Significant Differences In Motion Research Articles

Biomechanical Comparison of Anterior Cervical Plate Fixation Versus Integrated Fixation Cage for Anterior Cervical Discectomy and Fusion.

Cadaveric, biomechanic study. To compare the range of motion profiles of the cervical spine following one-level anterior cervical discectomy and fusion (ACDF) constructs instrumented with either an interbody cage and anterior plate or integrated fixation cage in a cadaveric model. While anterior plates with interbody cages are the most common construct of fixation in ACDF, newer integrated cage-plate devices seek to provide similar stability with a decreased implant profile. However, differences in postoperative cervical range of motion between the 2 constructs remain unclear. Six cadaveric spines were segmented into 2 functional spine units (FSUs): C2-C5 and C6-T2. Each FSU was nondestructively bent in flexion-extension (FE), right-left lateral bending (LB), and right-left axial rotation (AR) at a rate of 0.5°/s under a constant axial load until a limit of 2-Nm was reached to evaluate baseline range of motion (ROM). Matched pairs were then randomly assigned to undergo instrumentation with either the standard anterior cage and plate (CP) or the integrated fixation cage (IF). Following instrumentation, ROM was then remeasured as previously described. For CP fixation, ROM increased by 61.2±31.7% for FE, 36.3±20.4% for LB, and 31.7±19.1% for AR. For IF fixation, ROM increased by 64.2±15.5% for FE, 56.7±39.8% for LB, and 94.5±65.1% for AR. There was no significant difference in motion between each group across FE, LB, and AR. This biomechanical study demonstrated increased motion in both the CP and IF groups relative to the intact, un-instrumented state. However, our model showed no differences in ROM between CP and IF constructs in any direction of motion. These results suggest that either method of instrumentation is a suitable option for ACDF with respect to constructing stiffness at time zero.

Decrease of 7T MR short-term effects with repeated exposure

PurposeAlthough participants in 7 T magnetic resonance (MR) studies tolerate ultra-high field (UHF) well, subjectively experienced short-term effects, such as dizziness, inconsistent movement, nausea, or metallic taste, are reported. Evidence on subjectively experienced short-term effects in multiple exposures to UHF MR is scarce. The purpose of this study is to investigated experience of short-term effects, and occurrence of motion in healthy subjects exposed to seven weekly 7 T MR examinations.MethodsA questionnaire on short-term effects was completed by participants in an fMRI motor skill study. Seven UHF MR examinations were conducted over 7 weeks (exposure number: 1 to 7). Changes of experienced short-term effects were analyzed. Motion in fMRI images was quantified.ResultsThe questionnaire was completed 360 times by 67 participants after one to seven 7T MR examinations. Logistic mixed model analysis showed a significant association between dizziness, inconsistent movement, nausea, and headache and the examination numbers (p<0.03). Exposure to repeated examinations had no significant effect on peripheral nerve stimulation (PNS) or motion of the subjects. The overall experience of a 7T examination improved significantly (p<0.001) with increasing examination numbers.ConclusionDuring multiple 7T examinations, subjects adapt to the strong static field. The short-term effects dizziness, inconsistent movement, nausea, and headache decrease over time as the MR sessions continue and experienced comfort increases. There was no significant difference in motion during the multiple fMRI examinations.

Exploring bixin from Bixa orellana L. seeds: quantification and in silico insights into its anti-cancer potential

Bixin, the key pigment of Bixa orellana L., is an apo-carotenoid found in the seed arils. The present study aimed to quantitatively determine the bixin content of seeds and explore its anti-cancer activity through in silico studies. The bixin content from the seeds of the local genotype, TNMTP8, quantified by RP-HPLC was 4.58 mg per gram. The prediction of pharmacological activity suggested that bixin may serve as a BRAF, MMP9, TNF expression inhibitors, and TP53 expression enhancer. According to molecular docking analysis, bixin interacted with eight different skin cancer targets and had the lowest binding energy compared to the standard drug, 5-fluorouracil. The binding score between bixin and the targets ranged from −4.7 to −8.7 kcal/mol. The targets BRAF and SIRT3 interacted well with bixin, with binding energies as low as −8.3 and −8.7 kcal/mol, respectively. Hence, the dynamic behavior of these two docked complexes throughout a 500 ns trajectory run was investigated further. The Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF) values, and total contacts as a function of time recorded during scrutiny suggest that both complexes were stable. This was validated by post-molecular dynamics analysis using Molecular Mechanics Generalized Born Surface Area (MM-GBSA). Principal component analysis (PCA) was used to analyze the significant differences in motion exhibited by BRAF-Bixin and SIRT3-Bixin. The results showed that bixin is a promising source for potential treatment interventions in skin cancer therapies. Communicated by Ramaswamy H. Sarma

