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ABSTRACT: Prior to implantation, spinal implants are subjected to rigorous testing to ensure safety and efficacy. A full battery of tests for the devices may include many steps ranging from biocompatibility tests to in vivo animal studies. This paper describes some of the essential tests from a mechanical engineering perspective (e.g., motion, load sharing, bench type tests, and finite element model analyses). These protocols reflect the research experience of the past decade or so.
Neurology India 01/2006; 53(4):399-407. · 0.96 Impact Factor
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ABSTRACT: Forty lumbar pedicles and pedicle screws in four cadavers were used to identify the anterior and posterior portions of the lumbar pedicle cortex by roentgenograms in order to evaluate the penetration of the pedicle cortex by pedicle screws intraoperatively. Firstly, the transverse pedicle angles were measured on roentgenograms. Three roentgenograms were taken on each pedicle in three different directions: (1). medial to the pedicle axis; (2). pedicle axis; (3). lateral to the pedicle axis. They revealed that the anterior portion of the lateral pedicle cortex was demonstrated by the pedicle lateral outline on the roentgenogram medial to the pedicle axis, and the posterior portion by the pedicle lateral outline on the roentgenogram lateral to the pedicle axis. Wire markers were used to confirm these data. Finally, anterior and/or posterior penetrations on the lateral pedicle cortex in pedicle screw fixation were studied by roentgenograms in these cadavers and showed that anterior penetration of lateral cortex was demonstrated by the view medial to the pedicle axis, and posterior penetration by the view lateral to the pedicle axis. It is concluded that projections medical and lateral to the pedicle axis are necessary to identify lateral screw penetration intraoperatively when X-ray checking is used.
Surgical and Radiologic Anatomy 01/2003; 24(5):313-8. · 1.06 Impact Factor
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ABSTRACT: This study clarifies the pattern of fracture lines and facilitates diagnosis of transverse sacral fracture on plain radiographic images. Eight cadaveric sacra were used in this study. A U-shaped transverse sacral fracture at the S2-S3 level was created in all specimens. The fracture line was marked by painting with radio-opaque material and solder metal wires. The following radiographic views were taken: anteroposterior, lateral, AP with 35 degrees cephalad orientation, and inlet view. A double shadow in the upper sacral area can be identified in the plain AP view. As a consequence of the fracture, there are changes in the orientation of the planes of the foramina from the coronal to, more or less, axial plane. Anteroposterior with 35 degrees cephalad orientation radiographs provide good assessment for evaluation of the transverse sacral fracture.
Orthopedics 12/2001; 24(11):1071-4. · 2.66 Impact Factor
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ABSTRACT: This retrospective clinical study assessed proximal tibial fractures managed with the Tosic external fixator. Nineteen patients with 21 proximal tibial fractures treated with the Tosic external fixator between July 1997 and October 1998 comprised the study population. Eleven fractures were graded as 41A2, 3 fractures as 41 A3, 4 fractures as 41C1, and 3 fractures as 41 C2. Fourteen fractures were closed, and 7 fractures were open. Average time to healing was 1 7 weeks. No revision of fixation was needed. There were five cases of pin tract infection. Average range of knee motion was 2 degrees-135 degrees. These results indicate the Tosic external fixator is an efficient and simple way to treat proximal tibial metaphyseal fractures.
Orthopedics 07/2001; 24(6):581-4. · 2.66 Impact Factor
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ABSTRACT: A visual three-dimensional image of the first sacral vertebra was constructed using computer software to predict the sites of strong density for better screw purchase of upper sacrum. Forty dry sacrum specimens were scanned in the prone position. An axial section, 10 mm below the S1 end plate, was selected for determining density at the region of interest. All images were stored on an optic disc and studied using the NIH Image 1.61 program. Plot analysis assessed the bone density in different regions. Also, three-dimensional pictures of the different screw paths and the related bone density in the upper sacrum were analyzed. Bone density in the anterolateral part of S1 was 115.1 +/- 10.4 pixel. Bone density for males (-99.7 +/- 11.3) was greater than for females (-131.4 +/- 9.6). Bone density in the anterolateral alar region was -108 +/- 10.6. The bone density for males (-95.6 +/- 9.8) and females (121.4 +/- 11.7) was more than the body region. Bone density in the middle anterior cortex of the ala was 759.8 +/- 11.6. Bone density for males (878.2 +/- 10.7) was greater than for females (637.6 +/- 11.9). Using surface plot, the midanterior cortex of the ala had high cortical density compared with other areas. The midanterior cortex of the sacral ala had the highest bone density. Sacral screw purchase in the midanterior cortex provides better mechanical fixation.
