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. 2026 Mar;44(3):e70171.
doi: 10.1002/jor.70171.

A New Normative Zone for Acetabular Anteversion Positioning in ASD Patients

Marc Boutros  1 , Ayman Assi  1   2 , Bassel G Diebo  3 , Gilles Prince  1 , Mohammad Karam  1 , Mohammad Daher  1 , Christopher P Ames  4 , Shay Bess  5 , Alan H Daniels  3 , Munish C Gupta  6 , Richard Hostin  7 , Han Jo Kim  8 , Eric O Klineberg  9 , Lawrence G Lenke  10 , Pierce D Nunley  11 , Peter G Passias  12 , Frank J Schwab  13 , Christopher I Shaffrey  14 , Justin S Smith  15 , Renaud Lafage  13 , Virginie Lafage  13 ; International Spine Study Group  16
Affiliations

A New Normative Zone for Acetabular Anteversion Positioning in ASD Patients

Marc Boutros et al. J Orthop Res. 2026 Mar.

Abstract

Adult spinal deformity patients undergoing total hip arthroplasty experience higher hip dislocation rates than those with normal spinal alignment. The traditional Lewinnek safe zone does not account for spinopelvic variation such as pelvic retroversion. To address this, three patient-specific normative zones for acetabular anteversion were defined. A multicenter retrospective analysis of 146 adult spinal deformity patients and 47 asymptomatic controls was performed using three-dimensional biplanar radiograph reconstructions to measure spinopelvic alignment and acetabular orientation. Normative Zone 1, for patients not undergoing spinal realignment, was delineated by the 95% confidence interval limits: minimum anteversion = 0.3182 × pelvic tilt +2.947 and maximum anteversion = 0.3317 × pelvic tilt +25.823. Normative Zone 2, for patients following spinal realignment, was based on pelvic incidence: minimum anteversion = 0.0682 × pelvic incidence +9.7749 and maximum anteversion = 0.0698 × pelvic incidence +21.5218. Normative Zone 3, intended for cases with uncertain spinal correction plans, was defined as the intersection of Zones 1 and 2, yielding a narrower target anteversion range. These zones enable patient-specific cup placement that accounts for existing or planned spinal alignment, with the potential to reduce dislocation risk. Clinical Significance: This study provides acetabular cup orientation tailored to each patient's spinopelvic alignment and surgical plan, potentially reducing dislocation rates in spinal malalignment patients.

Keywords: Lewinnek zone; acetabular anteversion; adult spinal deformity; dislocation; total hip arthroplasty.

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References

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