Biomedical subjects

J J Crisco

Publications and source records attributed to J J Crisco.

At least 37 records · Page 2Linked to original sources

PubMed1996

Maximal contraction lessens impact response in a muscle contusion model.

The effect of muscle contraction on a contusion injury model was studied in the gastrocnemius muscle of anesthetized rats. Both limbs of 18 rats received a contusion injury with a blunt non-penetrating impact. One hind limb was relaxed during impact and the other was electrically stimulated to tetanic contraction. The impact was produced using a drop-mass technique (mass = 171 g, height = 101 cm, spherical radius of impactor tip = 6.4 mm). The impact response was determined by sampling (10 kHz) the transmitted impact force and the displacement of the impactor. In a subgroup of nine rats, the severity of the contusion injury was measured by recording contractile tension in twitch and tetanus within two hours of injury. We found that the peak impact force was significantly less (p < 0.01), while the peak impact displacement was significantly greater (p < 0.01) in the contracted limb. Correspondingly, the impact stiffness of the contracted limb was significantly less (p < 0.01) than the impact stiffness in the relaxed limb. Both impacts produced significant injuries relative to an uninjured control group. The tetanic tension (31 +/- 4 N) generated by the muscles that were contracted during impact was significantly (p < 0.03) greater than that generated by the muscles that were relaxed during impact (27 +/- 4 N). The findings from this specific model indicate that the impact response of the limbs with relaxed muscle was dominated by the underlying bone, while maximally contracted muscle decreased the influence of the bone and lessened the impact response. Maximally contracted muscle was not more susceptible to injury and may act as protective mechanism against some impacts.

Animals↗

PubMed1996

The reinforcement of cancellous bone screws with calcium phosphate cement.

The ability of calcium phosphate cement (CPC) to reinforce cancellous screws placed in previously stripped holes was studied in vitro. The distal end of canine femurs were harvested. A total of 15 screws were placed in six femurs. The pullout strength (failure force), failure displacement, stiffness, and energy absorbed were determined for the screws in the intact cancellous bone. Next, these stripped screw holes were packed with CPC. The pullout test was repeated, and the results were compared using a paired, Student's t test. We found that the CPC was able to reinforce the previously stripped holes and significantly increase the pullout strength (1,159 +/- 278 N versus 678 +/- 297 N) and the stiffness (1,990 +/- 569 N/mm versus 1,519 +/- 609 N/mm) of the constructs, as well as the energy absorbed by the constructs until failure (467 +/- 180 N.mm versus 278 +/- 140 N.mm). There was no difference in the failure displacement (0.94 +/- 0.23 versus 0.85 +/- 0.51 mm). This study documents the ability of CPC to acutely reinforce cancellous bone screws in a region with no or poor-quality cancellous bone.

Animals↗

PubMed1996

Radiographic progression to dorsal intercalated segment instability.

We present a case of an acute hyper-extension wrist injury that progressed from normal carpal alignment to dorsal intercalated segment instability over a short period of time. Disruption of the scapholunate interosseous and radioscapholunate ligaments was proven arthroscopically, while the intercapsular ligaments were demonstrated to be intact. We have shown that lunate malalignment can occur over time, as secondary lunate ligamentous supports attenuate under abnormal carpal kinetics.

Accidental Falls↗

PubMed1995

Two-dimensional rigid-body kinematics using image contour registration.

A method for calculating two-dimensional rigid-body kinematic parameters using shape features is presented. Proposed applications include the noninvasive quantification of planar joint motion in vivo. By using digitized images (computed tomographs, radiographs, etc.) of a bone contour at two positions, the contour curvatures can be 'best-fit' to obtain a one-to-one mapping or registration of the bone images. This produces a dense field of displacement vectors from which planar rigid-body kinematic parameters can be estimated. Accuracy was studied using radiographic images of cadaveric femoral bone. The two motions of pure rotation with a fixed center of rotation and of pure translation were simulated. For pure rotation, error in rotation was independent of the rotation magnitude, with an average (n = 10) error of 0.3 +/- 0.8 degrees. The translation error averaged 0.9 +/- 0.5 mm. For pure translation, the error in rotation was -0.01 +/- 0.69 degrees and the error in translation was -0.62 +/- 0.98 mm (n = 10). This novel method has broad applications in the field of planar kinematics, especially in cases for which marker fixation is neither possible nor practical.

