Lateral Excursion Research Articles

Electromyographic activity of the jaw muscles and mandibular kinematics in young adults with theoretically ideal dental occlusion: Reference values.

BackgroundA necessary step to use neuromuscular analysis as diagnostic tool is to establish normal reference values for the physiological range in a healthy population. Surface electromyographic (sEMG) activity of the jaw muscles and mandibular kinematics were measured in young adults with theoretically ideal dental occlusion to determine normal reference values during different tasks. Differences between the sexes were evaluated.Material and MethodsForty young adults (20 men, 20 women; mean age 22.8 ± 3.9 years) with theoretically ideal dental occlusion were selected using very restrictive criteria. sEMG activity of the anterior temporalis (AT), posterior temporalis, masseter (MA), and suprahyoid muscles were evaluated in the rest position and during swallowing, mastication, and clenching. Mandibular kinematics in the rest position and during maximum excursions were assessed. Asymmetry, activity, and torque indices and MA/AT ratios were calculated.ResultsFor all muscles, sEMG values were 1.01-3.57 µV at rest, 3.50-10.85 µV during swallowing, and 41.04-86.59 µV during mastication. During clenching, values were 230.08-243.55 µV for the AT and MA muscles. Mean total asymmetry, activity, and torque indices at rest were 20.34 %, -15.04 %, and 19.02 %, respectively; during clenching, these values were 6.14 %, -2.62 %, and 4.46 %. MA/AT ratios were near 1. Kinematic measurements during lateral excursion, protrusive and maximum opening were 7.54, 8.44, and 37.38 mm respectively; lateral mandibular shift was 1.41 mm; free way and lateral displacement at rest were 1.40 and 0.26 mm. Right MA activity during mastication and clenching was higher in men than women.ConclusionsReference values for sEMG activity and mandibular kinematics were determined. Some muscular asymmetry and torque were observed. Key words:Electromyography, masticatory muscles, kinesiography, jaw movements, normal dental occlusion, sexual dimorphism.

Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study.

PURPOSEThis study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant.MATERIALS AND METHODSFour metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated.RESULTSThe different schemes and excursive positions had impact on the peri-implant strains. At MI and 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected.CONCLUSIONThe peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains.

Medial Patellofemoral Ligament Reconstruction

Objectives:Recurrent patellofemoral dislocation is usually a multifactorial pathology. Different surgical techniques have been described according to the etiology of dislocation. In absence of a severe malalignment or an anatomical patellofemoral dysplasia, reconstruction of Medial Patello-femoral Ligament (MPFL) can restore the normal tracking of the patella, avoiding lateral excursion. The purpose of this study was to evaluate clinical results and complications in patients who underwent a MPFL reconstruction.Methods:We retrospectively evaluated 19 patients who underwent an anatomic MPFL reconstruction using autologous semitendinosus graft between 2007 and 2012. Exclusion criteria were patients with less than three years of follow-up and those with an associated procedure such as distal realignment or trochleoplasty. Clinical outcomes were measured using Kujala score and return to sport rate. We registered the postoperative complications and recurrence rate.Results:Nine patients were men and 10 women with a mean age of 25 years. Average follow-up was 5.8 years. Nine patients (47.4%) returned to their previous sport level, 8 (42.1%) changed to another sport or decreased their level and 2 (10.5%) were unable to practice any sports at all. Kujala score improvement was from 62.8 preoperative to 88.8 postoperative. One patient decreased the Kujala score. Eighty-nine percent of patients were satisfied with their outcome. One patient had a patellar fracture and four developed an arthrofibrosis and required mobilization under anesthesia. No recurrences were registered.Conclusion:Isolated MPFL reconstruction for recurrent patellofemoral dislocation is an effective alternative in absence of severe malalignment or anatomical dysplasia. Although no recurrences where registered at minimum 3-year follow-up, almost half of the patients were not able to return to their previous sport level.

