Abstract
Purpose
The purpose of the present study was to evaluate the intercompartmental loads with a sensor placed on implants after conventional gap balancing during total knee arthroplasty (TKA) with a tensiometer.
Methods
Fifty sensor-assisted TKA procedures were performed prospectively between August and September 2018 with a cruciate-retaining prosthesis. After applying a modified measured technique, conventional balancing between the resected surfaces was achieved. The equal and rectangular flexion–extension gaps were confirmed using a tensiometer. Then, the load distribution was evaluated with a sensor.
Results
The average load of the medial compartment was greater than that of the lateral compartment in both the flexion and extension of the knee. The proportion of medial–tight coronal load imbalance (medial load – lateral load ≥ 15 lb) was 50% in the extension and 28% in the flexion positions, respectively (p = 0.035). The loads in each medial and lateral compartment increased with extension of the knee; of note, the amount of increase was higher in the medial compartment (9.7 lb vs. 4.0 lb; p < 0.001). The proportion of the extension–tight sagittal load imbalance (extension load – flexion load ≥ 15lbs) was 34% in the medial compartment and 4% in the lateral compartment (p < 0.001).
Conclusions
Coronal and sagittal load imbalances existed as determined by the sensor even after the achievement of appropriate conventional gap balance. The use of an intraoperative load sensor offers the advantage of being able to directly evaluate the load on TKA implants following surgery.
