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Difference in Coding Musculoskeletal System Codes in ICD-10-CM

February 15th, 2012

Beginning October 1, 2014, ICD-10-CM will be implemented, taking the place of the ICD-9-CM coding system. ICD-10-CM requires preparation and practice due to its increased specificity levels. In ICD-9-CM, codes pertaining to the musculoskeletal system are dispersed between chapters 13 and 17 which report diseases, diagnoses and injuries. In ICD-10-CM, the majority of the musculoskeletal system codes will now be located within chapters 13 and 19. Also, coding professionals will have to be aware of new modifications and guidelines presented in the new chapters of ICD-10-CM. The guidelines include:

  • Documentation of site and laterality: All codes that have laterality requirements require the coding professional to identify if the disease, injury or diagnosis is located on the right or left region. The necessary sites represent the bone, joint or muscle involved with the diagnosis code. When more than one site is involved in the diagnosis, multiple codes must be used when a multiple sites code is not available. ICD-9-CM lacks site and laterality identification.
  • More specific documentation and coding for fractures: Fracture coding in ICD-10-CM will now require documentation of the type of fracture (displaced or non-displaced), specific site of the fracture, laterality, identification of episode of care, and documentation of open or closed.
  • More specific documentation and coding for injuries: ICD-10-CM is focused on assisting coding professionals in capturing the most specific injury code. The injury codes are organized by the general site of the injury and then by the type of injury involved. The organization of injury type begins with the more superficial injuries and ends with injuries involving the deep body structures.
  • Identification of episode of care: ICD-10-CM will require the use of a seventh character in coding instances such as fractures. This seventh character will identify the patient's encounter of care as follows:
    • Initial encounter for fracture
    • Subsequent encounter for fracture with routine healing
    • Subsequent encounter for fracture with delayed healing
    • Subsequent encounter for fracture with nonunion
    • Subsequent encounter for fracture with mal-union
    • Sequela

      NOTE: It is important that the medical record provides sufficient documentation for the coder to assign the correct seventh character extension.
  • Reorganization of codes: Several codes from various chapters in ICD-9-CM were moved to chapter 13 in ICD-10-CM because of the codes focus on the musculoskeletal system.

The chart below is an example of a patient who appears to have malunion of a fracture and how the malunion would be coded using ICD-9-CM and ICD-10-CM. The ICD-9-CM coding is much less specific with just one code to describe the scenario. ICD-10-CM forces the doctor to use much more specificity and detail within the patient's record.






Malunion of Fracture


Age related osteoporosis with current pathological fracture, unspecified site


Stress fracture, unspecified site


Pathological fracture, unspecified site


Pathological fracture in neoplastic disease, unspecified site


Pathological fracture in other disease, unspecified site

Note: These ICD-10-CM crosswalk codes are only a few examples that are OMS related. To obtain the complete list of the crosswalks related to the ICD-9-CM code 733.81, reference the ICD-10-CM Mappings manual. To obtain a copy of this manual visit the OptumInsight (formerly Ingenix ) website at

A seventh character must be added from one of the following for category M80-M84:

  • A Initial encounter for fracture
  • D Subsequent encounter for fracture with routine healing
  • G Subsequent encounter for fracture with delayed healing
  • K Subsequent encounter for fracture with nonunion
  • P Subsequent encounter for fracture with mal-union
  • S Sequela

For more information on ICD-10-CM and all of its changes, watch the ICD-10-CM and Coding and Billing Workshops pages of the AAOMS web site for information on educational offerings.