Seismic performance of CFRP-confined circular high-strength concrete columns with high axial compression ratio

This paper presents an experimental investigation on the seismic performance of circular high-strength concrete (HSC) columns confined with carbon fiber-reinforced polymer (CFRP) composites. A total of eleven 1/2 scale columns were constructed of which nine were confined with CFRP wraps at potential plastic hinge regions. All columns were tested under combined high axial compression load and cyclic lateral displacement excursions. The primary variables of the tests were the axial compression load level, concrete strength, and the extent of the CFRP wrapping at the plastic hinge region. In order to evaluate the residual seismic capacity of CFRP-confined columns, three of the confined specimens were initially loaded to induce damage. The load was then removed after which the same columns were loaded to failure. The failure modes, hysteretic responses, energy dissipation and stiffness degradation characteristics, and the equivalent viscous damping ratios of the tested columns were then presented and interpreted. The test results showed that CFRP wraps applied at potential hinge regions resulted in significantly improved ductility and energy dissipation capacities of the columns even when tested under a high axial compression ratio. The plastic deformation capacity of the CFRP-confined columns was observed to decrease with an increase of axial compression ratio though. In addition, pre-damaged CFRP-confined columns may have insufficient residual seismic capacity due to the damage and failure in the unconfined regions under high axial compression load levels. Finally, empirical models of the degradation of effective and unloading stiffness are provided based on the test results.

Effect of subthalamic nucleus deep brain stimulation on balance in Parkinson’s disease: A static posturographic analysis

BackgroundThe effect of subthalamic deep brain stimulation on balance in Parkinson’s disease remains unclear. ObjectiveTo evaluate the effect of subthalamic nucleus stimulation on balance in Parkinson’s disease using posturography. Methods16 patients (9 women) who underwent subthalamic deep brain stimulation [mean age 59.6 years (46–70); mean disease duration 15.6 years (7–25); mean duration of subthalamic stimulation 32.1 months (3.0–69.6)] and 13 healthy age-matched controls were evaluated using a static posturography analysis. Patients were assessed under four conditions: 1) off medication/off stimulation; 2) off medication/on stimulation; 3) on medication/off stimulation and 4) on medication/on stimulation in ten experimental paradigms, some reproducing common situations of daily living. The displacement of the centre of pressure was analyzed using 14 posturographic parameters. The Mann-Whitney test was used to compare patients with controls. The Wilcoxon signed rank test was used to compare patients under different clinical conditions. ResultsPatients off medication/off stimulation showed larger and more rapid displacements of the centre of pressure than controls in most paradigms (p<0.05), particularly when performing a dual task. Subthalamic stimulation alone reduced the lateral excursion and anterior-posterior velocity of the centre of pressure in quite stance paradigms (p<0.05). Subthalamic stimulation combined with antiparkinsonian medication did not induce statistically significant changes in posturagraphic measures in any experimental paradigm. ConclusionsAlthough subthalamic stimulation alone may induce some positive effect on balance, subthalamic stimulation in addition to antiparkinsonian medication, which is the usual treatment in clinical practice, did not modify balance as assessed by static posturography in patients with Parkinson’s disease.

Digital workflow for a dental prosthesis that considers lateral mandibular relation

Most digital prosthesis designs consider only the maximal intercuspal position (MIP) and not the lateral movement. During the computer-aided design and computer-aided manufacture (CAD-CAM) prosthesis delivery process, the clinician has to adjust the prosthesis to avoid occlusal interference during lateral excursion. The novel digital workflow described in this report can be divided into 2 steps. After obtaining interocclusal records for the MIP and the lateral excursion position, the crown CAD data were designed using a general digital workflow considering only the MIP. The previous crown CAD data were then adjusted in the lateral excursion state before manufacturing the prosthesis. This process using information for 2 occlusal positions means that the definitive prosthesis design reflects not only static occlusion but also lateral mandibular relation.

