Basic Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Nov 18, 2022; 13(11): 978-985
Published online Nov 18, 2022. doi: 10.5312/wjo.v13.i11.978
Anatomic relationship of extensor indicis propius and extensor digitorum communis: Implications for tendon transfer
Joanne Zhou, Christopher Frey, Nicole Segovia, Jeffrey Yao
Joanne Zhou, Christopher Frey, Nicole Segovia, Jeffrey Yao, Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford University, Redwood city, CA 94063, United States
Author contributions: Zhou J contributed to study design, dissections, statistical analysis, and writing the manuscript; Frey C contributed to study design, dissections, statistical analysis, and writing the manuscript; Segovia N carried out statistical analyses and assisted with manuscript revisions; Yao J contributed to study design and manuscript revisions.
Institutional review board statement: This study was deemed exempt from Institutional Review Board Approval as only donated cadaveric specimens were used.
Informed consent statement: This study was deemed exempt from informed consent statement as only donated cadaveric specimens were used.
Conflict-of-interest statement: The authors have nothing to disclose.
Data sharing statement: The statistical methods of this study were reviewed by our research support center, and the statistical methods and techniques mentioned are appropriate for the research.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Joanne Zhou, MD, Staff Physician, Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford University, 450 Broadway Street Pavilion A 2nd Fl MC 6120, Redwood City, CA 94603, United States. zhoujy@stanford.edu
Received: June 23, 2022
Peer-review started: June 23, 2022
First decision: August 22, 2022
Revised: September 6, 2022
Accepted: October 19, 2022
Article in press: October 19, 2022
Published online: November 18, 2022
Processing time: 146 Days and 4.6 Hours
Abstract
BACKGROUND

The extensor indicis proprius (EIP) tendon is a frequently used donor for a variety of tendon transfers, most commonly for reconstruction of the extensor pollicis longus (EPL). EIP is known to have frequent anatomic variants including split tendons and variations in tendon arrangement.

AIM

To characterize the anatomy of the EIP at the level of the extensor retinaculum, where tendon harvest is often performed, and share our preferred technique for EIP to EPL transfer.

METHODS

Twenty-nine fresh-frozen cadaveric forearms without history of forearm or hand injury or surgery were dissected. Tendon circumference and relationship of the EIP and extensor digitorum communis to the index (EDCI) at the metacarpophalangeal (MCP) joint and the distal extensor retinaculum were recorded. Distance from the distal extensor retinaculum to the EIP myotendinous junction was measured.

RESULTS

EIP was ulnar to the EDCI in 96.5% of specimens (28/29) at the distal edge of the extensor retinaculum. In the remaining specimen, EIP was volar to EDCI. Tendon circumference at the distal extensor retinaculum averaged (9.3 mm ± 1.7 mm) for EDCI and 11.1 mm (± 2.7 mm) for EIP (P = 0.0010). The tendon circumference at the index MCP joint averaged 11.0 mm (± 1.7 mm) for EDCI and 10.6 mm (± 2.1 mm) for EIP (P = 0.33). EIP had a greater circumference in 76% (22/29) of specimens at the distal extensor retinaculum whereas EIP had a greater circumference in only 31% (9/29) of specimens at the MCP joint.

CONCLUSION

The EIP tendon is frequently ulnar to and greater in circumference than the EDCI at the distal extensor retinaculum, which can be taken into consideration for tendon transfers involving EIP.

Keywords: Surgical anatomy; Tendon transfer; Extensor digitorum communis; Extensor indicis proprius; Tendon harvest; Cadaveric Dissection

Core Tip: We found that extensor indicis proprius (EIP) was consistently ulnar to extensor digitorum communis to the index in 96.5% of specimens at the distal extensor retinaculum. The EIP had a greater circumference in 76% (22/29) of specimens at the distal extensor retinaculum. This research contributes to the body of knowledge on extensor tendon anatomy and facilitates the smaller incisions and dissection of EIP needed for tendon transfers.