Abstract
Introduction
Spinopelvic mobility has been associated with THA outcome. To-date spine assessments have been made quasi-statically, using radiographs, in standing and seated positions but dynamic spinopelvic mobility has not been well explored. This study aims to determine the association between dynamic (motion analysis) and quasi-static (radiographic) sagittal assessments and examine the association between axial and sagittal spinal kinematics in hip OA patients and controls.
Methods
This is a prospective, IRB approved, cohort study of 12 patients with hip OA pre-THA (6F/6M, 67±10 years) and six healthy controls (3F/3M, 46±18 years). All underwent lateral spinopelvic radiographs in standing and seated bend-and-reach (SBR) positions. Pelvic tilt (PT), pelvic-femoral-angle (PFA) and lumbar lordosis (LL) angles were measured in both positions and the differences (Δ) in angles between SBR and standing were computed. All participants performed two dynamic tasks at the motion laboratory: seated maximal trunk rotation (STR) and seated bend and reach (SBR). Three-dimensional joint motion data were collected and processed by a 10-camera infrared motion analysis system (Vicon, Nexus 2.10, UK). Total axial and sagittal spine (mid-thoracic to lumbar) range of motion (ROM) were calculated for STR and SBR, respectively.
Results
ΔLL for SBR and motion analysis spinal flexion for SBR moderately correlated (ρ=0.4, p=0.007). Dynamic spinal rotation and flexion significantly, strongly, correlated (ρ=0.6 p=0.007). OA patients compared to healthy participants showed significant less ΔPFA (53°±21° vs. 77°±14°; p<0.001); ΔPT (−17°±8° vs. 9°±15°; p<0.001), ΔLL (35°±15° vs. 43° ±9°; p<0.001), axial spinal rotation during STR (62° ±12°vs. 79° ±8°, p<.001) and less, but not significant, spine flexion during SBR (36° ±15° vs. 44° ±10°, P=.1).
Conclusion
Dynamic sagittal and axial spinal ROM showed moderately correlated. Motion analysis can provide valid assessments for spine mobility. OA patients compared to healthy participants showed significant less ΔPFA, ΔPT, ΔLL, axial spinal rotation during STR. Surgeons should be aware that patients with less spine mobility that could affect the stability of THA and increase the risk of poor outcomes.
