What is the treatment approach for ulnar nerve transposition?

Ulnar Nerve Transposition Treatment Approach

Surgical transposition of the ulnar nerve is the recommended treatment for ulnar nerve entrapment that has failed conservative management, with subcutaneous transposition being the preferred first-line surgical approach due to its effectiveness and lower complication rates. 1, 2

Diagnostic Evaluation Before Transposition

• MRI with T2-weighted neurography is the reference standard for imaging ulnar nerve entrapment, showing characteristic high signal intensity and nerve enlargement 3, 1
• Ultrasound is an effective alternative diagnostic tool with high accuracy (sensitivity 77-79%, specificity 94-98%) for assessing cross-sectional area and nerve thickness 3, 1
• Dynamic ultrasound is particularly helpful in demonstrating nerve dislocation in ulnar nerve neuropathy and snapping triceps syndrome 3
• Shear-wave elastography has shown excellent diagnostic accuracy with reported 100% specificity and sensitivity for diagnosing ulnar neuropathy at the elbow 3, 1

Types of Ulnar Nerve Transposition

Subcutaneous Transposition

• Recommended as first-line surgical approach for most cases of ulnar nerve entrapment requiring transposition 2, 4
• Advantages include being less invasive, technically simpler, and having lower complication rates 2
• Stabilized subcutaneous transposition prevents the nerve from slipping back to the cubital tunnel 2
• Particularly effective for recurrent cubital tunnel syndrome, with 75% of patients achieving good to excellent outcomes 4

Intramuscular Transposition

• Indicated for chronic cubital tunnel syndrome with symptoms refractory to conservative therapy 5
• Requires creation of a shallow trough with resection of all fibrous septae to avoid scar formation 5
• Postoperative immobilization for 3 weeks is recommended, followed by range-of-motion exercises 5
• Most patients can resume regular activities by 8 weeks post-surgery 5

Endoscopic Transposition

• Emerging minimally invasive technique that offers advantages over open procedures 6, 7
• Benefits include smaller incisions, less local symptoms, reduced vascular insult to the nerve, and faster recovery 6
• Two-portal technique allows for endoscopy-assisted anterior subcutaneous transposition 7
• Particularly useful when the ulnar nerve is located in a "hostile bed" (e.g., osteophytes, scarring, ganglions) 6

Indications for Specific Transposition Techniques

• Subcutaneous transposition is indicated for most cases of ulnar neuropathy requiring surgery 2, 4
• Intramuscular transposition is appropriate for chronic cases refractory to conservative management 5
• Endoscopic transposition should be considered when minimizing tissue trauma is a priority 6, 7
• Transposition (any technique) is specifically indicated when there is symptomatic ulnar nerve instability 6

Common Pitfalls and Complications

• Incomplete decompression is the most common cause of persistent symptoms after surgery 5
• Critical sites of potential persistent compression include:
  • The medial intermuscular septum 5, 4
  • The arcade of Struthers 5
  • Fibrous bands proximal or distal to the cubital tunnel 5
  • The arcuate ligament of Osborne 5
  • Spinner's ligament or other fascial slings 5
• Excessive elbow flexion (>90°) during positioning should be avoided as it increases risk of ulnar neuropathy 1
• Proper positioning during surgery is critical, with either supination or neutral forearm position recommended 8

Postoperative Management

• Regular follow-up is essential to monitor for improvement of symptoms 1
• Range of motion and strengthening exercises help maintain function after appropriate healing period 1
• For pain management, paracetamol (up to 4g/day) is recommended as first-line oral analgesic 1
• Topical NSAIDs can provide localized pain relief with fewer systemic side effects 1