Minimally Invasive Computer-Assisted Total Knee Arthroplasty Compared With Conventional Total Knee Arthroplasty: A Prospective 9-Year Follow-Up

The Reverse Fragility Index: Interpreting the Current Literature on Long-Term Survivorship of Computer-Navigated Versus Conventional TKA: A Systematic Review and Cross-Sectional Study of Randomized Controlled Trials

BACKGROUND

Despite the most recent American Academy of Orthopaedic Surgeons clinical practice guideline making a "strong" recommendation against the use of intraoperative navigation in total knee arthroplasty (TKA), its use is increasing. We utilized the concept of the reverse fragility index (RFI) to assess the strength of neutrality of the randomized controlled trials (RCTs) comparing the long-term survivorship of computer-navigated and conventional TKA.

METHODS

A systematic review was performed including all RCTs through August 3, 2021, comparing the long-term outcomes of computer-navigated and conventional TKA. Randomized trials with mean follow-up of >8 years and survivorship with revision as the end point were included. The RFI quantifies the strength of a study's neutrality by calculating the minimum number of events necessary to flip the result from nonsignificant to significant. The RFI at a threshold of p < 0.05 was calculated for each study reporting nonsignificant results. The reverse fragility quotient (RFQ) was calculated by dividing the RFI by the study sample size.

RESULTS

Ten clinical trials with 2,518 patients and 38 all-cause revisions were analyzed. All 10 studies reported nonsignificant results. The median RFI at the p < 0.05 threshold was 4, meaning that a median of 4 events would be needed to change the results from nonsignificant to significant. The median RFQ was 0.029, indicating that the nonsignificance of the results was contingent on only 2.9 events per 100 participants. The median loss to follow-up was 27 patients. In all studies, the number of patients lost to follow-up was greater than the RFI.

CONCLUSIONS

The equipoise in long-term survivorship between computer-navigated and conventional TKA rests on fragile studies, as their statistical nonsignificance could be reversed by changing the outcome status of only a handful of patients--a number that was always smaller than the number lost to follow-up. Routine reporting of the RFI in trials with nonsignificant findings may provide readers with a measure of confidence in the neutrality of the results.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Can Technology Assistance be Cost Effective in TKA? A Simulation-Based Analysis of a Risk-prioritized, Practice-specific Framework

BACKGROUND

Robotic, navigated, and patient-specific instrumentation (PSI) TKA procedures have been introduced to improve component placement precision and improve implant survivorship and other clinical outcomes. However, the best available evidence has shown that these technologies are ineffective in reducing revision rates in the general TKA patient population. Nonetheless, it seems plausible that these technologies could be an effective and cost-effective means of reducing revision risk in clinical populations that are at an elevated risk of revision because of patient-specific demographics (such as older age at index surgery, elevated BMI, and being a man). Since clinical trials on this topic would need to be very large, a simulation approach could provide insight on which clinical populations would be the most promising for analysis.

QUESTIONS/PURPOSES

We conducted a simulation-based analysis and asked: (1) Given key demographic parameters characterizing a patient population, together with estimates of the precision achievable with selected forms of technology assistance in TKA, can we estimate the expected distributions of anticipated reductions in lifetime revision risk for that population and the associated improvements in quality-adjusted life years (QALYs) that would be expected to result? (2) Are there realistic practice characteristics (such as combinations of local patient demographics and capital and per-procedure costs) for which applying a per-patient risk-prioritized policy for using technology-assisted TKA could be considered cost-effective based on projected cost savings from reductions in revision rates?

