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PubMed1999

Eustachian tube cartilage and medial movement of lateral pharyngeal wall on phonation.

Several authors have demonstrated the importance of medial movement of the lateral pharyngeal wall in velopharyngeal closure upon phonation. However, it remains controversial what muscle is responsible for lateral pharyngeal wall movement and where is the main site of this movement. The purpose of this study was to address the above two unanswered questions. In 22 subjects (12 normal volunteers, 10 patients with cleft palate), lateral pharyngeal wall movement upon phonation was evaluated by using rapid magnetic resonance imaging (MRI). Before rapid MRI, their lateral pharyngeal wall movements were classified into three groups: the poor, moderate, and good, according to the findings of nasopharyngoscopy. Inward displacement of the eustachian tube cartilages upon phonation, which was quantified as distance ratio in the transverse plane of MR images, was compared with nasopharyngoscopic findings. In addition, the level of lateral pharyngeal wall movement was observed in the plane 5 mm lateral to the mid-sagittal plane of MR images. Inward displacement of the eustachian tube cartilage in the transverse plane of MR images was coincident with medial movement of lateral pharyngeal wall observed by nasopharyngoscopy in all 22 subjects. By using one-way analysis of variance, a statistically significant correlation was found between nasopharyngoscopic classification and distance ratio. The sagittal plane of MR images revealed that the main site of movement occurred at the level of the hard palate and above. It is concluded that medial movement of the lateral pharyngeal wall consists of inward displacement of the eustachian tube cartilage, which is caused by contraction of the levator veli palatini muscle, and that the primary site of this movement is at the level of the hard palate and above, where the eustachian tube, but not the superior constrictor muscle, exists.

Adolescent↗
PubMed2001

Lateral intermuscular septum of the thigh and short head of the biceps femoris muscle: an anatomic investigation with new clinical applications.

An anatomic study was performed to reappraise the vasculature of the lateral intermuscular septum of the thigh and muscles associated with it using 12 preserved cadaver legs. Several possible new clinical applications of the lateral intermuscular septum and the short head of the biceps femoris were identified as follows: (1) short head of biceps femoris muscle or musculoseptal flap based on the second and/or third profunda perforating vessels, or based on the superior lateral genicular vessels, with or without the iliotibial tract and the deep fascia, and with or without the motor nerve of the short head; (2) transverse extension of the fascial portion of the tensor fasciae latae muscle or musculocutaneous flap to include the lateral intermuscular septum; (3) combination use of items 1 and 2, above; and (4) free septofascial graft using the lateral intermuscular septum and iliotibial tract. It is anticipated that the distally based short head of the biceps femoris muscle flap will be an additional option for repairing defects around the knee, and that a free short head of the biceps femoris muscle flap based on the profunda femoris perforating vessels will be useful in functional reconstruction such as reanimation of the paralyzed face. The lateral intermuscular septum can be incorporated into the short head of biceps femoris muscle flap or into the tensor fasciae latae flap, and it also can be used as a free fascial graft. Functional deficit resulting from harvesting the short head of the biceps femoris and the lateral intermuscular septum is minimal, and donor wound at the lateral lower thigh seems to be acceptable.

Adult↗
PubMed1996

Evaluation of cervical posterior lateral mass screw placement by oblique radiographs.

STUDY DESIGN: The present study analyzed the two-dimensional representation of cervical lateral mass screws by oblique radiographs compared with cadaveric placement. This was accomplished by posterior and lateral cervical dissection of the lateral masses and intervertebral foramina, keeping the emerging nerve roots intact. The intervertebral foramina were divided into two zones for the study. OBJECTIVES: To identify and describe the value of oblique radiographs in evaluating posterior lateral mass screw placement in the cervical spine. SUMMARY OF BACKGROUND DATA: Posterior plate-screw fixation is an effective method of stabilizing the traumatized cervical spine. Because of the surrounding anatomy, precise placement of screws must be attained to avoid iatrogenic injury to the nerve roots, and incorrectly placed screws must be identified quickly to minimize the neurologic complication. No previous radiologic study regarding evaluation of the lateral mass screw placement has been reported. METHODS: Six cervical spines were removed from embalmed cadavers. Posterior and lateral removal of soft tissue ensued until the lateral masses and spinal nerves were clearly and completely exposed. Two specimens and 20 screws were used for each of the following methods: Roy-Camille, zone 1 placement, and zone 2 placement. Zone 1 was defined as the area between pedicles of adjacent vertebrae. Zone 2 was defined as the area between transverse processes of adjacent vertebrae. Forty-five degrees oblique left and right, anteroposterior, and lateral radiographs were taken. RESULTS: All screws placed by the Roy-Camille technique and 19 of 20 screws intentionally placed in zone 1 were represented accurately by oblique radiographs. Nineteen of 20 screws placed in zone 1 were well appreciated in the foramen in oblique view. However, 13 of 20 screws placed in zone 2 and approximating the nerve root were inaccurately represented or ambiguous in oblique radiographs. CONCLUSIONS: Oblique radiographs are valuable to view the relationship between screw placement and foramina. Screws crossing the line connecting the posterior borders of the intervertebral foramina and appearing in the pedicle actually exit the bone and may risk damaging the nerve root.

