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. 2020 Nov 26;6(4):945-953.
doi: 10.1016/j.artd.2020.09.011. eCollection 2020 Dec.

Lewinnek Safe Zone References are Frequently Misquoted

Aonnicha Burapachaisri  1 , Ameer Elbuluk  2 , Edem Abotsi  1 , Jim Pierrepont  3 , Seth A Jerabek  2 , Aaron J Buckland  1 , Jonathan M Vigdorchik  2
Affiliations

Lewinnek Safe Zone References are Frequently Misquoted

Aonnicha Burapachaisri et al. Arthroplast Today. .

Abstract

Background: Optimal acetabular component orientation in total hip arthroplasty (THA) is a necessity in achieving a stable implant. Although there has been considerable debate in the literature concerning the safe zone, to date, there has not been any review to determine if these references are consistent with the definition applied by Lewinnek et al. in 1978. Therefore, this article aims to examine the available literature in the PubMed database to determine how often a correct reference to the safe zone as defined by Lewinnek was applied to discussions regarding THA.

Methods: A search for literature in the PubMed database was performed for articles from 1978 to 2019. Search criteria included terms 'Lewinnek,' 'safe zone,' and 'total hip arthroplasty.' Exclusions included abstract-only articles, non-English articles, articles unrelated to THA, and those lacking full content.

Results: A review of literature yielded 147 articles for inclusion. Overall, only 11% (17) cited the Lewinnek article correctly. Forty-five percent (66) of articles referenced measurements in the supine position, 18% (26) referenced other positions, and 37% (55) did not specify. Nineteen percent (28) reported measurements of the acetabular cup orthogonal to the anterior pelvic plane, while 73% (108) did not, and 7% (11) did not specify. Twenty-three percent (34) measured from computed tomography scans instead of other methods.

Conclusions: In the discussion of the safe zone regarding THA, only 11% of articles listed are consistent with the definition established by Lewinnek. This warrants further investigation into a consistent application of the term and its implications for THA implant stability and dislocation rates.

Keywords: Anterior pelvic plane; Anteversion; Inclination; Lewinnek; Safe zone; Total hip arthroplasty.

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Figures

Figure 1
Figure 1
Articles that correctly and articles that incorrectly referenced the Lewinnek safe zone are shown. A Lewinnek safe zone reference was considered correct if an article correctly referenced all the following criteria: article referenced in the supine position, acetabular cup referenced orthogonal to the APP, measurements using radiographs, and measurements using CT scans. Articles were considered incorrect overall if at least one of these criteria was incorrect or not mentioned.
See this image and copyright information in PMC

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