ACR Appropriateness Criteria® Chronic Knee Pain: Update 2026

Chronic knee pain is prevalent in the adult population and is the most common musculoskeletal complaint in the primary care setting. Although osteoarthritis is the most common etiology of chronic knee pain, other sources include osteochondral lesion, subchondral insufficiency fracture, patellofemoral maltracking, or chronic tendon, meniscus, or ligament abnormalities. Imaging plays a key role in the evaluation of chronic knee pain, noting that the etiology cannot be reliably diagnosed or excluded via physical examination alone. Radiographs are the initial imaging modality of choice for chronic knee pain. If radiographs demonstrate osteoarthritis, this document outlines specific scenarios in which additional imaging may be warranted. This document also discusses the appropriate imaging workup for the other entities described above, including soft tissue abnormalities and subchondral insufficiency fracture. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.