Injury Severity Scores & Decision making in Mangled Limbs

Western Health Orthopaedic Registrar presentation – The Mangled Extremity: Salvaged vs Amputation by Dr Soheil Ghane Asle

Historical

There have long been guidelines to aid in surgical decision making:

Of historical interest, Frank Hastings Hamilton in the American Civil War recommended amputation for a gunshot fracture if any of the following conditions existed:

  1. patient had to be carried over rough roads
  2. bones were greatly comminuted
  3. patient suffered great pain
  4. soft parts had suffered great contusion
  5. There was extensive laceration
  6. principal arteries or nerves were involved
  7. fracture involved the knee or ankle joint

Kirk later recommended that amputation be performed if there was any disease, deformity or injury that made limb retention incompatible with life or function.

Basic principles

The most important factor is the amount of energy imparted to the tissues, & the damage this causes to nerves, vessels & the soft tissue envelope. The degree of skeletal damage is not as important.

A mangled upper extremity has a much greater impact on the patient than a mangled lower extremity, & greater efforts should be made to salvage it.

Different scoring systems

There are scoring systems developed to aid the surgeon in decision making when confronted with highly damaged lower limbs.

A prospective evaluation in Jan 2001 (Bosse et al) failed to confirm their clinical utility; the study of 556 lower extremity injuries, evaluated with the MESS, PSI, LSI, NISSSA & Hannover Fracture Scale-97, found that all studies lacked sensitivity; that is they fail to indicate to the surgeon those limbs that will later go on to amputation. The MESS in particular is of some benefit in selecting limbs that should be saved, having a high specificity.

MESS

Mangled extremity severity score, developed by Johansen in 1990. Looks at the severity of injury, ischaemia time, degree of hypotension & age of the patient. A score of more than 7 is the cutoff for amputation. The score was developed retrospectively & then validated prospectively, but later investigators have not reproduced Johansen’s results. The score is the simplest to apply & uses data available at the time of decision making.

The MESS has been applied to the upper limb in one study. Slauterbeck retrospectively reviewed the data on 43 patients with mangled upper extremities & found that all 9 with a MESS of 7 or more had undergone amputation, while all 34 with a MESS of less than 7 had undergone successful salvage.

High specificity, good at predicting limbs which should be saved.

Predictive Salvage Index (PSI)

Introduced by Howe in 1987.

Looks at level of arterial injury, degree of bony injury, degree of muscle injury & interval from injury to the operating room. Cut off point for amputation here is 8.

Nerve injury, ischaemia, soft tissue injury, skeletal injury, shock & age of patient score (NISSSA)

Developed by McNamara in 1994

Limb Salvage Index

Developed by Russell in 1991.

Involves examining 6 types of tissue. Very complex, & again not all information is available at the time of decision making.

Mangled extremity syndrome index (MESI)

Gregory 1985.

Gives points for degree of injury to skin, nervous, vascular & bone, with age, pre-existing medical condition & length of time to vascular repair. This is obviously very complex to apply. Many MESI scores are only approximate because not all the necessary data is available at the time of decision making.

The cut off for amputation is a score of 20.

Treatment

Attempts at limb salvage may lead to prolonged hospitalization, prolonged disability & high patient costs.

  1. Lange’s study
    • Looked at 23 patients, 5 underwent primary amputation, 9 delayed amputation & 9 limb salvage
    • Operations: amputation – 3; delayed amputation 6; salvage 7
    • No patient in the primary amputation group had significant functional problems, compared with 50% in the limb salvage & delayed amputation group
  2. Fairhurst looked at grade III open tibial fractures & found that 12 patients who had early amputation were all back at work within 6 months, while those patients who had late amputation following attempted salvage got back to work at 36 months & those who had limb salvage got back to work at 18 months
  3. Georgiadis’ study
    • Got patients to fill out a quality of life evaluation tool, the General Well Being Schedule. Significantly more patients in the limb salvage group considered themselves severely disabled

Practical points

  1. Obtain photos for the medical record
  2. If amputation is decided upon, get another senior clinician to see & document in the notes that they concur with amputation
  3. Use the injury scoring systems as guidelines only
  4. If at all possible, salvage above knee injuries, as the functional outcome is so much poorer
  5. Try to salvage the upper limb
  6. In adults, complete irrevocable loss of the sciatic or posterior tibial nerve is an indication for amputation
  7. If in doubt, attempt limb salvage but be prepared for early amputation