gms | German Medical Science

Objectives/Interrogation: In tendon surgery early mobilisation is the key to have superior outcomes. It reduces adhesion formation, improves tensile strength, vascularity and cellularity of the repair site. The side-to-side (STS) technique was developed to provide the adequate strength to allow early mobilisation. The original description suggests 50 mm overlap region. The idea of this study was to measure the strength and stiffness of STS sutures with smaller overlap region, to find the minimal length needed. We tested the Pulvertaft (PT) repair and three types of the STS repair with 50 mm, 40 mm, 30 mm overlap region.

Methods: Flexor digitorum profondus tendons were freshly harvested from mangalica pig front legs. We used standard 7 mm wide tendons. For the PT technique we used the 3 weave modification with cross-stitch sutures at the insertions, and 2 stitches at both ends. For the STS repair we measured the wanted overlap region, secured it with two end stitches, and made the running cross sutures on both sides of the repair. All mechanical tests were carried out using a fatigue testing machine (Instron8874). The free ends of the repairs were wrapped in wet gauze and secured with clamps. All tendons were pre-conditioned, were allowed to stress-relax for 30 secs, and then were elongated to failure. The tendons were kept wet with physiological saline solution. We measured load of first failure, ultimate load and repair stiffness.

Results and Conclusions: All but one failure occurred in the repair region, one occurred at the clamp. PT repairs failed with the graft tendon pulling out of the recipient. STS repairs failed with longitudinal shearing of the tendon fibers. The ultimate load (highest force till failure) was significantly higher at all of the STS repairs than the PTs. There was no significant difference between the various STS repairs at ultimate load. The stiffness (slope of the linear region of the load deformation curve) of all the STS repairs were higher than the PT repairs.

The main result of this study was that the STS suture method tested here produced stronger and stiffer repairs compared to the tested variation of the PT repair. The 30mm overlap STS suture strength is not significantly lower than the STS repair with the 50 mm overlap. All tested repairs provide more than enough strength to allow early mobilisation. STS repairs offer more strength, more stiffness, thinner reconstruction site than the PT repair. The 30 mm overlap region also can be used on shorter tendons which otherwise would need grafting.