Practices are still learning how to utilize the ICD-10-CM code set to support the services they perform. Watch for ongoing content published in AAOS Now’s practice management section to help navigate problematic coding issues.


Published 6/1/2018
Sarah Wiskerchen, MBA, CPC

Tips for Utilizing ICD-10-CM

In May 2015, most orthopaedic surgeons and their staff were highly focused on learning the new diagnostic language of ICD-10-CM (International Statistical Classification of Diseases and Related Health Problems, 10th revision, Clinical Modification). That’s because the new diagnosis codes were scheduled to replace ICD-9-CM in October 2015. Three years later, practices are still learning how to utilize the ICD-10-CM code set to support the services they perform. This article outlines five important tips to aid physicians and coders in selecting the appropriate ICD-10-CM codes.

No. 1: Injury codes

Do use chapter 19 injury codes when the documentation states that an injury occurred. Don’t assign pain diagnoses to every orthopaedic claim.

Chapter 19 codes are used for Injury, Poisoning, and Certain Other Consequences of External Causes. These codes are organized first by anatomic body area and then by injury type. Chapter 13 codes are used for Diseases of the Musculoskeletal System and Connective Tissue. These codes are organized by condition type, such as arthropathies, other joint disorders, deforming dorsopathies, spondylopathies, and muscle, synovium, and tendon disorders. Key words such as “current” and “acute” direct code assignment to chapter 19, while terms such as “chronic” or “recurrent” will be found in codes within chapter 13.

A key guideline for chapter 13 states: “Many musculoskeletal conditions are a result of previous injury or trauma to a site, or are recurrent conditions. Bone, joint, or muscle conditions that are the result of a healed injury are usually found in chapter 13. Recurrent bone, joint, or muscle conditions are also usually found in chapter 13. Any current, acute injury should be coded to the appropriate injury code from chapter 19. Chronic or recurrent conditions should generally be coded with a code from chapter 13. If it is difficult to determine from the documentation in the record which code is best to describe a condition, query the provider.”

For example, if a progress note stated that the patient sustained a fall yesterday, and now has right knee pain, under this guideline it would be incorrect to assign a right knee pain diagnosis because it falls within chapter 13 (M25.561). Instead, the physician should assign the most specific injury diagnosis, even if part of the description uses the term unspecified. Examples might include contusion, sprain, strain, or unspecified injury of the right lower limb, depending on the examination findings.

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No. 2: ICD-10-CM default codes

Do learn which ICD-10-CM default codes apply when the documentation does not specify whether a problem is acute or chronic. Don’t leave it up to a coder to make the assignment.

Just as in ICD-9-CM, some body areas have parallel codes for acute injuries and chronic conditions, and the physician’s documentation determines which code is used. For example, chapter 19 includes four categories of current meniscal injury: bucket handle tears, peripheral tears, complex tears, and other tears. These tear types are further delineated by the medial or lateral meniscus and knee laterality, right, left, or unspecified. In contrast, chapter 13 includes three meniscus condition categories: cystic meniscus, derangement of meniscus due to old tear or injury, and other meniscus derangements. The codes are further delineated by the medial or lateral meniscus, the anterior or posterior horn, and laterality.

If a provider’s note does not specify whether the patient has a current meniscal injury, or that a chronic condition exists, the coder must rely on the ICD-10-CM default code to make the code assignment. The default is identifiable within the ICD-10-CM index as the first listed item.

Tear, torn
Meniscus (knee) (current injury) S83.209

Within the shoulder, similar parallel codes exist for the rotator cuff. Chapter 19 includes rotator cuff strains in category S46, and the codes are next delineated by laterality. Chapter 13 includes rotator cuff tear or rupture that is not specified as traumatic in the category M75. The codes are defined as “incomplete” or “complete” and also reflect laterality. In the case of the rotator cuff, the default is the chapter 13 option, which is different than the meniscal tear finding.

Tear, torn
Rotator cuff (nontraumatic) M75.10-

Physicians should always include an Indications for Surgery paragraph within their operative notes, and use that section to specify whether current/acute or chronic/recurrent status applies.

No. 3: Payer medical necessity policies

Do research payer medical necessity policies for the services you perform, and be prepared to educate patients that they may bear some financial responsibility. Don’t assign ICD-10-CM codes that are not supported in the patient’s record.

Remember the phrase, “CPT codes describe what you did, and ICD-10-CM codes describe why you did it.” Payers may set their reimbursement rates using CPT codes, but they determine whether services are payable based on medical necessity factors, including ICD-10-CM codes. Medical necessity assessments begin with surgical precertification, but are also impacted by claims adjudication, and documentation can be reviewed retrospectively. Even when claims are paid, monies can be recouped if reviews find that medical necessity criteria were not met.

No. 4: Comorbid condition diagnoses

Do use comorbid condition diagnoses that impact your treatment of the patient and reflect the complicated nature of the patient. Don’t assign diagnoses for every problem that the patient has listed in his or her history or problem list.

It is not appropriate for a coder to search the hospital record for comorbid diagnoses that the physician did not document within the operative note, or to search the past medical history for diagnoses that are not pertinent to the day’s visit. What is appropriate? Use the Indications for Surgery paragraph or the Assessment section of the office note to make the connection between comorbidities and the service being provided. With respect to surgery, the comorbidity may add to the complexity of the case, or represent the potential for complications that could require a return to the operating room or extended postoperative care. In the office setting, the comorbidity may contribute to higher risk when determining the medical decision-making component of the evaluation and management code. It’s essential that the physician’s documentation show the connection between the comorbid condition and the medical decision-making.

Although current fee-for-service reimbursement methods may not recognize comorbidity code assignment, developments in bundled payment and risk sharing are altering this model. Comorbidity reporting is already an integral part of Hierarchical Condition Categories, which are used to set capitated payments for Medicare Advantage plans.

No. 5: External cause codes

Do use external cause codes when they are either required by a payer or contribute to explaining the circumstances of postsurgical problems. Don’t task your staff with assigning external cause codes to every injury claim.

External cause codes are ICD-10-CM codes that begin with letters V, W, X, and Y, and they are used to describe various circumstances of injury. Although primarily used for injury research and evaluation of injury prevention strategies, some payers, such as worker’s compensation plans, require external cause codes in addition to the injury diagnoses because they help to determine financial responsibility for claims. The codes fall within four primary sections: transport accidents, falls, exposure, and other.

Within orthopaedics, describing the circumstances of a patient’s fall may help to explain postsurgical factors that are not related to the surgery. For example, if a patient falls out of bed after a total hip arthroplasty and dislocates, that status is important to report, because the dislocation could otherwise be considered a complication after surgery.

Although we’re all for correct coding, taking time to assign external cause codes when they are not required is labor intensive and does not improve payment.

To find out how to learn more about these and other ICD-10-CM coding tips at an AAOS Coding & Reimbursement Workshop, visit

Sarah Wiskerchen, MBA, CPC, is a senior consultant with KarenZupko & Associates, Inc. Information in this article has been reviewed by the members of the AAOS Coding, Coverage, and Reimbursement Committee.