M66.321: Spontaneous rupture of flexor tendons, right upper arm
M66.321, spontaneous rupture of flexor tendons, right upper arm, is listed as a covered diagnosis in 3 Medicare billing and coding articles that apply to 12 HCPCS Level II codes, including G0283 (Electrical stimulation (unattended), to one or more areas…), G0329 (Electromagnetic therapy, to one or more areas for chronic…), G0152 (Services performed by a qualified occupational therapist…). The articles come from 1 Medicare contractor. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with M66.321 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G0283 | Electrical stimulation (unattended), to one or more areas for indication(s) other than wound care, as part of a therapy plan of care | Carrier judgment | — | 2 |
| G0329 | Electromagnetic therapy, to one or more areas for chronic stage iii and stage iv pressure ulcers, arterial ulcers, diabetic ulcers and venous stasis ulcers not demonstrating measurable signs of healing after 30 days of conventional care as part of a therapy plan of care | Carrier judgment | — | 2 |
| G0152 | Services performed by a qualified occupational therapist in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0158 | Services performed by a qualified occupational therapist assistant in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0160 | Services performed by a qualified occupational therapist, in the home health setting, in the establishment or delivery of a safe and effective occupational therapy maintenance program, each 15 minutes | Carrier judgment | — | 1 |
| G2169 | Services performed by an occupational therapist assistant in the home health setting in the delivery of a safe and effective occupational therapy maintenance program, each 15 minutes | Carrier judgment | — | 1 |
| G0281 | Electrical stimulation, (unattended), to one or more areas, for chronic stage iii and stage iv pressure ulcers, arterial ulcers, diabetic ulcers, and venous stasis ulcers not demonstrating measurable signs of healing after 30 days of conventional care, as part of a therapy plan of care | Carrier judgment | — | 1 |
| G0151 | Services performed by a qualified physical therapist in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0157 | Services performed by a qualified physical therapist assistant in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0159 | Services performed by a qualified physical therapist, in the home health setting, in the establishment or delivery of a safe and effective physical therapy maintenance program, each 15 minutes | Carrier judgment | — | 1 |
| G2168 | Services performed by a physical therapist assistant in the home health setting in the delivery of a safe and effective physical therapy maintenance program, each 15 minutes | Carrier judgment | — | 1 |
| L1972 | Ankle foot orthosis, plastic or other material with ankle joint, with or without dorsiflexion assist, prefabricated, off-the shelf | Carrier judgment | — | 1 |
Medicare policy articles listing M66.321
- A53057: Billing and Coding: Home Health Occupational Therapy (Palmetto GBA (HHH MAC); 5 Level II codes). LCD with the same title: L34560
- A53064: Billing and Coding: Outpatient Occupational Therapy (Palmetto GBA (MAC - Part A); 3 Level II codes). LCD with the same title: L34427
- A53058: Billing and Coding: Home Health Physical Therapy (Palmetto GBA (HHH MAC); 6 Level II codes). LCD with the same title: L34564
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other M66 diagnoses (Spontaneous rupture of synovium and tendon)
- M66.322 — Spontaneous rupture of flexor tendons, left upper arm
- M66.311 — Spontaneous rupture of flexor tendons, right shoulder
- M66.312 — Spontaneous rupture of flexor tendons, left shoulder
- M66.331 — Spontaneous rupture of flexor tendons, right forearm
- M66.332 — Spontaneous rupture of flexor tendons, left forearm
- M66.341 — Spontaneous rupture of flexor tendons, right hand
- M66.342 — Spontaneous rupture of flexor tendons, left hand
- M66.351 — Spontaneous rupture of flexor tendons, right thigh
- M66.352 — Spontaneous rupture of flexor tendons, left thigh
- M66.38 — Spontaneous rupture of flexor tendons, other site
- M66.39 — Spontaneous rupture of flexor tendons, multiple sites
- M66.0 — Rupture of popliteal cyst
- M66.111 — Rupture of synovium, right shoulder
- M66.112 — Rupture of synovium, left shoulder
- M66.121 — Rupture of synovium, right elbow
- M66.122 — Rupture of synovium, left elbow
- M66.131 — Rupture of synovium, right wrist
- M66.132 — Rupture of synovium, left wrist
- M66.141 — Rupture of synovium, right hand
- M66.142 — Rupture of synovium, left hand
- M66.144 — Rupture of synovium, right finger(s)
- M66.145 — Rupture of synovium, left finger(s)
- M66.151 — Rupture of synovium, right hip
- M66.152 — Rupture of synovium, left hip
- M66.171 — Rupture of synovium, right ankle
- M66.172 — Rupture of synovium, left ankle
- M66.174 — Rupture of synovium, right foot
- M66.175 — Rupture of synovium, left foot
- M66.177 — Rupture of synovium, right toe(s)
- M66.178 — Rupture of synovium, left toe(s)
Frequently asked questions
Does Medicare cover M66.321 (Spontaneous rupture of flexor tendons, right upper arm)?
Medicare covers items and services, not diagnoses. 3 Medicare billing and coding articles list M66.321 as a covered diagnosis for 12 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 M66.321?
The Level II codes from the policies most specific to this diagnosis are G0283 (Electrical stimulation (unattended), to one or more areas…, 2 articles); G0329 (Electromagnetic therapy, to one or more areas for chronic…, 2 articles); G0152 (Services performed by a qualified occupational therapist…, 1 article); G0158 (Services performed by a qualified occupational therapist…, 1 article); G0160 (Services performed by a qualified occupational therapist…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list M66.321?
A53057 (Billing and Coding: Home Health Occupational Therapy); A53064 (Billing and Coding: Outpatient Occupational Therapy); A53058 (Billing and Coding: Home Health Physical Therapy).
What is ICD-10-CM code M66.321?
M66.321 is the ICD-10-CM code for spontaneous rupture of flexor tendons, right upper arm, in category M66 (Spontaneous rupture of synovium and tendon), chapter 13: Diseases of the musculoskeletal system and connective tissue.
Next steps
- Run a reimbursement report for a device billed under G0283
- Watch G0283 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G0283
Compiled by Caduvo from public CMS (Medicare) records, ICD-10-CM FY2026, HCPCS release October 2026, 2026 fee schedule (non-rural state fees). Not reviewed or endorsed by CMS. Not billing or legal advice. Report an error. Data and corrections policy.
Chapter 13: Diseases of the musculoskeletal system and connective tissue · All diagnoses · HCPCS lookup