Fig. 4From: One-hole split endoscope versus unilateral biportal endoscopy for lumbar spinal stenosis: a retrospective propensity score studySchematic of imaging measurements. A The measurement of dural sac cross-sectional area (DCSA); B, C The measurement of range of motion (ROM) and sagittal translation (ST) in hyperextension and hyperflexion; ROM = a1–a2; ST =|b1–b2|Back to article page