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. 2025 Oct 16:123:110013.
doi: 10.1016/j.gaitpost.2025.110013. Online ahead of print.

The contribution of lower limbs to Pelvic Tilt: A baseline and postoperative full-body analysis

Marc Khalifé  1 , Renaud Lafage  2 , Bassel Diebo  3 , Alan Daniels  3 , Munish Gupta  4 , Christopher Ames  5 , Shay Bess  6 , Douglas Burton  7 , Khaled Kebaish  8 , Michael Kelly  9 , Han Jo Kim  10 , Eric Klineberg  11 , Lawrence Lenke  12 , Stephen Lewis  13 , Peter Passias  14 , Christopher Shaffrey  15 , Justin S Smith  16 , Frank Schwab  2 , Virginie Lafage  2 ; ISSG
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Free article

The contribution of lower limbs to Pelvic Tilt: A baseline and postoperative full-body analysis

Marc Khalifé et al. Gait Posture. .
Free article

Abstract

Background: Pelvic tilt (PT) has been a parameter of interest in biomechanics of spinal deformity for decades. It remains unclear how patients achieve different values of PT pre- and postoperatively.

Research question: This study aimed at assessing the relative contribution of hip extension, knee flexion and ankle extension to PT, factoring malalignment and hip osteoarthritis (OA).

Methods: This retrospective study included Adult Spinal Deformity (ASD) patients with preoperative full-body radiographs from a multicenter database, with a sub-analysis of patients with complete 1-year follow-up (1yFU). Age and PI-adjusted normative PT (NormPT) and offset from norm (OffPT) were calculated, as for sacro-femoral angle (SFA), knee flexion angle (KA) and ankle angle (AA). Multivariate linear regression models controlling for age, frailty, severe hip OA, pelvic incidence (PI), SFA, and KA were used to predict PT at baseline, and offset from NormPT. Another model was generated to predict PT change.

Results: 600 patients at baseline and 336 with 1yFU were included. Mean age was 61 ± 15, 70.2 % were females and 40 % were revision cases. At baseline, regression analysis revealed that 0.9° increase in hip extension (SFA) and a 0.6° increase in knee flexion (KA) amounted to 1° increase in PT. Knee and ankle contribution to PT significantly increased for while hip extension decreased as TPA augmented (p < 0.001). Patients with low deformity compensated with hip extension, while knee flexion was the largest contributor of PT in high deformity patients: 70.7 % (44.7 - 111.9). Median contribution of knee flexion to PT was larger for patients who presented hip OA.

Significance: This study demonstrated that PT is a phenomenon driven by extension of the hips and flexion of the knees and proposed values to predict PT from those two compensatory mechanisms. Magnitude of spinal deformity and hip OA alters the magnitude of SFA/KA contribution to PT.

Keywords: Hip extension; Knee flexion; Lower limb; Pelvic retroversion; Pelvic tilt; Sagittal malalignment.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Multi center reports financial support was provided by International Spine Study Group. Marc KHALIFE reports financial support was provided by French Society for Orthopaedic and Traumatological Surgery. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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