Review of orthopaedic manipulator arms.

Trajectory planning and implementation forms a substantial part of current and future orthopaedic practice. This type of surgery is governed by a basic orthopaedic principle [1] which involves the placement of a surgical tool at a specific site within a region, via a trajectory which is planned from X-ray based 2D images and governed by 3D anatomical constraints. The accuracy and safety of procedures utilising the basic orthopaedic principle depends on the surgeon's judgement, experience, ability to integrate images, utilisation of intra-operative X-ray, knowledge of anatomical-biomechanical constraints and eye hand dexterity. The surgeon must remain as the responsible medical expert in charge of the overall system. At the same time the surgeon covets the accuracy offered by Computer Assisted Surgery including a manipulator. A summary of current inadequacies of manipulators indicates that the main drivers for future work are that accuracy is critical in close contact with the environment, safety concerns dictate manipulator geometry and technological limitations are many. In any effort to develop an optimal manipulator to guide surgical instruments and tools it is an obvious first step to review and categorise current manipulators. The aim of this paper is to review all aspects of manipulator design against the five main criteria of ergonomics; safety; accuracy; sterility and measurable benefits such as reduced operative time, reduced surgical trauma and improved clinical results.

Hyperlipidemia after renal transplantation in children.

A cross-sectional survey of 32 children who received renal allografts was undertaken to evaluate lipid profiles in a pediatric transplant population. Ages ranged from 8 to 18 years, and serum creatinine concentrations varied from 0.5 to 5.6 mg/100 ml (mean, 1.4 mg/100 ml). Fifty percent of patients showed an abnormal lipoprotein electrophoresis, and these were evenly divided between type II and type IV patterns. The data suggest that patients with type II pattern tend to be receiving higher doses of prednisone, and increasing levels of cholesterol and triglyceride are also associated with higher corticosteroid dosages. In contrast to the observations of others in dialysis patients, measurements of glucose metabolism such as fasting blood sugar and fasting insulin levels were not associated with lipid abnormalities in this population. Lipid abnormalities following renal transplantation in children are similar to those described in adults, and may contribute to morbidity in the years following successful renal transplantation.

The effects of varying dialysis regimens on lymphocyte stimulation.

A protocol was designed to alter mean time average serum concentrations of "middle" (B12) and "small" (urea) molecules. Serum before and after studies was tested for its effect on the blastogenic response to PHA. From this study we have concluded that: 1. Serum of patients on hemodialysis inhibits the mitogenic response of normal lymphocytes to PHA when compared to normal sera. 2. This phenomenon is not responsive to pertubations in dialysis designed to alter the concentration of ""middle'' and ""small'' molecules. 3. The inverse correlation between PHA response and serum PO4 and likewise the inverse correlation with changes in bone X-rays suggest that PTH, fragments thereof, or other factors related to bone and calcium metabolism, could conceivably be involved. This could mediated via cyclic AMP.