Bone Screws↗
PubMed1996

The projection of the lateral sacral mass on the outer table of the posterior ilium.

STUDY DESIGN: This study was designed to construct the projection of the lateral sacral mass on the posterior ilium using cadaveric pelves and to measure the dimensions of the projection. OBJECTIVES: The present study was undertaken to determine quantitatively the location of the lateral sacral mass on the outer table of the ilium. SUMMARY OF BACKGROUND DATA: Anatomic studies relative to instrumentation of the posterior iliosacral region are few. No previous anatomic studies with regard to the projection of the lateral sacral mass have been reported. METHODS: Twelve cadaveric pelves were used for this study. To determine the projection of the lateral sacral mass on the outer table of the posterior ilium, several Kirschner wires were drilled along the outermost peripheral edge of the lateral sacral mass from the inner table of the ilium through the outer table. A triangle projection on the outer table of the posterior ilium was then constructed according to the placed Kirschner wires. The widths and height of the projection, and the distances from the axis of the projection to posterior superior iliac spine and posterior inferior iliac spine were measured bilaterally. RESULTS: The average height of the projection of the lateral sacral mass was 61.4 mm. The average base width of the projection was 56.8 mm. The average distances from posterior superior iliac spine and posterior interior iliac spine to the longitudinal axis of the projection of the lateral mass were 30 mm and 27.4 mm, respectively. CONCLUSIONS: This study reported the average location of the lateral sacral mass on the outer table of the ilium. The superior area of the projection may be an ideal zone for transiliosacral screw placement.

Adult↗
PubMed1998

Trunk muscle co-contraction increases during fatiguing, isometric, lateral bend exertions. Possible implications for spine stability.

STUDY DESIGN: Surface electromyographic activities were recorded from bilateral trunk muscles as test participants maintained a 50% maximum, voluntary, isometric, lateral bend contraction to volitional exhaustion. OBJECTIVES: To challenge the trunk with a prolonged lateral bend task and observe the responses of the agonist and antagonist muscles to the resulting fatigue. SUMMARY OF BACKGROUND DATA: Lateral bend exertions of the trunk have been identified as a risk factor for injury to spine tissues. However, little is known about the response of spine muscles to fatigue and the subsequent implications for spine stability, joint loading, and tissue injury. Surface electromyography provides a window on muscle loading and progressive fatigue. METHODS: Eleven male participants performed a set of maximum lateral bend exertions at the start of the trial, then maintained an upright standing posture while resisting 50% of the maximum moment until volitional exhaustion, then performed another set of maximum contractions. All contractions were isometric. Measurements were made, throughout each contraction, of the lateral bend moment and abdominal and trunk extensor electromyographic activities at six bilateral surface electromyography sites. Electromyographic amplitude and mean power frequency were calculated with 500-millisecond segments recorded serially every 800 milliseconds. Mean values were calculated with data from the first and last 5% of the trial durations. Statistics determined if fatigue had a significant effect on maximum moment and the electromyographic statistics for each muscle site. RESULTS: Fatigue resulted in a significant decrease in maximum lateral bend moment and increase in moment variability. Decreases in mean power frequency, indicating fatigue, were observed in three agonists (the trunk extensors) and one antagonist muscle. Unfatigued agonist electromyographic amplitudes correlated well with the mechanical advantage of muscles to generate lateral bend moments. Unfatigued antagonist activities were low except for the thoracic erector spinae. The agonists and antagonists demonstrated average increases of 17% and 8%, respectively, when pooled across muscles. Much of this change was predicted to have been associated with increases in co-contracting muscle forces. CONCLUSIONS: The trunk responded to a prolonged, lateral bend contraction by increasing co-contraction as agonist trunk muscles fatigued. It was proposed that the fatigue compromised neural coordination and that the co-contraction served to maintain spine stability.

