The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Yuri W Novitsky - One of the best experts on this subject based on the ideXlab platform.
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assessment of myofascial medialization following posterior component separation via transversus abdominis muscle release in a Cadaveric Model
Hernia, 2018Co-Authors: Arnab Majumder, Heidi J Miller, L M Del Campo, Hooman Soltanian, Yuri W NovitskyAbstract:Purpose Posterior component separation (PCS) via the transversus abdominis release (TAR) procedure continues to gain popularity. However, neither the physiologic basis nor the extent of myofascial medialization after TAR is established. We aimed to assess both anterior and posterior rectus fascia (AF and PF) medialization following each step of the TAR procedure.
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assessment of myofascial medialization following posterior component separation via transversus abdominis muscle release in a Cadaveric Model
Hernia, 2018Co-Authors: Arnab Majumder, Heidi J Miller, L M Del Campo, Hooman Soltanian, Yuri W NovitskyAbstract:Posterior component separation (PCS) via the transversus abdominis release (TAR) procedure continues to gain popularity. However, neither the physiologic basis nor the extent of myofascial medialization after TAR is established. We aimed to assess both anterior and posterior rectus fascia (AF and PF) medialization following each step of the TAR procedure. Ten fresh cadavers underwent PCS via TAR. Steps included midline laparotomy (MLL), retrorectus dissection (RRD), incision of the posterior rectus sheath (IPL), transversus abdominis muscle division (TAD), and retromuscular dissection (RMD). Medial advancement of AF and PF was measured following application of 2.5, 5.0 lb, and maximal tension to the fascial edge. Values are represented as mean advancement past midline in centimeters. MLL allowed advancement of 2.5, 3.7, and 4.9 cm. RRD provided advancement of 4.1, 5.9, and 7.6 cm for AF and 4.4, 6.2, and 7.5 cm for PF. IPL provided advancement of 4.2, 6.1, and 8.0 cm for AF and 4.6, 6.6, and 8.3 cm for PF. TAD provided advancement of 4.5, 6.6, and 8.6 cm for AF and 5.3, 7.5, and 9.5 cm for PF. RMD provided advancement of 5.5, 7.9, and 9.9 cm for AF and 6.9, 9.6, and 11.2 cm for PF. Overall, the complete TAR procedure provided AF advancement of 102% and PF advancement of 129%, over baseline. The TAR procedure provides for substantial medial advancement of both anterior and posterior myofascial components of the abdominal wall. Retromuscular dissection deep to the divided transversus abdominis muscle appears to be the key step of the procedure, allowing for effective reconstruction of very wide (≈ 20 cm) defects.
Paul C. Mcafee - One of the best experts on this subject based on the ideXlab platform.
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biomechanical and anatomical considerations in lumbar spinous process fixation an in vitro human Cadaveric Model
The Spine Journal, 2014Co-Authors: Ashley A Murgatroyd, Kathleen P. Mullinix, Bryan W Cunningham, Paul C. McafeeAbstract:Abstract Background context Although multiple mechanisms of device attachment to the spinous processes exist, there is a paucity of data regarding lumbar spinous process morphology and peak failure loads. Purpose Using an in vitro human Cadaveric spine Model, the primary objective of the present study was to compare the peak load and mechanisms of lumbar spinous process failure with variation in spinous process hole location and pullout direction. A secondary objective was to provide an in-depth characterization of spinous process morphology. Study design Biomechanical and anatomical considerations in lumbar spinous process fixation using an in vitro human Cadaveric Model. Methods A total of 12 intact lumbar spines were used in the current investigation. The vertebral segments (L1–L5) were randomly assigned to one of five treatment groups with variation in spinous process hole placement and pullout direction: (1) central hole placement with superior pullout (n=10), (2) central hole placement with inferior pullout (n=10), (3) inferior hole placement with inferior pullout (n=10), (4) superior hole placement with superior pullout (n=10), and (5) intact spinous process with superior pullout (n=14). A 4-mm diameter pin was placed through the hole followed by pullout testing using a material testing system. As well, the bone mineral density (BMD) (g/cm 3 ) was measured for each segment. Data were quantified in terms of anatomical dimensions (mm), peak failure loads (newtons [N]), and fracture mechanisms, with linear regression analysis to identify relationships between anatomical and biomechanical data. Results Based on anatomical comparisons, there were significant differences between the anteroposterior and cephalocaudal dimensions of the L5 spinous process versus L1–L4 (p .05). However, a significant linear correlation was observed between peak failure load and anteroposterior and cephalocaudal dimensions (p Conclusions The present study demonstrated that variation in spinous process hole placement did not significantly influence failure load. However, there was a strong linear correlation between peak failure load and the anteroposterior and cephalocaudal anatomical dimensions. From a clinical standpoint, the findings of the present study indicate that attachment through the spinous process provides a viable alternative to attachment around the spinous processes. In addition, the anatomical dimensions of the lumbar spinous processes have a greater influence on biomechanical fixation than either hole location or BMD.