Biomechanical Characterization of Unilateral and Bilateral Posterior Lumbar Interbody Fusion Constructs.

Objectives To compare the biomechanical stability of two-level PLIF constructs with unilateral and bilateral pedicle screw fixations. Methods Six cadaveric lumbar segments were evaluated to assess biomechanical stability in response to pure moment loads applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Each specimen was tested in six sequential configurations: (1) intact baseline; (2) facetectomy; (3) unilateral pedicle screws (UPS); (4) bilateral pedicle screws (BPS); (5) unilateral pedicle screws and cage (UPSC); and (6) bilateral pedicle screws and cage (BPSC). Results Significant reductions in motion were observed when comparing all instrumented conditions to the intact and facetectomy stages of testing. No significant differences in motion between UPS, BPS, UPSC, or BPSC were observed in response to FE range of motion (ROM) or neutral zone (NZ). ROM was significantly higher in the UPS stage compared to BPS in response to LB and AT loading. ROM was significantly higher in UPSC compared to BPSC in response to LB loading only. Similarly, NZ was significantly higher in UPSC compared to BPSC in response to only LB loading. In response to AT loading, ROM was significantly higher during UPS than BPS or BPSC; however, no significant differences were noted between UPSC and BPSC with respect to AT ROM or NZ. Conclusion BPS fixation is biomechanically superior to UPS fixation in multilevel PLIF constructs. This was most pronounced during both LB loading. Interbody support did contribute significantly to immediate stability.

Differences in lower-extremity kinematics between the male military personnel with and without plantar fasciitis

ObjectiveTo evaluate the factors that influence gait by comparing lower extremity kinematics during the stance phase of the gait cycle between individuals with and without plantar fasciitis. DesignA cross-sectional study. SettingMotion analysis research laboratory. ParticipantsThirty subjects with plantar fasciitis and 30 aged-matched controls. Main outcome measure(s)Range of motion of the lower extremity and multi-segment foot during gait using a three-dimensional motion analysis system. ResultsThe plantar fasciitis group showed significant differences in motion in the multi-segment foot, ankle, knee, and hip from the control group during various subphases of the stance phase. Specifically, relative to the control group, the plantar fasciitis group had more rearfoot adduction, forefoot eversion, ankle abduction, and hip abduction. They also had less midfoot dorsiflexion, forefoot dorsiflexion, knee extension, knee external rotation, and hip extension (all Ps < 0.05). ConclusionsIndividuals with plantar fasciitis exhibited more flexibility in the ankle-foot complex and poorer quality of lower-extremity movement than the group that did not have plantar fasciitis. Thus, differences in structures in both the ankle-foot complex as well as those in the hip and knee joints appear to be associated with the presence of plantar fasciitis.

Kinematic analysis of mandibular motion before and after mandibulectomy and mandibular reconstruction in dogs.

