Brace correction based upon mechanical action requires appropriate interface pressure between the body and the brace.

A smart orthotic was developed to record how much time (quantity) a brace was used, how well (quality) it was used and maintain the interface pressure to the prescribed level. Six subjects were recruited and they all used Boston style braces. Each subject used the system for two weeks without the force maintenance system activated to serve as the control period, and the remaining two weeks with the force maintenance system activated. During the automatic feedback mode, the pressure maintenance system was activated only during the daytime (8:00–22:00hrs) to avoid disturbing the patients during sleep. The subject could either return the system to us after one month or continue to use the system until the next clinic.

The time that the pressure level was in the target level range during the study period was increased from 53 +/− 9% to 68 +/− 14% with the feedback activated. The average brace wear time for the study period was 72 +/− 15% (12.6hr/day) of the prescribed time (17.5 +/− 3.8 hours). The curve severity of all subjects on the following clinical visit was the same (within measurement error) as the first visit (32 +/− 5 vs 31 +/− 5 degrees). Compliance was not affected when wearing the monitor.

The smart orthotic was able to improve the efficiency of a conventional brace by maintaining the prescribed interface pressure automatically. This proposed work helps brace candidates wear their braces more effectively and gets the most benefit from the brace treatment. As a result, all participated subjects maintained their Cobb angle within ± two degrees during the study period.

To determine the pattern of brace wear compliance over time in both day and night time wear by using objective force measurements within the brace.

Twenty subjects who were diagnosed of AIS, age between nine and fifteen years, and new to brace treatment were recruited in this study. To use the data for analysis, only subjects who used the brace for five hours continuously either in daytime or nighttime were considered. For daytime wear, the selected five hour intervals had to begin with an initial spike in force after a period of non-activity as recorded by the transducer, which would indicate that they had just put on the brace. At night, the measurements began at one am and ended at six am.

Among the twenty subjects, only nine subjects’ data were used for daytime and eleven subjects’ data were used in nighttime. The average wear period was 11.4 ± 4.3 days for the day group, 11.6 ± 3.9 days for the night group. There was a statistically significant decrease in force within the first five hours of consecutive brace wear during daytime hours. The decrease was from 1.4 ± 0.6 (140% of prescribed force) in the first hour to 1.0 ± 0.6 in the fifth hour, a difference of 0.4, which is a 29% drop from the initial force. Most of the drop in force happened between hour one and hour two, as the difference in those two hours is 0.2 ± 0.1 (p = 0.001); between hours two and five the difference did not reach statistical significance. The observed difference between hours one and five for the night group was 0.2 ± 0.2, p = 0.06, which did not reach significance as well. Daytime forces in a Boston Brace tend to decrease over a period of time, but the nighttime forces seem to be maintained at the same level. These results show that daily adjustment of the brace tightness may be required to maintain the tightness level and the efficiency of brace treatment.

Vertebral growth remains a mystery, especially with regards to the contribution of different growth plates and the mechanisms of growth after closure of these plates. As an example of vertebral growth in general, the growth of the vertebral canal was assessed in a rat model using fluorochromes. Although 80–90% of vertebral canal growth was due to growth plates, the remaining canal growth occurred via periosteal absorption and deposition. This is contrary to the traditional idea that periosteal mechanisms do not change the shape or dimensions of bone and suggests that the vertebrae exhibit a different model of growth than typical bones.

Vertebral growth remains largely a mystery. The contributions of different growth plates and the mechanisms of growth after closure of these plates requires further exploration. As an example of vertebral growth, vertebral canal growth was assessed in a living rat model using fluorochromes.

Vertebral canal growth and presumably vertebral growth in general occurred by different mechanisms at different phases of development. Growth plates accounted for the majority of growth although periosteal mechanisms also resulted in changes in the size and shape of the vertebrae. This is contrary to the traditional concept of periosteal growth and suggests that vertebrae may exhibit a different model of growth than typical bones.

The growth of the vertebrae in a particular dimension and during a particular phase of development is dependent on different mechanisms of growth, which may play a role in interpreting vertebral growth anomalies.

The interspinous junction closed by the end of the first week, whereas the neurocentral junction closed between weeks three and four. By four weeks, the vertebral canal had achieved 80–90% of its growth in area and diameter. After growth plate closure, the canal continued to grow by periosteal mechanisms and was displaced posteriorly.

Thirty-six Sprague-Dawley rats (age one week-seven weeks) were injected with tetracycline and alizarin using a dosing interval of four days. Thoracic vertebrae were sectioned using a cryostat and examined under a fluorescence microscope. In addition to noting fluoro-chrome deposition, the dimensions of the growth plates and canal were noted.

