| Objective:With the rapid increasing of the social elderly population ,the incidence of intertrochanteric hip fracture has becomes one of the most common orthopedics injury in the hospital ,is on the rise . In 1960, Horowitz reported that the morality follwing skeletal traction is 34.7%,while following surgery is only 17.5%.Reliable internal fixation and early mobilization were expected to be standard management.At present, operative treatment is the routine procedure for intertrochanteric hip fractures. For the majority of intertrochanteric hip fractures, the widely preferred treatment method of choice is interal fixation with the dynamic hip screw(DHS) or Gamma nails.However, the elderly patients with a host of systemic diseases can't endure regional or general anaesthesia and prolonged operating.As an alternative treatment option for these elderly ,high-risk patients,we design this kind of method which has so many advantages as simple manipulation,almost atraumatic, applied under local anaesthesia. The purpose of this study is to evaluate biomechanical performance and clinical result of the combination of external fixator and cannulated compression screws via biomechanical test on embalmed femurs of human cadavers and clinical application,so as to provide experiment and clinical data for safe clinical practice.Methods: 1 The biomechanical test of the combination of external fixator and cannulated ompression screws versus DHS 20 matched pairs of embalmed femur of the aged donaters which have similar bone mineral density scanned by DEXA were select.These specimens are divided into two groups randomly,group A and B,10 pairs in each group. According to AO classification, the fracture model was created through the intertrochanteric ridge by hand-saw.The right femur of each pair was designated as experimental group (fixed with the combination of cannulated external fixator and compression screws), the left served as control group (fixed with DHS ) . The femoral shafts were oseiotomized 30cm distal to the lesser trochanter removing the distal condyles and potted in metal holder using polymethacrylate at 25-degree adduction in the coronal plane and neutral in the sagittal plane to simulate one-legged stance. 10 paired femur in group A were used to vertical loading test. The specimens were placed on the biomechanical test machine. Vertical loading onto the femoral head is continual at a interval of 100N with the speed of 5N/S .The vertical displacement of the femoral head were record when loading from 100N to 700N.Then in the ultimate loading test,the peak loading was record when the specimens were loaded to failure. 10 paired femur in group B were used to torsional test .The specimen was fixed on the torsional testing machine .The femoral head was static ,the distal femoral shaft was turned in a clockwise direction (for left femur) or in anticlockwise (for right femur) with the speed of 6°/min.The torsional angulus was record when turning from 2 to 10Nm at a interval of 2Nm torque value.2 The clinical application of the two methods: Between March 2005 and December 2006,24 elderly patients above 60 years of age with a intertrochanteric fracture were managed with the combination of external fixator and cannulated compression screws or DHS randomly.There were 12 cases in both experimental group and control group.All the patients were followed up.Both groups were comparable in terms of the duration of surgery ,the amount of blood loss, the length of hospital stay and mean Harris scores at six months.3 The all data were denoted as mean±standard deviation and satistically analyzed by the SAS V6.12 software.The statistical significance was set at P<0.05.Result: 1 The results of biomechanical test In the vertical loading test,when loading to 700N,the vertical displacement of the femoral head is 3.305±0.133mm in experimental group and 2.205±0.069mm in control group. In the ultimate loading test,the peak loading is 1781.273±82.897N in experimental group and 2094.047±102.137N in control group. In the torsional test,when turning to 10Nm,torsional angulus is 7.874±0.284°in experimental group and 16.187±0.469°in control group. There is significant difference(P<0.05).2 The results of clinical application The average intraoperative time was 37.08±8.65min in the experimental group and 72.08±14.37 min in control group.The average blood loss was 23.33±7.49ml±and 320. 83±55.08 ml in control group. The number of units blood transfused postoperatively is none in experimental group and 1.23 units in control group.The average hospitalization time is 9.67±1.67 days in experimental group and 17.50±3.21days in control group.There were 3 superficial pin-track infections occoured in experimental group. These infections were settled with oral antibiotics and pin site care. No deep infection or osteomyelitis was found.There were 3 varus angulation in experimental group and none in control group.Conclusion: Our biomechanical data indicate that the combination of cannulated external fixator and compression screws provide adequate anti-bending stiffness stability and exellent anti-torsion biomechanical properties. Our clinical data indicate that the method has so many advantages such as simple operating manipulation ,minimal invasion,negligible blood loss, early ambulation ,a short hospital stay and removal as an outpatient procedure.It is an alternative treatmen option for high-risk geriatric patients with intertrochanteric hip fracture. |
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