SLR - September 2012 - Scott Hoffman
Reference: Landry GJ, Silverman DA, Liem TK, Mitchell EL, Moneta GL, Arch Surg. 2011 Sep;146(9):1005-9.
Scientific Literature Review
Reviewed by: Scott Hoffman, DPM
Residency Program: St. John Hospital and Medical Center - Detroit, Michigan
Podiatric Relevance:
For the podiatric surgeon, transmetatarsal amputation is often the last attempt at partial foot salvage in patients with distal foot gangrene. Preservation of a sensate heel is desirable for maintaining ambulatory function. However, wound healing of TMA is often met with challenge and a non-healing TMA commonly leads to multiple operations and hospitalizations. Frequently, the end result is a more proximal (often transtibial) amputation. The examiners developed a study in an attempt to predict which patients are less likely to heal TMA and may be better served initially with a more proximal amputation with a higher likelihood of healing.
Methods:
A retrospective analysis of outcomes of 62 consecutive transmetatarsal amputations performed at Oregon Health & Science University from January 1, 2004 through December 31, 2010 was conducted. Revascularization before amputation was performed at the discretion of the surgeon if perfusion for wound healing was believed to be inadequate. In the absence of gross infection, wounds were primarily closed, whereas grossly infected wounds were left open at the initial operation for delayed primary or secondary closure. Non-weightbearing status for one month was encouraged. Both intraoperative and postoperative factors that are believed to potentially affect wound healing were assessed. Univariate and multivariate analyses were conducted to assess factors associated with TMA healing. Limb salvage and survival were calculated with Kaplan-Meier analysis. The level of significance was set at P < .05.
Results:
Thirty-three of 62 TMAs (53 percent) healed, 22 of 62 (35 percent) resulted in below-knee amputation, and in seven of the TMAs (11 percent), the patient died without TMA healing. There was no difference in wound healing between primary and delayed primary or secondary closure (P=.39). At the time of amputation and following any attempted revascularization procedure, 35 patients had measurable ankle brachial indices with a mean of 0.96, whereas 27 had non-compressible ABIs. Measurement of skin perfusion pressures did not predict subsequent TMA healing. There was a trend toward decreased healing in patients with renal failure, chronic obstructive pulmonary disease, and cardiac disease. Other factors, including a history of diabetes, did not influence TMA healing. Non-healers underwent a mean of four operations from the time of their initial operation to either below-knee amputation or death. None of the patients with healed TMA required further amputation or operations.
The mean survival of the entire patient cohort was 16.5 months (range, 0-94 months). Mean survival did not differ between patients with and those without TMA healing (15.1 vs. 18.0 months; P=.52). Univariate and multivariate predictors of mortality included renal failure (74 percent mortality in patients with renal failure vs. 40 percent in patients without; P=.03), non-ambulation (62 percent vs. 36 percent; P=.04), non-independent living (79 percent vs. 21 percent; P<.001), and pre-TMA revascularization (64 percent vs. 31 percent; P=.01).
Conclusions:
TMA healing rates are poor, even with experienced surgeons and careful preoperative planning. Patients should be made aware of the uncertainty of the procedure and the need for meticulous postoperative compliance to optimize the chances of success. Given the poor ambulatory performance of atherosclerotic patients with transtibial amputations, it is reasonable to pursue TMA in patients with a higher likelihood of continued ambulation despite the accepted lower healing rates. In patients with poor rehabilitation prospects, TMA may lead to additional procedures and hospitalizations, and a more proximal amputation with a higher likelihood of healing may be preferable.