ICD-10-CM · Hip

M16.12

Primary osteoarthritis of the left hip only, with no traumatic, dysplastic, or secondary cause identified — the degenerative process is idiopathic and confined to a single joint.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 14
Region: Hip

Drawn from CDCICD10DataCMSAAOSAAPC

Documentation tips

What should appear in the chart to support M16.12.

Source · Editorial brief grounded in 6 cited references ↓

Explicitly name the affected side as 'left' in the assessment — do not rely on laterality buried in imaging reports alone.
Record radiographic findings that support primary OA: joint space narrowing, osteophyte formation, subchondral sclerosis, and Kellgren-Lawrence grade if graded.
State 'primary' or 'idiopathic' osteoarthritis to distinguish from post-traumatic or dysplasia-related OA; absence of a documented prior injury or developmental disorder is not sufficient on its own.
Document functional impact (e.g., reduced walking tolerance, pain with weight-bearing) to support medical necessity for injections, PT, or surgery.
For surgical authorization, note the duration of conservative care attempted (e.g., NSAIDs, PT, corticosteroid injections) and the patient's response.

Related CPT procedures

Procedure codes commonly billed with M16.12. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

27130 $1,162.02

Primary total hip arthroplasty replacing both the acetabular socket and proximal femoral components with prosthetic implants, with or without bone graft.

27132 $1,504.04

Conversion of a previously operated hip — any prior surgery except total hip arthroplasty — to a complete total hip arthroplasty, replacing both femoral and acetabular components, with or without bone graft.

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

20611 $104.21

Aspiration or injection of a major joint or bursa performed under real-time ultrasound guidance, with permanent image documentation.

29862 $759.87

Arthroscopic hip surgery involving chondroplasty, abrasion arthroplasty, and/or partial labral resection to address damaged cartilage or labral pathology.

29863 $757.20

Arthroscopic surgical procedure on the hip joint involving removal of inflamed synovial membrane tissue.

73501 $33.73

Single-view X-ray of one hip, including the pelvis when clinically indicated — the minimum imaging study in the hip radiograph family.

73502 $48.77

Radiologic exam of a single hip, capturing two or three views, including the pelvis when performed.

73503 $62.79

Radiologic examination of a single hip, including the pelvis when performed, capturing a minimum of four views from different angles.

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.

97140 $27.72

Skilled, hands-on manual therapy techniques — including joint mobilization/manipulation, manual lymphatic drainage, and manual traction — applied to one or more body regions, billed per 15-minute unit.

99213 $95.19

Established patient office or outpatient visit requiring 20–29 minutes of total time or low-complexity medical decision-making.

99214 $135.61

Office visit for an established patient requiring moderate-complexity medical decision making (MDM), or 30–39 minutes of total provider time on the date of service.

99215 $192.39

Highest-level office or outpatient E/M visit for an established patient, qualifying via high-complexity medical decision making or 40–54 minutes of total provider time on the date of service.

Common coding pitfalls

The recurring mistakes coders make with M16.12 and adjacent codes.

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

Coding M16.11 (right hip) when the note clearly documents left-sided symptoms — always verify laterality against the physical exam and imaging, not just the procedure order.
Using M16.12 when the chart documents a prior hip trauma or dysplasia; those cases require M16.52 (post-traumatic, left) or M16.32 (dysplasia-related, left) instead.
Stacking M16.11 and M16.12 when both hips are affected — bilateral primary hip OA codes to M16.0, a single billable code.
Defaulting to the non-billable parent M16.1 or the unspecified M16.10 when laterality is clearly documented as left in the note.
Appending a symptom code for left hip pain (M25.552) alongside M16.12 — once the definitive diagnosis is established, the symptom code is redundant per ICD-10-CM guidelines.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M16.12 is the correct code when the provider documents primary (idiopathic) osteoarthritis limited to the left hip. 'Primary' means the degeneration has no identifiable underlying cause — not post-traumatic, not dysplasia-related, not secondary to another systemic disease. If a prior hip injury, developmental dysplasia, or secondary cause is documented, move to the appropriate M16.3x, M16.5x, or M16.7 code instead.