Adult↗
PubMed2001

The in vivo dynamic response of the human spine to rapid lateral bend perturbation: effects of preload and step input magnitude.

STUDY DESIGN: A repeated measures design was used to determine the effects that combinations of two preloads and two added loads have on spine mechanics both before and during the response to the added load. OBJECTIVE: To investigate the effects of varying initial isometric and added step input load magnitudes on mechanical and electromyographic responses of the trunk during sudden loading that causes lateral bending moments. SUMMARY OF BACKGROUND DATA: Cocontractions of the antagonistic and agonistic muscles of the trunk are required for stability during loading of the spine. In several in vivo studies, it was observed that trunk muscle cocontraction serves a functional role before the application of unexpected or sudden loads. The response of agonistic and antagonistic trunk muscles to rapid lateral bend moments would provide further insight into the dynamic stability mechanisms of the spine. METHODS: In this study, 13 men maintained an upright standing posture while resisting the application of lateral bend moments produced by four different loading conditions comprising combinations of two preloads (5% or 15% of the maximum isometric lateral bend moment) and two added loads (20% or 30%). The preloading was used to develop different initial levels of trunk stiffness before the application of the added loads. The lateral bend moment and angular rotation of the trunk were measured, as well as the surface electromyogram amplitudes of the bilateral internal oblique, external oblique, rectus abdominus, lumbar erector spinae, and thoracic erector spinae muscles. Dependent measures were recorded during the steady state preload conditions, and peak values were recorded after the load was added. RESULTS: Higher added loads resulted in higher peak lateral bend rotations, and higher preloads resulted in lower rotations. The patterns of response were similar for the peak lateral bend moments and the electromyogram amplitudes from four of the five agonistic muscles. The thoracic erector spinae excepted, each of the other four muscles demonstrated larger responses in the agonistic muscles. However, all of the antagonistic muscles showed some increase in electromyogram activity in response to the added load. The thoracic erector spinae appeared to have the role of counteracting the flexor moments created by the abdominal muscles and the maintenance of spine stability. The agonistic external obliques and lumbar erector spinae had the largest responses to the added load. A comparison of the 35% loading conditions showed an increased response of the trunk to the 5% + 30% condition (with lower initial trunk stiffness), as compared with the 15% + 20% condition. CONCLUSIONS: The findings from this study show that higher levels of preactivation can serve to increase spine compression and trunk muscle stiffness, thereby attenuating the lateral displacements caused by rapid loading. Furthermore, antagonistic muscles were observed to respond rapidly to such perturbations with large increases in activation when preactivation and spine stability were low. The trunk muscles monitored all were larger, multisegmental muscles. The results from this study lend support to previous studies suggesting that the larger multisegmental muscles make a significant contribution to spinal stability.

Adult↗
PubMedDate not supplied

Dome osteotomy for posttraumatic cubitus varus: a surgical technique to avoid lateral condylar prominence.

The indication for surgery in most children with posttraumatic cubitus varus is the presence of an unsightly deformity. The function of the limb is generally not impaired. Lateral closing-wedge supracondylar osteotomy, although a widely used corrective procedure, tends to produce lateral condylar prominence, thus jeopardizing the cosmetic outcome. The authors used the dome supracondylar osteotomy, as described by Tien et al, as the corrective procedure for cubitus varus in 12 consecutive children. The average follow-up was 2.3 (range 1-4) years. The objective evaluation was done by one of the authors by measuring the pre- and postoperative lateral condylar prominence index, carrying angle, and the range of movement at the elbow. The patients and parents were also asked to self-assess the cosmetic outcome. There were seven excellent and five good results. None of the children showed a prominent lateral humeral condyle. Hypertrophic scar formation and ulnar neurapraxia were seen in one patient each. These results were comparable to the published results of lateral closing-wedge osteotomy in terms of correction of carrying angle and preservation of elbow motion and were superior to those of the lateral closing-wedge osteotomy in terms of the prominence of lateral humeral condyle, acceptability of the scar, and cosmesis. The authors offer independent verification of the observation that the technique of dome osteotomy as described by Tien et al for the correction of the posttraumatic cubitus varus is a simple, safe, and technically sound procedure that prevents the lateral condyle from becoming prominent and yields an excellent cosmetic outcome.

