[Positive cortical support reduction in treatment of trochanteric femur fractures: history in theory establishment and its inspiration for clinical innovations].

Reduction is the first step in fracture treatment, and is the predominant factor for treatment outcomes. The positive anteromedial cortical support reduction theory was established by Professor Shi-Min Chang in 2014 for the fixation treatment of trochanteric femur fractures. It was referenced to the nonanatomic reduction theory proposed by Gotfried in 2013 for subcapital femoral neck fractures. Both are nonanatomic cortical support reductions to share medial compressive load, but were just the opposite with each other in the bearing and direction of the proximal head-neck fragment. For femoral neck fractures, positive cortical support means the proximal femoral head-neck fragment is intentionally positioned slightly lateral-superior to the distal neck (less than 1 cortical thickness) and is intramedullarily buttressed by the distal inferior cortex. For trochanteric femur fractures, positive cortical support means the proximal head-neck fragment is deliberately positioned slightly medial-superior to the distal shaft (less than 1 cortical thickness) and is extramedullarily buttressed by the anteromedial cortex of the femoral shaft. Currently positive reduction theory and its derivative Chang reduction quality criterion (CRQC) is widely accepted and practiced worldwide, and are appraised as one of the three keystone theories in the treatment of trochanteric femur fracture, which are tip-apex distance, lateral wall, and cortical support reduction. From the point of scientific methodology, this new theory establishment is related to several important factors, such as identify unusual events in clinical practice, seize the opportunity, abundant knowledge reserves, keep up with the latest progress, conduct analogical reasoning, and promptly summarize the results and publish academic papers.