Elbow Instability Examination
Elbow instability examination requires understanding the different instability patterns and their associated structures. Examiners expect you to differentiate posterolateral rotatory instability (PLRI - lateral collateral ligament complex injury) from valgus instability (MCL injury), and understand the "terrible triad" injury pattern.
Quick Reference One-Pager
Lateral (PLRI)
- LUCL is key stabilizer
- Pivot shift test
- Posterolateral drawer
- Chair push-up test
- Supination with valgus stress
Medial (MCL)
- Anterior bundle most important
- Valgus stress at 30° flexion
- Moving valgus stress test
- Milking maneuver
- Common in throwers
Posterior
- Olecranon tip palpation
- Triceps integrity
- Posterior drawer
- Rare in isolation
Key Points
- Compare with contralateral side
- Examine supine with arm above head
- PLRI most common chronic instability
- MCL injury in overhead athletes
Anatomy and Stabilizers
Elbow Stability
Primary Stabilizers:
- Ulnohumeral articulation (bony stability)
- Anterior MCL bundle (valgus stability)
- Lateral ulnar collateral ligament (LUCL) (rotatory stability)
Secondary Stabilizers:
- Radial head
- Common extensor origin
- Common flexor origin
- Capsule
MCL Complex:
- Anterior bundle: Primary valgus restraint (taut in extension)
- Posterior bundle: Secondary restraint (taut in flexion)
- Transverse ligament: No significant role
LCL Complex:
- LUCL: Most important for PLRI prevention
- Radial collateral ligament (RCL)
- Annular ligament
- Accessory LCL
Posterolateral Rotatory Instability (PLRI):
- Most common chronic elbow instability pattern
- Caused by LUCL injury (usually from dislocation)
- Radius and ulna rotate externally and subluxate posterolaterally
- Patient reports elbow "giving way" with arm extended
Clinical Presentation
Posterolateral Rotatory Instability:
History:
- Previous elbow dislocation (often "reduced spontaneously")
- Elbow "gives way" or "clicks" with arm extended
- Difficulty pushing up from chair with arms
- May have recurrent subluxations
Mechanism:
- Fall on outstretched hand
- Elbow dislocation with LUCL avulsion
- Iatrogenic (lateral epicondyle surgery)
Key Feature:
- Instability occurs with forearm supination, elbow extension, and axial/valgus load
Provocative Tests - PLRI
Special test
Lateral Pivot Shift Test (Posterolateral Rotatory Drawer)
Diagnose PLRI
Technique
- 1Patient supine, arm overhead, elbow extended
- 2Examiner holds wrist and elbow
- 3Apply axial compression, valgus stress, and forearm supination
- 4Flex elbow from extension while maintaining forces
Positive Sign
Apprehension, clunk, or visible subluxation/reduction of radial head as elbow flexes past 40°
Indicates
PLRI - LUCL deficiency with posterolateral subluxation of radial head
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Lateral Pivot Shift Interpretation:
- Often difficult to elicit in awake patients (guarding)
- May need to perform under anesthesia for definitive diagnosis
- Reduction "clunk" occurs at approximately 40° flexion
- Supination is critical - pronation stabilizes the joint
Special test
Posterolateral Rotatory Drawer Test
PLRI assessment
Technique
- 1Patient supine, elbow flexed to 40-90°
- 2Forearm in neutral or slight supination
- 3Apply posterolateral force to proximal radius and ulna
- 4Observe for posterolateral translation
Positive Sign
Increased posterolateral translation of radial head compared to contralateral side
Indicates
LUCL insufficiency (PLRI)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Chair Push-Up Test (Table-Top Relocation)
Functional test for PLRI
Technique
- 1Patient pushes up from chair arms with forearms supinated
- 2Arms at sides, elbows extended
- 3Observe for symptoms
Positive Sign
Apprehension, pain, or inability to push up with arms supinated (improves with pronation)
Indicates
PLRI - patient avoids supinated push-up due to instability
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Floor Push-Up Test
Functional PLRI assessment
Technique
- 1Patient performs push-up with hands in maximum supination
- 2Observe for symptoms or avoidance
Positive Sign
Apprehension, clunking, or inability to complete push-up with supinated hands
Indicates
