Incidence and Risk Factors for Facet Joint Violation in Open Versus Minimally Invasive Procedures During Pedicle Screw Placement in Patients with Trauma.

OBJECTIVE: A possible risk factor for premature facet joint degeneration or adjacent segment degeneration after surgical treatment of spine fractures is facet joint violation (FV) during insertion of pedicle screws. The aim of this study was to determine risk factors for FV in the thoracic and lumbar spine after minimally invasive screw insertion or open instrumentation (OI).

METHODS: A retrospective analysis of all patients with spine fractures requiring posterior stabilization was performed. After patients were allocated to the thoracic/lumbar group, FV was defined as an involvement caused by the positioning of a pedicle screw and its severity as determined by computed tomography was assessed by using a customized scoring system. Gender, age, and body mass index as well as segmental facet joint angle and the instrumentation system used (side-loading [SL] vs. top-loading) were considered as individual factors.

RESULTS: In total, 1099 pedicle screws were evaluated and an FV was identified in 433 instrumentations (39.0%). OI was used in 61.1% (n = 671) and an SL system was inserted in 45.0% (n = 494). In both, the thoracic (odds ratio [OR], 1.663; 95% confidence interval [CI], 1.119-2.472; P = 0.012) and the lumbar spine (OR, 0.494; 95% CI, 0.317-0.771; P = 0.002), OI was associated with a lower risk of FV. The violation rate was significantly higher when using a SL system (thoracic spine: OR, 1.822; 95% CI, 1.163-2.854; P = 0.009; lumbar spine: OR, 0.311; 95% CI, 0.203-0.477; P ≤ 0.001).

CONCLUSIONS: FV is a common complication after thoracic and lumbar spine surgery. Although both, the SL instrumentation and a minimally invasive procedure increases its occurrence, the patient characteristics do not affect the rate of FV.