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biomechanical evaluation of total disc replacement arthroplasty an in vitro human Cadaveric Model
Spine, 2003Co-Authors: Bryan W Cunningham, Jeffrey D Gordon, Anton E Dmitriev, Paul C. McafeeAbstract:STUDY DESIGN This in vitro biomechanical study was undertaken to quantify the multidirectional intervertebral kinematics following total disc replacement arthroplasty compared to conventional stabilization techniques. OBJECTIVE Using an in vitro human Cadaveric Model, the primary objective was to compare the multidirectional flexibility properties and map the center of intervertebral rotation of total disc arthroplasty versus conventional threaded fusion cages and cages augmented with transpedicular fixation for single-level spinal instrumentation. SUMMARY OF BACKGROUND DATA The utilization of motion-preserving implants versus instrumentation systems, which stabilize the operative segments, necessitates improved understanding of their comparative biomechanical properties. METHODS A total of eight human Cadaveric lumbosacral spines (L2 to sacrum) were utilized in this investigation and biomechanically evaluated under the following L4-L5 reconstruction conditions: 1) intact spine; 2) SB Charite disc prosthesis; 3) BAK cages; and 4) BAK cages + ISOLA pedicle screw/rod fixation (anteroposterior). The superior (L3-L4) and inferior (L5-S1) intervertebral levels remained uninstrumented to quantify adjacent level properties. Multidirectional flexibility included pure, unconstrained moments (+/-8 Nm) in axial rotation, flexion-extension, and lateral bending, with quantification of the operative and adjacent level range of motion and neutral zone, which were normalized to the intact spine condition. RESULTS The SB Charite prosthesis indicated an average percentage increase in axial rotation range of motion by 44% compared to the intact condition (P 0.05), whereas the BAK and anteroposterior stabilization groups resulted in significant decreases in range of motion (BAK = 57%, anteroposterior = 93%) (P < 0.05) when compared to the intact and SB Charite conditions. Based on flexion-extension radiographs, the intervertebral centers of rotation were in the posterior one-third of the operative intervertebral disc only for the SB Charite reconstruction and intact spine condition, with definitive evidence of physiologic intervertebral translation (intact 2.06 +/- 77 mm; SB III = 1.9 +/- 0.98 mm). CONCLUSIONS Total disc arthroplasty serves as the next frontier in the surgical management of discogenic spinal pathology. The SB Charite restored motion to the level of the intact segment in flexion-extension and lateral bending and increased motion in axial rotation. The anterior annular resection necessary for device implantation and unconstrained design of the prosthesis account for this change in rotation. The normal lumbar flexion-extension axis of rotation is an ellipse rather than a single point. Only disc replacement rather than pedicle instrumentation or BAK interbody instrumentation preserves the kinematic properties and normal mapping of segmental motion at the operative and adjacent intervertebral disc levels.
Bryan W Cunningham - One of the best experts on this subject based on the ideXlab platform.
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comprehensive biomechanical analysis of three reconstruction techniques following total sacrectomy an in vitro human Cadaveric Model
Journal of Neurosurgery, 2017Co-Authors: Mohamed Macki, Ashley A Murgatroyd, Kathleen P. Mullinix, Bryan W Cunningham, Rafael De La Garzaramos, Xiaolei Sun, Brandon A Mccutcheon, Mohamad Bydon, Ziya L GokaslanAbstract:OBJECTIVEAggressive sacral tumors often require en bloc resection and lumbopelvic reconstruction. Instrumentation failure and pseudarthrosis remain a clinical concern to be addressed. The objective in this study was to compare the biomechanical stability of 3 distinct techniques for sacral reconstruction in vitro.METHODSIn a human Cadaveric Model study, 8 intact human lumbopelvic specimens (L2–pelvis) were tested for flexion-extension range of motion (ROM), lateral bending, and axial rotation with a custom-designed 6-df spine simulator as well as axial compression stiffness with the MTS 858 Bionix Test System. Biomechanical testing followed this sequence: 1) intact spine; 2) sacrectomy (no testing); 3) Model 1 (L3–5 transpedicular instrumentation plus spinal rods anchored to iliac screws); 4) Model 2 (addition of transiliac rod); and 5) Model 3 (removal of transiliac rod; addition of 2 spinal rods and 2 S-2 screws). Range of motion was measured at L4–5, L5–S1/cross-link, L5–right ilium, and L5–left ilium....
