Risk of Neurovascular Injury during Screw Fixation of Tibial Tubercle Fractures in Pediatric and Adolescent Patients.

Objective  To review knee magnetic resonance imaging (MRI) scans for the analysis of the location of neurovascular structures (NVSs), and to define the risk of bicortical fixation. Methods  Distances between the posterior cortex and the popliteal NVSs were measured on the MRI scans of 45 adolescents (50 knees) at 3 levels (C1: center of the proximal tibial epiphysis; C2: 10 mm distal to the physis; and C3: 20 mm distal to the physis). The NVSs located between 5 mm and 10 mm from the incision were considered in a zone of moderate risk for damage, while those less than 5 mm from the incision were considered in a zone of high risk for damage, and those more than 10 mm from the incision were considered to be in a zone of low risk for damage. The independent Student t -test was used for the comparison of the NVS distance 0with gender, skeletal maturity, and the tibial tubercle-trochlear groove (TT-TG) distance. Values of p  < 0.05 were regarded as statistically significant. Results  The path of the C1 screw posed an increased risk of damage to the popliteal artery and vein compared with other screw paths ( p  < 0.001). The popliteal artery has a high risk of damage at the level of C1 (4.2 ± 2.2mm), and a moderate risk at C2 (9.6 ± 2.4mm), and the popliteal vein has a moderate risk at C1 (6.0 ± 2.7 mm), and a low risk at C2 and C3 (10.8 ± 3.1mm, and 12.05 ± 3.1mm respectively). The C3 position presented the lowest risk of damage to these structures ( p  < 0.001). The distance between the posterior tibial cortex and the posterior tibial nerve was < 15 mm at the 3 levels analyzed (C1: 11.0 ± 3.7 mm; C2: 13.1 ± 3.8 mm; and C3: 13 ± 3.9 mm). Conclusions  The present study clarifies that the popliteal vessels are at risk of injury during tibial tubercle screw fixation, particularly when drilling the proximal tibial epiphysis. Monocortical drilling and screw fixation are recommended for the surgical treatment of tibial tubercle fractures. Level of Evidence III  Diagnostic study.