| Objective To explore the outcome and advantage of the lateral locking plate and medial K-wires for simple distal humerus fractures osteosynthesis.Methods From March 2006 to March 2012, there were 47 patients,29 males and 18 females, the mean age at the time of injury was 36.5 years(range, 18～53). The time between injury and operation was 8h to 7 days. According to AO/ASIF classification,23 belonged to supracondylar fracture(type A),24 to intercondylar fracture(type C1). The cause of fractures included 21 traffic accidents,5 cases of occupational,8 cases of falling down.3 cases involved open fracture and 2 involved ulnar nerve palsy.22 cases were treated with dual plating, and 25 cases with lateral locking plate and medial K-wires. The observational index included operation time, the periosteal area stripped during operation, fracture healing time, elbow joint function after surgery. All patients were treated by intravenous infusion of antibiotics for 1～3days postoperatively. Early ice compress played an important role to relieve the swelling of the limb. Joint exercises was performed passively 3-5 times per day by doctor immediately after operation in the first postoperative week, range of motion of the elbow was 0°～15° of extension and 125°～135° of flexion. The frequency of joint passive exercises would be 8-10 times in the second postoperative week. The patients were encouraged to perform active motion of the shoulders and elbows in the third postoperative week, two groups a day and a group of 10 times. A functional brace with angular limitation was applied to prevent osteosynthesis loosening when they were at rest. Biomechanical studySix cadaveric humeri were used in the laboratory experiments, with 3 left and 3 right. X-rays of the humeri were performed to excluded any pathology or previously treated fractures. All bones were stripped of soft tissue. Each specimen would be performed two kind of fracture and two kinds of osteosynthesis.Material Testing Machine (DaoJin AGS-X10KN) was used to perform the mechanical testing. All bones were loaded to force which can produce 10mm compress on the distal humerus fracture, and the load was recorded. The displacement at the fractures site and the parameter load were utilized as the main outcome. The first, the load inductor was put at the 5mm proximal to the distal elbow joint surface. Second, the inductor move down at a static 3mm/minute, and when the force was 15N, the inductor was stopped. Then the force was made for 0, and the distance was 0. The third, the inductor move down at a static 10mm/minute, the force which produced a 10mm distance on the distal humerus fragment were determined from all tests.Statistical analysis of the date was performed by the Spss 13.0 version statistic package. U-test was used to compare double plate osteosynthesis and lateral locking plate and medial K-wires osteosynthesis group’s parameter values. Spearman rank coefficients of correlation were calculated to find the relations among the parameters. P value was set at P<0.05. Data were presented as mean± standard deviation.Results All the patients were followed no less than 12 months, all patients have obtained complete bone-union within 12～18 weeks (average 13.5 weeks). The mean value for operation time in dual plates group was 139.09±17.63minutes, and the lateral plate and medial K-wires was 112.60±13.70minutes, t=4.619, p=0.001, P<0.05. There is great difference between the two group in operation time, which means lateral plate and medial K-wires group is easier to perform the operation. The periosteal area stripping during operation, was 32.90±2.24cm2 in the dual plates group, and 28.48±2.19cm2, in the lateral plate and medial K-wires.1=3.434, p=0.001, P＜0.05, There is great difference between the two group in the periosteal area stripping during operation, which means soft tissue and periosteal can be less injury in the lateral plate and medial K-wires group. The fracture healing time, was 16.27±2.58 weeks, in the dual plates group, and 13.16±1.10weeks, in the lateral plate and medial K-wires. t=5.241, P=0.001, P<0.05, There is great difference between the two group in the fracture healing time, which means the osteosynthesis of the fractures is stable enough and there are less injury to the blood supply to the fragment of the bone. The elbow joint function after surgery, according the Cassebaum performance index system, there were 14 excellent and 7 good cases in the dual plate group, with 16 excellent and 7 good cases in the lateral plate and medial K-wires group. According to the Mann-Whitney test, t=0.950, p>0.05, there was no difference in elbow joint function between two groups after surgery. There is nervous irritability after dual plating operation in two cases, and the symptom decreased with time and resolved in six months with in the follow-up evaluation.Biomechanical study:In the biomechanical trail, the two osteosynthesis were evaluated in the extension position and flexion position. The first, the osteotomy of the distal humerus was the type A fracture according to AO/ASIF. In the extension test, the intensity of the dual plates group was 327.47±14.80, and 303.80±11.60N in lateral locking plate and medial K-wires group, (p>0.05), there was no difference in the two groups. In the flexion test, the intensity of the dual plates group was 311.56±18.92N, and 277.23±17.45N in lateral locking plate and medial K-wires group, p<0.05, there was significant difference in the two groups.The second, the osteotomy of the distal humerus was the type C1 fracture according to AO/ASIF. In the extension test, the intensity of the dual plates group was 267.18±15.22N, and 241.5±12.08N in lateral locking plate and medial K-wires group, p<0.05, there was significant difference in the two groups. In the flexion test, the intensity of the dual plates group was 213.19±10.34N, and 182.42±14.04N in lateral locking plate and medial K-wires group, p<0.05, there was significant difference in the two groups.Conclusion According to the biomechanical study, there was only 15% of the difference in the mean values of the load between the two groups specimens. It can get excellent outcome by external functional brace after operation. This study made a theoretical support to offer a promising alternative for simple distal humerus fracture treatment. This clinical study indicates that lateral locking plate and medial K-wires can provide sufficient immediate postoperative stability to allow early physiotherapy, especially in type C1 intercondylar fracture and type A supracondylar fracture according to AO/ASIF classification. The fracture should not be comminuted. This technique is a clinically effective surgical method to protect ulnar nerve and easy to perform. Excellent or good results can be achieved in the most majority patients. |
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