T84.033AMechanical loosening of internal left knee prosthetic joint, initial encounter

T84.033A is the ICD-10-CM diagnosis code for mechanical loosening of internal left knee prosthetic joint, initial encounter. It belongs to category T84 (complications of internal orthopedic prosthetic devices, implants and grafts), block T80-T88 (complications of surgical and medical care, not elsewhere classified) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

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 559 (Aftercare, Musculoskeletal System and Connective Tissue with MCC, relative weight 1.8088), DRG 560 (Aftercare, Musculoskeletal System and Connective Tissue with CC, relative weight 1.1238) and DRG 561 (Aftercare, Musculoskeletal System and Connective Tissue without CC/MCC, relative weight 0.8258), 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.

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 996.41 (mechanical loosening of prosthetic joint).