The Weakest Point of “The Shepherd’s Crook” Technique: Suture Tension
We read the article “The Pull-out K-Wire Anchorage: The ‘Shepherd’s Crook’ Technique” by De Spirito et al with great interest. We want to express our opinions about this subject.
Pull out technique for tendon injuries has been used for a long time. A bone tunnel created at distal phalanx carries the bending moment to the palmar face of finger. Suture passing through the distal phalanx is secure to the button placed on the pulpa of the effected finger. Main disadvantage of this technique is worries about skin necrosis. A sponge between skin and button and elaborate care may prevent this complication.
The rotation effect of the repaired tendon can be defined as the bending effect. The force in the plane creates a moment effect on a selected rotation axis. The magnitude of the momentum depends on the strength of the force as well as the distance between the force and the axis. This distance between the force and the axis is called the moment arm. The magnitude of the momentum equals the force and momentum multiplication. If the moment arm lengthens, the bending strength also increases. We think that this technique lengthens the moment arm and this new situation results with loss of suture tension. We are looking forward to reading new study about authors’ surgical results.
Zhang et al1 described a technique about this issue and this study were published at Journal of Hand Surgery American at 2012 with the name of “Pull-out Wire Fixation for Acute Mallet Finger Fractures With K-Wire Stabilization of the Distal Interphalangeal Joint.” Authors also have cited this study at their work.