Clinical and radiological outcomes of robotic-assisted versus conventional total knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials

A comparative study of early postoperative pain: robotic-assisted versus conventional total knee arthroplasty

PURPOSE

While robotic-assisted total knee arthroplasty (RA-TKA) has demonstrated improved surgical precision, its impact on early postoperative pain management remains unclear. This study compared early postoperative pain outcomes between RA-TKA and conventional TKA (C-TKA).

METHODS

In this retrospective study, 230 consecutive patients (309 knees) who underwent primary TKA were analyzed: 143 patients (181 knees) in the C-TKA group and 87 patients (128 knees) in the RA-TKA group. Pain scores at rest and during movement were assessed using the Numerical Pain Rating Scale for 72 h postoperatively. Secondary outcomes included opioid consumption and length of hospital stay.

RESULTS

While pain scores at rest showed no significant differences between groups, RA-TKA patients reported significantly lower pain scores during movement at 24 h post-surgery (p = 0.023). The RA-TKA group demonstrated significantly reduced opioid consumption during the first 48 postoperative hours (p = 0.001 for 0-24 h; p = 0.03 for 24-48 h) and shorter length of hospital stay (p = 0.011). Subgroup analysis of unilateral procedures showed similar advantages in the RA-TKA group.

CONCLUSION

RA-TKA was associated with reduced pain during movement, decreased opioid consumption, and shorter hospital stay in the early postoperative period compared to C-TKA.

Navigated versus conventionally instrumented total knee arthroplasty techniques: No difference in functional alignment or balance

PURPOSE

Much debate exists about the superiority of navigated versus conventional instrumentation for achieving optimal balance and alignment during total knee arthroplasty (TKA). Recent registry data indicate no long-term survivorship benefit for TKAs performed using technology assistance, despite the added resource and financial costs. However, outcome comparisons are confounded by varying surgeon techniques and targets for ideal balance and alignment. This study aimed to investigate alignment or balance outcome differences between navigated and conventionally instrumented TKAs performed using an identical operative sequence and alignment strategy.

METHODS

Fifty navigated and 50 conventionally instrumented primary TKAs, using an identical inverse kinematic alignment strategy, were included. Navigation equipment was used intraoperatively to 'post-cut' record the conventionally instrumented TKAs. Intraoperative balance, range, and alignment; and post-operative radiographic accuracy for restoration of constitutional alignment were compared.

RESULTS

Forty-nine navigated and 49 conventionally instrumented TKAs were compared (n = 2 excluded due to inadequate radiographs). No preoperative demographic or deformity severity differences existed. No intraoperative balance, range or alignment difference existed. Neither technique was more accurate for restoration of constitutional alignment.

CONCLUSION

Whilst large registry data may be confounded by uncaptured variables such as surgeon balancing techniques or surgeon alignment strategy preferences, this study found no alignment or balance differences between navigated versus conventionally instrumented TKA techniques for a surgeon and technique-controlled study. Although the increased resources necessary for technology assistance are not justified by this study, further studies may identify significance using larger samples or comparison of alternative outcomes.

LEVEL OF EVIDENCE

Level II.

Patient-specific instrumentation improved clinical outcome and implant survival but is not superior compared to conventional total knee arthroplasty: Ten years follow-up of a multicenter double-blind randomized controlled trial

PURPOSE

Patient-specific instrumentation (PSI) is a commonly used technique designed to improve mechanical alignment in total knee arthroplasty (TKA) and was therefore believed to lead to better clinical outcome and implant survival rates compared with conventional instruments (CIs). To date, long-term results comparing these two techniques are not available.

METHODS

This study is a 10-year follow-up of a previous double-blind multicenter randomized controlled trial where PSI was compared with CI. Patients with osteoarthritis of the knee who were candidates for TKA were included. Exclusion criteria were metal near the knee-, ankle- or hip joint, patients with contra-indications for a magnetic resonance imaging (MRI) scan and patients who had previous knee surgery (except arthroscopic meniscectomy). Clinical outcomes were assessed using patient-reported outcome measures (PROMs), and the analysis was performed with a general linear mixed model for repeated measurements. Kaplan-Meier curves were used to compare revision rates. X-rays were obtained and examined by two individual reviewers for any signs of loosening of the components.

