Abstract
Introduction
During its conception, Ilizarov advocated a fine wire tension of between 900N and 1200N for circular frame construction. Wire tension can be achieved via a tensioning device or ‘Russian tensioning’ (a fixed wire lengthening around a bolt). There is limited information on the latter technique. This study aimed to explore the tensions achieved via Russian tensioning and report the impact of a second wire on construct tension.
Materials and Methods
A single 160mm stainless-steel ring was constructed, then 1.8mm stainless steel wires secured using a Russian fixation bolt and Russian tensioned with a 2nd bolt. The angle subtended by tensioning using the 2nd bolt was measured using a goniometer. Angles of 45°, 70° and 90° were repeated in triplicates, with wire tension measured using a calibrated tensiometer. A 2nd orthogonal wire was placed on the opposite side and tensioned to the same angle. Tensions of both wires were remeasured and recorded. Statistical comparison using unpaired t-tests was used to compare mean tensions. A value of p<0.05 was considered significant.
Results
Russian wire tensioning at all angles was insufficient to achieve the target range of 900–1200N (range 99–110N). The addition of a second orthogonal wire changed frame dynamics such that a 90° angle resulted in both wires achieving adequate tension (mean 1143N, SD 307N). Increases were significant across all tensioning angles (p–<0.002) however only biomechanically relevant for 90°.
Conclusions
Russian tensioning is insufficient with a single wire, however the addition of an orthogonal wire increases tension in both wires, which reaches the target range at 90° deflection. This phenomenon is explained by force transmission initially into ring deflection, which is then balanced out by the second wire. Further study of this phenomenon using wire tensioners is warranted, and also the impact of non-orthogonal wire constructs.