To evaluate and quantify the kinematic behavior of canine mandibles before and after bilateral rostral or unilateral segmental mandibulectomy as well as after mandibular reconstruction with a locking reconstruction plate in ex vivo conditions. Head specimens from cadavers of 16 dogs (range in body weight, 30 to 35 kg). Specimens were assigned to undergo unilateral segmental (n = 8) or bilateral rostral (8) mandibulectomy and then mandibular reconstruction by internal fixation with locking plates. Kinematic markers were attached to each specimen in a custom-built load frame. Markers were tracked in 3-D space during standardized loading conditions, and mandibular motions were quantified. Differences in mandibular range of motion among 3 experimental conditions (before mandibulectomy [ie, with mandibles intact], after mandibulectomy, and after reconstruction) were assessed by means of repeated-measures ANOVA. Both unilateral segmental and bilateral rostral mandibulectomy resulted in significantly greater mandibular motion and instability, compared with results for intact mandibles. No significant differences in motion were detected between mandibles reconstructed after unilateral segmental mandibulectomy and intact mandibles. Similarly, the motion of mandibles reconstructed after rostral mandibulectomy was no different from that of intact mandibles, except in the lateral direction. Mandibular kinematics in head specimens from canine cadavers were significantly altered after unilateral segmental and bilateral rostral mandibulectomy. These alterations were corrected after mandibular reconstruction with locking reconstruction plates. Findings reinforced the clinical observations of the beneficial effect of reconstruction on mandibular function and the need for reconstructive surgery after mandibulectomy in dogs.

Early Versus Late Motion Following Volar Plating of Distal Radius Fractures.

Background: Distal radius fractures are common, and the trend in fixation has included the use of locked volar plating. The duration of splinting required after surgery and the effect splinting has upon outcome of the wrist are not clear. Our aim was to compare outcome of patients treated with early versus late motion protocol after volar plating. Methods: Thirty-three patients with distal radius fractures were prospectively and randomly enrolled into an early versus late motion study including volar plating of the distal radius fracture. Early motion included an active and passive wrist motion protocol by 14 days after surgery and delayed motion was initiated at 5 weeks. Fractures were defined as intra-articular and extra-articular, and those with, and without, ulnar styloid fracture. Motion and outcome scores (Disabilities of the Arm, Shoulder and Hand [DASH]/patient-rated wrist evaluation [PRWE]), and strength were measured through 1 year. Results: Wrist motion, DASH, and PRWE scores were only significantly different at 6 weeks with no significant differences at any later time points up to 1 year. One patient had complex regional pain syndrome (CRPS) and one had adhesive capsulitis in the late motion group. Conclusions: Following locked volar plating of distal radius fractures, early motion favored earlier return of motion along with lower DASH, PRWE, and pain scores within first 6 weeks. Although the late motion group had delayed recovery, there were no long-term significant differences in motion, strength, outcome, or pain scores. The 2 cases with complications (CRPS and adhesive capsulitis) did occur in the late motion group and may implicate late motion with these problems.

A new robotic horseback-riding simulator for riding lessons and equine-assisted therapy

Robotic horseback-riding simulators have been successfully used as a substitute for real horses in areas of therapy, riding lessons, fitness, and entertainment, and several have been developed. However, recent research has illuminated significant differences in motion, response, and feel between a real horse and a simulator, which may result in incorrect posture and muscle memory for the rider. In this study, we developed a hybrid kinematic structure horseback-riding simulator to provide more realistic motion than currently available ones. The basic system has 4 degrees of freedom and provides a base motion platform. An additional revolving system with 2 degrees of freedom is mounted on the base platform. Real horse motion data were captured, normalized, filtered, and fitted to provide the motion trajectory. Furthermore, active neck, saddle, and tail mechanisms were implemented to provide realistic simulation. For interactive horse riding, bridle and beat sensors were included to control the simulator motion and a large screen was installed for virtual reality effect. Expert tests were conducted to evaluate the developed horseback-riding system, the results of which indicated that the developed simulator was considered sufficient for riding lessons and therapeutic use.

Adjacent-Level Hypermobility and Instrumented-Level Fatigue Loosening With Titanium and PEEK Rods for a Pedicle Screw System: An In Vitro Study.

