Abstract
Purpose
The purpose of this study was to compare intercompartmental loads and the proportion of knees with unbalanced loads after tensiometer-assisted balancing (TAB) between cruciate retaining (CR) and posterior stabilized (PS) total knee arthroplasty (TKA).
Materials and Methods
Forty-five CR and 45 PS TKAs using a single prosthesis were prospectively evaluated. The intercompartmental loads in 10°, 45°, and 90° of knee flexion after TAB were evaluated; the proportions of load imbalance (medial load – lateral load >15 lbs) in each flexion angle after TAB were investigated. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TAB were calculated, with the sensor-balanced loads considered the reference standard.
Results
The average loads of the medial compartment in CR TKA were greater than the adequate load (55 lbs) in every knee flexion angle; those of PS TKA were <55 lbs. The proportions of the load imbalance were >50% in every knee flexion angle in both CR and PS TKA (CR >64.4% and PS >57.8%), and there was no difference between the groups (p > 0.515). The sensitivity, specificity, PPV, and NPV of TAB were 91.7%, 66.7%, 57.9% and 94.1%, respectively, in CR, and 100%, 62.5%, 40 %, and 100%, respectively, in PS TKA.
Conclusions
The appropriate load balancing from the tensiometer seemed to be difficult in both CR and PS TKA. The intraoperative load sensor had a role in accurate load balancing to overcome the poor PPV of the tensiometer in both types of TKA.
