Posterolateral Rotatory Instability

Definition

 

Radius rotates externally in relation to the ulna

- posterior displacement of the radial head relative to the capitellum

- in flexion

 

Posterolateral rotatory Instability

 

Anatomy LCL

 

LCL Elbow

 

Pathology

 

1.  Laxity or tear of ulna LCL

- posterior dislocation / subluxation / perching

- most common cause

 

2.  Torn CEO

- dynamic restraint

 

3.  Depressed fracture of radial head / malunion coronoid fractures

- leading to loss of secondary restraint

 

Mechanism

 

Dislocation occurs with a valgus ER force pivoting the elbow on the intact MCL

 

Aetiology

 

Trauma

- acute LCL tear after dislocation

 

Iatrogenic

- tennis elbow release

- Kocher approach

 

Ligamentous laxity

 

Long standing cubitus varus

 

History

 

Posterolateral elbow pain

 

Describe clunk on full extension

 

Patient may be able to demonstrate instability

 

Examination

 

Test combines external rotation / supination with valgus and axial loading

 

1.  O'Driscoll Pivot Shift Test

 

Best with patient anaesthetised

- can sublux joint

 

If patient awake, only get pain and apprehension

 

Patient supine

- examiner at head of bed

- GHJ full flexed with hand over head

- elbow resembles knee in this position

- forearm supinated

- elbow fully extended

 

Valgus stress with axial load & slowly flex joint

- at 40o the radial head is subluxed maximally posterolaterally

- radial head becomes prominent as it dislocates

- patient feels apprehension as the radial head subluxes

- past 40o flexion the radial head reduces

 

Positive

- prominent radial head (dislocates)

- pivot

- pain  (apprehension)

- maximum subluxation is at 40o flexion but with increased flexion reduces with snap

 

2.  Table Top Test

 

Push up on table with forearms in supination

- radial head subluxes, patient has apprehension

- relieved by thumb pressing on radial head

 

Table Top Test 1Table Top Test BeforeTable Top Test After

 

X-ray

 

 

Usually normal

- may be slight widening of radiohumeral joint

- radial head may appear slightly posterior

 

MRI

 

Difficult to distinguish lateral complex

 

Management

 

NHx

 

Does not improve with time

- usually requires surgery if very symptomatic

 

Options

 

1. Repair 

2. Imbricate

3. Reinforce/Reconstruct with PL graft

 

Reconstruction

 

Kocher approach between Anconeus & ECU

- drill holes x 2 base sublime tubercle

- drill holes x 2 at lateral epicondyle (isometric point)

- palmaris graft in figure of 8

- tighten with elbow at 30 - 40o of flexion

 

Post op

- hold flexed 2/52

- then allow ROM in hinged brace

 

Lateral Ligament Elbow Reconstruction

 

Results

 

O'Driscoll et al JBJS Br 2005

- retrospective review of 44 cases

- some direct repair, some autograft reconstruction

- 86% satisfaction

- better outcomes in reconstruction group