METHODS

We designed simulations of hypothetical practice-specific clinical scenarios, each characterized by patient volume, patient demographics, and technology-assisted surgical technique, using demographic information drawn from other studies to characterize two contrasting simulated clinical scenarios in which the distributions of factors describing patients undergoing TKA place one population at a comparatively elevated risk of revision (elevated-risk population) and the second at a comparatively reduced risk of revision (lower-risk population). We used results from previous systematic reviews and meta-analyses to estimate the implant precision in coronal plane alignment for patient-specific instrumentation, navigated, and robotic technology. We generated simulated TKA patient populations based on risk estimates from large clinical studies, structured reviews, and meta-analyses and calculated the patient-specific reduction in the revision risk and the change in QALYs attributable to the technology-assisted intervention in each of the two simulated clinical scenarios. We also incorporated a sensitivity analysis, incorporating variations in the effect size of deviations from overall coronal alignment on revision risk and difference in health state utilities acquired through a structured review process. We then simulated the outcomes of 25,000 operations per patient using the precisions associated with the conventional TKA technique, the three technology-assisted techniques, and a hypothetical technology-assisted intervention that could consistently deliver perfectly neutral overall coronal alignment, which is unachievable in practice. A risk-prioritized treatment policy was emulated by ordering the simulated patients from the highest to lowest predicted increase in QALYs, such that simulated patients who would see the greatest increase in the QALYs (and therefore the greatest reduction in lifetime revision risk) were the patients to receive technology-assisted TKA intervention in a practice. We used cost estimates acquired through a structured review process and calculated the net added costs of each of the three technology-assisted techniques as a function of the percent utilization (proportion of patients treated with technology assistance in a practice), factoring in fixed costs, per-procedure variable costs, and savings occurring from the prevention of future revision surgery. Finally, we calculated the incremental cost-effectiveness ratio (ICER) and marginal cost-effectiveness ratio (MCER) for each technology-assisted technique for the two clinical scenarios. We then used a Monte Carlo approach to simulate variations in key patient risk, health state, and economic factors as well as to obtain a distribution of estimates for cost-effectiveness. We considered an intervention to be cost effective if either the ICER or MCER values were below USD/QALY 63,000.

RESULTS

For the lower-risk population, the median reduction in the revision risk was 0.9% (0.4% to 2.2%, extrema from the sensitivity analysis) and 1.8% (0.9% to 4.4%) for PSI and robotic TKA, respectively, and 1.9% (1.0% to 4.6%) for ideal TKA. In contrast, the median reduction in the revision risk in the elevated-risk clinical scenario was 2.0% (1.2% to 3.4%) and 4.6% (2.7% to 8.5%) for PSI and robotic TKA and 5.1% (3.0% to 9.4%) for ideal TKA. Estimated differences in the cumulative gain in QALYs attributable to technology-assisted TKA ranged from 0.6 (0.2 to 1.8) to 4.0 (1.8 to 10.0) QALYs per 100 patients, depending on the intervention type and clinical scenario. For PSI, we found treating 15% of patients in the lower-risk population and 77% in the elevated-risk population could meet the threshold for being considered cost effective. For navigated TKA systems offering high alignment precision, we found the intervention could meet this threshold for practice sizes of at least 300 patients per year and a percent utilization of 27% in the lower-risk population. In the elevated-risk population, cost-effectiveness could be achieved in practice volumes as small as 100 patients per year with a percent utilization of at least 6%, and cost savings could be achieved with a percent utilization of at least 45%. We found that robotic TKA could only meet the threshold for being considered cost-effectiveness in the lower-risk population if yearly patient volumes exceeded 600 and for a limited range of percent utilization (27% to 32%). However, in the elevated-risk patient population, robotic TKA with high alignment precision could potentially be cost effective for practice sizes as small as 100 patients per year and a percent utilization of at least 20% if a risk-prioritized treatment protocol were used.

CONCLUSION

Based on these simulations, a selective-use policy for technology-assisted TKA that prioritizes using technology assistance for those patients at a higher risk of revision based on patient-specific factors could potentially meet the cost-effectiveness threshold in selected circumstances (for example, primarily in elevated-risk populations and larger practice sizes). Whether it does meet that threshold would depend significantly on the surgical precision that can be achieved in practice for a given proposed technology as well as on the true local costs of using the proposed technology. We further recommend that any future randomized trials seeking to demonstrate possible effects of technology assistance on revision risk focus on clinical populations that are at higher risk of revision (such as, patient populations that are relatively younger, have higher BMIs, and higher proportions of men).

CLINICAL RELEVANCE

This study suggests that technology assistance is only likely to prove cost effective in selected circumstances rather than in all clinical populations and practice settings. In general, we project that surgical navigation is most likely to prove cost effective in the widest range of circumstances, that PSI may be cost effective or cost neutral in a moderate range of circumstances, and that robotic surgery is only likely to be cost effective in moderately large practices containing patients who are on average at an intrinsically elevated risk of revision.

Comparison of Survival Rate and Outcomes Between Conventional and Navigation-Assisted Primary Total Knee Arthroplasty in Severe Varus Knees: A Minimum 10-Year Follow-Up

BACKGROUND

This study aimed to compare the long-term clinical and radiographic outcomes and survival rates between navigation-assisted (NAV) total knee arthroplasty (TKA) and conventional (CON) TKA in patients with preoperative severe varus deformity.

