Measurement of the median nerve strain within the carpal tunnel using a capacitance-type strain sensor: A cadaver study


      • A new attempt to measure the median nerve strain within the carpal tunnel using an elastic sensor.
      • The median nerve strain within the carpal tunnel was higher than that proximal to the carpal tunnel.
      • Nerve excursion within the carpal tunnel was not different from that proximal to the carpal tunnel.
      • The median nerve strain and excursion were unaffected by carpal tunnel release.



      Direct and quantitative measurement of median nerve strain within the carpal tunnel has been difficult because of the technical limitations associated with conventional devices. We used capacitive sensors (C-stretch), which are thin and flexible, to measure the median nerve strain within the carpal tunnel.


      We used 12 fresh frozen upper extremity specimens. The transverse carpal ligament was left in situ, and we attached the sensor to the palmar surface of the median nerve to measure the nerve strain at 60 degrees of wrist extension. The sensor measured the median nerve strain at both the carpal tunnel site and the proximal to the carpal tunnel site before and after the carpal tunnel release. The amount of nerve excursion during wrist extension was also measured with the length change of the attached suture by a digital caliper.


      The mean median nerve strain within the carpal tunnel [8.07% (95 %CI:7.17–8.97)] was significantly higher than that proximal to the carpal tunnel [5.21% (95 %CI:4.46–5.97)] at the wrist extension. There was no significant difference of the mean nerve excursion within and proximal to the carpal tunnel. The mean nerve strain and excursion were unaffected by carpal tunnel release.


