ICD-10-CM · Spine

M43.05

Spondylolysis localized to the thoracolumbar junction, representing a defect or stress fracture of the pars interarticularis at the T12-L1 level.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 17
Region: Spine

Drawn from CDCICD10DataAAPCBostonscientificCMS

Documentation tips

What should appear in the chart to support M43.05.

Source · Editorial brief grounded in 5 cited references ↓

The provider must explicitly name the spinal region as 'thoracolumbar' or identify the T12-L1 junction — generic terms like 'lower thoracic' or 'upper lumbar' are insufficient for M43.05.
Imaging reports should reference pars interarticularis defect, stress reaction, or stress fracture at T12-L1; document whether CT, MRI, or plain radiograph confirmed the finding.
Distinguish spondylolysis (pars defect without slip) from spondylolisthesis (vertebral displacement) — document the absence of forward slippage if only M43.05 applies.
If conservative care (bracing, PT, activity restriction) has been tried, document duration and response; this supports medical necessity for advanced imaging or surgical consultation.
For athletes, note the sport, training load, and onset pattern (acute vs. chronic/insidious) to support clinical context and authorization requirements.

Related CPT procedures

Procedure codes commonly billed with M43.05. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

72020 $23.71

Single-view radiologic examination of the spine at a specified level.

72040 $39.75

Radiologic examination of the cervical spine capturing two or three views (e.g., AP, lateral, oblique).

72052 $62.79

Radiologic examination of the cervical spine using six or more distinct views, the highest-level plain-film cervical series in the CPT spine imaging family.

72100 $40.42

Radiologic examination of the lumbosacral spine capturing two or three views, used to evaluate the lumbar vertebrae and sacrum for injury, degeneration, or structural abnormality.

72110 $53.44

Radiologic examination of the lumbar spine (lumbosacral) with a minimum of four views, including oblique and/or bending views.

72114 $61.79

Radiologic examination of the lumbosacral spine, complete series with bending (flexion/extension) views — minimum of 6 views total.

72120 $42.09

Radiologic examination of the lumbosacral spine using bending views only, minimum of four views, to assess spinal flexibility and alignment.

72148 $191.72

Non-contrast MRI of the lumbar spine used to evaluate disc pathology, spinal stenosis, nerve root compression, and other structural abnormalities without administration of contrast material.

22612 $1,467.64

Posterior or posterolateral lumbar arthrodesis of a single interspace, performed via a posterior approach with bone graft and typically pedicle screw fixation to achieve vertebral segment fusion.

22630 $1,510.72

Posterior interbody arthrodesis of a single lumbar interspace, including laminectomy and/or discectomy performed to prepare the interspace for fusion rather than for decompression.

22800 $1,312.99

Posterior spinal arthrodesis for deformity correction spanning up to 6 vertebral segments, with or without application of a body cast.

63005 $1,192.41

Laminectomy at one or two lumbar vertebral segments for exploration or decompression of the spinal cord or cauda equina, performed without facetectomy, foraminotomy, or discectomy — excluding spondylolisthesis cases.

97110 $29.06

Therapeutic exercise billed per 15-minute unit, targeting strength, endurance, range of motion, or flexibility with direct one-on-one patient contact.

72156 View procedure details

72157 View procedure details

97012 View procedure details

97530 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M43.05 and adjacent codes.

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

Coding M43.05 when spondylolisthesis is also present at the same level violates the Excludes1 note under M43.0 — if slippage is documented, switch to M43.15.
Using M43.05 for a congenital pars defect is incorrect; congenital spondylolysis codes to Q76.2 per the Excludes1 note.
Defaulting to M43.00 (site unspecified) when the imaging report names T12-L1 — specificity is available and required; unspecified codes invite audit scrutiny.
Confusing the thoracolumbar region (T12-L1) with the lumbar region (L1-L5) and selecting M43.06 instead of M43.05 when the provider documents the thoracolumbar junction.
Assigning M43.05 alongside M43.15 for the same level — the two codes are mutually exclusive by Excludes1 rule; only one condition can exist at the same site.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M43.05 applies when imaging or clinical documentation confirms spondylolysis — a structural defect of the pars interarticularis — specifically at the thoracolumbar junction (T12-L1). This region sits at the biomechanical transition between the relatively rigid thoracic spine and the more mobile lumbar spine, making it a site of concentrated stress, particularly in athletes and laborers with repetitive hyperextension demands.

