Sciatic nerve atrophy as a risk factor for impaired wound healing in patients with chronic limb-threatening ischemia

Objective

Patients with chronic limb-threatening ischemia (CLTI) typically undergo revascularization as the standard treatment. However, some still require major amputations post-revascularization. Because revascularization is invasive and costly, avoiding it may benefit patients with low likelihoods of wound healing. The Global Vascular Guidelines suggest primary amputation for patients unsuited to revascularization. Although previous research has linked frailty to limb prognosis, skeletal and bone frailties impact survival rather than limb outcomes. This study examines the association between sciatic nerve atrophy and limb prognosis in patients with CLTI.

Methods

This single-center, retrospective study included patients with tissue loss CLTI who underwent successful revascularizations at Kyushu Medical Center (2015-2020). Sciatic nerve cross-sectional areas (CSAs) were measured using computed tomography scans above the bifurcation of the tibial and peroneal nerves. The CSA cutoff value for predicting wound healing was established using receiver operating characteristic analysis. Patients were grouped based on whether their CSA was larger (normal) or smaller (atrophy) than CSA cutoff value. Outcomes assessed included wound healing rates, amputation-free survival (AFS), and overall survival (OS).

Results

Among 188 patients (226 limbs), the mean sciatic nerve CSA was 27.5 ± 0.7 mm². A CSA cutoff of 23.6 mm² (area under the curve = 0.81; sensitivity = 0.85; specificity = 0.71) was identified. Patients were categorized into normal (n = 147) and atrophy (n = 79) groups. The atrophy group had higher rates of nonambulatory status (38% vs 23%; P = .029), ischemic heart disease (47% vs 28%; P = .008), cerebrovascular disease (50% vs 35%; P = .045), end-stage renal disease (55% vs 37%; P = .024), and lower serum albumin (3.3 ± 0.06 vs 3.6 ± 0.05; P = .001). Six-month wound healing rates were 87.3% in the normal group vs 27.3% in the atrophy group (P < .001). Three-year AFS was 59.3% in the normal group vs 20.0% in the atrophy group (P < .001), and 3-year OS was 71.3% vs 57.8% (P = .022). Factors associated with impaired wound healing included age (hazard ratio [HR], 1.01; P = .045), low serum albumin (HR, 1.80; P = .001), ischemic heart disease (HR, 1.75; P = .002), end-stage renal disease (HR, 1.71; P = .002), and sciatic nerve atrophy (HR, 5.21; P < .001). Multivariate analysis identified age (HR, 1.02; P = .012) and sciatic nerve atrophy (HR, 5.08; P < .001) as independent risk factors for impaired wound healing after revascularizations.

Conclusions

Sciatic nerve atrophy correlates with poorer wound healing, AFS, and OS in patients with CLTI. Sciatic nerve assessment may guide decisions regarding limb salvage eligibility.