We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken.

All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision.

We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause.

Acute colonic pseudo-obstruction is a poorly recognised and potentially fatal complication of hip surgery.

Between 1991 and 1994 six patients were observed who required laparotomy after failure of medical management. In three the indication was signs of peritonism, while in the other three exploration was required to exclude segmental ischaemia and to decompress the bowel. In all, there was no evidence of mechanical obstruction.

Patients having total hip replacement are at risk of developing pseudo-obstruction due to their age, comorbidity, high doses of analgesics and the nature of the operation. If postoperative ileus persists for more than 48 hours acute colonic pseudo-obstruction should be suspected and confirmed by plain radiography. Prompt recognition and treatment with early referral to a colorectal unit are indicated. Laparotomy appears to carry less risk than that for patients with idiopathic pseudo-obstruction, but should be performed only if colonic ischaemia is suspected.