Zhou Joanne, Frey Christopher, Segovia Nicole, Yao Jeffrey
Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford University, Redwood city, CA 94063, United States.
World J Orthop. 2022 Nov 18;13(11):978-985. doi: 10.5312/wjo.v13.i11.978.
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.
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.
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.
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 ( = 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 ( = 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.
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.
示指固有伸肌（EIP）肌腱是多种肌腱转位常用的供体，最常用于重建拇长伸肌（EPL）。已知EIP常有解剖变异，包括肌腱分裂和肌腱排列变异。
描述在常进行肌腱取材的伸肌支持带水平EIP的解剖结构，并分享我们首选的EIP转位至EPL的技术。
解剖29个无前臂或手部损伤或手术史的新鲜冷冻尸体前臂。记录肌腱周长以及在掌指关节（MCP）和远端伸肌支持带处EIP与指总伸肌（EDCI）的关系。测量从远端伸肌支持带到EIP肌腱-肌腹交界处的距离。
在伸肌支持带远端边缘，96.5%（28/29）的标本中EIP位于EDCI尺侧。在其余标本中，EIP位于EDCI掌侧。远端伸肌支持带处EDCI的肌腱平均周长为（9.3 mm±1.7 mm），EIP为11.1 mm（±2.7 mm）（P = 0.0010）。在示指MCP关节处，EDCI的肌腱平均周长为11.0 mm（±1.7 mm），EIP为10.6 mm（±2.1 mm）（P = 0.33）。在远端伸肌支持带处，76%（22/29）的标本中EIP周长更大，而在MCP关节处只有31%（9/29）的标本中EIP周长更大。
在远端伸肌支持带处，EIP肌腱常位于EDCI尺侧且周长更大，这在涉及EIP的肌腱转位中可予以考虑。
