This paper presents a unit free-form deformation (FFD) method applied to rapid three-dimensioanl (3D) bone reconstruction, which was based on traditional FFD. With the femur as an example, we reconstructed a 3D model of femur from two X-ray images and a standardized model by taking advantage of unit FFD algorithm. The X-ray images and its parameters were taken by C-arm device. Those parameters and X-ray contour are contributed to 3D reconstruction. The out contours of X-ray image and standard model were connected by point matching algorithm. The unit-FFD lattice was built to reconstruct standard model and finally made the contour of X-ray image and standard model exactly the same. Experiments on shape accuracy, robustness and time consuming, carried out by 35 specimen from cadaver, showed that mean error of shape (0. 52 mm) and mean construction time (112 s) were lower than those using traditional method (0.7-2.6 mm, 8-20 min). The method proposed in this paper shows a good prospect in clinical application and related research.
Algorithms ; Femur ; anatomy & histology ; diagnostic imaging ; Humans ; Imaging, Three-Dimensional ; Models, Anatomic ; Radiography

BACKGROUNDFor a child with osteosarcoma, prediction of the limb length discrepancy at maturity is important when planning for limb salvage surgery. The purpose of this study was to provide a reliable prediction method.

METHODSA retrospective review of Chinese children receiving chemotherapy for osteosarcoma before skeletal maturity was conducted. Standing full-length radiographs of the lower extremity were used for length measurements. Length-for-age curves were constructed using the LMS method. The lower limb multiplier for a specific age and gender was calculated using the formula M = Lm/L, where M was the gender- and age-specific multiplier, Lmwas the bone length at maturity, and L was the age-specific bone length. Prematurity and postmaturity radiographs were used to assess the accuracy of the prediction methods.

RESULTSA total of 513 radiographs of 131 boys and 314 radiographs of 86 girls were used to calculate the coefficients of the multiplier. The multipliers of 8-, 9-, 10-, 11-, 12-, 13-, 14-, 15-, 16-, 17-, and 18-year-old boys after chemotherapy for osteosarcoma were 1.394, 1.306, 1.231, 1.170, 1.119, 1.071, 1.032, 1.010, 1.004, 1.001, and 1.000, respectively; while for girls at the same ages, the multipliers were 1.311, 1.221, 1.146, 1.092, 1.049, 1.021, 1.006, 1.001, 1.000, 1.000, and 1.000, respectively. Prematurity and postmaturity femoral and tibial lengths of 21 patients were used to assess the prediction accuracy. The mean prediction error was 0 cm, 0.8 cm, and 1.6 cm for the multiplier method using our coefficients, Paley's coefficients, and Anderson's method, respectively.

CONCLUSIONSOur coefficients for the multiplier method are reliable in predicting lower limb length growth of Chinese children with osteosarcoma.

Adolescent ; Body Height ; physiology ; Bone Neoplasms ; surgery ; Child ; Female ; Femur ; anatomy & histology ; Humans ; Limb Salvage ; Lower Extremity ; anatomy & histology ; Male ; Models, Theoretical ; Osteosarcoma ; surgery ; Radiography ; Retrospective Studies ; Tibia ; anatomy & histology

OBJECTIVE: To evaluate the association between alpha angle and herniation pit on MRI in asymptomatic hip joints and their associations with demographic variables. MATERIALS AND METHODS: Hip MRI of 185 asymptomatic hip joints of 105 adults (age 18 to 80 years) from September 2011 through December 2012 were retrospectively studied. Alpha angles were measured on oblique axial MR images by 2 observers. Herniation pit was determined by 1 observer. Size measures, prevalence, and statistical analyses were conducted regarding its association with age, gender, laterality (right or left hip). Intra- and inter-observer agreements were determined by intra-class correlation coefficient. RESULTS: The prevalence of herniation pit in asymptomatic hips was 21.6%. The range of alpha angle was 27.6-65.0 degrees. Seventeen and 16 out of 185 (9.1% and 8.6%) hip joints showed alpha angle of ≥ 55 degrees in first and second measurement sessions, respectively. There was no association between alpha angle ≥ 55 and presence of herniation pit. There was no association between alpha angle ≥ 55 and the size of herniation pit. Inter-observer agreement of alpha angle was 0.485 between first measurements of first vs. second observer, respectively. Intra-observer agreement of alpha angle was 0.654, respectively. Forty (21.6%) of 185 hip joints (35 of 105 patients, 33.3%) had herniation pit, with no difference according to age, gender, or laterality of hip joint. CONCLUSION: There is no association between alpha angle ≥ 55 degrees and presence of herniation pit or demographic variables.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Asymptomatic Diseases ; Female ; Femur Neck/anatomy & histology/radiography ; Hip Joint/anatomy & histology/*radiography ; Humans ; *Magnetic Resonance Imaging ; Male ; Middle Aged ; Prevalence ; Retrospective Studies ; Young Adult

