Biomedical subjects

E Lou

Publications and source records attributed to E Lou.

At least 19 recordsLinked to original sources

PubMed2006

Validity and reliability of active shape models for the estimation of Cobb angles in adolescent idiopathic scoliosis.

Choosing the most suitable treatment for scoliosis relies heavily on accurate and reproducible Cobb angle measurement from successive radiographs. The objective is to reduce variability of Cobb angle measurement by reducing user intervention and bias. Custom software to automate Cobb angle measurement from posteroanterior radiographs was developed using active shape models. Validity and reliability of the automated system against a manual and semi-automated measurement method was conducted by two examiners each performing measurements on 3 occasions from a test set (N=22). A training set (N=47) of radiographs representative of curves seen in a scoliosis clinic was used to train the software to recognize vertebrae from T4 to L4. Images with a maximum Cobb angle between 20 degrees and 50 degrees, excluding surgical cases, were selected for training and test sets. Automated Cobb angles were calculated using best-fit slopes of the detected vertebrae endplates. Intra-class correlation coefficient (ICC) and standard error of measurement (SEM) showed high intra-examiner (ICC > 0.90, SEM 2-3 degrees) and inter-examiner (ICC > 0.82, SEM 2-4 degrees), but poor inter-method reliability (ICC=0.30, SEM 8-9 degrees). The automated method underestimated large curves. The reliability improved (ICC = 0.70, SEM 4-5 degrees) with exclusion of the 4 largest curves (>40 degrees) in the test set. The automated method was reliable for moderate sized curves, but did not properly detect vertebrae in larger curves. Optimization of constraints on scaling, rotation, translation, and iteration may improve reliability with larger curves.

Adolescent↗

PubMed2006

Prediction of brace treatment outcomes by monitoring brace usage.

Brace treatment is the most commonly used non-surgical treatment method for adolescent idiopathic scoliosis (AIS). This study determined whether curve progression can be predicted by how often and how well children with AIS wear their braces. Twenty subjects (3M, 17F) who were diagnosed with AIS and had worn their braces from six months up to 1 year participated into this study. All subjects were prescribed Boston style braces and have now completed their brace treatment. On average, the brace was used 57% of the prescribed time. Peterson's risk of progression (Risser sign, age, apex of curve and imbalance of curve) predicted only 3-8% of the curve progression of brace subjects. Knowing how brace subjects used their braces in terms of brace tightness increases the prediction rate to 12-21%; and wear time further increase it to 25-36%. Adding the multiple of brace tightness and wear time improves curve progression prediction to 41-54%. To be most effective, the brace should be worn as prescribed in both tightness and time manners.

Adolescent↗

PubMed2006

Associations between quality-of-life and internal or external spinal deformity measurements in adolescent with idiopathic scoliosis (AIS).

In theory, quality-of-life measures should correlate with impairments such as spinal deformity. The goal was to determine the ability of the SRS-22 and surface topography measures to predict internal deformity. Data from 227 females with AIS were collected. Correlations and regression were used to predict Cobb angle or category. In subjects treated conservatively, the Cobb angle correlated with pain, self-image, satisfaction and total score. Only self-image correlated with surface topography. In subjects having had surgery, Cobb angle correlated with self-image, mental health, satisfaction and total scores. The cosmetic score was the only external deformity measure to correlate with the SRS-22. Function, self-image and trunk-twist predicted subjects within 3 categories (Cobb <30 degrees , 30-50 degrees , >50 degrees) with 57% accuracy compared to 53% when using self-image only. Accuracy in predicting subjects with curves smaller or larger than 50 degrees was 79% (using self-image, trunk-twist) or 72% (self-image only). Correlations between quality-of-life and deformity measures were low. However, it was possible to predict subjects within clinically meaningful categories of internal deformity using SRS-22 scores.

Adolescent↗

PubMed2006

Improving brace wear with active brace system.

