Lumbar spondylolysis: integrating imaging, functional movement assessment, and biomechanics in a narrative review

Lumbar spondylolysis (LS) is a stress-related defect of the pars interarticularis. Structural imaging, functional movement assessment, and biomechanical investigation address different aspects of this disorder. This narrative review integrates these domains while distinguishing clinical evidence, experimental findings, and mechanistic inference. Computed tomography (CT) characterizes cortical morphology, whereas magnetic resonance imaging (MRI) detects marrow stress responses without ionizing radiation. MR bone imaging offers additional cortical information, but fracture detection and lesion staging require separate evaluation. Direct LS-specific movement evidence remains limited: the principal gait study included only five affected children with cerebral palsy, and athlete studies mainly concern hip mobility or trunk function. Finite element and cadaveric studies identify loading-dependent changes in pars stress and segmental motion; their numerical outputs are conditional on anatomy and experimental assumptions. We propose a morphology-mechanics-function framework with explicit source-to-relationship mapping, illustrative clinical scenarios, and prospective validation targets. Imaging supports lesion characterization, while movement assessment may complement functional evaluation. Biomechanical findings inform hypotheses about loading and stability but cannot establish treatment superiority. Whether integrating these measures improves prognosis or treatment selection beyond conventional assessment remains a research question.