Factors Associated with Unsuccessful Revascularization Surgery in Traumatic Upper-Extremity Amputation

Abstract

Background: Microsurgical emergency revascularization surgery for traumatic upper-extremity amputations demands high resource use. Injury details and patient characteristics influence the decision of whether to revascularize or revise an amputation involving the upper extremity. Our aim was to study associations between those factors and unsuccessful revascularization to provide information for clinical decision-making regarding amputation injuries.

Methods: We studied all consecutive patients who had undergone an upper-extremity revascularization at Tampere University Hospital between 2009 and 2019. The primary outcome was the technical success or failure of the operation, which was defined as the survival or non-survival of the amputated tissue. Using logistic regression, we analyzed prognostic factors including age, sex, smoking status, diabetes mellitus, injury mechanism (cut, crush, or avulsion), extent of tissue loss before treatment (number of lost joints), and amputation type (total or subtotal).

Results: A total of 282 patients (mean age, 47 years; 14% female; mostly White Caucasian) were included. The proportion of successful revascularizations (survival of all reconstructed tissue) was 76% (214 of 282). An avulsion injury mechanism (adjusted odds ratio [aOR], 5.9; 95% confidence interval [CI], 2.5 to 14.2), crush injury mechanism (aOR, 2.8; 95% CI, 1.1 to 7.0]), and total amputation type (aOR, 2.9; 95% CI, 1.5 to 5.8) were the prognostic factors that were associated with the highest risk of unsuccessful revascularizations. We found an S-shaped, nonlinear association between patient age and unsuccessful revascularizations and a U-shaped, nonlinear association between the amount of tissue loss before treatment and unsuccessful revascularizations. There was no evidence of an association between unsuccessful revascularizations and patient sex, smoking, or diabetes mellitus.

Conclusions: Injury details were the most significant prognostic factors of an unsuccessful upper-extremity revascularization, while age was the only patient characteristic that was associated with this outcome. In particular, total amputation type and avulsion and crush injury mechanisms yielded a higher risk of unsuccessful revascularization. We recommend considering this information when making decisions regarding the treatment of upper-extremity amputation injuries.

Level of evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Fig. 1

Regression analysis of associations between independent variables and unsuccessful revascularization. The Wald test was used to assess the relative importance of each independent variable, with higher Wald test values indicating a stronger association with the likelihood of unsuccessful revascularization. On this plot, the Wald test assessed the overall significance of variables and tested for nonlinear associations. Χ² represents the Wald chi-square (square of [coefficient estimate/standard error] value) and Χ² – df represents the Wald chi-square value minus the degrees of freedom of the coefficient. Amputation type was defined as subtotal amputation (some tissue, for example, a strip of skin or a tendon, remains in continuity) or total amputation (all structures and tissue are separated). Injury mechanisms were classified as follows: cut (by a sharp edge or cutting blade), crush (caused by blunt trauma), and avulsion (amputation caused by a pulling force).

Fig. 2

Nonlinear association between the age variable and unsuccessful revascularization, adjusted for sex, diabetes, smoking, tissue loss before treatment (number of lost joints), amputation type, and injury mechanism. The age variable was modeled using a restricted cubic spline function with 4 default knots (quantiles: 0.05, 0.35, 0.65, and 0.95, which correspond to 12, 43, 57, and 71 years, respectively). Higher log odds values are indicative of an increased probability of failure. The gray area indicates the 95% confidence interval.

Fig. 3

Nonlinear association between the variable of tissue loss before treatment (number of lost joints) and unsuccessful revascularization, adjusted for sex, diabetes, smoking, age, amputation type, and injury mechanism. The variable of tissue loss before treatment was modeled using a restricted cubic spline function with 3 default knots (quantiles: 0.10, 0.50, and 0.90, which correspond to 1, 4, and 14 lost joints, respectively). Higher log odds values are indicative of an increased probability of unsuccessful revascularization. The gray area indicates the 95% confidence interval.

Fig. 4

The receiver operating characteristic (ROC) curve of the regression model represents the association between the true-positive (sensitivity) and the false-positive (1– specificity) ratios indicating the regression model’s discriminatory power to predict failure of the operation. The true-positive ratio (sensitivity) is the ratio of correctly predicted positive observations to the total actual positives. The false-positive ratio (1– specificity) is the ratio of incorrectly predicted negative observations to the total actual negatives. The dashed diagonal line represents an area under the curve (AUC) value of 0.5, indicating a predictive performance no better than chance.