Ultrasonographic abnormalities detected in the sacroiliac area in twenty cases of upper hindlimb lameness

REASONS FOR PERFORMING STUDY: The pelvis is covered with extensive musculature and often presents a challenge in diagnostic imaging. Ultrasonography provides diagnostic information about soft tissue, articular cartilage and bone surfaces, although little information exists about the normal ultrasonographic appearance of the equine sacroiliac region. OBJECTIVES: To determine the clinical applicability of ultrasonographic examination in horses with sacroiliac pain. METHODS: Horses presented to the University of Minnesota Veterinary Teaching Hospital for hindlimb lameness were evaluated and lower limb lameness was ruled out with examination and local anaesthesia. Twenty cases were diagnosed with sacroiliac pain, characterised by response to palpation over the tuber sacrale. Seven of the 20 had visible asymmetry of the tuber sacrale. Ultrasonography was performed percutaneously and per rectum. Structures imaged were measured and compared to normal reference measurements. Other methods used to confirm diagnoses included thermography, scintigraphy and radiology. RESULTS: All 20 cases with sacroiliac pain showed ultrasonographic abnormalities of the sacroiliac area. Abnormalities were detected in the dorsal sacroiliac ligaments. Ligament size was significantly different from the normal ranges (P < 0.01). Malalignment of the sacroiliac area and sacral fractures were also imaged. CONCLUSIONS: Ultrasonography of the sacroiliac region aided diagnosis of ligament damage and displacement of bone surfaces; and may aid in monitoring the progression of healing. Potential relevance: Diagnostic ultrasound is readily available to most practitioners. Therefore the findings of this study show that diagnosis of sacroiliac injuries is possible in the field.