An alternative patellar fracture fixation: a biomechanical study.

OBJECTIVES

The purpose of this study is to compare open reduction and internal fixation of the patella with a locking plate and tension-band construct (PF) versus cannulated screws and tension-band fixation (SF). The hypothesis is that both constructs will have similar failure loads with simulated extension loading.

METHODS

Transverse patellar fractures were created in 10 cadaveric pairs of legs and were fixed with either PF or SF. Dual-energy X-ray Absorptiometry (DXA) scans of all calcanei measured bone mineral density (BMD). Using an MTS 810 servohydraulic testing machine, each leg cycled to full extension 10 times before loading to failure. A differential variable reluctance transducer measured the distraction of the patella. Data were analyzed using paired t test analysis and bivariate analysis for Pearson correlation coefficients.

RESULTS

There was no difference in the BMD between the PF and the SF groups (P = 0.367). No measurable differences occurred during the 10 cycles, and load at clinical failure was not significantly different between the 2 fixation groups (P = 0.38). Stiffness during the final loading cycle was significantly higher for the SF group (P = 0.008). Ultimate strength of fixation was significantly higher in PF group (P = 0.048). BMD was not correlated to the ultimate strength of SF (P = 0.112), but was correlated for PF (P = 0.025).

CONCLUSIONS

Based on our results, PF provides comparable strength to SF, and it seems to be a safe and effective alternative to the current gold standard.