a number of potential advantages. Therefore, in order to more comprehensively assess this technology, we reviewed the (1) accuracy and precision; (2) soft-tissue protection; (3) patient satisfaction; (4) learning curve; and (5) its other potential benefits.

METHODS

A literature review was conducted using PubMed search database for studies reporting clinical outcomes, cadaver results, radiographic outcomes, surgeon experience, and robotic accuracy. Forty articles were included for the final analysis.

RESULTS

Advantages of RATKA may include greater component accuracy and precision, soft-tissue protection, increased patient satisfaction, a short learning curve, optimal ergonomic design, and less surgeon and surgical team fatigue. The aforementioned advantages might help improve clinical, surgical, and patient-reported outcomes.

CONCLUSION

Although there are a number of studies that highlight the potential advantages of RATKA, most of these studies report of short-term outcomes. It is hoped that longer term studies will continue to support the use of this technology in providing higher patient satisfaction and other clinical outcomes.

Pros and Cons: A Balanced View of Robotics in Knee Arthroplasty

In both unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA), compared with conventional techniques robotic technology has been shown to optimize the precision of bone preparation and component alignment, reducing outliers and increasing the percentage of components aligned within 2° or 3° of the target goal. In addition, soft tissue balance can be quantified through a range of motion in UKA and TKA using the various robotic technologies available. Although the presumption has been that the improved alignment associated with robotics will improve function and implant durability, there are limited data to support that notion. Based on recent and emerging data, it may be unreasonable to presume that robotics is necessary for both UKA and TKA. In fact, despite improvements in various proxy measures, the precision of robotics may be more important for UKA than TKA, although if system costs and surgical efficiencies continue to improve, streamlining perioperative processes, reducing instrument inventory, and achieving comparable outcomes in TKA may be a reasonable goal of robotic surgery.

Unicompartmental knee arthroplasty: Current indications, technical issues and results

An age younger than 60 years, a body weight of 180 lb (82 kg) or more, performing heavy work, having chondrocalcinosis and having exposed bone in the patellofemoral (PF) joint are not contraindications for unicompartmental knee arthroplasty (UKA).Severe wear of the lateral facet of the PF joint with bone loss and grooving is a contraindication for UKA.Medial UKA should only be performed in cases of severe osteoarthritis (OA) as shown in pre-operative X-rays, with medial bone-on-bone contact and a medial/lateral ratio of < 20%.The post-operative results of UKA are generally good. Medium-term and long-term studies have reported acceptable results at 10 years, with implant survival greater than 95% for UKAs performed for medial OA or osteonecrosis and for lateral UKA, especially when fixed-bearing implants are used.When all implant-related re-operations are considered, the 10-year survival rate is 94%, and the 15-year survival rate is 91%.Aseptic loosening is the principal failure mechanism in the first few years in mobile-bearing implants, whereas OA progression causes most failures in later years in fixed-bearing implants.The overall complication rate and the comprehensive re-operation rate are comparable in both mobile bearings and fixed bearings.The survival likelihood of the all-polyethylene UKA implant is similar to that of metal-backed modular designs for UKA.Notable cost savings of approximately 50% can be achieved with an outpatient UKA surgery protocol. Outpatient surgery for UKA is efficacious and safe, with satisfactory clinical results thus far. Cite this article: EFORT Open Rev 2018;3:363-373. DOI: 10.1302/2058-5241.3.170048.

The femoral component alignment resulting from spacer block technique is not worse than after intramedullary guided technique in medial unicompartimental knee arthroplasty

PURPOSE

Although the spacer block technique has been recommended for the implantation of unicompartmental knee arthroplasty (UKA), there is still a lack of data concerning the resulting component positioning.

METHODS

This retrospective study included 193 consecutive patients who had undergone medial UKA using the spacer technique. On the basis of the postoperative long standing radiographs, the coronal component alignment was determined in relation to the mechanical axes and the sagittal component alignment in relation to the anatomical axes of the tibia and femur. The coronal alignment of the femoral component was determined through post hoc 3D planning with the CAD data projected onto the radiograph.

RESULTS

The angle of the tibial component was on the average 2.3° ± 2.8° in varus, the femoral component on the average 2.6° ± 3.7° in varus. Only 4 implants (2%) were outside an assumed tolerance range of 10° varus-10° valgus. A tilting from the femoral to the tibial component of more than 10° was observed in 8 cases (4%). A valgus positioning of the tibial component was followed by a valgus alignment of the femoral component (R = - 0.194, p = 0.007). An increased posterior slope of the tibial component led to an extended positioning of the femoral component (R = - 0.230, p = 0.001).

CONCLUSIONS

The spacer block technique produces results comparable to the intramedullary guided technique. However, the precision is low and outlier frequent. Due to the possibility of transferring a tibial malalignment to a femoral malalignment, even greater attention should be paid to the precision of tibial resection.

Advances in Patellofemoral Arthroplasty

PURPOSE OF REVIEW

To describe current indications, implants, economic benefits, comparison to TKA, and functional and patient-reported outcomes of patellofemoral arthroplasty.

RECENT FINDINGS

Modern onlay implants and improved patient selection have allowed for recent improvements in short- and long-term outcomes after patellofemoral joint replacement surgery. Patellofemoral arthroplasty has become an increasingly utilized technique for the successful treatment of isolated patellofemoral arthritis. Advances in patient selection, implant design, and surgical technique have resulted in improved performance and longevity of these implants. Although short- and mid-term data for modern patellofemoral arthroplasties appear promising, further long-term clinical studies are needed to evaluate how new designs and technologies will affect patient outcomes and long-term implant performance.

Technology-Assisted Hip and Knee Arthroplasties: An Analysis of Utilization Trends

BACKGROUND

Robotic and computer navigation technology is available to surgeons for use in hip and knee arthroplasties to increase the precision of component placement. However, they do add significant costs to these procedures, and the long-term clinical outcomes and value of technology assistance for joint replacement remain unclear.

METHODS

We identified 321,522 patients in Medicare Severity Diagnosis Related Groups 469 and 470 who underwent primary total hip arthroplasty (N = 133,472) or primary total or unicompartmental knee arthroplasty (N = 188,050) between 2008 and 2015 in the New York Statewide Planning and Research Cooperative System (SPARCS).

RESULTS

Among all total joint arthroplasties performed during this period, technology assistance was used in 5.1% of cases. Technology assistance was more common for knee (7.3%) than hip (1.9%) arthroplasty (P < .001). The proportion of cases using technology assistance grew each year, increasing from 2.8% (knee 4.3% and hip 0.5%) in 2008 to 8.6% (knee 11.6% and hip 5.2%) in 2015 (P trend <.001). The proportion of hospitals and surgeons using robotic assistance also increased during the study period, increasing from 16.2% of hospitals and 6.2% of surgeons in 2008 to 29.2% of hospitals and 17.1% of surgeons in 2015 (P trend <.001 for both). Technology was more likely to be used for patients with private insurance (5.9%) compared with Medicare (4.7%, P < .001) or Medicaid (2.2%, P < .001), and for patients at high-volume (6.9%, P < .001) or very high-volume (6.1%, P < .001) as compared with low-volume (2.7%) hospitals.

CONCLUSION

Technology assistance has become increasingly used by orthopedic surgeons for hip and knee arthroplasties, however, adoption has not been uniform.