Adjacent-level disease is a common iatrogenic complication seen among patients undergoing spinal fusion for low back pain. This is attributed to the postsurgical differences in stiffness between the spinal levels, which result in abnormal forces, stress shielding, and hypermobility at the adjacent levels. In addition, as most patients undergoing these surgeries are osteoporotic, screw loosening at the index level is a complication that commonly accompanies adjacent-level disease. Recent studies indicate that a rod with lower rigidity than that of titanium may help to overcome these detrimental effects at the adjacent level. The present study was conducted in vitro using 12 L1-S1 specimens divided into groups of six, with each group instrumented with either titanium rods or PEEK (polyetheretherketone) rods. The test protocol included subjecting intact specimens to pure moments of 10 Nm in extension and flexion using an FS20 Biomechanical Spine Test System (Applied Test Systems) followed by hybrid moments on the instrumented specimens to achieve the same L1-S1 motion as that of the intact specimens. During the protocol's later phase, the L4-L5 units from each specimen were segmented for cyclic loading followed by postfatigue kinematic analysis to highlight the differences in motion pre- and postfatigue. The objectives included the in vitro comparison of (1) the adjacent-level motion before and after instrumentation with PEEK and titanium rods and (2) the pre- and postfatigue motion at the instrumented level with PEEK and titanium rods. The results showed that the adjacent levels above the instrumentation caused increased flexion and extension with both PEEK and titanium rods. The postfatigue kinematic data showed that the motion at the instrumented level (L4-L5) increased significantly in both flexion and extension compared to prefatigue motion in titanium groups. However, there was no significant difference in motion between the pre- and postfatigue data in the PEEK group.

ACL Reconstruction

Objectives:It has often been suggested that bone-patellar tendon-bone (BTB) grafts heal more quickly to graft tunnels than soft-tissue grafts after ACL reconstruction, due to rapid bone-to-bone healing. Little is known, however, about the motion of the grafts under functional, dynamic loads, or the actual time course for graft-tunnel healing in humans. The goal of this study was to assess the motion of both hamstrings (HS) and BTB grafts during gait at two time points (6 and 52 weeks) after surgery. It was hypothesized that there would be greater graft-tunnel motion in HS than BTB grafts, and that graft motion would be less at 1 year when compared with 6 weeks.Methods:Twelve human subjects underwent anatomic single-bundle ACL reconstruction using either hamstrings (HS) or bone-patellar tendon-bone (BTB) autografts (6 in each group) and extra-cortical fixation. Six 0.8 mm tantalum beads were embedded into the grafts prior to implantation, with pairs of beads located within each bone tunnel and in the mid-substance region. At six weeks and one year after surgery, dynamic stereo X-ray (DSX) images were collected at 100 frames/s while subjects walked on an instrumented treadmill (1.3 m/s). 3D femur and tibia bone models were generated from CT scans. Tibiofemoral kinematics and graft bead positions were analyzed by combining the 3D models with DSX data. Graft-tunnel motion was assessed by determining the maximum range of motion of the most proximal femoral tunnel and most distal tibial tunnel beads along the direction of the bone tunnels during the stance phase of gait. Effects of graft type and time were assessed with a 2-factor ANOVA, with alpha = 0.05.Results:Femoral tunnel motion (mean±s.d.) at 6 weeks was 2.47±0.96 mm (range 0.95-3.44 mm) for BTB and 1.51±0.68 mm (range 0.88-2.41 mm) for HS grafts, decreasing slightly to 2.09±0.84 mm for BTB and 1.37±0.41 for HS grafts by one year. Tibial tunnel motion was 1.45±0.57 mm (range 0.74-2.44 mm) for BTB and 1.43±0.59 mm (range 0.89-2.30 mm) for HS grafts at 6 weeks, and changed little by one year (1.58±0.46 mm for BTB and 1.52±0.57 for HS grafts). Across all time points, femoral graft-tunnel motion was significantly greater for BTB than HS grafts (p=0.004). In the tibial tunnel, there were no significant differences in motion between BTB and HS at 6 weeks or 1 year. For both graft types, there was no significant change in motion between 6 weeks and 1 year.Conclusion:Contrary to the study hypothesis, there was a greater motion relative to the femoral tunnel wall in BTB than HS grafts during walking. Significant graft-tunnel motion also persisted one year after reconstruction. These data suggest that the graft-to-tunnel healing process may occur more slowly then widely believed, especially for BTB grafts. However, all subjects were asymptomatic one year after surgery, and the implications of persistent, small (1-3 mm) movements of the grafts are unknown. These results, however, may have significant implications for graft choice, rehabilitation strategies and timing for return to sports.

