Summary
Objectives: To compare the accuracy and distribution of injectate for cranial (CR) and caudomedial
(CM) ultrasound-guided injections of equine sacroiliac joints.
Methods: Both sacroiliac joints from 10 lumbo sacropelvic specimens were injected using cranial
parasagittal (CR; curved 18 gauge, 25 cm spinal needles) and caudomedial (CM; straight
18 gauge, 15 cm spinal needles) ultrasound-guided approaches. Injectate consisted
of 4 ml iodinated contrast and 2 ml methylene blue. Computed tomo-graphical (CT) scans
were performed before and after injections. Time for needle guidance and repositioning
attempts were recorded. The CT sequences were analysed for accuracy and distribution
of contrast.
Results: Intra-articular contrast was detected in sacroiliac joints following 15/40 injections.
The CR and CM approaches deposited injectate ≤ 2 cm from sacroiliac joint margins
following 17/20 and 20/20 injections, respectively. Median distance of closest contrast
to the sacroiliac joint was 0.4 cm (interquartile range [IQR]: 1.5 cm) for CR approaches
and 0.6 cm (IQR: 0.95 cm) for CM approaches. Cranial injections resulted in injectate
contacting lumbosacral intertrans-verse joints 15/20 times. Caudomedial injections
were perivascular 16/20 times.
Limitations: Safety and efficacy could not be established.
Clinical relevance: Cranial and CM ultra-sound-guided injections targeting sacroiliac joints were very
accurate for periarticular injection, but accuracy was poor for intra- articular injection.
Injectate was frequently found in contact with interosseous sacroiliac ligaments,
as well as neurovascular and synovial structures in close vicinity of sacroiliac joints.
Keywords
Ultrasound-guided - horse - sacroiliac - lumbosacral - computed tomography