Mechanical characterization of the Robert Jones bandage under cyclic compression-bending: An in vitro experimental...

To assess the rigidity of Robert-Jones Bandage (RJB) used to stabilize a standardized in vitro fracture model, under cyclic compression/bending.

In vitro cyclic testing study.

wooden rods divided into two segments of identical length by a Cardan Joint enclosed in a thick foam tube and supported by a RJB.

Part 1: incremental loading applied to 6 specimens in successive stages of 50 N from 5 to 150 to 5-300 N with 3000 cycles per stage. Part 2: 9 specimens were loaded at 150 N (5-150 N) during 60,000 cycles.

The Wilcoxon signed-rank test was used to compare data obtained at 10,000 and 60,000 cycles.

In part 1, 6/6 specimens withstood 150 N for 3000 cycles. Three specimens endured an additional 3000 cycles at 200 N, 2 withstood 250 N for another 3000 cycles, and 1 tolerated 300 N. In part 2, 9/9 specimens withstood 150 N for 60,000 cycles, with displacements ranging from 0.102 mm to 0.309 mm (mean 0.179 ± 0.069 mm) and a median rigidity of 897 ± 375 N/mm. No specimen reached the fixed displacement limit of 2 mm after 60,000 cycles. No statistically significant difference was found between the results at 10,000 and 60,000 cycles (p = 0.129).

The Robert-Jones Bandage showed consistent rigidity under prolonged cyclic loading in an in vitro fracture model.

While this in-vitro model cannot replicate the influence of soft tissues, joint motion, or multidirectional physiological forces, the findings suggest that a properly applied Robert Jones bandage may provide short-term mechanical support to a long-bone fracture prior to definitive stabilization. However, clinical applicability should be interpreted with caution given the inherent limitations of the experimental setup.