Lower Extremity Free Tissue Transfer in the Setting of Severe Medial Arterial Calcification: Limb Salvage is Possible, But at What Cost?

Background: Medial arterial calcification (MAC) is emerging as a tool to predict adverse limb events, but its impacts on microsurgery is unknown. This study evaluates the impact of MAC on microsurgical limb salvage outcomes. Methods: Patients receiving lower extremity free tissue transfer (FTT) from 2011 to 2024 were reviewed. Radiographs were used to classify patients into absent, moderate, or severe MAC categories using the validated scoring by Ferraresi et al. Endpoints included (1) major amputation, (2) unscheduled surgical reinterventions, (3) postoperative revascularization, (4) major adverse limb events, defined as the composite of major amputation or surgical reintervention, and (5) survival. Results: Among 320 cases, 12 (3.8%) had moderate and 32 (10.0%) had severe MAC. Median follow-up was 22.2 months. On univariate analysis, patients with moderate and severe MAC demonstrated a significantly higher rates of flap complications (absent: 25.7% vs. moderate: 33.3% vs. severe: 56.3%; p=0.033), major adverse limb events (42.0% vs. 75.0% vs. 84.4%; p<0.001), surgical reintervention (absent: 41.3% vs. 66.7% vs. 81.3%; p<0.001), postoperative vascular intervention (6.9% vs. 8.3% vs. 31.3%; p<0.001), major amputation (12.0% vs. 25.0% vs. 31.3%; p=0.009), and 5-year mortality (5.4% vs. 8.3% vs. 18.8%; p<0.001). On multivariable analysis, severe MAC independently increased odds of major adverse limb events (p=0.009) and unscheduled reintervention (p=0.015). Conclusion: While microsurgical FTT can achieve limb salvage in patients with severe MAC, it is associated with significant morbidity, as over 80% will require additional surgical management. Microsurgeons should be made aware of MAC and its association with adverse events.