Adolescent↗
PubMed2003

A comparison between the prone and lateral position for performing a thoracoscopic anterior release and fusion for pediatric spinal deformity.

STUDY DESIGN: Retrospective review of all patients who had a single stage thoracoscopic anterior release and spine fusion followed by a posterior spinal fusion with posterior instrumentation. OBJECTIVE: To analyze the results and complications of patients undergoing a thoracoscopic anterior release and fusion comparing those performed prone with those in the lateral position. SUMMARY OF BACKGROUND DATA: The lateral position has traditionally been used when performing a thoracoscopic anterior spinal release and fusion during a single-stage anterior spinal release and fusion/posterior spinal fusion with instrumentation. Although some have reported the thoracoscopic technique in the prone position, there are no direct comparison studies between the prone and lateral position. METHODS: A retrospective review was performed of all patients who had a single stage thoracoscopic anterior spinal release and fusion and posterior spinal fusion with instrumentation from a single institution. The medical record was reviewed to determine demographic data, positioning of the patient, levels fused, anesthesia time, operative time, chest tube drainage, and complications. Radiographs were reviewed to determine preoperative curve magnitude and postoperative curve correction. The Student t test was used to compare groups and statistical significance was defined as P < 0.05. RESULTS: There were 16 patients in the prone group and 27 in the lateral group. Adolescent idiopathic scoliosis was the most common diagnosis in both groups. All patients had a single-stage thoracoscopic anterior spinal release and fusion/posterior spinal fusion with instrumentation. In the prone group, the patient was positioned prone on a Hall-Relton frame or roll (small patients) for both the anterior spinal release and fusion and posterior spinal fusion with instrumentation. There were no significant differences between the prone and lateral groups with respect to age, gender, height, weight, and curve magnitude (73.8 degrees vs. 71.5 degrees ). There were fewer fused anterior levels in the prone group (5.3 vs. 6.2) (P = 0.05). When analyzing parameters that reflect potential difficulties imposed by the prone position, there were no statistically significant differences noted between groups, although there was a trend toward less anterior operative time per disc (24.3 vs. 25.9 minutes/disc), greater blood loss/anterior disc level (33.5 vs. 26.8 cc/disc), greater total chest tube drainage (445 vs. 419 cc), and less days with the chest tube in place (2.2 vs. 2.3 days) for the prone group when compared to the lateral group. There were statistically significant differences between the prone and lateral groups with respect to anesthesia preparation time (42.8 vs. 64.8 minutes), delay between the completion of the anterior procedure and the start of the posterior procedure (11.8 vs. 69.5 minutes), and the incidence of complications related to the use of single-lung ventilation (0 vs. 14.8%)(P < 0.05). Patients in the prone group required less time on oxygen after surgery (34.8 vs. 51.6 hours) and were discharged home earlier (4.6 vs. 5.5 days) (P < 0.05). CONCLUSIONS: A thoracoscopic anterior spinal release and fusion in the prone position appears to achieve the same results as when performed in the lateral position for pediatric spinal deformity. The prone position saves time in the operating room due to decreasing the time needed by the anesthesiologists and the transition time between the anterior and posterior procedures. Potentially serious complications related to single-lung ventilation are avoided with bilateral-lung ventilation in the prone position.

Adolescent↗
PubMed2005

Cervical muscle response to head rotation in whiplash-type left lateral impacts.

STUDY DESIGN: Twenty healthy volunteers were subjected to left lateral impacts, randomly looking either left or right. OBJECTIVES: The purpose of this study is to determine the response of the cervical muscles to lateral impact whiplash-type perturbations when the head is rotated at the time of impact. SUMMARY OF BACKGROUND DATA: A previous study of left lateral impacts with head in neutral posture suggests that the burden of impact is borne primarily by the splenius capitis muscles. In order to improve automobile designs to prevent whiplash injury, we need to understand the response of the cervical muscles to whiplash-type perturbations in less-than-ideal conditions, such as when the head is rotated to the right and at the time of lateral impact. METHODS: Bilateral electromyograms of the sternocleidomastoids, trapezii, and splenii capitis were recorded. Triaxial accelerometers recorded the acceleration of the sled, torso, and head of the participant. RESULTS: For participants experiencing a left lateral impact, whether having the head rotated to the left or right at the time of impact, the muscle responses generally increased with increasing levels of acceleration (P < 0.05). The time of onset and peak electromyograph reading for most muscles progressively decreased with increasing acceleration. Overall, however, muscle responses were of low magnitude with the head rotated to the left or right. The sternocleidomastoid muscle responsible for head rotation (i.e., right sternocleidomastoid muscle when looking left) had a greater electromyograph response than its counterpart (P < 0.05). The contralateral splenius capitis and trapezius had the highest electromyograph responses. The remaining muscles showed similar levels of electromyograph responses, but even at the highest acceleration of 12.8 m/s, all generated less than 45% of their maximal voluntary contraction electromyograph reading. CONCLUSIONS: Compared to a lateral impact with the volunteer's head in the neutral position, a lateral impact with head rotation to either right or left may reduce the muscle response. Further studies are needed to determine whether or not head rotation at the time of lateral impact reduces overall injury risk.

