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.
Objective To explore effectiveness of positive support reduction and internal fixation in the treatment of femoral neck fractures. Methods A clinical data of 74 patients with femoral neck fractures treated with hollow screw internal fixation between September 2017 and September 2021 was retrospectively analyzed. Based on the quality of fracture reduction, they were divided into positive support reduction group (group A, n=25), negative support reduction group (group B, n=21), and anatomical reduction group (group C, n=28). There was no significant difference in baseline data such as gender, age, cause of injury, disease duration, fracture side, Garden classification, and fracture line position classification between groups (P>0.05). The occurrence of complications such as early fixation failure, femoral neck shortening, non-union of fractures, and femoral head necrosis in three groups, as well as the Harris score of the hip joint were recorded and compared. Results All patients had primary healing of incisions after operation and were followed up more than 12 months. The follow-up time for groups A, B, and C was (21.1±5.7), (22.6±4.3), and (21.9±4.1) months, respectively; there was no significant difference between groups (P>0.05). There was no significant difference in the incidences of non-union of fractures, early internal fixation failure, and the femoral head necrosis between groups (P>0.05). The incidence and length of femoral neck shortening, and the hip Harris score at last follow-up in groups A and C were all superior to those in the group B, with significant difference (P<0.05). There was no significant difference in the above indicators between groups A and C (P>0.05). Conclusion Positive support reduction can provide a good biomechanical environment for the healing of femoral neck fractures, thereby achieving a higher fracture healing rate, reducing the occurrence of femoral neck shortening, minimizing the function of hip joint, and achieving effectiveness similar to anatomical reduction.
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.
