Elbow instability

Traumatic Elbow Instability

Evaluation

• Neurovascular exam pre and post reduction
• X-ray assessment
• Reduction: correct medial or lateral displacement first, f/b pressure to posterior olecranon to bring anterior over trochlea
• Muscle relaxation is key
• Palpable / audible "clunk" good sign re: stability
• Assess post-reduction x-rays, ipsilateral UE for associated injuries: 10-15%
• Don't forget DRUJ, Int. Mem.  
• Range Elbow Joint
• Assess valgus stability with forearm pronated (to lock the lateral side)
• Assess potential for redislocation in extension: signifies unstable elbow
• Post-Reduction x-rays:
• AP and lateral
• Check for congruency
• Incongruent reduction: widening, osteochondral fragments, rotary instability
   
   
  Anatomy
   
  Primary Stabilizers
   Primary Static Stabilizers
  1.Ulnohumeral Joint
  2.MCL
  3.LCL, esp. LUCL
   
  Secondary Stabilizers
   
    Secondary Stabilizers
  1.Radial Head
  2.Capsule
  3.Flexor / pronator and extensor masses
   
  Dynamic Stabilizers
    Dynamic Stabilizers
  Muscles that cross the elbow and provide joint compressive forces
• Anconeus
• Triceps
• Brachialis
   
  Descriptive Classification
    Posterior
  Posterolateral: >90%
  Posteromedial
  Anterior
  Lateral
  Medial
  Divergent: rare
   
  Mechanism of Injury
    Posterior Dislocation
  F.O.O.S.H.
• Elbow extension
• Valgus force
• Forearm supination

Anterior Dislocation
Elbow flexed
Direct force to posterior forearm
 
Pathoanatomy
  Mechanism usually involves posterolateral pattern
Progression of Injury: lateral to medial
 

Stage 1: LCL, usually ulnar portion
Leads to posterolateral rotary subluxation
Rotary instability
 

Stage 2: anterior and posterior disruption
Leads to posterolateral dislocation as coronoid is perched on trochlea
Varus instability

Stage 3A: all soft tissue stabilizers except ant. MCL disrupted
Intact ant. MCL provides some stability if forearm pronated
Commonly seen along with radial head & coronoid fx
Stage 3B: entire MCL disrupted
Rotary, Varus, Valgus  instability
Stage 3C: entire distal humerus stripped of soft tissue
Instability despite LAC @ 90°  
 

Definitions
  Simple Dislocation
Dislocation of ulnohumeral joint without associated fracture
 

Complex Dislocation
Dislocation of ulnohumeral joint with associated fracture about the elbow
 

Terrible Triad
Elbow dislocation, radial head and coronoid fracture   
 

Simple Dislocation: Treatment +§+Recurrent Instability: 1-2%
Concentric stable reduction: post. splint  @ 90° w/ struts
Repeat radiographs @ 3-5, 10-14 days confirming reduction
Immobilize <3 weeks
Start gentle AROM

Increase extension over next 3 weeks
Vigorous PROM associated with H.O.
Patient apprehension with terminal extension: orthosis with block
 

Josefsson PO et al CORR 1987;221:221-225
Prospective Study of Simple, Closed Elbow Dislocations
31 simple elbow dislocations taken to OR for EUA, open exploration
9 redislocated easily with EUA; tendency to redislocate was associated with degree of flexor / pronator and extensor mass disruption
Complete disruption of medial and lateral collateral ligaments found in every case, usually at the humeral insertion.
 

Mehlhoff TL et al JBJS 1988;70: 244-249
52 simple elbow dislocations treated closed, average follow-up >34 months
Duration of immobilization before motion varied
No excellent outcomes in elbows immobilized >2 weeks
Immobilization for 4 weeks yielded all fair or poor results
No fair or poor results in elbows immobilized <18 days
"The results indicate that early active motion is the key factor in rehabilitation of the elbow after dislocation."
 
Complex Dislocation +§+Elbow Dislocation with Associated Elbow Fracture:
Radial head (5-11%)
Coronoid (5-10%)
Medial or Lateral Epicondyle (12-34%) 

Classic Study discussing treatment of radial head fractures associated w/ elbow dislocation

Broberg MA and Morrey BF CORR 1987 216: 109-119
24 patients with type IV radial head fracture, 2-35 yr. follow up
Treatment: 10 closed, 14 open
6/10 closed required further treatment
14 open: 5 partial, 5 complete radial head excision, 3 Silastic implants, 1 ORIF
Conclusion: prognosis better than anticipated
3 excellent / 15 good / 6 fair
Best results: Mason II treated closed, Mason III complete excision
Early treatment: reduce elbow, treat fracture accordingly
Immobilization >4 weeks should be avoided  

Contemporary Study discussing treatment of radial head fractures associated w/ elbow dislocations

Doornberg JN et al JBJS 2007;89:1075-80
27 consecutive complex elbow dislocations: 11 type II, 16 type III (13 terrible triad injuries) radial head fractures
Treated with "loose" fitting modular radial head prosthesis
13 excellent / 9 good / 3 fair / 2 poor according to Mayo Elbow Performance Index
Stability restored in all 27 elbows
68% demonstrated radiographic evidence of lucency around stem
7 reoperations / 9 capitellar arthrosis / 13 heterotopic ossification
Points / prosthesis indications: Mason III with >3 articular fragments, lost or irreparable fragments
Type IV radial head fractures consistently involve >30% radial head
Fractures typically involve most important area of radial head: anterolateral portion; buttress against posterior dislocation
Fractures often comminuted with wide displacment, fragments often lost or irreparable
 
Cohen and Hastings JAAOS 1998 §Operative Indications:
1.Elbow requires flexion >50-60% to remain reduced
2.Unstable fractures about the elbow joint 
Terrible Triad +1.+Elbow Dislocation
2.Radial Head Fracture
3.Coronoid fracture
Fracture fragment usually transverse and small (average 40% coronoid height)
 
Surgical Protocol for Terrible Triad §McKee MD et al JBJS March 2005 87-A
36 consecutive terrible triad injuries
Surgical Protocol: ORIF coronoid, ORIF or replace radial head, repair lateral structures, repair MCL or hinged ex-fix
15 excellent / 13 good / 7 fair / 1 poor
Concentric stability: 34
8 reoperations: 1 recurrent instability, 2 synostosis
 

Associated Injuries and Complications §Brachial Artery Disruption
<30 cases reported in the literature with closed injuries
Treatment:
Prompt surgical intervention: anteromedial approach and interpositional vein graft
§schemia >4 hr: fasciotomy
 

Neurologic Injury: Uncommon (up to 20%)
Ulnar (most often) : neuropraxia
Median / AIN: may occur with concomitant vascular disruption due to proximity  
 

Heterotopic Ossification
Soft tissue calcification (75%)
Anterior elbow and collaterals
Rarely limits motion
True Ectopic Calcification (5%)
Evident by 3-4 weeks
Brachialis region
Causes: delayed intervention, closed head injury, aggressive PROM
Resection: delayed until ossification appears mature; ~ 6 months after injury
 

DRUJ Injury
Essex Lopresti variant
Combined injury makes fixation of radial head more important
Valgus stability
Axial stability
May pin DRUJ in neutral