Comminuted extra-articular distal humerus fractures often result from high-energy trauma or low-e... more Comminuted extra-articular distal humerus fractures often result from high-energy trauma or low-energy trauma in the elderly. The comminution leads to instability of these fractures and surgical fixation is often required. For distal humerus fractures, dual plate fixation has been shown to be biomechanically superior to single plate fixa-tion. 1) Locking plates are more stable in axial loading than the nonlocking constructs. 2) The two categories of locking plates are fixed-angle and variable-angle locking plates. In a variable-angle construct, the screw can be locked into the corresponding hole within a cone with an angle of 1° to 15° (unidirectional) and an overall variable arc of 30°3) (Zimmer and Depuy Synthes). 4) In some fixation systems, there is a posterolateral plate with a distal phalange extending to the lateral side of the humerus. This allows lateral to medial screw placement. Contouring of this portion of the plate is also possible to create variability in the screw trajectory without altering its head relationship to the plate. Other available technology includes cutting a custom thread in the plate prior to screw insertion or us
Les cellules AF, les chondrocytes et les CDMO (crête iliaque et fémur) ont été isolées et cultivé... more Les cellules AF, les chondrocytes et les CDMO (crête iliaque et fémur) ont été isolées et cultivées en monocouche. Elles ont été traitées trois jours par rhBMP-2. Après trois jours, la teneur en protéoglycanes (sGAG) dans le milieu a été mesurée. Les résultats ont été normalisés ...
The purpose of this study was to determine whether or not surgical floor mats affect low back and... more The purpose of this study was to determine whether or not surgical floor mats affect low back and leg muscle activity during prolonged standing. The EMG activity was measured continuously using surface electrodes on the paraspinal muscles of the low back and on the anterior tibialis muscles; the subjects were normal and stood on two different surfaces. Six male subjects were each instructed to stand for two hours on a specially designed surgical floor mat and then, on a separate day, to stand for two hours on a linoleum-covered concrete surface. Six other subjects carried out the same procedure, but stood on the linoleum first. There was no difference in EMG activity obtained from the anterior tibialis muscles and paraspinal muscles of the low back when the subjects stood on the surgical mat, as compared with the linoleum-covered concrete.
In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle ... more In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle screw failure. This study used osteoporotic and nonosteoporotic vertebrae to determine the difference in fixation strength between pedicle screws inserted straight forward and pedicle screws inserted in an upward trajectory toward the superior end plate (i.e., end-plate screws). There is some evidence to suggest that end-plate screws have a strength advantage. The particular focus was on osteoporotic vertebrae. Thirty-three vertebrae (T10-L2) were harvested. The bone mineral density (BMD) was measured: 15 vertebrae were greater than 0.8 g/cm(2) and designated as nonosteoporotic (average BMD 1.146 ± 0.186 g/cm(2)) and 18 vertebrae were designated as osteoporotic (average BMD 0.643 ± 0.088 g/cm(2)). On one pedicle the screw was inserted straight forward and on the other pedicle the screw was inserted as an end-plate screw. The torque of insertion was measured (Proto 6106 torque screwdriver...
The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedic... more The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedicle screws inserted into the pedicles of upper thoracic vertebrae (T2 to T5). Seven fresh human spines were obtained. The bone mineral density was measured by dual-energy radiograph absorptiometry. The 4.5-mm and 5.5-mm diameter screws were inserted alternately in the right or left pedicle of each vertebra. The insertion torque and force (applied in the cephalic direction) to produce loosening of the screw were measured. The average bone mineral density for the seven thoracic spines was 0.710 g/cm(2). All of the vertebrae were classified as osteoporotic. The torque of insertion for the 5.5-mm diameter screws was significantly greater (59% greater on average) than that for the 4.5-mm diameter screws (p =. 001). Although the average force to loosening for the 5.5-mm diameter screws was higher than the average force to loosening for the 4.5-mm diameter screws (14%), the difference was not si...
The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedic... more The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedicle screws inserted into the pedicles of upper thoracic vertebrae (T2 to T5). Seven fresh human spines were obtained. The bone mineral density was measured by dual-energy radiograph absorptiometry. The 4.5-mm and 5.5-mm diameter screws were inserted alternately in the right or left pedicle of each vertebra. The insertion torque and force (applied in the cephalic direction) to produce loosening of the screw were measured. The average bone mineral density for the seven thoracic spines was 0.710 g/cm(2). All of the vertebrae were classified as osteoporotic. The torque of insertion for the 5.5-mm diameter screws was significantly greater (59% greater on average) than that for the 4.5-mm diameter screws (p =. 001). Although the average force to loosening for the 5.5-mm diameter screws was higher than the average force to loosening for the 4.5-mm diameter screws (14%), the difference was not si...
