Sheng-Mou Hou

A new tool for measuring cup orientation in total hip arthroplasties from plain radiographs.

Orientation of the hip cup is important in total hip arthroplasties. Orientation includes abduction (inclination) and anteversion. Anteversion can be considered as true (anatomic) and planar (radiographic) anteversion. Some measurement methods either are too complicated or are less precise. We developed a new protractor to measure cup orientation using postoperative anteroposterior radiographs centered at the hip. The new protractor measures true and planar anteversion and abduction easily and precisely. We verified its accuracy using a software simulator and simulated 45 radio- graphs of total hip arthroplasties with 15 different anteversions ranging from 15°-29° and 45 actual radiographs of total hip arthroplasties. We then measured the planar ante- version with our method and the method of Lewinnek et al. Maximal errors were 3° and 2.61°, respectively, and mean errors were 0.96° and 1.2°, respectively. The standard deviations were 0.74° with our method and 0.57° with the method of Lewinnek et al. For the real radiographs, the mean of absolute difference between the two methods was 1.34°, and the standard deviation was 1.13°. We found no difference between the two methods and no difference in our findings compared with those of Pradhan.Level of Evidence: Diagnostic study, level II.

Measurement of the acetabular cup anteversion on simulated radiographs.

Widmer (J Arthroplasty 2004;19:387) reported a protractor for measuring the anteversion of acetabular cups on radiographs but with limited precision. We intended to improve its precision by trigonometric mathematics. We measured the anteversion of the acetabular cups on 336 simulated radiographs using aforementioned 2 methods. The anteversion measured by Widmers protractor ranged from 7 degrees to 41 degrees (mean +/- SD = 28.0 degrees +/- 9.8 degrees), and our methods, 5 degrees to 51 degrees (27.7 degrees +/- 13.2 degrees). The mean +/- SD of error by Widmers protractor was 5.2 +/- 2.5 degrees, and our protractor, 0.8 degrees +/- 0.8 degrees (Student t test, P b .0001). The interobserver study showed the difference between measurements less than 2 degrees for each method. Therefore, the smaller error of our method than that of Widmer implicated a potentially precise measurement of the anteversion (level of evidence: diagnostic study, level II).

Ununited femoral neck fractures by open reduction and vascularized iliac bone graft.

Neglected femoral neck fractures are frequently complicated with nonunion and avascular necrosis of the femoral head. The treatment is especially difficult in young adults because arthroplasty is not indicated. Five cases of neglected femoral neck fractures in young patients were treated by open reduction and internal fixation with pins. The defect of the femoral neck was filled with a block of vascularized iliac bone graft. After at least two years, the fractures were healed without avascular necrosis of the femoral head. The leg-length discrepancy was corrected in all but one case. The pedicled iliac graft provided a viable bone graft, which maintained the viability of the head and hastened fracture healing.

The Metastasectomy and Timing of Pulmonary Metastases on the Outcome of Osteosarcoma Patients

Background The author intended to clarify the therapeutic effect and prognostic factors of metastasectomy and timing of pulmonary metastases in osteosarcoma patents. Methods Data was obtained retrospectively on all consecutive osteosarcoma patients from 1985 to 2005 in authors institute. Fifty-two patients with pulmonary nodules were identified, including 24 patients undergoing pulmonary metastasectomy treatment. These patients were categorized into four groups: group 1, patients with lung metastases at the initial presentation; group 2, lung metastases identified during the period of pre-operative chemotherapy; group 3, lung metastases identified during period of the post-operative chemotherapy; group 4, lung metastases identified after therapy for the primary osteosarcoma completed. Results In our study, the 2-, 3-, and 5-year overall survival rates for 52 patients were 49%, 39% and 20%. The 2-year overall survival rates were 18% for group 1, 32% for group 3, and 70% for group 4 (p < 0.001). The 5-year overall survival rate was 34% for group 4. Patients who underwent metastesectomy showed a better survival outcome as compared with the patients not undergoing metastasectomy (p = 0.003). The 2-year and 5-year overall survival rates of only one lung metastatic nodule were 62% and 50%, and for initially multiple lung metastatic nodules, 45% and 5%, respectively. In addition, the patients presented with lung metastases had a worse prognosis as compared with those without initial lung metastases (p = 0.0001). Conclusions The patients having single metastatic nodule showed a better prognosis than those with multiple lung nodules. Furthermore, those patients who underwent metastasectomy survived longer than those not undergoing metastasectomy. Patients who had late metastases after complete chemotherapy had a better prognosis; whereas those who had metastases identified at the initial presentation predicted a poor prognosis.