Use M16.12 in place of the non-billable parent M16.1 whenever the laterality is confirmed as left. If the right hip is also affected, switch to M16.0 (bilateral primary OA of hip) — do not stack M16.11 and M16.12. If laterality is genuinely undocumented at the time of coding, M16.10 (unspecified hip) is available, but the AAOS resident guide flags unspecified hip codes as codes that should never be used when the side is known.

M16.12 groups to MS-DRG 553/554 (Bone Diseases and Arthropathies with/without MCC) under MS-DRG v43.0. It pairs with a wide range of orthopedic procedures, from joint injections (20610, 20611) through total hip arthroplasty (27130), and physical therapy evaluation codes. Confirm payer LCD/NCD requirements for surgical procedures; some payers require documented failure of conservative care before authorizing arthroplasty.

Sibling codes

Other billable codes under M16.1 (laterality / anatomic variants).

M16.11

Unilateral primary osteoarthritis, right hip

M16.10

Unilateral primary osteoarthritis, unspecified hip

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When should I use M16.12 versus M16.0?

Use M16.12 when only the left hip has primary OA. Use M16.0 when the provider documents primary OA in both hips. Never report M16.11 and M16.12 together for bilateral disease — M16.0 is the correct single code.

02Can I use M16.12 if the patient had a prior hip fracture or surgery on the left side?

No. A prior trauma history points to post-traumatic OA; use M16.52 (unilateral post-traumatic osteoarthritis, left hip) instead. 'Primary' means idiopathic — no identifiable structural or traumatic cause.

03Does M16.12 require imaging to be coded?

ICD-10-CM does not mandate imaging as a coding prerequisite, but clinical validation for primary hip OA typically requires radiographic evidence of joint space narrowing or degenerative changes. Most payers and audit tools expect imaging documentation to support the diagnosis and any associated procedure.

04Is M16.10 ever appropriate when the patient is clearly left-sided?

No. M16.10 (unspecified hip) is reserved for cases where laterality is genuinely undocumented. If the note documents left hip OA, M16.12 is required. The AAOS resident coding guide explicitly flags unspecified hip codes as codes to avoid when the side is known.

05What MS-DRGs does M16.12 map to?

M16.12 groups to MS-DRG 553 (Bone Diseases and Arthropathies with MCC) and MS-DRG 554 (Bone Diseases and Arthropathies without MCC) under MS-DRG v43.0, per the ICD-10-CM tabular data.

06Should I also report a hip pain code (M25.552) alongside M16.12?

No. Once a definitive diagnosis of primary OA is established, symptom codes such as M25.552 (pain in left hip) are not reported separately per ICD-10-CM coding guidelines — the OA code captures the clinical picture.

07What CPT codes commonly pair with M16.12 for a total hip arthroplasty claim?

27130 (total hip arthroplasty) is the primary surgical code. 27132 applies when converting a prior hip procedure to THA. Confirm payer prior-authorization requirements and document failed conservative care before submitting surgical claims with M16.12.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (effective October 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M15-M19/M16-/M16.12
03
cms.gov
https://www.cms.gov/medicare/coding/icd10/downloads/icd10clinicalconceptsorthopedics1.pdf
04
aaos.org
https://www.aaos.org/globalassets/quality-and-practice-resources/coding-and-reimbursement/resident-guide/resident-guide_icd10.pdf
05
aapc.com
https://www.aapc.com/codes/icd-10-codes/M16.12
06
icdcodes.ai
https://icdcodes.ai/diagnosis/left-hip-osteoarthritis/documentation

Mira AI Scribe

The Mira AI Scribe captures laterality ('left hip'), diagnosis type ('primary' or 'idiopathic'), radiographic findings (joint space narrowing, osteophytes, KL grade), functional limitation, and prior conservative treatment from the encounter note — ensuring M16.12 is assigned rather than an unspecified or incorrect-side code, and preventing audit flags for missing specificity or unsupported medical necessity on surgical or injection claims.

See how Mira captures M16.12 documentation