Focused examination of the thumb including CMC joint osteoarthritis, UCL injuries (gamekeeper's/skier's thumb), tendon injuries, and trigger thumb.
Thumb examination requires assessment of the three joints (CMC, MCP, IP), ligament stability (especially UCL), and tendon function. Examiners expect you to perform the thumb UCL stress test correctly, recognize CMC osteoarthritis patterns, and understand the significance of Stener lesion.
High-Yield Exam Summary
Joints:
Key Ligaments:
Tendons:
Stener Lesion:
CMC (Basal Joint) Osteoarthritis:
Demographics:
Symptoms:
Signs:
CMC osteoarthritis
Pain at CMC joint with crepitus
CMC osteoarthritis - bone-on-bone contact causes pain
Ability to detect true positives
Ability to exclude false positives
CMC joint assessment
Pain relieved with distraction
CMC joint pathology (OA, synovitis) - distraction unloads joint
Ability to detect true positives
Ability to exclude false positives
Observation:
Palpation:
Range of Motion:
Function:
Thumb UCL integrity
Greater than 30° of laxity OR greater than 15° difference from contralateral OR no firm endpoint
Complete UCL rupture requiring surgical repair
Ability to detect true positives
Ability to exclude false positives
UCL Testing Technique:
Extension Position:
30° Flexion:
Criteria for Complete Tear:
Always test both positions and compare sides!
Identify displaced UCL
Palpable mass (like a pea) at proximal aspect of MCP joint
Stener lesion - UCL has displaced superficial to adductor aponeurosis, requires surgery
Ability to detect true positives
Ability to exclude false positives
Radial collateral ligament integrity
Increased laxity compared to contralateral side
RCL injury (less common than UCL)
Ability to detect true positives
Ability to exclude false positives
EPL (Extensor Pollicis Longus):
EPB (Extensor Pollicis Brevis):
APL (Abductor Pollicis Longus):
FPL (Flexor Pollicis Longus):
FPB (Flexor Pollicis Brevis):
De Quervain's tenosynovitis (first compartment)
Sharp pain at radial styloid (first dorsal compartment)
De Quervain's tenosynovitis - stenosing tenosynovitis of APL and EPB
Ability to detect true positives
Ability to exclude false positives
De Quervain's tenosynovitis
Pain at first dorsal compartment
De Quervain's tenosynovitis (note: many false positives)
Ability to detect true positives
Ability to exclude false positives
Palpation:
Active Movement:
Classification (Quinnell):
| Grade | Description |
|---|---|
| 0 | Normal movement |
| I | Uneven movement |
| II | Actively correctable locking |
| III | Passively correctable locking |
| IV | Fixed locked position |
Pediatric Trigger Thumb:
| condition | location | test | keyFeature |
|---|---|---|---|
| CMC OA | Base of thumb | Grind test | Square hand, web space contracture |
| UCL Injury | Ulnar MCP | Valgus stress | Laxity greater than 30°, Stener lesion |
| De Quervain's | Radial styloid | Finkelstein's | First compartment tenderness |
| Trigger Thumb | A1 pulley (volar MCP) | Active flexion/extension | Clicking, nodule palpable |
| Bennett's Fracture | CMC joint | X-ray | Post-trauma, intra-articular fracture |
| Scaphoid Fracture | Snuffbox | Snuffbox tenderness | FOOSH, pain with thumb loading |
"24-year-old man fell while skiing 2 days ago and hit his thumb on the pole. He has pain and weakness gripping objects."
High-Yield Exam Summary