The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterio... more The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterior-posterior displacement of the talus was evaluated in eight fresh-frozen cadaveric ankle joints. With the distal tibia stabilized, loads of 150 N were applied to the talus in the anterior direction while the ankle was held in neutral. All tests were initially performed on intact specimens. Loads were reapplied after sequential sectioning of the peroneal tendons and superior peroneal retinaculum and then the anterior talofibular ligament. When compared with intact ankles, releasing the peroneal tendons caused an average increase of 15% displacement (0.90 mm, p < .05). Adding the release of the anterior talofibular ligament increased the anterior displacement an additional 16% (1.35 mm, p < .05) for a combined anterior laxity of 34% (2.25 mm, p < .05). The data suggest that the peroneal tendons along with the superior peroneal retinaculum provide static resistance to anterior tal...
The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterio... more The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterior-posterior displacement of the talus was evaluated in eight fresh-frozen cadaveric ankle joints. With the distal tibia stabilized, loads of 150 N were applied to the talus in the anterior direction while the ankle was held in neutral. All tests were initially performed on intact specimens. Loads were reapplied after sequential sectioning of the peroneal tendons and superior peroneal retinaculum and then the anterior talofibular ligament. When compared with intact ankles, releasing the peroneal tendons caused an average increase of 15% displacement (0.90 mm, p < .05). Adding the release of the anterior talofibular ligament increased the anterior displacement an additional 16% (1.35 mm, p < .05) for a combined anterior laxity of 34% (2.25 mm, p < .05). The data suggest that the peroneal tendons along with the superior peroneal retinaculum provide static resistance to anterior tal...
Biomechanical comparison of five different posterior cervicothoracic junction (C7-T1) fixation co... more Biomechanical comparison of five different posterior cervicothoracic junction (C7-T1) fixation constructs in a cadaveric model. To determine whether augmenting C7 lateral mass screws with spinous process wires or additional fixation in the C6 lateral mass can create constructs of similar normalized stiffness to that of C7 pedicle screws. Cervical pedicle screws are known to provide excellent fixation but are potentially dangerous and technically demanding to insert. Lateral mass screws are safer and easier to insert but have less pullout strength and must often be short at C7. Twelve cadaveric cervicothoracic specimens (C5-T2) were randomly assigned to one of three experiments: Experiment A (Part 1 and Part 2), Experiment B, and Experiment C (Part 1 and Part 2) (n = 4 each for each experiment). First, the intact specimens were biomechanically tested according to a seven-part loading protocol. The specimens were then destabilized, and then restabilized with the following constructs i...
A biomechanical study of an interspinous stabilization spinal implant (Coflex) was carried out us... more A biomechanical study of an interspinous stabilization spinal implant (Coflex) was carried out using eight human lumbar L4/L5 motion segments. Each motion segment was tested in compression, then flexion/extension, then lateral bending, and then axial rotation at five conditions: 1) intact; 2) partial destabilization (by cutting the supraspinous and interspinous ligaments, the ligamentum flavum, the facet capsules, and 50% of the inferior bony facet bilaterally); 3) stabilization with the Coflex device; 4) complete destabilization with total laminectomy; and 5) stabilization with pedicle screws and rods. The most important result is that the motion segment after destabilization and insertion of the Coflex device does not allow significantly more or less motion than the intact specimen in either flexion/extension or axial rotation. Thus the Coflex offers nonrigid fixation and can return a partially destabilized specimen back to the intact condition in terms of motion in flexion/extens...
Open methods for removal of femoral interlocking nails involve an incision (up to 10 cm) over the... more Open methods for removal of femoral interlocking nails involve an incision (up to 10 cm) over the trochanter to find the tip of the nail. The distal locking screws are some times difficult to palpate and an incision (up to about 5 cm) is often needed for exposure. Intra-operative fluoroscopy is often used as an adjunct technique to minimize the surgical wound. However, patients and surgeons are exposed to a radiation hazard. Sonography can provide a real-time and efficient alternative to fluoroscopy. Sonography of soft tissue has been established to identify a foreign body. A metallic implant has a hyperechoic image; therefore, we can identify the correct position of the screws preoperatively and intraoperatively. We have developed a technique using sonography and minimal incisions for the removal of a femoral interlocking nail. The proximal wound is 2.5 cm in length and the wound is 0.5 cm in length for each distal locking screw. The sonography can be used to minimize the length of...
