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PubMed2004

Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.

BACKGROUND: Although many investigators have evaluated the accuracy of ultrasonography and magnetic resonance imaging for the detection of full and partial-thickness rotator cuff tears, few have directly compared the two tests. The purpose of our study was to compare the accuracy of the two tests for detection and measurement of the size of rotator cuff tears, with arthroscopic findings used as the standard. METHODS: One hundred and twenty-four consecutive patients with shoulder pain were prospectively studied with ultrasonography and magnetic resonance imaging. Seventy-one had subsequent arthroscopy, and they formed the study group. The arthroscopic diagnosis was a full-thickness tear in forty-six patients, a partial-thickness tear in nineteen, and no tear in six. The presence or absence of a full or partial-thickness tear and the tear size as demonstrated by each imaging test and at the time of arthroscopy were recorded. The findings of the imaging tests and arthroscopy were then compared for each parameter. RESULTS: Ultrasonography correctly identified forty-five of the forty-six full-thickness tears and magnetic resonance imaging, all forty-six. Ultrasonography correctly identified thirteen of the nineteen partial-thickness rotator cuff tears and magnetic resonance imaging, twelve of the nineteen. The overall accuracy for both imaging tests was 87%. Ultrasonography correctly predicted the degree of retraction of 73% of the full-thickness tears and the length of 85% of the partial-thickness tears, and magnetic resonance imaging correctly predicted the retraction and length of 63% and 75%, respectively. Ultrasonography correctly predicted the width of 87% of the full-thickness tears and 54% of the partial-thickness tears, and magnetic resonance imaging correctly predicted the width of 80% and 75%, respectively. No significant differences between ultrasonography and magnetic resonance imaging were demonstrated (p > 0.05). CONCLUSIONS: Ultrasonography and magnetic resonance imaging had comparable accuracy for identifying and measuring the size of full-thickness and partial-thickness rotator cuff tears. When an investigator has comparable experience with both imaging tests, the decision regarding which test to perform for rotator cuff assessment does not need to be based on accuracy concerns. The choice can be based on other factors, such as the importance of ancillary clinical information (regarding lesions of the glenoid labrum, joint capsule, or surrounding muscle or bone), the presence of an implanted device, patient tolerance, and cost.

Adult↗

PubMed1997

Specimen preparation and quantification of collagen birefringence in unstained sections of articular cartilage using image analysis and polarizing light microscopy.

To establish an optimal method for analysis of the collagen structures from unstained tissue sections, a computerized image analysis system using a charge coupled device camera coupled to a polarizing light microscope was used. Retardation values of birefringence, which are proportional to the content and fibril orientation of collagen in the extracellular matrix of articular cartilage, were determined from sections prepared in different ways. In the superficial zone of articular cartilage, the highest retardation values were recorded from sections cut parallel to the so-called split lines indicating the anisotropic arrangement of collagen. Complete digestion of glycosaminoglycans reduced the retardation value by approximately 6.0%, suggesting a minor, but not insignificant, contribution of glycosaminoglycans to the birefringence of the matrix. The use of a mounting medium with a refractive index close to that of the collagen (e.g. DPX) increased the specificity of the method, since the optical anisotropy of collagen derives predominantly from the intrinsic (structural) birefringence. In conclusion, analysis of unstained sections after careful removal of paraffin and glycosaminoglycans from the tissues provides a sensitive and rapid quantitative assessment of oriented collagen structures in articular cartilage.

Animals↗

PubMed2007

Quantification of lumbar stability by using 2 different abdominal activation strategies.

OBJECTIVE: To determine whether the abdominal hollowing technique is more effective for lumbar spine stabilization than a full abdominal muscle cocontraction. DESIGN: Within-subject, repeated-measures analysis of variance was used to examine the effect of combining each of 4 loading conditions with either the hollow or brace condition on the dependent variables of stability and compression. A simulation was also conducted to assess the outcome of a person activating just the transversus abdominis during the hollow. SETTING: Laboratory. PARTICIPANTS: Eight healthy men (age range, 20-33y). INTERVENTIONS: Electromyography and spine kinematics were recorded during an abdominal brace and a hollow while supporting either a bilateral or asymmetric weight in the hands. MAIN OUTCOME MEASURES: Spine stability index and lumbar compression were calculated. RESULTS: In the simulation "ideal case," the brace technique improved stability by 32%, with a 15% increase in lumbar compression. The transversus abdominis contributed .14% of stability to the brace pattern with a less than 0.1% decrease in compression. CONCLUSIONS: Whatever the benefit underlying low-load transversus abdominis activation training, it is unlikely to be mechanical. There seems to be no mechanical rationale for using an abdominal hollow, or the transversus abdominis, to enhance stability. Bracing creates patterns that better enhance stability.