Orthopedics 06/2001; 24(5):475-7. · 2.66 Impact Factor
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ABSTRACT: The intramedullary fibular graft was used in four patients for tibiotalocalcaneal fusion. There were three men and one woman. The average age was 49.7 years (range, 35-73 years). The initial injuries were three pilon fractures and one ankle fracture. Tibiotalocalneal arthrodesis was performed as a salvage procedure for patients with significant posttraumatic arthritis of the ankle, concomitant subtalar arthritis, and severe osteopenia. The average followup was 28 months (range, 24-31 months). All the patients had successful arthrodesis and were satisfied with the outcome results. The average preoperative American Orthopaedic Foot And Ankle Society ankle-hindfoot score for the whole group was 49.5 (range, 44-54) and improved postoperatively to 78.5 (range, 71-81). Three patients had a good score and one patient had a fair score. There was no postoperative infection or fracture of the graft.
Clinical Orthopaedics and Related Research 05/2001; · 2.53 Impact Factor
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ABSTRACT: A common complication of surgical management of fractures of the lower radius involves hardware penetration of the articular surface. If neglected, this complication will lead to wrist joint degeneration. The authors of this study describe a plain roentgenographic angled view of the wrist that provides visualization of the distal radial articular surface to detect any hardware penetration. This view can also be used during surgery by means of an image intensifier.
American journal of orthopedics (Belle Mead, N.J.) 04/2001; 30(3):244-5.
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ABSTRACT: This is an anatomic and radiologic study on the lateral mass of the C2 vertebra.
To define the location of the pedicle and pars interarticularis in the C2 vertebra.
Transpedicular screw fixation of the C2 has been addressed in the literature. However, the use of the anatomic terminology of the pedicle or pars interarticularis (isthmus) in C2 is confusing in most of orthopaedic and neurosurgical literature since C2 is considered a transitional vertebra.
Twenty dry C2 vertebrae were obtained for observation of the external anatomy of the C2 from superior, lateral, and inferior views. Six C2 vertebrae were harvested from cadavers and sectioned in the sagittal, horizontal, and coronal planes to observe the internal structures of the lateral mass using high resolution radiographs.
Based on observation, the pedicle of the C2 vertebra is defined as the portion beneath the superior facet and anteromedial to the transverse foramen. The pars interarticularis or isthmus is defined as the narrower portion between the superior and inferior facets. No remarkable difference in bone density and trabecular bone orientation between the pedicle and pars interarticularis was noted.
It is still more appropriate to call this procedure "transpedicular screw fixation" in the C2 to avoid confusion, although this technique requires placing a screw from the posterior aspect of the inferior articular process through the isthmus and pedicle into the vertebral body.
Spine 03/2001; 26(4):E34-7. · 2.08 Impact Factor
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ABSTRACT: Sixteen embalmed cadavers were dissected to determine the location of the lumbar nerve root and sympathetic trunk with reference to the superior border of transverse process. In the posterolateral lumbar disk region, a safe zone was found between the anterior limit of the lumbar nerve and the posterior limit of the sympathetic trunk. It has a transverse dimension of 22 mm at the T12-L1 disk region and 25 mm at the L4-L5 disk region. The only exception to this was the genitofemoral nerve running close to the lateral margin of the L2-L3 disk. The study provides an understanding of the posterolateral orientation of the lumbar nerves and sympathetic trunk.