Adult↗
PubMed2005

Quantitative anatomic evaluation of cervical lateral mass fixation with a comparison of the Roy-Camille and the Magerl screw techniques.

STUDY DESIGN: An anatomic and computed tomography (CT) study of the Roy-Camille and the Magerl techniques with quantitative comparison of the safety zones of the two surgical techniques. OBJECT: The purpose of this study was to compare quantitatively the safety zones of the Roy-Camille and the Magerl techniques as a function of the vertebral level from C3-C6. SUMMARY OF BACKGROUND DATA: The two most popular techniques for lateral mass screws are the Roy-Camille and the Magerl technique. Nerve roots, vertebral artery, facet joints, and the spinal cord are at risk during the placement of lateral mass screws. Several anatomic studies are reported, but there is no comparative and quantitative evaluation. The influence of the vertebral level was never reported. METHODS: Lateral mass screws were first implanted on four cervical spines according to the two surgical techniques. Screws were then extracted and their cavities filled with a blue casting medium. To determine the precise limits of each safety zone in the sagittal plane, the specimens were sectioned according to the sagittal angulation of the two screwing techniques. The correlations between the anatomic landmarks on the specimen and the anatomic landmarks on the CT scan were established. One hundred and sixty lateral mass screws were then implanted in 20 cervical spines from C3-C6. A CT was done before and after placing lateral mass screws. On the morphologic CT scan, we measured the sagittal safety angle (SSA) for each surgical technique and also performed a morphometry of lateral masses. On the control CT scan, we analyzed screws placement in relation to the sagittal safety zone. RESULTS: The mean SSA was 15.8 +/- 6.3 degrees for the Roy-Camille technique and 18.7 +/- 3.8 degrees for the Magerl technique, P < 0.005. With respect to the vertebral level, the Roy-Camille safety zone decreased from C3-C6 with a greater angulation at C3-C4 (20.4 +/- 4.7 degrees ) than at C5-C6 (11.6 +/- 4.3 degrees ), P < 0.001. Such variations were not observed for the Magerl technique, the SSA of which was 19.4 +/- 3.6 degrees at C5-C6 and 17.9 +/- 4 degrees at C3-C4, P < 0.01. Lateral masses became more elongated and thinner at the lower segment of the cervical spine with a C3-C4 height/thickness ratio = 1.1 +/- 0.3 and a C5-C6 height/thickness ratio = 1.3 +/- 0.2, P < 0.005. Roy-Camille screws (19%) were found out of the safety zone at C3-C4 whereas 37.5% were found outside at C5-C6, P < 0.05. We observed opposite results for Magerl screws with 38% screws out of the safety zone at C3-C4 and only 17.5% outside at C5-C6, P < 0.05. CONCLUSION: The Roy-Camille technique demonstrated a progressive decrease of its safety zone from C3-C6. At C5 and C6 there is a great probability to have a transarticular screw with a Roy-Camille screw. A similar variation was not observed for the Magerl technique. These anatomic results seem to be in relation with the morphologic variability of lateral masses from C3-C6 as demonstrated by an increase of the height/thickness ratio at the lower part of the cervical spine. According to these anatomic considerations and previously published biomechanical data, Roy-Camille technique appears to be the best option at C3 and C4. On the opposite at C5 and C6, the choice is more difficult considering that there is no biomechanical difference between the two techniques and that the Magerl technique is safer but a more demanding procedure.

Biomechanical Phenomena↗
PubMed2006

Kinematics of the cervical spine in lateral bending: in vivo three-dimensional analysis.

