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Extremity Trauma

Category: Trauma Sources: raw/protocols/nm-sop-guidelines-treatment-2022.pdf Last updated: 2026-04-05

Overview

Extremity trauma includes fractures, dislocations, soft tissue injuries, and vascular injuries to the arms and legs. While rarely the immediate cause of death, extremity injuries can contribute to hemorrhagic shock through occult blood loss, cause permanent disability through compartment syndrome or neurovascular compromise, and distract from more critical injuries in the multisystem trauma patient. The primary goal is hemorrhage control, neurovascular assessment, and immobilization — in that order.

Mechanism

Why Splinting Works

Immobilizing a fracture accomplishes three things simultaneously, and understanding each one explains why splinting is not optional:

  1. Reduces pain — Bone ends grinding against each other with every movement generate severe pain. Immobilizing the fracture ends reduces this movement and lowers the pain stimulus, which also reduces catecholamine surge and its effect on heart rate and pressure.

  2. Reduces hemorrhage — Muscle surrounding a fracture can tamponade (compress) bleeding vessels when the muscle mass is kept in position. Movement disrupts this tamponade, reopens lacerated vessels, and forces blood out of the tissue into expanding hematoma. Additionally, sharp bone ends lacerate muscle and vessels with every movement. A splinted limb loses significantly less blood than one that is repeatedly moved.

  3. Prevents neurovascular injury — The nerves and vessels that run alongside long bones are at risk every time a bone end moves. A femur fracture in a patient who is moved without splinting can lacerate the femoral artery or damage the femoral nerve with a single repositioning. Immobilization prevents this.

Closed Long Bone Hemorrhage Estimates

Closed fractures bleed internally into surrounding soft tissue. The amounts are clinically significant:

Bone Estimated Blood Loss
Femur (mid-shaft) 1,000–2,000 mL (1–2 L)
Tibia / fibula 500 mL–1 L
Humerus up to 500 mL

A patient with bilateral femur fractures from a high-speed MVC has the potential for 2–4 L of internal blood loss from the fractures alone — in addition to any intrathoracic, intraabdominal, or pelvic hemorrhage. This patient is in hemorrhagic shock or approaching it regardless of what they report about pain location. Treat accordingly.

Compartment Syndrome

The muscles of the extremities are enclosed in tight fascial sheaths (compartments) that do not expand. When pressure builds inside a compartment — from hemorrhage, edema, burns, or crush injury — a threshold is eventually reached at which the capillary perfusion pressure falls below the compartment pressure. At that point, capillary flow stops. The tissue becomes ischemic.

The mechanism, step by step: 1. Injury causes bleeding or edema within the compartment 2. Pressure rises within the non-expandable fascial sheath 3. When compartment pressure exceeds capillary perfusion pressure (~30 mmHg threshold), capillary blood flow ceases 4. Tissue ischemia begins — muscle and nerve are both oxygen-dependent 5. Without intervention (fasciotomy — surgical scope), irreversible muscle and nerve death occurs within 6–8 hours

The 6 Ps of Compartment Syndrome:

Finding Mechanism
Pain out of proportion to injury Ischemic nerve and muscle pain; worst with passive stretch of muscles in the compartment
Pressure (tense compartment on palpation) Elevated tissue pressure in the fascial sheath
Paresthesia (tingling, numbness) Nerve ischemia — sensory nerves fail before motor nerves
Pallor Reduced distal perfusion from vascular compression
Paralysis (motor loss) Motor nerve ischemia — a late and ominous sign
Pulselessness Late sign — arterial flow is the last to stop. If you're here, the ischemia window is closing fast.

Pulselessness is a late sign because arteries are high-pressure and resist compression longer than capillaries and nerves. The EMT-B should act on the early signs (pain out of proportion + paresthesia + tense compartment) — do not wait for absent pulses.

Prehospital treatment: fasciotomy (the only definitive intervention) is surgical scope. The EMT-B's role is recognition, early transport, loose dressing over wounds, and ensuring splints are not applied too tight.

