Anatomy
Extensor carpi ulnaris - lateral epicondyle to base of 5th metacarpal
6th extensor compartment at wrist
Subsheath
- underneath the extensor compartment
- maintains ECU in ulna groove via ulna sided labrum
- acts as ulna sided labrum to
Pathology
Tendinopathy
Subluxation
- sudden forced injury or repetitive microtrauma
- tear or stretching of the subsheath
- subluxes volar and ulna with supination
Subsheath tears
Ulna side
Radial side
Periosteum elevated to create a false pouch
Symptoms
Athletes - tennis players
Ulna sided wrist pain
Clicking or snapping of ECU with rotation
Ultrasound
Assess dynamic instability
MRI
Tendinopathy
Groove anatomy
ECU tendon sheath tears
Management
Options
Acute injury - ECU sheath repair
Chronic injury - ECU sheath reconstruction using extensor retinaculum
Technique
ECU reconstruction technique PDF
ECU reconstruction technique PDF 2
Dorsal approach
- protect dorsal branch ulna nerve
- ulna or radial based flap of extensor retinaculum
- ECU splits - < 50% tubularize / > 50% palmaris longus reconstruction
- repair sheath if able
- +/- groove deepening
- +/- wrap extensor retinaculum around ECU and suture to itself
Results
Peter et al Arch Orthop Trauma Surg 2019
- 12 patients with ECU subluxation
- treated with extensor retinaculum flap reconstruction
- 10/12 good or excellent outcome