Orthopedics 02/2001; 24(1):56-8. · 2.66 Impact Factor
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ABSTRACT: Using axial computed tomography (CT), we measured pedicle width, pedicle axis length, pedicle transverse angle, and distance between screw entry point and vertebrae midline in the cervical spines (C3-C7) of 40 patients. All measurements were greater in men than in women, and we noted significant sex differences at most levels of pedicle inner and outer widths (P < or = .05 or P < or = .01). Mean pedicle inner and outer widths for all levels and all patients ranged from 2.3 to 3.0 mm and from 5.0 to 6.0 mm, respectively. Mean distances between screw entry point and vertebrae midline ranged from 22.2 to 23.7 mm. Results of this study-along with axial CT measurements of individual pedicle diameter, pedicle transverse angle, and screw entry point-would be useful when considering and performing transpedicular screw fixation in the cervical spine.
American journal of orthopedics (Belle Mead, N.J.) 02/2001; 30(1):59-61.
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ABSTRACT: This retrospective study evaluated the diagnostic value of computed tomography in patients with sacroiliac pain. Computed tomography scans of the sacroiliac joints of 62 patients with sacroiliac joint pain were reviewed. The criteria to include the patient in the current study were pain relief after a local injection in the sacroiliac joint under computed tomography guidance, a physical examination consistent with a sacroiliac origin of the pain, and negative magnetic resonance imaging of the lumbar spine. A control group consisted of 50 patients of matched age who had computed tomography scans of the pelvis for a reason other than pelvic or back pain. Computed tomography scans showed one or more findings in 57.5% and 31% of the sacroiliac joints in the symptomatic and the control groups, respectively. The computed tomography scans were negative in 37 (42.5%) symptomatic sacroiliac joints with a positive sacroiliac joint injection test. The sensitivity of computed tomography was 57.5 % and its specificity was 69%. The finding of the current study suggests limited diagnostic value of computed tomography in sacroiliac joint disease because of its low sensitivity and specificity. With clinical suspicion of a sacroiliac origin of pain, intraarticular injection is currently the only means to confirm that diagnosis.
Clinical Orthopaedics and Related Research 02/2001; · 2.53 Impact Factor
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ABSTRACT: A technique to aid the reconstruction of the ulna in case of comminuted Monteggia fracture-dislocation is presented. This involves reducing the proximal radioulnar joint and temporarily transfixing the radial head to the ulna by 1 or 2 Kirschner (K) wires to establish the ulnar length. Once ulnar length has been defined, reconstruction of the comminuted ulna fracture is simplified. The radioulnar K-wires are then removed and the radioulnohumeral joint is tested for stability. This technique has been used in 6 cases of type-1 Monteggia fracture-dislocation with no subsequent malunion of the ulnar fracture or redislocation' of the radial head. After an average of 13 months follow-up, all patients had nearly full range of motion of the elbow joint.
American journal of orthopedics (Belle Mead, N.J.) 01/2001; 29(12):960-3.
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ABSTRACT: Fifty-eight patients with 60 talar fractures were retrospectively reviewed. There were 39 men and 19 women. The age average was 32 (range, 14-74). Eighty six percent of the patients had multiple injuries. The most common mechanism of injury was a motor vehicle accident. Twenty-seven (45%) of the fractures were neck, 22 (36.7%) process, and 11 (18.3%) body. Forty-eight fractures had operative treatment and 12 had non-operative management. The average follow-up period was 30 months (range, 24-65). Thirty-two fractures (53.3%) developed subtalar arthritis. Two patients had subsequent subtalar fusion. Fifteen fractures (25%) developed ankle arthritis. None of these patients required ankle fusion. Fractures of the body of the talus were associated with the highest incidence of degenerative joint disease of both the subtalar and ankle joints. Ten fractures (16.6%) developed avascular necrosis (AVN), only one of which had subsequent slight collapse. Avascular necrosis occurred mostly after Hawkins Type 3 and 2 fractures of the talar neck. Three rating scores were used in this series to assess the outcome: the American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score, Maryland Foot Score, and Hawkins Evaluation Criteria. The outcome was different with every rating system. However, the outcome with AOFAS Ankle-Hindfoot Score and Hawkins Evaluation Criteria were almost equivalent. Assessment with the three rating scores showed that the process fractures had the best results followed by the neck and then the body fractures.