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biomechanical and anatomical considerations in lumbar spinous process fixation an in vitro human Cadaveric Model
The Spine Journal, 2014Co-Authors: Ashley A Murgatroyd, Kathleen P. Mullinix, Bryan W Cunningham, Paul C. McafeeAbstract:Abstract Background context Although multiple mechanisms of device attachment to the spinous processes exist, there is a paucity of data regarding lumbar spinous process morphology and peak failure loads. Purpose Using an in vitro human Cadaveric spine Model, the primary objective of the present study was to compare the peak load and mechanisms of lumbar spinous process failure with variation in spinous process hole location and pullout direction. A secondary objective was to provide an in-depth characterization of spinous process morphology. Study design Biomechanical and anatomical considerations in lumbar spinous process fixation using an in vitro human Cadaveric Model. Methods A total of 12 intact lumbar spines were used in the current investigation. The vertebral segments (L1–L5) were randomly assigned to one of five treatment groups with variation in spinous process hole placement and pullout direction: (1) central hole placement with superior pullout (n=10), (2) central hole placement with inferior pullout (n=10), (3) inferior hole placement with inferior pullout (n=10), (4) superior hole placement with superior pullout (n=10), and (5) intact spinous process with superior pullout (n=14). A 4-mm diameter pin was placed through the hole followed by pullout testing using a material testing system. As well, the bone mineral density (BMD) (g/cm 3 ) was measured for each segment. Data were quantified in terms of anatomical dimensions (mm), peak failure loads (newtons [N]), and fracture mechanisms, with linear regression analysis to identify relationships between anatomical and biomechanical data. Results Based on anatomical comparisons, there were significant differences between the anteroposterior and cephalocaudal dimensions of the L5 spinous process versus L1–L4 (p .05). However, a significant linear correlation was observed between peak failure load and anteroposterior and cephalocaudal dimensions (p Conclusions The present study demonstrated that variation in spinous process hole placement did not significantly influence failure load. However, there was a strong linear correlation between peak failure load and the anteroposterior and cephalocaudal anatomical dimensions. From a clinical standpoint, the findings of the present study indicate that attachment through the spinous process provides a viable alternative to attachment around the spinous processes. In addition, the anatomical dimensions of the lumbar spinous processes have a greater influence on biomechanical fixation than either hole location or BMD.