Full Mouth Reconstruction of a Patient with Worn Dentition: A Clinical Report

The attrition of anterior teeth leads to the loss of efficient anterior guidance, which protects posterior teeth from wear during lateral excursions. This clinical report describes a 48-year-old man with diagonal tooth wear and posterior mandibular tooth loss. The clinical diagnosis was based on a complete oral examination, photos, functional analysis of lateral excursion movements, general health condition and behavioral aspects such as diet and bruxism. A mandibular partial overlay denture was used to reestablish the occlusal plane after the decision of restoring the vertical dimension of occlusion (OVD) by anatomical landmarks and physiological measurements. Once the compatibility of new OVD was approved and accepted, and followed for six months, fixed implant and tooth supported restorations were fabricated.A satisfactory clinical result was achieved by restoring OVD by 7 mm and avoiding advanced periodontal crown lengthening. Successful full mouth rehabilitation for a severely worn dentition can be achieved through good clinical management with long-term success to improve the quality of life.

Analysis of occupant kinematics and dynamics in nearside oblique impacts

ABSTRACTObjective: The objective of this article is to analyze the kinematics and dynamics of restrained postmortem human surrogates (PMHS) exposed to a nearside oblique impact and the injuries that were found after the tests.Methods: Three male PMHS of similar age (64 ± 4 years) and anthropometry (weight: 61 ± 9.6 kg; stature: 172 ± 2.7 cm) were exposed to a 30° nearside oblique impact at 34 km/h. The test fixture approximated the seating position of a front seat occupant. A rigid seat was designed to match the pelvic displacement in a vehicle seat. Surrogates were restrained by a 3-point seat belt consisting of a 2 kN pretensioner (PT), 4.5 kN force-limiting shoulder belt, and a 3.5 kN PT lap belt. The shoulder belt PT was not fired in one of the tests. Trajectories of the head, shoulder, and hip joint (bilaterally) were recorded at 1,000 Hz by a 3D motion capture system. The 3D acceleration and angular rate of the head, T1, and pelvis, and the 3D acceleration of selected spinal locations was measured at 10,000 Hz. Seat belt load cells measured the belt tension at 4 locations. PMHS donation and handling were performed with the approval of the relevant regional ethics review board.Results: Activation of the shoulder PT reduced substantially the peak forward excursion of the head but did not influence the lateral displacement of the head center of gravity (CG). In all 3 subjects, the lateral excursion of the head CG (291.1, 290, 292.1 mm) was greater than the forward displacement (271.4, 216.7, 171.5 mm). The hip joint excursion of the PMHS that was not exposed to the shoulder PT seat belt was twice the magnitude observed for the other 2 subjects. The 3 PMHS sustained clavicle fractures on the shoulder loaded by the seat belt and 2 of them were diagnosed atlantoaxial subluxation in the radiologist examination. Avulsion fractures of the right lamina of T1, T2, T3, and T4 were found when the PT was not used. The 3 PMHS received multiple fractures spread over both aspects of the rib cage and involving the posterior aspect of it.Conclusion: In this study of nearside oblique impact loading, the PMHS exhibited kinematics characterized by reduced torso pitching and increased lateral head excursion as compared to previous frontal impact results. These kinematics resulted in potential cervical and thoracic spinal injuries and in complete, displaced fractures of the lateral and posterior aspects of the rib cage. Though this is a limited number of subjects, it shows the necessity of further understanding of the kinematics of occupants exposed to this loading mode.

Protection of children in forward-facing child restraint systems during oblique side impact sled tests: Intrusion and tether effects

