Osteonecrosis and stress-related subchondral injuries in the elite athlete: a review on etiology, clinical signs, and management.

This review examines osteonecrosis (ON) in elite athletes, encompassing bone infarcts (BI) in the medullary canal of the metaphysis or diaphysis and epiphyseal subchondral avascular necrosis (AVN), which is more likely to lead to joint collapse. Unlike in the general population where systemic disease and trauma are primary causes, chronic repetitive microtrauma and stress-related injury are significant contributors in athletes. This review therefore distinguishes between primary ON and secondary ON, which develops on a background of stress or insufficiency fractures, relevant in this population. This review also highlights the paradigm shift in the understanding of "spontaneous osteonecrosis of the knee" (SONK), now recognized as a subchondral insufficiency fracture with secondary ON on the continuum of stress-related injuries rather than as an idiopathic, isolated event. The role of corticosteroids is analyzed, distinguishing the well-established risk from systemic use from the more controversial, incompletely defined link to local intra-articular injections, noting the contraindication of injections in certain pathologies like sesamoid AVN. Finally, this review emphasizes the crucial role of MRI for early detection and staging of ON in elite athletes and the importance of tailored management strategies, which begin with conservative measures but may necessitate career-altering surgical interventions in advanced stages. The prognosis for return to sport is often guarded, underscoring the need for a holistic approach that addresses both biomechanical loading patterns and systemic risk factors.