There is considerable controversy regarding the effectiveness of brace treatment for patients with adolescent idiopathic scoliosis (AIS). Researchers believe that to be effective, patients must wear their braces as prescribed including both compliance and tightness. Compliance is how much time the brace is worn relative to the prescribed time. Brace tightness is usually prescribed by orthotists during brace fitting session. Asking the patient or examining the brace for wear are the most common methods to evaluate the brace usage. A low powered microcomputer system was developed to monitor and maintain loads exerted by braces used to treat children with spinal deformities during daily living. This system records brace usage information and helps patients to wear their brace at the prescribed tightness. Laboratory tests have been performed and six patients have used the system for four weeks. The patients reported that the system helped them to wear the brace properly. The time that the patients wore the braces at the prescribed tightness level increased from 48+/-16% during the monitor period (first 2 weeks) to 63+/-18% during the automatic adjustment period (last 2 weeks).

Adolescent↗

PubMed2006

Intra-operative spinal load and displacement monitoring: towards a better understanding of scoliosis correction mechanics.

Surgical correction of scoliosis reduces deformation and improves overall function and esthetics. Understanding and monitoring of mechanics during scoliosis surgery is an invaluable tool to optimize correction without compromising patient safety. Our objective was to use intra-operative monitoring tools to study how spinal load and displacement relates to obtained correction and chosen instrumentation. Instrumented pedicle screws, a "gripper" and active markers were developed. Instrumented pedicle screws provided three-dimensional forces at the screw-vertebra interface while the instrumented "gripper" measured the force and the rotation applied by the surgeon to the rod rotator. Vertebral displacement was monitored with light-emitting diodes and motion capture technology. These instruments were used successfully with 16 scoliosis subjects. Analysis of applied force, displacement, and curve flexibility influence on correction percentage is the long term goal. Raw results for instrumented screws and gripper showed that recorded force decreased with respect to percentage of correction obtained. Measured force increased with respect to the pre-surgical Cobb angle while percentage of correction obtained decreased as pre-surgical Cobb angle increased. Active marker results showed three-dimensional vertebral rotation and translation during correction, with axial rotation and caudal-cranial translation having the greatest magnitudes. Using greater correction forces does not necessarily result in an increased correction; flexibility and Cobb angle also play a role in the mechanics of correction. Further data collection will provide better understanding of the interconnected role between these factors helping complete the description of surgery mechanics.

Biomechanical Phenomena↗

PubMed2005

Smart orthosis for the treatment of adolescent idiopathic scoliosis.

There is considerable controversy regarding the effectiveness of orthotic treatment for patients with adolescent idiopathic scoliosis. Most researchers believe that, to be effective, the orthosis must be worn as prescribed for both compliance and tightness. Compliance is the time the brace is worn relative to the prescribed time. A battery-powered microcomputer system was developed to monitor and maintain the loads exerted by orthoses used to treat children with spinal deformities during daily living. This system not only records how well and for how much time the brace has been used, but also helps patients to ensure that the brace is being worn at the prescribed tightness. Laboratory tests were performed, and five patients used the system for four weeks. The patients reported that the system helped them to wear the orthoses correctly and comfortably. The time that the patients wore the orthoses at the prescribed tightness level increased from 53 +/- 9% during the monitoring period (first 2 weeks) to 68 +/- 14% during the automatic adjustment period (last 2 weeks).

Adolescent↗

PubMed2004

Correlation between quantity and quality of orthosis wear and treatment outcomes in adolescent idiopathic scoliosis.

Orthotic treatment is the most commonly used non-surgical treatment method for adolescent idiopathic scoliosis (AIS). This study determined whether treatment outcome correlates with how often and how well children with AIS wear their orthoses. Eighteen (18) subjects (3M, 15F) who were diagnosed with idiopathic scoliosis and had worn their orthoses from 6 months up to 1 year participated in this study. All subjects were prescribed Boston braces to be worn full time (23 hrs/day). Twelve (12) subjects who completed their brace treatment were included in the data analysis. Three (3) treatment outcomes were classified as improvement, no change and deterioration. The quality of the brace wear was assessed by how often the brace was worn with zero force, below 80%, between 80 to 120%, and above 120% of the load level prescribed in the clinic. The quantity of brace wear was determined by how many hours per day they wore their brace. Subjects who wear their braces tighter and for more hours per day seem to have better outcomes.

