Case reportA 59 year old woman came to us complaining of lower back pain for four months with no obvious precipitating cause. On closer questioning, she reported that she had lower back pain for years, but this had deteriorated only recently.In the preceding four months, she had hardly been able to lie flat and had to sleep in the sitting position. The pain was worse when she tried to stand from a sitting or lying position. The pain radiated down both legs, worse on the right. She could hardly walk without pain and at the time could only manage a few yards, using a stick. Her sleep was disturbed. No subjective neurological symptoms in the lower limbs, or bowel or bladder disturbances were reported. She had also been due to be investigated for rectal bleeding by barium enema, but could not endure this because of the severity of her back pain. In her past medical history, she had a breast lump in 1991, a total hysterectomy and bilateral salpingo-oophorectomy in 1993, and had suffered from depression.Four months before coming to us, she had undergone a sacrocolpopexy using a Prolene mesh attaching the vaginal vault to the sacral promontory.On examination, she could hardly walk without a stick, and did so stooping forward with a rather waddling gait. She stood with significant pelvic obliquity towards the right, her trunk stooping forward. She was exquisitely tender across the lumbosacral junction with maximum tenderness over her buttock. Spinal movements were grossly restricted in all directions by pain. Straight leg raising on the left was 70j, and on the right 30j -limited by back pain. The sciatic stretch test was positive on the right. Other tension signs were negative. No objective evidence of myelopathy or radiculopathy in the lower limbs could be found.Investigations revealed a high concentration of alkaline phosphatase, gamma-glutamyl transferase and erythrocyte sedimentation rate. Magnetic resonance imaging showed significant spondylodiscitis of L5/S1 with bony destruction of the lower part of L5 and the dome of the sacrum.This was treated operatively by an anterior and a posterior approach. The anterior approach was via a transverse incision through the previous scar and the parietal peritoneum was found adherent to the retroperitoneal space. A huge cavity was found engulfing some mesh material and the staples used for the sacrocolpopexy (Fig. 1). The cavity extended into the lower part of L5 and the dome of the sacrum. This was curetted to healthy bone and a tri-cortical bone graft (harvested from the iliac crest) was fitted under compression (Fig. 2). The patient was turned prone, and posterior stabilisation using edit pedicle screws from L5 to S1 was performed. Post-operatively, she received a threemonth course of antibiotics and eventually made a full recovery.