Application Of Virtual Reality Technique In The Hip Resurfacing

Advanced stage of avascular necrosis of the femoral head,congenital hip dysplasia,slipped femoral epiphysis,and ankylosing spondylitis will induce severe hip pain and dysfunction, for such advanced hip joint disease,the better treatment is carried out total hip arthroplasty.For a long life expectancy,better bone conditions, more activity volume,in the future faced by overhaulinged,the patient will be encouraged to select the hip resurfacing arthroplasty,such as following features:1.HRA can be more precise reconstruction of the proximal femoral anatomy, so that the stress distribution more in line with physiological condition with less stress shield;2.HRA to maximize the preservation of bone mass and physical structure, which made hip activity of the restored closer to normal levels;3.To retain more bone, increase hip stability;4.Not undermine the bone marrow cavity,facilitate the renovation of secondary,non-debris-induced osteolysis,aseptic loosening of prosthesis didn't occur.Several authors have reported report of the relevant clinical data rate of 94.4-99.7% excellent.However,hip resurfacing arthroplasty complications can not be ignored,common complications include femoral neck fractures,femoral neck narrow, serum cobalt chromium metal ions increasement,lower limb shortening limp,groin area pain and formation of lumps.According to the relevant research data shows that avascular necrosis of the femoral head in total hip arthroplasty in the proportion of patients was 5% -12%. Appropriate patients,correctly placement of prosthesis,rationality use of bone cement,intraoperative navigation technique and preoperative simulation of surgery can significantly reduce the incidence of postoperative complications or reduce the complications of hazards.Current the best indications of hip resurfacing arthroplasty are:good reserved bone,the femoral head diameter and neck diameter ratio greater than 1.2,lower limb shorten the length less than 1cm,younger than 55 years of age, body weight less than 82 kilograms and non-infection hip disease.Traditional Preoperative ready for HRA included X-ray of pelvis and CT-scan,mainly assessment of bone destruction,head and neck ratio,selection the size of the prosthesis,and a preliminary assessment of femoral head collapse from the two-dimensional.But the two-dimensional structure is difficult to complete reflect the true information, especially the scope of the femoral head collapse,area of cystic and hardening with quantitative and postoperative bone area after osteotomy.application of non-images, computer-guided. technique can shorten the learning curve for beginners, intraoperative feedback in a timely manner,so that femoral prosthesis placed in the best position.But also there are some disadvantages:1.Operative time was relatively long;2.Infrared reference frame should be avoided collision and move,otherwise need to re-register.3.Anatomical landmark point must be accurate,otherwise affect the image matching accuracy.Currently,hospital's introduction of non-imaging navigation system is also less present in our country with clinical exploratory stage,and lack of a large sample of clinical application of the system,it is necessary to conduct related technical and theoretical research, acceptance of this new surgical concept.With the rapid development of computer technology,virtual reality technique(virtual reality VR) in medicine is playing an important role.Clinically,in order to avoid direct surgical surgery strategies generating enormous risk,and currently the best solution is to establish a virtual simulation system. Three-dimensional virtual simulation system is based on three-dimensional model of medicine to carry out Surgical planning and virtual operations.To carry out research in this area in accurate positioning during operation,shorter operative time and improve the quality of surgery to bring about a series of technological change.At present,the majority of the medical simulation study focused on making use of patient medical image data (CT/MRI images) or people (Virtual Human VH) database to construct the modeling of human tissues and organs,the application of Materialise's interactive medical image control system(mimics) or 3dsmax software systems in surgical simulation,surgical plan,operation instruction,skills training,postoperative rehabilitation and so on.Currently virtual surgery simulation system is mainly involved in maxillofacial surgery,orthopedic surgery,neurological surgery,virtual endoscopy,etc.medical image data is entered into the correlated system,the original image will be diverted into more facilitated computer format,with image noise reduction,improve signal to noise ratio and the elimination of image artifacts,by extracting a region of interest(ROI),spliting surgical site and modality image registration or fusion,visualization of three-dimensional structure has been an intuitive show.With interactive procedures,the visualization of three-dimensional model can be conducted a series of interactive operations (rotation,zoom,pan,cut, measure, mix,and the virtual implant surgical placement,etc.to achieve the simulation).Visualization of virtual surgery is currently the main application of spinal fixation system for positioning,complex fractures or selection of individual internal fixation,total hip replacement and total knee osteotomy. Research