Algorithms↗

PubMed1994

On the understanding of clinical instability.

STUDY DESIGN: Three-dimensional flexibility changes due to the application of an external fixator at C4-C5 were studied in cervical spine specimens. OBJECTIVES: To evaluate the biomechanical effects of applying a cervical external fixator to a patient using an in vitro model. SUMMARY OF BACKGROUND DATA: There is controversy regarding the relationship between the changes in spinal motion and clinical instability. METHODS: Using fresh cadaveric C4-C7 specimens, multidirectional flexibility was measured at all vertebral levels, before and after the fixator application at C4-C5, C5-C6, and C4-C6. RESULTS: The average ranges of motion for flexion, extension, lateral bending, and axial rotation were 8.3 degrees, 7.2 degrees, 5.3 degrees, and 5.6 degrees, which decreased by 40%, 27%, 32%, and 58%, respectively, because of the fixator application. The corresponding neutral zones were 3.4 degrees, 3.4 degrees, 3.0 degrees, and 2.0 degrees, which decreased by 76%, 76%, 54% and 69%, respectively. The decreases with the fixation at C4-C5 were similar to those for fixation at C5-C6. CONCLUSIONS: This in vitro study documented that the application of an external fixator to the cervical spine decreases the intervertebral motion in general, and decreases flexion, extension and torsional neutral zones in particular. The findings help explain the clinical instability of the spine and support the hypothesis that the neutral zone is more closely associated with the clinical instability than is the range of motion.

Adult↗

PubMed1994

Disc degeneration affects the multidirectional flexibility of the lumbar spine.

STUDY DESIGN: An in vitro biomechanical investigation using human lumbar cadaveric spine specimens was undertaken to determine any relationship between intervertebral disc degeneration and nonlinear multidirectional spinal flexibility. SUMMARY OF BACKGROUND DATA: Previous clinical and biomechanical studies have not established conclusively such a relationship. METHODS: Forty-seven discs from 12 whole lumbar spine specimens were studied under the application of flexion-extension, axial rotation, and lateral bending pure moments. Three flexibility parameters were defined (neutral zone (NZ), range of motion (ROM), and neutral zone ratio (NZR = NZ/ROM)) and correlated with the macroscopic and radiographic degeneration. RESULTS AND CONCLUSIONS: In flexion-extension, the ROM decreased and NZR increased with degeneration. In axial rotation, NZ and NZR increased with degeneration. In lateral bending, the ROM significantly decreased and the NZR increased with degeneration. In all three loading directions, the NZR increased, indicating greater joint laxity with degeneration.

Adult↗

PubMed1994

Optimal marker placement for calculating the instantaneous center of rotation.

A computer simulation with error propagation was performed to determine the optimal placement of marker points for calculating the instantaneous center of rotation (CRi). The authors assume that planar rigid body motion occurs between two positions, each defined by marker points. Noisy marker points were generated by perturbing their coordinates with random values from a normal population of errors. The effects of these errors on the range of errors in calculating CRi location were investigated. Parametric analysis determined that marker point placement had important effects on CRi error. Marker placement was optimal when the estimated CRi was located at the midpoint between the marker points. While increasing the distance between marker points increased accuracy, there is a critical distance above which no additional increase in accuracy was noted when using this placement. The farther the marker midpoint was from the CRi, the greater was the error. At these placements, increasing the distance between the marker points continually decreased CRi error. The methodologies presented here help to improve the accuracy with which the location of the CRi can be calculated. However, it is emphasized that the CRi remains sensitive to noise and investigations should apply this kinematic parameter knowingly.

Biomechanical Phenomena↗

PubMed1994

Mechanical evaluation of the scaphoid shift test.