Is lateral stabilization enough in thoracolumbar burst fracture reconstruction? A biomechanical investigation

Background contextTraditional reconstruction for burst fractures involves columnar support with posterior fixation at one or two levels cephalad/caudad; however, some surgeons choose to only stabilize the vertebral column. PurposeThe aim was to distinguish biomechanical differences in stability between a burst fracture stabilized through a lateral approach using corpectomy spacers of different end plate sizes with and without integrated screws and with and without posterior fixation. Study design/SettingThis was an in vitro biomechanical study assessing thoracolumbar burst fracture stabilization. MethodsSix human spines (T11–L3) were tested on a six-degrees-of-freedom simulator enabling unconstrained range of motion (ROM) at ±6 N·m in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) after a simulated burst fracture at L1. Expandable corpectomy spacers with/without integrated screws (Fi/F; FORTIFY Integrated/FORTIFY; Globus Medical, Inc., Audubon, PA, USA) were tested with different end plate sizes (21×23 mm, 22×40–50 mm). Posterior instrumentation (PI) via bilateral pedicle screws and rods was used one level above and one level below the burst fracture. Lateral plate (LP) fixation was tested. Devices were tested in the following order: intact; Fi21×23; Fi21×23+PI; F21×23+PI+LP; F21×23+LP; F22×40–50+LP; F22×40–50+PI+LP; Fi22×40–50+PI; Fi22×40–50. ResultsIn FE and AR, constructs without PI showed no significant difference (p<.05) in stability compared with intact. In LB, F22×40–50+LP showed a significant increase in stability relative to intact, but no other construct without PI reached significance. In FE and LB, circumferential constructs were significantly more stable than intact. In AR, no construct showed significant differences in motion when compared with the intact condition. ConclusionsConstructs without posterior fixation were the least stable of all tested constructs. Circumferential fixation provided greater stability in FE and LB than lateral fixation and intact. Axial rotation showed no significant differences in any construct compared with the intact state.

Assessment of Impact of Early Stroke Rehabilitation on Hip Joint Mobility of the Affected Leg in Patients after Cerebrovascular Accidents

One of the main priorities of stroke rehabilitation is regaining patients’ independence in basic everyday activities. This paper is aimed at assessing impact of early stroke rehabilitation on hip joint mobility of the affected leg in patients after cerebrovascular accidents. The study included 30 subjects (13 men and 17 women) aged on average ±66.1, with hemiparesis, who were treated at the stroke unit and participated in a 4-week rehabilitation program. Measurements of passive and active motion ranges were conducted with a goniometer in both limbs: healthy and affected ones by stroke. There were statistically significant differences in motion ranges between healthy and affected limbs. Examination I revealed that affected limbs amounted to only 40% of physiological range, while in Examination II, the result reached 73%. The most significant motion limitations were noted in terms of bending, adduction and internal rotation, while the least significant in terms of external rotation and abduction. Exercises used during early stroke rehabilitation of hemiparesis patients considerably increased active motion ranges and maintained passive motion ranges in the hip joint of the affected limb. Patients with right-sided hemiparesis experienced much better improvement in hip joint motion of the affected limb. The 4-week period was insufficient to mobilize patients and help them regain full active mobility in the hip joint of the affected limb. These patients required further physiotherapy, until they fully regained functionality.

Pedicle screw-based posterior dynamic stabilisation of the lumbar spine: in vitro cadaver investigation and a finite element study

Pedicle screw-based dynamic constructs either benefit from a dynamic (flexible) interconnecting rod or a dynamic (hinged) screw. Both types of systems have been reported in the literature. However, reports where the dynamic system is composed of two dynamic components, i.e. a dynamic (hinged) screw and a dynamic rod, are sparse. In this study, the biomechanical characteristics of a novel pedicle screw-based dynamic stabilisation system were investigated and compared with equivalent rigid and semi-rigid systems using in vitro testing and finite element modelling analysis. All stabilisation systems restored stability after decompression. A significant decrease in the range of motion was observed for the rigid system in all loadings. In the semi-rigid construct the range of motion was significantly less than the intact in extension, lateral bending and axial rotation loadings. There were no significant differences in motion between the intact spine and the spine treated with the dynamic system (P>0.05). The peak stress in screws was decreased when the stabilisation construct was equipped with dynamic rod and/or dynamic screws.

