Lumbosacral plexus and sciatic nerve injury following acetabular fracture: predictive value of CT bony features and perineural hematoma.

Abstract

Sciatic nerve injury is a rare, devastating complication of acetabular fracture. assess CT predictive value (bony features and perineural hematoma) for sciatic nerve injury following acetabular fracture. IRB-approved retrospective study (n = 471) from 2011 to 2022. Single rater evaluated each case for Judet-Letournel subtype, joint congruence loss, and posterior displacement. Three raters assessed perineural hematoma in zones 1-3: obturator internus, piriformis, and posterior thigh. EMG/NCS confirmed sciatic injury in 20 cases. Sensitivity, specificity, PPV, NPV, OR, and accuracy (AUC) were computed for each marker. Intra- and inter-rater reliability was calculated. Sciatic injury was most frequent in associated both column (8.0%) and transverse family (5.9%) fractures. Sensitivity and specificity of fracture features on sciatic injury were both column involvement (0.85 [17/20], 0.31 [140/451]), congruence loss (0.90 [18/20], 0.36 [163/451]), and posterior displacement (0.70 [14/20], 0.54 [244/451]). Joint congruence loss (OR 5.08, p = 0.016) and posteriorly displaced fragment (OR = 2.74, p = 0.04) were statistically significant (p < 0.05). For hematoma, sensitivity and specificity were zone 1, 0.65-0.80 [13/20-16/20] and 0.30-0.36 [136/451-161/451]; zone 2, 0.60-0.80 [12/20-16/20] and 0.39-0.57 [176/451-255/451]; and zone 3, 0.15-0.25 [3/20-5/20] and 0.69-0.86 [312/451-388/451]. AUC values were zone 1, 0.65-0.71 (satisfactory-to-good); zone 2, 0.69-0.71; and zone 3, 0.48-0.61 (poor-to-satisfactory). Values were significant in zones 1 and 2. Intra-rater reliability (Gwet's AC2) was almost perfect in zone 1 (0.86-0.87), moderate to almost perfect in zones 2-3 (0.47-0.90). Inter-rater agreement (Gwet's AC2) in zones 1-3 was 0.73 (substantial), 0.49 (moderate), and 0.50. We found three statistically significant predictors of sciatic nerve injury following acetabular fracture: joint congruence loss, posteriorly displaced bone fragment, and perineural hematoma at the level of (a) obturator internus and (b) piriformis. Rater agreement for perineural hematoma was excellent for zone 1.