Purpose The aim of this study was to investigate the effects of early active movement on the area repaired with three different suture techniques used in extensor tendon injuries in zone IV. Materials and Methods A total of nine cadaver’s 35 extensor tendons from 9 intact upper extremities were used in this study. The proximal and distal borders of the extensor tendons in zone IV were marked. The distance between the proximal and distal border was measured with a 0.5 mm precision tape measure and the mid-point was marked. Intertendinous connections were dissected and loop sutures were prepared for each extensor digitorum. Afterwards, force was applied to each digit along the tendon axis from the loops inserted into the extensor tendons, to measure the extensor forces required to extend the MCP joints to 0˚ with a hand scale. The flexor tendons of the digits were dissected at zone III, and loop sutures were prepared individually for the tendons to enable independent flexion for each digit. The force required to fully flex the digits was measured with a hand scale. The extensor tendons were incised transversely and repaired at the mid-point in zone IV with three different suture techniques (double Kessler, double figure of eight, running interlocking horizontal mattress (RIHM)). The extenxor tendon lengths in zone IV were re-measured for all digits after suturing. The predetermined forces required for full flexion and extension of the digits were applied to the repaired digits. After force was applied 20 times to each tendon, the gap formation was checked. Totally 200 flexion and 200 extension movements were applied to each finger with the help of a hand-held scale. Formation of 2-mm gap was failure criteria. At the end of the movements the extent of the gaps was recorded. In the absence of insufficiency at the repair site, 50 additional flexion and extension movements with double the previously recorded forces were applied to the tendons. Results There was a significant shortening of the extensor tendons after repair independent from the used suture technique. No significant gap formation was detected in all three suture techniques. Conclusion All three suturing techniques are reliable for early active movements following the zone IV extensor tendon repairs. Therefore, surgeons can choose one of those three suture techniques to repair extensor tendon injuries in zone IV.

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