Acquired exaggeration of the lumbar inward curve (hyperlordosis) attributable to posture rather than a structural vertebral abnormality or congenital cause.

Documentation tips

What should appear in the chart to support M40.46.

Source · Editorial brief grounded in 6 cited references ↓

• Specify the region as 'lumbar' by name — vague terms like 'low back hyperlordosis' without regional designation push the claim to M40.40 (unspecified), a weaker specificity level.
• Record whether the lordosis is postural (reducible with positioning) versus structural; only postural presentations belong under M40.4x.
• Include contributing postural or biomechanical findings: hip flexor tightness, anterior pelvic tilt, weak core musculature — these support medical necessity for physical therapy and conservative management.
• When lumbar spine X-rays are ordered, ensure the radiology report captures lumbar lordosis angle or Cobb measurement so imaging codes (e.g., 72100, 72110) are defensible.
• If an underlying neuromuscular or systemic disease drives the hyperlordosis, sequence the primary condition first and list M40.46 as an additional diagnosis per the 'Code first underlying disease' instruction at the M40 category level.
• Distinguish lumbar from lumbosacral involvement: if the curve extends to the L5-S1 junction by report or imaging, M40.47 is the correct code, not M40.46.

Related CPT procedures

Procedure codes commonly billed with M40.46. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M40.46 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Billing M40.4 (non-billable parent) instead of drilling down to M40.46 — payers will reject the claim for insufficient specificity.
• Using M40.46 when the patient's chart indicates congenital lordosis or a postprocedural deformity — both are Excludes1 at the M40 category and require Q76.4 or M96.- respectively.
• Confusing postural lordosis (M40.46) with unspecified lordosis (M40.56) — only use M40.56 when the documentation does not support a postural etiology.
• Coding M40.46 when the curve involves the lumbosacral region, where M40.47 is the site-specific correct code.
• Omitting the 'Code first' sequencing instruction when a documented underlying disease is the root cause of the acquired lordosis, which inverts the coding order and may trigger an audit flag.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Sibling codes

Other billable codes under M40.4 (laterality / anatomic variants).