Individualized indication for slope changing osteotomy in ACL insufficiency: the Avalanche Concept

The management of increased posterior tibial slope (PTS) in anterior cruciate ligament (ACL) injuries and insufficiencies and especially the indication for slope changing osteotomies has evolved to a highly discussed topic. The majority of available studies refer to cut-off values for the PTS and the number of previous ACL reconstructions in their indications. However, ACL injuries are a complex multifactorial problem, and available recommendations mainly ignore these highly individual factors, in their presence, and also in their complexity. Actually, many of the known risk factors for ACL insufficiency are also directly or indirectly associated with PTS. Therefore, the purpose of this paper is to propose a whole new way of thinking about complex ACL treatment strategies by integrating the PTS in a comprehensive approach of individual risk assessment and decision making. It is inspired by an established risk stratification system in a completely different but also very comparable field: avalanches. It is ultimately based on the thorough analysis of individual risk factors and accompanying circumstances on the one hand, and the standardized measured PTS on the other hand. These then define a point on a heat map (in a coordinate system) which, through the underlying colour, reflects the strength of the recommendation for a slope correction. This is to introduce The Avalanche Concept.