Design And Clinical Application Of Lower Limb Length Measuring Instrument In Total Hip Arthroplasty

Objective: As development of of medical technology and clinical level,total hip arthroplasty has become an important means for the treatment of femoral head necrosis,femoral neck fractures,hip dysplasia and other hip diseases.The traditional total hip arthroplasty has a relatively long length of surgical incision,long operation time in surgery and the relatively slow recovery in postoperative.However,as the emergence of new prosthesis mat erials and new technologies,as well as the continuous development of hip arthroplasty,minimally invasive techniques for hip arthroplasty have been born.Minimally invasive is an new technology to gain better operation in surgery to achieve satisfactory surgical outcome and make a little damage about human body.The advantage of operation is the relatively short operation of incision,less destruction of muscle and soft tissue,and quick recovery by exercise.Minimally invasive technology is widely used in clinical application,and the degree of acceptance and satisfaction of patients is relatively high.Meanwhile,it is also widely recognized by doctors.Surgery early and late complications of total hip arthroplasty include death,hematoma,heterotopic ossification,nerve vascular injury,leg length discrepancy,fracture around the prosthesis prosthesis dislocation or subluxation,infection,lower limb deep vein thrombosis and pulmonary embolism,prosthetic aseptic loosening,bone dissolution,etc.The incidence of leg length discrepancy after hip replacement is very high,and its complications seriously affect the patient’s satisfaction after the operation.The complications of leg length discrepancy after operation are very important for doctors and patients.Before performing the total hip arthroplasty,the pelvic pelvis should be performed before operation.According to imaging measurement we measure leg length.then the templates were used to determine the better type of Prosthesis and the potential correct sizes,and provided finally operation plan and the alternative options to prevent various accidents in the operation and after the operation.This method can reduce the incidence of total hip arthroplasty,like leg length discrepancy.There may be some errors between the actual operation and the design of the template before the operation.At present,there is no measurement methods can accurately measure intraoperative and reduce the occurrence of leg length discrepancy after hip arthroplasty.So we describe a simple,safe,delicate and intraoperative device which establishes a fixed reference point in the tip of greater trochanter and measures the distance of the greater trochanter and the rotation center of hip joint.According to the data measured by the standard preoperative pelvic radiograph and the device measuring results in opertion,Using the device into THA to restore the femoral offset and minimize limb-length inequality.Methods: From April 2016 to April 2017,40 consecutive patients undergoing unilateral total hip arthroplasty were selected from the Affiliated Hospital of Southwest Medical University.The patients were randomly divided into two groups,the experimental group(20 cases)and the control group(20 cases).The experimental group used the new measuring device,while the control group used the traditional method.There was no significant difference in age,gender,pathogeny and disease duration between 2 groups.According to the standard pelvis plain film,he absolute value of the difference between the bilateral offset,the absolute value of the difference between the bilateral femoral head centre to the tip of the greater trochanter on a line perpendicular to the anatomical axis of the femur and the absolute value of the distance difference between the line connecting both tear drops and the top of the minor trochanter are be calculated.Results Comparison of the absolute value of the difference between the bilateral offset,the absolute value of the difference between the bilateral femoral head centre to the tip of the greater trochanter on a line perpendicular to the anatomical axis of the femur,and the absolute value of the distance difference between the line connecting both tear drops and the top of the minor trochanter between the experimental group and the control group,experimental group were significantly shorter than those in control group(P<0.05).Conclusion The Intraoperative methods by using the device is useful with most THA approach,the device is helpful to restore the rotation center of hip joint and minimize limb-length inequality.