on the objective assessment of the hip and design personalized virtual surgery has been reported rarely reported at home and abroad.In this research,we make use of Mimics software in the advantages of digital simulation and three-dimensional modeling to reconstruct 3D model of pelvis by initial data from the Philips Brilliance 64-slice spiral CT scans,and appraisal three-dimensional pelvic reconstruction exactly,which included femoral head cystic area,hardened area,and the acetabular bone;The 3D model will be input into Geomagic studo 8.0 and 3dsmax software to carry out visible virtual operation,to implement clear neck center position,accurate osteotomy plane,suitable prosthesis size and optimization component localization,we can achieve the greatest degree of optimization with Preoperative visible simulation surgery. Chapter one:Reconstruction of avascular necrosis of the femoral head 3D model based on CT imageObjective:1.To investigate an easier and more precise method of reconstruction of the hip 3D model based on CT Images;2.To assess the diseased tissue of hip.Methods:In advantage with the 0.625 mm isotropous imaging resolution scan Technique of Philips/Brilliance 64 rows spiral CT,we got 286 layers of2-Dimensional CT pictures of hip atlas and axis.Mimics 10.01 read these original Dicom' format pictures in and extracted each deck contour line automatically after defined bone tissue threshold.Every layer of picture would be processed by parting edge of it,editing it selectively,repairing the hole of it and removing the redundant data from it,namely establishment 3D model of acetabulum,proximal femur,femoral neck,and femoral head lesions.All rebuilded tissue will be Input into Geomagic studo 8.0 software and equipped with quasi-smooth handling as STL format.Results:The three-dimensional reconstruction of the hip (including the diseased tissue) and the preoperative imaging data, intraoperative findings fit together well.It has lifelike appearance,can be arbitrarily rotated or zoomed and displayed with colorful,transparent or arbitrary combination of image.Therefore,it has a better visual effect.Through this model,we can observe the inner structure relation of each component from any plane of different cross-section.The internal structure can be split,separated diseased tissue(cystic change and hardening belt).wo can objectively assess the diseased tissue of hip.STL format file put into Geomagic studo and 3dsmax software system can implemented virtual simulation surgery.Conclusion:Mimics software,according to the original data Dicom from CT scan obtained an accurate reconstruction of 3D model of hip joints in patients,wo can calculate diseased tissue volume,providing objective evaluation hip bone. Chapter two:Application of visible simulation surgery in the hip resurfacingObjective:1.To select the appropriate prosthesis type(femoral and acetabular prostheses);2.Exactly Centralization neck of femur,precise osteotomy and component localization,to provide preoperative digital Evaluation of hip and improve of surgical technique.Methods:The prosthesis size measurements:Three-dimensional reconstruction model of hip was input into the 3dsmax software as STL format.the diameter of Femoral neck of maximum and minimum were,44mm,40mm,respectively (measurement process in geomagic8.0),so femoral prosthesis size was 44mm.â… .Centralization neck of femur:As the femoral neck was not a standard cylindrical or oval cylindrical, the center of femoral neck bone was not Consistent with femoral head,in this research study a guide pin was inserted into the center of femoral neck center In parallel with the femoral head,because the apparent ipsilateral anterolateral femoral head collapse,the accumulation of large areas of cystic degeneration,and then the medial cortical bone better.to remove more of the cystic tissue and retain more the integrity of bone,so guide pin shift to the rear 3mm.â…¡.Virtual Osteotomy:(1) Along the direction of guide pin,virtual platform rasp remove approximately 6mm thick bone from the proximal femoral neck.(2)virtual barrel rasp of diameter was 44mm,the proximal femur could be polished by barrel barrel rasp to the junction of the head and neck.To observe whether there wre some notchs at the femoral neck cortex,and calculate the volume of the residual areas of cystic degeneration.(3)Virtual cone-shaped rasp the femoral made femoral head match femoral prosthesis.Results:In 3dsmax v7.0 software system,by Boolean logic operation system,simulation of process of hip resurfacing,the effect was vivid,lifelike.surgeon could implement clear neck center position,accurate osteotomy plane,suitable prosthesis size and optimization component localization.Through the virtual grinding process was displayed on the screen.Conclusion:Different virtual surgical instruments were established in the 3dsmax v7.0(virtual platform rasp,virtual barrel rasp,Vrtual cone-shaped rasp),to carry out virtual proximal femoral grinding by Boolean logic operation.Throughout the implantation process,the implant angle data was always displayed on the computer screen,the location of prosthesis was in the form of virtual real-time update the display,so surgeon are very clear of prosthesis position.In this research,visual simulation technology enables the surgeon in trying to reserve more bone mass of femoral neck,removal of cyst area in the greatest degree and optimization component localization.