Case 01: Trauma

John Doe is a 24-year-old male brought to the emergency department following a high-speed motor vehicle collision. He was the driver and was not wearing a seatbelt. On arrival he is conscious but confused, reporting severe pain in his right leg. Examination reveals a compound (open) fracture of the tibia with visible bone ends and significant haemorrhage.

Bone is a living tissue with two main structural forms. Compact (cortical) bone forms the dense outer layer of long bones, providing mechanical strength. Beneath lies cancellous (trabecular) bone, a spongy lattice that houses red bone marrow. Bone remodelling is a continuous process governed by osteoblasts (bone formation) and osteoclasts (bone resorption). Parathyroid hormone (PTH) stimulates osteoclastic resorption when serum calcium falls, while calcitonin from the thyroid gland opposes this by promoting osteoblastic deposition when calcium is elevated.

Following fracture, healing proceeds through four stages: (1) haematoma formation from bleeding at the fracture site, (2) soft fibrocartilaginous callus formation as granulation tissue replaces the haematoma, (3) hard bony callus ossification, and (4) remodelling over months to years. The periosteum and endosteum supply osteoprogenitor cells critical to this process. In children, the epiphyseal (growth) plate must be assessed carefully as damage can permanently disrupt longitudinal bone growth.

John has lost approximately 1.5 litres of blood. A healthy adult has 4–6 litres of total blood volume (roughly 55% plasma, 45% cells). Loss of up to 10% causes no significant change in mean arterial blood pressure (MABP) due to compensatory mechanisms. Greater losses activate baroreceptors, triggering sympathetic responses: tachycardia, vasoconstriction, and increased myocardial contractility. John is showing signs of hypovolaemic shock — pallor, tachycardia, and hypotension.

Shock is classified by mechanism. Hypovolaemic shock results from fluid loss (blood, plasma, or water). Cardiogenic shock arises from pump failure (e.g., myocardial infarction). Distributive shock — including septic, anaphylactic, and neurogenic subtypes — involves widespread vasodilation reducing peripheral resistance and venous return. Obstructive shock occurs when filling or outflow is mechanically impeded (cardiac tamponade, tension pneumothorax, massive pulmonary embolus). Distributive shock presents with warm, red peripheries (vasodilation), distinguishing it from hypovolaemic shock where peripheries are cool and pale.

Pain management requires IV morphine — an opioid agonist at mu (μ), kappa (κ), and delta (δ) receptors. IV administration is mandatory in shock because impaired peripheral perfusion renders intramuscular and subcutaneous routes unreliable: drug pools at the injection site and, if circulation is restored before titration, may flood the bloodstream causing overdose. Morphine works by activating inhibitory G-proteins, reducing cAMP, opening potassium channels (post-synaptic hyperpolarisation), and blocking presynaptic calcium channels to inhibit neurotransmitter release. Adverse effects include respiratory depression (monitored by respiratory rate), bradycardia, hypotension, sedation, and nausea. Naloxone — a competitive opioid antagonist — reverses respiratory depression.

Treatment of the compound fracture follows the principles of clean (debridement), reduce, and stabilise. The open wound dramatically increases infection risk by exposing sterile tissues to the environment; it also increases blood loss, soft tissue damage, and healing time compared with a closed fracture. Compartment syndrome is a feared complication: swelling within the rigid fascial anterior compartment raises pressure above arteriole perfusion pressure, causing ischaemia, pain, numbness, weakness, and ultimately necrosis if untreated (fasciotomy required).

Prevention of road trauma injury includes primary prevention (reducing crash incidence — e.g., speed limits, drink-driving laws) and secondary prevention (reducing injury severity in the event of a crash — e.g., seatbelts, airbags, helmets). The broader impacts of trauma extend beyond the physical: mental health sequelae, financial hardship from lost income, and legal consequences (drink-driving charges) must all be addressed holistically.