Navigation in minimally invasive unicompartmental knee arthroplasty has no advantage in comparison to a conventional minimally invasive implantation

Navigated versus conventional medial unicompartmental knee arthroplasty: Minimum 18 years clinical outcomes and survivorship of the original Cartier design

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is a viable option of treatment in case of osteoarthritis (OA) or avascular osteonecrosis (AVN) isolated to either the medial or the lateral compartment of the knee. The aim of this study was to retrospectively present clinical outcomes and survivorship at minimum 18 years follow up of a fixed bearing (FB) UKA comparing the results of conventional technique and navigation.

METHODS

Patients treated with a medial FB UKA between June 2003 and December 2006 were retrospectively evaluated. From March 2005 all UKAs were performed using a computer navigation system. Patients were divided into two groups: UKAs assisted by navigation (n-UKAs) versus standard UKAs (s-UKAs). For all patients, at final follow up, patient-reported outcome measures (PROMs) were collected: Western Ontario and McMaster Universities (WOMAC) score, Oxford Knee Score (OKS) and Forgotten Joint Score (FJS-12). Survival rate and outcomes were compared between groups.

RESULTS

Fifty-two patients were analyzed in this retrospective evaluation. All UKAs were medial and the tibial component was all polyethylene (AP) in 26 cases and metal backed (MB) in 26. Twenty-six UKAs were implanted with standard technique (AP 10, MB 16) and 26 assisted by a navigation system (AP 16, MB 10). Three patients (5.7%) underwent revision; the average time to revision was 140.7 months (standard deviation 81.2). Average follow up was 216.4 months (standard deviation 10.6). The survivorship of the implant was 94.4% at final follow up. Survivorship and PROMs were not different between groups.

CONCLUSIONS

This study showed excellent survivorship and outcomes at long term follow up of the original fixed bearing Cartier designed implant in both groups with equivalent survivorship and PROMs.

Referencing the Tibial Plateau With a Probe Improves the Accuracy of the Posterior Slope in Medial Unicompartmental Knee Arthroplasty

Background

There is currently no consensus on intraoperative references for determining the posterior tibial slope (PTS) in medial unicompartmental knee arthroplasty (UKA). The medial tibial plateau could serve as a direct reference for determining the native PTS through the placement of a hook probe in the anteroposterior direction of the medial tibial plateau. This study aimed to examine the accuracy of this new referencing method.

Methods

We consecutively performed 55 medial UKAs using our new method (study group), and the preoperative and postoperative PTS on lateral knee radiographs were examined. These outcomes were then compared with those of consecutive 50 medial UKAs performed using the conventional method (control group), which immediately preceded the start of the use of the new method.

Results

The correlation coefficient between the preoperative and postoperative PTS of the study group was larger than that of the control group (0.887 and 0.482, respectively). The mean implantation error of the PTS in the study group was smaller than that of the control group (-1.1° ± 1.3° and -3.0° ± 3.2°, respectively; P < .0001). The percentages of knees within 2° of implantation error were 73% and 34% in the study and control groups, respectively (P < .0001). The root mean square errors in the study and control groups were 1.7° and 4.3°, respectively.

Conclusions

The direct referencing method with a probe can significantly improve the accuracy of tibial sagittal alignment.

Comparison of computer-assisted navigated technology and conventional technology in unicompartmental knee arthroplasty: a meta-analysis

Background

Though unicompartmental knee arthroplasty (UKA) is a useful procedure to treat knee osteoarthritis, it remains a great controversial point as to if navigated systems are able to achieve better accuracy of limb alignment and greater clinic results. Current meta-analysis was conducted to explore if better clinical outcomes and radiographic outcomes could be acquired in the navigated system when compared with conventional procedures.

Methods

We identified studies in the online databases, including Medline, Embase, the Cochrane Library and Web of Science before May 2021. The PRISMA guidelines in this report were strictly followed. Our research was completed via Review Manager 5.4 software.

Results

Fourteen articles were included, involving 852 knees. The present meta-analysis displayed that the navigated system had remarkably improved outcomes in inliers of mechanical axis (MA) (P < 0.01), MA in the Kennedy's central zone (Zone C) (P = 0.04), inliers of the coronal femoral component (P < 0.01), inliers of the coronal tibial component (P = 0.005), inliers of the sagittal femoral component (P = 0.03), inliers of the sagittal tibial component (P = 0.002) and Range Of Motion (ROM) (P = 0.04). No significant differences were observed in Oxford Knee Score (OKS) (P = 0.15), American Knee Society Knee Score (KSS score) (P = 0.61) and postoperative complications (P = 0.73) between these 2 groups. Regarding operating time, the navigated group was 10.63 min longer in contrast to the traditional group.

