Q Since having my last baby I have experienced a burning feeling down through my sacro-iliac joint. Occasionally I feel an ache deep in my buttock. I’ve tried osteopaths, physiotherapy with ultrasound and now acupuncture, and I would appreciate some advice from you. I had this baby, like my first, by Caesarean section.

A This sort of pain is often known as the ‘lumbo-pelvic conundrum’. This is because pain which appears to be coming from the sacro-iliac joint at the back of the pelvis can arise from the joint itself, the joints of the low lumbar vertebra, nerve roots emerging from these vertebra, and from muscles and the tendinous tissue through which they attach into the back of the pelvis.

In addition, the sciatic nerve, which is the largest nerve in the leg and which passes down the back of the thigh, emerges through the back of the pelvis under some muscles which often become tight in runners.

An added complication can be the after-effects of pregnancy and childbirth. In the last three months of pregnancy, the baby grows substantially, filling the relatively small space in the abdomen between the bladder at the front and the spinal column at the back. This can lead to excessive pressure on the structures at the front and sides of the low lumbar spine, leading to persistent problems with discomfort and pain after delivery. During the latter stages of pregnancy and particularly delivery, the sacro-iliac joints and ligaments are stretched, and it is thought that this can lead to a misfit at the joints after the birth. However, in the case of your Caesarean section, this final stretch is avoided.

From the symptoms that you describe, it seems likely that tension in the sciatic nerve has a role in producing your pain. A chartered physiotherapist should be able to assess the mobility of the sciatic nerve. It is quite common for impingement of the nerve to occur in the buttock under a little muscle called the piriformis, which rotates the hip outwards and can become tight during pregnancy. Tension in the nerve can be corrected through simple exercise and some manipulation. My advice would be to visit a chartered physiotherapist with specialist manipulative training, who will be able to help you with this type of problem. You can be shown some simple exercises to perform regularly yourself, as well as specific muscle-stretching exercises to ensure mobility around the low back and pelvic areas. Although you have tried osteopathy and physiotherapy to date, it may be that the problem still hasn’t been identified accurately, so don’t give up yet.

—Judith Pitt-Brooke, chartered physiotherapist at the East Midlands Physiotherapy Clinic and On Trak Movement Analysis Centre