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Lewinnek “safe zone” for THA box is dead according to Larry Dorr and John J. Callaghan

January 15 2019

Death of the Lewinnek “Safe Zone”

Forty years ago, Lewinnek et al [1] published their work entitled “Dislocation after Total Hip-Replacement Arthroplasties”. The authors suggested “that there is a relatively safe range of orientations for the cup. A number of such ranges were investigated,” and the range of 40° ± 10° of lateral opening and 15° ± 10° of anteversion “proved most satisfactory.”

In that article, the authors published a figure (Fig. 4) [1] of a scatter diagram of the orientation of the acetabular components studied with a superimposed square depicting the area, in which the “most satisfactory” cup position was depicted.

Over the last 4 decades, this has been referred to as the “Lewinnek safe zone” for cup placement in total hip arthroplasty (THA). The article has been cited in close to 2000 publications in the English language [2].

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