ICD-10-CM · Hip

M16.51

Degenerative joint disease of the right hip that developed as a direct consequence of a prior traumatic injury to that joint, coded as a unilateral condition with confirmed right-side laterality.

Verified May 8, 2026 · 7 sources ↓

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

Drawn from CDCICD10DataAAPCCMSAAHKS

Documentation tips

What should appear in the chart to support M16.51.

Source · Editorial brief grounded in 7 cited references ↓

Explicitly document the causal relationship between the prior trauma and the current hip OA — 'osteoarthritis of the right hip resulting from a 2018 acetabular fracture' satisfies the requirement; 'history of hip fracture' alone does not.
Record laterality by name (right hip) in the assessment or diagnosis line, not only in the history section, so coders can assign M16.51 without inferring from context.
Include imaging findings that support arthritic change — Tönnis grade, joint-space narrowing on weight-bearing AP pelvis, osteophyte formation, or subchondral sclerosis — to substantiate medical necessity for surgical or conservative interventions.
Note any prior surgical treatment of the original trauma (ORIF, hip dislocation reduction) to reinforce the post-traumatic pathway and distinguish from primary or dysplastic OA.
Document conservative care attempted before arthroplasty (PT, NSAIDs, intra-articular injections) so the clinical record supports the trajectory from post-traumatic diagnosis to surgical necessity.

Related CPT procedures

Procedure codes commonly billed with M16.51. 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.

27134 $1,695.43

Revision of total hip arthroplasty involving replacement of both the femoral and acetabular components in a single operative session.

27137 $1,317.67

Revision of a total hip arthroplasty involving the acetabular component only, with or without autograft or allograft

27138 $1,367.10

Revision of total hip arthroplasty involving removal and replacement of the femoral component only, with or without bone graft.

27236 $1,089.87

Open treatment of a proximal femoral fracture at the femoral neck, using internal fixation hardware or prosthetic replacement to stabilize the fracture site.

27250 $174.69

Closed manual reduction of a traumatic hip dislocation performed without anesthesia — the femoral head is physically manipulated back into the acetabulum using skilled technique alone.

27252 $718.45

Closed reduction of a traumatic hip dislocation performed under anesthesia, manipulating the femoral head back into the acetabulum without surgical incision.

73502 $48.77

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

73521 $41.75

Bilateral hip X-ray examination capturing two radiographic views of both hips, including the pelvis when performed.

73523 $61.46

Radiologic examination of both hips, including the pelvis when performed, requiring a minimum of five views captured from multiple projections.

27096 $175.69

Injection into the sacroiliac joint with fluoroscopic or CT image guidance, including arthrography when performed.

20610 $68.81

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

Common coding pitfalls

The recurring mistakes coders make with M16.51 and adjacent codes.

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

Assigning M16.11 (unilateral primary OA, right hip) when the record documents a traumatic cause — primary and post-traumatic OA are mutually exclusive categories; the etiology drives the code selection.
Using the non-billable parent M16.5 instead of drilling to M16.51 — M16.5 is non-specific and will not pass claim edits requiring a billable code.
Defaulting to M16.50 (unspecified hip) when the provider has clearly documented the right side — laterality is documented, so use it; unspecified codes invite ADR requests.
Coding M16.51 when both hips are affected post-traumatically — bilateral post-traumatic OA belongs at M16.4, not two units of M16.51.
Failing to link the historical injury to the current OA in the record, which exposes the claim to audit challenge if a payer queries the post-traumatic designation.

Clinical context

Source · Editorial summary grounded in 7 cited references ↓

M16.51 is the correct code when a provider documents osteoarthritis of the right hip that is causally linked to a previous trauma — such as a prior hip fracture, acetabular fracture, femoral head injury, hip dislocation, or significant soft-tissue injury that altered joint mechanics. The trauma-to-OA causal relationship must be explicitly stated in the medical record; do not infer it from incidental history alone.

Within the M16.5 family, the 6th character distinguishes laterality: M16.50 = unspecified hip, M16.51 = right hip, M16.52 = left hip. M16.51 requires documented right-side involvement. If both hips show post-traumatic OA, use M16.4 (bilateral post-traumatic osteoarthritis of hip) instead. If the osteoarthritis has no traumatic origin, pivot to M16.11 (unilateral primary, right) or M16.7 (other unilateral secondary, right) depending on etiology.

This code maps to MS-DRG 553 (Bone diseases and arthropathies with MCC) and 554 (without MCC) and appears on CMS's list of ICD-10-CM codes supporting medical necessity for home health physical therapy. It is frequently paired with surgical CPT codes for total or partial hip arthroplasty and with imaging codes when radiographic confirmation of joint-space narrowing or deformity is documented.

Sibling codes

Other billable codes under M16.5 (laterality / anatomic variants).

M16.50

Unilateral post-traumatic osteoarthritis, unspecified hip

M16.52

Unilateral post-traumatic osteoarthritis, left hip

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01What is the difference between M16.51 and M16.11?

M16.11 is unilateral primary OA of the right hip — idiopathic, age-related degeneration with no identified cause. M16.51 is unilateral post-traumatic OA of the right hip — degeneration directly caused by a prior injury. The provider must document the traumatic etiology to justify M16.51; without that linkage, M16.11 or M16.9 is the fallback.

02Can I code M16.51 if the original injury happened decades ago?

Yes. The ICD-10-CM classification does not impose a time limit between the original trauma and the resulting OA. What matters is that the provider establishes a causal relationship in the current documentation, regardless of how long ago the injury occurred.

03What code do I use if the patient has post-traumatic OA in both hips?

Use M16.4 (bilateral post-traumatic osteoarthritis of hip). Do not assign M16.51 and M16.52 together — the bilateral code captures both sides in one code when both are post-traumatic.

04Is M16.51 valid as a primary diagnosis for total hip arthroplasty?

Yes. M16.51 is a billable, specific code and is an accepted primary diagnosis to support CPT 27130 (total hip arthroplasty) and related arthroplasty procedures. Ensure the operative report and pre-op documentation reflect the right hip and the post-traumatic etiology.

05Does M16.51 require a 7th character?

No. M16.51 is an M-code (musculoskeletal, chronic condition) and does not use 7th-character extensions. The A/D/S encounter designations apply to injury S-codes, not to established degenerative diagnoses in Chapter 13.

06What imaging documentation best supports M16.51?

Weight-bearing AP pelvis or hip X-ray findings are standard — document joint-space narrowing, osteophytes, subchondral sclerosis, or cystic changes. Tönnis grading or Kellgren-Lawrence grading of the right hip, noted in the radiology report or provider assessment, strengthens the medical necessity record.

07If the provider only writes 'hip OA, history of fracture' without explicitly linking them, can I still use M16.51?

This is genuinely ambiguous. Per ICD-10-CM Official Guidelines, code assignment requires provider documentation of the causal relationship. A history notation alone is not sufficient — query the provider to confirm the post-traumatic etiology before assigning M16.51 over M16.11.

Sources & references

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

Mira AI Scribe

Mira captures the treating provider's explicit statement linking a prior right hip trauma to current arthritic degeneration, along with confirmed right-side laterality, imaging findings (joint-space narrowing, osteophytes, Tönnis grade), and the history of conservative treatment. That documentation locks in M16.51 over the unspecified M16.50 or the non-traumatic M16.11, preventing laterality downcoding and protecting the post-traumatic designation from payer audit.

See how Mira captures M16.51 documentation