Adolescent↗

PubMed2003

Bluetooth wireless database for scoliosis clinics.

A database system with Bluetooth wireless connectivity has been developed so that scoliosis clinics can be run more efficiently and data can be mined for research studies without significant increases in equipment cost. The wireless database system consists of a Bluetooth-enabled laptop or PC and a Bluetooth-enabled handheld personal data assistant (PDA). Each patient has a profile in the database, which has all of his or her clinical history. Immediately prior to the examination, the orthopaedic surgeon selects a patient's profile from the database and uploads that data to the PDA over a Bluetooth wireless connection. The surgeon can view the entire clinical history of the patient while in the examination room and, at the same time, enter in any new measurements and comments from the current examination. After seeing the patient, the surgeon synchronises the newly entered information with the database wirelessly and prints a record for the chart. This combination of the database and the PDA both improves efficiency and accuracy and can save significant time, as there is less duplication of work, and no dictation is required. The equipment required to implement this solution is a Bluetooth-enabled PDA and a Bluetooth wireless transceiver for the PC or laptop.

Computers, Handheld↗

PubMed2003

Clinical and pathological features of the murine AT-84 orthotopic model of oral cancer.

OBJECTIVE: The murine AT-84 orthotopic model of oral cancer was assessed to find how similar it is to human oral cancer. This was done because testing of new treatments for oral cancer requires the use of a realistic animal model. MATERIALS AND METHODS: Tumors were induced at orthotopic (oral) or heterotopic (flank) sites and their features were compared. The therapeutic effects of surgery, 5-fluorouracil and cisplatin were measured on the orthotopic tumors. RESULTS: Tumors had the histological appearance of a sarcomatoid carcinoma, invading locally and causing weight loss and death. The oral tumors metastasized to the lungs frequently. Tumors could be treated with some success by surgery or chemotherapy, but generally recurred. CONCLUSIONS: The similarities to human oral cancer suggest that the model will be very useful in the evaluation of experimental therapies for oral cancer.

Animals↗

PubMed2002

Using three-dimensional difference maps to assess changes in scoliotic deformities.

The three-dimensional nature of scoliosis, coupled with changes due to natural history or treatment, is often difficult to quantify and visualise. A difference map was developed to compare the sequential surface topography of subjects over their treatment period. Three-dimensional surface maps representing patients' trunk surfaces were captured with a laser scanner. Patient surface maps from two clinic visits were matched using a manual best-fit technique that accounted for growth and positioning. The surfaces were subtracted, generating a colour-coded three-dimensional difference map displaying the surface changes. The difference maps were compared with known clinical measures, indicating good agreement (78% specific) with the clinical parameters in detecting change. Full agreement or agreement with the clinical parameters occurred in the surgical, brace and no treatment groups: 76%, 80% and 85%, respectively. A difference index (average of the absolute value of differences on a point-by-point basis) was calculated from the difference map, enabling quantification of change. The difference index, with zero being a perfect match, averaged 5 +/- 1 for repeated measures 7 +/- 2 for subjects deemed to have no change, 9 +/- 2 for subjects with slight change, and 14 +/- 2 for subjects with significant change. The difference map showed the extent and location of changes and is a useful tool for assessing surface topography changes.

Adolescent↗

PubMed2002

Instrumented rod rotator system for spinal surgery.

An electronically instrumented rod rotator has been developed to monitor forces and moments applied by surgeons during the derotation manoeuver to correct spinal curvature. This instrumented rod rotator consisted of an inclinometer and two pairs of strain gauges, with all the support circuitry. The strain gauge and the inclinometer data were sampled with a data-acquisition system, and the results were displayed in real time. The device was calibrated in the laboratory and used on seven subjects. The precision of the load measurement of this device was +/- 5 N in the range of 5-65N. The distance between the middle of the rod rotator handle to the rod position was 0.21 m. The maximum loads applied by the surgeon during seven surgeries were from 22 to 57N, with a torque (force x distance) from 4.6 to 12 Nm.

