Glossary · Clinical

Bursitis

Bursitis is inflammation of a bursa—a fluid-filled sac that cushions bones, tendons, and muscles near joints—most commonly caused by repetitive motion, acute trauma, infection, or underlying inflammatory disease. Accurate site, laterality, and etiology documentation is essential for selecting the correct ICD-10-CM code and supporting medical necessity for injection or surgical procedures.

Verified May 8, 2026 · 8 sources ↓

Drawn from CMSAAOSIcdcodesAAPCICD10Data

Definition

Source · Editorial summary grounded in 8 cited references ↓

A bursa is a small, synovium-lined sac strategically positioned at high-friction anatomical interfaces—between tendons and bone, skin and bone, or muscle layers. Under normal conditions it reduces mechanical stress. When the bursal wall becomes irritated or infected, it fills with excess fluid, producing the hallmark triad of localized pain, swelling, and restricted motion. Common sites in orthopedic practice include the subacromial bursa (shoulder), olecranon bursa (elbow), trochanteric bursa (hip), prepatellar and pes anserine bursae (knee), and retrocalcaneal bursa (ankle/foot).

Etiology drives both clinical management and coding. Repetitive-use bursitis (M70.x codes) results from sustained mechanical overload—common in athletes, manual laborers, and patients with altered gait biomechanics. Infective bursitis (M71.1x codes) requires culture-directed antibiotic therapy in addition to drainage and carries distinct coding and medical-necessity documentation requirements under CMS payer guidelines. Inflammatory or crystal-induced bursitis often co-occurs with gout or rheumatoid arthritis and should be coded with the underlying condition as the principal diagnosis when it drives the encounter.

Treatment ranges from conservative measures (activity modification, NSAIDs, physical therapy) to aspiration, corticosteroid injection, or, in refractory cases, open or arthroscopic bursectomy. Each intervention maps to its own CPT procedure code, and the supporting ICD-10-CM diagnosis must reflect the specific site and laterality documented in the clinical record. Failure to capture those details at the point of care is the single most common cause of claim denial and audit exposure for orthopedic bursitis encounters.

Why it matters

ICD-10-CM contains more than 30 billable bursitis codes differentiated by anatomical site, laterality, and etiology; using an unspecified or non-billable parent code (e.g., M71.57 or M70.5) when a specific lateralized code exists is a documented audit trigger, risks claim denial under CMS medical-necessity requirements for bursal injections, and can cause downstream underpayment because payers—including Medicare—require the most specific code available to adjudicate pain-management injection claims (CPT 20600–20611) correctly.

Common mistakes

Where people most often go wrong with this concept.

Source · Editorial brief grounded in cited references ↓

Assigning a non-billable parent code (e.g., M70.5 or M71.57) instead of the required lateralized child code (e.g., M71.571 for right ankle/foot).
Failing to document laterality in the clinical note, forcing a coder to default to an 'unspecified' code and increasing audit risk.
Coding repetitive-use bursitis (M70.x) and infective bursitis (M71.1x) interchangeably without physician documentation of the causative mechanism or infection status.
Omitting the causative activity in the assessment when bursitis is due to repetitive motion—documentation templates should capture the specific activity and imaging confirmation to satisfy medical-necessity criteria.
Using an unspecified bursitis code (e.g., M71.9) when a site-specific code exists, which conflicts with CMS coverage article requirements for injection procedures and can trigger post-payment audits.
Appending modifier 59 to unbundle injection claims without confirming the procedures are truly distinct and separately identifiable, rather than understanding bundling rules and NCCI edits applicable to same-site injections.

Related codes

Codes commonly involved when this concept appears in practice.

CPT

ICD-10

M70.71 M70.72

Modifiers

59 Distinct procedural service LT Left side RT Right side XS Separate structure 25 Significant separately identifiable E/M 51 Multiple procedures

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 8 cited references ↓

01What is the difference between M70.x and M71.x bursitis codes?

M70.x codes are used for bursitis caused by repetitive use, overuse, or mechanical pressure (occupational or activity-related). M71.x codes cover infective bursitis (M71.1x) and other or unspecified bursitis not attributable to a specific mechanical cause (M71.5x). The physician's documented etiology determines which family of codes applies; coders should not infer etiology without explicit clinical support in the note.

02Why is laterality so important for bursitis coding?

ICD-10-CM requires the most specific code available, and virtually all site-specific bursitis codes have distinct right-side, left-side, and unspecified variants. Using an unspecified code when laterality is documented elsewhere in the record is a coding error that increases audit risk and can result in claim denial under CMS coverage policies that require site-specific diagnosis codes to support injection procedures.

