Direct Radiological Visualization of Loading on Four Flexor Tendon Repair Suture Configurations

To study the deformation of 4 suture configurations used in flexor tendon repair using fluoroscopy.

All flexor tendon repair techniques have a longitudinal component, a link component, and/or a transverse component. We had previously described 4 types of link components, namely an arc (grasping loop), a simple loop (locking loop), a complex loop, and a knot. The effect of loading on suture configurations using each of these link components was tested in flexor tendon from the first ray of porcine feet. Forty flexor tendons were divided into 4 groups of 10 each, and one-half of a tendon repair was simulated on each group using 0.5 mm stainless steel wire. The tendons were mounted on a materials testing machine, and tensile force was applied until failure. The deformation of the suture within the tendon substance was observed using an image intensifier, and the maximal load to failure was measured.

The loading of the suture led to unraveling of the suture in an arc, constriction and unraveling in a simple loop, and initial constriction with no further change of the construct in the complex loop with no change in the knot design. The mean pullout strength of the complex loop was statistically greater than all the other 3 designs.

Each of the link component designs demonstrated unique deformation characteristics. The complex loop design had the strongest grasping ability.

This study identified the differences in the deformation characteristics of the 4 types of link components used in flexor tendon repair. This knowledge may allow for the development of better flexor tendon repair techniques and the adoption of a more precise classification of flexor tendon repair techniques.