Biomedical subjects

J J Crisco

Publications and source records attributed to J J Crisco.

At least 19 recordsLinked to original sources

PubMed2001

Mechanical properties of the human cervical spine as shown by three-dimensional load-displacement curves.

STUDY DESIGN: The mechanical properties of multilevel human cervical spines were investigated by applying pure rotational moments to each specimen and measuring multidirectional intervertebral motions. OBJECTIVES: To document intervertebral main and coupled motions of the cervical spine in the form of load-displacement curves. SUMMARY OF BACKGROUND DATA: Although a number of in vivo and in vitro studies have attempted to delineate normal movement patterns of the cervical spine, none has explored the complexity of the whole cervical spine as a three-dimensional structure. METHODS: Sixteen human cadaveric specimens (C0-C7) were used for this study. Pure rotational moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied using a specially designed loading fixture. The resulting intervertebral motions were recorded using stereophotogrammetry and depicted as a series of load-displacement curves. RESULTS: The resulting load-displacement curves were found to be nonlinear, and both rotation and translation motions were coupled with main motions. With flexion-extension moment loading, the greatest degree of flexion occurred at C1-C2 (12.3 degrees), whereas the greatest degree of extension was observed at C0-C1 (20.2 degrees). With axial moment loading, rotation at C1-C2 was the largest recorded (56.7 degrees). With lateral bending moments, the average range of motion for all vertebral levels was 7.9 degrees. CONCLUSIONS: The findings of the present study are relevant to the clinical practice of examining motions of the cervical spine in three dimensions and to the understanding of spinal trauma and degenerative diseases.

Analysis of Variance↗

PubMed2001

In vivo kinematic behavior of the radio-capitate joint during wrist flexion-extension and radio-ulnar deviation.

The capitate is often considered the "keystone" of the carpus, not simply because of its central and prominent position in the wrist, but also because of its mechanical interactions with neighboring bones. The purpose of this study was to determine in vivo three-dimensional capitate kinematics. Twenty uninjured wrists were investigated using a recently developed, non-invasive markerless bone registration (MBR) technique. Surface contours of the capitate, third metacarpal and radius were extracted from computed tomography images of seven wrist positions and the three-dimensional motions of the capitate and third metacarpal were calculated with respect to the radius in wrist flexion-extension and radio-ulnar deviation. We found that in vivo capitate motion does not simply occur about a single pivot point like a universal joint, as demonstrated by non-intersecting rotation axes for different capitate motions. The distance between flexion and ulnar deviation axes was 3.9+/-2.0 mm, and the distance between extension and ulnar deviation axes was 3.9+/-1.4 mm. Furthermore, capitate axes for males tended to be located more distally than axes for females. However, we believe that this result is related to subject size and not to gender. We also found that there is minimal relative motion between the capitate and third metacarpal during these in vivo wrist motions. These findings demonstrate the complexity of capitate kinematics, as well as the different mechanisms through which wrist flexion, extension, radial deviation and ulnar deviation occur.

Adult↗

PubMed2001

Advances in the in vivo measurement of normal and abnormal carpal kinematics.

This article presents the development of an in vivo, three-dimensional methodology using markerless bone registration for examining the normal and abnormal kinematics of the wrist carpal bones. The resulting descriptions of three-dimensional kinematics from healthy patients and patients with documented unilateral scapholunate interosseous ligament injuries are briefly presented.

Biomechanical Phenomena↗

PubMed2000

In vivo scaphoid, lunate, and capitate kinematics in flexion and in extension.