An in vivo kinematic comparison of dynamic lumbar stabilization to lumbar discectomy and posterior lumbar fusion using radiostereometric analysis

BackgroundBiomechanical studies have shown that dynamic stabilization restores the neutral zone and stabilizes the motion segment. Unfortunately, there are limitations to clinical measurement of lumbar motion segments when using routine radiographs. Radiostereometric analysis is a 3-dimensional technique and can measure the spinal motion segment more accurately than techniques using plain film radiographs. The purpose of this study was measure and compare the range of motion after dynamic stabilization, posterior lumbar fusion (PLF), and lumbar discectomy. MethodsFour patients who underwent lumbar decompression and dynamic stabilization (Dynesys; Zimmer Spine, Inc., Warsaw, Indiana) for treatment of lumbar spondylosis were compared with 4 patients with a similar diagnosis who were treated by PLF and pedicle screw fixation (PLF group) and 8 patients who had undergone lumbar microdiscectomy (discectomy group) for treatment of radiculopathy. During the surgical procedure, 3 to 5 tantalum beads were placed into each of the operative segments. The patients were followed up postoperatively at 1 month, 1 year, and 2 years. At each follow-up time point, segmental motions (flexion, extension, and total sagittal range of motion [SROM]) were measured by radiostereometric analysis. ResultsFlexion, extension, and SROM measured 1.0° ± 0.9°, 1.5° ± 1.3°, and 2.3° ± 1.2°, respectively, in the Dynesys group; 1.0° ± 0.6°, 1.1° ± 0.9°, and 1.5° ± 0.6°, respectively, in the PLF group; and 2.9° ± 2.4°, 2.3° ± 1.5°, and 4.7° ± 2.2°, respectively, in the discectomy group. No significant difference in motion was seen between the Dynesys and PLF groups or between the Dynesys and discectomy groups in extension. Significant differences in motions were seen between the PLF and discectomy groups and between the Dynesys and discectomy groups in flexion (P = .007) and SROM (P = .002). There was no significant change in the measured motions over time. ConclusionsIn this study a significantly lower amount of motion was seen after dynamic stabilization and PLF when compared with discectomy. A future study with a larger cohort is necessary to examine what effect, if any, these motions have on clinical outcomes.

Motion generated in the unstable cervical spine during the application and removal of cervical immobilization collars

Many studies have compared the restriction of motion that immobilization collars provide to the injured victim. No previous investigation has assessed the amount of motion that is generated during the fitting and removal process. The purpose of this study was to compare the three-dimensional motion generated when one-piece and two-piece cervical collars are applied and removed from cadavers intact and with unstable cervical spine injuries. Five fresh, lightly embalmed cadavers were tested three times each with either a one-piece or two-piece cervical collar in the supine position. Testing was performed in the intact state, following creation of a global ligamentous instability at C5-C6. The amount of angular motion resulting from the collar application and removal was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc., Colchester, VT). The measurements recorded in this investigation included maximum values for flexion/extension, axial rotation, medial/lateral flexion, anterior/posterior displacement, axial distraction, and medial/lateral displacement at the level of instability. There was statistically more motion observed with application or removal of either collar following the creation of a global instability. During application, there was a statistically significant difference in flexion/extension between the one-piece (1.8 degrees) and two-piece (2.6 degrees) collars, p = 0.009. There was also a statistically significant difference in anterior/posterior translation between the one-piece (3.6 mm) and two-piece (3.4 mm) collars, p = 0.015. The maximum angulation and displacement during the application of either collar was 3.4 degrees and 4.4 mm. Statistical analysis revealed no significant differences between the one-piece and two-piece collars during the removal process. The maximum angulation and displacement during removal of either collar type was 1.6 degrees and 2.9 mm. There were statistically significant differences in motion between the one-piece and two-piece collars during the application process, but it was only 1.2 degrees in flexion/extension and 0.2 mm in anterior/posterior translation. Overall, the greatest amount of angulation and displacement observed during collar application was 3.4 degrees and 4.4 mm. Although the exact amount of motion that could be deleterious to a cervical spine-injured patient is unknown, collars can be placed and removed with manual in-line stabilization without large displacements. Only trained practitioners should do so and with great care given that some motion in all planes does occur during the process.

