An Anatomical Cadaveric Demonstration of an Ultrasound-Guided Fascial Plane Injection Pathway in the Deep Gluteal Space

Background: Deep gluteal syndrome (DGS) has traditionally been attributed to sciatic nerve entrapment within the deep gluteal space. However, increasing evidence suggests that enthesopathy and soft tissue pathology of the short external rotators may also contribute to its pathogenesis. Conventional ultrasound-guided interventions primarily target the sciatic nerve through perineural hydrodissection (HD), which may not address enthesis-related pathology. However, the anatomical feasibility of delivering injectate along the deep gluteal fascial plane has not yet been investigated in cadaveric studies. Methods: This cadaveric anatomical demonstration evaluated whether an ultrasound-guided fascial plane injection within the deep gluteal space could simultaneously reach the enthesis of the short external rotators and the region of the sciatic nerve. Ultrasound scanning protocols were first demonstrated in a healthy volunteer to establish anatomical orientation for the injection pathway. Injection experiments were then performed in a fresh-frozen cadaver (83-year-old male) using a cranial-to-caudal in-plane approach. Ten milliliters of methylene blue dye was injected along the fascial plane overlying the short external rotator enthesis, followed by layer-by-layer cadaveric dissection to assess dye distribution. Results: Cadaveric dissection demonstrated that methylene blue injected along the deep gluteal fascial plane extended to the enthesis of the short external rotators and spread toward the surface of the sciatic nerve. Comparable distribution patterns were observed in both hips. These findings suggest that a single ultrasound-guided fascial plane injection trajectory may anatomically access both the enthesis region and the adjacent sciatic nerve within the deep gluteal space. Conclusions: Ultrasound-guided fascial plane HD in the deep gluteal space provides an anatomical pathway that can simultaneously access the enthesis of the short external rotators and the region of the sciatic nerve. This approach may represent a potential anatomical basis for a fascial plane-based intervention strategy in DGS. Further studies are required to evaluate in vivo behavior and clinical effectiveness.