Anatomic Relationship between the Hook of the Hamate and the Distal Transverse Carpal Ligament: Implications for Ultrasound Guided Carpal Tunnel Release

ABSTRACTObjectiveDuring ultrasound guided carpal tunnel release (USCTR), osseous landmarks may supplement direct visualization of the distal transverse carpal ligament (dTCL) to ensure a complete release. The purpose of this study was to determine the relationship between the apex of the hook of the hamate (aHH) and the dTCL within the transverse safe zone (TSZ) of the carpal tunnel.DesignTwenty unembalmed cadaveric specimens were dissected to determine the aHH-dTCL distance and the aHH-SPA distance (the distance between the aHH and the superficial palmar arch) at the ulnar and radial limits of the TSZ (the distance between the hook of the hamate or ulnar artery to the median nerve).ResultsThe aHH-dTCL distance averaged 11-12 mm across the TSZ (maximum 18.2 mm), whereas the aHH-SPA distance was significantly greater on the radial side of the TSZ compared to the ulnar side (22.6 ± 3.6 mm versus 14.0 ± 4.0 mm).ConclusionsThe dTCL lies approximately 11-12 mm distal to the aHH across the TSZ, with an upper limit of 18.2 mm. Along with direct sonographic visualization of the dTCL, the aHH can be used with other osseous landmarks to estimate the position of the dTCL during USCTR. Objective During ultrasound guided carpal tunnel release (USCTR), osseous landmarks may supplement direct visualization of the distal transverse carpal ligament (dTCL) to ensure a complete release. The purpose of this study was to determine the relationship between the apex of the hook of the hamate (aHH) and the dTCL within the transverse safe zone (TSZ) of the carpal tunnel. Design Twenty unembalmed cadaveric specimens were dissected to determine the aHH-dTCL distance and the aHH-SPA distance (the distance between the aHH and the superficial palmar arch) at the ulnar and radial limits of the TSZ (the distance between the hook of the hamate or ulnar artery to the median nerve). Results The aHH-dTCL distance averaged 11-12 mm across the TSZ (maximum 18.2 mm), whereas the aHH-SPA distance was significantly greater on the radial side of the TSZ compared to the ulnar side (22.6 ± 3.6 mm versus 14.0 ± 4.0 mm). Conclusions The dTCL lies approximately 11-12 mm distal to the aHH across the TSZ, with an upper limit of 18.2 mm. Along with direct sonographic visualization of the dTCL, the aHH can be used with other osseous landmarks to estimate the position of the dTCL during USCTR. Please send correspondence to: Jay Smith, M.D. Department of PM&R, W14 Mayo Building, 200 1st ST, SW, Rochester, MN 55905, Email: smith.jay@mayo.edu Acknowledgement of Funding Sources Funding provided by Mayo Clinic Institutional Funds. This project was supported by Grant Number UL1 TR000135 from the National Center for Advancing Translational Sciences (NCATS). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. Neither funding source had a role in the study design, the collection, analysis and interpretation of data, the writing of the report or the decision to submit for publication. Declaration of Conflicting Interests Dr. Smith is Co-Founder and Chief Medical Officer for Sonex Health, LLC. Dr. Kakar is on the Medical Advisory Board for Sonex Health, LLC and is a consultant for Arthrex, Inc. and Skeletal Dynamics, LLC. Previous Presentation Results were presented in abbreviated form as a poster at the American Academy of Physical Medicine and Rehabilitation in October 2016. They have not been published, nor are they under consideration for publication elsewhere. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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