Radiographic Categorization of the Hip-spine Syndrome in the Setting of Hip Osteoarthritis and Sagittal Spinal Malalignment.

BACKGROUND: Interplay between degenerative hip and spine conditions (Hip-Spine Syndrome [HiSS]) warrants effective communication between respective surgeons. We identified radiographic parameters to distinguish a subset of patients with HiSS by evaluating hip osteoarthritis (HOA) in patients with and without spinopelvic malalignment, categorizing patients into respective HiSS types, and comparing radiographic parameters. METHODS: All patients with full-body orthogonal radiography from 2013 to 2016 were reviewed (n = 1,389). Using sagittal/coronal hip radiographs, HOA (Kellgren-Lawrence Grade) was noted, and pelvic incidence-lumbar lordosis mismatch (PI-LL) > 10° was considered spinal malalignment. Patients groups included non-HiSS (PI-LL ≤ 10°/Grade 0/n = 444), Hip (PI-LL ≤ 10°/Grade 3-4/n = 78), Spine (PI-LL > 10°/Grade 0/n = 297), or Hip-Spine (PI-LL > 10°/Grade 3-4/n = 30). Parameters were compared using ANOVA with post-hoc Bonferroni analysis. RESULTS: HiSS Hip type patients had less hip extension capability compared with non-HiSS, Spine, and Hip-Spine type patients, reflected by lowest pelvic tilt (PT)/sagittal retroversion (11.3° versus 16.5°/29.2°/25.2°, respectively) and less hip extension per sacrofemoral angle (10.1° versus 19.5°/28.4°/23.1°, respectively) (P < 0.001), as well as 4.7° increase in anterior tilt/sagittal anteversion compared with age-matched individuals. Hip-Spine type patients had less pelvic retroversion than Spine type patients (P = 0.045); these differences were greater when referenced to age-matched individuals (P < 0.001). Hip-Spine type patients had less hip extension than Spine type patients (P = 0.013). Hip type patients had greater knee flexion than non-HiSS type patients (6.4° versus 2.6°; P < 0.001). Moreover, Hip-Spine type patients had comparable lower extremity alignment compared with Spine type patients, except for greater posterior pelvic shift. CONCLUSION: Our novel HiSS categorization used established classification methods and supported PT use to potentially improve the ability to discern HiSS types/pathologies in a subset of patients with HOA and spinal sagittal malalignment. HOA grade 3 to 4 with PT <15° are categorized as Hip type and those with PT >25° are Hip-Spine type with sagittal malalignment, which may impact acetabular arthroplasty component placement.

Duke Scholars

Author Peter Passias Orthopaedic Surgery