Mangled Extremity Severity Score (MESS) Calculator

How does this Mangled Extremity Severity Score (MESS) calculator work?

This health tool evaluates the degree of severity in a trauma suffered in the limbs and predicts the level of viability/risk of amputation based on several patient conditions as described below:

■ Age – with three age categories represented, below 30, between 30 - 50 and above 50.

■ Limb ischemia for more than 6 hours – at this question, the patient is invited to answer with yes or no. In case the answer is yes, regardless of the answer to limb ischemia question, the points are doubled.

■ Limb ischemia – to different stages, either just reduced pulse with normal perfusion, lack of pulse with slow capillary refill or paralysis and numbness.

■ Shock present – circulatory system symptoms at presentation indicating shock, either transiently hypotension or persistent hypotension.

■ Injury mechanism – ranging from low to very high impact energy. Simple fractures, stabbings or gunshots are considered low, dislocations or multiple fractures have medium energy while high spend MVA, rifle shots and in general most high speed trauma are at the high end, usually resulting in gross contamination from the exposure to the environment.

The Mangled Extremity Severity Score (MESS) offers an early prognosis, similar to other tools such as the Revised Trauma Score but in particular, MESS can discriminate between empiric amputation or whether the limb can still be saved.

It is most often used for lower extremity trauma in the emergency department during the initial evaluation in the trauma assessment centre. During that, the clinician might also use the Gustilo Classification of injury, stating whether the wound is grade I, II or III while observing the bone puncture and tissue and vascularisation damage.

The cut off is set at 7, with score below presenting a better prognosis while score above 7 presenting a higher risk of amputation and negative outcome.

What still needs to be considered is that no score can be as exact as to predict 100% amputation and that clinical judgment is crucial in every case, but this system does provide useful information to the clinician even in cases where skeletal or soft tissue repairing and reconstruction are necessary.

MESS guidelines

The original version was set to simply discriminate the need for amputation while focusing on the degree of injury at skeletal and soft tissues level, the degree of ischemia and whether the patient presents any shock symptoms due to the trauma suffered. It accounted for a study with 250 lower extremity trauma patients at the Harborview Medical Center in Seattle. The initial results indicated a cut of level at the score of 6. A derived larger center study then settled to the score of 7 as the 100% cut off for amputation procedures.

As a scoring system, the original MESS model was found to have a poor specificity but high sensitivity in scoring trauma patients with extremities injuries thus allowing triage, classification and outcome prediction. Plus it allows a better resource efficiency cost, especially in patients who were previously delayed amputation although the limbs could not be salvaged. Some of the anatomic trauma assessments to be used alongside to evaluate the severity degree of the injury include:

■ Abbreviated Injury Score (AIS);

■ Injury Severity Score (ISS);

■ Anatomic Profile (AP);

■ Penetrating Abdominal Trauma Index (PATI);

■ Trauma Score - Injury Severity Score (TRISS).

References

1) Johansen K, Daines M, Howey T, Helfet D, Hansen ST Jr. (1990) Objective criteria accurately predict amputation following lower extremity trauma. J Trauma; 30(5):568-72; discussion 572-3.

2) Togawa S, Yamami N, Nakayama H, Mano Y, Ikegami K, Ozeki S. (2005) The validity of the mangled extremity severity score in the assessment of upper limb injuries. J Bone Joint Surg Br; 87(11):1516-9.

3) Kumar MK, Badole C, Patond K. (2007) Salvage versus amputation: Utility of mangled extremity severity score in severely injured lower limbs. Indian J Orthop; 41(3):183-7.

4) Helfet DL, Howey T, Sanders R, Johansen K. (1990) Limb salvage versus amputation. Preliminary results of the Mangled Extremity Severity Score. Clin Orthop Relat Res; (256):80-6.