scholarly journals Biomechanical interaction between the transverse carpal ligament and the thenar muscles

2013 ◽  
Vol 114 (2) ◽  
pp. 225-229 ◽  
Author(s):  
Zhilei Liu Shen ◽  
Zong-Ming Li

The transverse carpal ligament (TCL) serves as the origin of the thenar muscles and is integral to thenar muscle contraction anatomically and biomechanically. TCL hypertrophy has been observed in patients with carpal tunnel syndrome and is potentially caused by repetitive hand use. The purpose of this study was to investigate the biomechanical interaction between the TCL and the thenar muscles. Specifically, the morphological changes of the carpal arch, formed by the TCL, in response to thenar muscle contractions were examined during isometric tip pinch between the thumb and index finger. Ultrasound videos of the carpal tunnel were recorded from 13 healthy subjects and were synchronized with the forces measured by a pinch dynamometer. The thenar muscles' ulnar point, trapezium, and hamate were tracked by a pattern-matching program. The pinch force significantly affected the carpal arch height, width, and area ( P < 0.005). As the pinch force increased from 0 to 100% maximum voluntary contraction force, the carpal arch height increased from 1.8 ± 1.0 to 2.3 ± 1.3 mm, the carpal arch width decreased from 23.9 ± 2.4 to 23.1 ± 2.4 mm, and the carpal arch area increased from 22.2 ± 13.6 to 27.3 ± 16.3 mm2. The TCL was pulled volarly during thenar muscle contractions, providing evidence for the biomechanical interaction between the ligament and muscles. Repetitive biomechanical stimulation on the TCL from thenar muscle contractions could lead to tissue remodeling and then TCL hypertrophy. This study sheds light on the potential cause of TCL hypertrophy, which may be an etiological factor for carpal tunnel syndrome.

Hand Surgery ◽  
2013 ◽  
Vol 18 (03) ◽  
pp. 411-412
Author(s):  
Takashi Shimoe ◽  
Yasunori Taniguchi ◽  
Munehito Yoshida

Carpal tunnel syndrome is a common condition; however, it has not been previously reported in patients with hemihypertrophy. A 67-year-old woman with left-sided hemihypertrophy presented with carpal tunnel syndrome of the left hand. Magnetic resonance imaging showed enlargement of the median nerve proximal to the transverse carpal ligament. Carpal tunnel decompression was performed, and pain was immediately relieved by decompression of the carpal tunnel. At the six-month follow-up examination, the patient experienced relief from numbness and improvement in thenar muscle atrophy was noted.


Author(s):  
Trevor Simcox ◽  
Lauren Seo ◽  
Kevin Dunham ◽  
Shengnan Huang ◽  
Catherine Petchprapa ◽  
...  

Abstract Background The etiology of carpal tunnel syndrome (CTS) is multifactorial. Static mechanical characteristics of CTS have been described, but dynamic (muscular) parameters remain obscure. We believe that musculature overlying the transverse carpal ligament may have an effect on carpal tunnel pressure and may explain the prevalence of CTS in manual workers. Questions/Purposes To utilize magnetic resonance imaging (MRI) imaging to estimate the amount of muscle crossing the area of the carpal tunnel and to compare these MRI measurements in patients with and without documented CTS. Methods A case–control study of wrist MRI scans between January 1, 2018, and December 1, 2019, was performed. Patients with a diagnosis of CTS were matched by age and gender with controls without a diagnosis of CTS. Axial MRI cuts at the level of the hook of the hamate were used to measure the thenar and hypothenar muscle depth overlying the carpal tunnel. Muscle depth was quantified in millimeters at three points: midcapitate, capitate–hamate border, capitate–trapezoid border. Average depth was calculated by dividing the cross-sectional area (CSA) by the transverse carpal ligament width. Statistical analysis included Student's t-test, chi-square test, and Pearson's correlation coefficient calculation. Results A total of 21 cases and 21 controls met the inclusion criteria for the study. There were no significant differences in demographics between case and control groups. The location and depth of the musculature crossing the carpal tunnel were highly variable in all areas evaluated. A significantly positive correlation was found between proximal median nerve CSA and muscle depth in the capitate–hamate area (correlation coefficient = 0.375; p = 0.014). CSA was not significantly associated with chart documented CTS. Conclusions We found large variability in our measurements. This likely reflects true anatomical variation. The significance of our findings depends on the location of the muscles and the line of pull and their effect on the mechanics of the transverse carpal ligament. Future research will focus on refining measurement methodology and understanding the mechanical effect of the muscular structure and insertions on carpal tunnel pressure. Level of Evidence This is a Level 3, case–control study.


