Complex Elbow Instability

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Definition

• Condition resulting from injury & resultant loss of function due to damage to the articular surface & ligamentous structures that stabilise the elbow
• May present as subluxation or incongruity with malalignment

Aetiology

Epidemiology

Anatomy

Contributions to Normal Stability

Static constraints

• Primary
  • Ulnohumeral articulation
  • Medial collateral ligament
  • Lateral collateral ligament
• Secondary
  • Radial head
  • Common flexor tendon
  • Common extensor tendon
  • Capsule

Dynamic constraints

• Muscles
  • that cross the elbow – providing compression
  • Especially
    • Triceps
    • Anconeus
    • Brachialis
• articular surfaces provide 50% of static stability & the ligaments/ capsule another 50%

• Articular Elements
  • Proximal part of the Ulnar
    • Major determinant of elbow stability is Ulnohumeral joint
    • Linear relationship between the amount of proximal ulna & stability with at least 30% of the articulation required (attachment of collaterals here)
  • Coronoid
    • At least 50% of the coronoid should be present for the ulnohumeral joint to be functional
  • Radial Head
    • Intimately related to the collateral ligaments
    • Role as secondary stabiliser in preventing valgus instability
      • Resistance to valgus stress is minimum when the MCL intact
      • However does prevent subluxation of joint if MCL deficient
    • Also secondary stabiliser to posterolateral instability of elbow
• Ligamentous Contributions
  • The collaterals are aided by the anterior capsule in preventing varus-valgus stress in full extension
  • LCL
    • The primary stabiliser is the ulnar part of the LCL (O’Driscoll)

Pathology

Disruption of circle of soft tissue or bone (Horii circle)

• begins on the lateral side of the elbow & progresses to the medial side in three stages
  • Stage 1 (PLRI)
    • Lateral collateral ligament is partially or completely disrupted
      • specifically the ulnar lateral collateral ligament that lies from ulna to lateral epicondyle posterior to the radial head
      • Results in posterolateral rotatory subluxation of the elbow which can reduce spontaneously (see below)
  • Stage 2 (perched ulna)
    • Additional disruption anterior & posterior
    • Incomplete posterolateral dislocation with subluxation/ dislocation of radial head & the medial edge of ulna resting on the trochlear (AP film) & coranoid perched on the trochlear (lateral film)
    • Dislocation reduced with minimal force
  • Stage 3 (dislocated)
    • Elbow dislocates & coranoid lies posterior to trochlear
  • 3A
    • All soft tissue sleeve including posterior part of medial collateral ligament disrupted (anterior medial collateral ligament intact)
    • Elbow pivots on intact AMCL
    • Reduction performed by recreating deformity with supination & valgus stress, followed by application of traction, varus stress, & pronation simultaneously
    • AMCL provides stability if forearm remains pronated
  • 3B
    • Entire MCL (including AMCL) disrupted
    • Varus, valgus & rotatory instability all present following reduction
    • Immobilise in cast 90 flexion
  • 3C
    • Soft tissues stripped off entire distal humerus (including the flexor-pronator & common extensor origins)
    • Grossly unstable even in flexion (need to flex > 90)

Classification

Terrible Triad injury

• Elbow dislocation
• Fracture radial head
• Fracture coranoid process

History

Examination

• Assess instability by putting elbow through gentle ROM
  • 1.If elbow appears to subluxate or dislocate, a splint is applied AP & lateral XRs show reduction splint or sling re-evaluate at 5-7 days
  • 2.If elbow subluxates or dislocates with extension or XRs show incongruence of joint surfaces pronate forearm & reassess stability if stable then hinged brace or cast brace in full pronation (extension block of 30 sometimes necessary)
  • 3.If extension block of > 30-45 needed to maintain reduction then consider surgical repair
• Stress radiographs should be taken
• Sometimes need to evaluate instability in OT under GA
  • Best with arm in overhead position
  • Test for valgus, varus & posterolateral rotatory instability
  • (Valgus stress test in full pronation so not confuse with PLRI)
• Test in full extension then 30 flexion
• Lateral pivot shift
  • Arm overhead & extended
  • Supinate & valgus stress then flex causing maximum posterolateral subluxation at ~ 40 flexion (patient apprehensive)
  • Clunk of reduction with further flexion

Investigations

Differential Diagnosis

Treatment

Posterolateral Rotatory Instability

• Pathology
  • Follows injury to the ulnar part of the LCL (varus extension stress)
  • Allows transient rotatory subluxation of the ulnohumeral joint & secondary subluxation or dislocation of the radiohumeral joint
  • Annular ligament intact thus the proximal radius & ulnar move as one
• Clinical features
  • Recurrent painful clicking/ snapping/ clunking or locking of elbow
  • Occurs in extension 1/2 of arc with elbow in supination
  • Trauma or surgery history usually present
  • Radial head excision or Tennis elbow surgery often mentioned
• Lateral Pivot Shift Test (O‘Driscoll)
  • Flexion of the elbow from extended position & supination of the forearm with valgus & axial load
  • In posterolateral instability the radial head subluxes or dislocates posteriorly with rotatory subluxation of the ulnohumeral joint & palpably reduces at or just beyond 40 of flexion
• Radiographic Features
  • Normal or slight widening of radiohumeral joint on AP XR
  • Radial head posterior to capitellum on lateral XR (esp with supination)
  • Fluoroscopy of pivot shift test will often reveal subluxation
• Treatment
  • Often reconstruction required if symptomatic
  • Tends not to become stable except possibly in the very early stages
• Technique
  • Kocher approach
  • The common extensor origin elevated to reveal origin of LCL on the lateral epicondyle
  • Distally anconeus reflected posteriorly & ECU anteriorly
  • Supinator crest of Ulna identified
  • Capsulotomy & inspection of joint
  • Anterior & posterior capsule plicated
  • If able to reattach the LCL then performed
  • If not then reconstructed with palmaris longus graft
  • Isometric point located on the epicondyle & then fixed
  • All sutures tied with the elbow flexed 30 & pronated
• Post op
  • Cast for 4 weeks in elbow flexion of 90 & full pronation
  • Then hinged splint with 30 extension stop for 6 weeks
  • Then free splint for further 4-6 weeks
  • Normal activity at 6 months