Carpal kinematics have been previously limited to in vitro models with cadaveric specimens. Using a newly developed markerless bone registration algorithm, we noninvasively studied the in vivo kinematics of the capitate, scaphoid, and lunate during wrist extension and flexion in both wrists of 5 men and 5 women. Computed tomography volume images were acquired in neutral and in 2 positions in both extension and flexion. The 3-dimensional kinematics of the capitate, scaphoid, and lunate relative to the radius were the determined. Scaphoid and lunate rotations differed for flexion and extension but were found to vary linearly with capitate rotation. In flexion the scaphoid contributed 73% of capitate motion and the lunate contributed 46%. In extension the scaphoid contributed 99% of capitate motion and the lunate contributed 68%. Contributions of the scaphoid and lunate to wrist extension were 15% greater than values reported in previous in vitro studies, while scaphoid and lunate contributions to wrist flexion were more similar to previous studies. The findings support a relative "engagement" of the scaphoid, capitate, and lunate during wrist extension. The only difference between male and female kinematics was a more distal location of the rotation axes; we believe this was due to a difference in carpal bone size, not gender. This study reports the 3-dimensional in vivo measurement of carpal motion using a noninvasive technology. This technique may prove useful in the study of more complex motions of the hand and wrist and of the abnormal kinematics that occur following ligamentous injury.

Adult↗

PubMed2000

Kinematic accuracy of three surface registration methods in a three-dimensional wrist bone study.

The use of registration techniques to determine motion transformations noninvasively has become more widespread with the increased availability of the necessary software. In this study, three surface registration techniques were used to generate carpal bone kinematic results from a single cadaveric wrist specimen. Surface contours were extracted from specimen computed tomography volume images of the forearm, carpal, and metacarpal bones in four arbitrary positions. Kinematic results from each of three registration techniques were compared with results derived from multiple spherical markers fixed to the specimen. Kinematic accuracy was found to depend on the registration method and bone size and shape. In general, rotation errors of the capitate and scaphoid were less than 0.5 deg for all three techniques. Rotation errors for the other bones were generally less than 2 deg, although error for the trapezoid was greater than 2 deg in one technique. Translation errors of the bones were generally less than 1 mm, although errors of the trapezoid and trapezium were greater than 1 mm for two techniques. Tradeoffs existed in each registration method between image processing time and overall kinematic accuracy. Markerless bone registration (MBR) can provide accurate measurements of carpal kinematics and can be used to study the noninvasive, three-dimensional in vivo kinematics of the wrist and other skeletal joints.

Aged↗

PubMed2000

The effect of tubularization on the mechanical properties of patellar tendon grafts.

To determine the effect of tubularization on the prefailure mechanical properties of bone-patellar tendon-bone autografts used for anterior cruciate ligament repair, 10 bovine bone-patellar tendon-bone grafts were tested in tension before and after tubularization with running suture. The testing protocol involved a 5-N preload, 10 preconditioning cycles to 200 N, and a final test cycle to 950 N at 1000 N/sec. Five of the grafts were tested first as harvested (flat) and then again following tubularization. The remaining five grafts were tubularized prior to the initial testing, and final testing was done with the suture removed. Raw testing data were reduced to determine the amount of stretching associated with preconditioning, as well as laxity and stiffness of the preconditioned grafts. Tubularized grafts stretched significantly more than flat grafts during preconditioning: 3.5 times as much after the first preconditioning cycle (3.8+/-1.9 mm versus 1.1+/-0.78 mm) and 3.1 times as much after 10 cycles (5.0+/-2.1 mm versus 1.6+/-0.9 mm). There was no statistically significant difference in the stiffnesses of the tubularized and flat grafts, nor did tubularization have an effect on graft laxity. Interestingly, there was a slight increase in laxity the second time each graft was tested, regardless of whether the graft was flat or tubularized when it was first tested. These results highlight the importance of preconditioning patellar tendon grafts before fixation, especially those that have been tubularized.

Animals↗

PubMed1999

Noninvasive technique for measuring in vivo three-dimensional carpal bone kinematics.

