Mean Gliding Resistance Research Articles

Gliding Resistance After Epitendinous-First Repair of Flexor Digitorum Profundus in Zone II

The importance of flexor tendon repair with both core and epitendinous suture placement has been well established. The objective of this study was to determine whether suture placement order affects gliding resistance and bunching in flexor digitorum profundus tendons in a human exvivo model. The flexor digitorum profundus tendons of the index, middle, ring, and little fingers of paired cadaver forearms were tested intact for excursion and mean gliding resistance in flexion and extension across the A2 pulley. Tendons were subsequently transected and repaired with either an epitendinous-first (n= 12) or a control (n= 12) repair. Gliding resistance of pair-matched tendons were analyzed at cycle 1 and during the steady state of tendon motion. The tendon repair breaking strength was also measured. The mean steady state gliding resistance was less for the epitendinous-first repair than for the control repair in flexion (0.61 N vs 0.72 N) and significantly less in extension (0.68 N vs 0.85 N). Similar results were seen for cycle 1. None of the repairs demonstrated gap formation; however, control repairs exhibited increased bunching. Load to failure was similar for both groups. The order of suture placement for flexor tendon repair is important. Epitendinous-first repair significantly decreased mean gliding resistance, allowed for easier placement of core sutures, and resulted in decreased bunching. Epitendinous-first flexor tendon repairs may contribute to improved clinical outcomes compared with control repairs by decreasing gliding resistance and bunching.

Effects of different temperatures, velocities and loads on the gliding resistance of flexor digitorum profundus tendons in a human cadaver model

The purpose of this study was to investigate the effects of temperature, velocity and load on the gliding resistance (GR) of flexor digitorum profundus (FDP) tendons in a human cadaver model. A total of 40 FDP tendons from the index through small digits of ten human cadavers were tested to assess the effect of temperature (4, 23 or 36°C), velocity (2, 4, 6, 8, 10 or 12 mm/s) and load (250, 500, 750, 1000, 1250 and 1500 g) on GR. The mean GR at 4 °C was significantly higher than the mean GR at 36 °C ( p<0.0066). There was no significant difference in the mean GR of the tested velocities. The mean GR was proportional to load, with each successive load having significantly higher GR than the loads before it (all p<0.001). There was no significant difference in the mean GR by digit. In this in vitro model, we have demonstrated that tendon gliding resistance is proportional to load, independent of velocity and somewhat affected by temperature. We conclude that it is important to specify these conditions when reporting gliding resistance, especially load and temperature.

Human synoviocyte lubricin and bovine synovial fluid lubricin equally improve gliding resistance in a canine model in vitro

The lubricating ability of human synoviocyte lubricin and bovine lubricin purified from synovial fluid was investigated and compared using a canine in vitro tendon model. Our null hypothesis was that these two forms of lubricin would have equal lubricating ability. Forty two canine hind-limbs were used. The peroneus longus (PL) tendons were harvested, along with the proximal phalanx and flexor digitorum profundus of the second or fifth digit with its proximal fibro-osseous pulley. Forty PL tendons were randomly assigned to one of four treatment groups. After gliding resistance testing, two intact PL tendons and two tendons in each group were randomly selected for surface observation with scanning electron microscopy (SEM). The variance of the PL saline group mean gliding resistance was significantly different from other groups. There was a significant treatment-cycle interaction effect on the mean gliding resistance. On SEM, the surface of the saline treated PL tendons appeared rough, whereas the other tendon surfaces appeared smooth. Human synoviocyte lubricin functioned as well as bovine synovial fluid lubricin to reduce friction of canine PL tendons in vitro. This data suggest that treatment using the two forms of lubricin are mechanically similar.

Gliding resistance of flexor tendon associated with carpal tunnel pressure: a biomechanical cadaver study.

The purpose of this study was to investigate the effect of carpal tunnel pressure on the gliding characteristics of flexor tendons within the carpal tunnel. Eight fresh human cadaver wrists and hands were used. A balloon was inserted into the carpal tunnel to elevate the pressure. The mean gliding resistance of the middle finger flexor digitorum superficialis tendon was measured with the following six conditions: (1) as a baseline, before balloon insertion; (2) balloon with 0 mmHg pressure; (3) 30 mmHg; (4) 60 mmHg; (5) 90 mmHg; (6) 120 mmHg. The gliding resistance of flexor tendon gradually increased as the carpal tunnel pressure was elevated. At pressures above 60 mmHg, the increase in gliding resistance became significant compared to the baseline condition. This study helps us to understand the relationship between carpal tunnel pressure, which is elevated in the patient with carpal tunnel syndrome (CTS) and tendon gliding resistance, which is a component of the work of flexion. These findings suggest that patients with CTS may have to expend more energy to accomplish specific motions, which may in turn affect symptoms of hand pain, weakness and fatigue, seen commonly in such patients.

