# Robotic Total Knee Replacement: Single-Centre, Prospective, Non-Randomised Comparative Study Comparing Restricted Kinematic Alignment Combined with a Load Sensor Versus Functional Alignment

## TL;DR

This study compared two robotic-assisted knee replacement techniques and found no significant difference in patient outcomes after one year.

## Contribution

The first study to compare clinical outcomes between robotic-assisted functional alignment and restricted kinematic alignment with a load sensor in TKA.

## Key findings

- No significant differences in Knee Society Score or Forgotten Joint Score between the two groups at one year.
- Clinical outcomes in the rKA/sensor group were similar to prior studies using rKA without robotic assistance or a load sensor.
- The study reported clinical outcomes for functional alignment for the first time.

## Abstract

Background: Total knee arthroplasty (TKA) is an effective procedure for symptomatic end-stage knee arthritis with good clinical and survivorship outcomes. However, up to 20% of patients report dissatisfaction following TKA. Recent studies have suggested that this may be at least partially due to suboptimal limb alignment or ligament imbalance. This study compared clinical outcomes at 1 year post-operatively (i.e., the 2011 Knee Society Score [KSS] and Forgotten Joint Score [FJS]) between two robotic-assisted personalised TKA techniques: functional alignment (FA) and an original technique combining restricted kinematic alignment (rKA) with a load sensor to achieve reliable ligament balancing (via bone re-cutting with a robotic arm). Methods: This single-centre, prospective, comparative study was performed at a robotic-assisted arthroplasty centre. The study population consisted of an FA group (43 patients) and rKA/sensor group (47 patients). Clinical outcomes were measured at 1 month post-operatively (visual analogue scale [VAS] pain score, flexion, range of motion [ROM], use of a mobility aid and stiffness) and at 1 year (2011 KSS, FJS, VAS, flexion and ROM). Results: There were no statistical significant differences in 2011 KSS or FJS at 1 year post-operatively between the two groups. Multivariate analysis showed no independent association of either technique with the 1-year follow-up KSS Objective Knee Indicators score (adjusted beta coefficient (aβ) = −2.371 [−7.380; 2.638], p = 0.357), KSS Patient Satisfaction score (aβ = −2.522 [−6.887; 1.842], p = 0.262), KSS Patient Expectations score (aβ = 0.629 [−0.928; 2.186], p = 0.431), KSS Functional Activities score (aβ = −3.399 [−10.881; 4.082], p = 0.377) or 1-year follow-up FJS (aβ = −5.168 [−19.887; 9.550], p = 0.494). Conclusions: There were no significant differences between the FA and rKA/load sensor groups in the 2011 KSS or FJS at 1 year post-operatively. To our knowledge, this is the first study to compare clinical outcomes between robotic-assisted FA TKA and rKA TKA. Clinical outcomes in the rKA/sensor group were similar to previous studies using rKA without robotic assistance or a load sensor. This was also the first report of the clinical outcomes of FA. The results need to be validated by larger scale studies to avoid potential type 2 errors.