Focused examination for elbow instability including posterolateral rotatory instability (PLRI), valgus instability (MCL), and assessment of chronic instability patterns.
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.
High-Yield Exam Summary
Primary Stabilizers:
Secondary Stabilizers:
MCL Complex:
LCL Complex:
Posterolateral Rotatory Instability (PLRI):
Posterolateral Rotatory Instability:
History:
Mechanism:
Key Feature:
Diagnose PLRI
Apprehension, clunk, or visible subluxation/reduction of radial head as elbow flexes past 40°
PLRI - LUCL deficiency with posterolateral subluxation of radial head
Ability to detect true positives
Ability to exclude false positives
Lateral Pivot Shift Interpretation:
PLRI assessment
Increased posterolateral translation of radial head compared to contralateral side
LUCL insufficiency (PLRI)
Ability to detect true positives
Ability to exclude false positives
Functional test for PLRI
Apprehension, pain, or inability to push up with arms supinated (improves with pronation)
PLRI - patient avoids supinated push-up due to instability
Ability to detect true positives
Ability to exclude false positives
Functional PLRI assessment
Apprehension, clunking, or inability to complete push-up with supinated hands
PLRI - supinated position allows posterolateral subluxation
Ability to detect true positives
Ability to exclude false positives
MCL integrity
Increased valgus laxity, pain at medial elbow, or endpoint softness
MCL injury (anterior bundle if positive at 30° flexion)
Ability to detect true positives
Ability to exclude false positives
Why Test at 30° Flexion:
MCL injury in throwers
Maximum pain reproduced at 70-120° flexion (shear zone)
MCL injury - high sensitivity in throwing athletes
Ability to detect true positives
Ability to exclude false positives
MCL integrity
Medial elbow pain or apprehension
MCL injury (particularly posterior bundle)
Ability to detect true positives
Ability to exclude false positives
PLRI Assessment:
MCL Assessment:
Posterior Stability:
Three Components:
Examination Findings:
Important:
| pattern | mechanism | structure | test | presentation |
|---|---|---|---|---|
| PLRI (Lateral) | Supination, valgus, axial load | LUCL | Pivot shift, chair push-up | Giving way with extension |
| Valgus (Medial) | Valgus stress (throwing) | MCL anterior bundle | Valgus stress 30°, moving valgus | Medial pain, throwing athlete |
| Posterior | Direct blow, hyperextension | Olecranon, triceps | Posterior drawer | Rare isolated |
| Multidirectional | High-energy trauma | Multiple (terrible triad) | All directions unstable | Severe injury, usually acute |
| condition | location | mechanism | keyTest | xray |
|---|---|---|---|---|
| PLRI | Lateral | Prior dislocation | Pivot shift, supinated push-up | May be normal |
| MCL Injury | Medial | Valgus/throwing | Valgus stress 30° | May show calcification |
| Lateral Epicondylitis | Lateral | Overuse | Resisted wrist extension | Normal |
| Snapping Triceps | Posterior/Medial | Flexion-extension | Palpable snap over epicondyle | May show variant anatomy |
| Ulnar Nerve Subluxation | Medial | Flexion | Palpable subluxation | Normal |
"32-year-old man with history of elbow dislocation 6 months ago, now experiencing his elbow 'giving way' when pushing up from a chair."
High-Yield Exam Summary