The iliolumbar ligament runs from the lowest lumbar vertebra to parts of the pelvis (the iliac wings). It is an incredibly strong ligament, but can still sometimes get strained, usually with a forceful twisting or bending injury.
This condition causes pain deep in the upper buttock area on one side. It is often worse with bending, arching or twisting the back.
If you think you have this injury it is well worth getting it checked out by Mr Willis-Owen. In the mean time you should avoid any aggravating activities with may prolong the problem.
Treatment involves first confirming the diagnosis, then establishing the underlying cause. Options may include activity modification, physiotherapy, orthotics and anti inflammatories. Rarely an injection is needed.