BASE OF THUMB FRACTURES

Question 1

4 main types of thumb MC fractures

Answer 1

1. Extra-articular fractures
   - extra-articular epibasal fractures most common
2. Bennett fractures = partial articular
3. Rolando fractures = complete articular
4. Comminuted intra-articular fractures

Question 2

Mechanism of injury for base of thumb fractures

Answer 2

Axial load with thumb in flexion

Question 3

Deforming forces on extra-articular base of thumb fractures

Answer 3

• Proximal fragment pulled into extension by APL
• Distal fragment pulled into flexion by APB, FPB and adductor pollicis
• Results in apex dorsal angulation

Question 4

Indication for surgical management of extra-articular base of thumb fractures

Answer 4

> 30deg angulation

• affects thumb ROM and ability to grasp
• can lead to compensatory hyperextension deformity at MCPJ

Question 5

2 main surgical options for extra-articular base of thumb fractures

Answer 5

1. CRPP = K-wires in proximal fragment or trapezium and 2nd MC
2. ORIF with plate

Question 6

Pathoanatomy of Bennett fractures

Answer 6

2-part intra-articular fracture
Volar ulnar fragment remains attached to trapezium via Beak ligament
Deforming forces on shaft:
1. Dorsal and radial displacement by APL and EPB
2. Adduction and supination by adductor pollicis

Question 7

2 indications for surgical management of Bennett fractures

Answer 7

Most fractures need surgical management
1. Displacement with > 2mm articular incongruity
2. Joint subluxation
Joint reduction more important than restoration of articular congruity for outcome

Question 8

2 main surgical options for Bennett fractures

Answer 8

1. CRPP- K-wires into trapezium and 2nd MC

2. ORIF with screw if large volar ulnar fragment

Question 9

2 main complications with nonoperative management of base of thumb fractures

Answer 9

1. Malunion
   - can affect thumb ROM and grasp
   - requires corrective osteotomy
2. Early radiographic arthritis = doesn’t correlate with symptomatic arthritis

Question 10

Good and poor prognostic indicators for base of thumb fractures

Answer 10

Good prognostic factors:
1. Extra-articular fractures
2. Early treatment
Poor prognostic factors:
1. Intra-articular fractures
2. Delayed treatment

Question 11

Main radiographic views for thumb CMC joint

Answer 11

1. Roberts view = hyperpronation view with dorsum of thumb flat against cassette
2. Bett’s or Gedda’s view = hand in 30deg pronation