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The purpose of this study was to compare the stiffness of the transverse carpal ligament (TCL) between healthy volunteers and carpal tunnel syndrome (CTS) patients using sonoelastography. We studied 17 healthy volunteers (four men, 13 women; range 37–84 years) and 18 hands of 13 patients with CTS (three men, ten women; range 41–79 years). Thickness and elasticity of the TCL were evaluated by sonoelastography. Elasticity was estimated by strain ratio of an acoustic coupler, which has a standardized elasticity as a reference medium, to the TCL (AC/T strain ratio). The AC/T strain ratios of the healthy volunteers and the CTS patients were 6.0 and 8.1, respectively (p = 0.030). The AC/T strain ratio showed a positive correlation with the duration of symptoms in the CTS patients (p = 0.035, r = 0.50). We concluded that increased stiffness of the TCL could be one of the causes for CTS.

The purposes of this study were to investigate the mechanical properties of the carpal tunnel and to examine carpal tunnel compliance as it related to gender difference. Twelve male and twelve female subjects without any neuromusculoskeletal disorders in the upper extremities participated in the study. Indentation testing was manually performed on the wrist volar to the transverse carpal ligament. Effective compliance was defined as the slope of the regression analyses of indentation force and displacement data. In the tested indentation force range (2.45–19.60 N), the displacement of females was 1.38 ± 0.25 mm, significantly smaller than that of the males, 1.82 ± 0.30 mm (p < 0.001). Regression analyses in the force range showed that the effective compliance for females, 0.075 ± 0.012 mm/N, was 26.3% lower than that for males, 0.101 ± 0.018 mm/N (p < 0.005). It was concluded that females have less compliant carpal tunnel than males. The gender difference in carpal tunnel mechanics may predispose females to detrimental compression of the median nerve and carpal tunnel syndrome.

The purpose of this study was to investigate the morphological and mechanical properties of the transverse carpal ligament (TCL) in patients with carpal tunnel syndrome (CTS). Thickness and stiffness of the TCL in eight female CTS patients and eight female control subjects were examined using ultrasound imaging modalities. CTS patients had a 30.9% thicker TCL than control subjects. There was no overall difference in TCL stiffness between the two groups, but the radial TCL region was significantly stiffer than the ulnar region within the CTS group and such a regional difference was not found for the controls. The increased thickness and localized stiffness of the TCL for CTS patients may contribute to CTS symptoms due to reduction in carpal tunnel space and compliance. Advancements in ultrasound technology provide a means of understanding CTS mechanisms and quantifying the morphological and mechanical properties of the TCL in vivo.

Technical steps to avoid incomplete proximal release of the carpal tunnel are described. Local anaesthesia is infiltrated as a subcutaneous bleb over the distal wrist crease and extending 2–3 cm over the forearm fascia. Tumescence of local anaesthesia into the subcutaneous plane helps create a pocket between the forearm fascia and subcutaneous tissues. Intraoperatively a subcutaneous pocket is made above the transverse carpal ligament and antebrachial fascia with blunt dissection. A retractor is placed under the pocket, which facilitates optimal visualization to allow reliable complete proximal release of compression.The authors have found that this technique is reproducible and reliable across their collective experience.

Background: Closed mini-wrist transverse incision for carpal tunnel release has been reported in decreasing surgical scar problems, but there were few cadaveric studies that proved the effectiveness and safety in this technique without protective instrument to the median nerve. Hydro-dissection was previously showed to separate median nerve and deep structures during percutaneous ultrasound guided transverse carpal ligament release. This cadaveric study aims to demonstrated effectiveness and safety of closed transverse carpal ligament (TCL) release though the mini-transverse incision at distal wrist crease combined with hydrodissection technique. Neither special instrument nor retractor was used to protect neurovascular structures.

Methods: Twelve fresh frozen cadaveric wrists were included in this study. Completeness of TCL release and injury to the adjacent neurovascular structures were assessed by direct visualization. Thickness of TCL, TCL length and distance from incision to adjacent neurovascular structures were also recorded.

Results: Complete release of TCL was demonstrated in all 12 (100%) wrists underwent the mini-transverse incision TCL release at distal wrist crease and hydro-dissection technique. No injury to the adjacent neurovascular structures was found in all 12 wrists. Mean of thickness of TCL and TCL length were 3 mm and 28.7 mm, respectively. The ulnar artery was the nearest structure to the incision (mean = 3.7 mm).

Conclusions: The closed mini-transverse incision TCL release at distal wrist crease with hydro-dissection technique demonstrated completeness of TCL division and safety to the neurovascular structures without protecting retractor or special instrument.

Background: The anatomical structures in relation to the carpal tunnel release are the palmaris brevis muscle (PBM), transverse carpal ligament (TCL), and the recurrent motor branch of the median nerve (RMBMN). Our aim is to describe the gross morphology in the Korean population of the PBM, TCL, and RMBMN specifically looking for anomalies, and to determine the muscles encountered during a standard carpal tunnel release.

Material and Methods: A total of 30 cadaveric hands were dissected. A longitudinal line drawn from the third web space to the midpoint of the distal wrist crease served as the reference line (RL). The PBM and TCL were classified according to its shape and location. The length, width, and thickness of the TCL were measured. The ratio of the lengths of PBM and TCL to RL was calculated. The course of the RMBMN was dissected specifically looking for anomalies. We also looked at the muscle fibers encountered during a standard carpal tunnel release to identify the muscle.

Results: PBM was classified into three different types based on the shape. The average thickness of the PBM and TCL were 0.89 ± 0.16 mm and 1.43 ± 0.40 mm, respectively. The distal border of the TCL was thicker than the proximal border. The average ratio of the length of the PBM to the RL was 25.65 ± 8.62% and TCL to the RL was 24.00 ± 3.37%. The distribution of the RMBMN was classified into three different types. A few accessory branches of the RMBMN were also noted. And 36 muscle fibers were noted within the TCL in line with the RL.

Conclusion: We clarified findings and added quantitative information about the anatomical structures surrounding carpal tunnel. A thorough knowledge of the anatomy and anomalies around the carpal tunnel is helpful for surgeons to ensure optimal surgical results.

Background: Dynamic forces acting on the transverse carpal ligament (TCL) may influence the mechanics of the carpal tunnel (CT), thus affecting the occurrence of CT syndrome (CTS). Previous studies demonstrated an association between muscle overlying the CT and the diagnosis of CTS. Understanding the location of insertion/origin of the thenar musculature will allow mechanical analysis of the forces applied to the TCL during performance of individual tasks. Our purpose was to determine the location of muscle overlying the CT on magnetic resonance imaging (MRI) in CTS and controls.

Methods: Case-control study of 21 normal adult wrist MRI scans. MRI measurements were performed on an axial cut at the level of the hook-of-hamate. Median nerve cross-sectional area (CSA), median nerve shape and increased signal intensity within the CT were associated with CTS. The amount and length of muscle crossing the midline and the CT on the same cut was measured and the association with the occurrence of CTS was analysed.

Results: We found an inverse relationship between the amount of muscle crossing the midline and the size of the CT, and a direct relationship with occurrence of CTS p less than 0.01, but no differences regarding length of muscle crossing the midline.

Conclusions: This study supports an association between the thenar musculature location relative to the CT and the predictors of CTS on MRI. Since the location of muscle origin/insertion is variable, their effect may differ accordingly, therefore, further study is needed to describe the exact location of origin/insertion and its differential dynamic or static effect on the pathogenesis of CTS.

Level of Evidence: Level IV (Diagnostic)