Biomechanical Evaluation of Transverse Patella Fracture Fixation Using Headless Screws: A Comparison of Suture Versus Cable as a Tension Band.

OBJECTIVES

To explore the performance of headless screws with FiberWire Suture as a tension band and headless screws with a mini-cable tension band in patella fixation.

METHODS

A transverse osteotomy was created in 6 matched pairs of fresh-frozen cadaver knee joints. One knee was randomly assigned to receive fixation with headless screws plus a cable tension band while the other was fixed with headless screws plus a suture tension band. Using a servo-hydraulic material testing system, the specimens were first tested nondestructively under 20% of the reported mean failure load with a standard technique of cannulated screws with tension band wiring. The specimen was then loaded to 1000 N to test the construct's failure strength. All tests were run under displacement-control with loading threshold. A motion analysis system was used to track the interfragmentary motion to assess fixation stability.

RESULTS

In the nondestructive loading test, gap displacement under 150 N was 0.10 mm or less for 11 of 12 specimens, and the difference between the 2 groups was not statistically significant. In the destructive test, 3 of 12 specimens maintained reduction (gap <2 mm) at the maximum load of 1000 N. Of the failed specimens, the mean strength was 648 ± 185 N for suture and 784 ± 228 N for cable.

CONCLUSIONS

There was no significant difference in fixation strength or subfailure fragment displacement between the suture and cable tension band techniques when using headless screws.