David Sanders, M.D., MSc, FRCSC
Assistant Professor, Orthopaedic Trauma
Victoria Campus, London Health Sciences Centre

Management of the mangled extremity is one of the most challenging tasks in orthopaedic trauma care. Deciding whether amputation or reconstruction is best for an individual patient is a complex decision. Patient related factors, injury factors, and institutional capabilities must all be considered in the assessment of treatment strategy in order to achieve the best possible outcome.  

Evaluation and Scoring Systems
Although a variety of scoring systems are helpful in determining whether to amputate or reconstruct, many factors need to be considered, and nerve integrity to the limb is one of the most important factors. The absence of tibial nerve function is felt by some to be of singular importance in predicting outcome, however, a useful limb can be reconstructed even in the absence of plantar sensation. Limb ischemia is critical. The ability to rapidly restore perfusion is essential to a successful reconstruction. Integrity of the soft tissue envelope is a third important variable. Damage to the skin or muscle can complicate the reconstructive or ablative procedure. As well, severe damage to multiple muscle compartments is an important variable associated with poor outcome. Although bone loss complicates reconstruction, it is a less important determinant of the ability to reconstruct a limb, primarily due to improvements in reconstructive techniques. Finally, the overall condition of the patient will determine whether multiple surgeries and reconstruction can be tolerated and should be considered.

Scoring systems have been developed to assist with the prediction of which limbs might be salvaged. The Mangled Extremity Severity Score was developed in 1990. This scoring system is divided into four components: skeletal and soft tissue injury, graded from 1 to 4; limb ischemia, graded from 1 to 3; shock, graded 0 to 2; and patient age graded from 0 to 2. In general, a MESS score of less than 7 is felt to indicate an excellent likelihood of successful limb salvage.

Other scoring systems in use include the Limb Salvage Index (LSI), the Predictive Salvage Index (PSI), the Nerve injury, Ischemia, Soft tissue injury, Skeletal injury, Shock, and Age Index (NISSSA), and the Hanover Fracture Scale-97 (HSF-97). All of the scoring systems apply a numerical value to the severity of injury, which can be used to predict the need for amputation. In general, low scores in any of the scales can be used to predict successful limb-salvage potential, but high scores do not have adequate sensitivity to predict amputation. Therefore, although scoring systems may be helpful, the treating surgeon must rely on clinical judgement in deciding how best to treat a mangled limb.

Outcome of Amputation and Limb Salvage
Many important factors affect the outcome of reconstructive efforts. One of the primary concerns of patients is time and cost to achieve maximum medical improvement. There is no doubt that reconstruction requires costly, intensive and prolonged medical treatment. Patients often miss out on their work and recreational activities for over a year. In contrast, early prosthetic treatment is thought to offer the potential of a speedier return to full function at a much lower initial cost.

Recently, a multicentre prospective outcome study of 601 patients has provided valuable information regarding outcomes after high-energy lower extremity trauma treated with amputation or reconstruction. Results from the Lower Extremity Assessment Project, or LEAP study, have indicated that the advantages to early amputation may not be as great as previously thought. For example, self-reported health status was not significantly different at two years following injury between the amputation and reconstruction groups. These results were particularly surprising because most patients treated with amputation have achieved maximum improvement two years post-injury, whereas reconstructed limbs often require additional procedures to achieve union or soft tissue coverage. Other interesting results from the LEAP study have shown that the most important overall predictors of outcome, regardless of treatment strategy, include low level of education and poor socio-economic status, underlining the importance of patient factors in major lower extremity trauma.

Treatment of the mangled extremity continues to evolve. Faced with the difficult decision of limb salvage versus reconstruction, the surgeon should consider patient, injury, and institutional factors. Results from the LEAP study suggest that results of reconstruction are promising. Efforts to improve limb salvage and reconstruction techniques should be continued. Perhaps, improvements in outcome may also entail attention to non-clinical interventions, such as social or vocational rehabilitation.

References:

1. Bosse M.J., MacKenzie E.J., Kellam J.F., et al. A prospective evaluation of the clinical utility of the lower-extremity injury-severity scores. J Bone Joint Surg Am. 2001 Jan;83-A(1):3-14.
   
   
2. Dirschl D.R., Dahners L.E. The mangled extremity: when should it be amputated? J Am Acad Orthop Surg 1996 Jul; 182 – 190.
   
   
3. Swiontkowski M.F., MacKenzie E.J., Bosse M.J., et al. Factors influencing the decision to amputate or reconstruct after high energy lower extremity trauma. J Trauma 2002; 52: 641-649.
   
   
4. Bosse M.J., MacKenzie E.J., Kellam J.F., et al. An analysis of outcomes of reconstruction or amputation of leg threatening injuries. N Engl J Med 2002; 347: 1924-1931.