Sensor technology vs manual ligament balancing - How good are we at balancing primary total knee replacements?

Abstract

Introduction: Technological advances have allowed for the development of sensors that are designed for use in total knee replacement (TKR) that aim to improve post-operative results. The Verasense Knee System (OrthoSensor Inc., Dania Beach Florida) is a sensor system which replaces conventional tibial insert trials that can provide quantitative measures of pressures in the medial and lateral tibiofemoral compartments of the knee. Methodology: 25 consecutive total knee replacements were performed by a single surgeon. Ligament balancing was performed until the surgeon was satisfied that the knee was balanced using the conventional techniques. Pressure measurements were then made using the sensor. 25 matched patients that underwent TKR by the same surgeon served as the control group. Post-operative lower limb mechanical alignment, satisfaction levels, ROM, KSKS, KSFA scores and New Knee Society satisfaction scores were undertaken at 6 weeks, 3 months and 6 months after the operation. Results and Analysis: 68% of knee replacements performed were found to be quantitatively balanced after insertion of the sensor. Mean body weight and BMI of unbalanced knees was significantly greater compared to those that balanced (62.3 v.s. 73.2 kg, p=0.046 and 26.1 v.s. 32.1, p=0.048). No significant difference was found between the two groups for rehabilitation outcomes, satisfaction scores and mechanical alignment. Discussion and Conclusion: Conventional means of determining ligament balance can achieve quantitatively balanced total knee replacements in the majority of patients without need for further corrective measures. No short-term benefit was found with the use of this sensor technology.