Clinical characteristics and classification of deep branch of ulnar nerve injury_Chinese Journal of Reparative and Reconstructive Surgery

Authors：

 YANG Yong , JIN Antong , LIU Ran , JIANG Xuanyu , XUE Yunhao , SUN Liying , WANG Yang , LIU Chang , WANG Zhenzhong

Department of Hand Surgery, Beijing Jishuitan Hospital, Capital Medical University, Beijing, 100035, P. R. China;

Corresponding?author：

YANG Yong, Email: 0414yang@sina.com

Keywords：

Deep branch of the ulnar nerve; nerve injury; classification criteria; pisohamate hiatus

DOI：

10.7507/1002-1892.202604043

Video：

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Objective To investigate the clinical characteristics of deep branch of the ulnar nerve injuries at the wrist and hand and to summarize the classification criteria. Methods A retrospective analysis was conducted on 12 patients with deep branch of the ulnar nerve injuries at the wrist and hand admitted between November 2016 and September 2025, including 7 males and 5 females with an average age of 42.2 years (range, 17-69 years). The duration of injury ranged from 0.3 to 4.0 months (mean, 1.85 months). Two point discrimination (2-PD) of the little finger was 12 (4, 15) mm. The muscle strength of little finger abduction was rated as grade 3 in 1 case, grade 4^? in 6 cases, and grade 5 in 5 cases. Pinch strength between the thumb and index finger was (2.88±0.49) kg. Wartenberg sign was positive in 10 cases and negative in 2 cases. The index-middle finger crossing test was positive and claw-hand deformity was present in all patients. Ten patients underwent surgical treatment, whereas 2 patients received conservative treatment. Results Based on the anatomical characteristics of the deep branch of the ulnar nerve, clinical manifestations, and intraoperative exploration findings, injuries to the deep branch of the ulnar nerve at the wrist and hand were classified into three types. Type Ⅰ injuries were located proximal to the pisohamate hiatus; type Ⅱ injuries were located between the pisohamate hiatus and a point 17 mm distal to the hook of the hamate; and type Ⅲ injuries were located distal to a point 17 mm distal to the hook of the hamate. Among the 12 patients, 7 were rated as type Ⅰ injuries, 3 as type Ⅱ injuries, and 2 as type Ⅲ injuries. All patients were followed up 6-108 months after treatment (median, 15.5 months). At last follow-up, 2-PD of the little finger improved to 6 (4, 6) mm; the muscle strength of little finger abduction improved to grade 5^? in 3 patients and grade 5 in 9 patients; and pinch strength between the thumb and index finger increased to (6.53±1.12) kg. All differences between pre- and post-treatment were significant (P<0.05). Wartenberg sign, the index-middle finger crossing test, and claw-hand deformity were all negative. The all outcome indicators in the 7 patients with type Ⅰ injuries significantly improved when compared with those before treatment (P<0.05). Conclusion Based on the clinical characteristics and injury location, injuries to the deep branch of the ulnar nerve at the wrist and hand can be classified into three types. The pisohamate hiatus and the point 17 mm distal to the hook of the hamate on the palmar aspect are key anatomical landmarks for this classification. This classification system may facilitate accurate localization of deep ulnar nerve branch injuries and provide guidance for surgical planning.

Citation： YANG Yong, JIN Antong, LIU Ran, JIANG Xuanyu, XUE Yunhao, SUN Liying, WANG Yang, LIU Chang, WANG Zhenzhong. Clinical characteristics and classification of deep branch of ulnar nerve injury. Chinese Journal of Reparative and Reconstructive Surgery, 2026, 40(9): 1351-1358. doi: 10.7507/1002-1892.202604043 Copy