RESULTS

At a mean follow-up of 10.1 (SD 0.1) years, 129 patients (loss to follow-up 23%) were analysed in this trial. No statistically significant difference between the two groups were found for any of the PROMs and revision rates were comparable, six in the PSI group and three in the CI group (p = 0.29). Two X-rays in the PSI group showed a radiolucent line of the femoral component.

CONCLUSION

At 10-year follow-up, PSI does not lead to better clinical outcome or survival of the prosthesis compared with CI.

LEVEL OF EVIDENCE

Level 1.

Preliminary Study on Patient-Reported Pain and Early Functional Outcomes of Robotic Arm-Assisted Versus Jig-Based Total Knee Arthroplasty

PURPOSE

Robotic knee replacement has gained widespread popularity globally, although the functional outcomes for patients, in comparison to traditional surgery, remain uncertain. This study aimed to compare patient-reported pain levels and early functional outcomes following robotic arm-assisted total knee arthroplasty (RTKA) and conventional jig-based TKA. The focus was on evaluating differences in pain relief, functional recovery, and postoperative scores at three, six, and 12 months.

METHODS

A retrospective analysis was conducted on 240 patients with tri-compartmental osteoarthritis who underwent primary TKA between January 2021 and September 2022. Of these, 120 received RTKA, and 120 underwent conventional TKA. Patients were assessed preoperatively and postoperatively at three, six, and 12 months using the Western Ontario McMaster University Osteoarthritis Index (WOMAC), Hospital for Special Surgery (HSS) Knee Rating Scale, and Oxford Knee Score (OKS). Statistical analyses, including t-tests, Mann-Whitney U tests, and Friedman analysis of variance (ANOVA), were performed to compare differences in outcomes.

RESULTS

Both the RTKA and conventional TKA groups exhibited significant functional improvements from baseline across all evaluated measures. When comparing absolute postoperative scores, there were no significant differences in WOMAC and OKS scores between the groups at three, six, and 12 months (p-values: 0.198, 0.206, and 0.446 for WOMAC; 0.465, 0.117, and 1.0 for OKS). However, the RTKA group had significantly higher HSS scores at 3 months (p = 0.032) and showed a significantly greater improvement in HSS from baseline at three months (p = 0.004) and in OKS from baseline at six months (p = 0.037). By 12 months, no notable differences in functional outcomes were observed between the groups. Patient satisfaction was high in both groups, with a trend toward greater satisfaction in the RTKA group regarding pain relief and daily activities.

CONCLUSIONS

RTKA provided significant improvements in early functional outcomes, as evidenced by the higher HSS score at three months and the greater improvement in OKS at six months compared to baseline. However, by 12 months, no significant differences were observed between RTKA and conventional jig-based TKA in terms of functional outcomes and pain relief. These findings suggest that while robotic technology may enhance early recovery, its long-term benefits remain uncertain. Further research with extended follow-up periods especially in personalized alignment philosophies is necessary to evaluate the potential advantages of robotic assistance in long-term functional outcomes and implant longevity.

Robotic total knee arthroplasty safely reduces length of stay in an Asian public healthcare system

Aims

Around the world, the emergence of robotic technology has improved surgical precision and accuracy in total knee arthroplasty (TKA). This territory-wide study compares the results of various robotic TKA (R-TKA) systems with those of conventional TKA (C-TKA) and computer-navigated TKA (N-TKA).

Methods

This is a retrospective study utilizing territory-wide data from the Clinical Data Analysis and Reporting System (CDARS). All patients who underwent primary TKA in all 47 public hospitals in Hong Kong between January 2021 and December 2023 were analyzed. Primary outcomes were the percentage use of various robotic and navigation platforms. Secondary outcomes were: 1) mean length of stay (LOS); 2) 30-day emergency department (ED) attendance rate; 3) 90-day ED attendance rate; 4) 90-day reoperation rate; 5) 90-day mortality rate; and 6) surgical time.

Results

A total of 8,492 knees from 7,746 patients were included in the study. Overall robotic use had risen to 20.4% (2023 Q3 to Q4: 355/1,738) by the end of 2023, with Mako being the most popular at 10.3% (179/1,738). R-TKA had the shortest mean LOS compared with N-TKA and C-TKA (5.5 vs 6.3 and 7.1 days, respectively; p < 0.001). Only Mako (9.7%) demonstrated reduced 90-day ED attendance compared to C-TKA (13.1%; p = 0.009), Cori/Navio (15.0%; p = 0.005), and Rosa (16.4%; p < 0.001). No differences in 90-day reoperation rate and mortality were observed between all groups. Mean surgical times were longer in R-TKA groups by 20.6 minutes (p < 0.001).