STUDY DESIGN: Kinematics of the cervical spine during lateral bending were investigated using a novel system of three-dimensional motion analysis. OBJECTIVES: To demonstrate in vivo intervertebral coupled motions of the cervical spine during lateral bending of the neck. SUMMARY OF BACKGROUND DATA: No previous studies have successfully documented in vivo three-dimensional intervertebral motions of the cervical spine during lateral bending. METHODS: Twelve healthy volunteers underwent three-dimensional magnetic resonance imaging (MRI) of the cervical spine in 7 positions with 10 degrees increments of lateral bending. Relative motions of the cervical spine were calculated automatically by superimposing a segmented three-dimensional-MRI of the vertebra in the neutral position over images of each position using volume registration. RESULTS: Mean maximum lateral bending of the cervical spine to one side was 1.6 degrees to 5.7 degrees at each level. Coupled axial rotation opposite to lateral bending was observed in the upper cervical levels (Oc-C1, 0.2 degrees ; C1-C2, 17.1 degrees ), while in the subaxial cervical levels, it was observed in the same direction as lateral bending except for at C7-T1. Coupled flexion-extension motion was small at all vertebral levels (<1.1 degrees). CONCLUSIONS: We succeeded in identifying in vivo coupled motions of the cervical spine in lateral bending for the first time.

Adult↗
PubMed2003

The horizontal dynamic of the medial and lateral canthus.

PURPOSE: To identify and quantify the horizontal dynamic movement of the medial and lateral canthus in subjects without previous eyelid surgery. METHODS: Prospective, experimental study. RESULTS: Seventy-two eyes in 36 normal subjects were studied. Frontal view lateral canthal movement with abduction of the globe averaged -0.4 mm (negative numbers mean the canthus moves in the opposite direction of the globe), with a range of -3.8 to 2.1. Profile view lateral canthal movement with abduction of the globe averaged 1.6 mm, with a range of -2.2 to 4.7 mm. Frontal view lateral canthal movement with adduction of the globe averaged -0.3 mm, with a range of -3.7 to 3.9 mm. Profile view lateral canthal movement with adduction of the globe averaged 0.5 mm, with a range of -2.4 to 3.9 mm. Frontal view medial canthal movement with abduction of the globe averaged -0.4 mm, with a range of -3.9 to 1.5 mm. Frontal view medial canthal movement with adduction of the globe averaged 0.1 mm, with a range of -5.2 to 4.6 mm. Intrasubject variation was observed for all measurements. CONCLUSIONS: The medial canthus and the lateral canthus are dynamic structures that move with horizontal eye movements in patients who have not undergone canthoplasty. The measured movement of the lateral canthus differed, based on the position from which the measurements were made, and was not always in the direction of the globe. The movement of the lateral canthus and the medial canthus differed on the right and left sides of the same subject.

Adolescent↗
PubMed2005

Effect of a lateral wedge on joint moments during gait in subjects with recurrent ankle sprain.

This study assessed the biomechanic effects of wearing a lateral wedge on the subtalar joint moment during gait in athletes with and without an unstable lateral ankle. A crossover design was applied whereby 50 collegiate males walked with two different wedges: a 0 degrees control wedge and a 6 degrees lateral wedge. We investigated frontal plane angles and moments at the subtalar joint and the knee joint, as well as ground reaction forces and center of pressure excursion. Moments were derived using a three-dimensional inverse dynamics model of the lower extremity. The 6 degrees lateral wedge significantly increased the subtalar joint valgus moment (P < 0.001) and reduced the knee joint varus moment (P < 0.001) when compared with no wedge. The differences between wedge conditions were associated with a laterally shifted location of the center of pressure during stance phase. However, there were diverse, sometimes reversed effects with the wedge among the athletes with an unstable lateral ankle. These results indicate that biomechanical indications and limitations of lateral wedges in unstable lateral ankles should be analyzed in more detail, possibly leading to new guidelines for the use of such foot orthoses.

Adult↗
PubMed2001

A homeobox gene, PRESSED FLOWER, regulates lateral axis-dependent development of Arabidopsis flowers.

It is postulated that the symmetric organization of plant lateral organs is based on two crossed axes, the abaxial-adaxial and the lateral axes. The PRESSED FLOWER (PRS) gene, the expression and function of which are dependent on the lateral axis, is reported in this study. In the prs mutant, growth of the lateral sepals is repressed, and although the size and shape of the abaxial and adaxial sepals are normal, the cell files at the lateral margins are missing. Double-mutant analyses showed that the PRS gene functions independently of the determinations of both floral organ identity and floral meristem size. The PRS gene, encoding a putative transcriptional factor with a homeodomain, was shown to be required for cell proliferation. PRS gene expression is spatially and temporally unique and is expressed in a restricted number of L1 cells at the lateral regions of flower primordia, floral organ primordia, and young leaf primordia. Our study strongly suggests that the PRS gene is involved in the molecular mechanism of lateral axis-dependent development of lateral organs in Arabidopsis.