Nutrition to the cells in the disc is partly dependent on fluid flowing out during the day and fl... more Nutrition to the cells in the disc is partly dependent on fluid flowing out during the day and flowing in during bed rest. In spaceflight there are little or no such diurnal changes, since the gravitational load is essentially zero. The questions we asked were: 1) How much fluid does the disc gain during the night and how quickly does the disc lose fluid during the following day? 2) Is it possible to carry out, in a reasonable amount of time, an exercise regimen on a spacecraft that would be rigorous enough to expel from the disc the equivalent amount of fluid lost during a normal day's activity? in five normal subjects, magnetic resonance imaging was used to measure the volume changes (and the corresponding fluid changes) in the lumbar intervertebral discs (L1/L2, L2/L3, L3/L4, L4/L5) before and after a night's bed rest and again at specific intervals during the course of the day while carrying out three different protocols: walking, carrying a backpack, and exercising in a...
The purpose of this prospective animal study was to evaluate the efficacy of a resorbable coral p... more The purpose of this prospective animal study was to evaluate the efficacy of a resorbable coral particulate to serve as a carrier with several doses of a bovine-derived osteoinductive bone protein mixture. A previously validated rabbit model for posterolateral intertransverse process lumbar spinal fusion was used. Posterolateral intertransverse process arthrodeses were performed at L5-L6 in 64 adult New Zealand white rabbits. The bone graft substitute evaluated consisted of a Biocoral/collagen composite with one of four doses (0, 100, 300, or 1,000 micrograms) of a bovine-derived osteoinductive bone protein extract (BP). Fusions were assessed at 5 weeks by manual palpation, radiography, histology, and biomechanical testing. Use of the Biocoral/collagen carrier without BP resulted in no solid fusions. Biocoral/collagen with 100 micrograms BP resulted in solid fusions in 31% (4 of 13) of the rabbits. Biocoral with 300 micrograms or 1,000 micrograms BP resulted in solid spinal fusion i...
Biomechanical testing of the pullout strengths of pedicle screws placed by two different techniqu... more Biomechanical testing of the pullout strengths of pedicle screws placed by two different techniques in adult human cadaveric cervical spines. To determine whether there is a significant difference in screw purchase of two commonly proposed methods of cervical pedicle screw insertion. Wiring techniques remain the gold standard for posterior cervical fixation. However, absent or deficient posterior elements may dictate the use of alternative fixation techniques. Cervical pedicle screws have been shown to have significantly higher pullout strength than lateral mass screws. Fifty fresh disarticulated human vertebrae (C3-C7) were evaluated with computed tomography for anatomic disease and pedicle morphometry. The right and left pedicles were randomly assigned to either a standard method or the Abumi insertion method. In the latter technique the cortex and cancellous bone of lateral mass are removed with a high-speed burr, which provides a direct view of the pedicle introitus. The pedicle...
Two separate experiments (A and B), each involving six human cadaveric torsos with intact rib cag... more Two separate experiments (A and B), each involving six human cadaveric torsos with intact rib cages and sternums, were done to determine the effect of two different sequences of surgical releases (at T8-T9) on thoracic spinal motion. Experiment A was designed to test the effects of three releases in sequence from anterior to posterior, analogous to a two-stage operative treatment with anterior and posterior releases. Experiment B, which involved three releases, was designed to determine 1) if unilateral posterior total facetectomy alone allowed a significant increase in motion and 2) if rib head resection without discectomy allowed a significant increase in motion. In the surgical treatment of thoracic spinal deformity, surgical release is often done to impart additional flexibility to the spine. Available releases include discectomy, rib head resection, and facetectomy. There is little work to date on the relative importance of the disc, rib head, and facet joint in the stability o...
In order to compare the difference between young and old intervertebral disc cells and their resp... more In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen I and collagen II gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen II gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen II gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen II as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.
In order to compare the difference between young and old intervertebral disc cells and their resp... more In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen I and collagen II gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen II gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen II gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen II as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.