TNF-α increases αvβ3 integrin expression and migration in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumour with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. Tumour necrosis factor (TNF)‐α is a key cytokine involved in inflammation, immunity, cellular homeostasis and tumour progression. Integrins are the major adhesive molecules in mammalian cells and have been associated with metastasis of cancer cells. However, the effects of TNF‐α in migration and integrin expression in chondrosarcoma cells are largely unknown. In this study, we found that TNF‐α increased the migration and the expression of αvβ3 integrin in human chondrosarcoma cells. Activations of MAPK kinase (MEK), extracellular signal‐regulating kinase (ERK) and nuclear factor‐κB (NF‐κB) pathways after TNF‐α treatment were demonstrated, and TNF‐α‐induced expression of integrin and migration activity was inhibited by the specific inhibitor and mutant of MEK, ERK and NF‐κB cascades. Taken together, our results indicated that TNF‐α enhances the migration of chondrosarcoma cells by increasing αvβ3 integrin expression through the MEK/ERK/NF‐κB signal transduction pathway. J. Cell. Physiol. 226: 792–799, 2011.

Loosening of Total Hip Arthroplasty with a Prosthesis Employing a Skirted Femoral Head

In total hip arthroplasty, a modular femoral head with a flange increases the head-neck strength and compensates the leg length, but results in a decreased head-to-neck diameter ratio. Studies have shown increased chance of impingement and incidence of dislocation associated with a skirted femoral head component. However, the relation between implant loosening and the skirted neck has not been well demonstrated. We report a 41-year-old male patient with aseptic loosening of total hip arthroplasty due to osteolysis of both acetabular and femoral components 5 years after surgery. The retrieved prostheses demonstrated polyethylene wear due to impingement of the skirted head during hip flexion. Pathologic examination showed prominent foreign body reaction. Prosthetic impingement occurs due to malposition of components and extreme posture. A decreased head-to-neck diameter ratio further compromises prosthetic range of motion. A skirted femoral head component should be used with caution.

A simple mathematical standardized measurement of acetabulum anteversion after total hip arthroplasty

We invented a standardization method to measure the cup’s anteversion after total hip arthroplasty without the influence of patient’s position. We measured 68 radiographs of 10 patients after total hip replacement (THR) and calculated the error of each measurement, defined as the difference with the average of the same measuring method on the same patient. We also calculated the repeatability standard deviation (RSD) of each method according to the American Society for Testing and Materials, ASTM E691. Mean absolute inter-examination angle error, defined as the average of the absolute deviations, was 0.758 for standardized anteversion (range 0.03– 2.518), as compared with those without standardization, 2.308 (range 0.04 – 13.048). The inter-examination measurement reliability (precision), defined as one RSD, was 0.998 for standardized anteversion, as compared with those without standarization, 3.508. There is no difference between patients four and five without (p ¼ 0.097). There is a significant difference with standardization (p , 0.0001). Our study demonstrated that this mathematical method is a precise tool to measure the anteversion of the acetabular cup. We hope that it can be used widely in the future.

