ICD-10-CM 2027
ICD-10 code for bone anomaly
From the official ICD-10-CM alphabetic index entry “Anomaly, anomalous (congenital) (unspecified type) › bone”. Page updated September 29, 2026.
About coding bone anomaly
The ICD-10-CM code for bone anomaly is Q79.9 (Congenital malformation of musculoskeletal system, unspecified). The official index lists 9 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on Q79.9.
Within Q79, choose Q79.9 (Congenital malformation of musculoskeletal system, unspecified) only when documentation doesn't support a more specific option: congenital diaphragmatic hernia (Q79.0), other congenital malformations of diaphragm (Q79.1), Exomphalos (Q79.2), gastroschisis (Q79.3), prune belly syndrome (Q79.4), other congenital malformations of abdominal wall (Q79.5), Ehlers-Danlos syndromes (Q79.6) and other congenital malformations of musculoskeletal system (Q79.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC, relative weight 1.4908), DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC, relative weight 0.9783) and DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC, relative weight 0.7378), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific bone anomaly codes (official index)
- arm Q74.0 — Other congenital malformations of upper limb(s), including shoulder girdle
- face Q75.9 — Congenital malformation of skull and face bones, unspecified
- leg Q74.2 — Other congenital malformations of lower limb(s), including pelvic girdle
- pelvic girdle Q74.2 — Other congenital malformations of lower limb(s), including pelvic girdle
- shoulder girdle Q74.0 — Other congenital malformations of upper limb(s), including shoulder girdle
- skull Q75.9 — Congenital malformation of skull and face bones, unspecified
- with
- anencephaly Q00.0 — Anencephaly
- encephalocele
- hydrocephalus Q03.9 — Congenital hydrocephalus, unspecified
- with spina bifida
- microcephaly Q02 — Microcephaly
Common questions about bone anomaly ICD-10 codes
What is the ICD-10 code for bone anomaly?
- Q79.9 — Congenital malformation of musculoskeletal system, unspecified. More specific codes apply when the documentation supports them: Q74.0, Q75.9, Q74.2, Q74.2 and others below.
What is the ICD-10 code for arm bone anomaly?
- Q74.0 — Other congenital malformations of upper limb(s), including shoulder girdle.
What is the ICD-10 code for face bone anomaly?
- Q75.9 — Congenital malformation of skull and face bones, unspecified.
What is the ICD-10 code for leg bone anomaly?
- Q74.2 — Other congenital malformations of lower limb(s), including pelvic girdle.
What is the ICD-10 code for pelvic girdle bone anomaly?
- Q74.2 — Other congenital malformations of lower limb(s), including pelvic girdle.
What is the ICD-10 code for shoulder girdle bone anomaly?
- Q74.0 — Other congenital malformations of upper limb(s), including shoulder girdle.
What is the ICD-10 code for skull bone anomaly?
- Q75.9 — Congenital malformation of skull and face bones, unspecified.
Is Q79.9 billable?
- Yes. Q79.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q79.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q79.9 as a principal diagnosis.
Is Q79.9 a CC or MCC?
- No. Q79.9 is neither a CC nor an MCC under MS-DRG v44.0.