Establishing A Customized Guide Plate For Osteotomy In Total Knee Arthroplasty Using Lower-extremity X-ray And Knee Computed Tomography Images

PART I Application comparison of 3D-printed osteotomy guide plates from two different designs in the model’s test-surgery of the total knee arthroplastyObjective To compare the advantages and disadvantages of 3D-printed osteotomy guide plates from two different designs in the model’s test-surgery of the total knee arthroplasty.Methods Fifteen patients who underwent the total knee arthroplasty in June 2015 in the orthopaedic department of Guizhou provincial people’s hospital were selected in this study.There were 6 male cases and 9 female cases who were 53-86 years old, average 67.8 years old.After admission,the standing long-leg lower-limb X-ray with calibrator and the thin-slice computed tomograph of the knee were completed in all 15 patients. The three dimensional models of lower extremities were built with the help of the SSM(statistical shape model) technology and 2D/3D images registration technology,then the position and angle of the osteotomy were obtained through the digitally simulated surgery.To implement the osteotomy plan above,we designed two kinds of guide plates including the osteotomy groove group(OGG) and the positioning screw group(PSG).This two different kinds of guide plates and the three dimensional shape model of the knee were 3D-printed with the polylactic acid(PLA) material.Then the test-surgery was implemented so as to compare two kinds of the guide plates.Results The osteotomy time:OGG:36.5±6.2min,PSG:27.8±4.3min;the breakage of the guide plates:OGG:8/30,the rate of breakage26.7%,PSG:0/30,rate of breakage0%;the thickness deviation of the resected bone:OGG:3.4±2.5mm,PSG:1.6±1.7mm,the smoothness of osteotomy surface in PSG was better;the time of 3Dprinting:OGG:307±28min,PSG:302±25min。The differences of the osteotomy time,rate of breakage,thickness deviation of the resected bone between the two groups had statistical significances,while the difference of the 3D-printing time was not statistically significant.Conclusion In the test-operation of 3D-printing model,compared with osteotomy groove guide plate,the application of the positioning screw guide plate has the shorter osteotomy time,the less thinkness deviation of the resected bone from the preoperative plan,the smoother osteotomy surface and lower breakage rate of the guide plates.But the difference of the 3D-print time between two kinds of the guide plate had no statistical significance.PART II The clinical study of the digital simulation technology in the prosthesis size prediction of the total knee arthroplastyObjective: To compare the digital simulation technology with conventional film template in the prosthesis size prediction of the total knee arthroplasty(TKA).Methods:Between January and June 2015,60 patients who underwent a TKA in the orthopedic department of Guizhou Provincial People’s Hospital were divided into a digital simulation group(DSG)(30 cases) and a conventional template group(CTG)(30 cases) using a random number table method.In DSG, the prosthesis sizes were predicted by digital simulation of surgery including osteotomy and placement of the prosthesis.In CTG,the comparisons between the film template and the X-ray radiographs with the same magnification were conducted to decide the prosthesis sizes.Then the accuracies of the two groups were compared.Results:For the femoral prosthesis size prediction,there were 2 cases 1#-size different from actual size and 1 case 2#-size different from actual size in DSG;and 7 cases 1#-size different from actual size and 2 case 2#-size different from actual size in CTG.The femoral prosthesis predicting accuracy were 90.0% and 70.0% in DSG and CTG respectively. For the tibial prosthesis size prediction,there were 2 cases 1#-size different from actual size in DSG;and 8 cases 1#-size different from actual size and 2 case 2#-size different from actual size in CTG.The tibial prosthesis size predicting accuracy were 93.3% and 66.7% in DSG and CTG respectively.The differences were significant statistically.Conclusion:The prediction of the prosthesis size with the digital simulation technology was accurater than with the conventional film template.This can provide the basis of advanced preoperative planning and the prosthesis preparation.PART III The comparative study of a patient specific osteotomy guide plate in total knee arthroplasty constructed with long leg lower-limb X-ray and knee computed tomograghy imagesObjective: The conventional surgery cannot ensure the accurate osteotomies which is necessary for a excellent realignment and a good prognosis after total knee arthroplasty(TKA). This study evaluated a patient specific osteotomy guide plate in TKAs which was constructed with standing long-leg lower-limb X-ray and computed tomograph images through the statistical shape model(SSM) and 2D/3D registration technique.Methods: Forty-two patients who underwent a TKA(total knee arthroplasty) from October 2014 to June 2015 in the orthopaedic department of Guizhou Provincial People’s Hospital were divided into two groups:a guide plate group(GPG, 21 cases) and a traditional surgery group(TSG, 21 cases) through the random number table method. In the GPG, a knee shape model was synthesized with calibrated standing long-leg X-ray through the SSM(statistical shape model) technology.Then the model was registrated with the knee model reconstructed from the thin layer computed tomograph.So the three dimensional model of lower extremity was established.The osteotomy guide plate was designed and 3D-printed from preoperative three dimensional measurements,plan and digitally simulated surgery. Patients in TSG were treated with the conventional surgery including intramedullary and extromedullary positioning methods. Postoperative image-examination and short-term follow-up were conducted to evaluate outcomes of two groups.Results: Operative time was 49.0 ± 10.5 min for GPG, and 62.0 ± 9.7 min in TSG. The coronal femoral angle, coronal tibial angle, posterior tibial slope, and the angle between the posterior condylar osteotomy surface and the surgical transepicondylar axis were 89.2 ± 1.7, 89.0 ± 1.1, 6.6 ± 1.4, and 0.9 ± 0.3 in GPG, and 86.7 ± 2.9, 87.6 ± 2.1, 8.9 ± 2.8, and 1.7 ± 0.8 in TSG respectively. The Hospital for Special Surgery(HSS) scores 3 months after surgery were 83.7 ± 18.4 in GPG and 71.5 ± 15.2 in TSG. Statistically significant differences were found between GPG and TSG in all measurements.Conclusion: A patient specific osteotomy guide plate in TKAs created from lower-extremity X-ray and knee CT images was feasible. The guide plate surgery can bring shorter operative times and better postoperative alignment than the traditional surgery. Application of the digital guide plate may also result in better short term prognosis.