Carpal arch and median nerve changes during radioulnar wrist compression in carpal tunnel syndrome patients

Abstract

The purpose of this study was to investigate the morphological changes of the carpal arch and median nerve during the application of radiounlarly directed compressive force across the wrist in patients with carpal tunnel syndrome. Radioulnar compressive forces of 10 N and 20 N were applied at the distal level of the carpal tunnel in 10 female patients diagnosed with carpal tunnel syndrome. Immediately prior to force application and after 3 minutes of application, ultrasound images of the distal carpal tunnel were obtained. It was found that applying force across the wrist decreased the carpal arch width (p < 0.001) and resulted in increased carpal arch height (p < 0.01), increased carpal arch curvature (p < 0.001), and increased radial distribution of the carpal arch area (p < 0.05). It was also shown that wrist compression reduced the flattening of the median nerve, as indicated by changes in the nerve’s circularity and flattening ratio (p < 0.001). Statement of clinical significance This study demonstrated that the carpal arch can be non-invasively augmented by applying compressive force across the wrist, and that this strategy may decompress the median nerve providing symptom relief to patients with carpal tunnel syndrome.

Subject-specific finite element analysis of the carpal tunnel cross-sectional to examine tunnel area changes in response to carpal arch loading

“…CAW values during widening always remained lower than the length of the TCL itself, indicating the TCL did not assume a tensioned state. Narrowing of CAW has been shown to increase the volar area of the carpal tunnel in previous biomechanical studies (Li et al, 2013; Marquardt et al, 2016; Marquardt et al, 2015). The reduction in CAW was maximized in radial volar direction (at 138° from 25.1 to 24.4 mm).…”

“…Similarly, another in vivo study evaluating the pinching of the index finger against thumb reported a decrease of 0.8 mm in CAW and an increase of 5.1 mm 2 in volar area (Shen and Li, 2013). Several other studies also have shown that an increase in volar area results from the narrowing of the CAW (Li et al, 2013; Li et al, 2011; Li et al, 2009; Marquardt et al, 2016; Marquardt et al, 2015). The current FE model demonstrated that changes in the dorsal area were smaller than those of volar area, indicating that during narrowing the formation of the ligament arch contributes to an increase in the overall area of the tunnel.…”

“…Decreasing the CAW at the distal row was demonstrated to increase the volar arch area of the carpal tunnel (Fig. 1), i.e., the area formed by the TCL divided by a reference line from the ridge of the trapezium and hook of the hamate (Li et al, 2013; Li et al, 2011; Li et al, 2009; Marquardt et al, 2016; Marquardt et al, 2015). However, previous studies were limited to the examination of effects of CAW on volar area without the inclusion of the dorsal arch area formed by carpal bones.…”

“…This CAW change is attributable to the mobility of carpal bones which is guided by bone/cartilage configuration and inter-carpal ligaments (Gabra et al, 2012; Xiu et al, 2010). Attempts to widen (Sucher et al, 2005) or narrow (Li et al, 2013; Marquardt et al, 2016; Marquardt et al, 2015) the CAW have been made to alter the carpal tunnel morphological structure as a means to increase the carpal tunnel cross-sectional area (CSA) for median nerve decompression. Widening the CAW can be limited due to the mechanical constraint imposed by the thick band of the transverse carpal ligament.…”

“…Widening the CAW can be limited due to the mechanical constraint imposed by the thick band of the transverse carpal ligament. Narrowing of the CAW has been examined by applying forces to the carpal bones in cadaveric hands (Gabra and Li, 2016) and to the radio-ulnar aspects of the wrist in human subjects (Marquardt et al, 2016; Marquardt et al, 2015). Decreasing the CAW at the distal row was demonstrated to increase the volar arch area of the carpal tunnel (Fig.…”