The Role of the Tourniquet and Patella Position on the Compartmental Loads During Sensor-Assisted Total Knee Arthroplasty

Abstract Background An inflated tourniquet may diminish the natural excursion of the extensor mechanism and alter compartmental loads, affecting the surgeon's ability to accurately assess ligament balance during total knee arthroplasty (TKA). In addition, patella position (reduced, lateralized, or everted) has also been known to affect compartmental loads. This study used intraoperative sensing to assess how a combination of tourniquet inflation and patella position may affect medial and lateral compartmental loads during sensor-assisted TKA. Methods Fifty-six patients (13 men) with a mean age of 66 years (standard deviation, 8.66) and mean BMI of 31 kg/m 2 (standard deviation, 6.66) undergoing primary cemented TKA for primary osteoarthritis were enrolled. After final prosthetic implantation, with the tourniquet inflated, medial and lateral compartment loads were obtained in the 10°, 45°, and 90° of flexion with the patella in reduced, lateralized, or everted positions. The tourniquet was deflated and this process repeated. Surgeons were blinded to the values as to not influence medial and lateral stressing of the knee. Linear regression was used to evaluate absolute loads. Results Tourniquet inflation did not significantly alter compartmental loads regardless of knee flexion or patella position. Lateral compartment loads significantly increased as the patella moved from the reduced, to the lateralized, to the everted position with the tourniquet inflated or deflated. Conclusion Tourniquet inflation did not significantly alter compartmental loads during sensor-assisted TKA. However, irrespective of tourniquet use, a lateralized or everted patellar position significantly increased lateral compartment loads.