THR Simulator – the software for generating radiographs of THR prosthesis

BackgroundMeasuring the orientation of acetabular cup after total hip arthroplasty is important for prognosis. The verification of these measurement methods will be easier and more feasible if we can synthesize prosthesis radiographs in each simulated condition. One reported method used an expensive mechanical device with an indeterminable precision. We thus develop a program, THR Simulator, to directly synthesize digital radiographs of prostheses for further analysis.Under Windows platform and using Borland C++ Builder programming tool, we developed the THR Simulator. We first built a mathematical model of acetabulum and femoral head. The data of the real dimension of prosthesis was adopted to generate the radiograph of hip prosthesis. Then with the ray tracing algorithm, we calculated the thickness each X-ray beam passed, and then transformed to grey scale by mapping function which was derived by fitting the exponential function from the phantom image. Finally we could generate a simulated radiograph for further analysis.ResultsUsing THR Simulator, the users can incorporate many parameters together for radiograph synthesis. These parameters include thickness, film size, tube distance, film distance, anteversion, abduction, upper wear, medial wear, and posterior wear. These parameters are adequate for any radiographic measurement research. This THR Simulator has been used in two studies, and the errors are within 2° for anteversion and 0.2 mm for wearing measurement.ConclusionWe design a program, THR Simulator that can synthesize prosthesis radiographs. Such a program can be applied in future studies for further analysis and validation of measurement of various parameters of pelvis after total hip arthroplasty.

Computerized ellipse method for measuring acetabular version after total hip replacement – a precision study using synthetic and real radiographs

Background: Previous work by our group to address the problem of acetabular positioning based on 2D methods resulted in the development of a measurement method with better precision – Liaws version. This method may help the early diagnosis of acetabular loosening. In the present study, we hypothesized that our computerized ellipse method could improve the precision of measuring acetabular version. Methods: We developed our Elliversion software to measure acetabular version. Using total hip replacement (THR) Simulator, 96 radiographs were synthesized with random femoral inclination and 5° to 52° version, half with the femoral head included and half without. These synthetic radiographs and 28 real radiographs were measured with both Elliversion and the trigonometric method twice by one of the authors with a one-week interval between measurements. We then calculated the difference in the repeated measurements. Students t-test was used for statistical analysis of the measuring error and inter-measurement difference. Results: In the precision study, for synthetic radiographs including the femoral head, the ellipse method was significantly better than the trigonometric method (p < 0.01). For synthetic radiographs without the femoral head, there was no significant difference between the ellipse method and the trigonometric method (p = 0.19). As for the repeated measurements, for synthetic radiographs including the femoral head, the ellipse method was significantly better than the trigonometric method (p = 0.001), whereas for synthetic radiographs without the femoral head, there was no significant difference between the two methods (p = 0.17). For real radiographs, there was no significant difference between the two measuring methods (p = 0.12). However, if we excluded the four poor-quality radiographs, there was a significant difference between the two measuring methods (p = 0.04). Discussion: We developed a computerized ellipse method for measuring acetabular version on synthetic radiographs and good-quality real radiographs. This method is characterized by its superior precision as compared to the trigonometric method. With the 2D standardized method (Liaws version), improving the precision of measurement will help earlier diagnosis of acetabular loosening.

Direct measurement of acetabular radiographic version using an ordinary goniometer – a precision study

Objective: The acetabular version following total hip arthroplasty is an important prognostic factor. Computer navigation serves as a precise tool during hip arthroplasty, which requires precise measurement to verify the effect of the procedure. Wan and colleagues have reported an innovative method for measuring acetabular radiographic version with an ordinary goniometer. Our objective was to study the precision of this method. Methods: We derived the underlying mathematical principle of Wans method and produced a correction formula and chart. Forty-eight computer-synthesized radiographs were used to study the method and its mathematical correction. Ten real radiographs were used to detect intra-observer difference. The paired t-test was used for statistical analysis. Results: There was a significant difference between synthetic acetabular radiographic version and the measurement obtained with Wans method (p < 0.05), but there was no difference after mathematical correction (p = 0.15). For smaller radiographic version (<20o), there was no statistical difference using Wans method (p = 0.054). Conclusions: The method of Wan and colleagues can be used when acetabular radiographic version is less than 20°. For larger radiographic versions, however, mathematical correction is necessary to obtain precise results.