Alleles↗
PubMed2006

An ex vivo comparison of three different gutta-percha cones when compacted at different temperatures: rheological considerations in relation to the filling of lateral canals.

AIM: To compare ex vivo the penetration of three brands of gutta-percha cones, compacted under a constant force and heated to different temperatures, into artificial lateral canals. METHODOLOGY: Resin blocks with simulated main canals, each having two lateral canals (C at 6.5 and A at 13 mm from the surface of the resin block), were selected. A gutta-percha cone, either Mynol MF, Hygenic MF or GT Tulsa 0.04 was compacted into each main canal for 5 s using a wire rod with a diameter of 0.7 mm soldered to the bottom of a metal cylinder, with a force of 2.7 kg at controlled temperatures of 37, 42, 47, 52, 60 degrees C. The penetration of each brand of gutta-percha into 60 lateral canals (10 at each temperature) was measured using a stereomicroscope. Statistical analysis was performed using the ANOVA, the Scheffè test and the t-test. RESULTS: None of the three brands of cones entered up to 0.1 mm within either lateral canal until a temperature of 47 degrees C was reached; at that temperature only Mynol cones (P < or = 0.05) penetrated in four of 10 A-level canals (mean 0.13 +/- 0.19 mm) and in all 10 C-level canals (mean 0.43 +/- 0.12 mm). The A-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.76 +/- 0.34 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.31 +/- 0.12 mm) and Hygenic cones (mean 0.11 +/- 0.08 mm). At 60 degrees C the Mynol cones (mean 1.93 +/- 0.34 mm) penetrated significantly more (P < or = 0.05) than the Tulsa cones (mean 0.86 +/- 0.22 mm) and Hygenic cones (mean 0.67 +/- 0.19 mm). The C-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.91 +/- 0.29 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.47 +/- 0.16 mm) and Hygenic cones (mean 0.46 +/- 0.15 mm), whilst no significant difference was found at 60 degrees C. CONCLUSIONS: When heated and compacted, the three gutta-percha cones penetrated the lateral canals to different degrees. They penetrated more than 0.43 mm into the lateral canals only at temperatures higher than 47 degrees C.

Dental Pulp Cavity↗
PubMedDate not supplied

Blood gas values during intermittent positive pressure ventilation and spontaneous ventilation in 160 anesthetized horses positioned in lateral or dorsal recumbency.

One hundred sixty horses were anesthetized with xylazine, guaifenesin, thiamylal, and halothane for elective soft tissue and orthopedic procedures. Horses were randomly assigned to one of four groups. Group 1 (n = 40): Horses positioned in lateral (LRG1; n = 20) or dorsal (DRG1; n = 20) recumbency breathed spontaneously throughout anesthesia. Group 2 (n = 40): Intermittent positive pressure ventilation (IPPV) was instituted throughout anesthesia in horses positioned in lateral (LRG2; n = 20) or dorsal (DRG2; n = 20) recumbency. Group 3 (n = 40): Horses positioned in lateral (LRG3; n = 20) or dorsal (DRG3; n = 20) recumbency breathed spontaneously for the first half of anesthesia and intermittent positive pressure ventilation was instituted for the second half of anesthesia. Group 4 (n = 40): Intermittent positive pressure ventilation was instituted for the first half of anesthesia in horses positioned in lateral (LRG4; n = 20) or dorsal (DRG4; n = 20) recumbency. Spontaneous ventilation (SV) occured for the second half of anesthesia. The mean time of anesthesia was not significantly different within or between groups. The mean time of SV and IPPV was not significantly different in groups 3 and 4. Variables analyzed included pH, PaCO2, PaO2, and P(A-a)O2 (calculated). Spontaneous ventilation resulted in significantly higher PaCO2 and P(A-a)O2 values and significantly lower PaO2 values in LRG1 and DRG1 horses compared with LRG2 and DRG2 horses. Intermittent positive pressure ventilation resulted in normocarbia and significantly lower P(A-a)O2 values in LRG2 and DRG2 horses. In LRG2 the PaO2 values significantly increased from 20 minutes after induction to the end of anesthesia. The PaO2 and P(A-a)O2 values were not significantly different from the beginning of anesthesia after IPPV in DRG2 or DRG3. The PaO2 values significantly decreased and the P(A-a)O2 values significantly increased after return to SV in horses in LRG4 and DRG4. The PaO2 values were lowest and the P(A-a)O2 values were highest in all horses positioned in dorsal recumbency compared with lateral recumbency and in SV horses compared with IPPV horses. The pH changes paralleled the changes in PaCO2. Blood gas values during right versus left lateral recumbency in all groups were also evaluated. The PaO2 values were significantly lower and the P(A-a)O2 values were significantly higher during SV in horses positioned in left lateral (LRLG1) compared with right lateral (LRRG1) recumbency.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia, Intravenous↗
PubMed2002

