M21.861: Other specified acquired deformities of right lower leg
M21.861, other specified acquired deformities of right lower leg, is listed as a covered diagnosis in 3 Medicare billing and coding articles that apply to 60 HCPCS Level II codes, including G0283 (Electrical stimulation (unattended), to one or more areas…), L1844 (Knee orthosis, single upright, thigh and calf, with…), L1860 (Knee orthosis, modification of supracondylar prosthetic…). 47 of these codes have a 2026 DMEPOS fee schedule amount; L1844 pays $1,865.51 to $2,436.24 depending on the state. The articles come from 2 Medicare contractors. 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 M21.861 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 |
| L1844 | Knee orthosis, single upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, custom fabricated | Carrier judgment | $1,865.51–$2,436.24 | 1 |
| L1860 | Knee orthosis, modification of supracondylar prosthetic socket, custom fabricated (sk) | Carrier judgment | $1,233.07–$1,985.94 | 1 |
| L1846 | Knee orthosis, double upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, custom fabricated | Carrier judgment | $1,283.72–$1,960.17 | 1 |
| L1834 | Knee orthosis, without knee joint, rigid, custom fabricated | Carrier judgment | $892.02–$1,808.36 | 1 |
| L1832 | Knee orthosis, adjustable knee joints (unicentric or polycentric), positional orthosis, rigid support, prefabricated item that has been trimmed, bent, molded, assembled, or otherwise customized to fit a specific patient by an individual with expertise | Carrier judgment | $698.63–$1,618.03 | 1 |
| L1840 | Knee orthosis, derotation, medial-lateral, anterior cruciate ligament, custom fabricated | Carrier judgment | $1,056.60–$1,606.15 | 1 |
| L1843 | Knee orthosis, single upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, prefabricated item that has been trimmed, bent, molded, assembled, or otherwise customized to fit a specific patient by an individual with expertise | Carrier judgment | $1,076.26–$1,183.90 | 1 |
| L1845 | Knee orthosis, double upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, prefabricated item that has been trimmed, bent, molded, assembled, or otherwise customized to fit a specific patient by an individual with expertise | Carrier judgment | $939.24–$1,180.51 | 1 |
| L1833 | Knee orthosis, adjustable knee joints (unicentric or polycentric), positional orthosis, rigid support, prefabricated, off-the shelf | Carrier judgment | $455.16–$1,087.16 | 1 |
| L1851 | Knee orthosis (ko), single upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, prefabricated, off-the-shelf | Carrier judgment | $600.78–$959.09 | 1 |
| L1852 | Knee orthosis (ko), double upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, prefabricated, off-the-shelf | Carrier judgment | $573.13–$940.49 | 1 |
| L2330 | Addition to lower extremity, lacer molded to patient model, for custom fabricated orthosis only | Carrier judgment | $429.42–$904.14 | 1 |
| L1847 | Knee orthosis, double upright with adjustable joint, with inflatable air support chamber(s), prefabricated item that has been trimmed, bent, molded, assembled, or otherwise customized to fit a specific patient by an individual with expertise | Carrier judgment | $689.92–$827.89 | 1 |
| L1848 | Knee orthosis, double upright with adjustable joint, with inflatable air support chamber(s), prefabricated, off-the-shelf | Carrier judgment | $689.92–$827.89 | 1 |
| L1850 | Knee orthosis, swedish type, prefabricated, off-the-shelf | Carrier judgment | $205.78–$408.53 | 1 |
| L2820 | Addition to lower extremity orthosis, soft interface for molded plastic, below knee section | Carrier judgment | $99.79–$399.72 | 1 |
| L2830 | Addition to lower extremity orthosis, soft interface for molded plastic, above knee section | Carrier judgment | $107.96–$399.72 | 1 |
| L1831 | Knee orthosis, locking knee joint(s), positional orthosis, prefabricated, includes fitting and adjustment | Carrier judgment | $353.04–$388.33 | 1 |
| L2320 | Addition to lower extremity, non-molded lacer, for custom fabricated orthosis only | Carrier judgment | $236.44–$325.94 | 1 |
| L2395 | Addition to lower extremity, offset knee joint, heavy duty, each joint | Carrier judgment | $76.15–$251.19 | 1 |
| L2390 | Addition to lower extremity, offset knee joint, each joint | Carrier judgment | $76.15–$227.94 | 1 |
| L2385 | Addition to lower extremity, straight knee joint, heavy duty, each joint | Carrier judgment | $51.03–$225.93 | 1 |
| E1810 | Dynamic adjustable knee extension and flexion device, includes soft interface material | Carrier judgment | $142.48–$222.55 (RR) | 1 |
| E1813 | Dynamic adjustable knee extension only device, includes soft interface material | Carrier judgment | $142.48–$222.55 (RR) | 1 |
35 more codes are listed. See every code with payment by region in Caduvo.
