The Sacroiliac Joint

The Sacroiliac Joint (SIJ) is crucial for the transfer of power from the hind legs to the rest of the body, making it essential for almost all equine movements.

Anatomy of the Sacroiliac Joint

The SIJ consists of the sacrum (the lower part of the spine) and the ilium (part of the pelvic bone). It is a strong, weight-bearing joint with movement in several planes: flexion and extension, gliding, and axial rotation. It is supported by a strong network of ligaments and muscles.

The SIJ acts as a shock absorber and stabiliser during movement and is responsible for the transmission of forces from the hind end forward through the spine.

SIJ Disease in Horses

The clinical signs of SIJ disease in horses can be subtle and can include varying symptoms:

• Pain or discomfort over the SIJ

• Gait asymmetries

• Difficulty with certain movements that require increased loading on the hind end (such as taking off at jumps, pirouettes, or even just sitting back in the canter),

• Asymmetry in the hindquarters

• Behavioral changes due to pain, such as reluctance to move forward or be saddled

Diagnosing SIJ Disease

Diagnosing SIJ disease usually involves a combination of a physical examination, learning about the history of the animal, and imaging techniques.

Imaging modalities in the pelvis are limited due to the size of horses. The 2 main modalities are:

• Scintigraphy: which is able to pick up bone turnover and therefore suspected arthritic change in the lumbosacral or sacroiliac joints,

• Ultrasound: this is performed via a rectal ultrasound, just like a mare scan would be, except the probe faces up to the joints of the pelvis instead of down to the reproductive organs. Ultrasonography is fairly limited in deep tissue information however as ultrasound waves can't penetrate bone. Therefore when we see changes at the joints it is thought that these are likely the 'tip of the iceberg'.

  Equally, if no changes are seen, this does not completely rule out pain in this region. This is where complimenting ultrasonography with scintigraphy may be valuable.

Below are a series of ultrasound images of what we look for in regards to joint pathology. When scanning the pelvis we are able to look for:

• joint disease of the lumbosacral and sacroiliac joints,

• nerve root pathology,

• pelvic fractures,

• insertional lesions of the psoas minor tendon and rectus abdominus.

Reference image of a normal SI joint. The blue arrow is pointing to the wing of the sacrum and the red  arrow is pointing to the ilium. The space in between (green arrow) is the SIJ.

- there is moderated to significant remodelling to the border of the wing of the ilium (red arrows) compared to the reference image.

Treating Lumbosacral and Sacroiliac Joint Disease in Horses

Treatment of pelvic disease is multifaceted and has a large focus on rehabilitation and strengthening of the core and the muscles of the pelvic girdle.

Treatment options may include:

• Ultrasound guided deep injections of the pelvis with corticosteroids to help reduce inflammation. Ultrasound guided placement of the needle increases precision in treatment by making sure the needle lands adjacent to the joint.

• Rehabilitation exercises to strengthen muscles of the spine, core, hindquarters

• Chiropractic adjustments

• Shock Wave Therapy

If you suspect your horse may be experiencing issues related to the sacropelvic region, contact us to arrange a comprehensive assessment. We are dedicated to providing precise diagnostics and tailored management plans to optimize your horse's comfort and performance.