| Total knee arthroplasty(TKA)is an effective method of pain relief and functional recovery in patients with knee joint disease.Numerous studies have demonstrated that the implant survivorship of TKA patients is greater than 90% after 10 years or more.However,recent studies concerning patient satisfaction have shown that as many as 15-30% of patients remain “unsatisfied” after TKA.The restoration and accuracy of femoral component rotational and axial alignment is considered to be one of the most influential factors of implant failure and clinical outcomes.Traditional total knee replacement surgery by the X-ray examination in the preoperative and intraoperative mechanical guide intramedullary extramedullary positioning osteotomy,the surgeon,with the naked eye,feel and experience to locate anatomic landmarks,axial alignment of the lower limb and the rotation axis of the prosthesis,and then manually crossed osteotomy and prosthesis placement and soft tissue balance.this completed by the naked eye observation of limb and the prosthesis alignment on the line a lot of subjectivity a direct impact on the reliability and accuracy of the operation of the positioning mode,and even lead to the failure of the surgery.And in the traditional surgical method by referring to the preoperative lower limb full length X to design the axial force line and in the operation rely on personal experience and sensory feelings to determine and identify the bony logo,will lead to increased subjectivity error,and the last The use of fixed angle design of the osteotomy device for knee replacement,due to ethnic and individual differences will lead to postoperative curative effect of the deviation.In recent years,with the continuous development of digital orthopedic technology and Mimics,Geomagic and other software in the application of total knee replacement surgery development,to make up for the lack of traditional surgical positioning,through preoperative digital measurement,simulated surgery and osteotomy guide design,It is possible to obtain precise axial force line of the lower limbs and the rotation force of the femoral distal prosthesis,but how to fully utilize the application of digital technology in total knee arthroplasty,especially how to accurately locate the axial alignment of the lower limb and locate the most reliable axis of rotation---surgical transepicondylar axis(STEA),to achieve individual precise osteotomy,there is still controversy.Purpose1: Using the femoral full-length computed tomography scan and three-dimensional reconstruction,The color map are used to locate the bone markers at the distal end of the femur and establish the world coordinate system.Through the world coordinate system,to establish a precise and unified three-dimensional measurement platform.2: We applied The color map to locating STEA.and the STEA guide plate made by 3D printing,total station and 3D-CT were used for verifying its accuracy.The angular relationship between the rotation axes provides a methodological basis for accurate positioning of the rotation force line for total knee arthroplasty.3: The application of centroid method to accurately locate the femoral axial force line,and the relationship between femoral valgus angle and “intraoperative femoral valgus angle”,to explore the femur into the medullary point and the relationship between the top of the femoral intercondylar notch,so this may lay methodology foundation for accurate locating the distal femoral axial force line in TKA.4,The design of personalized femoral osteotomy guide to improve the distal femoral bone and the accuracy of bone rotation.Methods26 cases of femoral specimens and the femur CT data in 80 cases was collected and three-Dimensional(3D)reconstruction in the Mimics 15.0,and were import into Geomagic Studio 2013.1: The color map was used for locating the bone markers of distal femur.2:The color map was used for locating the center of the sulcus of the medial epicondyle,the most prominent point of the lateral epicondyle and the STEA.STEA guide plate made by 3D printing,total station and 3D-CT were used for verifying its accuracy.And the distal femur CT data was collected in 80 cases,the recognition rate for the center of the sulcus of the medial epicondyle and STEA was compared by the color map and traditional methods.3:The color map was used for locating STEA、PCA、Whiteside’s line(WL),Measurement of the posterior femoral condyle angle(PCA),WL and surgical condylar axis(STEA)angle(WSTEA)were analyzed statistically.4:The application of centroid method to accurately locate the femoral axial force line,to explore the femur into the medullary point and the relationship between the top of the femoral intercondylar notch,and the relationship between femoral valgus angle and “intraoperative femoral valgus angle”,Measurement of these parameters were analyzed statistically.Results1:Mimics can accurately reconstruct the three-dimensional model of the femur,the distal femoral bone markers were accurately located by the color map.2: The center of the sulcus of the medial epicondyle and the most prominent point of the lateral epicondyle were accurately located by the color map.The two markers located by femoral condyle guide plate and total station in accordance with 3D-CT locaction in 26 cases of femoral specimens.The recognition rate of the center of the sulcus of the medial epicondyle by the color map is 96.23% and with higher accuracy and repeatability,but it was only 68.87% by traditional tomography section location.3:The distal femoral rotational force line were accurately located by the color map.PCA:3.98°±1.49°(range 0.15°-6.95°);WSTEA:86.89°± 4.09°(range 76.42°-99.27°).These two angles have greater variability.there was significant difference between left and right side in terms of PCA.4:The femoral anatomic axis were accurately located by the centroid.The femoral valgus angle:4.53°±0.74°(range2.84°-6.35°);The “intraoperative femoral valgus angle”:4.65°±0.75°(range3.10°-6.37°);there was significant difference between these angles.The distribution of entry points at the distal femurs of the sagittal axis:6.71mm±2.38mm(range0.86mm-13.59mm);The distribution of entry points at the distal femurs of the coronal axis:3.11mm±1.72mm(range0.14mm-9.19mm);These distances have greater variability.Conlusion1:The color map can accurately locate the rotating force line of distal femoral.the positioning of the rotating force line by PCL and WL may lead to the osteotomy is not accurate in TKA.The color map can accurately locate the STEA,The STEA were accurately located by the color map.and may be effectively used for preoperative planning,intraoperative rotation center location and prosthesis implantation,to obtain good postoperative knee function.2 : the femoral anatomic axis were accurately located by the Centroid.so this may lay methodology foundation for accurately and individualization locating the femoral axial alignment in TKA. |
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