Biomechanical Evaluation of Suture Tape Versus Metallic Wire With Cannulated Screws Tension Band Fixation For Transverse Patella Fractures: A Biomechanical Study.

Background: Transverse patella fractures requiring surgical fixation are typically treated with a tension band construct using metal wire. This technique is associated with high rates of complications and reoperation. Alternative fixation technique utilizing non-absorbable suture materials have been introduced. This biomechanical study aims to compare the stability of two tension band constructs, both utilizing headed cannulated lag screws, with either suture tape or traditional metal wire under cyclic load conditions, simulating repetitive physiological stress.

Methods: Six matched pairs of fresh frozen cadaveric knees were obtained for testing. A standardized transverse patellar osteotomy (AO/OTA 34C1.1) was created in each to simulate a simple transverse patella fracture. Each pair was repaired using a tension band construct with headed cannulated screws, randomized to fixation with either suture tape or metal wire. All specimens underwent cyclic loading from 0 to 90 knee flexion at a frequency of 0.2 Hz for up to 1000 cycles. Two displacement transducers were used to measure real-time fracture gap displacement during testing from the start of testing and until clinical fixation failure. Clinical failure is defined as fracture gap displacement > 3 mm.

Results: Clinical failure occurred in 5 of 6 specimens (83%) in the suture tape group, with a mean of 296±433 cycles. In the metal wire group, 4 of 6 specimens (67%) experienced clinical failure, with a mean of 421±461 cycles. There was no statistically significant difference in cycles to failure between the two groups (p=0.29). Kaplan-Meier survival analysis demonstrated a 500-cycle survival rate of 33% (95% CI: 0%-71%) for both groups.

Conclusion: Both constructs may be considered viable options for the surgical treatment of simple transverse patella fractures.

Level of evidence: V.