Modern Study Review (AI-Generated)
High-Yield Summary
Ulnar nerve palsy is a common peripheral neuropathy causing intrinsic hand muscle weakness, clawing deformity, and loss of fine motor function, particularly affecting grip and pinch strength. Clinically, it is classified as low or high palsy depending on the lesion site relative to the elbow, with distinct functional deficits and surgical considerations. Restoration of thumb adduction and intrinsic hand function is critical to regain hand utility. Modern management balances timely nerve repair with tendon transfers and joint stabilization to optimize pain-free function and hand dexterity.
Key Diagnostic Findings
| Aspect | Details |
|---|---|
| Anatomy | Ulnar nerve innervates intrinsic hand muscles (adductor pollicis, interossei, lumbricals 3-4), FDP to ring and little fingers, and sensory distribution to ulnar 1.5 fingers. |
| Clinical Presentation | – Weak pinch due to adductor pollicis paralysis – Weak grip from intrinsic muscle paralysis – Clawing of ring and little fingers (MCP hyperextension, IP flexion) – Sensory loss in ulnar nerve distribution (variable) |
| Imaging/Studies | – Nerve conduction studies and EMG to localize lesion and assess severity – Ultrasound/MRI for nerve continuity or compression causes |
| Classification Systems | – Low Ulnar Nerve Palsy: Lesion distal to the elbow, sparing FDP to ring/little fingers – High Ulnar Nerve Palsy: Lesion at or above elbow, involving FDP to ring/little fingers |
Current Gold Standard Treatment
| Treatment Type | Indications & Techniques |
|---|---|
| Non-operative | – Mild neuropraxia or incomplete palsy – Splinting to prevent clawing (intrinsic plus splint) – Occupational therapy for hand function |
| Operative | – Nerve repair or grafting for high lesions with discontinuity – Tendon transfers for intrinsic restoration when nerve recovery is inadequate or delayed – Joint stabilization procedures to prevent MCP hyperextension and clawing |
| Tendon Transfers for Thumb Adduction | – FDS of ring finger transfer (Brand) – Brachioradialis or ECRL with free tendon graft (Boyes) – Split FDS transfers (Royle-Thompson, Omer) |
| Tendon Transfers for Intrinsic Function | – FDS transfer from volar to dorsal side (Bunnell) – Split EDC tendons under deep transverse metacarpal ligament (Fowler) – ECRL/ECRB with free tendon graft (Brand) |
| MCP Stabilization Procedures | – Volar capsulodesis (Zancolli) – Tenodesis (Riordan) |
| High Ulnar Nerve Palsy Specific | – FDP to ring and little fingers paralyzed; restore flexion by suturing FDP tendons of ring/little fingers to long finger FDP |
Modern Complications & Outcomes
- Complications: Persistent claw deformity, incomplete restoration of pinch/grip strength, donor site morbidity from tendon transfers, joint stiffness, and sensory deficits.
- Outcomes: Early intervention and appropriate tendon transfers improve functional outcomes; MCP stabilization is crucial to prevent deformity and optimize finger flexion/extension balance.
- Board Exam Pearls:
- Clawing is due to intrinsic muscle paralysis causing MCP hyperextension and IP flexion.
- FDS transfer is contraindicated in high ulnar palsy due to FDP paralysis of ring/little fingers.
- Volar capsulodesis stabilizes MCP joints, allowing extrinsic muscles to function effectively.
- Restoration of thumb adduction (adductor pollicis) is essential for pinch strength.
Classic Clinical Notes
Ulnar Nerve Palsy
Low Ulnar Nerve Palsy
- The major functional deficits are weakness of pinch (adductor pollicis), weakness of grip (intrinsic paralysis), and sometimes clawing of the ring and little fingers.
- Weakness of pinch secondary to loss of thumb ADDUCTION (adductor pollicis paralysis).
- This should be restored, as it represents a major loss of function.
Transfers to restore thumb adduction:
- FDS of 4 swung over to thumb (Brand)
- Brachioradialis or ECRL to a free tendon graft (plantaris or palmaris longus) through the 3-4 interspace, then through the palm to the thumb (Boyes)
- FDS of 4 split into two limbs then swung over to thumb (Royle-Thompson)
- FDS of 4 split into 3 limbs, one to the thumb, the other two transferred dorsally to 4 and 5 to restore intrinsic function (Omer)
- The loss of intrinsic power makes grip weak.
Transfers to restore intrinsic power:
- FDS transfer from volar to dorsal (Bunnell)
- EDC 3 and 4 split then transferred under deep transverse metacarpal ligament then dorsally again (Fowler)
- ECRL or ECRB to a free plantaris graft (divided into 4) then transferred under deep transverse metacarpal ligament, then dorsally again (Brand)
- To prevent the clawing, the MCPs should be stabilized so that they don’t fall into hyperextension (this allows the fingers to be flexed by the extrinsics and extended by the extrinsics).
Procedures to stabilize the MCPs:
- Volar capsulodesis (Zancolli)
- Tenodesis (Riordan)
High Ulnar Nerve Palsy
- All the same applies, but you cannot use FDS of 4 because its FDP is also paralyzed.
- Flexion of the ring and little finger can be restored by suturing their FDPs to that of the long FDP.
Last Updated on January 24, 2026 by orthonet
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