Adolescent↗

PubMed2002

Effect of herpes simplex virus type-1 on growth of oral cancer in an immunocompetent, orthotopic mouse model.

Herpes simplex virus type-1 has been proposed as an agent for the treatment of oral cancer. Experiments were designed to test its effectiveness in an animal model that had a high level of similarity to the human disease. The mouse oral cancer cell line, AT-84, was implanted at an orthotopic site--the base of the tongue--into syngeneic, immunocompetent C3H mice. As expected, tumors invaded the musculature of the tongue, eroded the mandible, and metastasized to the lungs. To obtain a suitable strain of HSV-1 for therapy we screened 17 fresh clinical isolates and selected one that grew to a high titer in vitro. The mouse tumors were then treated by injection of HSV-1 at a titer of 10(9) plaque-forming units/milliliter. To prolong the anti-tumor effect some mice were also given cyclophosphamide, hydrocortisone, or a second injection of virus. To find the importance of bystander killing of tumor cells, some mice were given virus with ganciclovir. A reduction in tumor volume for a limited period was seen after treatment by HSV-1, and was increased by a second injection of virus or by the administration of cyclophosphamide. Ganciclovir negated the anti-tumor effect. Virus was detectable in the tumors for up to 7 days, and loss of virus coincided with the time at which growth of tumors resumed. The mortality of the mice varied up to around 50%. It appears that (1) a non-attenuated strain of HSV-1 can inhibit the growth of an aggressive malignant oral tumor, but only to a limited extent and (2) inhibition depends on the ability of the virus to replicate in the tumor. It is suggested that mutations in the virus will be necessary to prevent mortality, but must be designed carefully so as not to reduce the virulence of the virus.

Animals↗

PubMed2002

The daily force pattern of spinal orthoses in subjects with adolescent idiopathic scoliosis.

The efficacy of orthotic treatment for children with abnormal spinal curvature has been hampered by the lack of comprehensive information about wear characteristics. A battery-powered microcomputer system was developed to monitor loads exerted by orthoses used to treat children with spinal deformities during daily living. The system not only records how well the orthosis has been used, but also helps to ensure that the orthosis is being worn as prescribed. Data acquisition is controlled by a microcontroller and can be programmed to have sample intervals ranging from 1 second to 1 hour. Low power control circuitry is designed so that the system can be operated by a battery. In a preliminary study, 16 subjects (3M, 13F) used this system from 1 to 16 days (9.3 +/- 5.0) with the prescribed hours between 16 to 23 hours (22.3 +/- 1.3). This study demonstrated the feasibility of the approach, and that this device may increase the understanding of orthotic mechanics, and may help patients to wear their orthoses in a better way.

Adolescent↗

PubMed2002

Evaluation of a laser scanner for surface topography.

A Minolta VIVID 700 portable non-contact 3D laser scanner was evaluated on 15 subjects with idiopathic scoliosis. The 3D map was compared to two structured light pattern (lines and dots) techniques to determine the reliability, ease of use, speed, and quality. The parameters used for the clinical assessment of scoliosis were measured twice for the Minolta and light projection systems. The edges of the image and areas where occlusion typically occur were examined. The absolute distance in calculated depth between adjacent points was examined to determine errors. The Minolta system and the dot pattern produced regular grids of points. The light projection pattern produced an irregular grid, with more resolution along the video line and less resolution between projected lines, resulted in a somewhat jagged appearance of the surface map. The Minolta system was less sensitive to edge effects, occlusion, and sharp transitions of depth. The comparison of clinical parameters showed good results between repetitions but moderate results between techniques.

Adolescent↗

PubMed2002

Brace monitoring system for the treatment of scoliosis.

