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A Biyani

Publications and source records attributed to A Biyani.

At least 19 recordsLinked to original sources
PubMed2005

Biomechanical comparison of lumbar spine with or without spina bifida occulta. A finite element analysis.

STUDY DESIGN: Biomechanical study using finite element model (FEM) of lumbar spine. OBJECTIVES: Very high coincidence of spina bifida occulta (SBO) has been reported more than in 60% of lumbar spondylolysis. The altered biomechanics due to SBO is one considerable factor for this coincidence. Thus, in this study, the biomechanical changes in the lumbar spine due to the presence of SBO were evaluated. SETTING: United States of America (USA). METHODS: An experimentally validated three-dimensional nonlinear FEM of the intact ligamentous L3-S1 segment was used and modified to simulate two kinds of SBO at L5. One model had SBO with no change in the length of the spinous process and the other had a small dysplastic spinous process. Von Mises stresses at pars interarticularis were analyzed in the six degrees of lumbar motion with 400 N axial compression, which simulates the standing position. The range of motion at L4/5 and L5/S1 were also calculated. RESULTS: It was observed that the stresses in all the models were similar, and there was no change in the highest stress value when compared to the intact model. The range of motion was also similar in all the models. The lumbar kinematics of SBO was thus shown to be similar to the intact model. CONCLUSION: SBO does not alter lumbar biomechanics with respect to stress and range of motion. The high coincidence of spondylolysis in spines with SBO may not be due to the mechanical factors.

Biomechanical Phenomena↗
PubMed2005

Biomechanical rationale of endoscopic decompression for lumbar spondylolysis as an effective minimally invasive procedure - a study based on the finite element analysis.

We evaluated the biomechanical behavior of the endoscopic decompression for lumbar spondylolysis using the finite element technique. An experimentally validated, 3-dimensional, non-linear finite element model of the intact L3 - 5 segment was modified to create the L4 bilateral spondylolysis and left-sided endoscopic decompression. The model of Gill's laminectomy (conventional decompression surgery of the spondylolysis) was also created. The stress distributions in the disc and endplate regions were analyzed in response to 400 N compression and 10.6 Nm moment in clinically relevant modes. The results were compared among three models. During the flexion motion, the pressure in the L4/5 nucleus pulposus was 0.09, 0.09 and 0.16 (MPa) for spondylolysis, endoscopic decompression and Gill's procedure, respectively. The corresponding stresses in the annulus fibrosus were 0.65, 0.65 and 1.25 (MPa), respectively. The stress at the adjoining endplates showed an about 2-fold increase in the Gill's procedure compared to the other two models. The stress values for the endoscopic and spondylolysis models were of similar magnitudes. In the other motions, i. e., extension, lateral bending, or axial rotation, the results were similar among all of the models. These results indicate that the Gill's procedure may lead to an increase in intradiscal pressure (IDP) and other biomechanical parameters after the surgery during flexion, whereas the endoscopic decompression did not change the segment mechanics after the surgery, as compared to the spondylolysis alone case. In conclusion, endoscopic decompression of the spondylolysis, as a minimally invasive surgery, does not alert mechanical stability by itself.

Biomechanical Phenomena↗
PubMed2005

Role of mechanical factors in the evaluation of pedicle screw type spinal fixation devices.

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.

Animals↗
PubMed2000

Location of the first and second sacral nerve roots in relation to pedicle screw placement.

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.

Bone Screws↗
PubMed1998

Anterior tibial artery and its actual projection on the lateral aspect of the tibia: a cadaveric study.

The anterior tibial artery (ATA) is at risk of injury during high tibial osteotomy, Ilizarov wire placement, pin placement in external fixation, or proximal locking screw insertion, as the artery is not visualized intraoperatively. The ATA is anchored to the oval foramen of the interosseous membrane on the proximal tibia by the deep fascia and recurrent genicular vascular branches. Segment 1 (from the bifurcation of the popliteal artery to the level of the interosseous foramen) and the proximal part of segment 2 (from the interosseous foramen to the level where the artery crosses the anterior border of the tibia) may be damaged when pin, wire or screw placement is directed posterolaterally at that level. Distally, a straight mediolateral pin or Ilizarov wires may lacerate the artery. Segment 2 of the ATA descends against the interosseous membrane in its proximal part, which is projected on the posterior third of the tibia relative to the sagittal plane; in its middle part, it runs close to the lateral cortex of the tibia, it is projected on the middle third of the tibia; in its distal part it runs gradually towards the anterior third of the tibia and contacts with the anterior third of the tibial cortical surface. This information may help reduce risk of injury to the ATA during high tibial osteotomy, external fixation and pin placement or insertion of locking screws.

