Chapter 44 Mangled Extremity: Are Scoring Systems Useful?
The decision to proceed with amputation or salvage of a mangled extremity is one of the most challenging decisions in orthopedic trauma. Orthopedic trauma surgeons are highly skilled at exercising heroic attempts at limb salvage. However, unsuccessful attempts at salvage are extremely costly and carry with them high morbidity and prolonged rehabilitation. Amputation, on the other hand, is commonly feared by patients. In an attempt to aid in the decision-making process regarding the need for amputation or salvage, a number of predictive indices have been proposed. All of these indices attempt to identify limbs for which salvage or amputation would be preferred.
Advances in care of the traumatized patient including microvascular surgery, nerve reconstruction, tissue transfer, and fracture management continue to expand the orthopedic trauma surgeon’s ability to preserve limbs. However, prolonged, costly, and morbid attempts at preservation may, indeed, be worse than the results of early amputation. As suggested by prominent experts in limb reconstruction,1 this may leave the patient “demoralized, divor-ced and destitute.”
Many considerations must be factored in when making the difficult decision regarding amputation versus limb salvage. These include vascular status, infection risk, tissue devitalization, fracture instability, social impact, physical healing potential, and probably psychological healing potential.2
OPTIONS: SCORING SYSTEMS
Surgeons intuitively recognize that some limbs are frankly beyond salvage, whereas in other cases, a reasonable possibility of limb salvage and restoration of function exists. For centuries before the development of scoring systems, surgical indications for amputation were considered. Kirk,3 in 1943, noted indications for amputation included any injury or disease rendering limb salvage incompatible with function. Absolute and relative indications for amputation after open tibial fractures with vascular injury were described by Lange and colleagues4 in 1985. Absolute indications included anatomically complete disruption of the posterior tibial nerve and a crush injury with a warm ischemic time greater than 6 hours. Relative indications included serious associated polytrauma, severe ipsilateral foot trauma, and an anticipated protracted reconstructive course. The authors specify that their indications for primary amputation included either of the absolute indications or two to three relative indications. Although never validated, this type of classification scheme illustrates several crucial elements of decision making used by experienced surgeons.
Mangled Extremity Syndrome Index
In 1985, Gregory and coworkers’5 severity grading system for multisystem extremity injury entitled “The Mangled Extremity Syndrome Index” (MESI) was published. This scale uses a point score system including the degree of injury severity score to reflect polytrauma, skin injury, nerve injury, vascular injury, bone injury, lag time to surgery and age in years, as well as preexisting disease and shock. In retrospective work, 100% of patients with an MESI of greater than 20 required amputation. However, the patient mix was heterogeneous. Concerns surrounding the MESI include the complexity and the subjectivity of the scoring system. In Roessler and coauthors’ retrospective study6 using this scoring system, the MESI predicted amputation incorrectly in five patients and incorrectly predicted salvage in four patients.
In a second study, Bonanni and colleagues7 note that the sensitivity of the MESI to predict amputation was low at only 6%; specificity was 90%. Both Bonanni and colleagues7 and Roessler and coauthors6 note that many variables included as part of the MESI were unavailable at the time of the initial assessment of the patient, making it impossible to apply this scoring system accurately.
Predictive Salvage Index
The predictive salvage index (PSI) system was introduced by Howe and researchers.8 Patients with combined orthopedic and vascular injuries were studied. Only patients with lower extremity injuries were included. The PSI system is a simplified variation of the MESI. Points are given for the level of arterial injury, the degree of bone injury, the degree of muscle injury, and the interval from injury to the operating room. An initial retrospective analysis of the PSI was performed in 21 patients. All patients who achieved salvage had a PSI < 8. In contrast, seven of nine patients who required amputation scored 8 or greater. Conclusions from this retrospective study suggest that the sensitivity of the PSI was 78% and specificity was 100%. Bonanni and colleagues7 applied the PSI retrospectively to their data as well. They found that the PSI predicted amputation with a specificity of 70%, but sensitivity of only 33%. Roessler and coauthors6 also found that the PSI predicted amputation for two patients who ultimately had their limb salvaged and predicted salvage for five patients who ultimately required amputation.
Mangled Extremity Severity Score
The mangled extremity severity score (MESS) may be the most commonly applied and heavily researched lower extremity scoring index. The MESS system was introduced by Johansen and investigators9 in 1990. Only five criteria are included in the MESS: skeletal and soft-tissue injury, limb ischemia, shock, and age. The initial MESS analysis was based on a retrospective review of 26 mangled lower extremities. It was subsequently validated in a prospective trial at a different trauma center involving 26 patients.10 In both the original retrospective analysis and the prospective trial, a MESS score of less than 7 predicted salvage with 100% accuracy. Advantages of the MESS system include simplicity and a relatively more thorough validation compared with the PSI or MESI. However, it remains subjective and includes, in particular, consideration of contamination as a relevant issue surrounding the degree of energy.
MESS data retrospectively applied by Robertson11
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