MESS = skeletal and soft-tissue injury points + limb-ischaemia points + shock points + age points. Double the limb-ischaemia points when warm ischaemia lasts >6 hours. The implemented total range is 2–14.

Domain	Category	Definition	Points
Skeletal and soft-tissue injury	Low energy	Stab wound, simple fracture or low-velocity pistol gunshot	1
	Medium energy	Open or multiple fractures, dislocation or moderate crush	2
	High energy	High-speed motor vehicle crash, rifle gunshot or severe crush	3
	Very high energy	Gross contamination or farm or industrial mechanism	4
Limb ischaemia	Mild	Pulse reduced or absent with clinically normal perfusion	1
	Moderate	Pulseless limb with paraesthesia and diminished capillary refill	2
	Advanced	Cool, paralysed and insensate limb	3
Shock	Normotensive	Systolic BP ≥90 mmHg throughout resuscitation	0
	Transient hypotension	Systolic BP <90 mmHg and responds to resuscitation	1
	Persistent hypotension	Systolic BP <90 mmHg despite resuscitation	2
Age	<30 years		0
	30–50 years		1
	>50 years		2

Scores 0–6 are below the classic threshold. Scores ≥7 are classified as high MESS.

Mangled Extremity Severity Score (MESS)