[The effect of surgical washers used with olive K-wires on bone surface kinetics in external fixation: a...

In external fixation, the type and configuration of K-wires have a considerable effect on fixation stability. Indications for external fixation have recently increased in the treatment of various musculoskeletal pathologies in osteoporotic patients. This biomechanical study was designed to determine the effect of surgical washers used with olive wires on surface kinetics of the cortical bone.

The study included 32 tibiae obtained from one-year-old sheep. Samples were prepared from the proximal parts of the tibiae which were then divided into four groups equal in number. A 1.8-mm olive K-wire was inserted into the proximal metaphyseal regions of the tibiae. Except for the control group, surgical washers were used with olive K-wires in the three study groups, with diameters of 5 mm, 7 mm, and 10 mm, respectively. The samples were then placed in a specially designed servo-hydraulic universal testing machine for static tensile test at 10 mm/min.

The mean failure load was 806.9 N in the control group, compared to 1285.9 N, 1317.9 N, and 1345.9 N in the three groups in which 5-mm, 7-mm, and 10-mm surgical washers were used, respectively. While there were significant differences between the control and study groups (p<0.0001), failure loads did not differ significantly between the three study groups (p=0.574).

The use of surgical washers in combination with olive K-wires offers a significant advantage to increase stability and to decrease surface pressure. We recommend utilization of washers for external fixation surgery in osteoporotic patients and osteoporotic bone segments.