Strength of the Joshi External Stabilising System.

PURPOSE To conduct an in vitro strength test for the Joshi External Stabilising System (JESS) for stabilisation of tibial fractures using a cadaveric tibia and steel rods. METHODS The configuration of the JESS specimens was based on a 62-year-old man with a metaphyseal tibial fracture. Two types of JESS specimens were prepared, using either the tibia of an average male adult cadaver (n=1) or stainless steel cylindrical rods (n=3). The strength of the JESS rather than that of the rods was measured using a universal testing machine. The axial compressive load was gradually increased at 1 mm/min to 35 N. Axial deformation of the fracture fragment was recorded. Each experiment was repeated 3 times in identical manner. A finite element analysis of the JESS was developed. The axial compressive loads and corresponding interfragmentary displacement in the experimental specimens and in the finite element analysis were compared. RESULTS The mean strength of the JESS was 32.5 N/mm in experiments and 35.3 N/mm in finite element analysis; the difference was 8.4%. The interfragmentary displacement was directly proportional to the axial compressive load. CONCLUSION The strength of the JESS is one fourth of that of the Ilizarov fixator, and therefore not suitable for full load bearing activities.