Role of mechanical factors in the evaluation of pedicle screw type spinal fixation devices.

Prior to implantation, spinal implants are subjected to rigorous testing to ensure safety and efficacy. A full battery of tests for the devices may include many steps ranging from biocompatibility tests to in vivo animal studies. This paper describes some of the essential tests from a mechanical engineering perspective (e.g., motion, load sharing, bench type tests, and finite element model analyses). These protocols reflect the research experience of the past decade or so.

Clinical profile of stroke in relation to glycaemic status of patients.

Present study was undertaken in fifty consecutive patients of acute stroke to assess the role of glycemic status on clinical profile of stroke. Majority of patients (76%) were in age group of 41-70 years. The patients were classified into four groups: euglycemics (33), known diabetics (8), newly diagnosed diabetics (6) and stress hyperglycemics (3). Diabetics as well as stress hyperglycemics had higher prevalence of larger sized severe haemorrhagic stroke with poor outcome and there was positive correlation between them.

Observation of lipid profile and lipoproteins in viral hepatitis and hepatic coma.

Lipid profile and lipoprotein levels were estimated in 35 patients of viral hepatitis, 15 patients of viral hepatitis with coma and in age and sex match 35 healthy controls. The values were compared in different groups. Levels of triglycerides were significantly raised (145.00 +/- 30.70 mg/dl) in viral hepatitis as compared to viral hepatitis with coma (111.40 +/- 16.80 mg/dl) which were similar to controls (110.8 +/- 20.6 mg/dl). Patients who recovered had higher levels of triglycerides (136.0 +/- 30.8 mg/dl) as compared to those who expired (110 +/- 15.72 mg/dl). Total serum cholesterol remained statistically unaltered in both groups. HDLc was significantly decreased in both groups, viral hepatitis (2.23 +/- 6.7 mg/dl) and viral hepatitis with coma (16.52 +/- 2.27 mg/dl) in comparison to controls (62.21 +/- 18.04 mg/dl). The levels were much lower in patients with coma than without coma. Furthermore the values were still lower in patients who expired (15.82 +/- 2.27 mg/dl) than in patients who recovered (24.13 +/- 7 mg/dl). The levels of LDLc were significantly raised in both groups, as compared with each other and in relation to mortality. VLDLc levels were significantly decreased in patients of viral hepatitis (22.13 +/- 5.8 mg/dl) as well as on viral hepatitis with coma (21.89 +/- 4.3 mg/dl). However, no significant difference was observed when compared with each other and in relation to mortality. Thus it may be concluded that isolated low value of HDLc in viral hepatitis may be used as a prognostic indicator.

Plasma lipoproteins in cortical and lacunar infarction.

Plasma lipoproteins in 30 patients of cortical infarction and 20 patients of lacunar infarction were estimated to study the relation of plasma lipids to the risk for ischaemic stroke by comparing clinical and biochemical characteristics of survivors. No significant differences were observed in the concentrations of total cholesterol, triglycerides, low density lipoproteins, very low density lipoproteins in both the groups. However patients with lacunar infarction had higher concentrations of high density lipoproteins as compared to patients with cortical infarction. These data suggest that previously demonstrated differences in HDL concentration between patients with ischaemic stroke and control subjects without stroke may be true for patients with cortical infarction but not for patients of lacunar infarction.

A study of nerve conduction velocity in patients on diphenylhydantoin therapy.

Peripheral nerve conduction studies were performed in 30 epileptics, treated with DPH and results were compared with age and sex matched controls. There was significant reduction in the amplitude of sensory nerve action potential of median (26.65 +/- 14.71 mu v) and superficial radial nerve (25.65 +/- 10.08 mu v) (p < 0.001) in DPH treated group as compared to controls, (median nerve 42.64 +/- 15.93 uv and superficial radial nerve 40.72 +/- 24.74 mu v). The results suggest that DPH causes a subclinical distal axonal neuropathy in therapeutic dosage.