Our present knowledge of the three-dimensional kinematic behavior of skeletal joints has been largely acquired with cadaveric models and use of invasive monitoring. In the wrist, the small size and complex motion of the carpal bones present a difficult challenge for implanted internal or external marker systems. This paper describes a technique for quantifying the three-dimensional kinematics of the wrist and carpal bones in vivo using noninvasive computed tomographic imaging. An error analysis employing a cadaveric specimen suggests that noninvasive carpal kinematics can be measured with an accuracy within 2 degrees of rotation and 1 mm of translation along a helical axis of motion. The in vivo application of this technique is illustrated with a single normal individual. Potential applications include the quantification of normal wrist motion, analysis of pathomechanics, and evaluation of surgical intervention. The technique is also applicable to other joints and imaging modalities.

Anatomy, Cross-Sectional↗

PubMed1998

Efficient calculation of mass moments of inertia for segmented homogeneous three-dimensional objects.

The equations for the volume, centroid, and mass moments of inertia of a three-dimensional object are derived using Green's theorem. The object is assumed to be homogeneous and described as a stack of two-dimensional cross-sections. Given these assumptions, our approach using Green's theorem dramatically decreases data manipulation and computation as compared to the classical mass element summation technique employed for three-dimensional discrete objects. Although numerous factors influence accuracy, we chose to evaluate two representative objects in two orientations to determine the influence of the number of two-dimensional cross-sections on the accuracy of the calculations. For these shapes, 15 cross-sections per object were required to achieve relative error below 1%.

Biomechanical Phenomena↗

PubMed1998

Stress wave velocities in bovine patellar tendon.

The velocity of longitudinal stress waves in an elastic body is given by the square root of the ratio of its elastic modulus to its density. In tendinous and ligamentous tissue, the elastic modulus increases with strain and with strain rate. Therefore, it was postulated that stress wave velocity would also increase with increasing strain and strain rate. The purpose of this study was to determine the velocity of stress waves in tendinous tissue as a function of strain and to compare these values to those predicted using the elastic modulus derived from quasi-static testing. Five bovine patellar tendons were harvested and potted as bone-tendon-bone specimens. Quasi-static mechanical properties were determined in tension at a deformation rate of 100 mm/s. Impact loading was employed to determine wave velocity at various strain levels, achieved by preloading the tendon. Following impact, there was a measurable delay in force transmission across the specimen and this delay decreased with increasing tendon strain. The wave velocities at tendon strains of 0.0075, 0.015, and 0.0225 were determined to be 260 +/- 52 m/s, 360 +/- 71 m/s, and 461 +/- 94 m/s, respectively. These velocities were significantly (p < 0.01) faster than those predicted using elastic moduli derived from the quasi-static tests by 52, 45, and 41 percent, respectively. This study has documented that stress wave velocity in patellar tendon increases with increasing strain and is underestimated with a modulus estimated from quasi-static testing.

Animals↗

PubMed1997

Complexity of the thoracic spine pedicle anatomy.

Transpedicular screw fixation provides rigid stabilization of the thoracolumbar spine. For accurate insertion of screws into the pedicles and to avoid pedicle cortex perforations, more precise knowledge of the anatomy of the pedicles is necessary. This study was designed to visualize graphically the surface anatomy and internal architecture of the pedicles of the thoracic spine. Fifteen vertebrae distributed equally among the upper, middle, and lower thoracic regions were used. For the purpose of mapping surface anatomy, each pedicle was cleaned, spray-painted white, and marked with more than 100 fine points. Using an optoelectronic digitizer, three-dimensional coordinates of the marked points and three additional points, representing a coordinate system, were digitized. A solid modeling computer program was used to create three-dimensional surface images of the pedicle. To obtain cross-sectional information, each pedicle was sectioned with a thin diamond-blade saw to obtain four slices, 1 mm in thickness and 0.5 mm apart. The pedicle slices were X-rayed and projected onto a digitizer. The internal and external contours were digitized and converted into graphs by a computer. The pedicles exhibited significant variability in their shape and orientation, not only from region to region within the thoracic spine, but also within the same region and even within the same pedicle. These variations are extremely significant in light of current techniques utilized in transpedicular screw fixation in the thoracic spine. Information documenting the three-dimensional complexity of pedicle anatomy should be valuable for surgeons and investigators interested in spinal instrumentation.