Conclusion

Based on our research, the navigated system provided better radiographic outcomes and no significant difference in the risk of complications with longer surgical time than the conventional techniques. But no significant differences were found in functional outcomes. Because the included studies were small samples and short-term follow-up, high-quality RCTs with large patients and sufficient follow-up are required to identify the long-term effect of the navigated system.

Comparable incidence of periprosthetic tibial fractures in cementless and cemented unicompartmental knee arthroplasty: a systematic review and meta-analysis

PURPOSE

(I) To determine the incidence of periprosthetic tibial fractures in cemented and cementless unicompartmental knee arthroplasty (UKA) and (II) to summarize the existing evidence on characteristics and risk factors of periprosthetic fractures in UKA.

METHODS

Pubmed, Cochrane and Embase databases were comprehensively searched. Any clinical, laboratory or case report study describing information on proportion, characteristics or risk factors of periprosthetic tibial fractures in UKA was included. Proportion meta-analysis was performed to estimate the incidence of fractures only using data from clinical studies. Information on characteristics and risk factors was evaluated and summarized.

RESULTS

A total of 81 studies were considered to be eligible for inclusion. Based on 41 clinical studies, incidences of fractures were 1.24% (95%CI 0.64-2.41) for cementless and 1.58% (95%CI 1.06-2.36) for cemented UKAs (9451 UKAs). The majority of fractures in the current literature occurred during surgery or presented within 3 months postoperatively (91 of 127; 72%) and were non-traumatic (95 of 113; 84%). Six different fracture types were observed in 21 available radiographs. Laboratory studies revealed that an excessive interference fit (press fit), excessive tibial bone resection, a sagittal cut too deep posteriorly and low bone mineral density (BMD) reduce the force required for a periprosthetic tibial fracture to occur. Clinical studies showed that periprosthetic tibial fractures were associated with increased body mass index and postoperative alignment angles, advanced age, decreased BMD, female gender, and a very overhanging medial tibial condyle.

CONCLUSION

Comparable low incidences of periprosthetic tibial fractures in cementless and cemented UKA can be achieved. However, surgeons should be aware that an excessive interference fit in cementless UKAs in combination with an impaction technique may introduce an additional risk, and could therefore be less forgiving to surgical errors and patients who are at higher risk of periprosthetic tibial fractures.

LEVEL OF EVIDENCE

V.

What is the evidence for clinical use of advanced technology in unicompartmental knee arthroplasty?

BACKGROUND

With an aim of improving prosthesis survivorship of unicompartmental knee arthroplasty (UKA), use of computer-assisted technologies (CATs) such as robotics, has been on the rise to reduce intraoperative errors in surgical technique. In light of recent influx of CATs in the UKA, a review of these innovations will help providers to understand their clinical utility.

METHOD

A systematic literature search was performed following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines.

RESULTS

Among 19 studies comparing robot-assisted UKA with conventional UKA, only 32% were randomized control trials, 47% reported minimum mean follow-up of 2 years, and 21% evaluated prosthesis survival. Similar results were obtained for navigation-assisted UKA and UKA performed with patient-specific instrumentation.

CONCLUSION

While CATs seem to reduce the surgical errors in UKA, the evidence on the efficacy of any of the studied CATs to improve survivorship remains limited and there are issues related to cost-effectiveness, learning curve, and increase in operating time.

Lateral Unicompartmental Knee Arthroplasty

Lateral unicompartmental knee arthroplasty affords excellent functional results and implant survivorship for properly selected patients. More high-quality studies are necessary to determine whether expanded indications for medial unicompartmental knee arthroplasty also apply to lateral unicompartmental knee arthroplasty. Operative adjuncts such as robotics, custom implants, and navigation technology hold promise in minimizing the technical burden and unfamiliarity of lateral unicompartmental knee arthroplasty. Improvements in lateral-specific implants may translate to operational efficiency and improved outcomes, but few lateral-specific implants currently exist. Mobile-bearing devices have increased rates of failure due to bearing dislocation, and further studies are warranted to evaluate this complication with newer designs. Future registry and cohort studies should show medial unicompartmental knee arthroplasty and lateral unicompartmental knee arthroplasty separately to allow for better understanding of the nuances and technical differences between these uniquely different procedures.

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.

Improved Survival of Computer-Assisted Unicompartmental Knee Arthroplasty: 252 Cases With a Minimum Follow-Up of 5 Years

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an underutilized implant for medial tibiofemoral arthritis despite proven benefits in performance and reduced complications. This is likely related to registry recorded higher revision rates compared with total knee arthroplasty. It is our feeling that better component alignment resulting from the usage of computer-assisted surgery should improve longer-term functional results and survival of UKAs.

METHODS

Between August 2003 and June 2007, 265 medial UKAs were performed in 264 consecutive patients using navigation.

