Cubital Tunnel Syndrome Caused by Anconeus Epitrochlearis Muscle

Abstract

Objective: We evaluated the clinical manifestation and surgical results following operative treatment of cubital tunnel syndrome (CuTS) caused by anconeus epitrochlearis (AE) muscle.

Methods: Among 142 patients who underwent surgery for CuTS from November 2007 to October 2015, 12 were assigned to the AE group based on discovery of AE muscle; 130 patients were assigned to the other group. We analyzed retrospectively; age, sex, dominant hand, symptom duration, and weakness in hand. Severity of the disease was evaluated using the Dellon classification and postoperative symptom were evaluated using disability of arm shoulder and hand (DASH) and visual analogue scale (VAS) scores. Surgery consisted of subfascial anterior transposition following excision of AE muscle.

Results: AE muscle was present in 8.5% of all patients, and was more common in patients who were younger and with involvement of their dominant hand; the duration of symptom was shorter in patients with AE muscle. All patients showed postoperative improvement in symptoms according to DASH and VAS scores.

Conclusion: The possibility of CuTS caused by AE muscle should be considered when younger patients have rapidly aggravated and activity-related cubital tunnel symptoms with a palpable mass in the cubital tunnel area. Excision of AE muscle and anterior ulnar nerve transposition may be considered effective surgical treatment.

Keywords: Anconeus epitrochlearis; Anterior subfascial transposition; Cubital tunnel syndrome; Ulnar nerve.

Fig. 1.

A and B : A 23-year-old male patient had surgery for cubital tunnel syndrome. The radiograph showed no definitive abnormality. C and D : Transverse and sagittal T2-weighted magnetic resonance imaging of the elbow showed anconeus epitrochlearis (AE) muscle (asterisk). E : Intraoperative finding revealed AE muscle (asterisk) above the cubital tunnel. F : After resection of the AE muscle, the compressed ulnar nerve was shown (G). H : Subfascial anterior transposition of the ulnar nerve was performed. ME : medial epicondyle, Ole : olecranon, Ulnar N : ulnar nerve.

Fig. 2.

Intra-operative findings. A : An anconeus epitroclearis (AE) ligament (arrow). B : After resection of AE ligament. ME : medial epicondyle, Ole : olecranon.