Abdominal Muscles↗

PubMed2004

Computer-aided quantification of focal cartilage lesions of osteoarthritic knee using MRI.

Noninvasive assessment of articular cartilage using magnetic resonance imaging (MRI) has gained popularity in the diagnosis of osteoarthritis (OA), a condition that affects 20 million Americans. Focal cartilage lesions, a defect found in roughly 19% of the OA population, currently can only be evaluated with confidence using minimally invasive arthroscopy. This article presents a computer-aided procedure using MRI to quantify focal cartilage lesions and aims to support clinical practices of diagnosis and monitoring of lesion progress. Upon a local minima search for identifying focal lesions, the proposed gradient peak method outlines lesion boundaries and then generates morphological properties, such as lesion volume and lesion area. The procedure was evaluated using simulated and in vivo data. First, a simulated lesion was created and analyzed, and the results were compared with the exact solutions. Second, an in vivo evaluation was carried out on seven human knees in which nine focal lesions were identified and quantified. Three of the subjects had follow-up analyses, at either 1 or 2 years. Finally, in an attempt to characterize local biochemical changes underlying focal lesions, MR-derived T2 values of defective cartilage within the lesion boundaries were examined and compared with the values of adjacent cartilage compartments.

Aged↗

PubMed2000

Knee instability after injury to the anterior cruciate ligament. Quantification of the Lachman test.

We have measured anterior and posterior displacement in 563 normal knees and 487 knees with chronic deficiency of the anterior cruciate ligament (ACL). We performed stress radiography using a simple apparatus which maintained the knee at 20 degrees of flexion while a 9 kg load was applied. There was no significant difference in posterior translation dependent on the condition of the ACL. Measurement of anterior translation in the medial compartment proved to be more reliable than in the lateral compartment for the diagnosis of rupture of the ACL, with better specificity, sensitivity and predictive values. We have classified anterior laxity based on the differential anterior translation of the medial compartment and identified four grades in each of which we can further distinguish four subgrades for laxity of the lateral compartment. Within each of these subgroups, either internal or external rotation may dominate and sometimes there is a major translation of both compartments. Radiological evaluation of displacement of the knee in 20 degrees of flexion provides conclusive evidence of rupture of the ACL. A detailed study of pathological displacement is the basis for a classification of laxity. It is then possible to decide for each type of laxity, the surgical treatment which is specifically adapted to the lesion, and to define a reference value for judging outcome.

Adolescent↗

PubMed1996

Quantification of articular cartilage in the knee with three-dimensional MR imaging.

RATIONALE AND OBJECTIVES: To determine the volume of articular cartilage in cadavers, patients, and healthy volunteers by using a volumetric, fat-suppressed spoiled gradient-recalled signal acquisition in the steady state (SPGR) magnetic resonance (MR) sequence. METHODS: Sagittal MR images were obtained with a fat-suppressed SPGR sequence (repetition time, 52 msec; echo time, 10 msec; 60 degrees flip angle; 3.0-3.5-mm partitions, 256 x 192 matrix, two signals acquired). The cartilaginous surfaces of the tibia, femur, and patella were planimetrically defined with a three-dimensional workstation. A three-dimensional model volume was created by threshold segmenting the cartilage from the adjacent tissues. The volume as calculated by using MR imaging was compared with the actual volume of the cartilage specimens. RESULTS: Observed measurements correlated with actual weight and volume displacement measurements with an accuracy of 82%-99% and linear correlation coefficients of 0.99 (P = 2.5e-15) and 0.99 (P = 4.4e-15). Precision of segmentation in healthy volunteers yielded a coefficient of variation of 0.4% for interobserver variability and 0.3% for intraobserver variability. CONCLUSION: This pilot study suggests that accurate volumetric calculations of knee articular cartilage are possible with currently available MR imaging pulse sequences and a commercially available work station.

Adult↗

PubMed2002

Wartenberg pendulum test: objective quantification of muscle tone in children with spastic diplegia undergoing selective dorsal rhizotomy.

