A 33-year-old male patient presented a long history of medial elbow pain, forcing him to restrict daily activities. He had no trauma history or significant past medical history. He had tenderness and clicking on his right elbow on physical examination. There was no sensory deficit.
Magnetic resonance imaging (MRI) of the elbow is flexed and extended positions was performed. In fully extended elbow images, the ulnar nerve and medial triceps muscle were in the expected location, posterior to the medial epicondyle (Figure 1a, 1b). However, with elbow flexion, the ulnar nerve and the medial head of the triceps muscle were dislocated anterior to the medial epicondyle (Figure 2, 3). In addition, fat-suppressed proton density images showed increased intrinsic signal and calibre of ulnar nerve, consistent with ulnar neuropathy (Figure 1a, 1b).
Snapping triceps is a rare cause of medial elbow pain. It occurs when the distal part of the triceps subluxated over the medial epicondyle. Ulnar nerve dislocation may occur in combination with triceps dislocation. Occasionally, patients complain of ulnar neuropathy characterized by paresthesias and other sensory abnormalities in the ulnar nerve distribution. Ulnar nerve dislocation may occur in 16% to 20% of asymptomatic people [1].
Ulnar nerve compression occurs mainly at the elbow. The ulnar nerve is adjacent to the medial epicondyle of the humerus in the cubital tunnel [1]. The cubital tunnel changes shape when the elbow is flexed, causing increased pressure on the ulnar nerve. The repetitive motion of the ulnar nerve over the medial epicondyle can cause frictional neuritis [1]. The triceps muscle broadens during the elbow flexion because it is compressed against the distal humerus. Hence, the triceps tend to dislocate over the medial epicondyle [2].
Risk factors include cubital varus deformity, hypertrophy or prominence of the distal triceps muscle, or accessory head of the triceps [3].
Increased signal intensity on fluid-sensitive MR images is a non-specific finding seen in up to 60% of asymptomatic elbows. Evidence of other additional findings, such as changes in nerve diameter, is considered the presence of ulnar neuropathy [1]. Ulnar neuropathy can be due to either entrapment or other causes such as trauma, infection, inflammation, and tumoral lesions. Clinical examination with electromyography studies is the gold standard for diagnosing peripheral neuropathy [4].
Dynamic sonographic imaging can show dislocation of the medial triceps head and ulnar nerve during elbow flexion and relocation posteriorly during elbow extension. Ultrasound can also show a swollen and hypoechoic nerve, characteristic findings of ulnar neuropathy [1].
İnitially, conservative treatment should be employed. It involves nonsteroidal anti-inflammatory drugs and reducing exacerbating activities like weight lifting. After failing conservative treatment, surgery should be considered. Treatment includes stabilization of the nerve and resection of the snapping tendon [2].
Our patient was planned for surgery. The surgical evaluation confirmed ulnar nerve dislocation at 90 degrees elbow flexion and medial triceps dislocation approximately at 120 degrees elbow flexion. Then, the ulnar nerve and medial triceps muscle were fixed to normal anatomical position. Our patient returned to pain-free activity with the resolution of his snapping after surgery.
Clinical perspective
On physical exam, the dislocation of the ulnar nerve may be palpated as a snap during the examination. The second or third snap may be felted related to subluxation of the medial head triceps muscle and the triceps tendon. Snapping near the elbow is usually due to dislocation of the ulnar nerve. So clinicians may attribute all elbow snapping to the ulnar nerve. Nonetheless, the accompanying medial triceps dislocation diagnosis is critical for surgical planning. Unrecognization of the coexistence of ulnar nerve and medial triceps head dislocation will lead to persistent snapping after surgery [1]. For preventing misdiagnosis, an MRI scan should be performed.
Teaching points
Ulnar neuropathy at the elbow can be caused by static structures or by dynamic factors. Standard MRI with the extended elbow misses the dynamic abnormalities of elbow flexion [5]. The recognition of the coexistence of the ulnar nerve and medial triceps head dislocation is beneficial for proper preoperative planning [6]. Therefore, MRI in both flexed and extended positions should be performed.
Snapping triceps with ulnar nerve dislocation
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According to the provided MRI images, an abnormal displacement of soft tissue structures in the medial aspect of the elbow joint is noted at different degrees of flexion:
Considering the patient’s clinical history (persistent medial elbow pain, snapping or “clicking” sensation during movement, discomfort along the ulnar side) and the imaging findings, the following differential diagnoses are suggested:
Taking into account the patient’s age (33 years), repeated episodes of medial elbow pain and snapping, and the clear MRI evidence of medial head of the triceps and ulnar nerve displacement during flexion, the most likely diagnosis is:
The clinical presentation and dynamic MRI findings are strongly consistent with this diagnosis. To further assess the degree of ulnar nerve involvement, electromyography and nerve conduction studies may be conducted to evaluate for potential neuropathies affecting the fibular (peroneal) nerve or other nerves.
Disclaimer: This report is based on the available information and is intended for reference only. It should not replace an in-person consultation or professional medical advice. If you have further questions or if symptoms change, please seek timely medical evaluation to receive a personalized treatment plan.
Snapping triceps with ulnar nerve dislocation
