Total Knee Arthroplasty and Intra-Articular Pressure Sensors: Can They Assist Surgeons with Intra-Operative Decisions?

Analytical validation studies suggest that intra-operative pressure sensors demonstrate 'moderate' to 'good' intra-observer reliability and 'good' to 'excellent' interobserver reliability throughout the flexion arc. However, there are important errors associated with measurements when devices are used out-with the stated guidelines and clinicians should be aware of the limitations of these devices in isolation. Current evidence regarding patient benefit is conflicting. Despite positive early results, several prospective studies have subsequently failed to demonstrate significant differences in overall survival, satisfaction, and patient-reported outcome measures within 1 year of surgery. Surgeon-defined soft tissue stability appears to be significantly different from the absolute pressures measured by the intra-operative sensor. Whilst it could be argued that this confirms the need for intra-articular sensor guidance in TKA; the optimal 'target' balance remains unclear and the relationship with outcome in patients is not determined. Future research should (1) identify a suitable reference standard for comparison; (2) improve the accuracy of the sensor outputs; and (3) demonstrate that sensor-assisted TKA leads to patient benefit in patient-reported outcome measures and/or enhanced implant survival.