OTC Orthopaedic Technologist Certified Upper Extremity Casting 3 — Questions and Answers
Question 1: A thumb spica cast immobilizes the thumb and wrist but leaves which joints free?
- The interphalangeal (IP) joint of the thumb (Correct answer)
- The metacarpophalangeal (MCP) joint of the thumb
- The index finger MCP joints
- The wrist radiocarpal joint
Correct answer: The interphalangeal (IP) joint of the thumb
A standard thumb spica cast immobilizes the wrist and the thumb MCP joint but leaves the thumb IP joint free for movement.
Question 2: Which condition is the most common indication for a thumb spica cast?
- Colles' fracture
- Scaphoid fracture (Correct answer)
- Bennett's fracture-dislocation
- Hamate hook fracture
Correct answer: Scaphoid fracture
Scaphoid fractures are among the most common indications for thumb spica casting because the scaphoid's blood supply requires prolonged immobilization.
Question 3: To prevent a Volkmann's ischemic contracture, which neurovascular check is most critical in the first hours after upper extremity casting?
- Sensation in the radial nerve distribution over the dorsum of the hand
- Capillary refill time and skin color in the fingertips (Correct answer)
- Grip strength assessment
- Shoulder range of motion
Correct answer: Capillary refill time and skin color in the fingertips
Capillary refill and fingertip color are early, reliable indicators of vascular compromise that precedes Volkmann's contracture.
Question 4: Cast saw injuries most commonly occur because patients do not understand that the blade moves in what type of motion?
- Rotary (spinning) motion
- Oscillating (back-and-forth) motion (Correct answer)
- Reciprocating (up-and-down) motion
- Continuous linear motion
Correct answer: Oscillating (back-and-forth) motion
The cast saw blade oscillates rather than spins, which cuts hard cast material without cutting skin when used correctly, but patients fear it cuts like a circular saw.
Question 5: When splitting a cast bivalve style, what is the correct sequence of steps?
- Cut both sides, spread cast, cut padding and stockinette (Correct answer)
- Cut one side only, apply bivalve brace
- Remove cast entirely, reapply as splint
- Cut top half only, leave bottom as posterior shell
Correct answer: Cut both sides, spread cast, cut padding and stockinette
Bivalving requires cutting both medial and lateral sides, spreading the cast, then cutting the underlying padding and stockinette to fully relieve pressure.
Question 6: What is the primary advantage of fiberglass casting material over plaster of Paris?
- Lower cost
- Lighter weight and greater strength-to-weight ratio (Correct answer)
- Easier to mold for complex fractures
- Less risk of thermal burns
Correct answer: Lighter weight and greater strength-to-weight ratio
Fiberglass casts are significantly lighter and stronger per unit weight than plaster, improving patient comfort and durability.
Question 7: A patient with a freshly applied long arm cast develops pain that worsens with passive extension of the fingers. This most likely indicates:
- Normal post-casting discomfort
- Developing compartment syndrome (Correct answer)
- Cast too loose requiring reinforcement
- Radial nerve palsy
Correct answer: Developing compartment syndrome
Pain with passive stretch of the muscles in a casted compartment is a hallmark sign of developing compartment syndrome and requires immediate evaluation.
OTC Orthopaedic Technologist Certified Upper Extremity Casting 3
A thumb spica cast immobilizes the thumb and wrist but leaves which joints free?