METHODS

From January 2005 to December 2011, 152 TKAs and 62 TKAs with preoperative hip-knee-ankle (HKA) angles more than 15° were enrolled in the CON-TKA and NAV-TKA group with 135.7 months follow-up. Clinical outcomes (Western Ontario and McMaster University Osteoarthritis Index and Knee Society Scores), radiographic outcomes (HKA, α, β, γ, and δ angles), and survivorship were compared between the groups.

RESULTS

The mean value of radiographic outcomes was not statistically different; however, outliers of the HKA angle were significantly higher in the CON-TKA group (18.4% versus 8.1%, P = .04). However, long-term clinical outcomes were similar between both groups. The cumulative survival rate was 96.1% in the CON-TKA group and 96.8% in the NAV-TKA group, with no difference between the groups (P = .962).

CONCLUSION

NAV-TKA showed fewer outliers in the HKA angle for severe preoperative varus deformity compared with CON-TKA. The long-term clinical outcomes and survival rates were similar between the 2 techniques. A survival rate of more than 96% was observed in both groups.

STUDY DESIGN

Level III, retrospective comparative study.

Early Superior Clinical Outcomes in Robotic-Assisted TKA Compared to Conventional TKA in the Same Patient: A Comparative Analysis

Robotic-assisted total knee arthroplasty (RA-TKA) has demonstrated improved alignment and outcome scores when compared with manual total knee arthroplasty (M-TKA); however, few studies compare differences in the same patient. This study is a retrospective review that assesses clinical outcomes of 36 patients who underwent a primary RA-TKA and had undergone a prior contralateral M-TKA. All surgeries were performed by a single surgeon at the same institution. Patients were assessed for differences in hospital length of stay, improvement in pre- versus postoperative range of motion, Knee Injury and Osteoarthritis Outcome Score (KOOS), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores. Student's t-test and Fisher's exact test were utilized to detect significant differences. Patient demographics showed a mean age of 64.5, 24 females (67%), and mean body mass index of 35.1 ± 5.7. The average follow-up time was 2.9 years for M-TKA and 1.3 years for RA-TKA. Hospital length of stay was decreased by 5.5 hours for RA-TKA (p = 0.03). Total postoperative WOMAC score was not statistically different between RA-TKA and M-TKA (p = 0.061); however, pain and stiffness components were statistically improved in RA-TKA (p = 0.041 and p = 0.007), respectively. KOOS was higher in RA-TKA, which approached statistical significance (p = 0.005). Pre- versus postoperative knee flexion improved significantly in both cohorts. There was a significant difference in pre- versus postoperative range of motion at 3, 6, and 12 months follow-up after RA-TKA in comparison to M-TKA (p < 0.05). There were no postoperative complications. Patients who underwent RA-TKA demonstrated early improvement at 1-year follow-up in pain, stiffness, and knee flexion when compared with their prior contralateral M-TKA. There was a significant decrease in postoperative length of stay by 5.5 hours in the RA-TKA group. Limitations include a small sample size and differences in follow-up times between RA-TKA and M-TKA.

How Large a Study Is Needed to Detect TKA Revision Rate Reductions Attributable to Robotic or Navigated Technologies? A Simulation-based Power Analysis

BACKGROUND

Robotic and navigated TKA procedures have been introduced to improve component placement precision in the hope of improving implant survivorship and other clinical outcomes. Although numerous comparative studies have shown enhanced precision and accuracy in placing components, most comparative studies have not shown that such interventions result in improved implant survival. Given what we know about effect sizes from large arthroplasty registries, large cohort studies, and large randomized controlled trials (RCTs), we wondered how large randomized trials would need to be to detect such small differences, and if the number is very high, what that would tell us about the value of these treatments for preventing revision surgery.

QUESTIONS/PURPOSES

In this simulation study, we asked: Given that survivorship differences between technology-assisted TKA (TA-TKA, which we defined as either navigated or robot-assisted TKA) and conventional TKA are either small or absent based on large arthroplasty registries, large cohort studies, and large RCTs, how large would randomized trials need to be to detect small differences between TA-TKA and conventional TKA if they exist, and how long would the follow-up period need to be to have a reasonable chance to detect those differences?

