Lordosis

01Pathophysiology

The lumbar spine normally maintains an inward (lordotic) curvature that serves as a biomechanical counterbalance to the thoracic kyphosis above it. This curvature distributes axial loading forces along the spine and positions the head over the pelvis for upright posture. Lordosis becomes pathological when this curve is exaggerated beyond the normal range (generally considered $>60\mathrm{°}>60°$ by Cobb angle measurement on lateral radiograph).

The core mechanism in most cases is anterior pelvic tilt. When the pelvis tilts forward, the lumbar spine must compensate by increasing its lordotic curve to keep the trunk upright. This is why conditions that pull the pelvis forward (tight hip flexors, hip flexion contractures, bilateral hip dislocations) or shift the center of gravity anteriorly (obesity, pregnancy, large abdominal masses) are strongly associated with hyperlordosis.

In neuromuscular disease, the mechanism is different. Weakness of the trunk extensors and abdominal muscles means the spine cannot be held in a neutral position against gravity. The lumbar spine "falls" into increased lordosis because there is no muscular counterforce. This is why Duchenne muscular dystrophy classically presents with progressive hyperlordosis alongside the Gowers sign and pseudohypertrophy of the calves.

In spondylolisthesis, the anterior slippage of one vertebral body over another disrupts the normal alignment, and the segments above must increase their lordotic angle to compensate, resulting in a segmental or regional hyperlordosis.

The pain experienced by patients is the direct consequence of this altered biomechanics. The exaggerated curve compresses the posterior elements of the vertebrae (facet joints, laminae, spinous processes), causing facet joint arthropathy and stenosis of the central canal or neural foramina. This explains why patients with severe lordosis may develop neurogenic claudication (pain and weakness in the legs worsened by standing and walking, relieved by sitting or bending forward) and radiculopathy.

02Classification and Clinical Manifestation

By Severity

03Diagnostic Workup

The evaluation begins with clinical examination. On lateral inspection, the examiner observes whether the lumbar curve is exaggerated. The Thomas test is performed to identify hip flexor contracture, which is one of the most common correctable causes: the patient lies supine and flexes one hip fully to flatten the lumbar spine against the table. If the contralateral thigh lifts off the table (the hip cannot fully extend), the test is positive, indicating a tight iliopsoas. The forward bending test is the critical maneuver for distinguishing flexible from structural lordosis. If the exaggerated curve flattens when the patient bends forward, the lordosis is postural. If it persists, it is structural and warrants imaging.

The best initial imaging study is a lateral standing radiograph of the lumbar spine. The Cobb angle is measured between the superior endplate of L1 and the superior endplate of S1. Normal lumbar lordosis ranges from approximately $40\mathrm{°}40°$ to $60\mathrm{°}60°$. Values above this range confirm hyperlordosis. This film also allows detection of spondylolisthesis (anterior vertebral body slippage), which is a commonly tested underlying cause.

For patients with neurological symptoms (lower extremity weakness, numbness, radiculopathy, or bowel/bladder dysfunction), MRI is the most accurate test. It provides direct visualization of the spinal cord, cauda equina, nerve roots, and surrounding soft tissues, and identifies foraminal stenosis or disc herniation caused by the abnormal curvature.

Full-length standing radiographs with sagittal balance parameters (pelvic incidence, sacral slope, pelvic tilt, C7 sagittal vertical axis) are used in surgical planning but are less commonly tested on licensing examinations.

04Management and Treatment

Conservative management is the first-line approach for the majority of patients, particularly those with postural lordosis. The goal is to reduce anterior pelvic tilt and restore muscular balance around the lumbar spine. This involves:

• Hip flexor stretching: Sustained iliopsoas and rectus femoris stretches to reduce the anterior pull on the pelvis. Sessions should be performed daily, holding each stretch for at least 30 seconds.

• Core strengthening: Exercises targeting the abdominal muscles (transversus abdominis, internal obliques) and gluteal muscles. Strengthening these groups provides a posterior counterforce that reduces lumbar lordosis. Planks and pelvic tilts are commonly prescribed.

• Weight loss: In patients with truncal obesity, reducing the anterior load on the spine directly decreases the compensatory lordotic curve.

• Posture re-education: Ergonomic adjustments for workstation setup and avoidance of prolonged standing in hyperlordotic posture.

Bracing with a TLSO is indicated in skeletally immature patients (Risser sign 0 to 3) with moderate curves that are progressing. The brace works by providing an external corrective force, analogous to its use in adolescent idiopathic scoliosis. Bracing is not effective in skeletally mature adults with structural lordosis.

Surgical intervention is reserved for patients who meet at least one of the following criteria: curve progression despite conservative treatment, severe deformity causing sagittal imbalance, or neurological compromise (radiculopathy, cauda equina syndrome). The standard procedure is posterior spinal instrumentation and fusion using pedicle screws and rods. In cases where the curve is rigid and cannot be corrected by posterior instrumentation alone, an anterior release (discectomy at multiple levels) is performed first to mobilize the spine before posterior fixation.

Contraindications and cautions: In patients with neuromuscular disease, aggressive surgical correction must be balanced against the risk of respiratory compromise (already present in conditions like Duchenne muscular dystrophy). These patients require thorough preoperative pulmonary function testing. NSAIDs should be used with caution in patients with renal impairment or peptic ulcer disease.

The "Next Best Step" logic for a vignette presenting with hyperlordosis and low back pain in an otherwise healthy patient with a positive Thomas test is: physical therapy focused on hip flexor stretching and core strengthening. Surgery is almost never the answer on exam questions unless the vignette describes neurological deficits or failed conservative management.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common error students make on lordosis questions is confusing the direction of curvature with kyphosis. Remember: lordosis is the curve that goes inward (concave posteriorly), while kyphosis curves outward (convex posteriorly). An "exaggerated lumbar curve" always points toward lordosis, not kyphosis. If the vignette says "loss of normal lumbar lordosis," think of ankylosing spondylitis or muscle spasm, not hyperlordosis.

A second trap involves the Thomas test. Students may recognize it as a hip examination maneuver but fail to connect it to the spine. The Thomas test is not just testing the hip; it is testing the cause of the lordosis. A positive Thomas test in a patient with hyperlordosis tells you the etiology is hip flexor tightness, and the management is stretching and physical therapy, not imaging or surgery.

The third common pitfall is jumping to surgery. Vignettes about lordosis almost always test whether you will choose conservative management first. Unless the stem contains red flags (bowel/bladder dysfunction, progressive motor weakness, or failure of prolonged conservative therapy), the answer is physical therapy and postural correction.

Finally, be alert for lordosis appearing as a secondary finding in a vignette about another disease. A child with Duchenne muscular dystrophy who has progressive hyperlordosis, or a pregnant patient with worsening low back pain and exaggerated lumbar curve: the lordosis in these cases is not the primary diagnosis. The question is testing whether you recognize the underlying condition and understand that the lordosis is compensatory.

The core competency being tested is the ability to differentiate flexible from structural deformity, identify the underlying cause through directed physical examination, and apply the principle that conservative management precedes surgical intervention in the absence of neurological emergency.