RESULTS

Eighty-eight women and 176 men with an average age of 51.7 (±4.63) years were assessed for function and survival over a follow-up period of 92.6 (63-120) months (7.7 years). The final survival rate over 5 years for this cohort was 97.6% at 5 years.

CONCLUSION

We conclude that computer-assisted UKA, to treat medial tibiofemoral joint arthritis, produces 5-year survival rates that are comparable with total knee arthroplasty.

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.

Is tibial cut navigation alone sufficient in medial unicompartmental knee arthroplasty? Continuous series of fifty nine procedures

PURPOSE

Our purpose was to assess medial unicompartmental knee arthroplasty with navigation alone for the tibial cut and limb alignment. We hypothesised that this technique could be used routinely in practice.

METHODS

Outcome measures were tibial cut orientation and residual varus. Six-month post-operative radiographs of 59 knees were assessed.

RESULTS

Tibial cut orientation was within 2° of planned in 70.2 and 76.3 % of knees in the coronal and sagittal planes, respectively (49.1 % in both), within 4° in 91.2 and 91.5 %, respectively (82.5 % in both). All coronal-plane errors were in varus. Excessive planed tibial slope was at risk of excessive varus of the tibial cut. The hip-knee-ankle angle was ≤179° in 81.4 % and the mechanical axis through Kennedy Zone 2 in 59.3 % of knees. Risk factors for inadequate varus were pre-operative hip-knee-ankle angle >176° and strictly articular varus.

CONCLUSIONS

Our results are not as good as previously reported with this technique, but taking into account the factors of failure identified, we could enhance the results.

Comparison of Outcome and Survival After Unicompartmental Knee Arthroplasty Between Navigation and Conventional Techniques With an Average 9-Year Follow-Up

BACKGROUND

Unicompartmental knee arthroplasty(UKA) has become a treatment of choice for many patients with isolated unicomparmental arthritis due to its specific advantages over total knee arthroplasty, but few studies have compared conventional and navigational UKA with similar instrumentation on mid- to long-term results. We investigated whether the use of imageless navigation can improve implant positioning and clinical outcomes of UKA at a long-term follow-up compared to the conventional technique.

METHODS

We prospectively studied clinical and radiological results in 68 patients with an average age of 64.0 years (range, 50 to 81 years) who received UKA between January 2003 and December 2005 using the conventional or navigational technique. Clinical evaluations were performed preoperatively and the last follow-up included knee range of motion, Hospital for Special Surgery (HSS) scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and Visual Analogue Scale (VAS) pain score. For radiologic evaluation, the mechanical alignment of the lower limb was measured using mechanical femoro-tibial angle (mFTA) and Kennedy protocol.

RESULTS

After an average 9-year follow-up (range, 7.4 to 10.8 years), the navigation group showed better coronal alignments of the components, fewer radiological outliers and better clinical scores, but similar estimated 10-year prosthesis survival rates.

CONCLUSION

This study indicates that the use of navigation significantly contributes to the desired mechanical axis and improved component placement as compared to the conventional technique.

LEVEL OF EVIDENCE

Prospective comparative study, Level III.

Improved accuracy in computer-assisted unicondylar knee arthroplasty: a meta-analysis

PURPOSE

Inaccurate implantation rates of up to 30 % have been reported in cases using the conventional technique for implantation of a unicompartmental knee arthroplasty. Navigation should permit a more precise implantation, and several studies have investigated its role, albeit with a limited number of patients and inconsistent results. The aim of this meta-analysis was to compare risks of unsatisfactory outcomes in patients with navigated and conventional technique.

METHODS

An electronic search was performed, and ten studies were eligible and included in the meta-analysis, with a total of 258 prostheses implanted with the navigated technique and 295 with the conventional one. The following items were analysed: radiological positioning of the femoral and the tibial component in the AP and lateral view, radiological analysis of the tibiofemoral mechanical axis and the difference in operating time between the two groups. Relative risks (RR) were calculated from the reported percentages of implants outside the optimal ranges defined by the manufacturers or the study groups. Natural logarithms of the relative risks were pooled by means of random effects models.

RESULTS

For all the analysed radiological parameters, the RR of measurements outside the optimal ranges were less than 1 in the navigation group suggesting a reduction in the risk of outliers with navigation. The average operating time in the navigated group was 15.4 min (95 % CI: 10.2-20.6) longer than in the conventional group.

CONCLUSION

The meta-analysis shows that the use of navigation systems in UKA leads to a more precise component position. Whether the more accurate position in UKA results in a better clinical outcome or long-term survival is yet unknown. Nevertheless, as a precise implant position appears to be beneficial, the use of navigation should be recommended for UKA. The limits defined by the manufacturers for an optimal positioning are not consistent.