Open Fractures

When bone ends break through the skin, the fracture is open (compound). Key considerations: - Contamination risk: bone, marrow, and periosteum are now exposed to environmental pathogens; infection (osteomyelitis) is a serious complication and the reason open fractures require surgical irrigation and debridement - Bone end retraction: bone ends visible at the surface may retract back below the skin — this does not mean the fracture is no longer open; the contamination is already inside - Do not push bone ends back in — you introduce surface contamination into the wound; cover with a moist sterile dressing only - Treat as a potentially hemorrhagic wound; irrigate with saline if available and cover

Assessment Findings

DCAP-BTLS at the Injury Site

At every extremity injury, systematically assess (see dcap-btls):

  • Deformities — angulation, shortening, rotation compared to the opposite limb
  • Contusions — suggest crush mechanism or significant force
  • Abrasions — indicate sliding contact force; assess depth
  • Punctures / Penetrations — open fracture or penetrating injury to vascular structures
  • Burns — any thermal injury affecting the extremity
  • Tenderness — point tenderness over bone is highly specific for fracture
  • Lacerations — depth and proximity to bone or joint
  • Swelling — developing hematoma or edema around the fracture site

PMS: Neurovascular Assessment

Pulse, Motor, Sensation distal to the injury is the critical neurovascular check. Assess and document before and after any splint application.

Component How to Assess What Absence Means
Pulse Radial (wrist) for upper extremity; dorsalis pedis or posterior tibial for lower extremity Arterial compromise — time-critical emergency
Motor Ask patient to flex/extend fingers or wiggle toes Motor nerve injury or ischemia
Sensation Light touch or sharp/dull discrimination distally Sensory nerve injury or ischemia

Absent or diminished PMS after a long bone fracture is a time-critical finding. The patient needs vascular surgery. Expedite transport and notify the receiving facility.

Mechanism as Predictor of Severity

Energy transfer predicts injury severity. The same physics that determines injury pattern in kinematics-of-trauma applies to extremity injuries:

  • High-energy mechanisms (high-speed MVC, motorcycle crash, industrial crush, fall from height) → comminuted fractures (bone shattered into multiple fragments), higher hemorrhage volume, higher likelihood of associated vascular and nerve injury, higher likelihood of compartment syndrome
  • Low-energy mechanisms (same-level fall, minor impact in elderly) → simpler fracture patterns, lower hemorrhage, lower vascular risk — but still requires full PMS assessment

Mechanism also determines how worried you should be about associated injuries. A patient with a femur fracture from a high-speed MVC has a femur fracture AND whatever else received energy during that collision. Do not let the obvious extremity injury anchor your assessment — complete the full trauma assessment.

When NOT to Splint on Scene

Multisystem trauma patient with hemodynamic instability: if the patient is showing signs of shock and has multiple injuries, do not spend time on scene splinting. The hemorrhage control priority is the large vessel / torso injury, not the extremity. Load, go, splint en route if time allows. See load-and-go-vs-stay-and-play.

  • Priority patient (shock, altered LOC, respiratory distress): load and go — splint en route
  • Isolated extremity injury with stable vitals: splint on scene before moving the patient

EMT-B Interventions

Splinting — General Principles

  1. Splint before moving when possible — movement without immobilization is when neurovascular injury and additional hemorrhage occur
  2. Immobilize joint above AND below for long bone fractures — this prevents the bone ends from rotating around the fracture site
  3. Immobilize bone above AND below for joint injuries — prevents rotational stress at the joint
  4. Pad thoroughly — bony prominences, pressure points, and irregular surfaces all need padding to prevent pressure injury during transport
  5. Do not splint over a pulse point (radial artery, dorsalis pedis) — you will be unable to reassess the pulse if it is under the splint
  6. Position of comfort — if deformity is severe, splint in the position found rather than attempting reduction, unless PMS requires position change

Reassess PMS After Every Splint

This is not optional. A splint applied too tightly will: - Occlude distal venous drainage → increasing edema → compartment syndrome - Directly compress arteries and nerves

After every splint: check pulse, motor, and sensation distal to the injury. Worsening or new PMS deficit after splint application = loosen the splint immediately. Do not wait.

