Spine-related leg pain: Definitions, etiology, clinical presentation, and management

Spine-related leg pain (SRLP) is a common and clinically important presentation, affecting a substantial proportion of individuals with lumbar spine disorders. Compared to those with isolated axial low back pain, these patients experience higher pain intensity, greater disability, worse long-term outcomes, and increased healthcare utilization. Clinical management is complicated by inconsistent terminology among musculoskeletal healthcare providers, with the widespread and imprecise use of the term sciatica contributing to diagnostic uncertainty and treatment variability across heterogeneous conditions. The International Association for the Study of Pain (IASP) distinguishes three categories of SRLP: radiculopathy, radicular pain, and somatic referred pain, each differing in underlying mechanisms, clinical presentation, prognosis, and management considerations. Lumbar radiculopathy is characterized by nerve root loss of function and corresponding neurologic deficits; radicular pain involves irritation of the nerve root with neural gain of function; and somatic referred pain results from nociceptive input from spinal structures that produce distal pain without direct nerve root dysfunction. This commentary operationalizes the updated IASP framework for physical therapists by synthesizing contemporary mechanistic concepts into a pragmatic, clinically oriented resource to support structured, mechanism-based clinical reasoning. Emphasis is placed on differentiating SRLP phenotypes during examination, setting appropriate expectations, guiding conservative management, and identifying when escalation, interdisciplinary collaboration, or referral is warranted. By adopting standardized terminology and applying a structured yet adaptable reasoning framework, physical therapists may enhance diagnostic precision, improve individualized decision-making, and more effectively guide patients with SRLP toward meaningful recovery.