PubMed Health⌕ Search

Biomedical subjects

N Langrana

Publications and source records attributed to N Langrana.

6 recordsLinked to original sources
PubMed1997

Computerized hand diagnostic/rehabilitation system using a force feedback glove.

This paper describes recent results of a unified computerized system for hand diagnosis and rehabilitation. Automatic diagnosis data collection and Virtual Reality rehabilitation exercises are the main characteristics of the system. The diagnosis subsystem includes a tactile sensing glove in addition to standard devices such as electronic dynamometer, pinchmeter and goniometer. Three standard rehabilitation exercises were simulated in a Virtual Reality environment, using the WorldToolKit graphics library. The first two exercises (ball squeezing and DigiKey) allow measurement of finger forces exerted during the rehabilitation routine. The third exercise (Peg board) involves the patient's visual-motor coordination. The rehabilitation subsystem uses a VPL DataGlove retrofitted with Rutgers Master (RM-I) and its interface. The exercises involve manipulation of objects with different stiffnesses and geometry. Grasping forces were modeled and fed back using the Rutgers Master worn on patient's hand. Data is gathered in real time from both diagnosis and rehabilitation subsystems. Finger specific forces recorded during rehabilitation exercises allow better diagnosis of the patient impairment. An ORACLE database is used to store and manipulate patients' records. Proof of concept trials were performed in a clinical environment. Some results of patient records analysis are presented in this paper. A new version of the system using an RM II haptic interface is presently under consideration.

Adult↗
PubMed1989

Tension band wiring-bone grafting for spondylolysis and spondylolisthesis. A clinical and biomechanical study.

Patients with spondylolysis or spondylolisthesis with persistent symptoms often require surgical treatment. The purpose of this article is to present a new surgical technique and clinical results of 13 patients with symptomatic spondylolysis/spondylolisthesis who were treated with tension band wiring (intra- or intersegmental) and bone grafting techniques. This article also presents the results of biomechanical effects of these tension band wiring methods on canine lumbar spines with experimental spondylolytic defects. Thirteen adult patients, three with spondylolysis, and ten with spondylolytic spondylolisthesis, were treated with intrasegmental or intersegmental wiring with bone grafting technique, and the clinical results were evaluated at the mean follow-up period of 20 months. Patients with spondylolysis were treated with intrasegmental wiring (transverse processes to the spinous process of the same segment) with bone grafting at the lytic defect. Patients with spondylolytic spondylolisthesis were treated with intersegmental wiring (transverse process of the segment with defect to the spinous process of the same segment and to the spinous process of the segment below) with bone grafting to the defect and one-level fusion. All 13 patients had a solid spinal fusion and/or healing of the defect at the follow-up evaluation. Eleven had excellent clinical results; one a good, and one a fair result. The results of the biomechanical study showed that the experimental spondylolytic defect produced a significant decrease in bending stiffness (flexion-extension), and the wiring techniques (both the intra- and intersegment) increased the bending stiffness to that of the normal intact spinal segment.

Adult↗
PubMed1989

Bone attachment to hydroxyapatite coated polymers.

Bone attachment to two classes of hydroxyapatite (HA) coated polymers was evaluated mechanically and histologically. Particulate HA was molded into the surface of thermoplastic implants and cast into the surface of thermoset implants. Coated and uncoated implants of both types were implanted in the distal femurs of rabbits for four and twelve weeks. After sacrifice, the bone/implant interface was evaluated mechanically via a push-out test with a servohydraulic test system. Paired statistical analysis revealed significantly greater shear strengths for coated vs. uncoated implants for both polymer systems at both time periods. Mixed mode of failure occurred with particle removal from the polymer surface and from the bone. One animal at each time period was saved for histology. Histology at both time periods indicated direct bone apposition to the HA coating as compared to a fibrous encapsulation about the uncoated implants. This was confirmed with backscatter scanning electron microscopy and scanning acoustic microscopy. Hydroxyapatite coatings significantly improve the bond strength between polymers and bone by allowing direct bone apposition and some mechanical interlocking with the bone.

Animals↗
PubMed1982

A phalangeal fracture model--quantitative analysis of rigidity and failure.

Nine types of internal fixation techniques were tested in 4-point bending using a pig metacarpal model for phalangeal fractures. Levels of bending rigidity and bending moments at failure were determined, and the modes of failure are described. Plate and screw fixation afforded the greatest rigidity, and epiphyseal fractures occurred, leaving intact the test section. Flexible wire loop fixation failed by wire cutting into bone when a square knot was used. Twisted wire unraveled when placed in tension. Depending on the fracture type and the wire placement. Kirschner wires failed either by slipping in the bone, twisting in the bone cortex, or bending at the bone cortex interface. Rigidity varied widely depending on the way in which the wires were employed.

Animals↗