M75.91

Unspecified lesion of the right shoulder — used when a specific soft-tissue shoulder diagnosis cannot be established at the time of coding.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Shoulder

Drawn from CDCICD10DataAAPCCMSIcdlist

Documentation tips

What should appear in the chart to support M75.91.

Source · Editorial brief grounded in 5 cited references ↓

Explicitly document laterality as 'right shoulder' — M75.91 is laterality-specific and cannot be used if side is undocumented.
Record why a specific diagnosis has not yet been established: e.g., 'imaging pending,' 'clinical picture unclear at this visit,' or 'rule-out rotator cuff pathology.'
Once MRI or ultrasound results return, update the diagnosis to the most specific M75 code supported by the findings — do not carry M75.91 forward indefinitely.
Document any specific structures evaluated (rotator cuff, biceps tendon, bursa, capsule) and why each was ruled out or remains indeterminate.
If the record contains a specific diagnosis elsewhere (e.g., impingement syndrome), do not code M75.91 — use M75.41 for right shoulder impingement instead.

Related CPT procedures

Procedure codes commonly billed with M75.91. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

29827 $976.31

Arthroscopic surgical repair of the rotator cuff, performed entirely through the shoulder joint via endoscopic technique.

29826 $147.63

Arthroscopic shoulder surgery to decompress the subacromial space, including partial reshaping of the acromion and release of the coracoacromial ligament when performed. Add-on code — always listed in addition to a primary shoulder arthroscopy code.

29823 $558.80

Arthroscopic surgical debridement of the shoulder involving three or more discrete anatomic structures.

29824 $638.96

Arthroscopic resection of the distal clavicle including its articular surface, performed at the acromioclavicular joint (the Mumford procedure).

29819 $550.11

Arthroscopic shoulder surgery for removal of loose or foreign bodies from the joint

73221 $205.08

MRI of any upper extremity joint — shoulder, elbow, or wrist — performed without contrast material.

73222 $312.63

MRI of an upper extremity joint performed with contrast material — covers shoulder, elbow, wrist, or hand joints.

20610 $68.81

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

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.

73223 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M75.91 and adjacent codes.

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

Using M75.91 when a specific M75 subcategory is clearly supported by documentation — impingement (M75.41), bursitis (M75.51), rotator cuff tear (M75.101–M75.121), bicipital tendinitis (M75.21), or calcific tendinitis (M75.31) must each be coded specifically.
Confusing M75.91 (unspecified lesion, right shoulder) with M75.81 (other shoulder lesions, right shoulder) — M75.81 is used when a named lesion is present but doesn't fit a specific subcategory; M75.91 is used when the lesion itself is unclassified.
Applying M75.91 to a traumatic shoulder injury — acute injuries require S-codes with the appropriate 7th-character encounter extension (A, D, or S), not M-codes.
Leaving M75.91 on the claim after a definitive diagnosis is established, which can trigger payer audits for medical necessity and denial on specificity grounds.
Forgetting that shoulder-hand syndrome (M89.0-) is excluded from the M75 category and requires its own code regardless of right-side involvement.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M75.91 is a last-resort code within the M75 (Shoulder lesions) category. Use it only when the provider has documented a right shoulder abnormality but the clinical workup has not yet identified a specific condition — such as rotator cuff pathology, bicipital tendinitis, calcific tendinitis, impingement syndrome, bursitis, or adhesive capsulitis. Each of those conditions has a dedicated, more specific M75 code that must be used instead whenever the diagnosis supports it.

The code groups into MS-DRG 557 (Tendonitis, myositis and bursitis with MCC) and 558 (without MCC), so it does carry reimbursement weight. However, many commercial payers flag or deny unspecified codes when more specific alternatives exist. If the provider documents 'right shoulder tendinitis' or 'supraspinatus tendinitis,' code M75.31 (calcific tendinitis, right shoulder) or the appropriate rotator cuff code instead — M75.91 does not belong on that encounter.

M75.91 is appropriate during an initial workup visit where imaging is pending and the provider can only state that a lesion is present in the right shoulder. Once imaging results confirm a specific pathology, update the code on subsequent encounters. Never use M75.91 as a permanent placeholder when a definitive diagnosis is documented elsewhere in the record.

Sibling codes

Other billable codes under M75.9 (laterality / anatomic variants).

M75.92

Shoulder lesion, unspecified, left shoulder

M75.90

Shoulder lesion, unspecified, unspecified shoulder

Frequently asked questions

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

01When is M75.91 the correct code instead of a more specific M75 code?

Use M75.91 only when the provider has identified a right shoulder abnormality but cannot yet classify it as impingement, bursitis, rotator cuff pathology, tendinitis, or another named condition. The moment a specific diagnosis is documented or confirmed by imaging, switch to the appropriate M75 subcategory code.

02Can M75.91 be used for a traumatic right shoulder injury?

No. Acute traumatic shoulder injuries — strains, dislocations, tears caused by a specific incident — require S-codes with 7th-character extensions (A for initial encounter, D for subsequent, S for sequela). M75.91 covers soft-tissue lesions that are not classified as traumatic.

03What is the difference between M75.81 and M75.91?

M75.81 (other shoulder lesions, right shoulder) is used when a named or identified lesion doesn't fit any specific M75 subcategory. M75.91 is used when the lesion itself is unclassified — the nature of the pathology is unknown, not just the category.

04Will payers reimburse M75.91, or do they require a more specific code?

M75.91 is billable and groups into MS-DRG 557/558, but many commercial payers flag unspecified codes. Document the clinical reason specificity isn't available. Some payers will deny or downpay claims where a specific M75 code is supported by the record but M75.91 was coded instead.

05If the provider documents 'right shoulder tendinitis' without naming the tendon, what code is correct?

Query the provider for the specific tendon involved. If the note supports supraspinatus involvement, use M75.31 (calcific tendinitis, right shoulder) or the appropriate rotator cuff code. Generic 'right shoulder tendinitis' without further detail may support M75.91 as a temporary code, but specificity should be pursued before submission.

06Is M75.91 appropriate for a follow-up visit after right shoulder surgery when the specific post-op diagnosis is known?

No. Post-operative follow-up with a documented diagnosis — such as a repaired rotator cuff tear — should be coded to the specific condition (e.g., M75.121 for complete right rotator cuff tear). M75.91 is inappropriate once the underlying pathology is established.

07Does M75.91 require a 7th-character extension?

No. M75.91 is an M-code (musculoskeletal disease code), not an injury S-code. 7th-character extensions (A/D/S for encounter type) apply to injury codes, not to M75 category codes.

Sources & references

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

Mira AI Scribe

Mira's AI scribe captures right-side laterality, the provider's statement that a specific diagnosis has not been established, and any notation that imaging or further workup is pending — the details that justify M75.91 over a more specific M75 code. Without that documentation, a payer audit may reject the unspecified code or a coder may default to a less defensible selection.

See how Mira captures M75.91 documentation