Mechanisms and Types of Injury: Fractures, Dislocations, Sprains, and Strains Practice Questions

25 multiple-choice questions on Mechanisms and types of injury: fractures, dislocations, sprains, and strains for paramedic and EMT students, from Chapter 38 (Orthopaedic Trauma). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A pedestrian's tibia is broken at the exact spot where a car bumper struck it. This is an example of injury by:

   1. A. Direct force
   2. B. Indirect force
   3. C. Twisting force
   4. D. Repetitive stress
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   Answer: A. Direct force

   Direct force breaks the bone at the point of impact. Indirect force travels along the limb and injures a distant site, such as a hip fracture from a knee striking the dashboard.

2. A driver's knee strikes the dashboard in a frontal crash. Because force is transmitted up the femur, you should also suspect injury to the:

   1. A. Ankle and foot
   2. B. Lumbar spine
   3. C. Hip and acetabulum
   4. D. Opposite shoulder girdle
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   Answer: C. Hip and acetabulum

   The knee-femur-hip pathway is a classic indirect-force mechanism; the femoral head can be driven out the back of the acetabulum. Ankle injuries come from the foot on the pedal, a separate mechanism.

3. Which feature makes a fracture an open fracture?

   1. A. Bone ends are visibly angulated
   2. B. A break in the overlying skin
   3. C. The bone breaks into many pieces
   4. D. The fracture enters a joint
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   Answer: B. A break in the overlying skin

   Any wound that communicates with the fracture site makes it open, even a small puncture from the inside. Angulation and comminution describe the fracture's shape, not whether it is open.

4. A 30-year-old skier has a lower leg fracture from a twisting fall. The x-ray will most likely show a fracture that is:

   1. A. Transverse
   2. B. Greenstick
   3. C. Spiral
   4. D. Impacted
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   Answer: C. Spiral

   Twisting forces create a spiral fracture that winds around the shaft. A transverse fracture runs straight across and usually results from a direct blow.

5. A fracture in which the bone is broken into three or more fragments is called:

   1. A. Oblique
   2. B. Comminuted
   3. C. Greenstick
   4. D. Transverse
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   Answer: B. Comminuted

   Comminuted fractures usually result from high-energy forces and are slow to heal. An oblique fracture is a single angled break with two fragments.

6. A fracture in which one bone end is driven into the other, often after a fall onto the hip or wrist, is called:

   1. A. Impacted
   2. B. Comminuted
   3. C. Avulsion
   4. D. Spiral
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   Answer: A. Impacted

   In an impacted fracture the fragments are jammed together, so the patient may still bear weight. That stability is deceptive and is why such fractures are missed.

7. A 72-year-old with metastatic breast cancer breaks her femur while turning in bed. This is best described as a:

   1. A. Stress fracture
   2. B. Avulsion fracture
   3. C. Greenstick fracture
   4. D. Pathologic fracture
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   Answer: D. Pathologic fracture

   A pathologic fracture occurs through bone weakened by disease, such as tumor or osteoporosis, with little or no force. A stress fracture results from repetitive loading of normal bone, not a single trivial event.

8. A 19-year-old military recruit has foot pain that worsens with marching after weeks of training. You suspect a:

   1. A. Pathologic fracture
   2. B. Comminuted fracture
   3. C. Stress fracture
   4. D. Greenstick fracture
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   Answer: C. Stress fracture

   Repeated loading causes microscopic cracks that outpace repair, commonly in the metatarsals and tibia. A pathologic fracture requires underlying bone disease, which this healthy recruit lacks.

9. A sudden, forceful muscle contraction pulls a tendon away with a fragment of bone. This is called:

   1. A. An impacted fracture
   2. B. An oblique fracture
   3. C. A pathologic fracture
   4. D. An avulsion fracture
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   Answer: D. An avulsion fracture

   The tendon or ligament is stronger than its bony attachment, so a chip of bone tears off; this is an avulsion fracture. An impacted fracture involves compression of fragments into each other, the opposite mechanism. An oblique fracture runs at an angle across the shaft from an angled or twisting force. A pathologic fracture occurs through bone already weakened by disease, such as a tumor or osteoporosis.

