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

summary
- Lateral Ulnar Collateral Ligament Injury is a ligamentous elbow injury usually associated with a traumatic elbow dislocation, and characterized by posterolateral subluxation or dislocation of the radiocapitellar and ulnohumeral joints.
- Diagnosis can be made with plain radiographs of the elbow which may show an isolated elbow dislocation or an elbow dislocation with a radial head and coronoid tip fracture.
- Treatment may be nonoperative or operative depending on presence of concomitant elbow fractures, as well as elbow stability following reduction.

Etiology
- 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) vs. Valgus Posterolateral Rotatory Instabiliy (VPLRI)
                                        
                                            VPMRI
                                        
                                            VPLRI
                                        
                                            Radial head
                                        
                                            No radial head fracture
                                        
                                            Radial head fracture
                                        
                                            Coronoid fracture
                                        
                                            > 15% (anteromedial facet)
                                        
                                            < 15% (coronoid tip)
                                        
                                            MCL
                                        
                                            Posterior band of MCL ruptured, anterior band intact (attached to anteromedial facet)
                                        
                                            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

Varus Posteromedial Rotatory Instability (VPMRI) vs. Valgus Posterolateral Rotatory Instabiliy (VPLRI)
	VPMRI	VPLRI
Radial head	No radial head fracture	Radial head fracture
Coronoid fracture	> 15% (anteromedial facet)	< 15% (coronoid tip)
MCL	Posterior band of MCL ruptured, anterior band intact (attached to anteromedial facet)	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