Retrospective cohort study from a single institution analyzing 206 dislocated THAs out of 9,784 primary cases (2003–2012), asking whether the Lewinnek safe zone — cup inclination 40° ± 10° and anteversion 15° ± 10° — reliably predicts freedom from dislocation in contemporary practice.
When a THA dislocates, don't assume the cup must be malpositioned — this study shows the majority of dislocations happen with radiographically 'perfect' cups, so your workup must also address femoral version, combined anteversion, soft tissue integrity, head size, and approach-specific factors.
Lewinnek targets remain a useful starting point but are not a guarantee: individualize your stability strategy rather than treating safe-zone compliance as sufficient.
Retrospective cohort study from a single institution analyzing 206 dislocated THAs out of 9,784 primary cases (2003–2012), asking whether the Lewinnek safe zone — cup inclination 40° ± 10° and anteversion 15° ± 10° — reliably predicts freedom from dislocation in contemporary practice.
When a THA dislocates, don't assume the cup must be malpositioned — this study shows the majority of dislocations happen with radiographically 'perfect' cups, so your workup must also address femoral version, combined anteversion, soft tissue integrity, head size, and approach-specific factors.
Lewinnek targets remain a useful starting point but are not a guarantee: individualize your stability strategy rather than treating safe-zone compliance as sufficient.