ABSTRACTObjective: Testing was conducted to quantify the kinematics, potential for head impact, and influence on head injury metrics for a center-seated Q3s in a forward-facing child restraint system (FFCRS) in oblique impacts. The influences of a tether and intruded door on these measures were explored.Methods: Nine lateral oblique sled tests were conducted on a convertible forward-facing child restraint seat (FFCRS). The FFCRSs were secured to a bench seat from a popular production small SUV at the center seating position utilizing the lower anchor and tether for children (LATCH). The vehicle seat was fixed on the sled carriage at 60° and 80° from full frontal (30° and 10° forward rotation from pure lateral) providing an oblique lateral acceleration to the Q3s and FFCRS. A structure simulating an intruded door was mounted to the near (left) side of vehicle seat. The sled input acceleration was the proposed FMVSS 213 lateral pulse scaled to a 35 km/h delta-V. Tests were conducted with and without the tether attached to the FFCRS.Results: Results indicate the influence of the tether on kinematics and injury measures in oblique side impact crashes for a center- or far-side-seated child occupant. All tests without a tether resulted in head contact with the simulated door, and 2 tests at the less oblique angle (80°) with a tether also resulted in head contact. No head-to-door contact was observed in 2 tests utilizing a tether. High-speed video analysis showed that the head moved beyond the CRS head side wings and made contact with the simulated intruded door. Head injury criterion (HIC) 15 median values were 589 without the tether vs. 332 with the tether attached. Tests utilizing a tether had less lateral head excursion than tests without a tether (median 400 vs. 442 mm).Conclusion: These tests demonstrate the important role of the tether in controlling head excursion for center- or far-side-seated child occupants in oblique side impact crashes and limiting the head injury potential with an intruded door. The tether may not influence the kinematics of a near-side-seated occupant as strongly where the vehicle door or side structure interacts with the CRS and influences its motion. The results indicate that there may be an opportunity to improve child head kinematics and head protection in oblique side impacts through different CRS attachment methods and/or alternative vehicle side structure protection or padding.

Quantitative evaluation of the occupant kinematic response of the THUMS 50th-percentile male model relative to PMHS laboratory rollover tests

ABSTRACTObjective: The objective of the current study was to evaluate the whole-body kinematic response of the Total Human Model for Safety (THUMS) occupant model in controlled laboratory rollover tests by comparing the model response to postmortem human surrogate (PMHS) kinematic response targets published in 2014.Methods: A computational model of the parametric vehicle buck environment was developed and the AM50 THUMS occupant model (Ver 4.01) was subjected to a pure dynamic roll at 360°/s in trailing-side front-row seating position.A baseline configuration was defined by a baseline posture representing the average of all PMHS postures, with a friction coefficient of 0.4 for the belt and 0.6 for the seat.To encompass challenges in controlling boundary conditions from the PMHS tests and ensure the robustness of the model evaluation, a total of 12 simulations were performed to investigate the following:1. The effect of initial posture by adding 3 additional postures representing PMHS extremes.2. The effect of belt tension by varying tension from the nominal vehicle retractor belt tension of 5 N to the 35 N belt tension used in the PMHS tests.3. The effect of friction between the environment (belt, seat) and THUMS.Trajectories (head, T1, T4, T10, L1, and sacrum), spinal segment rotations (head-to-T1, T1-to-T4, T4-to-T10, T10-to-L1, and L1-to-sacrum) relative to the rollover buck and spinal segment elongation/compression calculated from the simulations were compared to PMHS corridors using a correlation method (CORA).Results: THUMS baseline response showed lower correlation (overall CORA score = 0.63) with the PMHS response in rollover compared to other crash modes. THUMS and PMHS demonstrated similar kinematic responses in the longitudinal axis and vertical axis but significantly different lateral excursion relative to the seat. In addition, no spinal elongation was observed for THUMS compared to the PMHS.The posture, pretension, and belt frictions were found to alter model kinematics, especially on THUMS lateral axis motion. The posture was judged to be the most sensitive parameter evaluated because a change of 30 mm in the lateral axis results in up to an 80 mm of change in observed displacement.Conclusions: Though the model response in the lateral axis is significantly different than that of the PMHS, it is unclear whether this difference is the result of extrinsic factors (posture, pretension, and friction), where exact values in experiment are unknown or by model intrinsic factors (e.g., spine stiffness). These differences in occupant kinematics could potentially subject the PMHS and THUMS to very different loading conditions under roof impact in rollover crashes: different occupant posture and different roof impact location. Therefore, different injury mechanisms and severity might be predicted by the current model relative to the PMHS. Consequently, though the information provided in the current study could be useful for improving model biofidelity for rollover crashes, additional studies are required to properly solve this issue.

