Biomechanical basis for elbow hinge-distractor design

Experimental studies of flexion-extension motion were carried out on five fresh elbow autopsy specimens to determine the average axis of rotation (AAR). The AAR is defined as the best fit single axis of rotation for the full range of flexion-extension. AAR was determined on all five elbows and found to approximate the center of the capitellum and trochlea. The motion of the elbows approximated a fixed axis, and the carrying angle defined in reference to humeral shaft and forearm axis decreased from 13 degrees to 22 degrees in extension to close to zero in full flexion. The average axis of rotation, with guidelines for its anatomic location, was used as the basis for the design and placement of a hinge-distractor in treating posttraumatic elbows with poor motion.

Marrow uptake index (MUI): a quantitative scintigraphic study of bone marrow in aplastic anaemia

Aplastic anaemia affects the entire bone marrow. Current methods of assessment of bone marrow function, like bone marrow biopsy or peripheral blood examination are either invasive or inadequate and cannot be expected to represent fully the changes in the entire bone marrow tissue. This prospective study was undertaken to develop and standardise a new Nuclear Medicine technique called 'Dynamic Bone marrow Imaging'. Eleven patients and ten controls were studied. Serial images of the pelvis were obtained in frame mode following intravenous injection of 185-370 mBq of 99mTc S. Colloid, and an index, called the Bone Marrow Uptake Index (P) was calculated by taking into consideration the time activity curve obtained over the iliac crest. This was followed by static imaging of the entire bone marrow in all cases. It was possible to obtain excellent information regarding topographic distribution of bone marrow as well as detect early changes in bone marrow function following treatment. An attempt was also made to correlate bone marrow cellularity as obtained by bone marrow biopsy with the results of dynamic bone marrow scintigraphy. On the basis of the encouraging results obtained in the present study, the authors feel that dynamic bone marrow imaging is an excellent technique for the objective evaluation of bone marrow in aplastic anaemia. Aplastic anaemia affects the entire bone marrow tissue. Although much progress has been made in the management of this disease, many aspects of it await better understanding. There is almost total lack of knowledge regarding the distribution of functioning marrow in various phases of aplastic anaemia, such as in relapse and remission. Current methods of assessment of marrow function rely mainly on bone marrow biopsy and peripheral blood examination. Bone marrow biopsy is invasive and cannot be expected to represent fully the changes in the entire tissue. Changes in peripheral blood picture lag behind the changes in the bone marrow. Thus, there is a need for an investigation which is safe, simple, sensitive, non invasive and capable of assessing the global function of bone marrow. Radio-nuclide imaging of bone marrow requires labelling of one or more components of this widely dispersed tissue. The reticuloendothelial and erythropoietic components can be labelled with radio-colloids and radio-iron respectively. Experimental studies have shown that the reticuloendothelial and erythropoietic elements are invariably found together in the marrow and have similar distribution. This report is based on a prospective study of bone marrow function in patients with aplastic anaemia, using 99mTc. Sulphur colloid.

Aberrant cerebrospinal fluid pathway. Detection by scintigraphy

Radionuclide cisternography is routinely performed for assessment of normal and abnormal pathways and the hydrodynamics of cerebrospinal fluid (CSF). An unusual case of a woman in whom cisternography provided the diagnosis of an iatrosenic spinopleural fistula with a large CSF collection in the pleural cavity, following surgical resection of a vertebra for a malignant tumor is presented.

The effect of the interface on the bone stresses beneath tibial components

It was proposed that the stresses in the layer of bone immediately beneath a tibial component are an important determinant of fixation durability. Using finite element analysis, (ANSYS), the stresses were determined as a function of the amount of bone resection, the localization or completeness of implant-bone contact, and the interface material. The model was of two-dimensional sagittal slices consisting of quadrilateral elements (1 mm) with a range of seventeen material properties determined by CT scans. Typical prosthesis designs shifted the center of pressure more centrally rather than posteriorly, and thus increased anterior bone stresses. Resection up to 10 mm could actually decrease bone stresses due to an increase in bone surface area as long as complete coverage was obtained. A cement interface or direct metal on bone produced identical stresses. However a 1 mm compliant interface significantly reduced stresses in regions of high elastic modulus gradient. For rigid interfaces, the contact can be irregular, which leads to areas of over and under-stressing of bone. These conclusions have implications related to implant design.

