Robot Assisted Total Knee Arthroplasty and Navigation Assisted Total Knee Arthroplasty : A Comparative study with a focus on Severe Varus Deformities.

Robot Assisted Total Knee Arthroplasty and Navigation Assisted Total Knee Arthroplasty : A Comparative study with a focus on Severe Varus Deformities.

Rajesh Maniar, INDIA Adit Rajesh Maniar, MBBS, MS Orthopaedics, DNB Orthopaedics, INDIA Akshay Nayak, M.B.B.S, M.S , INDIA Ishan Khanna, MBBS, MS, INDIA Pranav Shere, MS,DNB , INDIA Anish Nandkumar Tawde, M. S. Orthopaedics , INDIA

Lilavati Hospital & Research Center, Mumbai, Maharashtra, INDIA


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Summary: Robotic assisted total knee arthroplasty can add further benefit to navigation assisted total knee arthroplasty.


Introduction

As the demand for primary total knee arthroplasty(TKA) increases, newer technology like robot assisted TKA(RTKA) has gained recent popularity. Computer navigation assisted TKA(NTKA) has been used for the past two decades for more accurate implant positioning as compared to conventional-jig based TKA. RTKA has the added advantage of a robotic arm completing bony cuts to reduce technical errors. Additionally, the ability to implement alternative alignment philosophies allowing for better component positioning to balance gaps may reduce the need for soft tissue releases, especially in severe deformities. To the best of our knowledge there are no studies comparing RTKA to NTKA, specifically in tackling severe deformities. The aim of our study was to compare the clinical outcomes between RTKA and NTKA in all patients and specifically in those with severe varus deformity.

Methods

We prospectively followed all patients undergoing primary TKA at a single tertiary care center by a single surgeon between January 2023 until December 2023. We identified 179 consecutive TKA, 90 in NTKA group and 89 in RTKA group. Of these 122 (68.1%) had a severe varus (>10º) deformity, 62 in NTKA group and 60 in RTKA group. The surgeon was experienced in NTKA for two decades before transitioning to RTKA in January 2023, with the patients in this study being the first RTKA performed by the surgeon. All patients received a posterior stabilized cemented implant with patella resurfacing, using a functional alignment strategy of 3º limit from neutral for overall coronal alignment. The intraoperative soft tissue release(STR) rate, i.e. pie crusting or release of the superficial medial collateral ligament was recorded. Clinical outcomes were assessed using Forgotten Joint Score (FJS) and New Knee Society Score (NKSS). We judged satisfaction with light activities at 1 year using a 5 point Leikert scale with patients classified as satisfied if the response was either satisfied or very satisfied. We had 93.8% follow-up at 1 year post TKA. Comparison between NTKA and RTKA was made in the total cohort and in severe (> 10º) varus cohort. Student T test, Mann Whitney U test and Fisher Exact test were used for statistical analysis.

Results

There were no differences(p>0.05) in preoperative general demographics. For the severe varus cohort, there was no difference(p>0.05)) in severity of the deformity between the two groups preoperatively and postoperatively while the STR rate was significantly lower(p=0.02) in the RTKA group as compared to the NTKA group(33.3% and 54.8 % respectively). At 3 months post TKA, for the entire cohort, the improvement in FKS(p=0.03), and NKSS(p=0.04) was significantly higher in the RTKA group. At 1 year, for all patients, the satisfaction rate was significantly higher(p=0.04) in the RTKA group as compared to the NTKA group(94.1% vs 84.3% respectively).

Conclusion

Compared to NTKA, when performing RTKA, we observed a reduced requirement of soft tissue release in patients with severe varus deformity while having the same coronal alignment pre and post operatively. Patients undergoing RTKA seem to have an improved functional recovery at 3 months post TKA and higher satisfaction rates at 1 year post RTKA, but further larger studies in a different population are required to confirm the results of this study. Patients with a severe varus deformity had excellent satisfaction rates (94.7%) when undergoing RTKA.