Is the knee a large or medium joint for billing purposes?

From the Guidelines

For billing purposes, a knee is considered a large joint. This classification is important for medical coding and billing, particularly when documenting procedures such as joint injections, aspirations, or other interventions. The knee is one of the joints categorized as large joints in the human body, along with the hip, shoulder, ankle, elbow, and wrist, as defined by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) 1.

The classification of joints into large, medium, and small is based on the joint's size, complexity, and anatomical significance. The knee is the largest synovial joint in the body and bears substantial weight, consisting of articulations between the femur, tibia, and patella. Understanding this classification is essential for healthcare providers when submitting claims for reimbursement, as procedures performed on large joints typically have different billing codes and reimbursement rates compared to those performed on medium or small joints. Accurate coding ensures proper payment and compliance with billing regulations.

Key points to consider when classifying joints for billing purposes include:

• The ACR and EULAR define large joints as including the shoulders, elbows, hips, knees, and ankles 1
• The knee is a large joint due to its size, complexity, and anatomical significance
• Accurate coding is essential for proper payment and compliance with billing regulations
• Procedures performed on large joints typically have different billing codes and reimbursement rates compared to those performed on medium or small joints

The most recent and highest quality study, published in 2022 by the American Academy of Orthopaedic Surgeons, provides guidance on the management of osteoarthritis of the knee, but does not specifically address the classification of joints for billing purposes 1. However, the study does highlight the importance of accurate diagnosis and treatment of knee osteoarthritis, which is often associated with large joint disease.

In summary, the knee is considered a large joint for billing purposes, and accurate coding is essential for proper payment and compliance with billing regulations. Healthcare providers should consult the most recent and relevant guidelines, such as those published by the ACR and EULAR, to ensure accurate classification and coding of joint procedures.

From the Research

Joint Classification for Billing

• The knee is generally considered a large joint in medical contexts, as seen in studies discussing knee-related procedures and conditions 2.
• This classification is relevant for various medical procedures, including aspiration and injection of the knee joint, as well as total knee arthroplasty 3, 4.

Billing and Coding for Knee Procedures

• The accuracy of ICD-10 coding for revision total knee arthroplasty has been assessed, with results showing that while ICD-10-PCS codes can accurately identify that a revision total knee arthroplasty has occurred, there is inaccuracy in identifying specific revised components 4.
• Cost analyses of Medicare patients undergoing total knee arthroplasty have also been conducted, comparing costs, reimbursements, and net losses for patients with varying complexities 5.

Knee-Related Conditions and Treatments

• Common causes of knee pain include osteoarthritis, patellofemoral pain, and meniscal tears, which can be diagnosed clinically and managed with conservative treatment options 6.
• The knee's susceptibility to acute and overuse injuries, as well as its dependence on ligaments, muscles, and tendons for function, makes it a complex joint to treat 2.