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    v1.0.28
    OpenPayerBilling CodesOther joint disordersICD-10-CM m21-other-acquired-deformities-of-limbs
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    ICD-10-CM Code For Other Acquired Deformities Of Limbs: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group M21 includes acquired deformities of the limbs such as malunions, deformities from trauma, acquired valgus or varus deformities, and other noncongenital joint or limb alignment disorders. These ICD-10-CM diagnosis codes are used to document clinical scenarios involving structural limb changes that impact function, mobility, or require corrective procedures, capturing severity and anatomical detail. Accurate coding within the ICD-10-CM M21 group supports proper claim adjudication and complete clinical documentation to substantiate care and reimbursement.

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    ICD-10-CM M21: Other Acquired Deformities Of Limbs Overview

    The ICD-10-CM M21 group captures acquired deformities of the limbs that affect joint alignment, structure, or function rather than congenital anomalies. These diagnoses target musculoskeletal and connective tissue conditions of the arms and legs resulting from injury, disease, or degenerative processes. Accurate coding matters for reimbursement because it documents clinical complexity, supports medical necessity, and informs claims processing.

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    When to Use

    Use a code from this group when a patient has a noncongenital limb deformity documented by clinical exam, imaging, or operative findings that affects alignment or function. Select the most specific code for the type of deformity, laterality, and any associated features such as malunion or nonunion to reflect clinical complexity.

    ICD-10-CM Codes

    124 rows

    ICD-10-CM CodeDescription
    M21.00Valgus deformity, not elsewhere classified, unspecified site
    M21.021Valgus deformity, not elsewhere classified, right elbow
    M21.022Valgus deformity, not elsewhere classified, left elbow
    M21.029Valgus deformity, not elsewhere classified, unspecified elbow
    M21.051Valgus deformity, not elsewhere classified, right hip
    M21.052Valgus deformity, not elsewhere classified, left hip
    M21.059Valgus deformity, not elsewhere classified, unspecified hip
    M21.061Valgus deformity, not elsewhere classified, right knee
    M21.062Valgus deformity, not elsewhere classified, left knee
    M21.069Valgus deformity, not elsewhere classified, unspecified knee
    M21.071Valgus deformity, not elsewhere classified, right ankle
    M21.072Valgus deformity, not elsewhere classified, left ankle
    M21.079Valgus deformity, not elsewhere classified, unspecified ankle
    M21.10Varus deformity, not elsewhere classified, unspecified site
    M21.121Varus deformity, not elsewhere classified, right elbow
    M21.122Varus deformity, not elsewhere classified, left elbow
    M21.129Varus deformity, not elsewhere classified, unspecified elbow
    M21.151Varus deformity, not elsewhere classified, right hip
    M21.152Varus deformity, not elsewhere classified, left hip
    M21.159Varus deformity, not elsewhere classified, unspecified hip

    Showing 1–20 of 124

    DRG Codes

    5 rows

    DRG CodeDescription
    073Cranial and Peripheral Nerve Disorders with MCC
    074Cranial and Peripheral Nerve Disorders without MCC
    564Other Musculoskeletal System and Connective Tissue Diagnoses with MCC
    565Other Musculoskeletal System and Connective Tissue Diagnoses with CC
    566Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC

    Typical Clinical Scenarios

    • An older adult with long-standing osteoarthritic deformity of the knee presents for evaluation of progressive medial joint space collapse, varus alignment, and difficulty ambulating. The patient reports chronic pain, crepitus, and worsening gait instability despite conservative measures; examination shows fixed varus deformity and limited range of motion, prompting assignment of an acquired limb deformity code to document the joint malalignment as an underlying structural problem. Typical codes: M21.36, M21.26, M21.16
    • A pediatric patient previously treated for septic arthritis of the ankle in infancy now presents with growth disturbance and angular deformity of the affected foot, causing shoe fit problems and recurrent soft tissue irritation. The clinic documents the acquired postinfectious deformity as the cause of the current structural abnormality and functional limitation, so a code capturing acquired deformity of the ankle/foot is used when planning orthopedic management. Typical codes: M21.371, M21.372
    • An adult with a history of healed distal femur fracture treated nonoperatively reports progressive malunion with mechanical axis deviation and secondary knee pain; imaging confirms extra-articular malalignment causing early joint degeneration. Because the primary issue is an acquired deformity of the limb from prior trauma contributing to current symptoms and care planning, an acquired deformity code is assigned to capture the malunion as a comorbidity affecting treatment decisions. Typical codes: M21.271, M21.272

    Related Codes

    M20-ACQUIRED-DEFORMITIES-FINGERS-TOES

    ICD-10-CM Code For Acquired Deformities Of Fingers And Toes: Group Overview

    M22-DISORDER-OF-PATELLA

    ICD-10-CM Code For Disorder Of Patella: Group Overview

    M23-INTERNAL-DERANGEMENT-OF-KNEE

    ICD-10-CM Code For Internal Derangement Of Knee: Group Overview

    M24-OTHER-SPECIFIC-JOINT-DERANGEMENTS

    ICD-10-CM Code For Other Specific Joint Derangements: Group Overview

    M25-OTHER-JOINT-DISORDER-NOT-ELSEWHERE-CLASSIFIED

    ICD-10-CM Code For Other Joint Disorder Not Elsewhere Classified: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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