Fracture of Olecranon

• Type III fracture has ligamentous disruption
• If minimally comminuted then plate fixation stabilises the ulnohumeral joint (mandatory if fracture line in anterior half of notch)
• If coronoid involved then must be reduced & rigidly fixed

Fracture of Coronoid

• Most important part of the ulnohumeral articulation
• Resists posterior displacement of the ulna
• Classification
  • Reagan & Morrey
  • Type 1
    • Small chip off tip & indicator of elbow dislocation and/or collateral ligament injury
    • Stable & early mobilisation
  • Type 2
    • Up to 50% of coronoid elbow may be unstable
    • If EUA has subluxation in less than 40-45 of flexion then need to stabilise
    • If large enough then screw fixation performed
    • If too small for screw then heavy braided sutures used (passed over coronoid fragment & tied through ulna)
    • If still unstable then elbow distraction device used (eg. Compass Hinge)
  • Type 3
    • Greater than 50%
    • Grossly unstable ulnohumeral joint
    • Fix with screw & distraction neutralisation device
    • If severely comminuted then realign with heavy suture & distraction device applied

Fracture of Radial Head & Coronoid with Dislocation

• Terrible triad
• Radial head replaced or fixed & coronoid fixed
• Protected with distractor
  • Allows motion but eliminates the forces

Fracture of Radial Head with Attenuation or Tear of MCL

• 1-2% of patients with radial head fracture
• Classification of radial head fractures
  • Mason (1954) three types
    • Type I undisplaced
    • Type II displaced wedge fragments
    • Type III comminuted
    • Type IV radial head fracture associated with elbow dislocation
      • Added by Johnson
• Principles of treatment
  • Aim to retain the radial head as the secondary stabiliser to valgus stress by osteosynthesis
  • If able to reconstruct then
    • Stable arc within 40 of extension unrestricted motion after 2 weeks
    • Dislocates with 60 of extension immobilise for 2 weeks then motion in hinged elbow splint with 30 extension stop for 2 weeks
    • MCL not repaired
• Prerequisites for excision of fragment of radial head
  • Excised fragment < 1/3 of radial head
  • Excised fragment does not articulate with lesser sigmoid notch of ulna (ie anterolateral 1/3 of radial head this is also the site where fixation can be placed without impingement against the ulna during forearm rotation)
• If not able to reconstruct the radial head then
  • Use of prosthesis or allograft
• Repair of the MCL acutely may be avulsed directly from the medial epicondyle requiring reattachment but if midsubstance then attachment more difficult
• Followed by locked hinged brace for 4 weeks then unlocked & motion in stable arc
• Total of 6 weeks

Fracture of Radial Head with Dislocated elbow

• Mason IV injury
• If coronoid intact then reduce & assess the stability of the ulnohumeral joint
• Additional treatment according to fracture type
• Principles of treatment
  • Type 1 (undisplaced)
    • If arc of motion stable to 45-50 then place in splint with 60 extension stop for 10 days
    • Full extension allowed in hinged splint for protection
  • Type 2 (displaced)
    • Need ORIF
    • Will result in instability if radial head resected
    • Usually not necessary to repair the MCL repair only if unstable arc of motion
  • Type 3 (comminuted)
    • Most difficult to treat
      • If not able to reconstruct the radial head then excise & repair the collateral ligaments
      • If still unstable then use of implant
      • If still unstable then External Fixator allowing flexion an option (Compass Hinge from S & N)
        • Allows distraction to maintain alignment but ROM allowed
        • Removed at 3-4 weeks & splint used then

Chronic Elbow Instability

• Most activities only need 30-130 (100 arc) flexion-extension
• And 100 pronation-supination (50 each)
• Prerequisites for elbow stability
  • Normal articular congruence
  • Anterior band of MCL
  • Ulnar part of LCL
  • Annular ligament
• Resistance to valgus stress by radial head minimal when MCL intact
• Attenuated or torn ulnar part of LCL can cause PLRI with or without radial head

Chronic Non-Reduced Dislocation

• Normally 3rd world
• Secondary to fracture causing instability
• Operation indicated if painful
• Use external fixation distraction device

Recurrent Dislocation

• Rare
• LCL (PLRI) >> MCL
• 25% have lateral epicondyle nonunion
• LCL laxity most common
• MCL is unlikely to be lax

Posterolateral Rotatory Instability

• Secondary to LCL laxity
• Acute LCL tear after dislocation
• Tennis Elbow Release
• Describe clunk on flexion/ extension
• Posterolateral pain
• O’Driscoll Lateral Pivot Shift Test
• Treatment PLRI
  • Kocher approach
  • Drill holes x 2 base Tubercle of Crista Supinatoris
  • Drill holes x 2 at Lateral Epicondyle
  • Palmaris graft in figure of “8”
  • Nestor 90% success
• MCL Deficiency

• Throwing injury

• Examination
  • Valgus stress
  • 40% Ulna nerve symptoms
  • 40% Calcification MCL
  • Pain at anterior bundle MCL on palpation
• Investigations
  • Stress view
  • Abnormal cf. opposite side if > 3mm difference
• Management
  • Reconstruct with palmaris longus with two-strand technique

Complications

Prognosis

References