Effect of laceration and trimming of a tendon on the coefficient of friction along the A2 pulley

Abstract

We carried out lacerations of 50%, followed by trimming, in ten turkey flexor tendons in vitro and measured the coefficient of friction at the tendon-pulley interface with loads of 200 g and 400 g and in 10 degrees , 30 degrees, 50 degrees and 70 degrees of flexion. Laceration increased the coefficient of friction from 0.12 for the intact tendon to 0.3 at both the test loads. Trimming the laceration reduced the coefficient of friction to 0.2. An exponential increase in the gliding resistance was found at 50 degrees and 70 degrees of flexion (p = 0.02 and p = 0.003, respectively) following trimming compared to that of the intact tendon. We concluded that trimming partially lacerated flexor tendons will reduce the gliding resistance at the tendon-pulley interface, but will lead to fragmentation and triggering of the tendon at higher degrees of flexion and loading. We recommend that higher degrees of flexion be avoided during early post-operative rehabilitation following trimming of a flexor tendon.

Kirschner Wire Fixation in Dorsally Displaced Distal Radius Fractures: A Biomechanical Evaluation

“…[22][23][24] Turkeys have powerful, relatively large lower limbs and have been widely used for biomechanical studies of tendon strength and gliding. 25,26 We are the first to use turkey long bones for fracture fixation testing but we believe the size, shape, bony properties, and our adequate sample size will produce meaningful results. The use of physiological bone is important as the cortex and medulla play vital roles in the creation and stability of the constructs.…”

Gliding Resistance and Modifications of Gliding Surface of Tendon

“…47 It is also clear from laboratory and clinical studies that both the gliding and healing of partially lacerated tendons (unless these are near complete) is better with trimming than with repair. 47,48 …”

Effect of triggering and entrapment on tendon gliding properties following digital flexor tendon laceration: in vitro study on turkey tendon

“…Based on a study by Hajipour (2010) using the Uchiyama technique, a power calculation was conducted using a friction coefficient (FC) increase of 42% between intact tendons and tendons with a 50% transverse palmar laceration (using a standard deviation of 0.28). To achieve a power of 80% and an alpha significance value of 0.05, seven tendon specimens would be required (Hajipour et al, 2010).…”

“…Based on a study by Hajipour (2010) using the Uchiyama technique, a power calculation was conducted using a friction coefficient (FC) increase of 42% between intact tendons and tendons with a 50% transverse palmar laceration (using a standard deviation of 0.28). To achieve a power of 80% and an alpha significance value of 0.05, seven tendon specimens would be required (Hajipour et al, 2010). However, Erhard (2002) demonstrated an increase of only 25% in the GR following a 50% transverse lateral laceration, which was significantly less than that recorded for 50% transverse palmar laceration (Erhard et al, 2002).…”

“…Palmar and lateral lacerations are most widely studied as these are the most common orientations of tendon injury. In vitro studies have reported conflicting results when assessing gliding properties (gliding resistance and friction coefficient), both between and within studies, and in particular for different depths (percentage) of injury (Erhard et al, 2002; Hajipour et al, 2010).…”