3.3 Musculoskeletal Injuries
Key Takeaways
- Open fractures (bone protruding through skin) carry a high risk of infection and require sterile dressing over the wound before splinting
- Closed fractures present with pain, swelling, deformity, crepitus, false motion, and inability to bear weight or use the extremity
- The cardinal rule of splinting is to immobilize the joint above AND the joint below the fracture site
- PMS (Pulse, Motor function, Sensation) must be checked distal to the injury BEFORE and AFTER splinting to detect neurovascular compromise
- Traction splints are indicated ONLY for isolated midshaft femur fractures and are contraindicated for fractures near the knee or hip, pelvic fractures, and partial amputations
- Compartment syndrome occurs when swelling within a closed fascial compartment compromises circulation; the hallmark symptom is pain out of proportion to the injury that worsens with passive stretch
- Dislocations present with deformity, locked joint position, and loss of normal range of motion; do NOT attempt to reduce (relocate) a dislocation in the field
Musculoskeletal injuries include fractures, dislocations, sprains, and strains. They are rarely the immediate cause of death, but they can produce major blood loss, lasting disability, and severe pain. A closed femur fracture can lose 1-2 liters of blood into the thigh, and a pelvic fracture can lose enough blood to cause fatal shock. Proper splinting and repeated neurovascular checks are core EMT skills the NREMT tests heavily.
Fractures: Open vs. Closed
Closed Fracture: the bone is broken but the skin is intact. Signs include pain, swelling, deformity, crepitus (a grating sensation), false motion, guarding, ecchymosis, and inability to bear weight. Significant internal bleeding can collect at the fracture site.
Open Fracture: bone has broken through the skin or an external wound communicates with the fracture, creating a high risk of contamination and infection. Cover the exposed bone and wound with a moist sterile dressing, then splint. Do not push protruding bone back under the skin and do not intentionally pull bone ends into the wound. The mnemonic DOTS (Deformity, Open wounds, Tenderness, Swelling) and CSM (Circulation, Sensation, Motion) guide the focused extremity exam.
Dislocations
A dislocation is displacement of a bone from its normal joint position. It presents with marked deformity, a locked joint, and loss of normal range of motion. Common sites are the shoulder, elbow, finger, hip, knee, and patella. At the EMT level, do not attempt to reduce (relocate) a dislocation in the field. Splint it in the position found, and monitor distal PMS (Pulse, Motor, Sensation), because a dislocated knee or elbow can compromise the artery and nerve crossing the joint.
Sprains vs. Strains
| Feature | Sprain | Strain |
|---|---|---|
| Structure injured | Ligament (bone to bone) | Muscle or tendon (muscle to bone) |
| Mechanism | Joint forced past normal range | Overstretch or overexertion |
| Presentation | Swelling, bruising, joint instability | Pain, spasm, weakness |
| Common sites | Ankle, knee, wrist | Back, hamstring, shoulder |
Field care for both is the same supportive approach captured by RICE: Rest, Ice (with a skin barrier), Compression, and Elevation, plus splinting if pain is significant.
Splinting Principles
- Assess distal PMS before splinting to establish a baseline.
- Remove or cut away clothing and jewelry from the injured area (swelling can trap rings).
- Cover open wounds with a sterile dressing first.
- Immobilize the joint above and the joint below the fracture - the cardinal rule of splinting. For a joint injury, immobilize the bone above and below instead.
- Pad all voids and bony prominences.
- Splint in the position found unless there is no distal pulse, in which case apply gentle in-line traction to attempt to restore circulation per protocol.
- Reassess PMS after splinting; if PMS is lost, loosen and reposition.
- Apply cold packs (with a barrier) and elevate when possible.
Types of Splints
- Rigid splints (board, cardboard, SAM splint, padded boards): best for long-bone fractures; must be padded and secured.
- Soft/formable splints (pillow, sling and swathe, blanket roll, vacuum splint): conform to the limb; good for ankle, wrist, and shoulder injuries.
- Traction splints (Hare, Sager): apply longitudinal pull to realign a femur shaft, reducing pain, muscle spasm, and internal bleeding.
Traction Splint: Indications and Contraindications
Indications: an isolated midshaft femur fracture, typically with a shortened, externally rotated leg and thigh pain/swelling.
Contraindications: fracture near or involving the knee or hip, pelvic fracture, partial amputation or avulsion with bone separation, and lower-leg or ankle injury on the same extremity. Applying traction across these injuries can worsen damage.
Application sequence: assess distal PMS; apply manual stabilization and gentle manual traction; place the ankle hitch; position the splint; apply mechanical traction until the injured leg matches the length of the uninjured leg or pain eases; secure support straps; reassess distal PMS.
Compartment Syndrome
Compartment syndrome is a limb-threatening rise in pressure within a closed fascial compartment, usually from swelling after a fracture or crush injury, or from a splint applied too tightly. The hallmark is pain out of proportion to the injury that worsens with passive stretch of the muscles in that compartment. The classic 6 P's are Pain, Pressure, Paresthesia, Paralysis, Pallor, and Pulselessness - but pulselessness is a very late finding, so never wait for an absent pulse to act.
EMT management is to remove constricting bandages or splints, keep the limb at heart level (not elevated, which can lower perfusion), and transport promptly because definitive treatment is a surgical fasciotomy.
Crush Injury and Crush Syndrome
A prolonged crush (a limb pinned for hours, or under collapsed debris) can release potassium and myoglobin when the weight is removed, causing dysrhythmias and kidney injury (crush syndrome). Coordinate with ALS before extricating a long-entrapped patient, and transport rapidly.
Pelvic Fractures: A Hidden Killer
Unlike most isolated extremity fractures, a pelvic fracture can be immediately life-threatening because the pelvis surrounds large veins and arteries; a disrupted pelvis can bleed several liters into the retroperitoneal space with little external sign. Suspect a pelvic fracture after a high-energy mechanism (fall from height, motorcycle crash, pedestrian struck) when there is pelvic pain, instability, or signs of shock. Do not "spring" or repeatedly rock the pelvis to test stability - this can dislodge clots and worsen bleeding.
Apply a commercial pelvic binder (or a folded sheet) centered over the greater trochanters, treat for shock, handle the patient gently, and transport rapidly.
Special Splinting Scenarios and Common Errors
Several recurring NREMT scenarios test judgment rather than rote steps. If a long-bone fracture has no distal pulse, the priority is to attempt gentle realignment with in-line traction to restore circulation, because a pulseless limb threatens viability. If a patient has an angulated fracture with a good distal pulse, splint it as found. After splinting, if the patient suddenly loses sensation or pulse, the splint is too tight - loosen and reposition, then reassess, rather than continuing transport.
A frequent error is forgetting to remove rings, watches, and bracelets before swelling traps them and cuts off circulation. Another is splinting without reassessing PMS, which leaves a developing neurovascular injury undetected. Finally, remember that severe musculoskeletal injuries are rarely the patient's most life-threatening problem in multisystem trauma - airway, breathing, and major hemorrhage always come first, and definitive fracture care can wait until those are addressed. Manage pain, prevent further injury, and keep the patient warm to support clotting and comfort during transport.
When splinting a fracture of the tibia (lower leg), the EMT should immobilize:
Traction splints are indicated for which of the following injuries?
After applying a splint to a patient's forearm, the EMT notes that the patient can no longer feel their fingers. The EMT should:
The hallmark symptom of compartment syndrome is:
An EMT finds a patient with an open fracture of the humerus. Bone is visible through the wound. The MOST appropriate initial management is to:
Arrange the steps for proper splint application in the correct order:
Arrange the items in the correct order