A new position measurement system for micro-measurements in orthopaedics.

This paper describes both a legacy position measurement system and a new position measurement system developed for use in making accurate position measurements on the order of 1 mum (micro-measurements) specifically related to the evaluation of orthopaedic implants during simulated use. Commercially available components including an off the shelf position sensor and off the shelf data acquisition hardware are integrated with a signal conditioner designed around off the shelf components, and custom written software in the new measurement system. This new system exhibits marked improvements in cost, accuracy, range and ruggedness over the legacy measurement system used for the same purpose, and has been adopted for the evaluation of orthopaedic implants.

Analysis of gene expression in carbon tetrachloride-treated rat livers using a novel bioarray technology.

The present study successfully utilizes a new ADME Rat Expression Bioarray, containing 1040 metabolism- and toxicology-linked genes, to monitor gene expression from the livers of rats treated with carbon tetrachloride (CCl(4)). Histopathological analysis, hierarchical clustering methods, and gene expression profiling are compared between the control and CCl(4)-treated animals. A total of 44 transcripts were found to be altered in response to the hepatotoxin, 19 of which were upregulated and 25 were downregulated.

Biphasic poroviscoelastic characteristics of proteoglycan-depleted articular cartilage: simulation of degeneration.

This study investigated the biphasic poroviscoelastic properties of normal and proteoglycan-depleted articular cartilage to validate this model for use in the diagnosis of degenerated cartilage. A normal control group, a buffer-treated control group, and a trypsin-treated proteoglycan-depleted experimental group were investigated. Water content and glycosaminoglycan concentration were measured for each group in order to assess the affects of buffer treatment and trypsin treatment on normal articular cartilage.

Effects of hyaluronate sodium on pain and physical functioning in osteoarthritis of the knee: a randomized, double-blind, placebo-controlled clinical trial.

Background: Intra-articular hyaluronate sodium is a relatively new therapy for the treatment of osteoarthritis of the knee. This randomized, double-blind clinical trial was conducted at a large primary care medical center to determine the impact of hyaluronate sodium vs conventional therapy on measures of pain, stiffness, and disability at rest and following functionally relevant walking and stepping activities.

Methods: A total of 120 patients (mean age, 67 years) with unilateral grades 1 to 3 medial compartment knee osteoarthritis were randomized to 1 of 4 treatment groups: group 1, 2 mL of hyaluronate sodium at a concentration of 10 mg/mL and placebo (100 mg of lactose); group 2, nonsteroidal anti-inflammatory drugs (NSAIDs) (75 mg of diclofenac and 200 microg of misoprostol) and hyaluronate sodium; group 3, NSAIDs and placebo (2 mL of isotonic sodium chloride solution [saline]); and group 4, placebo (lactose and saline).

Biphasic poroviscoelastic simulation of the unconfined compression of articular cartilage: II--Effect of variable strain rates.

This study investigated the abilities of the linear biphasic poroviscoelastic (BPVE) model and the linear biphasic poroelastic (BPE) model to simulate the effect of variable ramp strain rates on the unconfined compression stress relaxation response of articular cartilage. Curve fitting of experimental data showed that the BPVE model was able to successfully account for the ramp strain rate-dependent viscoelastic behavior of articular cartilage under unconfined compression, while the BPE model was able to account for the complete viscoelastic response at a slow strain rate, but only the long-term viscoelastic response at faster strain rates. We concluded that the short-term viscoelastic behavior of articular cartilage, when subjected to a fast ramp strain rate, is primarily governed by a fluid flow-independent (intrinsic) viscoelastic mechanism, whereas the long-term viscoelastic behavior is governed by a fluid flow-dependent (biphasic) viscoelastic mechanism.