Non-Hodgkin's lymphoma in pregnancy

Pregnancy in patients who have non-Hodgkin's lymphoma is unusual. We have reported a case of diffuse, poorly differentiated lymphocytic lymphoma, stage IIIa, in a patient whose disease went into remission after she received six courses of CHOP therapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone). She became pregnant soon afterward and was delivered of a normal, full-term infant with a normal chromosomal pattern. Risk of teratogenicity appears to be negligible when chemotherapy is used during the third trimester of pregnancy.

Non-Hodgkin's lymphoma in northern India. A retrospective analysis of 238 cases

A retrospective analysis was performed of 238 patients, aged 12 years and older, with non-Hodgkin's lymphoma presenting to the All India Institute of Medical Sciences, New Delhi, India, between September 1975 and December 1982. Pathologic material was reviewed and classified according to the modified Rappaport classification. The most common histologic type encountered was diffuse histiocytic lymphoma (39%), followed by diffuse poorly differentiated lymphocytic lymphoma (29%), and diffuse mixed histiocytic and lymphocytic lymphoma (9%). Nodular lymphomas constituted 9% of all non-Hodgkin's lymphomas. A lower frequency of nodular lymphomas, a lower median age of onset (45 years), and a higher male to female ratio (4.5:1) as compared with Western countries was observed. Survival information on 90 patients revealed no effect of age, sex, stage of disease, and "B" symptoms on survival, whereas histologic diagnosis had a significant influence on survival (P less than 0.05). A median survival of 24 months in 58 patients receiving chemotherapy is comparable to that reported by other investigators.

Design of intramedullary femoral stems using computer graphics

This study describes a method for maximizing the size of an intramedullary stem which can physically be inserted into the canal of the femur. The potential applications of this are for ‘press-fit’ stems where maximizing the area of contact with the endosteal surface is likely to be important, and for cemented stems where a uniform cement layer is desirable. The 3-dimensional shape of a femur is described by using CT data of transverse sections. The computer program uses an algorithm which minimizes the amount of material removed from the stem sections, with preference being given to areas of maximum load transmission. Different parameters are investigated, such as the level and angle of the neck cut, and the length of the stem. Comparisons of percentage of the canal filled are made with standard symmetrical stems. It is shown that computer-generated stems filled substantially more than available symmetrical stems.

Physiological stresses in warehouse operations with special reference to lifting technique and gender: a case study

A field study was conducted to evaluate the effects of lifting technique (free-style vs. straight-back, bent-knee) on male workers' performances and physiological responses. A secondary objective was to study physiological stresses to female order selectors using the free-style lifting technique only. Six male and six female workers performed their routine work of grocery order selection in three different warehouses while their oxygen uptake and heart rates were measured. Workers' performances were determined using the traditional work measurement techniques (time study, methods time measurement and master standard data systems) employed by the warehouses. Total cases, weight, volume, actual and allowed time for each order were also determined. Statistical analysis showed that the performance levels of the male workers (allowed time per order * 100/actual time per order) were significantly lower and oxygen uptake and heart rates were higher for the straight-back, bent-knee method as compared to the free-style lifting technique. Male workers lifted more cases, weight and volume/min with the free-style lifting technique than with the straight-back, bent-knee method. It is concluded that the traditionally recommended straight-back, bent knee method of lifting is slower and physiologically more demanding. It is practically impossible for a substantial number of workers to meet the existing time or performance standards based on traditional work measurement techniques--when using the straight-back, bent-knee method of lifting recommended by the warehouses.(ABSTRACT TRUNCATED AT 250 WORDS)

Geometry and motion of the knee for implant and orthotic design

By analysing sections of distal femurs in the computer, and by making direct measurements, the posterior femoral condyles were shown to closely fit spherical surfaces. The center of the spheres were then used as reference points and used to define reference axes in a motion study. In flexing from 0 to 120 degrees the medial femoral condyle moved little, the lateral moved posteriorly by 17 mm, and there was an axial rotation of 20 degrees. The data were applied to implant and orthotic design and evaluation.