The aim of this study was to investigate the reliability and sensitivity of the Wartenberg pendulum test for quantification of muscle tone in young children with spastic diplegia undergoing selective dorsal rhizotomy (SDR). Fourteen nondisabled children (mean age of 5.5 years, age range 2.3 to 8.8 years, one female and one male in each year) were tested twice. Twenty children with spastic diplegia (12 males, eight females; mean age of 4.3 years, age range 2.5 to 6.3 years) consecutively selected for SDR, were assessed before and 6 months after SDR. Parameters of the pendulum test: R2, R1, maximal velocity, and swing time were correlated with clinical assessments for spasticity (modified Ashworth scale, quadriceps reflex) and measurements of gross motor function: the Gross Motor Function Classification System and the Gross Motor Function Measure. The Wartenberg pendulum test was found to be an objective and sensitive method for quantifying spasticity in knee extensor muscles in children as young as 2.5 years old. The method was responsive to changes after SDR. The only correlation with clinical measurements of spasticity was between the R2 ratio and the quadriceps reflex. Swing time was the most reliable and sensitive variable; it showed a weak correlation with measurements for gross motor function.

Cerebral Palsy↗

PubMed2000

Quantification of measurement of femoral head coverage and Norberg angle within and among four breeds of dogs.

OBJECTIVE: To report values for percentage coverage of the femoral head (PC) and Norberg angle (NA) in 4 common breeds of dogs and to determine values for each that distinguish between normal and dysplastic hip status on the basis of Orthopedic Foundation for Animals (OFA) hip evaluation. ANIMALS: 1,841 dogs 24 to 48 months of age that were Labrador Retrievers (455), Golden Retrievers (423), Rottweilers (545), or German Shepherd Dogs (418). PROCEDURE: Retrospective analysis of NA and PC measured from standard OFA ventrodorsal pelvic radiographs from 4 breeds of dog. RESULTS: Norberg angle ranged from 67.4 to 124.4 degrees for Labrador Retrievers, 59.7 to 128.6 degrees for Rottweilers, 70.2 to 119.4 degrees for Golden Retrievers, and 55.3 to 121.3 degrees for German Shepherd Dogs. The PC ranged from 6.5 to 79.9% for Labrador Retrievers, 5.7 to 79.5% for Rottweilers, 8.3 to 79.3% for Golden Retrievers, and 5.4 to 83.7% for German Shepherd Dogs. On the basis of logistic regression modeling for determining normal versus abnormal hip status for all 4 breeds, cutoff points for NA were <105 degrees and PC were <50%. CONCLUSIONS AND CLINICAL RELEVANCE: Results of our study indicate that cutoff points of NA of 105 degrees and PC of 50% do not differentiate normal versus dysplastic hip status. Each of the 4 breeds had different values for NA and PC that distinguished normal from dysplastic hip status.

Animals↗

PubMed1999

Quantification of intact quadriceps tendon, quadriceps tendon insertion, and suprapatellar fat pad: MR arthrography, anatomy, and cryosections in the sagittal plane.

OBJECTIVE: The purpose of this study was to quantify quadriceps tendon length, thickness, and insertion in relation to the suprapatellar fat pad. SUBJECTS AND METHODS: We used three methods to analyze the anatomy of intact quadriceps tendons and insertions into the patellar base: MR arthrography (53 knees with intact extensor mechanisms), gross anatomy (16 cadaveric knees), and cryosections (four cadaveric knees). With an electronic cursor, two observers independently quantified the extensor mechanism on midline sagittal T1-weighted spin-echo sequences acquired on a low-field-strength (0.23 T) scanner. RESULTS: On MR arthrograms, quadriceps tendon length, determined from the superior patellar pole to the most superior part of the suprapatellar recess, measured 49 +/- 7 mm in women and 50 +/- 9 mm in men. Thickness of quadriceps tendon at three sites (suprapatellar recess, center, and superior patellar pole) measured 7 +/- 1 mm in women and 8 +/- 1 mm in men. Thickness was significantly larger in men at all measurement locations. Quadriceps tendon insertion and the suprapatellar fat pad along the patellar base measured 16 +/- 2 and 6 +/- 2 mm, respectively, in women, and 18 +/- 3 and 7 +/- 2 mm, respectively, in men. CONCLUSION: On midline MR images, sagittal thickness of the quadriceps tendon and its insertion was significantly larger in men than in women. The prevalence of the suprapatellar fat pad was 100%.