Bone Nails↗
PubMed1998

Nonunion of pelvic fractures.

Nonunion of the pelvic bones is uncommon. It may be under-diagnosed because of the difficulty in visualization of the fracture and interpretation with conventional radiography. The authors report four cases of nonunion involving the pelvic bones. Nonunion of the posterior ilium was occult in two patients and was not apparent on routine radiographs. The two patients with nonunion of the anterior iliac crest had major displacement caused by muscle pull. Pain on weight-bearing and awkward gait were common symptoms. All patients required surgical management for symptomatic relief.

Accidents, Traffic↗
PubMed1997

Anatomic considerations of the lumbar isthmus.

STUDY DESIGN: A morphometric study of lumbar isthmus from L1 to L5 on 30 dried lumbar spines was conducted. OBJECTIVE: To provide anatomic data about the lumbar isthmus and to quantitatively evaluate structural features of the lumbar isthmus and its relationship to adjacent anatomic structures. SUMMARY OF BACKGROUND DATA: There are very few anatomic studies about the lumbar isthmus, and no study describes the relationship of the lumbar isthmus to its adjacent structures. METHODS: Direct measurements using digital calipers and a goniometer were taken from 30 dried lumbar spines. Anatomic evaluation focused on the lumbar isthmus and its related structures, the isthmus pedicle, and superior and inferior facets. Seven linear and four angular parameters of the lumbar isthmus were determined. RESULTS: The length of the superior edge of the isthmus gradually increased from L2 to L5 (from 8.22 +/- 1.43 mm at L2 to 10.44 +/- 1.90 mm at L5), and that of its inferior edge progressively decreased from L2 to L5 (from 8.67 +/- 1.76 mm at L2 to 6.34 +/- 1.74 mm at L5). The superoinferior diameter of the isthmus decreased from L3 to L5 (from 13.87 +/- 1.77 mm at L3 to 13.26 +/- 2.49 mm at L5). The superior edge of the isthmus was the thinnest at L4 (1.62 +/- 0.58 mm), and its thickness inferiorly increased from L1 to L5 (from 6.71 +/- 1.47 mm at L1 to 7.76 +/- 1.08 mm at L5). The medial and caudal inclination of the isthmus with respect to the pedicle gradually increased from L1 to L5 (from 112.3 degrees +/- 13.8 degrees at L1 to 119.2 degrees +/- 11.2 degrees at L5 medial inclination and from 132.5 degrees +/- 8.8 degrees at L2 to 139.0 degrees +/- 12.1 degrees at L5 caudal inclination, respectively). The dimensions of the lumbar isthmus were positively correlated to dimensions of the pedicle and orientations of the facets. CONCLUSIONS: This study provides detailed anatomic data of the lumbar isthmus. Anatomic parameters of the lumbar isthmus are related to the vertebral levels and have a significant correlation with the angles of the facets and the dimensions of the pedicles. The vulnerability of the pars interarticularis of the fifth lumbar vertebra has been anatomically confirmed.

Analysis of Variance↗
PubMed1997

Morphologic considerations of the first sacral pedicle for iliosacral screw placement.