METHODS

We used estimated effect sizes drawn from previous clinical and registry studies, combined with estimates of the accuracy and precision of various navigation and robotic systems, to model and simulate the likely outcomes of potential comparative clinical study designs. To characterize the ranges of patients enrolled and general follow-up times associated with traditional RCT studies, we conducted a structured search of previously published studies evaluating the effect of robotics and navigation on revision rates compared with that of conventional TKA. The structured search of the University of British Columbia's library database (which automatically searches medical publication databases such as PubMed, Embase, Medline, and Web of Science) and subsequent searching through included studies' reference lists yielded 103 search results. Only clinical studies assessing implant survival differences between patient cohorts of TA-TKA and conventional TKA were included. Studies analyzing registry data, using cadaver specimens, assessing revision TKA, conference proceedings, and preprint services were excluded. Twenty studies met all our inclusion criteria, but only one study reported a statistically significant difference between the conventional and robotic or navigated groups. Next, we generated a large set of patients with simulated TKA (1.5 million), randomly assigning each simulated patient a set of patient-specific factors (age at the index surgery, gender, and BMI) drawn from data from registries and published information. We divided this set of simulated procedures into four groups, each associated with a coronal alignment precision reported for different types of surgical procedures, and randomly assigned each patient an overall coronal alignment consistent with their group's precision. TA procedures were modeled based on the alignment precision that an intervention could deliver, regardless of whether the technology used was navigation- or robot-assisted. To evaluate the power associated with using different cohort sizes, we ran a Monte Carlo simulation generating 3000 simulated populations that were drawn (with replacement) from the large set of simulated patients with TKA. We simulated the time to revision for aseptic loosening for each patient, computed the corresponding Kaplan-Meier survival curves, and applied a log-rank test to each study for statistical differences in revision rates at concurrent follow-up timepoints (1-25 years). From each simulation associated with a given cohort size, we determined the percentage of simulated studies that found a statistically significant difference at each follow-up interval. For each alternative precision, we then also calculated the expected reduction in revision rates (effect size) attributable to TA-TKA intervention and the number needed to treat (NNT) using TA-TKA to prevent one revision at 2, 5, 10, and 15 years after index surgery for the entire set of Kaplan-Meier survival analyses.

RESULTS

The results from our simulation found survivorship differences favoring TA-TKA ranging from 1.4% to 2.0% at 15 years of follow-up. Comparative studies would need to enroll between 2500 and 4000 patients in each arm of the study, depending on the precision of the navigated or robotic procedure, to have an 80% chance of showing this reduction in revision rates at 15 years of follow-up. For the highest precision simulated intervention, the NNT using TA-TKA to prevent one revision was 1000 at 2 years, 334 at 5 years, 100 at 10 years, and 50 at 15 years post-index surgery.

CONCLUSION

Based on these simulations, it appears that TA-TKA interventions could potentially result in a relative reduction in revision rates as large as 27% (from 7.5% down to about 5.5% at 15 years for the intervention with the most precise coronal alignment); however, since this 2% absolute reduction in revision rates is relatively small in comparison with the baseline success rate of TKA and would not be realized until 15 years after the index surgery, traditional RCT studies would require excessively large numbers of patients to be enrolled and excessively long follow-up times to demonstrate whether such a reduction actually exists.

CLINICAL RELEVANCE

Given that the NNTs to avoid revisions at various time points are predicted to be high, it would require correspondingly low system costs to justify broad adoption of TA-TKA based on avoided revision costs alone, though we speculate that technology assistance could perhaps prove to be cost effective in the care of patients who are at an elevated risk of revision.

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.

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.

Better outcomes after minimally invasive surgeries compared to the standard invasive medial parapatellar approach for total knee arthroplasty: a meta-analysis

PURPOSE

Minimally invasive surgery (MIS) for total knee arthroplasty (TKA) is often marketed as being able to speed up healing times over standard invasive surgery (SIS) through the medial parapatellar approach. The advantages of these minimally invasive approaches, however, are not yet definitively established. A meta-analysis of studies comparing peri-operative and post-operative differences and long-term complications of MIS versus SIS for TKA was conducted.

METHODS

This meta-analysis was conducted following the PRISMA guidelines. The Pubmed, Google Scholar, Scopus, and Embase databases were accessed in September 2020. All clinical trials comparing minimally-invasive versus standard approaches for TKA were considered. Only studies reporting quantitative data under the outcomes of interest were included. Methodological quality assessment was performed using the PEDro appraisal score.