10. A greenstick fracture is most likely to occur in:

    1. A. Children
    2. B. Older adults
    3. C. Athletes
    4. D. Pregnant women
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    Answer: A. Children

    Children's bones are more flexible, so they bend and crack on one side like a green twig. Older adults have brittle bone that tends to break completely or be comminuted.

11. Which finding is most specific for a fracture rather than a sprain?

    1. A. Swelling at the site
    2. B. Crepitus at the site
    3. C. Pain on movement
    4. D. Bruising of the skin
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    Answer: B. Crepitus at the site

    The grating sensation of bone ends rubbing together indicates a fracture, though you should not try to elicit it. Swelling, pain, and bruising occur with both sprains and fractures.

12. The finding most characteristic of a dislocation is a joint that is:

    1. A. Swollen but fully mobile
    2. B. Locked in a deformed position
    3. C. Bruised without any deformity
    4. D. Painful only when palpated
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    Answer: B. Locked in a deformed position

    A dislocated joint is typically fixed out of position with marked deformity and loss of motion. A swollen joint that still moves through its full range points to a sprain or contusion rather than a dislocation.

13. A subluxation differs from a dislocation in that a subluxation is:

    1. A. Partial displacement of a joint
    2. B. A fracture next to the joint
    3. C. A complete ligament rupture
    4. D. A tear in the joint capsule
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    Answer: A. Partial displacement of a joint

    In a subluxation the joint surfaces remain partly in contact. A complete loss of contact is a dislocation.

14. A 19-year-old rolled her foot inward stepping off a curb. She has swelling and tenderness just in front of and below the lateral malleolus. The structure most likely injured is the:

    1. A. Achilles tendon
    2. B. Medial deltoid ligament
    3. C. Peroneus longus tendon sheath
    4. D. Anterior talofibular ligament
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    Answer: D. Anterior talofibular ligament

    Inversion sprains most often tear the anterior talofibular ligament, the weakest of the lateral ankle ligaments. The deltoid ligament is on the medial side and is injured by eversion, the tempting wrong choice.

15. A lineman received a high-voltage electrical shock and now holds his arm internally rotated and cannot turn it outward. Besides burns, you should suspect:

    1. A. An anterior shoulder dislocation
    2. B. Anterior elbow dislocation
    3. C. Posterior shoulder dislocation
    4. D. Acromioclavicular separation
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    Answer: C. Posterior shoulder dislocation

    Violent muscle contractions from electrical shock (or seizures) can dislocate the shoulder posteriorly, leaving the arm held in internal rotation and unable to rotate outward. These dislocations are often missed. Splint as found and transport. An anterior dislocation holds the arm slightly abducted and turned outward, an acromioclavicular separation causes a step at the top of the shoulder without locking rotation, and an elbow injury does not fix the shoulder in internal rotation.

16. A grade III (third-degree) sprain is best described as:

    1. A. Mild stretching without instability
    2. B. Partial tearing with some laxity
    3. C. Complete tearing of the ligament
    4. D. A fracture next to the ligament
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    Answer: C. Complete tearing of the ligament

    Grade I is stretching, grade II is partial tearing, and grade III is complete rupture with joint instability. Severe sprains can be as painful and disabling as fractures.

17. A patient's ankle is swollen and painful after a fall. Because sprains and fractures can look alike in the field, you should:

    1. A. Splint it as a possible fracture
    2. B. Have the patient walk to test it
    3. C. Wrap it and release the patient
    4. D. Apply heat to reduce stiffness
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    Answer: A. Splint it as a possible fracture

    Paramedics cannot reliably exclude a fracture without imaging, so treat any painful, swollen extremity as fractured. Testing by walking can displace a fracture and worsen injury.

18. A fall from a height onto both heels most commonly fractures the:

    1. A. Patellae
    2. B. Clavicles
    3. C. Fibulae
    4. D. Calcanei
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    Answer: D. Calcanei

    Axial load on the heels fractures the calcaneus, and the force continues up to the lumbar spine and hips. That is why calcaneal fractures prompt a search for spinal compression fractures.

