Synopsis
Translate sensory, motor and Doppler findings into Rutherford viability categories that determine imaging tolerance, revascularisation urgency and when reperfusion is futile.
- Rutherford I has no sensory or motor loss with audible arterial and venous signals; IIa has none or toe-only sensory loss, no weakness, absent arterial but present venous signal.
- Rutherford IIb has sensory loss beyond the toes or rest pain plus mild to moderate weakness: contact vascular surgery immediately, anticoagulate unless contraindicated, and perform emergency revascularisation without imaging delay.
- Rutherford III has profound anaesthesia, profound paralysis or rigor, absent arterial and venous signals and usually fixed skin change: seek senior confirmation, then primary amputation or palliation rather than reperfusion.
Key red flags
New mild or moderate muscle weakness moves the limb into Rutherford IIb even when venous Doppler flow or some capillary refill remains.
Sensory loss extending beyond the toes or rapidly spreading numbness indicates immediate threat and shortens the acceptable imaging window.
Profound anaesthesia, complete paralysis or rigor, absent capillary refill and absent arterial and venous Doppler signals strongly suggest Rutherford III.
Deterioration from IIa to IIb during observation or transfer requires direct communication and emergency rather than prompt revascularisation.
Active major bleeding or current or previous immune HIT changes anticoagulation but not the need for immediate vascular assessment.
No sensory loss and normal motor function occur with audible arterial and venous Doppler signals; the limb is not immediately threatened but still needs urgent assessment.
Sensation is normal or minimally reduced at the toes, motor power is normal, arterial signal is absent and venous signal remains audible; prompt treatment can salvage the limb.
Sensory loss extends beyond the toes with rest pain and mild to moderate weakness; absent arterial but preserved venous signal accompanies an immediately threatened salvageable limb.
Profound anaesthesia and paralysis or rigor occur with absent arterial and venous signals, absent refill and established tissue injury, making meaningful salvage unlikely.
Map and time the boundary of light-touch loss because extension from toes into the forefoot or more proximally can convert IIa to IIb.
Test active toe and ankle movement repeatedly; any new ischaemic weakness is a decisive escalation feature even before complete paralysis develops.
Early pallor or mottling may blanch, whereas fixed non-blanching mottling, cool rigid muscle and loss of refill support irreversible tissue damage.
Reasoning priorities
Define the distribution and progression of ischaemic nerve dysfunction.
No loss supports I; toe-only loss fits IIa; loss beyond toes supports IIb; profound anaesthesia supports III. Pain and analgesia can confound cooperation, so record method and limitations.
Worked reasoning
A patient initially has toe-only numbness and no weakness, then develops reduced ankle dorsiflexion while awaiting CTA.
- Initial inputs are absent arterial but preserved venous Doppler signal, sensory loss confined to toes and normal active toe and ankle movement, supporting Rutherford IIa.
- Repeat examination detects sensory extension beyond the toes and new dorsiflexion weakness, so the reasoning changes the category from marginal IIa to immediate IIb threat.
- Tell the vascular clinician immediately, continue UFH when safe and redirect the pathway toward emergency revascularisation rather than waiting for delayed imaging.
- Verify the change by documenting time, exact muscle movements, sensory boundary and Doppler sites while monitoring physiology through transfer.
- After reperfusion, confirm haemodynamic and neurological response and monitor potassium, kidney function and compartments.