Management of the Mangled Extremity
The optimal management of patients with mangled extremities after trauma remains controversial. Although these injuries are not common,1 they represent significant management challenges that require careful consideration of complex clinical factors affecting outcome. Limb salvage efforts require extensive resources and a prolonged hospitalization. Even when successful, multiple reconstruction procedures may be necessary to achieve a good long-term result. Failed attempts at limb salvage are associated with increased cost and adverse patient outcomes. Therefore, the decision process for the care of a mangled extremity requires a systematic approach that adequately considers all factors.
Many predictors of adverse outcome after mangled extremities have been identified,2–6 and several groups have proposed the use of predictive scoring systems to determine the need for amputation after these injuries7–14 (Table 2). In 1987, Howe et al.7 performed a retrospective review of 21 injured limbs to determine which variables influenced salvage or loss after trauma. This group found that a Predictive Salvage Index (PSI), consisting of weighted scoring of the level of vascular injury, degree of osseous injury, degree of muscle injury, and warm ischemia time, was 78% sensitive and 100% specific in predicting subsequent amputation. In 1990, Johansen et al.8 proposed the utilization of the Mangled Extremity Severity Score (MESS) which was developed through an examination of 25 patients with severe limb injuries. The MESS consists of four primary risk considerations, including skeletal/soft tissue injury, limb ischemia, shock, and age. These investigators then prospectively validated the score in 26 severely injured limbs, concluding that a MESS of 7 was 100% predictive of amputation.
A subsequent study conducted by McNamara et al.4 outlined the development and utilization of a nerve injury, ischemia, soft tissue injury, skeletal injury, shock, and age of patient (NISSSA) score, which added consideration of the nerve component of injury. The NISSSA score gave the greatest weight to the loss of plantar sensation and also divided tissue injury into soft tissue and skeletal components. In 26 injured limbs, the NISSA score was found to be both more sensitive (81.8% vs. 63.6%) and more specific (92.3% vs. 69.2%) than the MESS. Other scoring systems, including the Limb Salvage Index (LSI) proposed by Russell et al. in 19919 and the Hannover Fracture Scale11 have also been used to predict the need for amputation after trauma.
All these scoring systems, however, have failed to prove their validity in larger prospective examinations. In 2001, Bosse et al.14 conducted a prospective evaluation of available scoring systems in an examination of 556 highenergy lower-extremity injuries. They examined the sensitivity, specificity, and area under the receiver operating characteristic curve for MESS, LSI, PSI, NISSSA score, and the Hannover Fracture Scale for both ischemic and nonischemic limbs. Their analysis was conducted in two ways: including and excluding limbs that required immediate amputation. These investigators were unable to demonstrate the validity of these scoring systems. Although all had high specificity for prediction of limb salvage when the scores were low, the sensitivity of the indices failed to support the validity of any scoring system as an adequate predictor of amputation.14 Ly et al. and the LEAP study group10 would follow this investigation, in 2008, with analysis of a cohort of patients who participated in a multicenter prospective study of clinical and functional outcomes after high-energy lower extremity trauma. They examined 407 subjects for whom reconstruction was considered successful at six months and found that none of the retrospectively validated scoring systems (MESS, LSI, PSI, NISSSA score, or the Hannover Fracture Scale) were predictive of the Sickness Impact Profile outcomes at six months or 24 months. In addition, none of these scoring systems predicted patient recovery between six months and 24 months. They concluded that no currently available Injury Severity Score was predictive of functional recovery of patients who undergo successful limb reconstruction.
In the absence of an adequate scoring system, the management of the patient with a mangled extremity requires a multidisciplinary approach and careful consideration of complex systemic and limb-related factors. Optimal outcome requires the trauma provider to evaluate these factors systematically to determine the appropriate choice between limb salvage procedures and amputation.