19. A 24-year-old has a gunshot wound through the thigh. The thigh is deformed, and the entrance and exit wounds are small and barely bleeding. The fracture should be treated as:

    1. A. A closed fracture, as wounds are small
    2. B. An open fracture, likely comminuted
    3. C. A stable crack that needs no splint
    4. D. A soft-tissue wound until x-rayed
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    Answer: B. An open fracture, likely comminuted

    Any wound that communicates with a fracture makes it open, and a bullet that breaks a femur has, by definition, passed from the skin to the bone, carrying clothing and debris with it. The energy a bullet transfers usually shatters the bone into several fragments. Dress the wounds, splint the limb, check distal pulses and sensation (the femoral artery runs beside the shaft), give antibiotics if your protocol allows, and transport to a trauma center. Small skin wounds say nothing about the damage inside, so calling the fracture closed is the classic error. A deformed thigh is not a stable crack and must be splinted. Treating it as a soft-tissue wound until imaging delays splinting and infection prevention. (PHTLS 10th ed., ballistics and open fractures.)

20. A 26-year-old has a deep laceration over a deformed forearm with a bone end visible. This injury should be managed as:

    1. A. A closed fracture with a laceration
    2. B. An open fracture
    3. C. A dislocation
    4. D. A degloving injury of the forearm
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    Answer: B. An open fracture

    A wound with a visible bone end communicates with the fracture, making it open and at high risk of infection. Calling it closed because the bone retracted later is a common error. A deformed forearm with exposed bone is not a fracture that is still closed under a separate laceration, a dislocation, or a degloving injury; a wound that exposes bone at a fracture makes it open.

21. Which mechanism places a patient at greatest risk of an associated injury to the thoracic aorta or lungs?

    1. A. Clavicle fracture after a fall
    2. B. Wrist fracture after a fall
    3. C. Finger fracture after a fall
    4. D. Scapula fracture after a fall
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    Answer: D. Scapula fracture after a fall

    The scapula is protected by heavy muscle, so breaking it requires a great deal of force, which also injures the chest and great vessels. Clavicle fractures are common and usually result from lower energy.

22. The term angulation in a fracture refers to:

    1. A. Bone ends meeting at an angle
    2. B. The bone breaking into fragments
    3. C. The bone protruding through skin
    4. D. The bone being shortened
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    Answer: A. Bone ends meeting at an angle

    Angulation describes an abnormal angle between the fragments, which may compromise vessels and nerves. Protrusion through skin defines an open fracture, not angulation.

23. An overweight 12-year-old has had a limp and knee pain for 2 weeks with no injury. The knee looks normal. You should be concerned about a problem in the:

    1. A. Knee, a torn meniscus
    2. B. Thigh, a quadriceps strain
    3. C. Hip, a slipped epiphysis
    4. D. Lower back from bad posture
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    Answer: C. Hip, a slipped epiphysis

    Hip disorders often cause pain referred to the knee. Slipped capital femoral epiphysis, in which the femoral head slips at the growth plate, typically affects overweight adolescents and causes a limp with hip, thigh, or knee pain. The child should not bear weight and needs evaluation, because the slip can worsen. With no injury and a normal-looking knee, a meniscal tear or a muscle strain is unlikely, and posture does not explain a limp with knee pain.

24. Severe deformity of the knee with the lower leg displaced behind the femur after a high-speed crash most strongly suggests a:

    1. A. Patellar dislocation
    2. B. Knee dislocation
    3. C. Knee sprain
    4. D. Tibial stress fracture
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    Answer: B. Knee dislocation

    Displacement of the tibia relative to the femur is a true knee dislocation, a high-energy injury that threatens the popliteal artery. Patellar dislocation displaces only the kneecap, usually laterally, with a low-energy twist.

25. The bone most commonly fractured in children and also very common in adults falling onto the shoulder is the:

    1. A. Scapula
    2. B. Humerus
    3. C. Clavicle
    4. D. Acromion
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    Answer: C. Clavicle

    The slender clavicle transmits force from the arm to the trunk and breaks easily. The scapula is heavily padded by muscle and rarely fractures.