Frequency of temporomandibular disorder signs and symptoms among call center employees

Objective: The current study aimed to investigate the frequency of signs and symptoms of temporomandibular disorders (TMD) among call center employees.Methods: Workers from four call centers (CC) were invited to participate in this study. The examination was based on the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD). The tenderness of the masticator muscles was assessed on both sides by bilateral palpation. The mobility of the mandible was measured with a plastic millimeter ruler on opening, lateral excursions, and protrusion.Results: In total, 124 call center employees with a mean age of 28.61 ± 4.71 (between 22 and 47 years of age) were enrolled in this study. There was no statistically significant relation between the numbers of calls answered in a day and teeth clenching, teeth grinding, earache, tinnitus, or pain on yawning/chewing. Only protrusive movement pain and joint noise were significantly higher among employees who answered more than 140 calls/day (p < 0.01). An evaluation of the TMD signs and symptoms in relation to job stress level revealed that job stress level significantly affected the incidence of headaches among call center employees (p < 0.01).Conclusion: The present study demonstrated no statistically significant relation between TMD signs and symptoms and call center employees except protrusive movement pain and joint noise. This relation was seen only in the employees who answered more than 140 calls per day. Headache, teeth clenching, and TMJ noise were the signs and symptoms encountered most often in this study. Multicentered studies in different geographic locations should be conducted to eliminate the limitation of this study.

Temporomandibular joint chronic closed lock: Spontaneous resolution following surgical arthroscopy

PurposeThis study evaluated the efficacy of surgical arthroscopy in the management of patients with temporomandibular joint chronic closed lock. Patients and MethodsFifteen TMJs (Twelve patients) suffering anterior disc displacement without reduction and chronic closed lock were enrolled in the study. Arthroscopic lysis and lavage of the superior joint compartment was done under general anesthesia for all patients. ResultsThe results showed significant resolution of clinical signs and symptoms of TMJ chronic closed lock (pain and tenderness) and full restoration of normal range of motion (maximum interincisal opening, lateral excursions and protrusive movements) and regain of chewing ability. ConclusionTemporomandibular joint surgical arthroscopy is an effective and minimally invasive modality in treatment of TMJ closed lock.

Septic arthritis of the TMJ: a case report

ABSTRACT Septic arthritis of the temporomandibular joint (TMJ) is an uncommon condition; thus, reports in the specialized literature are still scarce. The TMJ may be affected by extension of a local infectious process, by post-traumatic hematoma, or secondarily, by hematogenous spread. Septic arthritis is more common in the large joints, with the knee and hip most frequently affected. It is characterized by insidious onset and a marked inflammatory process, and is monoarticular in 80% of cases. The present report describes the case of a 6-year-old boy with a history of rheumatoid arthritis who presented with pain, swelling, and redness in the right TMJ region, as well as limited jaw opening, closure, and lateral excursion bilaterally. The differential diagnosis and treatment of this rare clinical entity are described. Aspects concerning antibiotic therapy and imaging studies are also addressed.

Use of a backpack alters gait initiation of high school students

We assessed how backpack carriage influences the gait initiation (GI) process in high school students, who extensively use backpacks. GI involves different dynamics from gait itself, while the excessive use of backpacks can result in adverse effects. 117 high school students were evaluated in three experimental conditions: no backpack (NB), bilateral backpack (BB), and unilateral backpack (UB). Two force plates were used to acquire ground reaction forces (GRFs) and moments for each foot separately. Center of pressure (COP) scalar variables were extracted, and statistical parametric mapping analysis was performed over the entire COP/GRFs time series. GI anticipatory postural adjustments (APAs) were reduced and were faster in backpack conditions; medial–lateral COP excursion was smaller in this phase. The uneven distribution of the extra load in the UB condition led to a larger medial–lateral COP shift in the support-foot unloading phase, with a corresponding vertical GRF change that suggests a more pronounced unloading swing foot/loading support foot mechanism. The anterior–posterior GRFs were altered, but the COP was not. A possible explanation for these results may be the forward trunk lean and the center of mass proximity of the base of support boundary, which induced smaller and faster APA, increased swing foot/support foot weight transfer, and increased load transfer to the first step.

