A constrained liner cemented into a secure cementless acetabular shell.
BACKGROUND
Constrained acetabular components have been used to treat hips with recurrent instability following total hip arthroplasty and hips that demonstrate instability during revision surgery. In such hips, when a secure cementless acetabular shell is present, the surgeon can cement a constrained liner into the existing shell. The purpose of this study was to evaluate the clinical and radiographic outcome of this technique with use of a tripolar constrained liner that was cemented into a well-fixed cementless acetabular shell.


METHODS
Between 1988 and 2000, constrained liners were cemented into thirty-one well-fixed cementless acetabular shells at three centers. The average age of the patients at the time of the index surgery was 72.1 years, and the indications for the procedure were recurrent hip instability in sixteen hips and intraoperative instability in fifteen hips. The patients were evaluated with respect to the clinical outcome and radiographic evidence of shell loosening and osteolysis.


RESULTS
At an average duration of follow-up of 3.9 years, twenty-nine liners (94%) were securely fixed in the cementless shells and two constrained liners had failed. One liner failed because it separated from the cement, and one failed because of fracture of the capturing mechanism. Both hips were successfully revised with another cemented tripolar constrained liner. No acetabular component demonstrated radiographic evidence of progressive loosening or osteolysis.


CONCLUSIONS
A constrained tripolar liner cemented into a secure, well-positioned cementless acetabular shell provides stability and durability at short-term follow-up. Careful attention to the preparation of the liner, the sizing of the component, and the cementing technique are likely to reduce the failure of this construct, which can be used for difficult cases of total hip instability.
Callaghan
John J
JJ
Department of Orthopaedic Surgery, University of Iowa Health Care, 200 Hawkins Drive, Iowa City, IA 52242, USA. john-callaghan@uiowa.edu
Parvizi
Javad
J
Novak
Clifford C
CC
Bremner
Barron
B
Shrader
Wade
W
Lewallen
David G
DG
Johnston
Richard C
RC
Goetz
Devon D
DD
D000077:Acetabulum; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001843:Bone Cements; D005260:Female; D006621:Hip Joint; D006622:Hip Prosthesis; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012086:Reoperation; D016896:Treatment Outcome
D001843:Bone Cements