STUDY DESIGN: Morphometric, radiographic, and computed tomographic evaluation of the pedicle of the first sacral vertebra was performed, and the pedicle's spatial relation with the posterior surface of the ilium was defined. OBJECTIVES: To facilitate accurate localization of the entry site of the iliosacral pedicular screw on the posterior surface of the ilium, to provide optimal length and direction of iliosacral screw placement, and to investigate the feasibility of inserting two screws through the first sacral vertebral pedicle for unstable posterior pelvic fixation. METHODS: Anterior and posterior pedicular height, pedicular depth, alar depth, and posterior alar height of S1 vertebrae were measured in 11 body pelves bilaterally. Sacral pedicular height was also measured on the outlet view radiograph as visualized during intraoperative fluoroscopy, and compared with actual anatomic pedicular height. The distance from the posterior limit of the ilium to the S1 ala, pedicle, and pedicle axis, and the distance between the outer table of the ilium and anterior cortex of the sacrum were measured on axial computed tomography scans. Finally, parasagittal sections of the sacral were made to assess the safety zone for placement of two pedicular screws into the vertebral body. RESULTS: The mean anterior and posterior pedicular heights were 30.2 and 26.1 mm, respectively. The depths of the pedicle and ala were 27.8 and 45.8 mm, respectively. The mean posterior alar height was 28.7 mm. The mean first sacral pedicular height measured on the outlet-view radiographs was 20 mm, which was significantly less (P < 0.0001) than the actual gross anatomic pedicular height. The mean distance from the posterior limit of the ilium to the pedicle axis projection point on axial computed tomography scans was 32.5 mm, and the mean distance from this point to the greater sciatic notch was 38.6 mm. The mean distance between the outer table of the ilium and the anterior cortex of the sacrum was 105.2 mm. The safety margin for two closely inserted pedicular screws was only 4 to 6 mm. CONCLUSIONS: This study suggests that placement of one screw through the S1 pedicle into the vertebral body is safer, and routine placement of two sacral pedicular screws may be difficult. The optimal starting point for placement of single iliosacral screw is 3 to 3.5 cm anterior to the posterior border of the iliac bone in the sagittal plans, and 3.5 to 4 cm cephalad to the greater sciatic notch. The screw should be directed perpendicular to the outer surface of the table from this entry point. The safe length of the iliosacral pedicular screw is up to 80 mm.

Adult↗
PubMed1997

Anterior iliac crest bone graft. Anatomic considerations.

STUDY DESIGN: A morphologic study of the anterior part of the iliac crest was performed. OBJECTIVE: To define the anatomic characteristics of the anterior part of the ilium and to determine an optimal area to harvest the iliac bone graft from the anterior iliac crest. SUMMARY OF BACKGROUND DATA: Stress fracture or avulsion fracture of the anterior cut for anterior iliac crest graft have been noted previously. However, there is insufficient published information on the morphology of the anterior part of the ilium relative to the optimal location of harvesting the bone graft. METHODS: Direct measurements using digital calipers were taken from 30 dried human pelves and 10 cadaveric pelves. The thickness of the anterior part of the ilium was measured, with different starting points on the iliac crest. The length of the bicortical iliac bone graft also was determined. RESULTS: The thickest portion of the ilium was 18.9 +/- 2.3 mm at the iliac tubercle, which was 45% thicker than at a point 3 cm posterior to the anterior superior iliac spine. The thick region of the anterior iliac crest extended 54.0 +/- 10.2 mm posteriorly from a point 3 cm posterior to the anterior superior iliac spine. The mean length of a 10 mm thick bicortical iliac tubercle bone graft was 36.8 +/- 8.7 mm. CONCLUSIONS: The region around the iliac tubercle is suitable for harvesting bicortical or tricortical bone graft.

Bone Transplantation↗
PubMed1997

Anatomic considerations of the principal nutrient foramen and artery on internal surface of the ilium.

Direct measurements of the nutrient foramen of thirty dried ilia using digital calipers and observations of the nutrient a. from ten cadaveric specimens were made in the present study. The nutrient foramen was situated 12.5 +/- 2.7 mm lateral to the anterosuperior sacroiliac joint line but perpendicular to this line and 23.5 +/- 5.8 mm above the pelvic brim parallel to the sacroiliac joint line. The nutrient a. originated from the iliolumbar a. as it coursed across the anterosuperior aspect of the sacroiliac joint. The present anatomic study indicates that the nutrient a. on the internal surface of the ilium is prone to injury as a result of traumatic disruption of the sacroiliac joint, sacral alar fractures and during the anterior approach to the sacroiliac joint.

Aged↗
PubMed1997

Screw placement in the lumbar vertebral isthmus.

