BACKGROUND:
Dislocation remains one of the most common complications after total hip arthroplasty. Constrained acetabular liners were developed to address the problem of recurrent instability. They have been in clinical use since the mid 1980s and function by capturing the femoral head.

METHOD:
The aim of this review is to highlight the mechanism of action, development, and advances in constrained liner design, together with an emphasis on the modes of failure and the authors' opinion on the current indications for the use of these implants.

RESULTS:
A systematic review of the literature summarizes the current body of published evidence on the results of constrained liners. Overall, at best level III evidence is available. In the 38 studies included, this study considered a total of 2852 constrained liners with a mean follow-up 4.3 years (range 0.8-20 years), which had a mean dislocation and/or constrained failure rate of 11.4% (95% confidence interval 10.3-12.6).

CONCLUSION:
Constrained acetabular liners remain an important option in the armamentarium of the revision hip surgeon. At this point in time with current designs and published results, they should remain a salvage device. The implantation of a constrained liner should be considered when all other factors related to the total hip arthroplasty have been optimized, especially component malposition.





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