Adipose Tissue↗

PubMed2005

Calculating the 2D motion of lumbar vertebrae using splines.

In this study we investigate the use of splines and the ICP method [Besl, P., McKay, N., 1992. A method for registration of 3d shapes. IEEE Transactions on Pattern Analysis and Machine Intelligence 14, 239-256.] for calculating the transformation parameters for a rigid body undergoing planar motion parallel to the image plane. We demonstrate the efficacy of the method by estimating the finite centre of rotation and angle of rotation from lateral flexion/extension radiographs of the lumbar spine. In an in vitro error study, the method displayed an average error of rotation of 0.44 +/- 0.45 degrees, and an average error in FCR calculation of 7.6 +/- 8.5 mm. The method was shown to be superior to that of Crisco et al. [Two-dimensional rigid-body kinematics using image contour registration. Journal of Biomechanics 28(1), 119-124.] and Brinckmann et al. [Quantification of overload injuries of the thoracolumbar spine in persons exposed to heavy physical exertions or vibration at the workplace: Part i - the shape of vertebrae and intervertebral discs - study of a yound, healthy population and a middle-aged control group. Clinical Biomechanics Supplement 1, S5-S83.] for the tests performed here. In general, we believe the use of splines to represent planar shapes to be superior to using digitised curves or landmarks for several reasons. First, with appropriate software, splines require less effort to define and are a compact representation, with most vertebra outlines using less than 30 control points. Second, splines are inherently sub-pixel representations of curves, even if the control points are limited to pixel resolutions. Third, there is a well-defined method (the ICP algorithm) for registering shapes represented as splines. Finally, like digitised curves, splines are able to represent a large class of shapes with little effort, but reduce potential segmentation errors from two dimensions (parallel and perpendicular to the image gradient) to just one (parallel to the image gradient). We have developed an application for performing all the necessary computations which can be downloaded from http://www.claritysmart.com.

Algorithms↗

PubMed2000

Total power output generated during dynamic knee extensor exercise at different contraction frequencies.

A novel approach has been developed for the quantification of total mechanical power output produced by an isolated, well-defined muscle group during dynamic exercise in humans at different contraction frequencies. The calculation of total power output comprises the external power delivered to the ergometer (i.e., the external power output setting of the ergometer) and the "internal" power generated to overcome inertial and gravitational forces related to movement of the lower limb. Total power output was determined at contraction frequencies of 60 and 100 rpm. At 60 rpm, the internal power was 18+/- 1 W (range: 16-19 W) at external power outputs that ranged between 0 and 50 W. This was less (P<0.05) than the internal power of 33+/-2 W (27-38 W) at 100 rpm at 0-50 W. Moreover, at 100 rpm, internal power was lower (P<0.05) at the higher external power outputs. Pulmonary oxygen uptake was observed to be greater (P<0.05) at 100 than at 60 rpm at comparable total power outputs, suggesting that mechanical efficiency is lower at 100 rpm. Thus a method was developed that allowed accurate determination of the total power output during exercise generated by an isolated muscle group at different contraction frequencies.

Adult↗

PubMed1992

Accuracy of quantification of mandibular condyle displacement in digitally subtracted linear tomograms.

Using a TMJ skeletal phantom, we assessed validity and reliability of digitally subtracted linear tomographic images to quantify condylar position changes. Horizontally corrected frontal and lateral tomographic images were made with the condyle in a 'centred' position and displaced by 1, 2 and 3 mm increments in two of three directions (inferior, and posterior, or lateral). Film images were sequentially subtracted and then randomized so that observers were blinded to the amount and direction of condylar movement. Averages of three measurements of the dark bands representing condylar shifts were made using a digitizing tablet. The study utilized a nested design where the series of film images was subtracted twice and each subtraction was read twice by two examiners. We repeated the study with a second series of films treated in an identical manner. Average differences from expected values were similar for frontal and lateral techniques and all directions and increments of displacement. Typical average difference for any increment was less than 0.1 mm. Standard deviations in measures were similar across techniques and increments and were typically less than 0.1 mm. Significant variation in the absolute value of differences between measured and expected values by direction of condylar displacement was attributed to greater accuracy of registration on the vertical axis for frontal images. A significant source of variation in the study design element 'film set' was attributed to errors in repositioning the phantom.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed2005

Anterior tibial subluxation in anterior cruciate ligament-deficient knees: quantification using magnetic resonance imaging.