Anatomic parameters of the isthmus from L1 to L5 were measured in 30 dried lumbar spines. All measured parameters were fairly constant from L1 to L5. The mean values of the core length, thickness of the superior and inferior borders of the isthmus, superoinferior diameter and posterior and medial inclinations of the lumbar isthmus at L5 were 39.9 +/- 2.3 mm, 2.0 +/- 0.9 mm, 8.9 +/- 1.0 mm, 13.2 +/- 2.5 mm, 35.9 degrees +/- 5.7 degrees and 31.8 degrees +/- 6.3 degrees, respectively. This study shows that a 40 mm long, 4 to 5 mm diameter screw should be inserted in the lumbar vertebral isthmus at an angle of 30 degrees laterally and anteriorly.

Bone Screws↗
PubMed1997

Anatomic basis of lag screw placement in the anterior column of the acetabulum.

The projection point of the axis of the anterior column of the acetabulum on the outer table of the iliac wing was determined in 15 adult bony hemipelves. The optimal entry point for lag screw fixation in the anterior column was located 16 +/- 3.9 mm superior to the midpoint of the line connecting the apex of the sciatic notch with the notch between anterior superior iliac spine and anterior inferior iliac spine, and 46 +/- 5.9 mm superior to the acetabular rim. The mean inclination of the projected axis was 90.6 degrees +/- 5.0 degrees in the sagittal plane and 29.0 degrees +/- 4.4 degrees in the transverse plane. These data may facilitate insertion of a lag screw into the anterior acetabular column and minimize the risk of articular violation or cortical penetration because there is a narrow margin of safety. The lag screw placement also may be aided by palpating the anterior column with a finger and by intraoperative fluoroscopy for visualization of the hip joint and the anterior column in the obturator or pelvic outlet views.

Acetabulum↗
PubMed1997

Cartilage and synovium of the human atlanto-odontoid joint. An anatomic and histological study.

The surface area, thickness and composition of articular cartilage of the atlanto-odontoid joints were investigated in twenty human cadaveric cervical spine specimens. The specimens were also examined grossly and by light microscopy to determine the location of the synovium. The anterior arch of the atlas and ventral and dorsal articular surfaces of the dens were covered with hyaline cartilage. The mean values of the articular surface areas on the ventral surface of the dens and anterior arch of the atlas were 55.10 and 58.24 mm2, respectively. The mean thickness of the articular cartilage of the anterior arch of the atlas, ventral and dorsal surfaces of the dens was 0.80, 0.81 and 0.82 mm, respectively. Synovial membranes were associated with the joint capsules and surrounding tissues of both anterior and posterior atlanto-odontoid joint spaces, where the synovial membranes were attached to the margins of the articular surfaces of the dens and anterior arch of the atlas anteriorly and the region of the cruciate ligament immediately peripheral to the cartilage region apposed to the dens and dens cartilage itself, posteriorly.

Adult↗
PubMed1997

Anatomic considerations for uncovertebral involvement in cervical spondylosis.

Morphometric analysis of 54 dry cervical spines from C3 to C7 (a total of 270 cervical vertebrae) and bilateral dissection of 10 anatomic specimen cervical spines were performed. The uncinate processes were significantly higher at C4 to C6 (5.8 +/- 1.1 mm to 6.1 +/- 1.3 mm) levels than at C3 or C7 levels. The anteroposterior diameter of the intervertebral foramina was smaller at the C4, C5, and C6 levels compared with that at the C3 or C7 levels. The length of nerve root between the lateral border of dural tube and medial border of vertebral artery gradually increased from C3 (3.3 +/- 1.1 mm) to C7 (8.1 +/- 2.1 mm). A combination of higher uncinate process, smaller anteroposterior diameter of intervertebral foramina, and longer course of nerve roots in close proximity of the uncovertebral joints at the C4 to C6 levels may explain the predilection of nerve root compression by uncovertebral osteophytes at these levels. The distance from apex of the uncinate process to medial border of the transverse foramen gradually increased from C3 (1.7 +/- 0.8 mm) to C7 (3.3 +/- 1.0 mm), which may predispose the midcervical level to compression of the vertebral artery by laterally projecting uncovertebral osteophytes.

Adult↗
PubMed1997

The relationship of lumbosacral plexus to the sacrum and the sacroiliac joint.

