Orthopaedic indications for amputation
Amputation is considered when a limb becomes either non-viable, threatens systemic health, or is no longer functional or reconstructable with acceptable outcomes.
Major trauma: Amputation may be indicated for mangled extremeties, open fractures with vascular injury, traumatic amputations and severe crush injuries. Hard indications for amputation include irreversible ischaemia (>6 hours of warm ischaemia, insensate, fixed mottling, no capillary refill) and traumatic amputation. Mangled extremeties involve multi-factorial orthoplastic decision-making with surgical judgement of skeletal, soft tissue and neurovascular loss and subsequent reconstruction and functional recovery potential. Patients with MESS score >7 are considered for amputation.
Compartment syndrome: Patients with extensive non-viable soft tissue loss, fixed contractures and complete neurological loss should be considered for amputation —as reconstruction to a functional limb is unlikely. BOAST guidelines identify that any patient with a delayed presentation/diagnosis of compartment syndrome (>12 hours) should have multi-consultant decision-making and may not be suitable for limb-preserving surgery. In patients with >24 hours of warm ischaemia, attempts to preserve the limb are likely to be associated with reperfusion injury and systemic complications.
Infection: Necrotising fasciitis and osteomyelitis are the two most common infections leading to amputation. In necrotising fasciitis, amputation should be considered when there is circumferential multi-compartment spread leading to non-viable muscle. It may also be considered for those with persisting sepsis or spreading fasciitis despite aggressive debridement. In patients with osteomyelitis, those with diabetic foot infections are the highest risk for amputations. Amputation should be considered when active bone infection persists despite multiple antibiotic course and limb-preserving surgical attempts. It may also be considered for source control in patients who are severely unwell due to systemic sepsis, with a lower threshold for amputation in patients who are frail and multi-morbid.
Tumours: Malignancies which are resectable but require large-scale debridement to achieve adequate margins or multiple staged surgeries may be considered for amputation —in addition to malignancies which have invaded local neurovascular structures. This is usually an MDT decision, taking into account MRI evidence of invasion, performance status, expected survival and radiation field constraints.
Vascular: Most amputations underlaid by a vascular cause are performed under vascular expertise. Vascular indications for amputation may include: acute limb ischaemia (>6 hours warm ischaemia), chronic ischaemia leading to gangrene and limb-preserving treatment failures (such as rest pain despite repeated failed revascularisation procedures and medial optimisation).
Types of amputation
Primary: Amputation is performed as the first line procedure.
Secondary: Amputation is performed as a second line procedure, after limb-preserving interventions have failed.
Tertiary (aka. revision): Patients with previous amputation who now require a more proximal amputation.
Traumatic: Amputation occurs as part of a major traumatic injury.
Levels of amputation