title: Early failure mechanisms of constrained tripolar acetabular sockets used in revision total hip arthroplasty.
abstract: Fifty-eight patients received an Osteonics constrained acetabular implant for recurrent instability (46), girdlestone reimplant (8), correction of leg lengthening (3), and periprosthetic fracture (1). The constrained liner was inserted into a cementless shell (49), cemented into a pre-existing cementless shell (6), cemented into a cage (2), and cemented directly into the acetabular bone (1). Eight patients (13.8%) required reoperation for failure of the constrained implant. Type I failure (bone-prosthesis interface) occurred in 3 cases. Two cementless shells became loose, and in 1 patient, the constrained liner was cemented into an acetabular cage, which then failed by pivoting laterally about the superior fixation screws. Type II failure (liner locking mechanism) occurred in 2 cases. Type III failure (femoral head locking mechanism) occurred in 3 patients. Seven of the 8 failures occurred in patients with recurrent instability. Constrained liners are an effective method for treatment during revision total hip arthroplasty but should be used in select cases only.
authors.affiliation: Orthopaedic Surgery, Lancaster, Pennsylvania, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Cooke
authors.forename: William
authors.initials: W
authors.lastname: Hozack
authors.forename: Carlos
authors.initials: C
authors.lastname: Lavernia
authors.forename: Peter
authors.initials: P
authors.lastname: Sharkey
authors.forename: Shani
authors.initials: S
authors.lastname: Shastri
authors.forename: Richard H
authors.initials: RH
authors.lastname: Rothman
mesh_terms: D000077:Acetabulum; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D001847:Bone Diseases / Q000601:surgery; D019544:Equipment Failure Analysis; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D012086:Reoperation