Biomedical subjects

J C Eck

Publications and source records attributed to J C Eck.

23 records · Page 2Linked to original sources

PubMed1998

Oblique MRI as a useful adjunct in evaluation of cervical foraminal impingement.

Magnetic resonance (MR) imaging is considered the gold standard for soft-tissue disease. The traditional MR imaging series uses axial and sagittal views. The purpose of this study was to demonstrate that oblique MR imaging provides valuable information about the cervical foramen not available from the conventional MR imaging technique. Ten asymptomatic individuals volunteered for MR imaging. Measurements were taken of height, width, and area for the nerves and foramen at the entrance and mid zones. Nerves were graded as normal, contacted, or deformed. Normal foraminal morphology in asymptomatic individuals and characteristics that compromise the space available for the nerve root were identified. Nerves with minimal or no contact had significantly greater foraminal widths than nerves with significant contact. Although there was a correlation between nerve contact and foraminal width, regression analysis did not demonstrate a correlation between disc height and foraminal size.

Adult↗

PubMed1998

Diagnosis and treatment of common metabolic spinal disorders in the geriatric population.

BACKGROUND: Bone is constantly resorbed and remodeled throughout life. After approximately age 30, there is a net loss of bone mass. This places the geriatric population at an increased risk of pathologic bone disorders that can lead to fractures and deformity. METHODS: In this paper, we review bone metabolism and remodeling and introduce the proper diagnostic techniques. The most common pathologic spinal disorders are introduced, with emphasis on presentation and treatment options. RESULTS: To prevent excessive bone loss, patients should be educated on proper nutrition (calcium and vitamin D requirements) and lifestyle (avoiding alcohol and cigarette smoking). Sex hormone and drug therapies are available to reduce bone loss. New bisphosphonates such as alendronate sodium (Fosamax) have been effective in increasing bone mass. CONCLUSIONS: Early diagnosis and proper treatment of pathologic bone disorders can reduce the incidence of fracture and allow the patient a more productive and comfortable life.

Adult↗

PubMed1997

A noninvasive, three-dimensional spinal motion analysis method.

STUDY DESIGN: A three-dimensional, noninvasive motion analysis method was developed by monitoring the orientation of the principal axes of each vertebra. OBJECTIVES: To develop a method of performing three-dimensional, noninvasive motion analysis of the spine using computed tomography data. SUMMARY OF BACKGROUND DATA: The concept of using principal axes of the moment of inertia tensor to measure the orientation and position of a rigid body has been applied to the wrist and subtalar joints, but has not yet been applied to the spine. METHODS: Scans were taken of two isolated vertebrae in various known positions. Centroids, area, moments, and product of inertia of each scan were determined using a commercial program. Custom software combined data using the parallel axis theorem to give three-dimensional data for each vertebra. Changes in the centroid and principal axes were used to calculate translation and rotation, respectively. RESULTS: The system accuracy was within 1.0 degree in rotation and 1.0 mm in translation. Some errors occurred in minor motions when a smaller number of scans were used. System resolution was 0.43 mm. CONCLUSIONS: A system has been developed capable of calculating three-dimensional spinal motion based on measurements of a series of computed tomography images. The system has an accuracy similar to that of current motion analysis methods, but future studies will be necessary to apply this system in vivo.

Cadaver↗

PubMed1997

Laparoscopic assisted fusion of the lumbosacral spine. A biomechanical and histologic analysis of the open versus laparoscopic technique in an animal model.

STUDY DESIGN: An animal model for laparoscopic lumbosacral fusion. OBJECTIVES: To compare the biomechanical and histologic results of open to laparoscopic lumbosacral discectomy and fusion in an animal model. BACKGROUND DATA: Early clinical reports of laparoscopic lumbosacral fusions are encouraging, but animal experiments have not been reported. METHODS: Ten pigs (50-80 kg) were divided into two groups. Group 1 underwent an open anterior lumbosacral discectomy and fusion at L7-S1 using autologous bone graft and a titanium MOSS (DePuy Motech) cage. Group 2 was identical to Group 1 except that a laparoscopic technique was used. The animals were killed at 3 months, and the lumbosacral spines were harvested for biomechanical and histologic testing. RESULTS: Estimated blood loss and average length of operation, respectively, for the two groups were: Group 1, 50 mL, 2 hours 50 minutes; and Group 2, 40 mL, 3 hours 40 minutes. There were no perioperative or postoperative complications in either group. Motion analysis results showed less motion in lateral bending, flexion, and extension than in the intact specimen in both groups. Tensile testing showed that the stiffness was significantly greater in the open group than in the laparoscopic group (P < 0.004). Histologic examination showed a less extensive discectomy and less bone growth in the implant in the laparoscopic group. Inadequate decortication of end-plates occurred in two animals who underwent laparoscopy. CONCLUSIONS: Although lumbosacral discectomy and implant insertion can be performed using the laparoscopic technique, the construct may not have the same biomechanical strength as that attained with the open procedure. Laparoscopic-assisted lumbosacral fusion surgery requires additional investigation before it is widely used in clinical situations.

Animals↗

PubMed1996

Biomechanics of transfixation in pedicle screw instrumentation.

STUDY DESIGN: The biomechanical role of transfixation in pedicle screw instrumentation was investigated using flexibility tests and finite element analyses. OBJECTIVE: To assess the stabilizing effect of use and position of transfixators. SUMMARY OF BACKGROUND DATA: Transfixation is common in pedicle screw instrumentation, however, its biomechanical role and optimal position are not completely understood. METHODS: Specimens underwent nondestructive flexibility tests using a three-dimensional motion analysis system. Tests compared the intact spine with instrumentation with and without transfixators Rotational angles of the superior vertebra, resulting from the maximum moment of 6.4 Nm, were compared. Three-dimensional finite element models investigated transfixator position. Rotations of the superior vertebra were compared for cases with and without transfixators to determine the position providing the greatest stability. RESULTS: Biomechanical test showed that only axial rotational stability significantly improved with transfixators compared with instrumentation alone. Pimte element models predicted improvement in lateral bending and axial rotation with transfixators compared with the case with no transfixator. With one transfixator, the greatest improvement in axial rotation stability occurred with the transfixator at the proximal 1/4 position of the rods. When two transfixators were used, the optimal locations were with one transfixator in the middle and the second at the proximal 1/8 position. CONCLUSIONS: Transfixators improved the stabilizing effects of pedicle screw instrumentation. The greatest axial rotation stability was obtained with two transfixators; one in the middle and the other at the proximal 1/8 position of the longitudinal rods.

Animals↗