RESULTS

This meta-analysis covers a total of 38 studies (3296 procedures), with a mean 21.3 ± 24.3 months of follow-up. The MIS group had shorter hospitalization times, lower values of total estimated blood loss, quicker times of straight-leg raise, greater values for range of motion, higher scores on the Knee Society Clinical Rating System (KSS) and its related Function Subscale (KSFS). Pain scores, anterior knee pain and revision rate were similar between MIS and SIS. SIS allowed a quicker surgical duration.

CONCLUSION

The present meta-analysis encourages the use of minimally invasive techniques for total knee arthroplasty. However, MIS TKA is technically demanding and requires a long learning curve.

LEVEL OF EVIDENCE

III, meta-analysis of clinical trials.

Comparison of the clinical effects of computer-assisted and traditional techniques in bilateral total knee arthroplasty: A meta-analysis of randomized controlled trials

Background

It is unclear whether there are individual differences in the long-term efficacy of computer-assisted and traditional total knee arthroplasty. The purpose of this study was to perform a meta-analysis comparing the same individuals undergoing computer-assisted and traditional total knee arthroplasty separately to determine whether computer-assisted total knee arthroplasty can provide better lower extremity radiographic results and clinical outcomes.

Methods

We searched literatures to identify relevant randomized controlled trials comparing the effects of computer-assisted and traditional methods in bilateral total knee arthroplasty. After screening, quality evaluation and data extraction according to inclusion and exclusion criteria, the quality and bias risks of the included studies were evaluated. The meta-analysis compared the radiographic results, functional outcomes and complications of the two techniques.

Results

Six clinical controlled trials were included, with total of 1098 patients. The meta-analysis showed that the accuracy in terms of the mechanical axis of the lower extremity, the sagittal alignment of the femoral component and the coronal alignment of the tibial component in computer-assisted total knee arthroplasty was significantly better than those in traditional total knee arthroplasty. There were no differences in the functional results, revision rates or aseptic loosening rates between the two techniques.

Conclusion

After excluding individual differences such as bone development and bone quality, although computer-assisted techniques can better accurately correct the mechanical axis of the lower extremity and the position of prosthesis implantation than traditional techniques, there is no significant difference in the functional results and revision rate of bilateral total knee arthroplasty in the same individual.

Better outcomes after mini-subvastus approach for primary total knee arthroplasty: a Bayesian network meta-analysis

Introduction

Alternatives to the classical medial parapatellar (MPP) approach for total knee arthroplasty (TKA) include the mini-medial parapatellar (MMPP), mini-subvastus (MSV), mini-midvastus (MMV) and quadriceps-sparing (QS) approaches. The best approach has been not fully clarified. The purpose of the present study was to conduct a Bayesian network meta-analysis comparing these approaches.

Materials and methods

The present analysis was carried out according to the PRISMA extension statement for reporting systematic reviews incorporating network meta-analyses of healthcare interventions. The databases search was performed in October 2019. All clinical trials comparing two or more approaches for primary TKA were considered for inclusion. The baseline comparability was evaluated through the analysis of variance (ANOVA) test. The statistical analysis was performed through the STATA software/MP. A Bayesian hierarchical random-effects model analysis was adopted in all the comparisons.

Results

Data from 52 articles (4533 patients) were collected. The mean follow-up was 20.38 months. With regard to diagnosis, gender, age and BMI, adequate baseline comparability was detected. The MSV approach ranked better concerning clinical scores (the lowest visual analogic scale, the higher KSS and KSFS) and functional outcomes (the shortest straight leg raise, the greatest degree of flexion and range of motion). Concerning perioperative data, the MSV evidenced the shortest hospital stay, while the MPP the shortest surgical duration and lowest estimated blood loss.

Conclusion

According to the main findings of the present study, the mini-subvastus approach for total knee arthroplasty demonstrated superior overall compared to the other approaches. Orthopaedic surgeons should consider this approach in the light of the evidence and limitations of this Bayesian network meta-analysis.

A Comparison of Long-Term Outcomes of Computer-Navigated and Conventional Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

It is not clear whether long-term outcomes differ between computer-navigated and conventional total knee arthroplasty. The purpose of this study was to perform a meta-analysis comparing the radiographic outcomes, the long-term functional outcomes, and survivorship between computer-navigated total knee arthroplasty and conventional total knee arthroplasty.

