[Research advances on subchondral insufficiency fracture and osteonecrosis of the knee]

To clarify the clinical application of the disease terms "subchondral insufficiency fracture of the knee (SIFK)" and "osteonecrosis of the knee (ONK)", and to review the research progress on this pathological condition.

The research literature in the field of SIFK and ONK both domestically and internationally in recent years was widely reviewed, and the research progress of SIFK and ONK was summarized from the aspects of the current conceptual frameworks, etiological factors and pathogenic mechanisms, clinical and imaging manifestations, therapeutic approaches, and prognostic outcomes.

The exact etiology of SIFK remains controversial, and its specific pathogenesis has not been fully elucidated. Subchondral fracture has been identified as the primary pathological feature of this disease entity. SIFK predominantly affects the females over 65 years old, presenting with sudden onset of severe and persistent pain. MRI serves as the gold standard for diagnosis of early-stage SIFK. The characteristic MRI findings include bone marrow edema-like signals and a subchondral low-signal line in the affected femoral condyle. Generally, if bone morphology is preserved without subchondral bone collapse, conservative management is typically the first-line treatment approach. Surgical intervention should be considered if there is no clinical or radiographic improvement after 3 to 4 months of conservative therapy.

Considering the pathological features of bone specimens, adopting the SIFK for ONK demonstrates greater appropriateness in diagnosis and management of these disorders. Early diagnosis and management are important for improving the prognosis of SIFK patients.