Failure analysis of a ceramic bearing acetabular component

• Published in: Journal of bone and joint surgery. American volume 2007-02, Vol.89A (2), p.367-375
• Main Authors: POGGIE, Robert A, TURGEON, Thomas R, COUTTS, Richard D
• Format: Article
• Language: English
• Subjects: Acetabulum - surgery; Adult; Biological and medical sciences; Biomechanical Phenomena; Ceramics; Diseases of the osteoarticular system; Equipment Failure Analysis; Female; Finite Element Analysis; Hip Prosthesis; Humans; Injuries of the limb. Injuries of the spine; Logistic Models; Male; Medical sciences; Middle Aged; Orthopedic surgery; Prospective Studies; Prosthesis Design; Randomized Controlled Trials as Topic; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Traumas. Diseases due to physical agents
• ISSN: 0021-9355; 1535-1386
• DOI: 10.2106/00004623-200702000-00019

Alternative bearings have been explored in an attempt to improve the longevity of total hip prostheses. A Food and Drug Administration (FDA)-approved clinical study of a nonmodular acetabular component consisting of a porous metal shell, compression-molded polyethylene, and a ceramic liner inlay was discontinued following reports of early failures. Between October 1999 and January 2003, 429 patients were enrolled in a prospective study to evaluate a cementless ceramic-on-ceramic total hip arthroplasty design (Hedrocel ceramic bearing cup; Implex, Allendale, New Jersey). Two hundred and eighty-two patients (315 hips) were treated with the experimental acetabular implant and 147 patients (157 hips) were treated with an acetabular implant that consisted of the same porous shell but an allpolyethylene liner. Clinical data including a Harris hip score and responses to the Short Form-12 (SF-12) health survey were collected preoperatively and at twelve and twenty-four months postoperatively. Serial radiographs were made preoperatively; at six weeks, three months, six months, and twelve months postoperatively; and annually thereafter. Retrieval analysis was performed on all failed explanted components. Failure was defined as fracture or displacement of the ceramic liner out of the acetabular component. In addition, biomechanical testing was performed on unimplanted acetabular components and mechanically altered cups in an effort to recreate the mechanisms of failure. Finite element analysis was used to estimate stress and strain within the ceramic liner under extreme physiologic loading conditions. The ceramic liner failed in fourteen of the 315 experimental acetabular components; all of the failures were at the ceramic-polyethylene interface. Patients with a body weight of >91 kg had a 4.76 times greater odds of the ceramic liner failing than those who weighed < or =91 kg. Retrieval analysis demonstrated stripe and rim wear with evidence of adhesive wear, indicating a potentially high-friction interaction at the articulation. Finite element analysis demonstrated that the forces on the ceramic liner in cups subjected to extreme loading conditions were insufficient to cause fracture. Biomechanical testing was unable to reproduce an initial ceramic liner displacement in vitro; however, when the ceramic liner was forcibly displaced prior to biomechanical testing, complete displacement and eventual fracture of the ceramic liner resulted. We hypothesized that the combi