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biomechanical evaluation of total disc replacement arthroplasty an in vitro human Cadaveric Model
Spine, 2003Co-Authors: Bryan W Cunningham, Jeffrey D Gordon, Anton E Dmitriev, Paul C. McafeeAbstract:STUDY DESIGN This in vitro biomechanical study was undertaken to quantify the multidirectional intervertebral kinematics following total disc replacement arthroplasty compared to conventional stabilization techniques. OBJECTIVE Using an in vitro human Cadaveric Model, the primary objective was to compare the multidirectional flexibility properties and map the center of intervertebral rotation of total disc arthroplasty versus conventional threaded fusion cages and cages augmented with transpedicular fixation for single-level spinal instrumentation. SUMMARY OF BACKGROUND DATA The utilization of motion-preserving implants versus instrumentation systems, which stabilize the operative segments, necessitates improved understanding of their comparative biomechanical properties. METHODS A total of eight human Cadaveric lumbosacral spines (L2 to sacrum) were utilized in this investigation and biomechanically evaluated under the following L4-L5 reconstruction conditions: 1) intact spine; 2) SB Charite disc prosthesis; 3) BAK cages; and 4) BAK cages + ISOLA pedicle screw/rod fixation (anteroposterior). The superior (L3-L4) and inferior (L5-S1) intervertebral levels remained uninstrumented to quantify adjacent level properties. Multidirectional flexibility included pure, unconstrained moments (+/-8 Nm) in axial rotation, flexion-extension, and lateral bending, with quantification of the operative and adjacent level range of motion and neutral zone, which were normalized to the intact spine condition. RESULTS The SB Charite prosthesis indicated an average percentage increase in axial rotation range of motion by 44% compared to the intact condition (P 0.05), whereas the BAK and anteroposterior stabilization groups resulted in significant decreases in range of motion (BAK = 57%, anteroposterior = 93%) (P < 0.05) when compared to the intact and SB Charite conditions. Based on flexion-extension radiographs, the intervertebral centers of rotation were in the posterior one-third of the operative intervertebral disc only for the SB Charite reconstruction and intact spine condition, with definitive evidence of physiologic intervertebral translation (intact 2.06 +/- 77 mm; SB III = 1.9 +/- 0.98 mm). CONCLUSIONS Total disc arthroplasty serves as the next frontier in the surgical management of discogenic spinal pathology. The SB Charite restored motion to the level of the intact segment in flexion-extension and lateral bending and increased motion in axial rotation. The anterior annular resection necessary for device implantation and unconstrained design of the prosthesis account for this change in rotation. The normal lumbar flexion-extension axis of rotation is an ellipse rather than a single point. Only disc replacement rather than pedicle instrumentation or BAK interbody instrumentation preserves the kinematic properties and normal mapping of segmental motion at the operative and adjacent intervertebral disc levels.
Arnab Majumder - One of the best experts on this subject based on the ideXlab platform.
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assessment of myofascial medialization following posterior component separation via transversus abdominis muscle release in a Cadaveric Model
Hernia, 2018Co-Authors: Arnab Majumder, Heidi J Miller, L M Del Campo, Hooman Soltanian, Yuri W NovitskyAbstract:Purpose Posterior component separation (PCS) via the transversus abdominis release (TAR) procedure continues to gain popularity. However, neither the physiologic basis nor the extent of myofascial medialization after TAR is established. We aimed to assess both anterior and posterior rectus fascia (AF and PF) medialization following each step of the TAR procedure.
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assessment of myofascial medialization following posterior component separation via transversus abdominis muscle release in a Cadaveric Model
Hernia, 2018Co-Authors: Arnab Majumder, Heidi J Miller, L M Del Campo, Hooman Soltanian, Yuri W NovitskyAbstract:Posterior component separation (PCS) via the transversus abdominis release (TAR) procedure continues to gain popularity. However, neither the physiologic basis nor the extent of myofascial medialization after TAR is established. We aimed to assess both anterior and posterior rectus fascia (AF and PF) medialization following each step of the TAR procedure. Ten fresh cadavers underwent PCS via TAR. Steps included midline laparotomy (MLL), retrorectus dissection (RRD), incision of the posterior rectus sheath (IPL), transversus abdominis muscle division (TAD), and retromuscular dissection (RMD). Medial advancement of AF and PF was measured following application of 2.5, 5.0 lb, and maximal tension to the fascial edge. Values are represented as mean advancement past midline in centimeters. MLL allowed advancement of 2.5, 3.7, and 4.9 cm. RRD provided advancement of 4.1, 5.9, and 7.6 cm for AF and 4.4, 6.2, and 7.5 cm for PF. IPL provided advancement of 4.2, 6.1, and 8.0 cm for AF and 4.6, 6.6, and 8.3 cm for PF. TAD provided advancement of 4.5, 6.6, and 8.6 cm for AF and 5.3, 7.5, and 9.5 cm for PF. RMD provided advancement of 5.5, 7.9, and 9.9 cm for AF and 6.9, 9.6, and 11.2 cm for PF. Overall, the complete TAR procedure provided AF advancement of 102% and PF advancement of 129%, over baseline. The TAR procedure provides for substantial medial advancement of both anterior and posterior myofascial components of the abdominal wall. Retromuscular dissection deep to the divided transversus abdominis muscle appears to be the key step of the procedure, allowing for effective reconstruction of very wide (≈ 20 cm) defects.
Thay Q Lee - One of the best experts on this subject based on the ideXlab platform.