Funding: Edmonton Orthopaedic Research Association and University of Alberta Department of Radiology and Diagnostic Imaging

This study was designed to examine the components of the MR image of the neurocentral junction (NCJ) and to explore the discrepancy between the age of closure of the NCJ as determined by anatomic and imaging studies. MR images of one hundred and fourteen porcine NCJs were correlated with anatomic and histologic sections. Whereas gross anatomic visualization did not reveal the NCJ site, MRI was sensitive for cartilage detection and accurately determined the age of NCJ closure although it overestimated the extent of closure. Based on this study, MRI characterization of the NCJ appears reliable and the NCJ cartilage does not close until adolescence.

This study examined the composition of the MR image of the neurocentral junction (NCJ) and the discrepancy between the age of closure of the NCJ as determined by anatomic and imaging studies.

MRI was sensitive for cartilage detection and accurately determined the age of NCJ closure (i.e. absence of cartilage on histologic examination).

Disparate NCJ development has been implicated as a potential cause of adolescent idiopathic scoliosis. Whereas autopsy studies have refuted this theory by suggesting that the NCJ closes before adolescence, MRI studies have resurrected this idea by suggesting later closure. MRI-histologic correlation suggests that the NCJ cartilage remains present until adolescence and therefore further exploration of the disparate growth hypothesis is required.

Gross anatomic visualization did not reveal the NCJ site, even after removal of the periosteum. In contrast, the presence or absence of an NCJ image correlated with the presence or absence of cartilage although MRI overestimated the extent of this cartilage.

Vertebrae were grossly examined for any evidence of the NCJ site. Sagittal and transverse MR images of one hundred and fourteen porcine NCJs in various stages of development (thirty-eight open, sixty-four closing, twelve closed) were correlated with anatomic and histologic sections acquired at the same position.

Funding: Edmonton Orthopaedic Research Association and University of Alberta Department of Radiology and Diagnostic Imaging

Introduction: No appropriate animal model for studying adolescent idiopathic scoliosis (AIS) exists and this hampers research. In recent years, we have been examining a model in which scoliosis consistently develops in young chickens following pinealectomy and which has been shown to have many characteristics similar to those seen in AIS. Not all of the pinealectomised chickens develop scoliosis following the pinealectomy and so we have the opportunity to examine differences between the two groups. The obvious candidate for study of the mechanism underlying this phenomenon is melatonin which is the principal product of the pineal gland. In this study we have measured the serum melatonin levels of pinealectomised chickens that have developed scoliosis and compared these with similar measurements taken from chickens that have developed scoliosis.

Methods and results: Newly-hatched chickens were obtained from a local hatchery and kept in a single pen with standard heating and lighting. A 12:12 light dark cycle was introduced immediately and the two-thirds of the chickens were pinealectomised three days later. The remainder acted as controls. At weekly intervals following surgery, the chickens were radiographed in a supine position while anaesthetised and the presence of scoliosis was determined from the radiographs. Three weeks after surgery the chickens were euthanised and blood samples were collected and analysed using radioimmunological techniques to determine levels of serum melatonin. The samples were collected in the presence of red light in the middle of the dark cycle when melatonin levels have been shown to be at their highest.

Approximately 55% of the pinealectomised chickens developed scoliosis within the three weeks following surgery whereas none of the control chickens developed scoliosis. The results showed that the serum melatonin levels of pinealectomised chickens were significantly lower than the normal controls and were in fact all close to zero. However, there was no significant difference in serum melatonin levels between those chickens that developed scoliosis and those that did not.

Conclusion: The results of this study have shown that pinealectomy significantly reduces serum melatonin levels close to zero in all chickens. The results also show that there is no significant difference in serum melatonin levels between those pinealectomised chickens that develop scoliosis and those that do not. Unless there is a subtle threshold level that is unable to be detected using our methodology or that melatonin levels in the days immediately after surgery are of critical importance, these results suggest that other causes for this phenomenon need to be examined. An understanding of the underlying cause would be of great importance and might represent a significant breakthrough in the study of AIS.

Introduction: Braces are the most generally accepted form of non surgical treatment for adolescent idiopathic scoliosis (AIS). Despite decades of usage controversy still exists regarding the efficacy of this treatment. We believe this controversy continues in part because there are few studies describing the mechanical effect of bracing and linking mechanically effective bracing to changes in the natural history of AIS. If braces are effective, is it because they apply significant mechanical support to a collapsing spine or are they effective for other reasons? A first step towards answering this question is to document the mechanical action of braces during activities of daily living. This would enable researchers to examine the effect of mechanical support on progression of the scoliosis. The objective of this study was to determine the temporal pattern of forces exerted by the pressure pad in Boston braces prescribed for the treatment of AIS.

Methods and results: A force transducer and a programmable data logger were designed to measure loads exerted by the pressure pad over extended periods of time. The loads were recorded at one minute intervals. Braces were adjusted to a prescribed load level and the patients were asked to set the brace tightness to match this target any time the brace was donned. Brace wear data were stratified into: not worn, worn at less than 80% of target, 80–120% of target and greater than 120% of target. Bracing was considered mechanically effective if the load was at least 80% of the prescribed level. Patients were aware of the study and consented to participate.

