Development And Biomechanical Study Of Tension Band Anchor

Background At present,for closed fractures,internal malleolus fractures,for example,the conventional practice is to perform surgery under general anesthesia and take a posterior incision in the medial malleolus.Expose the fracture end,remove joint cavity blood and bone fragments,temporarily fix the largest fracture block with cloth clamps after anatomical reduction,drill two Kirschner wire diameters of 1.0mm from the tip of the medial condyle,depth 6-7cm.A bone hole was drilled at a radius of 5-6 cm from the fracture.The 1.0 mm wire was introduced into the bone hole and crossed at the surface of the fracture line.The Kirschner wires were tied around the two Kirschner wires.After cross-fixation,the bilateral cortical bone of the tibia needs to be drilled for cross-fixation of the tension band,and the bilateral cortical bone is drilled.This not only increases the wound but also prolongs the recovery time of the patient.Or screw a 3.5mm diameter bone screw or cancellous bone screw into the humerus at a distance of 5-6cm from the fracture,perpendicular to the medial side of the tibia,or tilt it slightly upwards from 0° to 15°,and bypass the screw with 1.0mm wire.,with the screw cap pressed between the bone surface and the screw cap,if the use of ordinary screws unilateral cortical fixation after winding the tension band across the wire will cause the screw cap and bone surface does not fit,the screw is easy to loose,while the nut convex Excessively high bone surface level causes skin irritation to some degree causing discomfort and affecting recovery.Many orthopedic surgeons and materials specialists have solved the above problems in terms of surgical approaches and materials,and their results have been unsatisfactory.Objective In order to effectively solve the problems of bilateral cortical bone drilling or common screw unilateral cortical bone fixation in the existing tension band steel wire system(long operation time,prolonged recovery time of the patient,skin irritation,unstable screw wire,etc.),Orthopedic tension band anchors were designed and related biomechanical and clinical installation tools were designed.Method Designed an orthopaedic tension band anchor that can effectively solve a series of problems in the existing tension band steel wire system,and conduct biomechanical testing and related tool development.This study consists of three parts:(1)The design of orthopedic tension band anchor bolts.On the basis of reviewing the integrated literature,according to the various problems it reflects,a medical problem that can effectively solve a series of problems in the existing tension band steel wire system is designed.Titanium alloy(?-type titanium alloy)tension band anchors,expounding its material mechanics,design features and performance;(b)biomechanical study of orthopedic tension band anchors.The pork leg specimens were used as the experimental subjects.The 70 pig leg specimens were randomly divided into 7 groups: A,B,C,D,E,F,and G groups.The A and B groups were ordinary screw unilateral cortical fixation groups: Cut the epidermis on the pieces,separate the soft tissue such as muscles,expose the bones,insert a single cortical screw(outside diameter 3.5mm,length 25mm)into the vertical bone surface,and subcutaneously through a 1.0mm steel wire 6cm below the screw Wear out and tie.Group A measures the maximum pullout force,and Group B measures the vertical shear force at a displacement of 2mm.C,D,E,F,and G groups are tension band anchor groups: cut the epidermis on the test piece,separate the soft tissue such as muscle,expose the bone,and insert a tension band anchor bolt(outer diameter 3.5mm)into the vertical bone surface.Length 25mm),Tensioner with anchor bolts complete,using a wire guide through the 1.0mm wire under the skin,and piercing 6cm from the screw,take out the wire guide,the wire is inserted into the tension band anchor nut track,with Wire bundler strapping.Group C measures the maximum pullout force,Group D measures the vertical shear force at a displacement of 2mm,Group E measures the shear force of a displacement of 2mm when the wire is tilted 5° to the outside,and Group F measures a displacement of 2mm when the wire is tilted to the outside by 10°.Shear force,Group G measured 2 mm of shear force when the wire was tilted 15° to the outside.Calculate the time of operation preparation for groups A,B,C,and D.And in the measurement of shear force statistics whether the wire offset and slip.(3)Development of related tools for orthopedic tension band anchor bolts.According to the actual need of surgery,a set of installation tools for surgery was designed.Result The data obtained from the biomechanical test of tension band anchor bolts were statistically analyzed using SPSS 21.0 software.For the A and C,B and D,D and E,D and F,D and G groups of mechanical data using two-sample mean independent t test.For the time series of A+B and C+D groups,two-sample mean independent t test was used.The chi-square test was used for the wire slip.p<0.05 was considered statistically significant.Tension band anchor bolts meet the common screw standards for biomechanics such as pull-out and vertical shear.However,there was a statistically significant difference(p<0.05)in the time of operation preparation and the presence or absence of wire slippage.Conclusion The orthopaedic tension band anchor bolt is an improved screw structure and has a large clinical application value:(1)It has no difference with ordinary screws in all aspects of biomechanics,and its mechanics is within the range of 0-15° outward tilt of the steel wire.There is no significant change in strength,which can guarantee its mechanical stability to meet orthopedic surgery.(2)The application of the accessory tension band anchor and removal tool has shortened the operation time and made the operation more convenient.(3)The steel wire can be rotated around the nut track,which is conducive to adjusting the pulling direction of the wire,so that the force is more even and more stable.The steel wire can make the steel wire more stable in the track of the nut,and it is less prone to offset slip,and at the same time reduces the height of the nut.Effectively reduce the incidence of skin irritation,is conducive to the recovery of patients after surgery,more suitable for clinical needs.