Nonspecific immunostimulation against viruses

A trypsinized preparation from chromogenic selected strain of Mycobacterium phlei (NSI) stimulated the recipient immune system non-specifically against a variety of viruses viz. Rabies virus (RNA virus). Marek's disease (DNA virus) and Foot and Mouth disease virus (RNA virus) in phylogenetically different hosts like mice, chicks and guinea pigs respectively. Investigation into mechanisms of such nonspecific immunostimulation revealed that there was induction of strong cell mediated immune response (CMIR) against both specific as well as to nonspecific viral antigens as evinced by LMIT, lymphokine (LyIF) assay and lymphocyte transformation test etc. There was induction of appreciable quantity of "Infectivity inhibiting substance(s)" (IIS) which was not the classical antibody (Ig) in the serum of NSI inoculated animals and birds. This substance(s) neutralized FMD, IBR, rabies and Newcastle disease virus in cell culture, mice and in embryonated eggs. Electrophoretic separation of the NSI induced serum revealed an increase in beta fraction of globulin.

A dynamic biomechanical evaluation of lifting maximum acceptable loads

A biomechanical evaluation of the job-related stresses imposed upon a worker is a potential means of reducing the high incidence rates of manual material handling injuries in industry. A biomechanical model consisting of seven rigid links joined at six articulations has been developed for this purpose. Using data from cinematographic analysis of lifting motions the model calculates: (1) body position from articulation angles, (2) angular velocities and accelerations, (3) inertial moments and forces, and (4) reactive moments and forces at each articulation, including the L5/S1 joint. Results indicated effects of the common task variables. Larger load and box sizes increased the rise times and peak values of both vertical ground reaction forces and predicted L5/S1 compressive forces. However, boxes with handles resulted in higher L5/S1 compressive forces than for boxes without handles. Also, in lifting the larger boxes the subjects did not sufficiently compensate with reduced box weights in order to maintain uniform L5/S1 compressive forces. Smoothed and rectified EMG of erector spinae muscles correlated significantly with L5/S1 compressive forces, while predicted and measured vertical ground reaction forces also correlated significantly, indicating the validity of the model as a tool for predicting job physical stresses.

Apomorphine effects on behavioral response to ethanol in mice selectively bred for differential sensitivity to ethanol

Two lines of mice selectively bred for differences in response to a hypnotic dose of ethanol were administered apomorphine alone or in combination with ethanol. When administered by itself, apomorphine produced similar dose-dependent depression of locomotor activity and increases in stereotypy in the two lines. Doses of apomorphine (0.5 microM/kg and 2 microM/kg) thought to bind only presynaptic dopamine receptors blocked the slight locomotor activation to 1.5 g/kg ethanol in the ethanol-sensitive Long-Sleep (LS) mice; in the ethanol-insensitive Short-Sleep (SS) mice which show marked activation to all subhypnotic doses of ethanol, these doses of apomorphine only attenuated the activation. A higher apomorphine dose (8 microM/kg) antagonized the locomotor depressant effects of 2.0 and 2.5 g/kg of ethanol in LS mice but did not alter the shape of the SS ethanol dose response curve for locomotor activity. Apomorphine (2 and 8 microM/kg) potentiated ethanol-induced loss of the righting reflex in LS mice in a dose dependent fashion, but did not alter this soporific effect of ethanol in SS mice. These findings extend the data base suggesting a role for dopamine both in the mechanism(s) differentiating the LS and SS mice and the stimulant and intoxicating properties of ethanol.