Q73
Non-Billable (Header)Reduction defects of unspecified limb
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
What This Code Means
Q73 is the ICD-10-CM diagnosis code for reduction defects of unspecified limb. Q73 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering congenital malformations and deformations of the musculoskeletal system (q65-q79).
Header codes like Q73 cannot be reported on claims directly — they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at Q73's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q73 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.