M99.18Subluxation complex (vertebral) of rib cage

M99.18 is the ICD-10-CM diagnosis code for subluxation complex (vertebral) of rib cage. It belongs to category M99 (biomechanical lesions, not elsewhere classified), block M99 (biomechanical lesions, not elsewhere classified) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M99.1 (subluxation complex (vertebral)), M99.18 is specifically for subluxation complex (vertebral) of rib cage. Related codes cover of head region (M99.10), of cervical region (M99.11), of thoracic region (M99.12), of lumbar region (M99.13), of sacral region (M99.14), of pelvic region (M99.15), of lower extremity (M99.16), of upper extremity (M99.17) and 1 more.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 183 (Major Chest Trauma with MCC, relative weight 1.4903), DRG 184 (Major Chest Trauma with CC, relative weight 1.0647), DRG 185 (Major Chest Trauma without CC/MCC, relative weight 0.7715), DRG 963 (Other Multiple Significant Trauma with MCC, relative weight 2.6363), DRG 964 (Other Multiple Significant Trauma with CC, relative weight 1.4972) and DRG 965 (Other Multiple Significant Trauma without CC/MCC, relative weight 1.0059), in MDC 04 (Diseases and Disorders of the Respiratory System) and MDC 24 (Multiple Significant Trauma), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 839.61 (closed dislocation, sternum).