Manipulative examination of the carpal bones is an important facet of the examination of the wrist. Abnormal translation of portions of the carpus in response to applied force is a commonly used clinical indicator of ligament injury. Unilateral scaphoid hypermobility during the so-called scaphoid shift test is felt to represent traumatic instability, especially in the context of wrist injury. The test, however, is subjective, and requires considerable experience to correlate the degree of scaphoid mobility with pathologic significance. We used an instrument that quantifies the load-displacement behavior of the scaphoid and its supporting ligaments during application of a dorsally directed load at the scaphoid tubercle. We evaluated 18 uninjured (normal) wrists with clinical ligament examination and with mechanical testing. Subjects who exhibited a positive scaphoid shift had significantly increased displacement and significantly decreased stiffness when compared with subjects who did not have a shift.

Adult↗

PubMed1994

Mechanical behavior of the human lumbar and lumbosacral spine as shown by three-dimensional load-displacement curves.

The lumbar region is a frequent site of spinal disorders, including low-back pain, and of spinal trauma. Clinical studies have established that abnormal intervertebral motions occur in some patients who have low-back pain. A knowledge of normal spinal movements, with all of the inherent complexities, is needed as a baseline. The present study documents the complete three-dimensional elastic physical properties of each lumbar intervertebral level from the level between the first and second lumbar vertebrae through the level between the fifth lumbar and first sacral vertebrae. Nine whole fresh-frozen human cadaveric lumbar-spine specimens were used. Pure moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied, and three-dimensional intervertebral motions were determined with use of stereophotogrammetry. The motions were presented in the form of a set of six load-displacement curves, quantitating intervertebral rotations and translations. The curves were found to be non-linear, and the motions were coupled. The ranges of motion were found to compare favorably with reported values from in vivo studies.

Adult↗

PubMed1993

Posture affects motion coupling patterns of the upper cervical spine.

Measurements of motions of the cervical spine are used to help diagnose the problems of clinical instability due to degenerative changes and trauma. For a better interpretation of the three-dimensional motions of the upper cervical spine, knowledge of the effects of posture on these motions is necessary. Seven fresh human cadaveric C0-C3 spinal specimens were utilized. Each specimen was put in three distinct sagittal plane postures: full flexion, neutral, and full extension. At each posture, two load types were applied: left and right axial torques, and left and right lateral bending moments up to 1.5 Nm. The resulting three-dimensional relative motions of C0-C1 and C1-C2 were measured, with use of nonconstraining stereophotogrammetry, in the form of load-displacement curves. We found that the curves were nonlinear. The most dramatic change due to modification in posture was found in coupled sagittal plane rotation, which changed from extension at extended posture to flexion at flexed posture at both levels and in response to both load types. For the axial torque, the main axial rotation and coupled lateral bending changed little with posture. For the lateral bending moment, the main lateral bending rotation and coupled axial rotation decreased; the latter changed direction at C1-C2 as the spine was put into flexed posture. The motions for the right and left load applications generally were mirror images, except for the coupled sagittal plane rotations, which did not change with the direction of the load.

Adult↗

PubMed1993

The volume of motion: introduction, derivation, and an application comparing various spinal fixation devices.

Range of motion (ROM), the displacement between two limits, is one of the most common parameters used to describe joint kinematics. The ROM is a one-dimensional parameter, although the motion at many normal and pathological joints is three-dimensional. Certainly, the ROM yields vital information, but an overall measure of the three-dimensional mobility at a joint may also be useful. The volume of motion (VOM) is such a measure. The translational VOM is the volume defined by all possible ROMs of a point on a rigid body. The rotational VOM, although its interpretation is not as tangible as the translational VOM, is a measure of the three-dimensional rotational mobility of a rigid body. The magnitude of the VOM is proportional to mobility; the VOM is a scaler, which does not contain any directional information. Experimental determination of the VOM is not practical since it would require applying loads in an infinite number of directions. The mathematical derivation given here allows the VOM to be calculated, with the assumption of conservative elasticity, from the resultant displacements of three distinct load vectors of equal magnitude. An example of the VOM is presented in the comparison of the biomechanical stabilizing potential of various spinal fixation devices.

Biomechanical Phenomena↗

PubMed1993

Posterior element strength six months postinjury in the canine cervical spine.

