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We present a case of isolated Abductor Digiti Minimi (ADM) palsy caused by an anomalous branch from the ulnar artery. Electrophysiology suggested selective involvement of the motor branch to the ADM in the Guyon's canal. Surgical exploration revealed an anomalous branch of the ulnar artery causing a pincer effect on the nerve to the ADM. Division and ligation of this branch effectively decompressed the nerve and the patient recovered satisfactorily. This report highlights the need to consider vascular aberrations as a differential diagnosis for ulnar neuropathy in Guyon's canal.

A 43-year-old female is presented who underwent a two-stage tendon reconstruction and developed a low ulnar nerve palsy postoperatively. Exploration found that the tendon graft was passing through Guyon’s canal and that the ulnar nerve was divided. This is a previously unreported complication. The reconstruction is discussed, the literature reviewed and a guide is given on how to identify the correct tissue plane when passing a tendon rod.

Background: This study compares the sensitivity of continuous ultrasonographic scanning and ultrasonographic inching in the localisation of ulnar neuropathy at the elbow to diagnose the two common entrapment sites: retroepicondylar groove and cubital tunnel.

Methods: The charts of 30 patients who were diagnosed with ulnar neuropathy of the elbow and underwent ultrasonographic examinations using the inching and the continuous technique between April 2015 and September 2019 were reviewed. Sensitivities of ultrasonographic inching and continuous scanning were compared.

Results: A total of 34 elbows from 30 patients were examined. The sensitivities of continuous ultrasonographic scanning method and ultrasonographic inching were 85% and 71%, respectively, but this was not significant (p = 0.06). The maximum cross-sectional areas (CSAs) in continuous scanning were mainly found within the area from the medial epicondyle to the 2-cm distal point in the cubital tunnel entrapment, while a majority of the largest CSAs in ultrasonographic inching was observed at the medial epicondyle level in both entrapment sites. The mean of the maximum CSAs in continuous scanning (17.04 ± 6.75 mm²) was higher than that in ultrasonographic inching (14.13 ± 6.63 mm²), although this difference remained non-significant (p = 0.08). However, continuous scanning differed more significantly (p < 0.0001) from the cut-off value than the ultrasonographic inching (p < 0.0066).

Conclusions: Continuous scanning might be more suitable than ultrasonographic inching to localise ulnar neuropathy, which inherently has variations in the cubital tunnel anatomy and its entrapment points, when selecting optimal treatment based on the entrapment site.

Level of Evidence: Level III (Diagnostic)

A fracture of the distal radius with an associated injury to the ulnar nerve is rare. The management of the ulnar nerve lesion is unclear. We present a patient with a closed distal radius fracture related to an injury to the ulnar nerve associated with diminished sensation and a claw deformity. This was assessed by ultrasonography (US) that showed the nerve to be in continuity without any evidence of compression. The nerve was deviated towards the volar side at the distal end of the ulna and was enlarged at the same point. Open reduction and internal fixation was performed for the fracture. Emergent nerve exploration was not performed. The function of the ulnar nerve was completely restored at 16 weeks after injury. In cases presenting with ulnar nerve injury, we recommend US to evaluate the condition of the ulnar nerve. Nerve exploration should be performed when neurological deficits were found on US or symptoms did not recover over 4 months observation.

Level of Evidence: Level V (Therapeutic)

Background: Ulnar neuropathy after a distal radius fracture is rare and has limited reports in literature. As such, there is no consensus regarding the optimal treatment and management of such injuries. We report our experience with managing these uncommon injuries.

Methods: A retrospective review was conducted where patients presenting with ulnar neuropathy after sustaining a distal radius fracture were identified from January 2021 to December 2023 from our hospital database.

Results: A total of four patients were identified. All of them underwent surgical fixation for their respective fractures. None of them underwent immediate or delayed exploration and decompression of the ulnar nerve. All patients had clinical improvement at 3 months after their initial injuries. Three patients eventually had resolution of the neuropathy between 5 and 9 months post injury, while one had partial recovery and developed a neuroma but declined surgery due to symptoms minimally affecting work and daily activities.

Conclusions: Ulnar neuropathy after distal radius fractures may not be as rare as previously thought. Expectant management of the neuropathy would be a reasonable treatment as long as there is no evidence of nerve discontinuity or translocation and that there is clinical and/or electrodiagnostic improvement at 3–4 months after the initial injury.

Level of Evidence: Level IV (Therapeutic)