Cobalt-chromium head wear following revision hip arthroplasty performed after ceramic fracture—a case report

In February 2000, a 59-year-old woman with bilateral congenital hip dislocation underwent cement-less total hip arthroplasty with alumina-on-alumina bearings on the right side. The implants used were a ceramic sandwich cup, a titanium alloy stem, and a 28-mm alumina ceramic head (Kyocera, Kyoto, Japan). The sandwich cup consisted of an alumina ceramic liner housed in an ultra-high molecular weight polyethylene shell that was held in a titanium alloy metal shell.

The patient had good clinical results until July 2001, when she noticed a crepitus deep in the right hip during motion. Radiographs revealed a comminuted fracture of the ceramic liner. The patient underwent revision surgery in August 2001. 9 large pieces of the ceramic liner and many small fragments were found along with black-stained peri-prosthetic tissues. The cause of the ceramic liner fracture may be the concentration of stress at the rim of the thin ceramic liner, and the steep cup placement may have enhanced the risk of liner fracture (Hasegawa et al. 2003). The ceramic fragments were removed, and synovectomy that was as complete as possible was performed. When we removed the polyethylene liner and the screws of the metal shell, we observed that the shell was not loose, and therefore it was not removed. The head was removed. The femoral stem was not loose, and the taper was undamaged macroscopically. After the joint was lavaged with a pulsatile lavage system (Zimmer, Warsaw, IN), a modular polyethylene liner without a ceramic liner (inner diameter, 26 mm) was implanted. The ceramic head was replaced with a 26-mm cobalt-chromium head (Kyocera).

The patient returned to full activity without discomfort in the hip. About 2 years later, in September 2003, a radiograph taken at another institution revealed a radio-dense shadow around the stem neck (Figure 1). The patient underwent a second revision at our institution in May 2004. A black-colored effusion filled the pseudocapsule. We found considerable black staining in the peri-prosthetic tissues. The black-stained granulation was excised. The cobalt-chromium femoral head was severely worn (Figure 2). Alumina particles, ranging in size from 1 to 2 mm, were found loose within the pseudocapsule. The polyethylene liner was embedded with small particles. We removed the acetabular metal shell, although well-fixed, and replaced it with a new cementless metal shell. The well-fixed femoral stem was revised because it was not compatible with a ceramic component, and given the circumstances, another cobalt-chromium head would be likely to fail. A polyethylene liner was inserted into the metal shell and a new alumina head was placed on the new taper.