The purpose of this study is to design an Anatomical Contact Porous Coated Total Hip Prosthesis(ACP) which can transmit stress to the bone more physiologically and which can also eliminate the shortcomings of the currently available total hip prosthesis as much as possible. In the designing process, we have utilized computed axial tomography(CAT) and computer aid design (CAD). To obtain the shape of the femoral canal nondestructively, computed axial tomography data was obtained from fourteen male and fourteen female cadaver femurs and from twenty male and twenty female patients. To create the medullary canal in the computer, the actual dimension of each CAT-scan image was traced and digitized. For each femur a close-fit prototype of the stem was made with polyester and this was inserted into the corresponding femur in usual surgical manner. To test the accuracy of the fit of the prototype in the canal, an image of the cross-section of the canal with the polyester stem was obtained by CAT-scan in the same way that the original CAT-scan of the canal of the femur was done. We then had our computer display fit ratio between the prototype and the canal. We made sure all of the prototypes fit in the canal anatomically, especially around the defined regions (proximal medial and distal lateral regions). Further improvement was made on the fit of the stem in the canal by optimized computer programming. From studies on the shape and the size of the femoral canals of the sixty-eight femurs, eight sizes of ACP femoral stems were designed for each side. Also, on the basis of the anthropometric measurement of the acetabuli in twenty-eight cadaver hips and in the hips of forty patients with femoral neck fracture, different sizes of ACP hemispheric acetabular components were designed, ranging from 40 and 70 millimeters with 2 millimeter increments.
Acetabulum/anatomy and histology/radiography ; *Computer Simulation ; *Equipment Design ; Female ; Femur/anatomy and histology/radiography ; *Hip Prosthesis ; Human ; Male ; *Models, Anatomic ; *Models, Biological ; Polyethylenes ; Support, Non-U.S. Gov't ; Surface Properties ; Tomography, X-Ray Computed

In current study of femoral head necrosis and femoral neck fractures, more attentions has been paid to relationship between the femoral head trabecular bone within the spatial structure and its biomechanics. In this connection, PMMA (polymethyl methacrylate), special square iron, dental base acrylic resin liquid and powder were used to embed and fix human dry femur. Then, M618 Lie Axle Rectangle Desk Plane Grinding Machine was applied to grind the femur specimen, and then air blower clean, two-dimensional cross section image was obtained by using scanner. With Mimics software reconstruction, a three-dimensional model of spatial structure of trabecular bone was obtained, and the trabecular bone three-dimensional parameters were calculated. The authors obtained clear three-dimensional model of trabecular bone, reconstructed the real anatomic morphology of proximal femur. This is a good method to research into the interior structure of femur and to provide the foundation for the three-dimensional finite element analysis.
Biomechanical Phenomena ; Compressive Strength ; Computer Simulation ; Femur ; anatomy & histology ; diagnostic imaging ; physiology ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; methods ; Models, Anatomic ; Radiography

PURPOSE: The object of this study was to evaluate entrance angle effects on femoral tunnel length and cartilage damage during anteromedial portal drilling using three-dimensional computer simulation. MATERIALS AND METHODS: Data was obtained from an anatomic study performed using 16 cadaveric knees. The anterior cruciate ligament femoral insertion was dissected and the knees were scanned by computer tomography. Tunnels with different of three-dimensional entrance angles were identified using a computer simulation. The effects of different entrance angles on the femoral tunnel length and medial femoral cartilage damage were evaluated. Specifically, tunnel length and distance from the medial femoral condyle to a virtual cylinder of the femoral tunnel were measured. RESULTS: In tunnels drilled at a coronal angle of 45degrees, an axial angle of 45degrees, and a sagittal angle of 45degrees, the mean femoral tunnel length was 39.5+/-3.7 mm and the distance between the virtual cylinder of the femoral tunnel and the medial femoral condyle was 9.4+/-2.6 mm. The tunnel length at a coronal angle of 30degrees, an axial angle of 60degrees, and a sagittal angle of 45degrees, was 34.0+/-2.9 mm and the distance between the virtual cylinder of the tunnel and the medial femoral condyle was 0.7+/-1.3 mm, which was significantly shorter than the standard angle (p<0.001). CONCLUSION: Extremely low and high entrance angles in both of axial plane and coronal plane produced inappropriate tunnel angles, lengths and higher incidence of cartilage damage. We recommend that angles in proximity to standard angles be chosen during femoral tunnel drilling through the anteromedial portal.
Aged ; Anterior Cruciate Ligament/*surgery ; Anterior Cruciate Ligament Reconstruction/instrumentation/*methods ; Cadaver ; Computer Simulation ; Female ; Femur/anatomy & histology/*surgery ; Humans ; Imaging, Three-Dimensional ; Knee Joint/radiography/*surgery ; Male ; Middle Aged ; Osteotomy/*methods ; Outcome and Process Assessment (Health Care) ; Patient Positioning ; Surgical Instruments ; Tomography, X-Ray Computed