Thirteen patients were followed from 1 to 16 days, average was 9±5 days. Nine patients were asked to wear their braces 23 hours per day, two for 20 and two for 16 hours per day. Braces were not worn 34±27% of the time logged. When they were worn, patients adjusted the tightness of the brace such that it was < 80% of the target 29±20% of the time, within 20% of target 19±19% and over 120% of target 18±13% of the time. Patients wore their braces at or above the target levels 33% of the time logged or 8 hours in a typical day. Subjects had no difficulties using the data logger and none complained that it interfered with brace wear. Reviewing individual histories suggested that subjects did not alter their brace wear pattern because of the data logger.

Conclusion: The mechanical effectiveness of the brace varies considerably over the normal course of wear but seldom does it provide the support intended. While patients wear their braces for about 16 hours per day, it is mechanically effective for 8 hours only.

Introduction: Although there are several known causes of scoliosis, most are of unknown cause and develop during adolescence, making adolescent idiopathic scoliosis (AIS) the most common form. It has long been hypothesised that unilateral closure of the neurocentral junction accompanied by continued growth on the opposite side could lead to vertebral rotation and subsequent lateral curvature. However, autopsy studies of neurocentral junction closure in children has revealed that these joints close at approximately six years of age consequently excluding this hypothesis as a cause of AIS. In contrast, a recent MRI study has suggested that in some children at least, the NCJ does not close until much later in development around the time of puberty thereby resurrecting this hypothesis as a potential cause of AIS. This study was designed to investigate closure time and pattern of closure of the NCJ in normal patients to determine whether further examination of this hypothesis might be warranted.

Methods and results: The morphology of the NCJs in 20 patients between the ages of 3 and 15 were observed in MR images taken for purposes other than spinal anomaly. The structure of individual NCJs were observed and reconstructed in 3-dimensions. The age at which NCJs became closed was determined and pattern of closure of a typical NCJ was created using the reconstructed images. The pattern of closure of the NCJs along the vertebral column was also determined and any differences between right and left sides at the same level was also noted.

The results showed that there was a sequence of closure along the vertebral column for the NCJs with those in the cervical and lumbar regions being the first to close and those at the approximate level of T8 being the last to close. While the NCJs in the cervical and lumbar regions close at 5–6 years of age, those in the thoracic region, that are the last to close, do so at approximately 12 years of age. No significant difference between the stage of closure of the left and right sides was seen at any level.

Conclusion: The results of this study have shown that the closure of the NCJs in those vertebrae that form at approximately the most common level for the apical vertebra associated with AIS (midthoracic) does not occur until the time of puberty. This contrasts sharply with previously held views on the age of closure. Although no significant difference in closure between left and right sides was seen among these particular patients it does not exclude unilateral closure as a cause of AIS at least in some patients. These results suggest that examination of this hypothesis should be resurrected and that further study is well warranted. MR examination of young patients with small, initial curves could be well worthwhile.

Introduction: Trunk asymmetry has been acknowledged as an important aspect of scoliosis that is difficult to treat. Recent innovations in the surgical management of idiopathic scoliosis have attempted to improve trunk symmetry as well as spine curvature. But there have been few reports in the literature describing the effectiveness of these procedures on trunk alignment. The objective of this study was to determine the long-term changes in spine and trunk alignment after surgery for scoliosis.

Methods and Results: 38 subjects were identified as candidates for this study. Fifteen were lost to follow-up. Of the remaining 23 subjects, 20 (15 female, 5 male; age at surgery 16±5 years) agreed to participate and had posterior-anterior radiographs and surface topography prior to derotational surgery, within six months of surgery, at two years post-operatively and 5-10 years after surgery. Three subjects had anterior instrumentation and 17 had posterior instrumentation. Cobb angles, surface trunk rotations, and cosmetic scores were measured at each visit. A questionnaire assessed back appearance and pain at the 5–10 year follow-up and the results compared to a group who had recently undergone surgery. A paired two tailed Student’s t-test with p=0.01 was used to compare the deformity between visits.

The Cobb angle and cosmetic score improved after surgery; the initial Cobb angle improved to 35±11° (42%). Trunk rotation change was insignificant (p=0.25).

Between the two and seven year reviews, the Cobb angle had significantly increased while the cosmetic score (p=0.07) and surface trunk rotation (p=0.10) were unchanged. The mean back appearance and pain scores were 4.3 for both compared to 4.2 and 4.0 for the control group where 1 is worst and 6 is best.

Imperfect surgical correction of spinal curvature leads to continued changes to spine alignment as well as to cosmesis and trunk alignment, although the increases were not all statistically significant. Responses to the patient questionnaire suggest that these changes are not clinically significant.

Conclusion: Surgery significantly improves trunk symmetry but not trunk rotation. There is mild deterioration of the deformities associated with scoliosis after surgery but these changes do not appear to be clinically significant.