The biomechanical evaluation of polyester as a tension band for the internal fixation of patellar fractures

We use a braided polyester suture in place of cerclage wire in tension band fixations. The objective of this study was to test the biomechanical prope rties of this technique. Sixteen cadaveric patellae were fractured and repa ired by modified tension band fixation. Eight were fixed using eighteen gau ge stainless steel mire as a tension band and eight using braided polyester All specimens were subjected to tensile testing. Polyester was 75.0% as st rong as wire. For dynamic testing, the patellae of seven cadaveric knees we re fractured and then fixed with polyester tension bands. These were mounte d in a device capable of extending the knees from 90 degrees to neutral aga inst an applied force. None of the fixations failed. Three of the specimens fixed using 18 gauge stainless steel wire were compared with three fixed u sing polyester over 2000 cycles of knee flexion and extension. Polyester pe rformed as well as wire. We conclude that polyester is an acceptable altern ative to wire in tension band fixation.