METHODS

We searched MEDLINE, Embase, and the Cochrane Library to identify studies comparing long-term outcomes between computer-navigated total knee arthroplasty and conventional total knee arthroplasty. Randomized controlled trials with mean follow-up durations of >8 years were included. The meta-analysis compared radiographic outcomes (postoperative alignment), functional outcomes (range of motion and patient-reported outcomes), and survivorship of the 2 techniques.

RESULTS

Nine studies were included. A meta-analysis of accuracy revealed better outcomes in computer-navigated total knee arthroplasty when compared with conventional total knee arthroplasty in terms of the sagittal alignment of the femoral component (risk ratio [RR], 0.69; [95% confidence interval (CI), 0.51 to 0.93]; p = 0.02) and the coronal alignment of the tibial component (RR, 0.75 [95% CI, 0.60 to 0.95]; p = 0.02). The mechanical axis of the lower extremity, the coronal alignment of the femoral component, and the sagittal alignment of the tibial component did not differ significantly between the 2 groups. The functional outcomes did not differ significantly between the 2 techniques. Both in terms of the revision rate and the incidence of aseptic loosening, there were no differences between the 2 techniques.

CONCLUSIONS

Although computer-navigated total knee arthroplasty resulted in better outcomes in postoperative component alignment than conventional total knee arthroplasty, there were no significant differences in long-term functional outcomes and survivorship between the 2 techniques. To fully evaluate the utility of computer navigation in total knee arthroplasty, additional randomized controlled studies including diverse ethnic groups and countries, as well as studies evaluating the correlation between postoperative alignment and long-term survivorship, are necessary.

LEVEL OF EVIDENCE

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

Single intra-articular injection of fluvastatin-PLGA microspheres reduces cartilage degradation in rabbits with experimental osteoarthritis

Statins are cholesterol-lowering drugs that inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, a rate-limiting enzyme of the mevalonate pathway. The anti-inflammatory effect of statins has been reported in recent years. The present study investigated therapeutic effects of the local administration of statin in osteoarthritis (OA). We assessed clinically used statins and selected fluvastatin for further experimentation, as it showed potent anabolic and anti-catabolic effects on human OA chondrocytes. To achieve controlled intra-articular administration of statin, we developed an intra-articular injectable statin using poly(lactic-co-glycolic acid) (PLGA) as a drug delivery system (DDS). The release profile of the statin was evaluated in vitro. Finally, therapeutic effects of fluvastatin-loaded PLGA microspheres (FLU-PLGA) were tested in a rabbit OA model. Rabbit knees were divided into four subgroups: group 1-A, PLGA-treated group; group 1-B, PLGA contralateral saline control group; group 2-A, FLU-PLGA-treated group; and group 2-B, FLU-PLGA contralateral saline control group. Histological analysis 5 weeks after intra-articular injection revealed that OARSI scores were lower in group 2-A. No significant differences in OARSI scores were observed between groups 1-A, 1-B, and 2-B. This study indicates that a single intra-articular injection of fluvastatin-loaded PLGA microspheres could be a novel therapeutic approach for treating patients with OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2465-2475, 2017.

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

Recently, there is a growing interest in surgical variables that are intraoperatively controlled by orthopaedic surgeons, including lower leg alignment, component positioning and soft tissues balancing. Since more tight control over these factors is associated with improved outcomes of unicompartmental knee arthroplasty and total knee arthroplasty (TKA), several computer navigation and robotic-assisted systems have been developed. Although mechanical axis accuracy and component positioning have been shown to improve with computer navigation, no superiority in functional outcomes has yet been shown. This could be explained by the fact that many differences exist between the number and type of surgical variables these systems control. Most systems control lower leg alignment and component positioning, while some in addition control soft tissue balancing. Finally, robotic-assisted systems have the additional advantage of improving surgical precision. A systematic search in PubMed, Embase and Cochrane Library resulted in 40 comparative studies and three registries on computer navigation reporting outcomes of 474,197 patients, and 21 basic science and clinical studies on robotic-assisted knee arthroplasty. Twenty-eight of these comparative computer navigation studies reported Knee Society Total scores in 3504 patients. Stratifying by type of surgical variables, no significant differences were noted in outcomes between surgery with computer-navigated TKA controlling for alignment and component positioning versus conventional TKA (p = 0.63). However, significantly better outcomes were noted following computer-navigated TKA that also controlled for soft tissue balancing versus conventional TKA (mean difference 4.84, 95 % Confidence Interval 1.61, 8.07, p = 0.003). A literature review of robotic systems showed that these systems can, similarly to computer navigation, reliably improve lower leg alignment, component positioning and soft tissues balancing. Furthermore, two studies comparing robotic-assisted with computer-navigated surgery reported superiority of robotic-assisted surgery in controlling these factors. Manually controlling all these surgical variables can be difficult for the orthopaedic surgeon. Findings in this study suggest that computer navigation or robotic assistance may help managing these multiple variables and could improve outcomes. Future studies assessing the role of soft tissue balancing in knee arthroplasty and long-term follow-up studies assessing the role of computer-navigated and robotic-assisted knee arthroplasty are needed.