      These results indicated that wrist extension position might lead to increased strain on the median nerve within the carpal tunnel compared with at the proximal to the carpal tunnel. We believe that the current study might provide new information and help us understand the pathogenesis of carpal tunnel syndrome.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Clinical Biomechanics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Aoki M.
        • Takasaki H.
        • Muraki T.
        • Uchiyama E.
        • Murakami G.
        • Yamashita T.
        Strain on the ulnar nerve at the elbow and wrist during throwing motion.
        J. Bone Joint Surg. (Am. Vol.). 2005; 87: 2508-2514
        • Atroshi I.
        Prevalence of carpal tunnel syndrome in a general population.
        JAMA. 1999; 282: 153
        • Bay B.K.
        • Sharkey N.A.
        • Szabo R.M.
        Displacement and strain of the median nerve at the wrist.
        J. Hand Surg. 1997; 22: 621-627
        • Burke D.T.
        • Burke M.M.
        • Stewart G.W.
        • Cambre A.
        Splinting for carpal tunnel syndrome: in search of the optimal angle.
        Arch. Phys. Med. Rehabil. 1994; 75: 1241-1244
        • Byl C.
        • Puttlitz C.
        • Byl N.
        • Lotz J.
        • Topp K.
        Strain in the median and ulnar nerves during upper-extremity positioning.
        J. Hand Surg. 2002; 27: 1032-1040
        • Clark W.L.
        • Trumble T.E.
        • Swiontkowski M.F.
        • Tencer A.F.
        Nerve tension and blood flow in a rat model of immediate and delayed repairs.
        J. Hand Surg. 1992; 17: 677-687
        • Dilley A.
        • Lynn B.
        • Greening J.
        • DeLeon N.
        Quantitative in vivo studies of median nerve sliding in response to wrist, elbow, shoulder and neck movements.
        Clin. Biomech. (Bristol, Avon). 2003; 18: 899-907
        • Ellis R.
        • Blyth R.
        • Arnold N.
        • Miner-Williams W.
        Is there a relationship between impaired median nerve excursion and carpal tunnel syndrome? A systematic review.
        J. Hand Ther. 2017; 30: 3-12.doi
        • Evers S.
        • Thoreson A.R.
        • Smith J.
        • Zhao C.
        • Geske J.R.
        • Amadio P.C.
        Ultrasound-guided hydrodissection decreases gliding resistance of the median nerve within the carpal tunnel.
        Muscle Nerve. 2018; 57: 25-32
        • Festen-Schrier V.
        • Amadio P.C.
        The biomechanics of subsynovial connective tissue in health and its role in carpal tunnel syndrome.
        J. Electromyogr. Kinesiol. 2018; 38: 232-239
        • Gelberman R.H.
        • Hergenroeder P.T.
        • Hargens A.R.
        • Lundborg G.N.
        • Akeson W.H.
        The carpal tunnel syndrome. A study of carpal canal pressures.
        J. Bone Joint Surg. Am. 1981; 63: 380-383
        • Gelberman R.H.
        • Yamaguchi K.
        • Hollstien S.B.
        • Winn S.S.
        • Heidenreich Jr., F.P.
        • Bindra R.R.
        • Hsieh P.
        • Silva M.J.
        Changes in interstitial pressure and cross-sectional area of the cubital tunnel and of the ulnar nerve with flexion of the elbow. An experimental study in human cadavera.
        J. Bone Joint Surg. Am. 1998; 80: 492-501
        • Hicks D.
        • Toby E.B.
        Ulnar nerve strains at the elbow: the effect of in situ decompression and medial epicondylectomy.
        J. Hand Surg. 2002; 27: 1026-1031
        • Iba K.
        • Wada T.
        • Aoki M.
        • Tsuji H.
        • Oda T.
        • Yamashita T.
        Intraoperative measurement of pressure adjacent to the ulnar nerve in patients with cubital tunnel syndrome.
        J. Hand Surg. 2006; 31: 553-558
        • Koo T.K.
        • Li M.Y.
        A guideline of selecting and reporting Intraclass correlation coefficients for reliability research.
        J. Chiropractic Med. 2016; 15: 155-163
        • Kubo K.
        • Zhou B.
        • Cheng Y.S.
        • Yang T.H.
        • Qiang B.
        • An K.N.
        • Moran S.L.
        • Amadio P.C.
        • Zhang X.
        • Zhao C.
        Ultrasound elastography for carpal tunnel pressure measurement: a cadaveric validation study.
        J. Orthop. Res. 2018; 36: 477-483
        • Miyamoto H.
        • Aoki M.
        • Hidaka E.
        • Fujimiya M.
        • Uchiyama E.
        Measurement of strain and tensile force of the supraspinatus tendon under conditions that simulates low angle isometric elevation of the gleno-humeral joint: influence of adduction torque and joint positioning.
        Clin. Biomech. (Bristol, Avon). 2017; 50: 92-98
        • Mondelli M.
        • Giannini F.
        • Ballerini M.
        • Ginanneschi F.
        • Martorelli E.
        Incidence of ulnar neuropathy at the elbow in the province of Siena (Italy).
        J. Neurol. Sci. 2005; 234: 5-10
        • Nanno M.
        • Sawaizumi T.
        • Kodera N.
        • Tomori Y.
        • Takai S.
        Three-dimensional analysis of the attachment and path of the transverse carpal ligament.
        J. Nippon Med. Sch. 2015; 82: 130-135
        • Ochi K.
        • Horiuchi Y.
        • Nakamura T.
        • Sato K.
        • Arino H.
        • Koyanagi T.
        Ulnar nerve strain at the elbow in patients with cubital tunnel syndrome: effect of simple decompression.
        J. Hand Surg. Eur. 2013; 38: 474-480
        • Ogata K.
        • Naito M.
        Blood flow of peripheral nerve effects of dissection, stretching and compression.
        J. Hand Surg. (Edinburgh, Scotland). 1986; 11: 10-14
        • Pacek C.A.
        • Chakan M.
        • Goitz R.J.
        • Kaufmann R.A.
        • Li Z.M.
        Morphological analysis of the transverse carpal ligament.
        Hand (N Y). 2010; 5: 135-140
        • Rath T.
        • Millesi H.
        [The gliding tissue of the median nerve in the carpal tunnel].
        Handchir. Mikrochir. Plast. Chir. 1990; 22: 203-205.
        • Shirato R.
        • Aoki M.
        • Iba K.
        • Wada T.
        • Hidaka E.
        • Fujimiya M.
        • Yamashita T.
        Effect of wrist and finger flexion in relation to strain on the tendon origin of the extensor carpi radialis brevis: a cadaveric study simulating stretching exercises.
        Clin. Biomech. (Bristol, Avon). 2017; 49: 1-7
        • Szabo R.M.
        • Bay B.K.
        • Sharkey N.A.
        • Gaut C.
        Median Nerve Displacement through the Carpal Canal.
        Journal of Hand Surgery-American. 1994; 19a: 901-906.doi
        • Tanaka Y.
        • Aoki M.
        • Izumi T.
        • Fujimiya M.
        • Yamashita T.
        • Imai T.
        Effect of distal radius volar plate position on contact pressure between the flexor pollicis longus tendon and the distal plate edge.
        J. Hand Surg. 2011; 36: 1790-1797
        • Teramoto A.
        • Iba K.
        • Murahashi Y.
        • Shoji H.
        • Hirota K.
        • Kawai M.
        • Ikeda Y.
        • Imamura R.
        • Kamiya T.
        • Watanabe K.
        • Yamashita T.
        Quantitative evaluation of ankle instability using a capacitance-type strain sensor.
        Foot Ankle Int. 2021; 42: 1074-1080
        • Tuzuner S.
        • Inceoglu S.
        • Bilen F.E.
        Median nerve excursion in response to wrist movement after endoscopic and open carpal tunnel release.
        J. Hand Surg. Am. 2008; 33: 1063-1068.doi
        • Watanabe M.
        • Yamaga M.
        • Kato T.
        • Ide J.
        • Kitamura T.
        • Takagi K.
        The implication of repeated versus continuous strain on nerve function in a rat forelimb model.
        J. Hand Surg. 2001; 26: 663-669
        • Weiss N.D.
        • Gordon L.
        • Bloom T.
        • So Y.
        • Rempel D.M.
        Position of the wrist associated with the lowest carpal-tunnel pressure: implications for splint design.
        J. Bone Joint Surg. (Am. Vol.). 1995; 77: 1695-1699
        • Wright T.W.
        • Glowczewskie F.
        • Wheeler D.
        • Miller G.
        • Cowin D.
        Excursion and strain of the median nerve.
        J. Bone Joint Surg. (Am. Vol.). 1996; 78: 1897-1903
        • Yamaguchi T.
        • Osamura N.
        • Zhao C.
        • An K.N.
        • Amadio P.C.
        Relative longitudinal motion of the finger flexors, subsynovial connective tissue, and median nerve before and after carpal tunnel release in a human cadaver model.
        J. Hand Surg. 2008; 33: 888-892
        • Yamaji T.
        • Nakamoto H.
        • Ootaka H.
        • Hirata I.
        • Kobayashi F.
        Rapid prototyping human interfaces using stretchable strain sensor.
        J. Sensors. 2017; 2017 (Artn 989375810.1155/2017/9893758): 1-9
        • Yoshii Y.
        • Zhao C.
        • Zhao K.D.
        • Zobitz M.E.
        • An K.N.
        • Amadio P.C.
        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.
        J. Orthop. Res. 2008; 26: 1153-1158