Development of a computerized method for identifying the posteroanterior and lateral views of chest radiographs by use of a template matching technique.

In picture archiving and communications systems (PACS) or digital archiving systems, the information on the posteroanterior (PA) and lateral views for chest radiographs is often not recorded or is recorded incorrectly. However, it is necessary to identify the PA or lateral view correctly and automatically for quantitative analysis of chest images for computer-aided diagnosis. Our purpose in this study was to develop a computerized method for correctly identifying either PA or lateral views of chest radiographs. Our approach is to examine the similarity of a chest image with templates that represent the average chest images of the PA or lateral view for various types of patients. By use of a template matching technique with nine template images for patients of different size in two steps, correlation values were obtained for determining whether a chest image is either a PA or a lateral view. The templates for PA and lateral views were prepared from 447 PA and 200 lateral chest images. For a validation test, this scheme was applied to 1,000 test images consisting of 500 PA and 500 lateral chest radiographs, which are different from training cases. In the first step, 924 (92.4%) of the cases were correctly identified by comparison of the correlation values obtained with the three templates for medium-size patients. In the second step, the correlation values with the six templates for small and large patients were compared, and all of the remaining unidentifiable cases were identified correctly.

Databases as Topic↗
PubMed1996

Intensity modulation optimization, lateral transport of radiation, and margins.

Intensity modulation provides greatly increased control, leading to superior dose distributions with a potential for improved clinical outcome. It also allows us to compensate for deviations from the expected patterns in dose distributions caused by the lateral transport of radiation. This is important not only to produce more homogeneous dose distributions in the target volume but also, more importantly, to allow a reduction in the margins for the penumbra and a corresponding reduction in the volume of normal tissue irradiated. Potentially, this would permit escalation of doses to higher levels and further improve local control for the same or lower normal tissue complications. The intensity-modulated treatment design process, regardless of the specific method used, involves the tracing of rays from the source of radiation through the target volume. Intensities of rays are adjusted iteratively in an attempt to produce a desired homogeneous dose within the target volume, while at the same time striving to maintain normal tissue exposure within the limits of tolerance. If the lateral transport of scattered radiation is ignored, as is commonly done because of the complexities of incorporating it, the resulting dose distribution within the target volume may be considerably different from the anticipated pattern. This would be particularly true if there are high gradients in fluence patterns within the field to shield a normal anatomic structure. Similarly, the lateral transport of radiation would lead to a dose deficit just inside the boundary of the planning target volume (PTV) and a dose excess just outside it. The conventional remedy to make up for the loss of dose near the boundaries, thereby ensuring complete coverage of the target volume, would be to employ a margin for the "penumbra." We demonstrate that, with intensity modulation, we have an important new tool to improve target coverage, namely an appropriate increase in fluence just inside the boundary. Most suitably, a combination of increased fluence and a smaller than conventional margin should be employed. We have used an iterative scheme to compensate for lateral transport in the intensity modulation optimization process. In each iteration, the intensity distribution is first designed ignoring lateral transport. At the end of each iteration, the dose distribution is calculated using a pencil beam convolution method, thereby incorporating lateral transport and revealing the deviations from the anticipated dose distribution caused by lateral transport. In the next iteration, ray intensities are further adjusted to rectify the deviations. In general, only a few iterations are needed to adequately account for the lateral transport of radiation. We have applied this method to intensity-modulated prostate treatment plans and demonstrate that this methodology allows the use of smaller margins, improves target dose homogeneity, and provides greater protection for normal tissues. We examine the variation of the magnitude of the gain from one patient to another. The methodology described in this paper has been introduced into routine clinical use.

Biophysical Phenomena↗