Adult↗

PubMed1997

A non-invasive method for studying in vivo carpal kinematics.

Seven uninjured and three injured patients were studied using midsagittal computed tomographic (CT) images at 10 degrees increments from full extension to full flexion. Each injured patient had a confirmed scapholunate ligament tear and normal radiographs. CT bony contours were digitized, and incremental motion determined using a specifically designed automated contour-matching algorithm. We expressed wrist motion as a ratio of lunocapitate (midcarpal) motion, and radiolunate (radiocarpal) motion. In normal wrists, motion occurred equally at the midcarpal and radiocarpal joints. In wrists with scapholunate ligament disruption, lunocapitate motion increased significantly throughout the arc of motion.

Adult↗

PubMed1997

The effects of exercise on ligamentous stiffness in the wrist.

The purpose of this study was to determine if exercise alters wrist joint laxity, as measured by the mechanical behavior of the scaphoid bone. The load-displacement behavior of the scaphoid was studied in the palmar-dorsal direction in both wrists of 7 healthy volunteers (n = 14) before and after 2 exercise protocols (grip and push-up). When compared to the rested values, both exercise protocols significantly increased the displacement at 40 N by 47% (grip) and by 34% (push-up). Accordingly, the stiffness decreased significantly by 36% (grip) and by 32% (push-up). Partial recovery was documented after 1 hour of rest and there were no differences between any of the groups after 24 hours of rest. The increase in laxity documented during these exercise protocols reduces the ligament loads at comparable wrist positions and may thereby reduce the likelihood of traumatic ligamentous injury during participation in strenuous activity or sports.

Adult↗

PubMed1997

Kinematics of the scaphoid shift test.

Twenty-five uninjured subjects (50 wrists) were examined clinically and fluoroscopically during performance of the scaphoid shift test. Wrists were placed into 3 groups on the basis of the degree of palpable carpal motion that occurred during the clinical examination. Kinematic parameters of rotation and displacement were calculated from digitized images of the carpals at rest and at maximum displacement. On clinical exam, 36% of normal individuals had positive findings on scaphoid shift test. Dorsal displacement of the scaphoid was not significantly associated with positive scaphoid shift test results in these subjects, while total displacement of the scaphoid (the sum of axial and dorsal displacement) was significantly associated with positive test results. The principle confounding factor appeared to be a high degree of displacement that occurred at the capitolunate joint in some individuals, termed a "midcarpal shift." The data demonstrate that despite a high prevalence of positive scaphoid shifts among uninjured individuals, the ability to accurately detect dorsal displacement of the scaphoid using the scaphoid shift test is limited. On the basis of their findings, the authors recommend that positive test results be confirmed fluoroscopically.

Adult↗

PubMed1997

The influence of baseball modulus and mass on head and chest impacts: a theoretical study.

Although not common, injuries that result in death do occur in youth baseball. Specifically, in the 5- to 14-year old age group a total of 68 deaths between 1973 and 1995 have been directly attributed to impacts from baseballs to the head and chest. The purpose of this work was to determine the effect of lowering ball modulus and ball mass on the likelihood of reducing impact injury. A theoretical model, based upon the assumption of ideal elastic behavior, was used to calculate the impact response of the head. At a constant ball velocity, lowering both modulus and mass had the greatest influence in decreasing peak head acceleration, Gadd Severity Index, and Head Injury Criterion. Independently lowering the modulus or the mass decreased the impact variables and the estimates of injury, but the decreases varied with the specific impact variable and injury criterion. To study the impact response of the ball and chest, an existing viscoelastic lumped-element model of the chest was used. Lowering ball modulus and mass had various effects, e.g., lowering ball modulus did not affect peak sternal displacement, but it did decrease peak sternal velocity. These theoretical models aid in illustrating that impact response depends upon ball modulus and mass, the physical properties of the target, and the specific impact variable studied. This theoretical model suggests that a softer and lighter than traditional baseball would be the most likely ball model to minimize impact injuries because this ball consistently reduced all impact response variables studied. Since impact injury criteria for youths are presently not validated, the degree to which impact injuries may be reduced remains uncertain.