Conclusion

R-TKA use has increased in recent years, and has been shown to reduce hospital stay despite having a slightly longer surgical time, proving a promising candidate to alleviate the burden on healthcare systems. Individual differences between R-TKA systems contributed to variable clinical outcomes.

Exploring artificial intelligence in orthopaedics: A collaborative survey from the ISAKOS Young Professional Task Force

Purpose

Through an analysis of findings from a survey about the use of artificial intelligence (AI) in orthopaedics, the aim of this study was to establish a scholarly foundation for the discourse on AI in orthopaedics and to elucidate key patterns, challenges and potential future trajectories for AI applications within the field.

Methods

The International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Young Professionals Task Force developed a survey to collect feedback on issues related to the use of AI in the orthopaedic field. The survey included 26 questions. Data obtained from the completed questionnaires were transferred to a spreadsheet and then analyzed.

Results

Two hundred and eleven orthopaedic surgeons completed the survey. The survey encompassed responses from a diverse cohort of orthopaedic professionals, predominantly comprising males (92.9%). There was wide representation across all geographic regions. A notable proportion (52.1%) reported uncertainty or lack of differentiation among AI, machine learning and deep learning (47.9%). Respondents identified imaging-based diagnosis (60.2%) as the primary field of orthopaedics poised to benefit from AI. A considerable proportion (25.1%) reported using AI in their practice, with primary reasons including referencing scientific literature/publications (40.3%). The vast majority expressed interest in leveraging AI technologies (95.3%), demonstrating an inclination towards incorporating AI into orthopaedic practice. Respondents indicated specific areas of interest for further study, including prediction of patient outcomes after surgery (30.8%) and image-based diagnosis of osteoarthritis (28%).

Conclusions

This survey demonstrates that there is currently limited use of AI in orthopaedic practice, mainly due to a lack of knowledge about the subject, a lack of proven evidence of its real utility and high costs. These findings are in accordance with other surveys in the literature. However, there is also a high level of interest in its use in the future, in increased study and further research on the subject, so that it can be of real benefit and make AI an integral part of the orthopaedic surgeon's daily work.

Level of Evidence

Level IV, survey study.

Evidence Versus Frenzy in Robotic Total Knee Arthroplasty: A Systematic Review Comparing News Media Claims to Randomized Controlled Trial Evidence

BACKGROUND

Robotic total knee arthroplasty (rTKA) has garnered increasing attention in recent years, both clinically and in the media. The purpose of this study was to compare the volume of and messaging in published randomized controlled trials (RCTs) versus media reports on the topic of rTKA.

METHODS

This was a systematic review of RCTs and media articles on rTKA. PubMed, Embase, and MEDLINE were searched for RCTs; Factiva was searched for media articles. The number of publications of each type per year was recorded. Media articles were classified on the basis of their primary information source, their general tone toward rTKA, and the benefits and drawbacks of rTKA discussed. The volume, tone, and specific messaging around rTKA were compared between media articles and RCTs.

RESULTS

Fifteen RCTs and 460 media articles, published between 1991 and 2023, were included. The rates of both publication types increased over time, with more rapid increases in recent years. Ninety-five percent of media publications highlighted at least 1 benefit of rTKA. The most commonly cited benefits were more precise implant positioning (82.6%) and faster recovery (28.7%). Fewer than 7% of media publications (n = 30) mentioned downsides to rTKA. Overall, 89.3% of media articles presented a favorable view of rTKA. Ninety percent of RCTs reported that rTKA significantly outperformed manual TKA in terms of component positioning. Four of 6 RCTs reported significantly longer operative times with rTKA. Most RCTs found no significant differences in functional outcomes, opioid use, or complication rates.

CONCLUSIONS

The rate of publications on rTKA has increased substantially in media sources and peer-reviewed journals, with the volume of media articles far outpacing RCTs on the topic. More precise component positioning was the most consistently reported benefit of rTKA in RCTs. However, media sources also reported a range of other, less well-supported benefits, and employed overwhelmingly positive tones regarding rTKA, more so than is supported by mixed clinical results. Efforts to ensure that patients and health-care providers receive accurate and evidence-based information about new health technologies are critical.

CLINICAL RELEVANCE

This study demonstrates a clear disparity between news media coverage of rTKA and the best clinical evidence available. This information can help to guide discussions between patients and surgeons regarding the use of rTKA.

