[Anteromedial cortical support reduction in treatment of trochanteric femur fractures: a ten-year reappraisal].

Objective: This review summarized the first 10-year progresses and controversies in the concept of anteromedial cortical support reduction, to provide references for further study and clinical applications. Methods: Relevant domestic and foreign literature on cortical support reduction was extensively reviewed to summarize the definition of positive, neutral, and negative support, anteromedial cortices at the inferior corner, intraoperative technical tips for fracture reduction, radiographic assessment at different periods, comparison between positive versus neutral and medial versus anterior support, and the clinical efficacy of Chang reduction quality criteria (CRQC) and postoperative stability score. Results: Anteromedial cortical support reduction was only focused on the cortex of anteromedial inferior corner, with no concern the status of lateral wall or lesser trochanter. Anteromedial cortex was seldom involved by fracture comminution, it was thicker, denser, and stronger, and was the key for mechanical buttress of the head-neck fragment to share compression load. Positive, neutral, and negative support were also called "extramedullary, anatomic, and intramedullary reduction", respectively. There was hardly seen parallel cortical apposition, but characterized by some kinds of head-neck rotation, for example 10°-15° flexed rotation for positive cortical contact and support. Due to intraoperative compression and postoperative impaction, the status of cortical support may be changed at different time of radiographic examination. The positive medial cortex support was more reliable with less reduction loss than its neutral counterpart, and the anterior cortex contact was more predictive than the medial cortex for final results. As incorporation the bearing of cortex apposition and using a 4-point score, CRQC demonstrated more efficacy and was gradually accepted and applied in the evaluation of trochanteric fracture reduction quality. Postoperative stability score (8 points) provided a assessment tool for early weight-bearing in safety to prevent mechanical failure. Conclusion: Anteromedial cortical support reduction is a key point for stability reconstruction in the treatment of trochanteric femur fractures. Evidence has definitely shown that non-negative (positive and neutral) is superior to negative (loss of cortical support). There is a tendency that positive cortex support is superior to neutral, but high quality study with large sample size is needed for a clear conclusion.