The Foot and Ankle Online Journal 01/2001; 21(12):1023-9. · 1.22 Impact Factor
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ABSTRACT: Dissection and measurements of the first 2 sacral nerve roots with regard to the commonly used entrance points for S1 and S2 pedicle screw placement were performed to determine the location of the first 2 sacral nerve roots in relation to the pedicle screw entrance points in the upper 2 sacral vertebrae. The sacral nerve roots, dural sac, and pedicles were exposed after laminectomy. The mean distance from the reference point to the adjacent nerve roots superiorly and inferiorly at the S2 pedicle level was smaller than those at the S1 pedicle level. The medial angle of the sacral nerve roots progressively decreased from L5 to S3. The nerve root passing through the next foramen formed an immediate medial relation to the sacral pedicle rather than the dural sac. Pedicle screw placement in the first 2 sacral vertebral pedicles has been recommended for lumbosacral fusion and internal fixation of sacral fractures. No anatomic study is available regarding the location of the sacral nerve roots relative to the entrance points of sacral pedicle screw placement. Violation of the sacral canal and foramina by a sacral pedicle screw may injure the sacral nerve roots, especially at the level of the S2 pedicle.
American journal of orthopedics (Belle Mead, N.J.) 12/2000; 29(11):873-7.
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The Journal of trauma 11/2000; 49(4):758-9. · 2.48 Impact Factor
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ABSTRACT: Twelve cadavers were dissected for the study of the cervicothoracic junction. The results showed that the mean heights and widths of the ganglia tend to decrease from the C-6 to T-4 nerve. The mean distances between the dura and the ganglion and the mean spinal nerve angles increased consistently from C-5 to T-4. The mean distances from the spinal nerves to the superior and inferior pedicles ranged 0.8-2.3 mm. It was noted that the mean value was significantly greater for the distance from the spinal nerve to the superior pedicle than that to the inferior pedicle for the spinal nerves C5-7 (P< or =.05). This information, in conjunction with imaging studies, may minimize spinal nerve injury during posterior pedicle screw fixation in the cervicothoracic spine.
American journal of orthopedics (Belle Mead, N.J.) 11/2000; 29(10):779-81.
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ABSTRACT: Thirty upper limbs from skeletally mature embalmed cadavers were studied to determine the anatomic reliability of the posterior interosseous nerve as a donor nerve graft. The posterior interosseous nerve branches 0.43 +/- 0.52 cm from the distal edge of the superficial head of the supinator and 8 +/- 1.6 cm from the lateral epicondyle form a common leash. There are 6 branches, which are arranged from the ulnar to the radial side at their origin from this leash. The first and second branches supply the extensor digitorum communis, the third branch supplies the extensor carpi ulnaris, the fourth branch supplies the extensor digiti minimi, and the fifth branch arises from the undersurface of the common leash and divides into 2 sub-branches (medial and lateral) 10.1 +/- 3.2 cm distal to the lateral epicondyle and 12.8 +/- 2.2 cm proximal to Lister's tubercle. These 2 sub-branches make an inverted V shape around the extensor pollicis longus. The medial branch supplies the extensor pollicis longus and extensor indicis proprius. The lateral branch supplies the extensor pollicis longus and extensor pollicis brevis and ends at the wrist capsule. At a mean distance of 8.1 +/- 1.2 cm proximal to Lister's tubercle the lateral sub-branch gives off its last muscular branch to the extensor pollicis longus and becomes a pure sensory terminus. As the terminal part of the lateral sub-branch approaches the wrist capsule it expands at a mean distance of 1.9 +/- 0.5 cm proximal to Lister's tubercle. The sixth branch arises from the radial side of the common leash and divides into 3 sub-branches. The first sub-branch supplies the abductor pollicis longus and extensor pollicis brevis, the second supplies the abductor pollicis longus, and the third supplies the superficial head of the supinator. This study showed that the mean length obtainable for harvesting the lateral sub-branch of the fifth branch of the posterior interosseous nerve is 6.2 +/- 0.7 cm, which represents the length of the nerve between the last muscular branch to the extensor pollicis longus to the point at which the nerve expands.
