Is Force Control a safe and efficient surgical technology for thoracolumbar fusion surgery? A Post Market Clinical Follow-up Study.

Background: Early screw loosening, a relevant complication after posterior thoracolumbar fusion, indicates high mechanical stress during rod connection. Force Control is a surgical technology that goes beyond the usual to identify, control and minimize intended and unintended, usually unnoticed forces to achieve the most stressless fixation. Optimized, extremely lightweight instruments support this principle on part of the pedicle screw system (PSS). The study objective is to evaluate the safety and efficacy of a novel PSS for Force Control fusion surgery.

Methods: In this literature-controlled observational study, patients underwent surgery with a PSS that supports Force Control. Safety is demonstrated 1 year postoperatively by non-inferiority in screw loosening rate and efficacy by non-inferiority in ODI improvement. Secondary endpoints: 2-year ODI, spine-related AEs and outcomes. Statistical significance p<0.025 (Bonferroni correction 0.05/2).

Results: 75 patients enrolled, main diagnoses were trauma (73.3%), spinal stenosis (17.3%), degenerative disc disease (6.7%). Screw loosening rate at 1-year was 2.7%, being not inferior (p=0.005) to the control group at 9.2%. Mean ODI improvement of 49.3 showed non-inferiority (p<0.001) versus 35.2 in the control group. Mean 2-year ODI was 19, mean VAS back pain improved from 80.3 to 24.1 (3-month) and 21.6 (1-year). The implant-related revision rate was 4.1%.

Conclusions: Force Control, aiming to go beyond the familiar by controlling intended and unintended forces to achieve the most stressless fixation, is a safe and efficient method. Lightweight instruments are designed to allow identifying, controlling and reducing mechanical stress. Patients benefit from Force Control regarding screw loosening and clinical outcome.