Rigid Indian plate: Constraints from GPS measurements

We analyze GPS data from 26 sites located on the Indian plate and along its boundary. The large spatial coverage of the Indian plate by these sites and longer data duration helped us in refining the earlier estimates of the Euler pole for the Indian plate rotation. Our analysis suggests that the internal deformation of the Indian plate is very low (<1–2mm/year) and the entire plate interior region largely behaves as a rigid plate. Specifically, we did not infer any significant difference in motion on sites located north and south of the Narmada Son failed rift region, the most prominent tectonic feature within the Indian plate and a major source of earthquakes. Our analysis also constrains the motion across the Indo-Burmese wedge, Himalayan arc, and Shillong Plateau and Kopili fault in the NE India.

A Biomechanical Analysis of a Tensioned Suture Device in the Fixation of the Ligamentous Lisfranc Injury

We hypothesized that using a cadaveric Lisfranc ligamentous injury model, abduction stress would provoke greater post-injury motion than axial weightbearing between the medial cuneiform (MC1) and the base of the second metatarsal (MT2). Second, we hypothesized that both a tensioned suture-button device and a rigid screw fixation method could maintain a reduction and similarly restrain motion to intact (pre-injury) levels. Motion was measured between MC1 and MT2 in five matched pairs of human cadaveric feet. Specimens were tested prior to injury, following a transverse ligamentous Lisfranc injury, and then randomized to either screw or tensioned suture-button fixation. Axial then abduction loads were applied. Measurements were repeated after one thousand loading cycles. With both axial and abduction loads, statistically significant differences in motion were detected between the intact and post-injury conditions, although the magnitudes were greater with abduction (6.8 mm versus 2.0 mm, p = 0.000004). With abduction loads, both fixation methods were effective in restraining motion to pre-injury levels (screw fixation: 1.5 mm intact versus 1.1 mm post-fixation, p = 0.487; suture-button fixation: 1.3 mm intact versus 2.1 mm post-fixation, p = 0.063), and similarly, both devices restrained motion to less than post-injury levels (screw fixation: 8.1 mm post-injury versus 1.1 mm post-fixation, p = 0.001; suture-button fixation: mean 5.5 mm post-injury versus 2.1 mm post-fixation, p = 0.0002). No significant differences in these patterns were detected following cyclic loading. Small, though statistically significant, amounts of motion are produced between MC1 and MT2 with axial loading after a ligamentous Lisfranc injury. With abduction stress, we were able to show a significantly greater difference between pre- and post-injury motion and the ability of both fixation methods to restrain motion to pre-injury levels. Abduction stress may be valuable when diagnosing and testing the transverse ligamentous Lisfranc injury. Both suture-button and screw fixation methods restrain motion at the Lisfranc complex.

Clinical Impact of United Versus Nonunited Fractures of the Proximal Half of the Ulnar Styloid Following Volar Plate Fixation of the Distal Radius

Distal radius fractures are often associated with a fracture of the ulnar styloid at its base. This study tested the null hypothesis that there is no difference in outcome between patients with union and nonunion of a fracture of the proximal half of the ulnar styloid 6 months after volar plate fixation of a fracture of the distal radius. A total of 36 consecutive patients with fractures of both distal radius and the proximal half of the ulnar styloid enrolled in 1 of 2 clinical trials evaluating volar plate fixation of the distal radius had no treatment of the ulnar styloid fracture. Six months after surgery, wrist function was assessed using the Mayo wrist score and the Gartland and Werley score system, and arm-specific health status was measured using the Disabilities of the Arm, Shoulder, and Hand questionnaire. Pain was assessed on a 10-point ordinal scale. Nonunion of the fracture of the proximal half of the ulnar styloid was defined as no signs of consolidation on 6-month postoperative radiographs. At the 6-month follow-up, patients were assessed for overall wrist function but not specifically for ulnar-sided wrist problems or stability. Sixteen ulnar styloid fractures had united, and 20 had not. There were no differences in demographic and injury characteristics. There were no significant differences in motion; strength; Gartland and Werley scores; Mayo scores; Disabilities of the Arm, Shoulder, and Hand scores; or pain scores 6 months after fracture. Nonunion of a fracture of the proximal half of the ulnar styloid has no effect on wrist function, pain, and upper extremity-specific health status 6 months after volar plate fixation of a fracture of the distal radius. Therapeutic III.