Kinematic analysis of mandibular motion before and after orthognathic surgery for skeletal Class III malocclusion: A pilot study

Objectives: The aim of the study was to detect the changes in 3D mandibular motion after orthognathic surgery for skeletal Class III malocclusion.Method: Using a 3D motion analyzer, free mandibular border movements were recorded in nine patients successfully treated for skeletal Class III malocclusion and in nine patients scheduled for orthognathic surgery. Data were compared using Mann–Whitney non-parametric U-test.Results: The results showed no differences between the groups in the total amount of mouth opening, protrusion, and in lateral excursions, but the percentage of mandibular movement explained by condylar translation was significantly increased after surgery (20% vs. 23.6%). During opening, the post-surgery patients showed a more symmetrical mandibular interincisal point and condylar path than pre-surgery patients (p < 0.01).Discussion: Patients treated with orthognathic surgery for skeletal Class III malocclusion recover a good and symmetric temporomandibular joint function.

Poster Abstracts

{Extract} The transition from swimming to walking was an important event in the evolution of tetrapods. To understand this transition, researchers have studied movement in many extinct and extant aquatic and semi-aquatic species. The epaulette shark Hemiscillum ocellatum uses slow-to-medium walking, fast walking, and swimming forms of aquatic locomotion. We described kinematic differences between the three gaits in neonate (n=6) and juvenile (n=6) sharks hatched and reared in the laboratory. Neonates retain nutrition from an internal yolk until they develop a consistent feeding schedule (~35d post-hatch). They are then classified as juveniles, foraging for worms, crustaceans, and small fish. We hypothesized that changes in diet and feeding habits would affect gait performance between neonates and juveniles. Using video tracking software and 13 anatomical landmarks along the fins, girdles, and body mid-line, whole body velocity, duty factor, fin frequency, girdle rotation, and body curvature were calculated to identify characteristic movements of the gaits for each shark. Velocity was greater in neonates when compared to juveniles across all gaits; however, both groups increased velocity from walking to swimming. Regardless of gait, pelvic girdles had a greater range of motion than pectoral girdles for both neonates and juveniles. In juveniles, regardless of gait, the contralateral sides of the pectoral and pelvic girdles were synchronized during lateral excursions. Neonates, however, exhibited overlapping of ipsilateral sides of the girdles. Understanding the transition from neonate to juvenile locomotory forms in this species could provide insight on the water to land transition of tetrapods.

Does Unilateral Temporomandibular Total Joint Reconstruction Result in Contralateral Joint Pain and Dysfunction?

The purpose of this study was to evaluate patients requiring unilateral total temporomandibular joint (TMJ) reconstruction and the risk for development of postsurgical contralateral TMJ pain and dysfunction over time requiring subsequent contralateral total joint reconstruction. Long-term subjective and objective outcomes of unilateral TMJ reconstruction also were evaluated. Seventy patients underwent unilateral total joint reconstruction using a patient-fitted total joint prosthesis from a single private practice from 1990 through 2012. The inclusion criteria were 1) unilateral TMJ reconstruction with TMJ Concepts or Techmedica patient-fitted total joint prosthesis; 2) operation performed by 1 surgeon (L.M.W.); 3) minimum 12-month follow-up; and 4) adequate records. There were no specific exclusion criteria. The primary outcome variable was to evaluate the effects of unilateral TMJ reconstruction with a total joint prosthesis on the contralateral TMJ relative to development of pain and dysfunction requiring subsequent contralateral reconstruction with a total joint prosthesis. Secondary outcome variables for all patients included TMJ pain, facial pain, headaches, diet, disability, quality of life, maximum incisal opening (MIO), and lateral excursion movements after unilateral TMJ reconstruction with the patient-fitted total joint prosthesis. Student t test and Wilcoxon test were used for statistical analyses, with a P value less than .01 for statistical significance. Sixty-one of 70 patients (87%) met the inclusion criteria (47 women [77%] and 14 men [23%]; average age, 38yr; age range, 11 to 69yr; average follow-up, 44months; range, 12 to 215months). Eight of 61 patients (13%) subsequently required contralateral TMJ reconstruction with a total joint prosthesis related to contralateral pain, dysfunction, and arthritis, but all 8 (8 of 27 [29.6%]) had previous contralateral TMJ disc repositioning surgery. For the secondary outcomes, TMJ pain decreased 63%, jaw function improved 61%, facial pain decreased 59%, headaches decreased 57%, diet improved 52%, disability decreased 58.5%, and MIO increased from 31.4 to 38.8mm (mean change, 7.4mm). All subjective factors and MIO showed statistically significant improvements at longest follow-up (P < .01). Patients requiring unilateral TMJ reconstruction with a patient-fitted total joint prosthesis have a strong probability of improving their clinical condition and do not require bilateral reconstruction if the contralateral TMJ is healthy. Patients with previous or concomitant contralateral TMJ surgery (articular disc repositioning) have an approximately 30% chance of requiring a total joint prosthesis in the future.

