Histopathological examination of post-arthroscopy osteonecrosis of the knee: a scoping review

Background: Post-arthroscopy osteonecrosis of the knee (PONK) was originally described based on magnetic resonance imaging (MRI) findings in the absence of any histopathological evidence. However, several authors have demonstrated the absence of necrosis in histological samples of patients undergoing reoperation after diagnosis of PONK. The aim of this study was to evaluate and synthesize the available literature related to the histopathological characteristics of PONK cases and to determine the appropriateness of related terminology. Methods: A PRISMA-compliant scoping review of PubMed, Scopus, and Cochrane was performed. Studies reporting histological analyses performed on bone samples harvested from patients with a presumptive diagnosis of PONK were included. General study characteristics, radiographic and MRI features, time elapsed between arthroscopy and histological sampling, and results of histological analysis of the bone samples were extracted. Results: Five articles were included, for a total of 22 patients (23 knees, mean age 63.5 years), resulting in 17 bone samples available for histological examination. The most common finding was the presence of subchondral insufficiency fractures (SIF) (94.1%), with necrosis being reported only in one case. Conclusions: Due to the absence of necrosis in most histopathological examinations, the term “PONK” seems inadequate to describe the corresponding clinical condition. Considering the pathological features of the analysed bone samples, SIF should be considered along with PONK when diagnosing and managing these cases until more definitive evidence becomes available.