The sacroiliac joint (SIJ) exists between the sacrum and pelvic bones. The sacrum is wedged shaped and supports the entire spine. Because of its shape, when the downward pressure of the spine is increased the sacrum is further ‘wedged’ down between the pelvic bones. This mechanical wedge works because of the many strong ligaments that stop the pelvic bones from moving apart.
However, a common problem with the sacroiliac joint exists for many pregnant ladies. Hormonal changes make their ligaments more stretchy. This laxity in ligaments can allow the sacrum to move slightly out of position and potentially generate a sheering force, which in turn can initiate a pain response. The pain may be unwelcome but the hormonal changes are essential as their function is to intentionally relax ligaments to help the pelvic bones move apart and increase the birth canal.
Other sacroiliac problems can arise from trauma and inflammatory disease. It is however important to reflect on the non-pregnant persons natural stability around this joint and therefore when a mechanical strain is placed on the back, the spinal segments and hip joints will almost always move first.
Any problems with the hip joints and the lumbar spine can therefore never be excluded from any potential SIJ dysfunction.
For a person to attain their best mechanical pelvic function, they will need to include rehabilitation that has focus on lower limb alignment, leg length, hip movement, spinal posture and both gluteal muscle strength and core stability.
If the clinical presentation indicates excessive inflammation then guided injection therapy is also a treatment option.