Adolescent↗

PubMed1996

Effects of posture and structure on three-dimensional coupled rotations in the lumbar spine. A biomechanical analysis.

STUDY DESIGN: A biomechanical lumbar spine model was constructed to simulate three-dimensional spinal kinematics under the application of pure moments. Parametric analysis of the model allowed for the estimation of how much of the coupled motions could be predicted by the lumbar lordosis and the intrinsic mechanical properties of the spine. OBJECTIVES: To evaluate the relative effects of lordosis and intrinsic mechanical spine properties on the magnitude and direction of coupled rotations. SUMMARY OF BACKGROUND DATA: Clinical evidence suggests that abnormal coupled motion in the lumbar spine may be an indicator of low back disorders. METHODS: The biomechanical lumbar spine model consisted of five vertebrae separated by intervertebral joints that provided three rotational degrees of freedom. In vitro experimental data, obtained from nine fresh-frozen (L1-S1) cadaveric specimens, were used to establish the mechanical properties of the intervertebral joints. Two different submodels were considered in simulating the three-dimensional intervertebral rotations in response to the applied moments. In the first, it was assumed that the coupled motions were generated solely as a result of the vertebral orientation caused by lordosis. In the second, additional intrinsic motion coupling was assumed. RESULTS: Intervertebral coupling was partially predicted by lumbar lordosis; however, the inclusion of intrinsic mechanical coupling dramatically improved the simulation of the intervertebral rotations (root mean square error < 1 degree). Comparison of the results from the two models demonstrated that the lumbar lordosis and intrinsic mechanical properties of the spine had about an equal effect in predicting the coupling between axial rotation and lateral bending. In contrast, coupled flexion, associated with lateral bending, was almost fully accounted for by the presence of lumbar lordosis. CONCLUSIONS: The lumbar lordosis and intrinsic mechanical properties of the spine were equally important in predicting the magnitude and direction of the coupled rotations.

Adult↗

PubMed1996

Subfailure injury of the rabbit anterior cruciate ligament.

Ligamentous injuries range in severity from a simple sprain to a complete rupture. Although sprains occur more frequently than complete failures, only a few studies have investigated the phenomena of these subfailure injuries. The purpose of our study was to document the changes in the load-deformation curve until the failure point, after the ligament has been subjected to an 80% subfailure stretch. Thirteen paired fresh rabbit bone-anterior cruciate ligament-bone preparations were used. One of the pairs (control) was stretched until failure; the other (experimental) was first stretched to 80% of the failure deformation of the control and then stretched to failure. Comparisons were made between the load-deformation curves of the experimental and control specimens. The nonlinear load-deformation curves were characterized by eight parameters: failure load (Ffail), failure deformation (Dfail), energy until failure (Efail), deformations measured at 5, 10, 25, and 50% of the failure load (D5, D10, D25, and D50, respectively), and stiffness measured at 50% of the failure force (K50). There were no significant differences in the values for Ffail, Dfail, and Efail between the experimental and control ligaments (p > 0.33). In contrast, the deformation values were all larger for the experimental than the control ligaments (p > 0.01). The deformations D5, D10, D25, and D50 (mean +/- SD) for the control were 0.36 +/- 0.13, 0.49 +/- 0.23, 0.81 +/- 0.35, and 1.23 +/- 0.41 mm. The corresponding deformations for the experimental ligaments were, respectively, 209, 186, 153, and 130% of the control values. K50 was also greater for the experimental ligament (125.0 +/- 41.7 N/mm compared with 108.7 +/- 31.4 N/mm, p < 0.03). These findings indicate that even though the strength of the ligament did not change due to a subfailure injury, the shape of the load-displacement curve, especially at low loads, was significantly altered. Under the dynamic in vivo loading conditions of daily living, this may result in increased joint laxity, additional loads being applied to other joint structures, and, with time, to joint problems.

Animals↗

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↗