Accuracy of the Imageless Mode of the ROSA Robotic System for Targeted Resection Thickness in Total Knee Arthroplasty: A Prospective, Single Surgeon Case-Series Study

BACKGROUND

We investigated the accuracy of targeted resection thickness in patients undergoing primary Total Knee Arthroplasty (TKA) using the ROSA robotic system.

METHODS

Calliper measurements of the distal femur (DF), proximal tibia (PT), and posterior condyles (PC) were taken in 44 patients from June 2023 to January 2024.

RESULTS

Planned and actual resection depth difference was 0.67 mm ± 0.6 mm (mean ± SD) (p = 0.217) and 0.94 mm ± 1.15 mm (p = 0.4) for medial and lateral DF, 0.93 mm ± 0.81 mm (p = 0.001) and 0.89 mm ± 0.8 mm (p = 0.008) for medial and lateral PT, and 1.1 mm ± 0.97 mm (p = 0.001) and 1.04 mm ± 0.79 mm (p = 0.001) for medial and lateral PC, respectively.

CONCLUSION

The ROSA robotic system can achieve a high degree of accuracy for planned resection thickness. Results are valid only for the imageless ROSA TKA in patients with primary knee osteoarthritis.

The effect of different alignment strategies on trochlear orientation after total knee arthroplasty

PURPOSE

When planning and delivering total knee arthroplasty (TKA), there are multiple coronal alignment strategies such as functional alignment (FA), kinematic alignment (KA), mechanical and adjusted mechanical alignment (MA, aMA). Recent three-dimensional and robotic-assisted surgery (RAS) studies have demonstrated that KA potentially better restores the trochlear anatomy than MA. The purpose of this study was to compare the restoration of the native trochlear orientation in patients undergoing RAS TKA using four different alignment strategies. It was hypothesised that FA would result in the lowest number of outliers.

METHODS

This is a prospective study of 200 patients undergoing RAS-TKA with a single implant. All patients were analysed for MA and KA prebalancing, and 157 patients received aMA and 43 patients FA with intraoperative balancing. Preoperative transverse computed tomography scans were used to determine the posterior condylar axis (PCA), lateral trochlear inclination (LTI) angle, sulcus angle (SA) and anterior trochlear line (ATL) angle. Implant measurements were obtained using a photographic analysis. Intraoperative software data combined with implant data and preoperative measurements were used to calculate the differences. Outliers were defined as ≥3° of alteration. Trochlea dysplasia was defined as LTI < 12°.

RESULTS

Native transepicondylar PCA had a median of 2°, LTI 18°, SA 137°, ATL 4°. LTI outliers were observed in 47%-60% of cases, with KA < FA < aMA < MA. For ATL, the range of outliers was 40.5%-85%, KA < FA < aMA < MA. SA produced 81% of outliers. Of all median angle values, only LTI when using KA was not significantly altered compared to the native knee.

CONCLUSION

There is a significant alteration of trochlear orientation after TKA, regardless of the alignment strategy used. KA produced the lowest, but a substantial, number of outliers. The uniform design of implants causes the surgeon to compromise on balance in flexion versus trochlear position. The clinical relevance of this compromise requires further clinical investigations.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Robotic assisted Total Knee Arthroplasty (TKA) is not associated with increased patient satisfaction: a systematic review and meta-analysis

PURPOSE

Total knee arthroplasty (TKA) is a common orthopedic surgery, yet postoperative dissatisfaction persists in around 20% of cases. Robotic total knee arthroplasty (rTKA) promises enhanced precision, but its impact on patient satisfaction compared to conventional TKA remains controversial (cTKA). This systematic review aims to evaluate patient satisfaction post-rTKA and compare outcomes with cTKA.

METHODS

Papers from the following databases were identified and reviewed: PubMed, Scopus, Web of Science, and the Cochrane Online Library, using keywords like "Knee replacement," "Total knee arthroplasty," "Robotic," and "Patient satisfaction." Extracted data included patient satisfaction measures, Knee Society Score, Oxford Knee Score, Forgotten Joint Score, SF-36, HSS, and KOOS. Statistical analysis, including odds ratio and 95% CI was performed using R software. Heterogeneity was assessed using Cochrane's Q test.

