Rethinking Proper Patient Selection For Limb Salvage Interventions

By Ronald A. Sage, DPM

   Six weeks later, surgeons fitted the patient with a prosthesis and he began rehabilitation. Although he took early retirement, the patient has returned to independent community ambulation. Had the surgeons performed the transtibial amputation after the failed toe amputation, three operations would have been eliminated from this patient’s five-stage below-knee amputation. His case illustrates the fact that in spite of our best efforts, all limbs with diabetic complications are not salvageable.

   Both patients had low normal levels of serum albumin at approximately 3.0 gm/dl. Their total lymphocyte counts were both above 1,700. Their ankle brachial indices were about 0.3 before their vascular procedures and 0.45 afterward. They both had heart disease but who had more severe heart disease? The 58-year-old patient had worse control but the 62-year-old patient had early renal disease. If one measured the degree of control, nutritional status, renal function and cardiac function, would a significant difference between the two in any of these parameters be predictive of their eventual outcome? Right now, we do not know but the fact that many limb salvage attempts fail suggests we should find out.

Why There Is A Need For Enhanced Limb Salvage Criteria

   A recent study performed at the University of Texas Health Science Center in San Antonio reviewed 277 diabetic patients who underwent a first amputation between 1993 and 1997. This study included patients who had partial foot amputations and those who had major lower extremity amputations. Researchers found that patients in their series were at greater risk for further amputation on the same side as the first procedure than they were for contralateral amputation. They concluded that this finding should influence clinicians to implement preventive efforts in patients undergoing a first amputation.1 While it is hard to disagree, one might also argue that the data suggests that patient selection criteria for distal procedures may need refinement in order to avoid multi-staged higher amputations.

   In an earlier, thought-provoking study, Duggan reviewed 38 patients who underwent bypass procedures for critical limb ischemia and reported an 80 percent limb salvage rate, and a 58 percent three-year survival rate. However, only 25 percent of the patients were ambulating after these interventions.2 This study raises the question that even if limb salvage is successful, do all of these patients truly benefit, given the postoperative risks and potential morbidity associated with these efforts?

   These studies and the two case histories demonstrate that while limb salvage remains an important goal for patients who suffer lower extremity complications of diabetes, aggressive limb salvage efforts may not benefit everyone. To date, we have relied on limited criteria to choose candidates for partial foot procedures as opposed to amputations at higher levels. Such criteria include Doppler studies, measurement of trancutaneous oxygen, evaluation of serum albumin and measurement of total lymphocyte counts. If we are going to avoid putting our sickest patients through multiple futile attempts at limb salvage, we need to expand and redefine this criteria.

   Anecdotally, a closer look at patients in our facilities who fail limb salvage interventions suggests that diffuse vascular disease, uncontrollable infection, inadequate offloading and numerous medical conditions appear to be associated with failure of foot wound debridement and partial amputations. These medical conditions include chronic poor control of diabetes, hypoalbuminemia, renal disease and cardiac disease. Unfortunately, many patients who suffer lower extremity complications of diabetes also present with these comorbidities.

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