Gamma Knife radiosurgery in the treatment of abducens nerve schwannomas: a retrospective study.

OBJECTIVE Of the intracranial schwannomas, those arising from the vestibular nerves are the most common. Abducens nerve (AN) schwannomas are very rare, and there is limited literature on their optimal management. Therapeutic options include surgery and/or stereotactic radiosurgery. The aim of this study was to evaluate the role of Gamma Knife radiosurgery (GKRS) in these sixth cranial nerve (CN) schwannomas. METHODS The authors performed a retrospective analysis of patients who had undergone GKRS for intracranial tumors at their institute in the period from 2003 to 2010. Inclusion criteria were as follows: isolated AN paresis on presentation, a lesion along the course of the sixth CN, and imaging features characteristic of a schwannoma. Patients with other CN deficits and neurofibromatosis Type 2 were excluded. Symptomatic improvement was defined as the resolution of or an improvement in diplopia noted on a subjective basis or as an improvement in lateral eyeball excursion noted objectively on follow-up. A reduction in tumor volume by at least 20%, as noted by comparing the pre- and post-GKRS images, was deemed significant. RESULTS Six patients with a mean age of 37.1 years (range 17-55 years) underwent primary GKRS. There were 2 prepontine cistern, 3 cavernous sinus, and 1 cisterno-cavernous tumor. The mean duration of symptoms was 6.1 months (range 3-12 months). The mean tumor volume was 3.3 cm3 (range 1.5-4.8 cm3). The mean tumor margin radiation dose was 12.5 Gy (range 12-14 Gy), while the median margin dose was 12 Gy (50% isodose line). The median number of isocenters used was 5 (range 4-8). The brainstem received an average 8.35-Gy radiation dosage (range 5.5-11 Gy). The mean follow-up duration was 44.3 months (range 24-78 months). Symptoms remained stable in 1 patient, improved in 3, and resolved in 2 (total improvement 83%). Magnetic resonance imaging at the last follow-up showed a stable tumor size in 3 patients (50%) and a reduction in the other 3. Thus, the tumor control rate achieved was 100%. No new CN deficits were noted. CONCLUSIONS Abducens nerve schwannomas are rare intracranial tumors. They can be cavernous, cisternal, or cisterno-cavernous in location. Excellent tumor control rates and symptomatic improvement can be achieved with GKRS, which appears to be a safe and effective, minimally invasive modality for the treatment of such lesions. Therefore, it is reasonable to consider GKRS as the initial treatment of choice for this rare pathology. Long-term follow-up will be essential for further recommendations.

