Sacroiliitis, i.e. inflammation of the sacroiliac joint(s), is a relatively common cause of low back pain. This joint is formed from the junction of the sacrum (low back/buttock area) and ilium (part of your pelvis). Pain and inflammation of the joint is usually related to malalignment and/or abnormal rotation of the joint. In addition, it can be related to other disorders that cause inflammation of the spine. It is a relatively common disorder that is often overlooked as a possible pain generator. It is more common in women and in younger to middle aged adults. The pain typically feels deep and achy and worse with pressing over the joint itself. Factors that can make the pain worse are prolonged standing and climbing up steps. Pain can radiate to your buttock(s) and hip(s) all the way down to your knee(s). If the pain goes past your knees, you may have pain coming from the nerves in your low back (radiculopathy).
Despite the fact that this condition is common, it is likely one of the most underdiagnosed conditions causing mechanical low back pain. Seeing a spine specialist to determine if this is a significant component to your pain is crucial to not missing this diagnosis. X-rays of the area typically are normal. The best way to diagnose whether or not this joint is causing your low back pain is to numb the joint. If injecting local anesthetic into the joint resolves your pain, then this confirms the diagnosis of sacroiliitis. This specific condition typically is not cured by surgery but significant pain relief can still be obtained with interventional therapies. If this is an acute pain, the pain may resolve after conventional therapies such as anti-inflammatories. However, if your pain persists or is a chronic problem, steroid injections within the joint (see sacroiliac joint injection) may be beneficial to decrease the inflammation in joint thereby providing pain relief. If these injections do not provide relief beyond several months, you may be candidate for other interventional therapies that can provide, on average, >50% relief for 6 months. This is called sacroiliac denervation which is similar to what can done to the joints of your lower back (see lumbar radiofrequency denervation). As with any pain condition, having the correct diagnosis early on in the course of your pain is crucial in not only giving you the most appropriate treatment but also decreasing the likelihood of this becoming a lifelong problem.