The Journal Of Hand Surgery 10/2000; 25(5):930-5. · 1.35 Impact Factor
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ABSTRACT: An anatomic study of the posterior interosseous nerve (PIN) in 20 cadaver upper limbs was performed to measure different segments of the PIN and its relationship with radius and ulna (results given as mean +/- SD). The length of the PIN from radial head to the arcade of Frohse (AF) was 26.5 +/- 1.6 mm and 25.3 +/- 1.1 mm in male and female cadavers, respectively. The length of the PIN from radial head to the PIN exit point from the supinator was 66.7 +/- 4.7 mm and 64.0 +/- 2.5 mm in male and female cadavers, respectively. The overall length of the PIN underlying the supinator muscle was 44.0 +/- 0.5 mm and 37.0 +/- 0.5 mm in male and female cadavers, respectively. The distance between the PIN exit point from the supinator and the radial margin of the radius was 15.0 +/- 0.9 mm and 14.5 +/- 0.9 mm in male and female cadavers, respectively. The distance between the PIN exit point from the supinator and ulnar margin of ulna was 18.2 +/- 0.6 mm and 17.9 +/- 0.7 mm in male and female cadavers, respectively. In 70% (n = 14) of the cadavers, the AF was tendinous and in 30% (n = 6), it was membranous. The length, width, and thickness of AF in males and females, respectively, were 18.6 +/- 1.2 mm / 18.5 +/- 1.3 mm; 2.8 +/- 0.4 mm / 2.5 +/- 0.4 mm; and, 0.8 +/- 0.08 mm / 0.7 +/- 0.07 mm. In all specimens, the PIN exited through the distal supinator muscle by penetrating the muscle. The PIN exit point from the supinator belly was about 11-19 mm from distal border of the latter. The mean distances between PIN exit point from the supinator and the origin of the extensor digitorum communis, abductor pollicis longus, and extensor pollicis longus branches were 7.5 mm, 31 mm, and 58 mm, respectively.
American journal of orthopedics (Belle Mead, N.J.) 10/2000; 29(9):702-4.
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ABSTRACT: The charts and radiographs of 118 patients with 126 intraarticular fractures of the calcaneus were reviewed retrospectively. Eleven of 126 (8.7%) calcaneal fractures had injuries consisting of intraarticular calcaneal fracture, lateral subluxation or dislocation of the posterior facet, fracture extension into the calcaneocuboid joint, peroneal tendon subluxation, subluxation of the talus in the ankle mortise, and complete disruption of the anterior talofibular and calcaneal fibular ligaments or fracture of the lateral malleolus. There were six women and five men. The average age was 40 years (range, 17-65 years). The mechanism of injury was a motor vehicle accident in eight and a fall from a height in three. According to the classification of Sanders et al eight fractures were Type II, one was Type III, and two were Type IV. Followup at an average of 26 months (range, 14-38 months) showed that eight of 11 patients (72.7%) had either good or excellent results. When lateral subluxation of the posterior facet of the calcaneus is identified with a preoperative computed tomography scan, operative management is indicated, and the surgeon should search for associated injuries that should be addressed at the time of surgery.
Clinical Orthopaedics and Related Research 09/2000; · 2.53 Impact Factor
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ABSTRACT: An anatomic study.
To evaluate the effect of displacement of the fractured posterior facet in tongue fracture of the calcaneus on the congruity of the subtalar joint.
Eleven feet were used in this study. Seven females and four males with age range from 59 to 78. The specimens were dissected from both the lateral and the medial aspects of the calcaneus to expose these surfaces. A primary fracture line was created first, then a secondary line was engineered to simulate tongue fracture. Displacement of the superio-lateral fragment was done with 5-mm increment. Radiography was performed and the graphs were scanned and studied on specific computer software to explore the effects of displacement on joint congruity.
The anterior end of the fragment of the tongue fracture, when displaced, not only is depressed but also rotated in the sagittal plane in a downward or planterward direction. The articular surface of the posterior facet of the calcaneus and the inferior facet of the talus are maintained in congruence with each other despite the varying degree of displacement and rotation.
Congruity of the subtalar joint in tongue fractures is maintained despite different degrees of displacement. This study explains why the non-surgical treatment outcome is comparable to that of the operative treatment in tongue fractures of calcaneus. It also explains why tongue fractures have a good outcome with closed reduction.
The Foot and Ankle Online Journal 09/2000; 21(8):665-8. · 1.22 Impact Factor
