June 20, 2024

The Unstable elbow is defined as the elbow joint becoming loose, losing alignment, and producing catch in motion.

Stabilizers of the elbow joint

Stabilizers in valgus and varus stress

Fortress concept

Elbow is like a fortress

Fortress concept

According to O’Driscoll

Outer wall stabilizers

  • Ulnohumeral articulations
  • Lateral Collateral Ligaments
  • Medial Collateral Ligamnets

Inner wall stabilizers

  • Radiohumeral articulations
  • Common extensors/ flexors muscles


Articulation involvedProximal radioulnar joint (Radial head)Ulnohumeral and radiohumeral jointBoth (diversion)
Direction of displacementAnterior and posteriorValgus/ Varus, Posterior, Medial, lateral, Posterolateral rotational instability (PLRI)Posterior
Degree of displacementSubluxationPerchedComplete
TimingAcute/ chronicAcute/ Chronic/ RecurrentAcute
Associated injuriesNoneRadial head, Olecranon, CoronoidNone

Patterns of the unstable elbow

  1. Valgus
    • Athletics chronic overuse injuries
    • Repetitive overload
      • Intrinsic (muscular)
      • Extrinsic ( external tensile overload)
  2. Varus
    • PLRI
    • Anterior Instability
    • Posterior Instability

A unified concept of elbow instability

Hori’s Cycle

Progress from lateral to medial side

[Three sequential stages of elbow instability]

May pass through soft tissue or bone or have both

Passes from [ 3 distinct stages], that can arrest anywhere depending upon severity of injured forces.

Stage ILCL disruptionPosterolateral rotatory subluxation (May undergo spontaneous reduction)
Stage IIAdditional anterior and posterior disruptionCoronoid perched over trochlea (May reduce with minimal force)
Stage III3 Parts
IIIAAnterior MCL intactStable in pronation
IIIBEntire MCL disruptedVarus, Valgus, and rotational instability following reduction
IIICEntire distal humerus devoid of soft tissue attachmentUnstable even in 90 degrees of flexion

The most common mechanism of injury producing unstable elbow: VALGUS STRAIN IN SUPINATED ELBOW

Investigations of the unstable elbow


  1. Plain Xray
  2. Stress radiograph
    • Valgus stress
    • Varus stress
    • Posterolateral stress
  3. MRI and MR arthrography
  4. CT arthrography: In undersurface tear in MCL (T-Sign)

Treatment of the unstable elbow

Surgical Options

  1. ORIF and repair of ligaments/tendons
  2. Excise unfixable radial head/ replace the radial head, repair ligaments/ tendons
  3. ORIF for coronoid and/or olecranon
  4. Type I/II coronoid :- Suture it
  5. Type III:-ORIF coronoid and apply hinged distractor

Recurrent dislocation of the radial head

Disruption of annular ligament produces anterior subluxation or dislocation of the radial head, especially during pronation

Treatment by annular ligament reconstruction and radial head excision

See also: Madelung Deformity

See also: Cubitus Valgus

See also: Cubitus Varus

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