Atlanto-axial instability
Definition
Loss of ligamentous stability between atlas and axis
Can cause impingement of the spinal cord
Etiology
Loss of ligamentous stability between atlas and axis
Can cause impingement of the spinal cord
LHB primary function is humeral head depressor
Also accelerate / decelerate arm in overhead sports
Biceps problems usually occur with other pathology
- rotator cuff / instability
3 main problems
1. Degeneration
6 /100 000
- second most common dislocation after shoulder
FOOSH
Diagnosis
Pisotriquetral view
- forearm positioned 30° supinated off the neutral position
- loss of symmetry between the pisiform and triquetrum is required for the diagnosis
- carpal tunnel view may be helpful in further assessment of the joint
Clinical
More common problem
6th compartment
- fibro-osseous tunnel overlying 1.5 cm to 2.0 cm of distal ulna
- held tight by the extensor carpi ulnaris tendon sheath
- the extensor retinaculum passes around the ulna to insert on the palmar aspect of the carpus
- extensor retinaculum is a separate structure from the ECU tendon sheath
Forced supination, palmar flexion, and ulnar deviation