Lateral Ulnar Collateral Ligament Injury (PLRI) - Shoulder & Elbow

Introduction

A form of elbow instability characterized by posterolateral subluxation or dislocation of the radiocapitellar and ulnohumeral joints
- usually associated with a traumatic elbow dislocation
- caused by insufficiency of the lateral elbow collateral ligament complex
  - caused primarily by insufficiency of the LUCL
Pathophysiology
- traumatic
  - most often discussed as a result of elbow dislocation
    - combination of forearm supination, axial loading, valgus (posterolateral) stress, and elbow extension causes progressive failure of the lateral collateral ligament complex and anterior capsule, resulting posterolateral subluxation of the radial head and external rotation of the semilunar notch away from trochlea
    - common extensor origin can also be avulsed
    - radioulnar articulation remains intact
- iatrogenic injury
  - from arthroscopic or open procedures of the lateral elbow that go posterior to equator of radial head (e.g. debridement of lateral epicondylitis)
    - arthroscopic debridement should be kept anterior to equator of the radial head
- chronic attenuation
  - secondary to chronic cubitus varus malunion
    - abnormal lateral thrust stretches out the LUCL with time
    - abnormal triceps vector further stretches LUCL
Associated conditions
- elbow dislocations

Anatomy

Lateral collateral ligament complex consists of 4 components
- accessory lateral collateral ligament
- annular ligament
- lateral radial collateral ligament (LCL)
- lateral ulnar collateral ligament (LUCL)
  - LUCL is the primary stabilizer to varus & ER stress
    - origin
      - lateral humeral epicondyle
    - insertion
      - the tubercle of the supinator crest of the ulna

Presentation

Symptoms
- pain is the primary symptom
- mechanical symptoms (clicking, catching, etc.)
  - often with elbow extension and when pushing off from arm of chair
Physical exam
- inspection and palpation
  - tenderness over LUCL
- motion and stability
  - varus instability
- provocative tests
  - lateral pivot-shift test
    - patient lies supine with affected arm overhead; forearm is supinated and valgus stress is applied while bringing the elbow from full extension to 40 degrees of flexion
    - with increased flexion, triceps tension reduces the radial head
    - often more reliable on anesthetized patient
  - posterior drawer test
    - patient lies supine with affected arm overhead; forearm is supinated and the examiner's index finger is placed under the radial head and the thumb over it.
    - application of a posterior force will cause posterior subluxation of the radial head
  - apprehension test
    - patient lies supine with affected arm extended overhead; forearm is supinated and valgus stress is applied while flexing the elbow
  - chair rise test
  - table-top relocation test
  - floor push-up test
    - patient cannot do push-ups with forearm supinated

Imaging

Radiographs
- recommended views
  - AP and lateral views of elbow
- findings
  - important to rule out associated fractures and confirm concentric reduction in setting of acute dislocation
  - standard radiographs are often of little value in evaluating PLRI
    - fluoroscopic imaging during provocative testing (e.g. pivot-shift) may demonstrate radial head subluxation
MRI
- indications
  - may not be helpful in the setting of recurrent instability and LUCL attenuation as visualizing ligament difficult due to oblique course
- findings
  - can identify acute avulsion of LUCL in acute instability
- sensitivity and specificity
  - LUCL pathology identifed in 50% of patients

Differential

	Varus Posteromedial Rotatory Instability (VPMRI)	Valgus Posterolateral Rotatory Instabiliy (VPLRI)
Radial head	No radial head fracture	Radial head fracture
Coronoid fracture	>15% (anteromedial facet)	<15% (tip fracture)
MCL	Posterior band of MCL ruptured, anterior band intact	Anterior band of MCL ruptured
LCL	LCL complex (includes LUCL) avulsion	LCL complex (includes LUCL) avulsion
Physical exam	Valgus stress, moving valgus, milking maneuver	Varus stress, chair rise, lateral pivot shift

Treatment

Nonoperative
- acute reduction followed by immobilization at 90° flexion for 5-7 days
  - indications
    - acute elbow dislocations
  - technique
    - following reduction assess post-reduction stability
    - place in posterior splint for 5-7 days, with elbow at 90 degrees of flexion and forearm appropriately positioned based on post-reduction stability
      - LCL disrupted, but MCL intact
        
        splint in full pronation (tightens lateral structures)
      - LCL + MCL disrupted
        
        splint in neutral
      - will not splint in full supination (for MCL rupture only) as the LCL is always disrupted in PLRI
    - early active ROM following splint removal (+/- extension block)
      - full supination/pronation from 90° to full flexion
      - progress with increasing extension by 30° weekly, but with the forearm in full pronation; after 6 weeks full supination in extension allowed
- bracing, extensor strengthening, activity modification w/ avoidance of gravity varus positions
  - indications
    - mild, chronic PLRI
    - low-demand patients
Operative
- open reduction, fracture fixation, LUCL repair
  - indications
    - osteochondral fragment or soft-tissue entrapment prevents concentric reduction
    - complex dislocation (associated fractures are present)
    - acute instability
      - open & arthroscopic techniques described
- LUCL reconstruction w/ graft
  - indications
    - chronic PLRI

Techniques

Reconstruction of LUCL complex
- approach
  - posterior mid-line
  - Kocher approach
- graft types
  - autograft or allograft tissue may be used
    - palmaris longus most common
    - gracilis and triceps fascia also utilized
- graft configuration
  - tendon graft tied to itself over lateral column after placing through tunnel in supinator crest & then weaving through "Y" tunnel configuration in humerus
  - it is critical that the graft covers > posterior 25% of the radial head to create a sling
  - graft can be plicated to capsule to maintain position and capsule plicated to augment repair
  - graft secured with arm in neutral rotation and 45° of flexion
- graft fixation
  - graft may be "docked" on humerus with sutures exiting "Y" tunnels or on both humeral and ulnar sides with interference screws (or sutures tied over bone - overlay technique)
- coronoid fracture ORIF / anterior capsular laxity
  - large fragments should be fixed with screw from dorsal ulnar surface (aided by ACL type guide to improve accuracy
  - small fragments should be excised but a suture plication of the anterior capsule to the broken tip increases stability and can be placed with the aid of ACL type guide
- postoperative
  - protected from varus stress across the elbow and shoulder abduction post-operatively (locked hinge brace)
  - early range-of-motion encouraged (+/- extension block with progressive gain to full extension and supination by 6-8 weeks)
  - important to keep forearm in full pronation during ROM until after 6 weeks (as above)

Complications

Recurrent instability
- 3-8% incidence
Infection
Cutaneous nerve injury
- decreased risk with posterior mid-line approach
Decreased ROM