Management of Temporomandibular Joint Disorders by Arthroscopic Lavage

Introduction: Temporomandibular joint disorders (TMDs) are among the most common disorders in the maxillofacial region which usually present with joint pain, decreased jaw mobility, joint clicking, headache, tinnitus, neck pain etc. There are different modalities of treatment used for the TMDs. These include some conservative and surgical procedures. The main aim is to improve the jaw function and reduction of joint pain. Arthroscopy is a modern diagnostic and effective therapeutic procedure for the TMDs.&#x0D; Objective: To assess the outcome of arthroscopic lavage of Temporomandibular Joint (TMJ) in terms of improvement of jaw function and joint pain in patients suffering from TMDs.&#x0D; Materials and Methods: This prospective study was carried out at the department of Oral and Maxillofacial Surgery, Military Dental Centre, Combined Military Hospital of Dhaka Cantonment from 01 October 2014 to 31 March 2016. Patients were selected consecutively having TMDs and unresponsive to conservative nonsurgical therapy. Total thirty patients of TMDs were selected for study and all the patients were treated with arthroscopic lavage. Objective data were collected including, inter incisal opening, lateral excursion, deviation on opening, tenderness on palpation. A questionnaire in the form of visual analogue scale relating to pain, joint clicking and Jaw mobility were completed by each patient at 1 week,1 month and 6 months post operatively.&#x0D; Results: Among thirty patients, 10 patients were male and 20 patients were female. Mean age of the patient was 42.6±5.79 years. Maximum patients were in the age group of 41-45 years. There was statistically significant improvement in maximum incisal opening and pain score. There was also reduction in Joint clicking and tenderness in maximum patients.&#x0D; Conclusion: The findings of the present study suggested potential utility of arthroscopic lavage in the management of TMDs.&#x0D; Journal of Armed Forces Medical College Bangladesh Vol.12(1) 2016: 88-93

Temporomandibular Joint Ankylosis Can Be Successfully Treated With TMJ Concepts Patient-Fitted Total Joint Prosthesis and Autogenous Fat Grafts

To measure and identify factors associated with treatment outcomes for patients with temporomandibular joint (TMJ) ankylosis treated with TMJ Concepts patient-fitted total joint prostheses and autogenous fat grafts. This retrospective cohort study evaluated records of patients with TMJ ankylosis from a single private practice, treated from 1992 to 2011, who met the following inclusion criteria: 1) radiographic evidence of bony ankylosis, 2) limited incisal opening, 3) minimum of 12months' follow-up, and 4) treatment with TMJ Concepts (Ventura, CA)/Techmedica (Camarillo, CA) total joint prostheses and fat grafts. For each patient, the number of previous TMJ surgical procedures, as well as the estimated age of ankylosis onset, age at surgery, and length of postoperative follow-up, was recorded. Subjective evaluations were made with Likert-like scales (from 0 to 10) for 1) TMJ pain, 2) headache and facial pain, 3) jaw function, 4) diet, and 5) disability. Objective evaluations included maximal incisal opening and excursion movements. Nonparametric statistics were used for analysis. There were 32 patients (22 female and 10 male patients) with 48 ankylosed TMJs (16 bilateral and 16 unilateral) in this study, with a mean age of 39years (range, 11 to 68years), 2 or more previous TMJ surgical procedures in 69%, and a mean follow-up period of 68months (range, 12 to 168months). Trauma was the major etiology of TMJ ankylosis, occurring in 17 of 32 patients (53%). The following improvements occurred: The median value for TMJ pain changed from 8.0 preoperatively to 1.5 at longest follow-up; headache, from 8 to 3.5; facial pain, from 8 to 4; jaw function, from 8 to 2.5; diet, from 7 to 3; and disability, from 7 to 1.5. The median incisal opening was 14.5mm (interquartile range, 6.3 to 20mm) preoperatively and 35mm (interquartile range, 30 to 40mm) at longest follow-up. The median left lateral excursion improved from 0.5 to 2mm, and the median right lateral excursion improved from 1 to 1.3mm. All of these improvements were highly significant (P < .001, Wilcoxon tests). Equally favorable outcomes were found in patients with 12 to 48months of maximal follow-up and patients with more than 48months of maximal follow-up. The treatment of TMJ ankylosis with the TMJ Concepts patient-fitted total joint prosthesis in combination with fat grafting around the articulation area of the prosthesis is a viable and predictable method for improving pain levels, function, and quality of life, as well as prevention of reankylosis of the TMJ.