ABSTRACT
<p><b>OBJECTIVE</b>To investigate the biomechanical stability of the acetabular fracture with three different internal fixation methods.</p><p><b>METHODS</b>Sixteen both-column acetabular fracture models were randomly divided into three groups:The specimens of 16 hip joints were randomly divided into 4 groups. Among them, 1 group of complete acetabulum were used as normal control group, and the other 3 groups simulated two column fracture models and were fixed in the following methods, respectively: anterior wall with screw and posterior with plate(SP), anterior wall with plate and posterior wall with screw(PS) and both wall with plate (PP). The degree of fracture displacement and the contact characteristics of the acetabulum were recorded by continuous vertical loading.</p><p><b>RESULTS</b>The mean longitudinal displacement under the load 800 N of SP, PS and PP three groups were (1.92±0.81), (2.09±1.13) and (3.44±0.75) mm, there was significant difference between SP and PP group (0.033). And the mean horizontal displacement of SP, PS and PP three groups were(0.63±0.33), (0.77±0.45) and (1.44±0.56) mm, there was significant difference between SP and PP group(0.047).Compared with normal control group in the acetabular area under the loading 800 N, the contact area of SP, PS and PP groups were increased by 6%, 9% and 27%, there was significant difference between PP and normal control group (0.027). Meanwhile, the mean stress of SP, PS and PP groups were increased by 4%, 29% and 39%, there was significant difference between PP and intact acetabulum group (0.003).</p><p><b>CONCLUSIONS</b>Anterior column screw combined with posterior column plate has better biomechanical stability and contact characteristics than other two methods.</p>
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the causes of delayed union or nonunion of the ulna after intramedullary nailing in pediatric forearm fractures.</p><p><b>METHODS</b>From February 2005 to February 2010,5 patients with forearm fractures who were treated with titanium elastic nailing (TEN) were identified to fulfill the criteria of having developed a delayed union or nonunion of the ulna. The causes of delayed union or nonunion were investigated according to mechanism of injury, fracture location, treatments methods and postoperative management. All patients were male and the age was 3 to 14 years old with an average of 9.4 years. All fractures were located on the mid-third part of forearm. Two cases had a re-fracture. Among them, 3 cases caused by high-energy injury and 2 cases by falling down. Open reduction were performed in 4 cases while the other one was treated with closed reduction. Four patients were immobilized in an above-elbow cast, postoperatively.</p><p><b>RESULTS</b>All patients were followed up from 7 to 19 months with an average of 11.4 months. There were 4 delayed union and 1 nonunion. Three patients healed after the removal of the nail and avoidance of weight-bearing. Two patients healed by replacing another fixation. No patients had soft-tissue irritation or nail-entry-site infections.. The clinical effect was evaluated according to Daruwalla and Price scores with 3 excellent and 2 good of the results.</p><p><b>CONCLUSIONS</b>Using titanium elastic nailing for the treatment of pediatric both-bone forearm fractures is a good method. However,strict indication selection should be followed to avoid delayed union or nonunion.</p>