The Correlation Analysis Between the Pedicle Screw Placement Palpation and Torque.

Background: This study endeavored to investigate the influencing factors of pedicle screw torque measured during surgery and the correlation between manual palpation scores and screw torque.

Methods: This investigation was a prospective study designed to gather data from patients who underwent spinal internal fixation performed by the same surgical team at the Department of Orthopedics, affiliated with the First Hospital of Guangzhou University of Chinese Medicine, spanning from January 2020 to September 2023. The sample comprised 51 individuals (18 males and 33 females; mean age: 60.78±11.48 years). All participants underwent bone mineral density (BMD) and comprehensive radiological testing to evaluate the affected spinal segments. Intraoperatively, parameters such as the surgeon's tactile perception, a visual analog scale for manual palpation, and peak screw torque values were documented. Patients were subsequently stratified into 3 categories based on the resistance encountered during screw placement. Demographic variables (age, height, and weight) and BMD measurements of patients within each category were compared. Factors exhibiting significant differences were subjected to multivariate logistic regression analysis. Concurrently, the relationship between manual palpation scores and torque values was examined.

Results: The results of the univariate analysis indicated that age (P = 0.042), height (P = 0.047), BMD of the lumbar (P < 0.01), BMD of the femoral neck (P = 0.02), BMD of the hip (P = 0.02), and P1NP (P = 0.044) were statistically significant. The results of multivariate logistic regression analysis revealed that BMD of the lumbar was an independent influencing factor for torque (P=0.000<0.05). Additionally, the manual palpation score and torque value of group A were significantly lower than those of the other 2 groups (P < 0.001). There was a significant positive correlation between the intraoperative screw placement palpation and torque.

Conclusions: The BMD of the lumbar is an independent factor that influences the measured torque applied to pedicle screws during surgery. A significant and robust positive correlation exists between the intraoperative screw placement tactile sensation and the torque experienced. It is advisable to reinforce the screw channel with bone cement when the tactile score is ≤2.5 and the torque is ≤ 1.3 Nm.