Determining the efficacy of brace treatment for AIS has been hampered by poor data on the wear pattern of those children prescribed this treatment. Although there is some information on brace compliance, there is very little on how well the brace is secured and the resulting loads imposed on the trunk. The purpose of this study was to determine the daily brace wear pattern of adolescents prescribed Boston braces. The brace monitoring system consists of a force transducer and a microcomputer unit. A force transducer was placed in the lining of the Boston brace. The microcomputer unit was carried while the brace was worn. The force imposed by the brace pad during daily activity was recorded at 1 minute intervals over a period of 3 to 14 days. The samples were stored by the microcomputer. Five subjects (3F;2M; age: 14+/-2 years) who were to wear the brace full time were studied. The subjects adjusted their braces to a prescribed level of tightness as indicated by a light on the microcomputer. Overall compliance, compliance during school days, and forces imposed by the brace were analysed. The force provided by the Boston brace varies considerably during daily activity. Overall brace compliance was lower than expected, with 2 of 5 subjects wearing their brace infrequently. The compliance rate during school time was not different than during the rest of the study period. Peer pressure at school did not appear to affect brace compliance.

Adolescent↗

PubMed2002

Is the Boston brace mechanically effective in AIS?

The application of three-point loading is thought to be the essential basis for effective bracing of adolescent idiopathic scoliosis. Care is taken to ensure that active pressure pad is located to provide maximum support to the apex of the scoliosis while minimizing its lordosising effect. Paradoxically, while cited as an essential factor in the design of braces, there is no consensus as to the importance of such loading to the clinical effectiveness of braces. It may be that braces are effective but that they are effective for reasons unrelated to mechanics. There are few studies that link brace mechanics and change in spinal alignment. Optimal bracing for AIS requires a much better understanding of the role of the mechanical support of braces used to treat AIS. Sixteen subjects, 3 males and 13 females, were participated to this study to determine the correlation between quantity and quality of brace wear and treatment outcomes in AIS. This study showed that the target force levels set for the active pad in braces prescribed for the treatment of AIS vary considerably and that brace applies the desired load 25% of the prescribed time.

Adolescent↗

PubMed2002

Intelligent brace system for the treatment of scoliosis.

Measurement of the biomechanical effectiveness of a brace for the treatment of scoliosis has been hampered by the lack of compressive information about wear characteristics. Orthotists and orthopaedic surgeons believe that the effectiveness of bracing is correlated with the strap tensions. If the strap tensions can be maintained at the optimal level while patients wear their braces, a better treatment outcome may be obtained. However, strap tensions vary significantly during different activities. An intelligent brace system has been developed to control the strap tension so that the optimal prescribed level is maintained at all time. This system consists of an innovative strap tension transducer, a microcomputer unit and a motorized unit. The strap transducer has been developed with an accuracy +/- 1.0N in the range of 0 to 100N. An instrumented Boston brace was built to test the concept. When the strap tension was below 80% of the prescribed level for a 15 minutes interval, the microcomputer unit signaled the motor to tighten the strap. While the strap tension level was above 120% of the prescribed level for a 15 minutes interval, the motor reversed the direction. Laboratory testing results showed that the strap tension could be maintained at the optimal prescribed level.

Artificial Intelligence↗

PubMed2002

Spine-Straight device for the treatment of kyphosis.

Kyphosis is an excessive rounding of the upper spine. Its treatment depends upon the severity, the age of the patient and the levels of the spine that are affected. Early diagnosis is a key to providing optimal treatment. In a skeletally immature patient, an exercise program or bracing is the most commonly used treatment. However, the compliance of bracing for adolescents is poor and exercise training is labor intensive. The purpose of this study is to determine whether a Spine-Straight device can help patients to correct their kyphosis themselves and there by reduce back pain without the biomechanical support of a brace. The Spine-Straight device consists of an accelerometer and a microcomputer unit. The accelerometer is used to measure the kyphotic angle and the microcomputer unit controls a pager vibrator to alert patients when their posture exceeds personalized thresholds. The system was tested in the laboratory before used by subjects. The results were compared to back data obtained from a laser scanner imaging system. The maximum angle deviation between the laser scanner and the Spine-Straight device was 1.5 degrees. Two volunteers tested the systems for 2 days. The accelerometer was placed at the T3 location and the microcomputer unit was carried during daily activities. The angle measurement was recorded at 1 minute intervals during daily activity over a period of 2 days. The preliminary trials demonstrate subjects can improve their posture when feedback signals were provided.

Adult↗