Outcomes of amputation and limb salvage in combat injuries: Does level of injury matter? A secondary analysis of Military Extremity Trauma Amputation/Limb Salvage (METALS) study data

Background: The Lower Extremity Assessment Project (LEAP) and Military Extremity Trauma Amputation/Limb Salvage Study (METALS) reported conflicting results with respect to severe lower extremity injuries treated with limb salvage versus amputation. The LEAP study reported no difference between amputation and limb salvage groups, while the METALS study reported improved outcomes with amputation. The purpose of this study was to re-evaluate the METALS data to determine whether the ankle/hindfoot injuries were the main driver of the results of improved outcome with amputation. Methods: This is a retrospective secondary analysis of METALS data including military personnel deployed to Afghanistan or Iraq between 2003 and 2007 with severe lower extremity combat injuries. METALS patients with a unilateral transtibial amputation, or unilateral limb salvage of a qualifying injury distal to the femoral condyles were included. Amputation patients were compared to two separate limb salvage groups: severe ankle/hindfoot injuries (ie. ankle/hindfoot salvage group) versus mid/proximal tibia injuries (ie proximal limb salvage group). Short Musculoskeletal Function Assessment (SMFA) scores were compared between groups. Multivariable regression models compared outcomes across treatment groups, adjusting for age, race/ethnicity, time from injury, combat experience, and social support. Results: 161 patients were included: 60 amputation, 41 ankle/hindfoot salvage, 62 proximal limb salvage. Amputation patients reported better function (lower SMFA scores) compared to both limb salvage groups for the daily activities sub-score. Amputation patients reported better function than proximal salvage patients in all domains. There was no difference in SMFA scores between the two limb salvage groups. On adjusted analysis, amputation patients reported significantly better function for total dysfunction and daily activity scores than either limb salvage group. Conclusions: This secondary analysis of the METALS data reveals that amputation resulted in superior functional outcomes compared to limb salvage after both ankle/hindfoot and more proximal tibial combat related injuries. This study highlights differences between civilian and military traumatic extremity injuries and indicates that treatment results cannot be generalized between populations. Level of evidence: Prognostic Level II