Does computer-assisted surgery influence survivorship of cementless total knee arthroplasty in patients with primary osteoarthritis? A 10-year follow-up study

PURPOSE

Computer-assisted surgery (CAS) has been proposed to improve the performance of total knee arthroplasty (TKA) by reducing implant mal-position and mechanical axis mal-alignment. However, no clinical study has been performed to evaluate whether CAS improves survivorship of cementless TKA at long-term follow-up. This prospective and comparative study evaluated the outcome and survivorship of a cementless rotating mobile-bearing TKA performed with or without CAS at a minimum 10-year follow-up.

METHODS

A continuous series of 138 TKA (SCORE^®, Amplitude, Valence, France) comparing 87 CAS TKA versus 51 conventional mechanical technique (MECA) TKA was prospectively included in our total joint registry.

RESULTS

At 10.5 years after implantation, 95 TKA (59 CAS and 36 MECA TKA) were evaluated. No significant difference was detected in the clinical outcome and mechanical axis between the two groups. The overall 10-year survivorship using revision for any reason as end-point was 91 ± 5 % without significant difference detected between the two groups [86 ± 10 % in the MECA group and 94 ± 5 % in the CAS group (n.s.)]. Using aseptic loosening as end-point, the 10-year survivorship was 100 % in both groups. Using secondary patellar resurfacing as end-point, the 10-year survivorship was significantly higher in the CAS than in MECA group (100 and 85 ± 15 %, respectively; p = 0.0039).

CONCLUSION

With no implant aseptic loosening or mechanical failure at 10.5 years after implantation, the cementless rotating mobile-bearing SCORE^® TKA demonstrated favourable survivorship without influence of CAS. However, CAS might influence TKA survivorship by limiting secondary patellar resurfacing.

LEVEL OF EVIDENCE

Therapeutic, Level II.

Computer-assisted stereotaxic navigation improves the accuracy of mechanical alignment and component positioning in total knee arthroplasty

INTRODUCTION

This study reports on a novel computer-assisted stereotaxic navigation (CASN) system that attempts to combine the accuracy of computer navigation with familiarity of conventional methods. We hypothesize that CASN would improve mechanical alignment and component positioning when compared to conventional instrumentation.

MATERIALS AND METHODS

145 patients (192 knees) retrospectively matched for age, BMI, gender and pre-operative scores, underwent total knee arthroplasty (TKA) using CASN (n = 92) or conventional instrumentation (n = 100). Pre- and post-operative radiological alignment [Acceptable ranges: mechanical axis (MA) 0° ± 3°, coronal femoral-component angle (CFA) and coronal tibia-component angle (CTA) 90° ± 3°] and clinical outcomes (Knee Society Scores, Oxford Knee Score and Short Form-36) at 6 months were examined.

RESULTS

The CASN group had significantly improved mean MA (1.9° ± 1.4°, versus 2.8° ± 2.0° in the conventional group, p = 0.001), CFA (1.6° ± 1.3°, versus 2.1° ± 1.5° in the conventional group, p = 0.035) and CTA (1.6° ± 1.2°, versus 2.1° ± 1.5° in the conventional group, p = 0.024). 91.3 % of knees in the CASN group were within 3° of a neutral mechanical axis, versus 74 % in the conventional group (p < 0.001). The duration of surgery was significantly longer in the CASN group (84 ± 22 vs 73 ± 15 min, p = 0.001) and cost an additional USD 850 per operation. There were no significant differences in clinical outcomes or satisfaction rates at 6 months post-operatively (p > 0.05).

CONCLUSIONS

CASN improved TKA mechanical alignment and component positioning, however, resulted in longer and costlier surgery with no benefits in short-term functional outcomes, despite providing familiarity to surgeons accustomed to conventional instrumentation.

LEVEL OF EVIDENCE

III.