Diagnosis and Clinical Assessment of Arthrofibrosis after Total Knee Arthroplasty: Challenges and Evolving Standards.

Arthrofibrosis is a common complication following total knee arthroplasty (TKA), characterized by excessive fibrous tissue formation within the joint, leading to restricted range of motion (ROM), pain, and functional impairment. Accurate diagnosis is essential for distinguishing arthrofibrosis from other causes of postoperative knee stiffness, such as infection, mechanical block, or malalignment. This review aims to explore current diagnostic methods and evolving standards for arthrofibrosis after TKA, focusing on (1) clinical differentiation from other causes of knee stiffness; (2) assessment and diagnostic criteria; (3) imaging, laboratory, and histopathological techniques; and (4) an integrated diagnostic algorithm and future directions. Diagnosis is primarily based on persistent ROM limitation (flexion <90 degrees or extension >5 degrees) for more than 12 weeks, after excluding infection and mechanical causes. Advanced magnetic resonance imaging (MRI) with metal artifact reduction techniques can be used to visualize intra-articular fibrosis, with an MRI-based synovial classification correlating with ROM deficits and severity. Synovial fluid analysis helps rule out infection, and histopathology is employed when the diagnosis remains unclear. The study proposes a stepwise diagnostic algorithm that integrates clinical, imaging, and laboratory findings and discusses future directions for optimizing diagnosis and treatment pathways to improve patient outcomes.