PURPOSE: The purpose of this study was to quantify anterior tibial subluxation (ATS) at full extension in patients with anterior cruciate ligament (ACL) deficiency using magnetic resonance imaging (MRI), and to elucidate the relation of ATS to the duration of ACL deficiency and the extent of anterior instability. TYPE OF STUDY: Retrospective case series study. METHODS: Ninety-six patients with isolated ACL deficiency and no history of injury in the contralateral knee were studied. We used thick-sliced T1-weighted sagittal MRI to quantify ATS at full extension. To measure ATS, MRIs were loaded into a personal computer, and the contour of the unaffected knee was compared with the affected knee using Photoshop software (Adobe, San Jose, CA). Anterior instability was measured using a KT-1000 arthrometer (MedMetric, Inc, San Diego, CA). RESULTS: The extent of ATS in 96 ACL-deficient knees was 2.1 +/- 1.3 mm (mean +/- SD) and the range was 0 to 4.6 mm. ATS was correlated positively with the duration of ACL deficiency and the extent of anterior instability. CONCLUSIONS: In ACL-deficient knees, tibiofemoral kinematics differ from a normal knee without external force. The extent increases with time and is positively correlated with instability. CLINICAL RELEVANCE: In ACL reconstruction for patients with a long history or gross instability, when the location of tibial bone tunnel is determined, tibial reference points are more reliable than femoral reference points because the femur shifts relative to the tibia.

Adolescent↗

PubMed2001

Quantification of laser-induced cartilage injury by confocal microscopy in an ex vivo model.

BACKGROUND: The application of lasers in orthopaedic surgery is increasing. However, some investigators have reported that osteonecrosis may occur after laser meniscectomy. The objective of the present study was to evaluate the effect of laser wavelength and energy on cartilage injury in an ex vivo model. METHODS: Fresh bovine articular cartilage was exposed to either holmium:yttrium-aluminum-garnet (Ho:YAG) or erbium:YAG-laser (Er:YAG) irradiation. Both lasers were operated in a free-running mode and at a pulse-repetition rate of 8 Hz. The effect of laser treatment at several energy levels (Er:YAG at 100 and 150 mJ and Ho:YAG at 500 and 800 mJ) was examined. For each light source and energy level, ten cartilage samples were assessed by conventional histological analysis and by confocal microscopy. Thermal damage was assessed by determining cell viability. RESULTS: The extent of thermal damage demonstrated by confocal microscopy was much greater than that demonstrated by histological analysis. The extent of thermal injury after Ho:YAG-laser irradiation was much greater than that after Er:YAG-laser irradiation, which was associated with almost no damage. In addition, the ablation depth was greater after treatment with the Er:YAG laser than after treatment with the Ho:YAG laser. CONCLUSIONS: In the present study, histological analysis underestimated thermal damage after laser irradiation. In addition, our findings highlighted problems associated with use of high-power settings of Ho:YAG lasers during arthroscopic surgery.

Animals↗

PubMed2004

Cartilage volume quantification via Live Wire segmentation.

RATIONALE AND OBJECTIVES: A reduction in cartilage volume is characteristic of osteoarthritis and hence there exists a need for an accurate and reproducible method to measure in vivo cartilage volume. Quantification of cartilage volume from magnetic resonance (MR) images requires a segmentation technique such as the user-driven "Live Wire" strategy that can reliably delineate object volumes in a time-efficient manner. In the present work, the accuracy and reproducibility of the Live Wire method for the quantification of cartilage volume in MR images is evaluated. MATERIALS AND METHODS: The accuracy of the Live Wire method was assessed by comparing the MR-based volume measurement of a patellar cartilage-shaped phantom versus data calculated via water displacement. The inter- and intra-operator reproducibility of the technique was evaluated from Live Wire segmentation of the patellar cartilage volume from fat-suppressed 3-dimensional spoiled-gradient-echo images of five healthy human volunteers performed by three operators. To provide data for analysis of inter-scan reproducibility, the human scans were repeated five times with the aid of a leg-restraining jig to minimize repositioning error. RESULTS: The volume of the patellar cartilage-shaped phantom measured via Live Wire segmentation of MR images was within 97.8% of its true volume. The average inter- and intra-operator coefficients of variation of three operators were 3.0% and 0.4%, respectively. The average inter-scan coefficient of variation of five repeated scans of each volunteer was 2.7%. CONCLUSION: The data suggest that the Live Wire strategy is an accurate, reproducible, and efficient technique to measure cartilage volume in vivo in a feasible amount of operator time.