RESULTS

The systematic review included 17 articles, involving 1148 patients (571 in the rTKA group and 577 in the cTKA group) assessing patient satisfaction following rTKA. An analysis of proportions reveals rTKA satisfaction rate was 95%, while for cTKA, it was 91%. A meta-analysis comparing rTKA and cTKA found no statistically significant difference in patient satisfaction. Additionally, various patient-reported outcome measures (PROMs) were examined, showing mixed results across different studies and follow-up periods.

CONCLUSIONS

The results of this study found no difference in patient satisfaction outcomes in the short to mid-term for rTKA compared to conventional methods. This study does not assert superiority for the robotic approach, highlighting the need for careful consideration of various factors influencing outcomes in knee arthroplasty.

Clinical, functional, and radiological outcomes of robotic assisted versus conventional total hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials

This systematic review of randomized controlled trials (RCTs) aims to compare important clinical, functional, and radiological outcomes between robotic-assisted total hip arthroplasty (RATHA) and conventional total hip arthroplasty (COTHA) in patients with hip osteoarthritis. We identified published RCTs comparing RATHA with COTHA in Ovid MEDLINE, EMBASE, Scopus, and Cochrane Library. Two reviewers independently performed study screening, risk of bias assessment and data extraction. Main outcomes were major complications, revision, patient-reported outcome measures (PROMs), and radiological outcomes. We included 8 RCTs involving 1014 patients and 977 hips. There was no difference in major complication rate (Relative Risk (RR) 0.78; 95% Confidence Interval (CI) 0.22 to 2.74), revision rate (RR 1.33; 95%CI 0.08 to 22.74), and PROMs (standardized mean difference 0.01; 95%CI - 0.27 to 0.30) between RATHA and COTHA. RATHA resulted in little to no effects on femoral stem alignment (mean difference (MD) - 0.57 degree; 95%CI - 1.16 to 0.03) but yielded overall lower leg length discrepancy (MD - 4.04 mm; 95%CI - 7.08 to - 1.0) compared to COTHA. Most combined estimates had low certainty of evidence mainly due to risk of bias, inconsistency, and imprecision. Based on the current evidence, there is no important difference in clinical and functional outcomes between RATHA and COTHA. The trivial higher radiological accuracy was also unlikely to be clinically meaningful. Regardless, more robust evidence is needed to improve the quality and strength of the current evidence.PROSPERO registration: the protocol was registered in the PROSPERO database (CRD42023453294). All methods were carried out in accordance with relevant guidelines and regulations.

Robotic Total Knee Arthroplasty: An Update

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

Comparison of imageless robotic assisted total knee arthroplasty and conventional total knee arthroplasty: early clinical and radiological outcomes of 200 knees

The aim of this study was to compare the short term clinical and radiological outcomes of imageless robotic and conventional total knee arthroplasty (TKA) and to estimate the accuracy of the two techniques by analysing the outliers after TKA. We have evaluated 200 consecutive knees (158 patients), 100 knees undergoing robotic TKA, and 100 knees treated with conventional TKA. Demographic parameters like age, gender, body mass index, diagnosis and range of motion were obtained. Knee society score (KSS) and Knee society functional score (KSS-F) were used for clinical evaluation. Mechanical alignment (Hip-knee-ankle angle), proximal tibial angle (MPTA), distal femoral angle (LDFA) and tibial slope were analysed for radiological results and outliers were compared between both groups. Outliers were defined when the measured angle exceeded ± 3° from the neutral alignment in each radiological measurement on the final follow-up radiograph.The minimum follow-up was 6 months (range, 6 to 18 months). The preoperative mean HKA angle was 169.7 ± 11.3° in robotic group and 169.3 ± 7.3° in conventional group. There was significant improvement in HKA, LDFA, MPTA and tibial slope compared to the preoperative values in both the groups (p < 0.01). The number of HKA, LDFA and tibial slope outliers were 31, 29 and 37, respectively, in the conventional group compared to 13, 23 and 17 in the robotic group (p < 0.01). There was a significant improvement in the KSS and KSS-F functional scores postoperatively in both the groups (p < 0.01). However, there was no significant difference in the functional scores between the groups postoperatively (p = 0.08). This study showed excellent improvement with both imageless robotic and conventional TKA, with similar clinical outcomes between both groups. However, radiologically robotic TKA showed better accuracy and consistency with fewer outliers compared with conventional TKA.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

Level of Evidence

Level III.

