Ultrasound-guided periarticular injections of the sacroiliac region in horses: a cadaveric study.
Authors: Cousty M, Rossier Y, David F
Journal: Equine veterinary journal
Summary
# Editorial Summary: Ultrasound-guided sacroiliac injections in horses Sacroiliac injections in horses present a persistent clinical challenge because the joint's depth and anatomical variation make landmark-based techniques unreliable, prompting investigation into whether ultrasound guidance could improve needle placement precision. Using fourteen equine cadaveric pelves, researchers tested five distinct ultrasound-guided approaches with a 20 cm bent spinal needle, subsequently injecting 2 ml latex and measuring needle depth, proximity to the sacral articular margin, contact with the interosseous ligament, and proximity to neurovascular structures via dissection. The caudal approaches achieved significantly closer proximity to the joint (P = 0.02) but risked retroperitoneal placement, whilst the cranial and craniomedial approaches showed zero contact with neurovascular structures yet less frequent ligamentous contact; notably, 38 of 73 injections via cranial, craniomedial and medial approaches contacted the interosseous ligament compared to only one of 24 caudal injections (P = 0.01). For practitioners, this cadaveric evidence suggests that approach selection should be tailored to clinical objectives—caudal approaches prioritise articular proximity whilst cranial approaches minimise vascular risk—though clinical validation remains essential before confidently adopting these techniques in live horses where soft tissue elasticity and patient movement present additional variables.
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Practical Takeaways
- •Ultrasound-guided SI injections remove dependence on surface landmarks, improving accuracy in horses with deep joints or anatomical variations
- •Choose cranial/craniomedial approaches to avoid neurovascular structures if targeting SI ligament; use caudal approaches only if depositing medication closest to the joint is the priority and retroperitoneal leakage is acceptable
- •This cadaveric model demonstrates feasibility but clinical validation is needed before routine adoption—work with an experienced provider when implementing these techniques
Key Findings
- •Ultrasound guidance enabled needle placement under the iliac wing independent of external landmarks, with successful positioning in 13/14 injections
- •Caudal approaches deposited latex significantly closer to the sacral articular margin (P = 0.02) but risked retroperitoneal injection
- •Cranial and craniomedial approaches avoided neurovascular structures (0/47 contacts) but contacted the SI interosseous ligament less frequently than cranial/craniomedial/medial approaches combined (38/73, P = 0.01)
- •Contact with neurovascular structures emerging from the greater sciatic foramen was significantly more frequent with medial and caudal approaches (8/60, P = 0.005)