The lumbosacral plexus was dissected bilaterally in 20 adult cadavers to define the anatomic relationship of the lumbosacral plexus to the sacrum and the sacroiliac joint. All results are mean values +/- standard deviation. The length of the nerve roots of the lumbosacral plexus gradually decreased from L-4 to S-3 (from 93.8 +/- 6.9 mm in males and 108.7 +/- 7.7 mm in females at L-4 to 43.7 +/- 4.3 mm in males and 49.0 +/- 7.6 mm in females at S-3). The angle projected by the nerve roots of the lumbosacral plexus with respect to the sagittal plane gradually increased from L-4 to S-3 (from 14.3 degrees +/- 3.4 degrees in males and 16.7 degrees +/- 4.8 degrees in females at L-4 to 51.8 degrees +/- 9.0 degrees in males and 57.8 degrees +/- 9.1 degrees in females at S-3). The width of the nerve roots of the lumbosacral plexus was greatest at S-1 (9.8 +/- 1.8 mm in males, 8.6 +/- 1.5 mm in females). The L-5 nerve root was the thickest in males (4.4 +/- 0.5 mm), and the S-1 nerve root was thickest in females (4.3 +/- 0.4 mm). The lumbosacral trunk was 30.0 +/- 9.0 mm in length in males and 32.0 +/- 6.0 mm in females; 11.4 +/- 1.8 mm wide in males and 11.2 +/- 1.5 mm in females; and 4.4 +/- 0.5 mm thick in males and 4.0 +/- 0.6 mm in females. The fifth lumbar nerve root and lumbosacral trunk coursed across the sacroiliac at a level 2.0 +/- 0.2 cm below the pelvic brim and were relatively fixed to the sacral ala with fibrous connective tissue.

Aged↗
PubMed1997

Management of infected defect nonunion of the metacarpals.

A 30-year-old man sustained a displaced closed fracture of the fourth metacarpal bone, which was treated by open reduction and internal fixation with Kirschner wires. Severe postoperative infection led to a segmental defect with shortening of the fourth metacarpal bone and infected defect nonunion of the fifth metacarpal bone. After serial debridements and intravenous antibiotics, the infection was controlled. An AO external minifixator was applied to restore the length of the fourth metacarpal bone and to stabilize the fourth and fifth metacarpals, and iliac bone grafting was performed, leading to complete healing and restoration of normal hand function.

Adult↗
PubMed1996

Anatomic considerations for posterior approach to the sacroiliac joint.

STUDY DESIGN: This anatomic study describes a new intraosseous, posterior approach to the sacroiliac joint. OBJECTIVES: To define a transosseous approach to the sacroiliac joint in which a triangular bony window is raised on the posterosuperior aspect of the ilium that provides improved access to the sacroiliac joint for posterior fusion. SUMMARY OF BACKGROUND DATA: A posterior approach to the sacroiliac joint has been widely used for debridement of infectious diseases and for fusion. Most conventional approaches to the sacroiliac joint are interosseous, and there is a relative lack of information on transiliac approaches. METHODS: The projection of the sacroiliac joint on the outer table of the ilium and the thickness of the posterior ilium forming part of the sacroiliac joint were determined in 15 cadaveric pelves. A right angle, triangular bony window was raised from the posterior ilium to investigate the suitability of a transiliac approach in performing sacroiliac debridement and arthrodesis. A horizontal reference line 3-3.5 cm in length was drawn between a point 1 cm anterosuperior to the posteroinferior iliac spine and a point 1.5 cm superior to the superior border of the greater sciatic notch. A vertical reference line was extended superiorly for 2-2.5 cm perpendicular to and beginning at the anterior end of the horizontal reference line. The oblique arm of the right triangle was created by joining the superior end of the vertical reference line to the posterior end of the horizontal line. RESULTS: Thirty percent to fifty percent of the articular surface of the iliac bone was removed with this triangular segment of bone, and a corresponding area of the sacral articular surface was visualized directly. It was possible to remove the rest of the articular cartilage with angled curettes in all specimens. CONCLUSIONS: This approach facilities improved access to the sacroiliac joint for debridement and arthrodesis with minimal soft tissue dissection and iliac bone resection.

Adult↗