High three-dimensional accuracy of component placement and lower limb alignment using a robotic arm-assisted system and gap-balancing instrument in total knee arthroplasty

PURPOSE

It was hypothesized that robotic arm-assisted total knee arthroplasty (RA-TKA) using additionally a gap-balancing instrumentation will show high accuracy in executing the planning in femoral and tibial component placement throughout the range of knee motion (ROM) during TKA surgery.

METHODS

Prospectively collected data were analysed for patients undergoing RA-TKA. A cruciate retaining cemented design was implanted using the MAKO® robotic system. Lower limb alignment at 0°, 30°, 45°, 60° and 90° of flexion was recorded at the beginning of surgery and finally after implantation of the components. A ligament tensioner was inserted after tibial precut to measure the extension and flexion gap, and final component placement was planned based on 3D CT images. Femoral and tibial component placement was measured in all three planes.

RESULTS

A total of 104 patients were included (mean age 69.4 ± 9 years; 44 male, 60 female). The difference in component placement after planning and final implantation showed less valgus of 0.7° ± 1.4° (p < 0.001), less external rotation of 0.6° ± 1.9° (p = 0.001) and less flexion of 0.9° ± 1.8° (p < 0.001) for the femoral component. The tibial component was placed in more varus of 0.2° ± 0.9° (p = 0.056) and more posterior slope of 0.5° ± 0.9° (p < 0.001). The lower limb alignment in extension was 4.4° ± 5.2° of varus of the native knee and changed to 1.2° ± 1.9° of varus after TKA (p < 0.01).

CONCLUSION

Robotic-assisted TKA helps to achieve the target of alignment and component placement very close to the planning. It allows optimal component placement of off-the-shelf implants respecting patient's specific anatomy.

LEVEL OF EVIDENCE

Level II.

Technology assistance in primary total knee replacement: hype or hope?

INTRODUCTION

Total knee replacement (TKR) reduces pain, it increases quality of life and it generally lasts a long time with revision rates of less than 5% at 10 years. Some authors have suggested that outcomes may be further improved by technology assistance.

AREAS COVERED

Technology assistance in primary TKR includes technologies such as navigated TKR, patient specific instrumentation TKR and robotic TKR.

EXPERT OPINION

In general, technology assistance results in higher accuracy of component positioning and alignment, but this is likely not clinically relevant as no clinically important difference in clinical outcomes, quality of life and complications such as revisions has been demonstrated in meta-analyses of randomized controlled trials. As technology assistance in primary TKR is increasingly used to capture patient and surgeon data, surgeons have an increasingly important role in protecting their patients' data and their own data. Real world evidence of implant registries has shown that TKR without technologically assistance can achieve perfectly acceptable outcomes. Although there is a genuine hope that technology-assisted TKR may further improve these outcomes, this hope is based on promises rather than solid evidence. At the same time, technology assisted TKR is heavily promoted including direct patient marketing, which are aspects of a hype.

Robotic-assisted total knee arthroplasty results in decreased incidence of anterior femoral notching compared to posterior referenced instrumented total knee arthroplasty

OBJECTIVE

Periprosthetic fracture (PPF) is an uncommon but devastating complication after total knee arthroplasty (TKA). Anterior femoral notching (AFN) is one of a perioperative risk factor for PPF. The main purpose of this study was to compare between the rates of anterior femoral notching (AFN) and supracondylar periprosthetic femoral fracture (sPPF) of manual TKA and robotic arm-assisted TKA (RATKA). Meanwhile, blood loss, transfusion rates, inflammatory responses, complications, early clinical and radiological outcomes were also assessed.

METHODS

This retrospective study included 330 patients (133 RATKA and 197 manual TKA). Differences in risks of inflammatory, blood loss, complications (periprosthetic fracture and periprosthetic joint infection), pre-operative and post-operative distal lateral femoral angle (LDFA), distal femoral width (DFW), prosthesis-distal femoral width (PDFW) ratio, AFN, femoral component flexion angle (FCFA), peri-operative and post-operative functional outcomes between the RATKA and manual TKA groups were compared.

RESULTS

The operation time and postoperative CRP level in the RATKA group was significantly longer and higher than that in the manual TKA group (p < .001). However, there was no significant difference in postoperative WBC level (p = .217), hemoglobin loss (p = .362), postoperative drainage (p = .836), and periprosthetic fracture (p = 1.000). There was no significant difference in LDFA (p > .05), DFW(p = .834), PDFW ratio (p = .089) and FCFA (p = .315) between the two groups, but the rate of AFN in the RATKA group was significantly lower than that in the manual TKA group (p < .05). There was no significant difference in ROM between the two groups on POD3, POD 90 and 1 year (p < .05), but the FJS-12 score in the RATKA group was higher than that in the manual TKA group on 1 year (p = .001).