Gliding Resistance of the Posterior Tibial Tendon

Abnormal gliding of the posterior tibial tendon may lead to mechanical trauma, degeneration, and eventually posterior tibial tendon dysfunction. Our study analyzed the gliding resistance of the posterior tibial tendon in intact feet and in feet with simulated flatfoot deformity. An experimental system was developed that allowed direct measurement of gliding resistance at the tendon-sheath interface. Seven normal fresh-frozen cadaver foot specimens were studied, and gliding resistance between the posterior tibial tendon and sheath was measured. The effects of ankle and hindfoot position and the effect of flatfoot deformity on gliding resistance were analyzed. Gliding resistance was measured for 4.9 N applied load to the tendon. Mean gliding resistance for the neutral position was 77 +/- 13.1 (x10(-2) N). Compared to neutral position, dorsiflexion increased gliding resistance and averaged 130 +/- 38.9 (x10(-2) N), and plantarflexion decreased gliding resistance and averaged 35 +/- 12.6 (x10(-2) N). Flatfoot deformity increased gliding resistance compared to normal feet, averaging 104 +/- 17.0 (x10(-2) N) for neutral, 205 +/- 55.0 (x10(-2) N) for dorsiflexion, and 58 +/- 21.3 (x10(-2) N) for plantarflexion. The findings indicate that patients with a preexisting flatfoot deformity may be predisposed to develop posterior tibial tendon dysfunction because of increased gliding resistance and trauma to the tendon surface.

Finkelstein’s test: A biomechanical analysis

Finkelstein's test is the classic diagnostic test for de Quervain's disease. Finkelstein hypothesized that the entry of the muscle bellies of the extensor pollicis brevis (EPB) and abductor pollicis longus (APL) tendons into the first extensor compartment was responsible for the findings observed in his now eponymous test. We agree with Finkelstein's hypothesis and further hypothesize that this position would induce measurable bulk (muscle mass within the retinaculum) and tethering (stretching of synovial tissue) effects within the compartment. To test this latter hypothesis we measured the excursion and gliding resistance of the EPB and APL tendons within the first compartment. Fifteen fresh-frozen cadavers were used. Gliding resistance and excursion were measured in 4 different wrist positions, including the wrist position of Finkelstein's test (30 degrees ulnar deviation). The bulk and tethering effect was calculated based on the mean gliding resistance over the tendon proximal/distal excursion cycle and the gliding resistance at the terminal distal excursion. The EPB tendon excursion was significantly more distal in 30 degrees ulnar deviation than in 60 degrees extension. Additionally the bulk and tethering resistance was significantly greater in 30 degrees ulnar deviation compared with 60 degrees extension. For the APL tendon there was no significant difference in either the tendon excursion or the bulk and tethering resistance between 30 degrees ulnar deviation and 60 degrees extension. We showed that in the position of Finkelstein's test the EPB tendon is significantly more distal and has significantly greater bulk and tethering effect compared with the other EPB positions. This is not the case for the APL tendon in the position of Finkelstein's test. These results suggest that an abnormal Finkelstein's test reflects differences of the EPB more than it does the APL.

Measurement of gliding resistance of the extensor pollicis longus and extensor digitorum communis II tendons within the extensor retinaculum

Purpose The etiology of spontaneous extensor pollicis longus (EPL) tendon rupture is still largely unknown. It is possible that friction within the sheath may play a role. The purposes of this study were to compare gliding resistance of the EPL tendon with that of the extensor digitorum communis tendon of the index finger (EDC II) and to find the wrist position that gives the EPL tendon the lowest gliding resistance. Methods Fifteen fresh-frozen cadavers were used. Gliding resistance was measured directly in 7 different wrist positions. Results The mean gliding resistance of the EPL tendon was 0.16 ± 0.08 N and that of the EDC II tendon was 0.11 ± 0.06 N. This difference was significant. There was also a significant effect on gliding resistance due to wrist position. For the EPL tendon, the gliding resistance was significantly greater in 60° wrist flexion compared with all other wrist positions tested. Additionally the gliding resistance of the EPL in 30° flexion, 60° extension, and 15° radial deviation was significantly higher than wrist positions of 30° extension, neutral, and 30° ulnar deviation. Conclusions Positioning the wrist close to neutral flexion/extension and in some ulnar deviation minimizes the friction within the EPL sheath. Such positions may be advantageous for splinting patients at risk for EPL rupture.