In-vitro comparison of the lengthening and biomechanical properties of three tendon lengthening techniques

Clinically, the Z-plasty lengthening is the only method used in the upper extremity, whereas several different techniques such as the Vulpius and Baker are used in the lower extremity. In this study, the usage of the modified Vulpius and Baker tendon lengthening techniques in the upper extremity was investigated.

Vulpius and Baker techniques are modified by changing their application site in 90 sheep fore-limb deep flexor tendons using three randomly divided groups. Z-plasty, V-Y-plasty (Modified Vulpius) and U-T-plasty (Modified Baker) techniques were used in groups I to III, respectively. Their elongation and biomechanical properties were compared.

The Z-plasty technique provided significantly greater lengthening than the other two techniques, followed by the U-T-plasty technique. Failure load of the U-T-plasty technique was 60.7% higher than the Z-plasty technique and 45.4% higher than the V-Y-plasty technique. Repairs with the U-T-plasty and V-Y-plasty techniques were significantly stiffer than the repairs with the Z-plasty technique.

The U-T-plasty technique may be a good alternative to the Z-plasty technique because of its easy application and better biomechanical properties, especially in cases that need moderate-sized elongation and early mobilization. But the restorative properties of this technique need to be observed on an in-vivo model.