5.4 Fractures, Dislocations, Joint Pain, & Musculoskeletal Emergencies

Fractures, Dislocations, Joint Pain, & Musculoskeletal Emergencies

Musculoskeletal trauma and acute arthropathies require prompt systematic evaluation to prevent permanent neurological deficit, avascular necrosis, limb loss, or systemic sepsis.

---

Compartment Syndrome & Open Fractures

Compartment Syndrome

• Pathophysiology: Elevated tissue pressure within a closed fascial compartment exceeds capillary perfusion pressure, leading to muscle and nerve ischemia. Most common sites: Anterior compartment of the lower leg (post-tibia fracture) and volar compartment of the forearm (Supracondylar humerus fracture in children).
• Clinical Presentation (The 6 Ps):
  1. Pain out of proportion to injury (Earliest and most sensitive physical sign)
  2. Pain on passive stretch of compartment muscles (Most specific early exam finding)
  3. Paresthesias (Nerve ischemia in distribution of compartmental nerves, e.g., deep peroneal nerve in anterior leg)
  4. Pallor (Late sign)
  5. Paralysis (Late sign indicating irreversible muscle necrosis)
  6. Pulselessness (Extremely late sign; peripheral pulses often REMAIN PRESENT early!)
• Diagnosis: Primary clinical diagnosis. In unconscious/obtunded patients, measure intracompartmental pressure. Absolute pressure $> 30\text{ mmHg}$ or Delta pressure (Diastolic BP $-$ Compartment pressure) $< 30\text{ mmHg}$ confirms compartment syndrome.
• Management: EMERGENT OPERATIVE FASCIOTOMY (e.g., two-incision 4-compartment leg fasciotomy). Release all tight dressings/casts immediately. Do NOT elevate the limb (elevating reduces arterial perfusion gradient).

---

Open Fractures (Gustilo-Anderson Classification)

• Gustilo Type I: Clean wound $< 1\text{ cm}$. Low energy. Antibiotics: Cefazolin.
• Gustilo Type II: Wound $> 1\text{ cm}$ without extensive soft tissue damage. Antibiotics: Cefazolin.
• Gustilo Type III: High energy, extensive soft tissue trauma, severe contamination, or open segmental fracture.
  • IIIA: Adequate soft tissue bone coverage. Antibiotics: Cefazolin + Gentamicin (add Penicillin G for soil/barnyard contamination).
  • IIIB: Extensive soft tissue loss requiring local or free flap coverage.
  • IIIC: Open fracture associated with major arterial injury requiring repair.
• Emergency Management: Tetanus prophylaxis, immediate IV antibiotics within 3 hours, sterile saline dressing, splinting, and emergent operative irrigation and debridement within 24 hours.

---

High-Yield Fractures & Clinical Decision Rules

Scaphoid Fracture

• Mechanism: Fall on an outstretched hand (FOOSH).
• Physical Exam: Tenderness in the anatomical snuffbox and pain with axial loading of the thumb.
• Complication: Avascular necrosis (AVN) of the proximal pole due to retrograde blood supply from the dorsal carpal branch of the radial artery.
• Management: If snuffbox tenderness is present, apply a thumb spica splint even if initial X-rays are completely normal. Repeat X-rays in 10–14 days or obtain an immediate MRI.

---

Ottawa Decision Rules for Imaging

Validated clinical decision rules with near $100%$ sensitivity designed to eliminate unnecessary radiographs.

1. Bone tenderness along posterior 6 cm of distal lateral malleolus
2. Bone tenderness along posterior 6 cm of distal medial malleolus
3. Inability to bear weight both immediately after injury and in ED for 4 steps | | Ottawa Foot Rules | Foot series required if pain in midfoot zone AND any of:
4. Bone tenderness at the base of the 5th metatarsal
5. Bone tenderness at the navicular bone
6. Inability to bear weight both immediately after injury and in ED for 4 steps | | Ottawa Knee Rules | Knee series required for acute knee injury patients with ANY of:
7. Age $\ge 55$ years
8. Isolated tenderness of patella (no other bone tenderness)
9. Tenderness at the head of the fibula
10. Inability to flex knee to 90 degrees
11. Inability to bear weight both immediately and in ED for 4 steps |

---

Joint Dislocations & Associated Nerve Complications

Acute Monoarthritis: Septic Joint vs. Crystal Arthropathy

An acute, hot, swollen monoarticular joint is a medical emergency until septic arthritis is excluded.

Synovial Fluid Analysis Guidelines

• Septic Arthritis Management: Immediate arthrocentesis before antibiotics. Empiric IV Vancomycin (plus Ceftriaxone if Gram-negative or young sexually active adult) AND emergent surgical joint drainage (arthroscopic or open wash-out).
• Pediatric Septic Hip (Kocher Criteria): Non-weight bearing, ESR $> 40\text{ mm/h}$, Fever $> 38.5^\circ\text{C}$, WBC $> 12,000/\mu\text{L}$. Score $\ge 3$ indicates $> 93%$ probability of septic hip; requires urgent ultrasound-guided aspiration and surgical drainage.