2021 ◽  
Vol 67 (4) ◽  
pp. 518-525
Author(s):  
Zuhal Özişler ◽  
Müfit Akyüz

Objectives: This study aims to evaluate the predictors of standard nerve conduction study (NCS) parameters in determining the presence of axonal loss by means of spontaneous activity in patients with mild and moderate carpal tunnel syndrome (CTS). Patients and methods: Between May 2015 and April 2018, a total of 118 patients (11 males, 107 females; mean age: 52.3±10.6 years; range, 27 to 79 years) who underwent electrophysiological studies and were diagnosed with CTS were included. Demographic data of the patients including age, sex, and symptom duration were recorded. Electrodiagnostic studies were performed in all patients. All the needle electromyography (EMG) findings were recorded, but only the presence or absence of spontaneous EMG activities was used as the indicator of axonal injury. Results: In 37 (31.4%) of the patients, spontaneous activity was detected at the thenar muscle needle EMG. No spontaneous activity was observed in any of 43 (36.4%) patients with normal distal motor latency (DML). There were significant differences in DMLs, compound muscle action potential (CMAP) amplitudes, sensory nerve action potentials amplitudes, and sensory nerve conduction velocities between the groups with and without spontaneous activity (p<0.05). The multiple logistic regression analysis revealed that DML was a significant independent risk variable in determining presence of spontaneous activity. The most optimal cut-off value for median DML was calculated as 4.9 ms. If the median DML was >4.9 ms, the relative risk of finding spontaneous activity on thenar muscle needle EMG was 13.5 (95% CI: 3.6-51.2). Conclusion: Distal motor latency is the main parameter for predicting the presence of spontaneous activity in mild and moderate CTS patients with normal CMAP. Performing needle EMG of the thenar muscle in CTS patients with a DML of >4.9 ms may be beneficial to detect axonal degeneration in early stages.


2008 ◽  
Vol 26 (6) ◽  
pp. 551-557 ◽  
Author(s):  
Wen-Dien Chang ◽  
Jih-Huah Wu ◽  
Joe-Air Jiang ◽  
Chun-Yu Yeh ◽  
Chien-Tsung Tsai

1987 ◽  
Vol 12 (3) ◽  
pp. 366-374
Author(s):  
M. NAITO ◽  
K. OGATA ◽  
T. GOYA

A prospective study was performed on 62 hands in 45 consecutive patients on chrome dialysis carpal tunnel syndrome developed within an average of 116 months after formation of the arterio-venous fistula. We measured the intra-carpal canal pressure by the wick catheter technique and performed neurography. At operation, a markedly thickened transverse carpal ligament was usually found. A pneumatic tourniquet was applied in all except three cases, whose functioning fistulae were made of implants, but no complications such as obturation of the fistulae occurred. Thirty-three (76.7%) of 43 cases had good results. Full recovery of sensibility was obtained in all hands in which symptoms had been present for less than two years. There was no benefit from operation in two patients (4.7%), both of whom had symptoms for more than two years.


Author(s):  
Suk H. Yu ◽  
Tracy A. Mondello ◽  
Zong-Ming Li

Carpal tunnel syndrome is conventionally treated by open and endoscopic release surgeries in which transecting the transverse carpal ligament (TCL) relieves mechanical insults around the median nerve. The TCL release surgeries yield an increase in the tunnel cross-sectional area particularly within the volar aspect of the tunnel, the arch area, where the median nerve is located. As a result of increased arch area, post-operative follow-up studies using MRI confirmed a significant volar migration of the median nerve [1]. However, transecting the TCL compromises critical biomechanical roles of the carpal tunnel [2], and therefore, it is imperative to investigate an alternative method for treating carpal tunnel syndrome patients while preserving the TCL. Li et al. suggested that increasing the TCL length and narrowing the carpal arch width (CAW) as potential alternatives for increasing the arch area [3]. However, the data from their application of palmarly directed forces to the TCL from inside of the tunnel showed that the TCL length remained relatively constant while the carpal bones were mobilized to increase the arch area [3]. The purpose of this study was to investigate the relationship between CAW narrowing and the TCL-formed arch area by experimental and geometrical modeling.


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