ICD-10-CM Basics for Orthopaedics

Editor’s note: AAOS partners with KarenZupko & Associates, Inc. (KZA) on the organization’s coding education, and KZA often provides content for AAOS Now. For more information, visit aaos.org/membership/coding-and-reimbursement.

Why does diagnosis coding accuracy make a difference? ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification) diagnosis codes are used by clinicians, coders, and insurance providers to support the medical necessity of the services performed and measure the complexity of patients treated. Hospitals use ICD-10 diagnosis codes to determine the appropriate diagnosis-related groups (DRGs) for inpatient services. The codes are also used for clinical research. Current Procedural Terminology (CPT) codes explain the services provided to the patient, whereas ICD-10-CM codes explain why the services were performed.

From a clinical standpoint, proper diagnosis coding starts with documentation. As more clinicians are relying upon electronic medical records (EMRs) to assist in selecting diagnosis codes and the implementation of artificial intelligence (AI) to extract the data, it is important to document the definitive diagnosis and/or the patient’s symptoms to the greatest specificity.

Here are a few important reasons why diagnosis coding accuracy is crucial to orthopaedic practice:

• Diagnosis codes help to provide a complete picture of the patient’s health, and relevant comorbidities should be included in the record to demonstrate the severity of the patient’s condition and the risks of treatment (e.g., smoking, diabetes, methicillin-resistant Staphylococcus aureus).
• Proper diagnosis documentation and code selection support medical necessity for prior authorizations and treatments. If diagnosis coding is not supported with appropriate documentation, healthcare providers may not get paid for work performed.
• Medicare and commercial insurance policies contain diagnosis coverage criteria (a list of diagnoses) for payment.
• Diagnosis codes are valuable, as they provide clarity regarding the severity of a condition and contribute to other areas of healthcare such as research outcomes.
• Insurance companies expect that the diagnosis reported on the claim is consistent with the condition and the treatment rendered.

Updates to ICD-10-CM occur annually on Oct. 1 each year. However, quarterly updates may also occur as needed depending on other government source information. ICD-10-CM codes consist of three to seven characters, and every code begins with an alphabetical character followed by two to six numeric characters. The official ICD-10-CM classification includes three main sections: the official ICD-10-CM guidelines, the indexes, and the tabular list.

Although Chapters 13 and 19 are where most orthopaedic codes are listed, all codes throughout the ICD-10-CM book are available when indicated and supported within the documentation.

Chapter 13, Diseases of the Musculoskeletal System and Connective Tissue (M00–M99), contains specific guidelines applicable to orthopaedics. It also contains information regarding site and laterality, acute traumatic versus chronic or recurrent musculoskeletal conditions, coding of pathologic fractures, and osteoporosis with or without current pathological fractures.

The second chapter applicable to orthopaedics is Chapter 19, Injury, Poisoning, and Other External Causes (S00–T88). Chapter 19 contains information on the appropriate application of 7th characters (e.g., A, D, S, etc.); coding of injuries; traumatic fractures; complications of care; burns and corrosions; adverse effects; poisoning; underdosing and toxic effects; and adult and child abuse, neglect, and other maltreatment.

Ensure documentation to the highest level of specificity known at the time of the encounter, including the following information:

• location and laterality—a must for orthopaedics
• if supported, state more than “arthritis” (e.g., rheumatoid arthritis, post-traumatic arthritis, secondary)
• whether the condition being treated is acute or chronic—again, a must for orthopaedics
• whether a complication is being treated, as this may make a difference in code selection
• whether a patient is affected by social determinants of health, which can also affect the overall evaluation and management code level selection
• signs and symptoms—only to be assigned when a definitive diagnosis has not yet been established or when additional signs and symptoms are present and are not an integral part of a disease process being addressed or treated
• injury coding by initial (A), subsequent (D), or sequela (S)
• Z codes
  • Follow-up Z codes are used only for visits when the condition is totally treated, resolved, or healed (e.g., total joint surveillance visits).
  • Aftercare Z codes explain ongoing care of a healing condition or its sequelae (residual effect). However, they should not be used for injury aftercare. For injury aftercare, assign the acute injury code the appropriate 7th character S (subsequent encounter).

The Alphabetic Index contains the Index of Diseases and Injury and includes tables for the External Causes of Injury, the Table of Neoplasms, and the Table of Drugs and Chemicals. These indexes are designed to help users streamline the process of locating the necessary diagnosis codes.

Lastly, the Tabular List is the actual listing of ICD-10-CM codes and the descriptors of each code. Within the Tabular List, users can find instructions on how to apply the codes correctly, lists of additional diagnoses applicable to a code, sequencing rules, and ICD-10-CM codes excluded from a particular diagnosis code. The Tabular List is organized into 22 chapters according to body system or condition, with diagnosis codes listed alphanumerically in each chapter.

What can orthopaedic professionals do to stay current on ICD-10-CM updates? Make sure that one’s practice, including all billing and coding staff, remains up to date yearly. To do this, ensure that EMR and practice-management systems are updated annually (Oct. 1 each year), including any new, revised, or deleted codes that are applicable to the practice. Perform internal audits for diagnosis coding accuracy and provide education to clinicians and clinical staff when needed. Lastly, a direct feedback loop between the revenue team and practitioners and clinicians should be created to tackle revenue leaks, such as claim denials for the use of unlisted diagnosis codes, codes that do not support medical necessity, or any other diagnosis coding errors.

For a complete listing of the ICD-10-CM conventions, general coding, and chapter-specific guidelines, see the 2024 ICD-10-CM.

KZA looks forward to welcoming AAOS members and other orthopaedic professionals at one of its national AAOS Coding and Reimbursement Workshops in 2024. Learn more at kzanow.com.

Marissa Clemmer, CPC, CCS, CPMA, CPB, CANPC, CPEDC, is a consultant with KZA and is an instructor at the AAOS reimbursement and coding workshops.