subluxation

Definition

Loss of ligamentous stability between atlas and axis

Can cause impingement of the spinal cord

Etiology

Function

LHB primary function is humeral head depressor

Also accelerate / decelerate arm in overhead sports

Problems

Biceps problems usually occur with other pathology 

- rotator cuff / instability

3 main problems

1.  Degeneration

Epidemiology

6 /100 000

- second most common dislocation after shoulder

Mechanism

FOOSH

Goal

Subluxation & dislocation

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

Osteoarthritis

Clinical

More common problem

Anatomy

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

Mechanism

Forced supination, palmar flexion, and ulnar deviation