In vivo and in vitro biomechanical studies from this research group revealed that acute differences in the range of motion of C4-C5 canine cervical spine injuries decreased over a 24-week healing period to approach control values. It could be inferred that the repair tissue replacing the injured posterior elements functionally returned the spine to normal. This study investigated the biomechanical properties of the healed tissue and the isolated adjacent posterior elements at each intervertebral level of these same specimens. Twenty-two animals underwent one of four procedures at the C4-C5 level: (a) sham procedure, (b) transection of the supra- and interspinous ligament, (c) laminectomy, or (d) laminectomy plus bilateral facetectomy of the inferior articular facets. Twenty animals survived the entire testing protocol. Twenty-four weeks after injury, destructive testing was performed on the isolated posterior elements in tension loading. The maximum load, elongation at maximum load, stiffness, and energy absorbed to the maximum load were measured. The posterior elements injured by all of the procedures behaved similarly across all experimental groups after 24 weeks of healing. A trend for decreased stiffness in the more extensive surgery groups was seen, but no statistically significant differences were found. This paralleled the results of prior in vivo and in vitro range-of-motion testing.

Animals↗

PubMed1992

The effect of injury on rotational coupling at the lumbosacral joint. A biomechanical investigation.

The lumbosacral joint is frequently indicated as a source of low-back pain, a cause of which may be abnormal patterns of vertebral motions. The goal of this study was to describe the influence of injury on the coupled motions of the L5-S1 joint in a human cadaveric model. Nine whole lumbosacral spine specimens were studied under the application of flexion, extension, left/right axial torque and right/left lateral bending pure moments. Injuries to the posterior ligaments, intervertebral disc, and articular facets at L5-S1 were produced, and the motion at L5-S1 was determined after each sequential injury. No significant coupled rotations were observed under flexion or extension moments. Under axial torque, lateral rotation at L5-S1 occurred to the same side as the applied torque and increased significantly only after injury to the intervertebral disc. Also coupled to axial torque was flexion rotation in the intact specimen, which became extension rotation after facetectomy. Under lateral bending moments, coupled axial rotation was to the opposite side of the applied moment and increased significantly only after removal of the facets of L5. Based on these results, it was concluded that intervertebral disc most resisted the coupled motion of lateral rotation under the application of axial torque, whereas the articular facets most resisted the coupled axial rotation under the application of lateral bending at the lumbosacral joint. Also, the facets were the structures that produced the flexion rotation of L5 on S1 under axial torque loading.

Back Pain↗

PubMed1992

Biomechanical evaluation of four different posterior atlantoaxial fixation techniques.

Four different techniques for posterior atlantoaxial fusion were tested in vitro: 1) wire fixation with one median graft (Gallie type); 2) wire fixation with two bilateral grafts (Brooks type); 3) transarticular screw fixation (Magerl); and, 4) two bilateral posterior clamps (Halifax). The experiment was designed to determine the immediate three-dimensional stability of the spinal construct. Ten fresh human cadaveric specimens were tested intact, injured, and instrumented with each of the fixation techniques. The injury consisted of a severe soft tissue injury model, in which the alar, transverse, and capsular ligaments were transected. The three-dimensional motions of C1 relative to C2 were measured as the specimens were subjected to loads of pure moments in flexion-extension, axial rotation, and lateral bending. Each fixation technique significantly decreased motion in all directions, as compared to the intact and injured spines. We found that the Gallie system generally allowed significantly more rotation in flexion, extension, axial rotation, and lateral bending than the other three fixation techniques. There was generally no significant difference between the amount of rotation with the other three fixation techniques. However, the Magerl technique tended to allow the least rotation. The anteroposterior translation of two points on C1 were about equal for all fixation techniques.

Atlanto-Axial Joint↗

PubMed1992

Multidirectional instabilities of experimental burst fractures of the atlas.

For the purpose of understanding the acute instability of a burst (Jefferson) fracture of the atlas, the authors produced the fractures experimentally and measured multidirectional flexibilities in seven cadaveric C0-C3 specimens. The flexibilities were measured by the authors' standardized method: they applied six types of physiologically pure moments (up to 1.5 Nm) and recorded the ensuing C0-C2 motions by stereophotogrammetry. The flexibility tests were performed before and after the production of the fracture. The greatest increase in flexibility due to the injury was in flexion-extension (+22.0 degrees, 41.7%). In lateral bending, the increase was 7.7 degrees, or 23.9%. The flexibility was mostly maintained in axial rotation (+4.8 degrees, 5.4%). The increase in motion was due to an increase in neutral zone in flexion-extension, and an increase in the elastic zone in lateral bending. These flexibility results of experimentally produced fractures reflect quite well the acute instabilities seen clinically.