PLRI - supinated position allows posterolateral subluxation
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Provocative Tests - MCL (Valgus Instability)
Special test
Valgus Stress Test
MCL integrity
Technique
- 1Patient supine or seated, elbow at 30° flexion
- 2Stabilize humerus with one hand
- 3Apply valgus stress to forearm with other hand
- 4Palpate MCL for gapping and pain
Positive Sign
Increased valgus laxity, pain at medial elbow, or endpoint softness
Indicates
MCL injury (anterior bundle if positive at 30° flexion)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Why Test at 30° Flexion:
- At 30°, posterior capsule is relaxed
- Isolated MCL stress (not confounded by posterior capsule)
- Anterior bundle of MCL is primary restraint
- Compare with contralateral side for laxity
Special test
Moving Valgus Stress Test
MCL injury in throwers
Technique
- 1Patient supine, shoulder abducted 90°
- 2Start with elbow fully flexed
- 3Apply constant valgus torque
- 4Extend elbow quickly from 120° to 30°
Positive Sign
Maximum pain reproduced at 70-120° flexion (shear zone)
Indicates
MCL injury - high sensitivity in throwing athletes
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Milking Maneuver
MCL integrity
Technique
- 1Patient's elbow flexed beyond 90°
- 2Patient or examiner grasps thumb of affected arm
- 3Pull thumb creating valgus stress on flexed elbow
Positive Sign
Medial elbow pain or apprehension
Indicates
MCL injury (particularly posterior bundle)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Additional Assessment
Associated Findings
PLRI Assessment:
- Radial head tenderness (associated fracture)
- Lateral epicondyle tenderness (extensor origin)
- Ulnar nerve symptoms (subluxation over medial epicondyle)
MCL Assessment:
- Ulnar nerve symptoms (runs behind medial epicondyle)
- Flexor mass tenderness
- Cubital tunnel assessment
Posterior Stability:
- Olecranon fracture (posterior instability)
- Triceps integrity
- Posterior drawer (rare isolated finding)
Terrible Triad Assessment
Three Components:
- Elbow dislocation
- Radial head fracture
- Coronoid fracture
Examination Findings:
- Significant swelling
- Limited ROM
- Potential instability in all directions
- May have crepitus (fracture)
Important:
- Usually assessed post-reduction
- May require examination under anesthesia
- High risk of recurrent instability without surgical repair
Instability Patterns
- mechanism
- Supination, valgus, axial load
- structure
- LUCL
- test
- Pivot shift, chair push-up
- presentation
- Giving way with extension
- mechanism
- Valgus stress (throwing)
- structure
- MCL anterior bundle
- test
- Valgus stress 30°, moving valgus
- presentation
- Medial pain, throwing athlete
- mechanism
- Direct blow, hyperextension
- structure
- Olecranon, triceps
- test
- Posterior drawer
- presentation
- Rare isolated
- mechanism
- High-energy trauma
- structure
- Multiple (terrible triad)
- test
- All directions unstable
- presentation
- Severe injury, usually acute
Differential Diagnosis
- location
- Lateral
- mechanism
- Prior dislocation
- keyTest
- Pivot shift, supinated push-up
- xray
- May be normal
- location
- Medial
- mechanism
- Valgus/throwing
- keyTest
- Valgus stress 30°
- xray
- May show calcification
- location
- Lateral
- mechanism
- Overuse
- keyTest
- Resisted wrist extension
- xray
- Normal
- location
- Posterior/Medial
- mechanism
- Flexion-extension
- keyTest
- Palpable snap over epicondyle
- xray
- May show variant anatomy
- location
- Medial
- mechanism
- Flexion
- keyTest
- Palpable subluxation
- xray
- Normal
Summary Presentation
“32-year-old man with history of elbow dislocation 6 months ago, now experiencing his elbow 'giving way' when pushing up from a chair.”
Examiner Tips
Do
- Understand LUCL anatomy and PLRI mechanism
- Perform pivot shift test correctly (supination + valgus + axial load)
- Use chair push-up as practical functional test
- Compare with contralateral elbow
- Test MCL at 30° flexion (isolates ligament)
Don't
- Miss subtle apprehension (often no frank clunk awake)
- Forget pronation stabilizes PLRI
- Omit neurovascular assessment
- Miss terrible triad components post-dislocation
- Forget to assess for snapping triceps/ulnar nerve