03Which CPT codes are typically used for bursal injections, and what diagnosis codes must support them?

Bursal injections are reported with CPT 20600–20611, selected based on joint or bursa size (small, intermediate, or large) and whether ultrasound guidance (76942) was used. Supporting ICD-10-CM codes must be site-specific and lateralized—for example, M71.552 (other bursitis, left hip) for a left trochanteric bursa injection. CMS's pain-management injection coverage article lists the accepted ICD-10-CM codes; using an unlisted or non-specific code is a common reason for denial.

04When should modifier 25 be appended for a bursitis injection visit?

Modifier 25 is appropriate when a significant, separately identifiable evaluation and management service is performed on the same day as a bursal injection—and the E/M is above and beyond the pre-service work inherent to the procedure. The clinical note must contain distinct documentation supporting the medical decision-making for the E/M component. Modifier 25 is not a mechanism to guarantee payment; it signals that the E/M and procedure are separate, identifiable services.

05Is septic (infective) bursitis coded and treated differently from non-infective bursitis?

Yes. Infective bursitis uses M71.1x codes (e.g., M71.161 for right knee), while non-infective bursitis of the same site uses M71.561. Clinically, infective bursitis requires aspiration for Gram stain and culture plus antibiotic therapy; simple corticosteroid injection is contraindicated until infection is excluded. The distinction has direct reimbursement implications because payers evaluate medical necessity differently for infective versus non-infective bursal procedures.

06Can modifier 59 be used to unbundle two bursal injections billed on the same date of service?

Only if the injections are truly distinct and separately identifiable—for example, injections into anatomically separate bursae. Modifier 59 (or the more granular X-modifiers) cannot be used to bypass NCCI bundling edits when procedures are performed in the same anatomical region or compartment. Practices should review applicable NCCI PTP edits and payer policies before appending modifier 59, as inappropriate use is an OIG-identified audit risk.

Sources & references

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

Mira AI Scribe

MIRA SCRIBE GUIDANCE — BURSITIS ENCOUNTERS When bursitis is the primary or contributing diagnosis, Mira will flag documentation for the following before claim submission: 1. LATERALITY: Every bursitis assessment must specify right, left, or bilateral. 'Hip bursitis' alone maps to a non-specific code; 'right greater trochanteric bursitis' maps to M70.61. Mira will prompt for laterality if it is absent from the note. 2. ETIOLOGY: Distinguish repetitive-use/occupational (M70.x), infective (M71.1x), or other/unspecified (M71.5x). If infection is suspected, document culture results or empirical antibiotic rationale. Mira will surface the etiology field when the assessment contains 'bursitis' without a causative descriptor. 3. INJECTION CODING: When a bursal injection is performed at the same encounter as an E/M service, confirm modifier 25 is documented with a separately identifiable medical decision-making rationale. For multiple same-day injections, Mira will review NCCI PTP edits and flag instances where modifier 59 or X{EPSU} modifiers may—or may not—be appropriate. 4. IMAGING SUPPORT: For repetitive-motion bursitis, documentation of imaging confirmation (ultrasound or MRI) strengthens medical-necessity support under CMS pain-management injection coverage criteria. Mira will note if the imaging reference is missing from the record. 5. SPECIFICITY HIERARCHY: Mira defaults to the most specific billable ICD-10-CM code. If the physician's note supports a specific site and side, the scribe layer will not accept a non-billable parent or unspecified code without a documented clinical reason.

See Mira's approach

Related terms

Tendinopathy Clinical

Tendinopathy is a broad clinical term for degenerative or reactive pathology of a tendon—distinct from acute tendinitis—characterized by pain, swelling, and impaired function without the hallmark inflammatory cell infiltrate of true tendinitis.

Corticosteroid injection Clinical

A corticosteroid injection is an in-office procedure in which a steroid medication—such as triamcinolone acetonide or methylprednisolone acetate—is deposited directly into a joint, bursa, or soft-tissue structure to reduce inflammation and relieve pain. It is billed with a joint-specific CPT code (20600–20611) plus a separate HCPCS drug code for the agent administered.

NCCI (National Correct Coding Initiative) Coding

The National Correct Coding Initiative (NCCI) is a CMS program of automated prepayment edits that prevent Medicare and Medicaid from paying for procedure code combinations that are incorrectly billed together or billed in quantities that exceed what is clinically reasonable.

Medical necessity Compliance

Medical necessity is the standard requiring that a service or item be reasonable and appropriate for diagnosing or treating a patient's condition according to accepted clinical practice. Payers—including Medicare—use this standard to determine whether a claim will be covered and paid.