According to Bipolar Hemiarthroplasty of the Hip (BHA), several reports indicated earlier acquisition of walking ability in direct anterior approach (DAA) than posterior approach (PA), but there is still few randomized studies comparing accuracy of stem insertion in DAA and PA. Therefore, we performed a prospective study, focusing positioning of implant. We chose 29 patients for this study, diagnosed as femoral neck fracture (Garden grade III or IV) from April 2012 to April 2013, excluding obesity patients (body mass index upper than 30kg/m2), muscular patients, osteoporotic patients (Sigh grade I or II), and tumor bearing patients. Patients were enrolled in a prospective, non-blinded study and were randomly assigned by envelope method to receive either DAA or PA. Taperloc BHA system (Zimmer) was adapted for all cases. Patient condition, operation condition and radiographic findings were investigated. On CT imaging, Canal fill was calculated Stem fill was studied at lower point of lesser trochanter that was considered to be load center. Static analysis was carried out using SPSS ver21 (IBMc). Continuous variables between the two groups were compared using a no matched bilateral Student's Purpose
Patient and Methods
We have been using 3-dimensional CAD software for preoperative planning as a desktop tool daily. In ordinary cases, proper size stems and cups can be decided without much labor but in our population, many arthritic hip cases have dysplastic condition and they often come to see us for hip replacement after severe defects were created over the acetabulum. It is often the case that has Crowe's type III, IV hips with leg length difference. For those cases preoperative planning using 3D CAD is a very powerful tool. Although we only have 2-dimensional display with our computer during preoperative planning, 3 dimensional geometries are not so difficult to be understood, because we can turn the objects with the mouse and can observer from different directions. We can also display their sections and can peep inside of the geometries. It is quite natural desire that a surgeon wishes to see the planed geometries as a 3-dimensional materials. For some complicated cases, we had prepared plastic model and observed at the theater for better understanding. When we ask for a model service, each model costs $2,500. We also have small scale desk top rapid processing tool too, however it takes 2 days to make one side of pelvis. Observation of the geometries using 3-dimensional display can be its substitute without much cost and without taking much time. The problem of using 3D display had been the special goggle to mask either eye alternatively. In the present paper, we have used a 3D display which has micro arrays of powerful prism to deriver different image for each eye without using any goggle. After preoperative planning, 2 images were prepared for right eye and left eye giving 2-3 degree's parallax. These images were encoded into a special AVI file for 3-dimensional display. To keep fingers away from the device, several scenes were selected and 3-dimensional slide show was endlessly shown during the surgery. Cup geometries with screws had been prepared and cup position with screws direction were very useful. The edge of acetabulum and cup edge are well compared then could obtain a better cup alignment. Screws are said to be safe if they were inserted in upper posterior quadrant. However so long as the cluster cup was used, when the cup was given 30 degrees anterior rotation, 25 mm screw was still acceptable using CAT angiography.Method
Result