1.	Lee JH, Lee J, Park JS, et al. Characteristics of surgically treated Guyon canal syndrome: A multicenter retrospective study[J]. J Plast Reconstr Aesthet Surg, 2022, 75(9): 3269-3278.
2.	Li C, Wu JC, Lan C, et al. Prospective outcome analysis of ulnar tunnel syndrome: Comparing traumatic versus non-traumatic etiologies[J]. Asian J Surg, 2023, 46(1): 180-186.
3.	Saracco M, Panzera RM, Merico B, et al. Isolated compression of the ulnar motor branch due to carpal joint ganglia: clinical series, surgical technique and postoperative outcomes[J]. Eur J Orthop Surg Traumatol, 2021, 31(3): 579-585.
4.	Lui TH, Chu KM. Endoscopic release of the Guyon canal and pisohamate hiatus[J/OL]. Arthrosc Tech, 2019, 8(11): e1431-e1435. doi: 10.1016/j.eats.2019.05.033.
5.	Deeg J, Loizides A, L?scher W, et al. Cycling-related compressive neuropathy of the deep ulnar motor branch in the hand: is sonography a valid tool?[J]. Ultrasound Med Biol, 2021, 47(7): 1970-1975.
6.	Capitani D, Beer S. Handlebar palsy—a compression syndrome of the deep terminal (motor) branch of the ulnar nerve in biking[J]. J Neurol, 2002, 249(10): 1441-1445.
7.	Rohilla S, Yadav RK, Dhaulakhandi DB. Lipoma of Guyon’s canal causing ulnar neuropathy[J]. J Orthop Traumatol, 2009, 10(2): 101-103.
8.	Chiang L, Shieh S. Ganglion cyst in zone 2 of Guyon’s canal causing ulnar neuropathy with claw hand deformity: a case report and literature review[J]. Ann Plast Surg, 2025, 94(3S Suppl 1): S90-S94.
9.	李建峰, 邵新中, 周德貴, 等. 橈骨遠端骨折合并腕部尺神經損傷的診斷與治療[J]. 中華手外科雜志, 2007, 23(5): 295-296.
10.	趙亮, 王斌, 蒲四慶, 等. 橈骨遠端骨折合并腕部尺神經損傷六例分析[J]. 中國修復重建外科雜志, 2010, 24(4): 505-506.
11.	Gil YC, Shin KJ, Lee SH, et al. Anatomy of the deep branch of the ulnar nerve[J]. J Hand Surg (Eur Vol), 2016, 41(8): 843-847.
12.	Sloan EP. Nerve injuries in the hand[J]. Emerg Med Clin North Am, 1993, 11(3): 651-670.
13.	Maroukis BL, Ogawa T, Rehim SA, et al. Guyon canal: the evolution of clinical anatomy[J]. J Hand Surg (Am), 2015, 40(3): 560-565.
14.	Syamly S, Chaitra BR. A cadaveric study on variations of branching patterns of ulnar nerve in hand[J/OL]. Int J Anat Radiol Surg, 2021, 10(2): AO28-AO31. doi: 10.7860/IJARS/2021/48007:2640.
15.	Shea JD, McClain EJ. Ulnar-nerve compression syndromes at and below the wrist[J]. J Bone Joint Surg (Am), 1969, 51(6): 1095-1103.
16.	Wu JS, Morris JD, Hogan GR. Ulnar neuropathy at the wrist: case report and review of literature[J]. Arch Phys Med Rehabil, 1985, 66(11): 785-788.
17.	Tatagiba M, Penkert G, Samii M. Compression syndrome of the motor branch of the ulnar nerve. Case report and review of the literature[J]. Chirurg, 1990, 61(11): 849-852.
18.	Hayes JR, Mulholland RC, O’Connor BT. Compression of the deep palmar branch of the ulnar nerve. Case report and anatomical study[J]. J Bone Joint Surg (Br), 1969, 51(3): 469-472.
19.	Almeida V, de Carvalho M. Lesion of the deep palmar branch of the ulnar nerve: causes and clinical outcome[J]. Neurophysiol Clin, 2010, 40(3): 159-164.
20.	Chen SH, Tsai TM. Ulnar tunnel syndrome[J]. J Hand Surg (Am), 2014, 39(3): 571-579.
21.	Fones L, Freedman MK, Beredjiklian PK, et al. Dorsal interosseous muscle weakness from mid-palm ganglion cyst[J]. Arch Bone Jt Surg, 2025, 13(2): 119-124.

