Arthrography after total hip arthroplasty: utility of postambulation radiographs

We compare pre-and postambulation arthrograms in 24 patients with total hip arthroplasty. In nearly half (42%) of these cases, the arthrographic evidence of a loosened prosthesis was more obvious after ambulation. Three patients (12.5%) had components which were normal by arthrographic criteria before walking, but were abnormal afterwards. We conclude that postambulation radiographs are valuable in patients who are examined for suspected loosening of prosthetic components.     

False-positive radionuclide arthroscintigraphy with a porous-coated total hip prosthesis.

The evaluation of a painful hip prosthesis for suspected loosening frequently requires a multi-modality approach. Radionuclide arthroscintigraphy is a valuable adjunct to contrast arthrography, demonstrating greater sensitivity than contrast arthrography in detecting loosening of the femoral component of the prosthesis. Despite its reliability in the evaluation of cemented hip prostheses, the value of arthroscintigraphy in patients with uncemented or porous-coated prostheses is undetermined. The case of a false-positive radionuclide arthroscintigram in a patient with an uncemented prosthesis is reported. The literature is briefly examined, and the potential implications regarding interpretation of arthroscintigraphy in patients with porous-coated prostheses are discussed.     

Chondroblastic osteosarcoma over a total hip prosthesis

Malignant transformation in the area of joint prostheses is very rare. We present the case of a woman who developed a chondroblastic osteosarcoma in the area where a total hip prosthesis had been implanted.     

Arthroscintigraphic evaluation of the painful total hip prosthesis

Arthroscintigraphy was performed in 19 patients with a painful total hip prosthesis by injecting both Tc-99m sulfur colloid and iodinated radiographic contrast material intra-articularly. Scintigraphic and radiographic results correlated exactly in 15 patients, with one false-negative scintigram, one false-positive scintigram, and one false-negative arthrogram. One patient was evaluated by scintigraphy alone. Although arthroscintigraphy is potentially more sensitive than conventional arthrography in the detection of femoral component loosening, acetabular component loosening cannot be evaluated by scintigraphy alone. A combination of scintigraphy and conventional arthrography appears to be the most accurate imaging method in the evaluation of hip prosthesis loosening.     

Bone scintigraphy in total isoelastic hip prosthesis. Proposal of a semiquantitative analysis

The authors present a method of semiquantitative analysis of bone scintigraphy in the study of the evolution of total hip prosthesis and analyse the course of remodelling processes in a group of patients who showed no post surgical complication after total isoelastic hip arthroplasty without cement. The authors will use data worked out as terms of comparison in the study of those patients who present, after surgery, a symptomatology difficult to be evaluated in order to discriminate the cases where the symptoms indicate the beginning of a pathologic process (loosening and/or infection).     

Radiologic evaluation of an adverse evolution in total hip prosthesis

The retrospective study of 50 operated cases of cemented total hip replacement and a review of the literature enabled the authors to define the radiological features of the above-mentioned condition. These features include one or more of the following signs: calcar reabsorption, lacunar erosions, modified relationships between the prosthesis components, sepsis and loosening, periarticular calcifications, dislocation and fracture of prosthesis components. Careful evaluation of these radiological features is extremely important for both an early diagnosis of failed total hip replacement and the choice of an adequate surgical treatment.     

Space orientation of total hip prosthesis. A method for three-dimensional determination

A method for in vivo determination of orientation and relation in space of components of total hip prosthesis is described. The method allows for determination of the orientation of the prosthetic components in well defined anatomic planes of the body. Furthermore the range of free motion from neutral position to the point of contact between the edge of the acetabular opening and the neck of the femoral component can be determined in various directions. To assess the accuracy of the calculations a phantom prosthesis was studied in nine different positions and the measurements of the space oriented parameters according to the present method correlated to measurements of the same parameters according to Selvik's stereophotogrammetric method. Good correlation was found. The role of prosthetic malpositioning and component interaction evaluated with the present method in the development of prosthetic loosening and displacement is discussed.     

Cemented total hip prosthesis: radiographic and scintigraphic evaluation

Conventional radiographs, technetium-99m bone scans, and gallium-67 scans were reviewed in 44 patients who had undergone cemented total hip joint replacement and were imaged because of suspicion of prosthesis loosening or infection. A complete radiolucent line of 2 mm or wider along the bone-cement interface or metal-cement lucency on conventional radiographs was used as the criterion for prosthetic loosening with or without infection and proved to be 54% sensitive and 96% specific. Scintigraphic criteria for prosthetic loosening were increased focal uptake of the radiopharmaceutical for the femoral component and increased focal or diffuse uptake for the acetabular component. For bone scintigraphy, sensitivity was 73% and specificity was 96%. Combining the results of conventional radiographs and bone scans increased sensitivity to 84% and decreased specificity to 92% for the diagnosis of loosening, infection, or both. The study also showed that Ga-67 scintigraphy has a low sensitivity for the detection of infection.     

全髋关节假体安装参数的优化组合

目的 研究满足日常生活活动范围条件下,全髋关节假体安装参数优化组合及髋臼安装角度安全范围.方法 建立人工全髋关节三维可视化计算机模型,将髋关节屈曲≥110°、屈曲90°内旋≥30°、后伸≥30°、外旋≥40°定义为日常生活活动范围一般标准;将屈曲≥120°、屈曲90°内旋≥45°、后伸≥30°、外旋≥40°定义为严格标准,头颈直径比变化范围为2～2.92,假体颈前倾角变化范围为0°～30°,髋臼假体外展角变化范围为10°～60°,髋臼前倾角变化范围为0°～70°,计算满足上述两种活动标准,臼杯外展角每变化5°,相应的髋臼假体前倾角,颈干角设定为135°.髋臼前倾角和外展角组合的安全范围定义为满足上述活动范围而没有杯颈撞击的面积.应用SAS6.12统计软件对数据进行分析.结果 髋臼角度安全范围随着头颈比增大而增大;严格标准下的安全范围比一般标准的小.颈干角135°、一般标准活动度,髋臼前倾角平均值与外展角的和加0.816倍颈前倾角等于84.76°;严格标准活动度,髋臼前倾角平均值与外展角的和加0.873倍颈前倾角等于92.04°.结论 大的头颈直径比明显增大髋臼角安全范围的面积.髋关节活动范围要求越高,髋臼角安全范围就越小,但可以通过增大头颈比来纠正.一般标准和严格标准活动度,髋臼前倾角平均值与外展角的和(Y)与颈前倾角(X)的组合分别可通过公式进行估计:Y1=-0.816X1+84.76(R2=0.993),Y2=-0.873X2 +92.04(R2=0.999).     

Three methods for determining anteversion and retroversion of a total hip prosthesis.

Three new methods to assess the degree of anteversion or retroversion of the femoral component of a total hip prosthesis are described. Compared with previously described methods, the new methods make few physical demands on the recently operated patient. The only requirement is that the affected femur be held in a neutral position parallel to the x-ray table. The methods are relatively easy to perform and are accurate and objective.