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effect of posterior shoulder tightness on internal impingement in a Cadaveric Model of throwing
Knee Surgery Sports Traumatology Arthroscopy, 2015Co-Authors: Teruhisa Mihata, Jeffrey Gates, Michelle H Mcgarry, Masashi Neo, Thay Q LeeAbstract:Posterior shoulder tightness is common in throwing athletes, especially those with symptomatic shoulder internal impingement. The role of posteroinferior capsular contracture in the pathoetiologies of throwing-related injuries caused by shoulder internal impingement remains unclear. The purpose of this study was to assess effect of posterior shoulder tightness on internal impingement in a Cadaveric Model of throwing. Seven fresh-frozen Cadaveric shoulders were tested with the shoulder abducted to 90° and at maximum external rotation to simulate the late cocking phase of throwing motion. Glenohumeral joint contact pressure and area through internal impingement, humeral head shift, and the maximum humeral rotation angle were measured. Posteroinferior capsular plication was performed to simulate posteroinferior capsular tightness and induce glenohumeral internal rotation deficit. Following generation of simulated posteroinferior capsular tightness with resultant glenohumeral internal rotation deficit, glenohumeral contact pressure was significantly increased (P < 0.05), the impinged area of rotator cuff tendon was significantly decreased (P < 0.05), and the humeral head shifted posteriorly (P < 0.05) during shoulder internal impingement. Excessive posteroinferior capsular tightness can cause forceful internal impingement of the shoulder at maximum external rotation position.
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effect of scapular orientation on shoulder internal impingement in a Cadaveric Model of the cocking phase of throwing
Journal of Bone and Joint Surgery American Volume, 2012Co-Authors: Teruhisa Mihata, Michelle H Mcgarry, Bong Jae Jun, Christopher N H Bui, James Hwang, Mitsuo Kinoshita, Thay Q LeeAbstract:Background: Although deviations in scapular orientation are thought to predispose to shoulder injuries in throwing athletes, the biomechanical mechanism underlying shoulder injuries in throwing athletes with an altered scapular orientation remains unclear. Methods: Seven fresh-frozen Cadaveric shoulders were evaluated at 90° of abduction, with the humerus externally rotated from 90° to the maximum angle, to simulate the late cocking phase of the throwing motion. Loads were applied to the deltoid, pectoralis major, latissimus dorsi, teres major, and all rotator cuff muscles. Contact pressure in the glenohumeral joint was measured with use of a pressure sensor. The area of internal impingement was calculated on the basis of three-dimensional position data. Glenohumeral contact pressure and the area of impingement were compared between 20°, 30°, and 40° of internal scapular rotation; between 20°, 30°, and 40° of upward scapular rotation; and between 0° and 10° of anterior scapular tilt. Data were analyzed with use of repeated-measures analysis of variance with the Tukey post hoc test. Results: Contact pressure was at its maximum in the posterior aspect of the glenohumeral joint. The glenohumeral contact pressure and internal impingement area increased with increasing internal scapular rotation. The glenohumeral contact pressure at 40° of internal scapular rotation was significantly (43.4%) greater than that at 20° of internal scapular rotation (p < 0.01), and the impingement area at 40° of internal scapular rotation was significantly (43.1%) greater than that at 20° of internal scapular rotation (p < 0.05). Decreasing upward scapular rotation resulted in an increase in internal impingement area. The internal impingement area at 40° of upward motion was 38.1% less than that at 20° of upward rotation (p < 0.001) and 28.9% less than that at 30° of upward rotation (p < 0.01). Conclusions: Increasing internal scapular rotation and decreasing upward scapular rotation significantly increase glenohumeral contact pressure and the area of impingement of the rotator cuff tendon between the greater tuberosity and glenoid during simulated throwing motion. Clinical Relevance: Shoulder internal impingement is accentuated by increasing internal rotation or decreasing upward rotation of the scapula during the throwing motion.
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a Cadaveric Model of the throwing shoulder a possible etiology of superior labrum anterior to posterior lesions
Journal of Bone and Joint Surgery American Volume, 2005Co-Authors: Mark G Grossman, Michelle H Mcgarry, James E Tibone, David J Schneider, Sergio Veneziani, Thay Q LeeAbstract:Background: It has been speculated that a shift of the throwing arc commonly develops in athletes who perform overhead activities, resulting in greater external rotation and decreased internal rotation caused by anterior capsular laxity and posterior capsular contracture, respectively. Osseous adapt
