Orthopaedic Technologist Certified Cast Complications and Removal Questions and Answers — Questions and Answers
Question 1: A patient with a short leg cast for an ankle fracture complains of numbness and a "pins and needles" sensation on the top of their foot, along with difficulty lifting their toes toward their shin. Which underlying structure is MOST likely being compressed?
- Tibial nerve
- Sural nerve
- Peroneal nerve (Correct answer)
- Saphenous nerve
Correct answer: Peroneal nerve
The common peroneal nerve runs superficially around the neck of the fibula. A tight or poorly padded short leg cast can compress this nerve, leading to sensory deficits on the dorsum (top) of the foot and motor weakness of the ankle dorsiflexors, causing a condition known as "foot drop".
Question 2: Which of the following is the MOST significant factor contributing to thermal injury (burns) to the patient's skin during the application of a plaster cast?
- Using water that is too hot to dip the plaster (Correct answer)
- Applying fewer than 8 layers of plaster
- Molding the cast with the palms instead of the fingers
- Allowing the cast to air dry instead of using a fan
Correct answer: Using water that is too hot to dip the plaster
The chemical reaction between plaster of Paris and water is exothermic, meaning it releases heat as it cures. Using water with a temperature greater than 24°C (75°F) dramatically increases the peak temperature of this reaction, significantly raising the risk of causing a thermal burn to the patient's underlying skin.
Question 3: To minimize the risk of cutting or burning the patient's skin, what is the proper technique for using an oscillating cast saw?
- Dragging the blade along the cast in one continuous motion.
- Angling the blade at 45 degrees to the cast surface.
- Using a series of short, repeated "in-and-out" pressing motions. (Correct answer)
- Applying a lubricant to the blade before starting the cut.
Correct answer: Using a series of short, repeated "in-and-out" pressing motions.
An oscillating saw blade vibrates rapidly back and forth; it does not spin. The correct technique is to press the blade perpendicularly into the cast until it cuts through, then lift it and repeat this motion along the cut line. This "in-and-out" or "press-and-lift" method prevents heat buildup from friction and avoids dragging the blade across the skin, which could cause an abrasion or burn.
Question 4: A patient in a hip spica cast for a femur fracture develops severe, cramping abdominal pain, persistent nausea, and bilious vomiting several days after application. These symptoms are MOST indicative of which serious complication?
- Deep Vein Thrombosis (DVT)
- Compartment Syndrome
- Pulmonary Embolism
- Cast Syndrome (SMA Syndrome) (Correct answer)
Correct answer: Cast Syndrome (SMA Syndrome)
Cast syndrome, or Superior Mesenteric Artery (SMA) syndrome, is a rare complication where a large body or spica cast compresses the third portion of the duodenum between the SMA and the aorta. This creates a functional bowel obstruction, leading to symptoms of severe nausea, vomiting, and abdominal pain.
Question 5: When an Orthopaedic Technologist is instructed to bivalve a cast to relieve pressure, what is the correct procedure?
- Cutting a single small window over the area of pain.
- Making two complete longitudinal cuts on opposite sides of the cast. (Correct answer)
- Making one longitudinal cut and spreading the cast apart.
- Removing only the proximal half of the cast.
Correct answer: Making two complete longitudinal cuts on opposite sides of the cast.
Bivalving a cast means to cut it into two separate shells, typically an anterior and posterior half, by making two longitudinal cuts on opposite sides. This allows the cast to be spread or the top half to be removed completely, which fully relieves circumferential pressure while still allowing the bottom half to be used as a resting splint.
Question 6: Following the removal of a long arm cast that was in place for 8 weeks, which of the following is considered a normal and expected finding?
- Severe, pitting edema of the hand and fingers.
- Muscle atrophy and dry, scaly skin. (Correct answer)
- A foul odor with purulent drainage from the skin.
- Complete and immediate return to full range of motion.
Correct answer: Muscle atrophy and dry, scaly skin.
After prolonged immobilization, disuse muscle atrophy (a decrease in muscle size) is expected. The skin underneath the cast has not exfoliated normally, resulting in a buildup of dead skin cells that appears dry and flaky. These are common and expected findings that resolve with gentle cleaning, moisturizing, and gradual return to activity.