Comminuted extra-articular distal humerus fractures often result from high-energy trauma or low-e... more Comminuted extra-articular distal humerus fractures often result from high-energy trauma or low-energy trauma in the elderly. The comminution leads to instability of these fractures and surgical fixation is often required. For distal humerus fractures, dual plate fixation has been shown to be biomechanically superior to single plate fixa-tion. 1) Locking plates are more stable in axial loading than the nonlocking constructs. 2) The two categories of locking plates are fixed-angle and variable-angle locking plates. In a variable-angle construct, the screw can be locked into the corresponding hole within a cone with an angle of 1° to 15° (unidirectional) and an overall variable arc of 30°3) (Zimmer and Depuy Synthes). 4) In some fixation systems, there is a posterolateral plate with a distal phalange extending to the lateral side of the humerus. This allows lateral to medial screw placement. Contouring of this portion of the plate is also possible to create variability in the screw trajectory without altering its head relationship to the plate. Other available technology includes cutting a custom thread in the plate prior to screw insertion or us
Les cellules AF, les chondrocytes et les CDMO (crête iliaque et fémur) ont été isolées et cultivé... more Les cellules AF, les chondrocytes et les CDMO (crête iliaque et fémur) ont été isolées et cultivées en monocouche. Elles ont été traitées trois jours par rhBMP-2. Après trois jours, la teneur en protéoglycanes (sGAG) dans le milieu a été mesurée. Les résultats ont été normalisés ...
The purpose of this study was to determine whether or not surgical floor mats affect low back and... more The purpose of this study was to determine whether or not surgical floor mats affect low back and leg muscle activity during prolonged standing. The EMG activity was measured continuously using surface electrodes on the paraspinal muscles of the low back and on the anterior tibialis muscles; the subjects were normal and stood on two different surfaces. Six male subjects were each instructed to stand for two hours on a specially designed surgical floor mat and then, on a separate day, to stand for two hours on a linoleum-covered concrete surface. Six other subjects carried out the same procedure, but stood on the linoleum first. There was no difference in EMG activity obtained from the anterior tibialis muscles and paraspinal muscles of the low back when the subjects stood on the surgical mat, as compared with the linoleum-covered concrete.
In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle ... more In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle screw failure. This study used osteoporotic and nonosteoporotic vertebrae to determine the difference in fixation strength between pedicle screws inserted straight forward and pedicle screws inserted in an upward trajectory toward the superior end plate (i.e., end-plate screws). There is some evidence to suggest that end-plate screws have a strength advantage. The particular focus was on osteoporotic vertebrae. Thirty-three vertebrae (T10-L2) were harvested. The bone mineral density (BMD) was measured: 15 vertebrae were greater than 0.8 g/cm(2) and designated as nonosteoporotic (average BMD 1.146 ± 0.186 g/cm(2)) and 18 vertebrae were designated as osteoporotic (average BMD 0.643 ± 0.088 g/cm(2)). On one pedicle the screw was inserted straight forward and on the other pedicle the screw was inserted as an end-plate screw. The torque of insertion was measured (Proto 6106 torque screwdriver...
The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedic... more The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedicle screws inserted into the pedicles of upper thoracic vertebrae (T2 to T5). Seven fresh human spines were obtained. The bone mineral density was measured by dual-energy radiograph absorptiometry. The 4.5-mm and 5.5-mm diameter screws were inserted alternately in the right or left pedicle of each vertebra. The insertion torque and force (applied in the cephalic direction) to produce loosening of the screw were measured. The average bone mineral density for the seven thoracic spines was 0.710 g/cm(2). All of the vertebrae were classified as osteoporotic. The torque of insertion for the 5.5-mm diameter screws was significantly greater (59% greater on average) than that for the 4.5-mm diameter screws (p =. 001). Although the average force to loosening for the 5.5-mm diameter screws was higher than the average force to loosening for the 4.5-mm diameter screws (14%), the difference was not si...
The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedic... more The purpose of this study was to evaluate the difference between 4.5-mm and 5.5-mm diameter pedicle screws inserted into the pedicles of upper thoracic vertebrae (T2 to T5). Seven fresh human spines were obtained. The bone mineral density was measured by dual-energy radiograph absorptiometry. The 4.5-mm and 5.5-mm diameter screws were inserted alternately in the right or left pedicle of each vertebra. The insertion torque and force (applied in the cephalic direction) to produce loosening of the screw were measured. The average bone mineral density for the seven thoracic spines was 0.710 g/cm(2). All of the vertebrae were classified as osteoporotic. The torque of insertion for the 5.5-mm diameter screws was significantly greater (59% greater on average) than that for the 4.5-mm diameter screws (p =. 001). Although the average force to loosening for the 5.5-mm diameter screws was higher than the average force to loosening for the 4.5-mm diameter screws (14%), the difference was not si...
