Objective To investigate the effectiveness of cannulated lag screws combined with lateral supporting plates in the treatment of Hoffa fracture of Letenneur type I and type III. Methods Between May 2004 and April 2011, 11 patients with Hoffa fracture of Letenneur type I and type III were treated, including 6 males and 5 females with an average age of 36 years (range, 25-47 years). Factures were caused by traffic accident in 8 cases, by falling in 2 cases, and by the other in 1 case. Fracture involved the left knee in 7 patients and the right knee in 4 patients. According Letenneur’s classification criteria, there were 7 type I fractures (6 lateral condyle fractures and 1 medial condyle fracture) and 4 type III fractures (3 lateral condyle fractures and 1 medial condyle fracture). Of 11 fractures, 9 were fresh fractures and 2 were old fractures. Two 6.5 mm cannulated lag screws combined with lateral supporting plates were used to fix fractures by anterolateral or anteromedial incision. Results All incisions achieved primary healing with no early complication. All patients were followed up 12-26 months (mean, 15 months). X-ray films showed bone healing with an average healing time of 15 weeks (range, 10-18 weeks). No loosening or breaking of internal fixator was observed; the removal time of internal fixation was 9-15 months (mean, 12 months). Accoding to Letenneur’s functional assessment system, the results were excellent in 7 cases, good in 3 cases, and poor in 1 case at last follow-up. Conclusion Cannulated lag screws combined with lateral supporting plates fixation is effective in treatment of Hoffa fracture of Letenneur type I and type III with a high union rate; anterolateral or anteromedial approach is the first choice for Hoffa fracture of type I and type III, especially for complicating by tibial plateau fracture or patella fracture.
Objective To investigate the effectiveness and the advantage of fixation with percutaneous cannulated screws assisted by robot navigation in the treatment of femoral neck fractures by comparing with the conventional surgery. Methods Between January 2013 and December 2014, 20 patients with femoral neck fracture were treated by internal fixation with percutaneous cannulated screws assisted by robot navigation (navigation group), another 18 patients undergoing conventional surgery with manual positioning were chosen as the control group. There was no significant difference in gender, age, cause of injury, the injury side, time from injury to operation, and the classification of fractures between 2 groups (P > 0.05). The operation time, X-ray fluoroscopy time, blood loss, frequency of guide pin insertion, and healing time were recorded. At 1 week after operation, the parallel degree of screws was measured on the anteroposterior and lateral X-ray films; the Harris score was used to evaluate the hip function. Results All incisions of 2 groups healed by first intention after operation. There was no significant difference in operation time between 2 groups (t= -1.139, P=0.262). The blood loss, frequency of guide pin insertion, and X-ray fluoroscopy time of navigation group were significantly less than those of control group (P < 0.05). There were 2 screws penetrating into the joint cavity in control group. The patients were followed up 12-24 months with an average of 18 months. The navigation group got significantly better parallel degree of screws than control group on the anteroposterior and lateral X-ray films (t=25.021, P=0.000; t=18.659, P=0.000). Fractures healed in all patients of navigation group (100%), and the healing time was (21.8±2.8) weeks; fracture healed in 16 patients of control group (88.9%), and the healing time was (24.0 ± 3.7) weeks. There was no significant difference in healing rate and healing time between 2 groups (χ2=2.346, P=0.126; t=1.990, P=0.055). The Harris score of navigation group (87.1±3.7) was significantly higher than that of control group (79.3±4.7) at last follow-up (t= -5.689, P=0.000). Conclusion Cannulated screw fixation assisted by robot navigation is a good method to treat femoral neck fractures, which has the advantages of more accurate positioning, better hip function recovery, less surgical trauma, and shorter X-ray exposure time.