Traction Splint

Indicated for isolated mid-shaft femur fracture when all of the following are true: - Isolated injury (no multisystem trauma requiring rapid transport) - Mid-shaft location (not distal femur, not near the knee) - No contraindications (see below)

Contraindications to traction splint: - Open fracture at or near the fracture site - Fracture involves or is near the knee joint - Pelvic fracture or hip injury (the proximal attachment point would apply force to the injury) - Partial or complete amputation

Traction splint works by applying continuous longitudinal traction to the leg, which: - Pulls bone ends into better alignment (reducing the cavity volume into which blood can pool) - Reduces muscle spasm around the fracture - Decreases pain

See long-bone-immobilization for the step-by-step traction splint procedure.

Hemorrhage Control

For extremity bleeding, address hemorrhage before splinting: - Direct pressure with sterile dressings - Tourniquet if direct pressure is ineffective or impractical — apply 1–2 inches proximal to the wound, never below the elbow or knee (see bleeding-control-shock) - Elevate the injured extremity above heart level when possible to reduce venous pressure at the wound

ALS Scope — Pain Management

Extremity fractures are extremely painful. Pain management at ALS level significantly improves patient outcomes and reduces catecholamine-mediated physiological stress. This is ALS scope — not EMT-B:

  • Morphine (ALS scope): Adult 4–10 mg slow IV/IO, titrating 2–4 mg every 10 minutes. Do not administer if SBP <100.
  • Fentanyl (ALS scope): Adult 25–100 mcg slow IV/IO every 5 minutes. Do not administer if SBP <100. Note: shorter acting, often preferred in multisystem trauma.
  • Request ALS intercept for isolated extremity fractures with significant pain when transport time allows.

NM Protocol Notes

From NM EMS Treatment Guidelines (2022), External Hemorrhage/Extremity Trauma protocol:

EMT-B scope: - Primary assessment first; manage airway, breathing, circulation as indicated - Control bleeding: direct pressure → pressure dressing → tourniquet (1–2 inches proximal to wound, not below elbow or knee) - For thigh wounds: consider two tourniquets side-by-side, tighten sequentially to eliminate distal pulse - If hypotensive: transport immediately, complete assessment and treatment en route - Evaluate for deformity, shortening, rotation, instability - Assess neurovascular status: pulses, capillary refill, movement, sensation - If distal vascular function is compromised: gently attempt to restore anatomic position; strongly consider pain management before attempting to move a suspected fracture - Splint suspected fractures/dislocations; reassess distal neurovascular status after any manipulation or splinting - Elevate extremity fractures above heart level when possible - Apply ice/cool packs to limit swelling; do not apply ice directly to skin

ALS scope — pain management (not EMT-B): - Morphine: Adult 4–10 mg slow IV/IO; Pediatric 0.05–0.1 mg/kg slow IV/IO - Fentanyl: Adult 25–100 mcg slow IV/IO; Pediatric 0.5–1 mcg/kg IV/IO or IM - Consider anti-emetic (Ondansetron 4 mg) for nausea - Consider TXA in patients >15 years of age with significant hemorrhage

General Trauma Guideline (NM protocol) — scene time: The goal for unstable patients or patients requiring emergent surgical intervention is scene time less than 10 minutes, with the majority of interventions performed en route.

NREMT Relevance

Common NREMT question patterns: - Traction splint indications and contraindications — know mid-shaft femur as the indication and the four contraindications cold - PMS before and after splint — this is a checklist item; forgetting it is a critical miss on skill stations - Immobilization rule: long bone → joint above AND below; joint injury → bone above AND below - Femur fracture blood loss: 1–2 L — significant hemorrhage, treat for shock - Compartment syndrome: 6 Ps; pulselessness is a late sign - Open fracture: cover with moist sterile dressing; do NOT push bone ends back in

Sources

  • raw/protocols/nm-sop-guidelines-treatment-2022.pdf — External Hemorrhage/Extremity Trauma protocol (p. 68–69); General Trauma Guidelines (p. 59–60)