The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterio... more The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterior-posterior displacement of the talus was evaluated in eight fresh-frozen cadaveric ankle joints. With the distal tibia stabilized, loads of 150 N were applied to the talus in the anterior direction while the ankle was held in neutral. All tests were initially performed on intact specimens. Loads were reapplied after sequential sectioning of the peroneal tendons and superior peroneal retinaculum and then the anterior talofibular ligament. When compared with intact ankles, releasing the peroneal tendons caused an average increase of 15% displacement (0.90 mm, p < .05). Adding the release of the anterior talofibular ligament increased the anterior displacement an additional 16% (1.35 mm, p < .05) for a combined anterior laxity of 34% (2.25 mm, p < .05). The data suggest that the peroneal tendons along with the superior peroneal retinaculum provide static resistance to anterior tal...
The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterio... more The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterior-posterior displacement of the talus was evaluated in eight fresh-frozen cadaveric ankle joints. With the distal tibia stabilized, loads of 150 N were applied to the talus in the anterior direction while the ankle was held in neutral. All tests were initially performed on intact specimens. Loads were reapplied after sequential sectioning of the peroneal tendons and superior peroneal retinaculum and then the anterior talofibular ligament. When compared with intact ankles, releasing the peroneal tendons caused an average increase of 15% displacement (0.90 mm, p < .05). Adding the release of the anterior talofibular ligament increased the anterior displacement an additional 16% (1.35 mm, p < .05) for a combined anterior laxity of 34% (2.25 mm, p < .05). The data suggest that the peroneal tendons along with the superior peroneal retinaculum provide static resistance to anterior tal...
Biomechanical comparison of five different posterior cervicothoracic junction (C7-T1) fixation co... more Biomechanical comparison of five different posterior cervicothoracic junction (C7-T1) fixation constructs in a cadaveric model. To determine whether augmenting C7 lateral mass screws with spinous process wires or additional fixation in the C6 lateral mass can create constructs of similar normalized stiffness to that of C7 pedicle screws. Cervical pedicle screws are known to provide excellent fixation but are potentially dangerous and technically demanding to insert. Lateral mass screws are safer and easier to insert but have less pullout strength and must often be short at C7. Twelve cadaveric cervicothoracic specimens (C5-T2) were randomly assigned to one of three experiments: Experiment A (Part 1 and Part 2), Experiment B, and Experiment C (Part 1 and Part 2) (n = 4 each for each experiment). First, the intact specimens were biomechanically tested according to a seven-part loading protocol. The specimens were then destabilized, and then restabilized with the following constructs i...
A biomechanical study of an interspinous stabilization spinal implant (Coflex) was carried out us... more A biomechanical study of an interspinous stabilization spinal implant (Coflex) was carried out using eight human lumbar L4/L5 motion segments. Each motion segment was tested in compression, then flexion/extension, then lateral bending, and then axial rotation at five conditions: 1) intact; 2) partial destabilization (by cutting the supraspinous and interspinous ligaments, the ligamentum flavum, the facet capsules, and 50% of the inferior bony facet bilaterally); 3) stabilization with the Coflex device; 4) complete destabilization with total laminectomy; and 5) stabilization with pedicle screws and rods. The most important result is that the motion segment after destabilization and insertion of the Coflex device does not allow significantly more or less motion than the intact specimen in either flexion/extension or axial rotation. Thus the Coflex offers nonrigid fixation and can return a partially destabilized specimen back to the intact condition in terms of motion in flexion/extens...
Open methods for removal of femoral interlocking nails involve an incision (up to 10 cm) over the... more Open methods for removal of femoral interlocking nails involve an incision (up to 10 cm) over the trochanter to find the tip of the nail. The distal locking screws are some times difficult to palpate and an incision (up to about 5 cm) is often needed for exposure. Intra-operative fluoroscopy is often used as an adjunct technique to minimize the surgical wound. However, patients and surgeons are exposed to a radiation hazard. Sonography can provide a real-time and efficient alternative to fluoroscopy. Sonography of soft tissue has been established to identify a foreign body. A metallic implant has a hyperechoic image; therefore, we can identify the correct position of the screws preoperatively and intraoperatively. We have developed a technique using sonography and minimal incisions for the removal of a femoral interlocking nail. The proximal wound is 2.5 cm in length and the wound is 0.5 cm in length for each distal locking screw. The sonography can be used to minimize the length of...