CONCLUSION

Robotic-assisted total knee arthroplasty can decrease the incidence of anterior femoral notching compared to posterior referenced instrumented total knee arthroplasty.

Functional positioning principles for image-based robotic-assisted TKA achieved a higher Forgotten Joint Score at 1 year compared to conventional TKA with restricted kinematic alignment

PURPOSE

Few comparative studies assessed the current concept of individualised alignment for total knee arthroplasty (TKA) and their outcomes at mid-term. This study aimed to evaluate the functional outcomes at 1 year of primary TKA performed with a functional positioning technique based on an image-based robotic-assisted system, compared to conventional TKA performed with a restricted kinematic alignment technique.

METHODS

This retrospective comparative study included 100 primary TKAs performed with functional positioning principles using an image-based robotic-assisted system. A control group included 100 primary TKAs with the same posterior-stabilised implant as the robotic group but performed with manual instrumentation and restricted kinematic alignment technique. In the robotic group, the mean age was 69.2 years old ± 7.9; the mean body mass index was 29.7 kg/m2 ± 4.6. The demographic characteristics were similar between both groups. Kujala score, Forgotten Joint Score (FJS), Knee Society Score (KSS) knee and KSS function were collected 12 months postoperatively. Normally distributed continuous variables were compared using the Student t test. For non-normally distributed continuous variables, the Mann-Whitney test was used.

RESULTS

FJS was significantly higher in the robotic group (76.3 ± 13 vs. 68.6 ± 16.9 in the conventional group; p = 0.026). At a 1-year follow-up, there was no significant difference in the KSS knee and KSS function scores and the Kujala score between both groups. The mean KSS knee score was 90.8 ± 11.4 in the robotic group versus 89.4 ± 9.6 in the conventional group (p = 0.082). The mean KSS function score was 91.4 ± 12.3 versus 91.3 ± 12.6, respectively (p = 0.778).

CONCLUSION

Functional positioning principles using an image-based robotic-assisted system achieved a higher Forgotten Joint Score 1 year after TKA compared to restricted kinematic alignment. Personalised alignment and implant positioning are interesting paths to improve the functional outcomes after TKA.

LEVEL OF EVIDENCE

III.

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

In total knee arthroplasty (TKA), functional knee phenotypes are of interest regarding surgical alignment strategies. Functional knee phenotypes were introduced in 2019 and consist of limb, femoral, and tibial phenotypes. The hypothesis of this study was that mechanically aligned (MA) TKA changes preoperative functional phenotypes, which decreases the 1-year Forgotten Joint (FJS) and Oxford Knee Score (OKS) and increases the 1-year WOMAC. All patients included in this study had end-stage osteoarthritis and were treated with a primary MA TKA, which was supervised by four academic knee arthroplasty specialists. To determine the limb, femoral, and tibial phenotype, a long-leg radiograph (LLR) was imaged preoperatively and two to three days after TKA. FJS, OKS, and WOMAC were obtained 1 year after TKA. Patients were categorized using the change in functional limb, femoral, and tibial phenotype measured on LLR, and the scores were compared between the different categories. A complete dataset of preoperative and postoperative scores and radiographic images could be obtained for 59 patients. 42% of these patients had a change of limb phenotype, 41% a change of femoral phenotype, and 24% a change of tibial phenotype of more than ±1 relative to the preoperative phenotype. Patients with more than ±1 change of limb phenotype had significantly lower median FJS (27 points) and OKS (31 points) and higher WOMAC scores (30 points) relative to the 59-, 41-, and 4-point scores of those with a 0 ± 1 change (p < 0.0001 to 0.0048). Patients with a more than ±1 change of femoral phenotype had significantly lower median FJS (28 points) and OKS (32 points) and higher WOMAC scores (24 points) relative to the 69-, 40-, and 8-point scores of those with a 0 ± 1 change (p < 0.0001). A change in tibial phenotype had no effect on the FJS, OKS, and WOMAC scores. Surgeons performing MA TKA could consider limiting coronal alignment corrections of the limb and femoral joint line to within one phenotype to reduce the risk of low patient-reported satisfaction and function at 1-year.