Adult↗

PubMed2003

Computer-aided method for quantification of cartilage thickness and volume changes using MRI: validation study using a synthetic model.

The primary objective of this study was to develop a computer-aided method for the quantification of three-dimensional (3-D) cartilage changes over time in knees with osteoarthritis (OA). We introduced a local coordinate system (LCS) for the femoral and tibial cartilage boundaries that provides a standardized representation of cartilage geometry, thickness, and volume. The LCS can be registered in different data sets from the same patient so that results can be directly compared. Cartilage boundaries are segmented from 3-D magnetic resonance (MR) slices with a semi-automated method and transformed into offset-maps, defined by the LCS. Volumes and thickness are computed from these offset-maps. Further anatomical labeling allows focal volumes to be evaluated in predefined subregions. The accuracy of the automated behavior of the method was assessed, without any human intervention, using realistic, synthetic 3-D MR images of a human knee. The error in thickness evaluation is lower than 0.12 mm for the tibia and femur. Cartilage volumes in anatomical subregions show a coefficient of variation ranging from 0.11% to 0.32%. This method improves noninvasive 3-D analysis of cartilage thickness and volume and is well suited for in vivo follow-up clinical studies of OA knees.

Algorithms↗

PubMed1993

Quantification of soft-tissue imbalance in condylar knee arthroplasty.

Soft-tissue balance has been debated in recent publications in connection with the long-term survival of the 'condylar-type' knee prostheses. Present methods of assessment have all assumed that the soft tissues around the knee are inelastic strings. The authors have developed two instruments to quantify soft-tissue imbalance, at the time of the operation, with the assumption that the soft tissues are viscoelastic structures. These two soft-tissue balancing devices were consequently used on 121 patients undergoing condylar knee arthroplasties at the Derbyshire Royal Infirmary and Bretby Hall Orthopaedic Hospital. The first instrument consisted of two flat plates separated by four standard compression springs and provided a qualitative measure of imbalance assuming that the soft tissues were viscoelastic. It was used on 55 patients before being replaced by the quantitative measure of the second instrument. The authors have redefined soft-tissue imbalance, to take into account the viscoelastic nature of the soft tissues, as the resultant trapezoidal geometry of the knee after the bony cuts have been made and when the knee is tensed by equal forces both medially and laterally. The second balancer eliminates the requirement to quantify the individual tensions in the medial and lateral structures by introducing to the system a low-friction, central pivot in the coronal plane. Once the pivot is situated at the centre of the knee, an equilibrium position is achieved where the clockwise and counter-clockwise moments are equal. The tensions exerted by soft tissues can be assumed to be equal and opposite as their moment arms are the same.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗

PubMed2002

Immediate effect of a stabilization splint on masticatory muscle activity in temporomandibular disorder patients.

Surface electromyography (EMG) allows the quantification of the occlusal equilibrium in dysfunctional patients, for instance in those with temporomandibular disorders (TMD). Fourteen patients (ten women, four men) with internal derangement type I were selected among the TMD patients referred to a private practice in Milan. A stabilization splint with posterior contacts was made for each patient. To verify the static neuromuscular equilibrium of occlusion, EMG activity of left and right temporal and masseter muscles was recorded in all patients and the activity (ratio between the activities of the temporal and masseter muscles) index was computed over a maximum voluntary clench test of 3 s. Muscular waveforms were also analysed by computing a percentage overlapping coefficient (POC, an index of the symmetric distribution of the muscular activity determined by the occlusion). The total electrical activity was measured by calculating the area under the entire muscular waveforms. In all patients EMG was performed just before and immediately after the insertion of the splint and data were compared by paired Student's t-tests. Overall, the splint reduced the electrical activity of the analysed muscles (P < 0.005) and made it more equilibrated both between the left and right side (larger symmetry in the masseter muscle POC, P < 0.05) and between the temporal and masseter muscles (activity index, P < 0.01).

Adult↗