Evaluating “Eee” Phonation in Multidetector CT of the Neck

Since the advent of pharyngography, "eee" phonation has been used to distend the airway during imaging. When imaging shifted to axial CT, "eee" phonation was used to delineate mucosal anatomy better. However, because patients could not phonate for the entire examination (which could take several minutes), the technique was only useful during supplemental imaging, performed after the primary acquisition through the neck. The supplemental images covered a limited area (usually the larynx or supraglottis) and, therefore, could be obtained while patients phonated. Imaging of the neck has now shifted to multidetector CT (MDCT). With a 64-detector MDCT, the entire neck can be imaged in 8 seconds. We evaluated whether "eee" phonation could be used during the entire acquisition through the neck without degrading image quality. Forty-eight patients who performed "eee" phonation during a CT examination of the neck were compared with 96 patients scanned following a breath-hold command. All patients were scanned on the same 64-detector MDCT scanner after intravenous contrast administration. Images were acquired at a 2-mm section thickness and reconstructed at 1-mm intervals. All scanning times ranged from 5 to 7 seconds. Studies were evaluated separately by 2 neuroradiologists for image degradation due to motion. Statistical analysis was performed by using the proportional odds ratio. We found no significant difference in motion during phonation compared with the breath-hold technique. Our results indicate that "eee" phonation can be performed during an entire image acquisition through the neck, when performed with the speed of the 64-detector scanner, without increasing motion.

Effect of lower two-level anterior cervical fusion on the superior adjacent level

Symptomatic multisegment disease is most common at the C5-6 and C6-7 levels, and two-level anterior cervical discectomy and fusion (ACDF) is performed most often at these levels. Therefore, it may be clinically important to know whether a C5-7 fusion affects the superior C4-5 segment. A biomechanical study was carried out using cadaveric cervical spine specimens to determine the effect of lower two-level anterior cervical fusion on intradiscal pressure and segmental motion at the superior adjacent vertebral level. Five cadaveric cervical spine specimens were used in this study. The specimens were stabilized at T-1 and loaded at C-3 to 15 degrees flexion, 10 degrees extension, and 10 degrees lateral bending before and after simulated two-level ACDF with plate placement at C5-7. Intradiscal pressure was recorded at the C4-5 level, and segmental motion was recorded from C-4 through C-7. Differences in mean intradiscal pressures were calculated and analyzed using a paired Student t-test. When the maximum calibrated intradiscal pressures were exceeded ("overshot") during measurements, data from the specimens involved were analyzed using the motion data with a Student t-test. Values for pressure and motion obtained before and after simulated ACDF were compared. During flexion, the mean intradiscal pressure changes (+/- standard deviations) in the pre- and post-ACDF measurements were 1275 (+/- 225) mm Hg and 2475 (+/- 75) mm Hg, respectively (p < 0.05). When the results of pre-ACDF testing were compared with post-ACDF results, no significant difference was found in the mean changes in the intradiscal pressure during extension and lateral bending. The maximum calibrated intradiscal pressures were exceeded during the post-ACDF testing in four specimens in extension, three in flexion, and two in lateral bending. Comparison of pre- and post-ACDF data for all five specimens revealed significant differences in motion and intradiscal pressure (p < 0.05) during flexion, significant differences in motion (p < 0.05) but not in intradiscal pressure during extension, and significant differences in intradiscal pressure changes (p < 0.05) but not in motion during lateral bending. Simulated C5-7 ACDF caused a significant increase in intradiscal pressure and segmental motion in the superior adjacent C4-5 level during physiological motion. The increased pressure and hypermobility might accelerate normal degenerative changes in the vertebral levels adjacent to the anterior cervical fusion.