Interpretation of the 2019 revised version of Association Research Circulation Osseous staging system of osteonecrosis of the femoral head / 中华骨科杂志

ABSTRACT

Osteonecrosis of femoral head (ONFH) has a series of pathological changes and clinical manifestations, including damaged or interrupted blood supply of the femoral head and death of bone marrow and osteocytes. Although subsequent repairing was observed in ONFH, it leads to structural changes or even collapses ultimately. The classification system established by the Association Research Circulation Osseous (ARCO) has been widely used in guiding treatment, estimating prognosis, and evaluating efficacy. In November 2019, 2019 revised version was published on the Journal of Arthroplasty that defined staging system for ONFH developed by an expert group led by Kyung-Hoi Koo, a Korean scholar. It has a great change of ACRO staging system since 1994. The revised ARCO staging system has four-stage system. The features of revised ARCO staging system includes the following items, abolition of stage 0, defining stage I and II as pre-collapse lesions, subgrouping stage III as early and late stage, X-ray evidence of osteoarthritis with accompanying joint space narrowing, acetabular changes and joint destruction classified as stage IV. The revised ARCO staging system simplifies the complexity of the system, but not handles the complexity. Further verification of efficacy and significance of the revised staging system are still required in term of guiding treatment and estimating prognosis.