Nutrition to the cells in the disc is partly dependent on fluid flowing out during the day and fl... more Nutrition to the cells in the disc is partly dependent on fluid flowing out during the day and flowing in during bed rest. In spaceflight there are little or no such diurnal changes, since the gravitational load is essentially zero. The questions we asked were: 1) How much fluid does the disc gain during the night and how quickly does the disc lose fluid during the following day? 2) Is it possible to carry out, in a reasonable amount of time, an exercise regimen on a spacecraft that would be rigorous enough to expel from the disc the equivalent amount of fluid lost during a normal day's activity? in five normal subjects, magnetic resonance imaging was used to measure the volume changes (and the corresponding fluid changes) in the lumbar intervertebral discs (L1/L2, L2/L3, L3/L4, L4/L5) before and after a night's bed rest and again at specific intervals during the course of the day while carrying out three different protocols: walking, carrying a backpack, and exercising in a...
The purpose of this prospective animal study was to evaluate the efficacy of a resorbable coral p... more The purpose of this prospective animal study was to evaluate the efficacy of a resorbable coral particulate to serve as a carrier with several doses of a bovine-derived osteoinductive bone protein mixture. A previously validated rabbit model for posterolateral intertransverse process lumbar spinal fusion was used. Posterolateral intertransverse process arthrodeses were performed at L5-L6 in 64 adult New Zealand white rabbits. The bone graft substitute evaluated consisted of a Biocoral/collagen composite with one of four doses (0, 100, 300, or 1,000 micrograms) of a bovine-derived osteoinductive bone protein extract (BP). Fusions were assessed at 5 weeks by manual palpation, radiography, histology, and biomechanical testing. Use of the Biocoral/collagen carrier without BP resulted in no solid fusions. Biocoral/collagen with 100 micrograms BP resulted in solid fusions in 31% (4 of 13) of the rabbits. Biocoral with 300 micrograms or 1,000 micrograms BP resulted in solid spinal fusion i...
Biomechanical testing of the pullout strengths of pedicle screws placed by two different techniqu... more Biomechanical testing of the pullout strengths of pedicle screws placed by two different techniques in adult human cadaveric cervical spines. To determine whether there is a significant difference in screw purchase of two commonly proposed methods of cervical pedicle screw insertion. Wiring techniques remain the gold standard for posterior cervical fixation. However, absent or deficient posterior elements may dictate the use of alternative fixation techniques. Cervical pedicle screws have been shown to have significantly higher pullout strength than lateral mass screws. Fifty fresh disarticulated human vertebrae (C3-C7) were evaluated with computed tomography for anatomic disease and pedicle morphometry. The right and left pedicles were randomly assigned to either a standard method or the Abumi insertion method. In the latter technique the cortex and cancellous bone of lateral mass are removed with a high-speed burr, which provides a direct view of the pedicle introitus. The pedicle...
Two separate experiments (A and B), each involving six human cadaveric torsos with intact rib cag... more Two separate experiments (A and B), each involving six human cadaveric torsos with intact rib cages and sternums, were done to determine the effect of two different sequences of surgical releases (at T8-T9) on thoracic spinal motion. Experiment A was designed to test the effects of three releases in sequence from anterior to posterior, analogous to a two-stage operative treatment with anterior and posterior releases. Experiment B, which involved three releases, was designed to determine 1) if unilateral posterior total facetectomy alone allowed a significant increase in motion and 2) if rib head resection without discectomy allowed a significant increase in motion. In the surgical treatment of thoracic spinal deformity, surgical release is often done to impart additional flexibility to the spine. Available releases include discectomy, rib head resection, and facetectomy. There is little work to date on the relative importance of the disc, rib head, and facet joint in the stability o...
In order to compare the difference between young and old intervertebral disc cells and their resp... more In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen I and collagen II gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen II gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen II gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen II as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.
In order to compare the difference between young and old intervertebral disc cells and their resp... more In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen I and collagen II gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen II gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen II gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen II as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.
Uploads
Papers by William Hutton