Do not use M43.05 when spondylolisthesis is present. If the pars defect has allowed forward vertebral slippage, the correct parent category shifts to M43.1 (Spondylolisthesis); M43.15 covers spondylolisthesis at the thoracolumbar region. The ICD-10-CM Excludes1 note under M43.0 explicitly bars coding spondylolysis and spondylolisthesis together — they are mutually exclusive at the same level. Similarly, congenital spondylolysis codes to Q76.2, not M43.05.

If spondylolysis is documented at multiple spinal levels including the thoracolumbar region, consider M43.09 (multiple sites). If the defect is isolated to the thoracic region above T12-L1, use M43.04; if it is lumbar (L1-L5), use M43.06. Accurate region documentation by the treating provider drives the entire code selection — imaging report language alone ("lower thoracic/upper lumbar") should prompt clarification before coding.

Sibling codes

Other billable codes under M43.0 (laterality / anatomic variants).

M43.04

Spondylolysis, thoracic region

M43.01

Spondylolysis, occipito-atlanto-axial region

M43.02

Spondylolysis, cervical region

M43.06

Spondylolysis, lumbar region

M43.09

Spondylolysis, multiple sites in spine

M43.00

Spondylolysis, site unspecified

M43.08

Spondylolysis, sacral and sacrococcygeal region

M43.03

Spondylolysis, cervicothoracic region

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What is the thoracolumbar region in ICD-10-CM spine coding?

The thoracolumbar region refers to the T12-L1 junction. In ICD-10-CM spinal codes, '05' as the 5th character consistently designates this transitional zone, distinct from thoracic (04) or lumbar (06) regions.

02Can I use M43.05 and M43.15 together for the same patient?

No. M43.0 (Spondylolysis) carries an Excludes1 note for spondylolisthesis (M43.1), meaning the two conditions cannot be coded together at the same spinal level. If slippage is confirmed, use M43.15 instead of M43.05.

03What if the imaging report says 'lower thoracic/upper lumbar' without specifying T12-L1?

Query the treating provider for clarification before assigning M43.05. Ambiguous regional language does not support a specific code; defaulting to M43.00 (unspecified) is safer than an unsupported specific assignment.

04A patient has spondylolysis at both the thoracolumbar and lumbar levels — which code applies?

Use M43.09 (Spondylolysis, multiple sites in spine) when defects are documented at more than one spinal region. Do not stack individual site codes for the same condition category.

05Is M43.05 appropriate for a pars defect present since childhood now causing adult pain?

Yes, if the provider documents it as acquired or not further specified as congenital. If the record establishes a congenital origin, code Q76.2 instead. The Excludes1 note under M43.0 directs congenital spondylolysis to Q76.2.

06Does M43.05 require a 7th character?

No. M43.05 is a completed billable code with no 7th-character extension required. Seventh-character extensions for encounter type (A/D/S) apply to trauma injury codes in the S-chapter, not to M-chapter dorsopathy codes.

07What CPT procedures are commonly linked to M43.05?

Diagnostic imaging (spine X-ray series, MRI lumbar/thoracic), physical therapy codes, and spinal fusion procedures (e.g., 22612, 22630) are frequently paired when M43.05 is the primary diagnosis driving treatment.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026, code M43.05
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M40-M43/M43-/M43.05
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M43.05
04
bostonscientific.com
https://www.bostonscientific.com/content/dam/bostonscientific/Reimbursement/pain-management/pdf/ICD-10-CM-Diagnosis-Coding-Guide-for-SCS.pdf
05CMS ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

Mira AI Scribe

Mira AI Scribe captures the spinal region by name (thoracolumbar junction, T12-L1), the imaging modality and finding (pars interarticularis defect, CT or MRI confirmation), and explicit notation of no vertebral slippage — preventing a downcode to M43.00 (unspecified site) or a miscoded upgrade to M43.15 (spondylolisthesis, thoracolumbar) that would trigger an Excludes1 conflict on audit.

See how Mira captures M43.05 documentation