What is Lordosis
Lordosis is the normal inward (concave) curvature of the spine in the cervical and lumbar regions, with lumbar lordosis being the most clinically significant and typically measuring approximately 49° in the standing position. 1, 2
Anatomical Definition and Normal Values
- Lumbar lordosis is the anterior convex curvature of the lumbar spine that is unique to humans and essential for upright posture 3
- Normal lumbar lordosis (L1-S1) averages 49° when standing and decreases to approximately 34° when sitting, representing nearly a 50% reduction 2
- The lordotic angle varies significantly based on individual factors including age, gender, body mass index, ethnicity, and activity level, making it difficult to establish universal "normal" values 1
- Cervical lordosis refers to the similar inward curve in the neck region, though lumbar lordosis is more commonly discussed in clinical contexts 4
Clinical Significance and Biomechanics
- Lumbar lordosis is dictated by pelvic incidence, spinal musculature, vertebral wedging, and disc health, with these factors being interdependent 3
- The degree of lordosis directly affects load distribution in the spine: compressive forces tend to decrease with increasing lordosis, while facet joint forces increase 5
- Loss of lordosis correlates with increased intradiscal pressure, which may explain why sitting (with reduced lordosis) increases disc stress 2
- Preservation of physiologic lumbar lordosis is critical when performing spinal fusion procedures, as loss of lordosis can lead to "flat-back syndrome" characterized by inability to stand erect and upper back pain 6
Pathological Variations
Loss of Lordosis (Hypolordosis)
- Loss of lumbar lordosis on static radiographs may simply reflect patient positioning, pain-related guarding, or muscle spasm rather than true structural pathology 7, 8
- Post-trauma muscle spasm commonly alters spinal alignment, with loss of cervical lordosis frequently seen after whiplash-type injuries 8
- Symptomatic loss of lumbar lordosis is a disabling complication of scoliosis surgery, most commonly caused by distraction instrumentation extending into the lower lumbar spine 6
Excessive Lordosis (Hyperlordosis)
- Lumbar hyperlordosis refers to exaggerated inward curvature and can occur in conditions such as achondroplasia, where patients typically exhibit lumbar hyperlordosis along with other spinal deformities 4
- Excessive hip extension creating hyperlordosis in the supine position may increase the risk of femoral nerve neuropathy during prolonged anesthetic procedures 9
- Exaggerated lumbosacral lordosis can be a presenting feature of spinal cord tethering, typically accompanied by pain, sensorimotor disturbances, and bladder/bowel dysfunction 7, 8
Clinical Assessment Considerations
- The optimal position for radiologic measurement of lordosis is standing with arms supported while shoulders are flexed at a 30° angle 1
- Sagittal plane balance is more important than absolute lordosis values; on full-length standing lateral radiographs with knees extended, the C7-S1 measurement should fall within 2 cm of the anterior aspect of the sacrum 6
- MRI is the preferred imaging modality when nerve root compression, spinal cord pathology, or intraspinal abnormalities are suspected, regardless of lordosis appearance on plain films 7
Common Clinical Pitfalls
- Do not assume lordosis changes on radiographs represent structural pathology without clinical correlation, as positioning and muscle guarding are common confounders 7, 8
- Muscle spasm presence does not correlate with structural instability; it represents a protective response rather than indicating ligamentous injury or need for surgical intervention 8
- In pediatric patients, do not delay evaluation for underlying metabolic (such as X-linked hypophosphatemia) or neuromuscular conditions when progressive or severe lordosis is present 7