Medicare policy articles listing M21.861
- A52465: Knee Orthoses - Policy Article (CGS Administrators, LLC (DME MAC) Noridian Healthcare Solutions, LLC (DME MAC); 53 Level II codes). LCD with the same title: L33318
- 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
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 M21 diagnoses (Other acquired deformities of limbs)
- M21.862 — Other specified acquired deformities of left lower leg
- M21.831 — Other specified acquired deformities of right forearm
- M21.832 — Other specified acquired deformities of left forearm
- M21.071 — Valgus deformity, not elsewhere classified, right ankle
- M21.072 — Valgus deformity, not elsewhere classified, left ankle
- M21.171 — Varus deformity, not elsewhere classified, right ankle
- M21.172 — Varus deformity, not elsewhere classified, left ankle
- M21.331 — Wrist drop, right wrist
- M21.332 — Wrist drop, left wrist
- M21.371 — Foot drop, right foot
- M21.372 — Foot drop, left foot
- M21.511 — Acquired clawhand, right hand
- M21.512 — Acquired clawhand, left hand
- M21.531 — Acquired clawfoot, right foot
- M21.532 — Acquired clawfoot, left foot
- M21.541 — Acquired clubfoot, right foot
- M21.542 — Acquired clubfoot, left foot
- M21.6X1 — Other acquired deformities of right foot
- M21.6X2 — Other acquired deformities of left foot
- M21.751 — Unequal limb length (acquired), right femur
- M21.752 — Unequal limb length (acquired), left femur
- M21.761 — Unequal limb length (acquired), right tibia
- M21.762 — Unequal limb length (acquired), left tibia
- M21.763 — Unequal limb length (acquired), right fibula
- M21.764 — Unequal limb length (acquired), left fibula
- M21.961 — Unspecified acquired deformity of right lower leg
- M21.962 — Unspecified acquired deformity of left lower leg
Frequently asked questions
Does Medicare cover M21.861 (Other specified acquired deformities of right lower leg)?
Medicare covers items and services, not diagnoses. 3 Medicare billing and coding articles list M21.861 as a covered diagnosis for 60 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 M21.861?
The Level II codes from the policies most specific to this diagnosis are G0283 (Electrical stimulation (unattended), to one or more areas…, 2 articles); L1844 (Knee orthosis, single upright, thigh and calf, with…, 1 article); L1860 (Knee orthosis, modification of supracondylar prosthetic…, 1 article); L1846 (Knee orthosis, double upright, thigh and calf, with…, 1 article); L1834 (Knee orthosis, without knee joint, rigid, custom fabricated, 1 article). Code choice depends on the item supplied; check each code's descriptor.
What does Medicare pay for equipment billed with M21.861?
Under the 2026 DMEPOS fee schedule (non-rural state fees): L1844 $1,865.51 to $2,436.24; L1860 $1,233.07 to $1,985.94; L1846 $1,283.72 to $1,960.17; L1834 $892.02 to $1,808.36. Medicare pays 80% of the allowed amount after the Part B deductible.
Which Medicare policy articles list M21.861?
A52465 (Knee Orthoses - Policy Article); A53057 (Billing and Coding: Home Health Occupational Therapy); A53064 (Billing and Coding: Outpatient Occupational Therapy).
What is ICD-10-CM code M21.861?
M21.861 is the ICD-10-CM code for other specified acquired deformities of right lower leg, in category M21 (Other acquired deformities of limbs), 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
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 13: Diseases of the musculoskeletal system and connective tissue · All diagnoses · HCPCS lookup