Abstract
Aims
Compression and absolute stability are important in intra-articular fractures such as transverse olecranon fractures. This biomechanical study aims to compare tension band wiring (TBW) with plate fixation by measuring compression within the fracture.
Methods
A cross-over design and synthetic ulna models were used to reduce variation between samples. Identical transverse fractures were created using a 0.5mm saw blade and cutting jig. A Tekscan(tm) force transducer was calibrated and placed within the fracture gap. Twenty TBW or Acumed(tm) plate fixations were performed according to the recommended technique.
Compression was measured while the constructs were static and during simulated elbow range of movement exercises. Dynamic testing was performed using a custom jig reproducing cyclical triceps contraction of 20N and reciprocal brachialis contraction of 10N. Both fixation methods were tested on each sample. Half were randomly allocated to TBW first and half to plating first. Data was recorded using F-scan (v 5.72) and analysed using SPSS(tm) (v 16). Paired T-tests compared overall compression and compression at the articular side of the fracture.
Results
The mean overall compression for plating was 819N (+/− 602N 95%CI), TBW overall compression: 77N (+/−19N 95%CI) (P=0.039). Articular side compression for plating: 343N (+/− 276N 95%CI), TBW: 1N (+/− 2N 95%CI). (P=0.038)
During simulated movements, overall compression reduced in both groups: TBW -14N (+/−7N) Plating -173N (+/−32N) and no increase in articular side compression was detected in the TBW group.
Conclusion
Precontoured plates such as the Acumed(tm) olecranon system can provide significantly greater compression, compared to TBW in transverse olecranon fractures. This was significant for compression over the whole fracture surface and specifically at the articular side of the fracture. Also, in TBW, overall compression reduced and articular side compression remained negligible during simulated triceps contraction, challenging the tension band principle.