Cervical Atlas↗

PubMed1991

Effects of alar ligament transection on upper cervical spine rotation.

Fresh human cadaveric specimens of occiput (C0) to C3 were subjected to axial torque. The resulting physiological motions were studied in an unconstrained three-dimensional manner. Effects of sequential transections of the left and right alar ligaments on the relative motions of C0-C1 and C1-C2 were studied. After transection of the left alar ligament, ranges of motion--due to 1.5 Nm torque--increased at both the C0-C1 and C1-C2 joints. Increases were small, on average 1.9 degrees to each side and at each level. Increases due to subsequent cutting of the right alar ligament were, on average, only 0.5 degrees and statistically not significant. In general, neutral zones showed greater increases, e.g., 3.9 degrees to each side at the C1-C2 joint. Comparing right and left axial rotations, after transection of the left alar ligament, showed greater percentage increases for the right, as compared to the left, axial rotation, at both C0-C1 and C1-C2 joints. Functional loss of the alar ligaments indicates a potential for rotatory instability, which, however, must be determined in conjunction with other clinical findings, such as neurological dysfunction, pain, and deformity.

Adult↗

PubMed1991

Bone graft translation of four upper cervical spine fixation techniques in a cadaveric model.

The goal of spinal fixation is to promote bony fusion by restricting motion at the site of the bone graft. Therefore, in order to evaluate the efficiency of various cervical fixation techniques, we determined the translations at the posterior arch of C1 for four C1-C2 posterior techniques: Gallie, Brooks, Magerl, and Halifax. Our model was the cadaveric specimen, with extensive soft tissue injury: transection of the alar, transverse, and capsular ligaments. Under three-dimensional physiological loading, we recorded the motion of C1 relative to C2, and calculated the translations at the surface of the graft in three dimensions, 10 specimens being tested intact, injured, and instrumented with each of the techniques. We assumed that translational laxity or neutral zone was the critical motion parameter and evaluated it, quantified herein as the neutral zone, at seven points at the graft site. The three-dimensional neutral zone translations were analyzed by their axial and shear components. We found that there was no significant difference with the fixation techniques in the average axial translation (Brooks: 1.1 mm; Magerl: 1.3 mm; Gallie: 1.5 mm; and Halifax: 0.5 mm). In shear, the Magerl averaged 1 mm, which was significantly less than the Gallie (2.1 mm). The Brooks (1.6 mm) and Halifax (1 mm) were not different from each other, Magerl, or Gallie. We propose that evaluation by translational laxity (neutral zone) at the graft site is a noteworthy concept in biomechanical analysis.

Adult↗

PubMed1991

A model of the alar ligaments of the upper cervical spine in axial rotation.

Although there are seven vertebrae in the human cervical spine, over 50% of the total axial rotation occurs between the first and second vertebrae, at the atlanto-axial joint. Such motion is possible because of the lack of an intervertebral disc and the shape of the articular facets. The limitation of axial rotation, essential because the spinal cord and vertebral arteries cross this joint, is achieved with ligamentous structures, of which the left and right alar ligaments are primary. When one of the alar ligaments was cut in previous tests of human cadaveric spine (n = 10), the axial rotation to both sides significantly increased. This result does not agree with the long-held hypothesis that axial rotation is limited only by the alar on the side opposite rotation. The purpose of this work was to develop a model of the alar ligaments in axial rotation that is consistent with recent experimental observations. This model predicts that both alars must be intact to limit axial rotation; if one alar is injured, the normal mechanism becomes nonfunctional. The model also predicts the observation that a significant percentage of rotation at the atlanto-axial joint occurs freely, without ligamentous resistance. A physical and a mathematical description of the model is presented. Cadaveric experimental data are demonstrated to support the model.

Biomechanical Phenomena↗