Effects of Carpal Tunnel Release on Biomechanical Behavior of Flexor Tendons - A Clinical Study

Abstract

Carpal tunnel syndrome (CTS) is a common disorder of the hand in clinics and is caused by pressure on the median nerve The main symptoms include numbness tingling and even loss of sensation in the area of fingers that receive sensory and motor function from the median nerve and this may then further influence hand functions in daily life For severe CTS patients carpal tunnel release (CTR) surgery is recommended to decompress the median nerve by incising the transverse carpal ligament (TCL) in the carpal tunnel However it is observed that a noticeable percentage of CTR patients develop symptoms of trigger finger (TF) after the release surgery Among the possible risk factors that have been investigated many studies have attributed this phenomenon to the lack of the support of the TCL in the wrist after CTR Because the restraining effect of the TCL is lost the “bowstring” effect of the flexor tendon might occur and further result in biomechanical changes in the hand In order to provide more information on the possible pathophysiologic mechanism in this context ultrasonography and a custom-designed dynamometer were used to measure the change in biomechanical behavior of flexor tendon post CTR surgery in this study Fourteen subjects with CTS who underwent ultrasonographically guided percutaneous CTR surgery were recruited in this study The long finger of the symptomatic hand was the examined finger The first part of the study was to investigate the mechanical properties of flexor tendon; the second was to measure the volar-dorsal migration in the carpal tunnel and the change in the entrance angle at the MCP joint The results with regard to mechanical properties demonstrated that the FDS tendon force FDS tendon stiffness at linear region and FDS tendon contribution all increased significantly post release Because the symptoms of CTS were relieved after the release surgery these results might indicate better force performance better efficiency of force performance and better recovery respectively In the second part of the study greater distance between the FDS tendon and capitate bone and greater angle between the flexor tendon and metacarpal bone were found post release Furthermore a strong positive correlation was also found between volar-dorsal migration and the change in the entrance angle providing evidence of a possible mechanism that predisposes CTR patients to TF This study provides more information regarding the changes in biomechanical behavior of flexor tendons after the release surgery and evidence of a possible pathophysiologic mechanism that would predispose CTR patients to subsequently developing TF

Date of Award	2017 Aug 31
Original language	English
Supervisor	Fong-chin Su (Supervisor)