Gliding characteristics between flexor tendons and surrounding tissues in the carpal tunnel: A biomechanical cadaver study

Doesburg

et al. 2011

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To understand the potential mechanism for hand and wrist complaints in pipette users, whose motion is characterized by repetitive thumb motion in certain wrist positions, the peak (PGR) and mean (MGR) gliding resistance of the flexor pollicis longus (FPL) tendon were measured in nine human cadaver wrists. The PGR with the wrist in 308 ulnar deviation and in the neutral position were significantly lower than the PGR with the wrist in 608 flexion. The MGR with the wrist in 308 ulnar deviation was significantly lower than the MGR with the wrist in 608 flexion, 608 extension, or 208 radial deviation with 408 extension. Based on these data, we believe that a manual pipette designed to be used in neutral to ulnar deviated wrist position could have ergonomic advantages. Hand and wrist complaints, principally affecting the thumb, are common in individuals who use pipettes regularly in their work.1-6 Occurrence of such complaints was reported in up to 90% of individuals who continuously use pipettes for more than 60 min, 2 but little is known about the biomechanics associated with such complaints.One of the characteristics of the pipetting motion is repetitive thumb flexion in various positions of the wrist joint, especially wrist extension with radial deviation.1,3,5 Lee and Jiang 1 showed that the design of the pipette affects not only wrist position during usage, but also both the effectiveness and usability of pipetting. These data suggested to us that wrist position might affect thumb mechanics. To identify the difference of thumb mechanics while pipetting in various wrist positions, we focused on the gliding resistance of the main flexor of the thumb, the flexor pollicis longus (FPL) tendon, as pipetting requires repetitive forced flexion of the thumb with the wrist in various positions depending on the design of the specific pipette. Kutsumi et al.7 measured the gliding resistance of the FPL at the level of A1 to oblique pulley of the thumb, but this location is unaffected by wrist position. As no paper has reported the gliding resistance of the FPL tendon at the wrist level, we decided to measure the gliding resistance of the FPL tendon within the carpal tunnel. Our hypotheses were that the gliding characteristics of the FPL differed according to wrist position and that certain positions might minimize FPL friction during pipetting motions. To test these hypotheses we investigated FPL gliding resistance within the carpal tunnel in a human cadaver model. MATERIALS AND METHODS Specimen PreparationThis study was reviewed and deemed to be exempt by our Institutional Review Board. We used nine fresh frozen human cadaver upper extremities, obtained from five females and three males (mean age: 72.3 AE 13.5 years). Information regarding hand dominance was unavailable. One pair of specimens was bilateral. The specimens were amputated $15 cm proximal to the proximal wrist crease. Review of the medical records was performed on each cadaver donor to obtain demographic data and to be sure the individual did not have...

Section: Sample Size and Powermentioning

confidence: 85%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Measurement Of Gliding Resistancementioning

confidence: 99%

Section: Measurement Of Gliding Resistancementioning

confidence: 99%

See 3 more Smart Citations

The gliding characteristics of the flexor pollicis longus tendon in the carpal tunnel: Potential implications for manual pipette users

Morizaki

Doesburg

et al. 2011

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The effect of wrist position on the relative motion of tendon, nerve, and subsynovial connective tissue within the carpal tunnel in a human cadaver model

Yoshii

et al. 2008

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The purpose of this study was to measure the effect of wrist position on the relative motion of the middle finger flexor digitorum superficialis (FDS) tendon, subsynovial connective tissue (SSCT), median nerve, and flexor retinaculum during simulated active finger motion. The relative motion of each tissue was measured by fluoroscopy in 10 human cadavers. Measurements were obtained for wrist positions of neutral (0 degree extension), 30 and 60 degrees of flexion, and 30 and 60 degrees of extension. The shear strain index (SSI) was defined as the difference in motion between two tissues (tendon, SSCT, or nerve) divided by tendon excursion, expressed as a percentage. The motion of the tendon, SSCT, and nerve in the 60 degree flexed position was significantly less than the motion in all other wrist positions (p < 0.001). The SSI at 60 degrees of flexion for tendon–SSCT and tendon–nerve were significantly increased compared with all other positions (p < 0.001). Because the SSCT and tendon are physically connected, a decrease in SSCT motion relative to the tendon would increase the shear strain on the SSCT with tendon motion. Thus, this result suggests that the SSCT may be predisposed to shear injury from activity done in 60 degrees of wrist flexion.

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

Ettema

Berglund

et al. 2010

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ABSTRACT: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. © Carpal tunnel syndrome (CTS) in one of the most common compression neuropathies, with an estimated lifetime risk of 10% and a prevalence of about 3%.1-3 It is generally accepted that repetitive hand motion is a risk factor for CTS. [4][5][6][7] While the etiology of CTS is in most cases idiopathic, it is known that CTS is a result of increased pressure within the carpal tunnel, which is a confined anatomic space bounded by the carpal bones on the dorsal side, the trapezium on the radial side, the hook of the hamate on the ulnar side and the flexor retinaculum on the volar side. [8][9][10] However, while the effect of increase pressure on the median nerve has been well studied, the effect of pressure on tendon function has received little attention, even though tendons make up the majority of the cross section of the carpal tunnel contents. The purpose of this study was to investigate the effect of pressure changes on the gliding resistance of a representative tendon, the middle finger flexor digitorum superficialis (FDS), within the carpal tunnel in a human cadaver model. We hypothesized that the gliding resistance would increase with carpal tunnel pressure elevation. MATERIALS AND METHODSAfter IRB review and approval, eight human fresh frozen cadavers, amputated approximately 15 cm proximal to the wrist joint, were harvested and thawed at room temperature immediately prior to testing. The cadaver donors included five males and three females, with an average age of 76 years (range 40-91). There were five right and three left upper extremities. A medical record review was performed on each cadaver donor, to obtain demographic data and to be sure the individual did not have a recorded antemortem diagnosis of CTS. The FDS tendons of the second, third, and fourth digits were exposed proximal and distal to the flexor re...