1. Lee JH, Lee J, Park JS, et al. Characteristics of surgically treated Guyon canal syndrome: A multicenter retrospective study[J]. J Plast Reconstr Aesthet Surg, 2022, 75(9): 3269-3278.
2. Li C, Wu JC, Lan C, et al. Prospective outcome analysis of ulnar tunnel syndrome: Comparing traumatic versus non-traumatic etiologies[J]. Asian J Surg, 2023, 46(1): 180-186.
3. Saracco M, Panzera RM, Merico B, et al. Isolated compression of the ulnar motor branch due to carpal joint ganglia: clinical series, surgical technique and postoperative outcomes[J]. Eur J Orthop Surg Traumatol, 2021, 31(3): 579-585.
4. Lui TH, Chu KM. Endoscopic release of the Guyon canal and pisohamate hiatus[J/OL]. Arthrosc Tech, 2019, 8(11): e1431-e1435. doi: 10.1016/j.eats.2019.05.033.
5. Deeg J, Loizides A, L?scher W, et al. Cycling-related compressive neuropathy of the deep ulnar motor branch in the hand: is sonography a valid tool?[J]. Ultrasound Med Biol, 2021, 47(7): 1970-1975.
6. Capitani D, Beer S. Handlebar palsy—a compression syndrome of the deep terminal (motor) branch of the ulnar nerve in biking[J]. J Neurol, 2002, 249(10): 1441-1445.
7. Rohilla S, Yadav RK, Dhaulakhandi DB. Lipoma of Guyon’s canal causing ulnar neuropathy[J]. J Orthop Traumatol, 2009, 10(2): 101-103.
8. Chiang L, Shieh S. Ganglion cyst in zone 2 of Guyon’s canal causing ulnar neuropathy with claw hand deformity: a case report and literature review[J]. Ann Plast Surg, 2025, 94(3S Suppl 1): S90-S94.
9. 李建峰, 邵新中, 周德貴, 等. 橈骨遠端骨折合并腕部尺神經損傷的診斷與治療[J]. 中華手外科雜志, 2007, 23(5): 295-296.
10. 趙亮, 王斌, 蒲四慶, 等. 橈骨遠端骨折合并腕部尺神經損傷六例分析[J]. 中國修復重建外科雜志, 2010, 24(4): 505-506.
11. Gil YC, Shin KJ, Lee SH, et al. Anatomy of the deep branch of the ulnar nerve[J]. J Hand Surg (Eur Vol), 2016, 41(8): 843-847.
12. Sloan EP. Nerve injuries in the hand[J]. Emerg Med Clin North Am, 1993, 11(3): 651-670.
13. Maroukis BL, Ogawa T, Rehim SA, et al. Guyon canal: the evolution of clinical anatomy[J]. J Hand Surg (Am), 2015, 40(3): 560-565.
14. Syamly S, Chaitra BR. A cadaveric study on variations of branching patterns of ulnar nerve in hand[J/OL]. Int J Anat Radiol Surg, 2021, 10(2): AO28-AO31. doi: 10.7860/IJARS/2021/48007:2640.
15. Shea JD, McClain EJ. Ulnar-nerve compression syndromes at and below the wrist[J]. J Bone Joint Surg (Am), 1969, 51(6): 1095-1103.
16. Wu JS, Morris JD, Hogan GR. Ulnar neuropathy at the wrist: case report and review of literature[J]. Arch Phys Med Rehabil, 1985, 66(11): 785-788.
17. Tatagiba M, Penkert G, Samii M. Compression syndrome of the motor branch of the ulnar nerve. Case report and review of the literature[J]. Chirurg, 1990, 61(11): 849-852.
18. Hayes JR, Mulholland RC, O’Connor BT. Compression of the deep palmar branch of the ulnar nerve. Case report and anatomical study[J]. J Bone Joint Surg (Br), 1969, 51(3): 469-472.
19. Almeida V, de Carvalho M. Lesion of the deep palmar branch of the ulnar nerve: causes and clinical outcome[J]. Neurophysiol Clin, 2010, 40(3): 159-164.
20. Chen SH, Tsai TM. Ulnar tunnel syndrome[J]. J Hand Surg (Am), 2014, 39(3): 571-579.
21. Fones L, Freedman MK, Beredjiklian PK, et al. Dorsal interosseous muscle weakness from mid-palm ganglion cyst[J]. Arch Bone Jt Surg, 2025, 13(2): 119-124.

Chinese Journal of Reparative and Reconstructive Surgery

Clinical characteristics and classification of deep branch of ulnar nerve injury

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