Narrow Results

Objective: To study the therapeutic mechanism of an innovative instrumentation — Plate-Rod System for Scoliosis (PRSS) and its effectiveness for the surgical management of early onset scoliosis (EOS) and adolescent scoliosis (AIS). Method: A new device — PRSS was developed in our department. Between June 2000 and July 2008, 23 patients with progressive EOS, and from October 1998 to August 2003, a total of 66 AIS patients, who underwent one-stage PRSS procedure without bony fusion and had been followed up for more than two years, were evaluated prospectively. The mean age at the time of surgery was 7.98 years in the EOS group, and was 12.15 years in the AIS group. Experimental studies including X-ray analysis, photo-elastic test and type X collagen were used to test the therapeutic mechanism. Results: The subjects were followed up for more than 2 years. The mean scoliosis improved from 80.7° to 30.5° after surgery with a corrective rate of 62.2%. The length of the growth of the instrumented spine was on average 13.3 mm in EOS group. In AIS group, the mean precentage of correction was 68.86%. There were no severe complications in our studies. When PRSS was in place, compressive stress was found to exert on the convex side, while tensile stress on the concave side of the curvature, which was reflected by the changes in the color band in the photo-elastic test and the changes in the width of the disc spaces, and more type X collagen was expressed on the convex side than the concave side. This suggests that compressive stress leads to increase in earlier cartilage degeneration of end plate on the convex side, which is correlated with the decreased growth of the end plate of this side, resulting in maximum spinal realignment. Conclusion: The PRSS which dispenses with spinal fusion and allows extension along with the children's growth, is able to provide and maintain desirable correction of scoliosis in the later growing years due to its modulating efficiency in normalizing the spinal growth. This new device is an effective instrumentation for correcting scoliosis, especially for EOS.

Purpose:Pedicle screw insertion in a deformed and rotated pedicle in scoliosis is technically demanding. A multislice spiral intraoperative computed tomography (iCT)-guided navigation system can assist pedicle screw insertion. However, no studies have been performed to evaluate the pedicle diameter and accuracy of pedicle screw placement in patients with adolescent idiopathic scoliosis (AIS) using one scan iCT-guided navigation.

Methods:This was a retrospective cohort study. iCT was performed before screw insertion and after screw insertion. The pedicle diameters in all planned surgical levels were measured. A pedicle with a maximal diameter of less than 4 mm was considered narrow. A screw with a breach distance of $\le$2 mm was considered accurate.

Results:Twenty-nine consecutive patients with AIS received surgery with 415 pedicle screws inserted in 580 planned screw insertion pedicles. Twenty-five patients had been found to have narrow pedicles (86.2%). Overall, the screw accuracy rate was 98.6% (409/415). Thirty-eight screws were inserted in narrow pedicles and the screw accuracy was 84.2% (32/38). There were no major complications after screw insertion.

Conclusion:One scan iCT-guided navigation provides a high degree of safety and screw accuracy of 98.6% for pedicle screw placement in AIS.

Background: Adolescent Idiopathic Scoliosis (AIS) leads to change between body segments, right-left trunk symmetry and produce pathological gait pattern. The influence of trunk bracing on symmetry of ground reaction force components and loading rate on idiopathic scoliosis has not been well documented. Therefore, the aim of this study was to examine the effect of trunk bracing on symmetry of forces in adolescent with idiopathic scoliosis. Method: A total of 10 patients with AIS and 10 healthy subjects with comparable age, height and weight were recruited in this study. The force applied on the right and left sides in both groups of subjects were recorded by use of a Kistler force plate while walking. The peak of the vertical force (the first and second peaks) and the force applied on the leg in anteroposterior direction (progression and breaking forces) and mediolateral force were collected in this study. Results: The results of this study showed that there was a significant difference between the asymmetry index of anteroposterior force of normal and scoliotic patients $(p=0.05)$. Moreover, trunk bracing decreased asymmetry index of loading rate of scoliotic patients significantly $(p=0.042)$. There was no significant difference between the other examined kinetic variables. Conclusion: There are some degrees of asymmetry between the forces applied on the leg in scoliotic subjects. Orthosis decreased the forces applied on the leg in patients with scoliosis. Clinicians are to be aware of these findings as orthotic devices may be of value to patients with idiopathic scoliosis.

A novel dynamic brace for the treatment of idiopathic scoliosis based on parallel-actuated robotic system is proposed in this paper. The new brace can apply corrective forces on patients’ spine actively to correct the abnormal spine. However, the gravity of the dynamic system results in some adverse impacts, such as reducing comfort degree of patients, accuracy loss of rehabilitation force control, big error in direction and value of force. To overcome this problem, a new active force control strategy, proportional-derivative (PD) control with desired-gravity-compensation (DGC), is proposed to improve the effectiveness of scoliosis rehabilitation. Considering the electrically driven system and the environment contacting with the brace, the dynamic model of the active brace system is derived using Kane method. Based on the above mentioned, the force controller with DGC is designed for the brace system to compensate the impact of system gravity. The brace experiment system is built and various experiment tests are performed to verify the proposed control strategy. Experiment results demonstrate that the proposed control strategy, PD control with DGC, can distinctly reduce the influence of the brace system gravity and has more efficient control effectiveness compared with the classical PID controller.

Background: Although there are a few studies on kinetic and kinematic parameters of scoliotic subjects, it is still controversial whether gait performance of scoliotic subjects differs from that of normal subjects or not. Moreover, there is lack of information regarding joint contact force of scoliotic on convex and concave sides. Therefore, this study examined these issues.

Method: Two groups of children (healthy and children with scoliosis, each group consisting of 5 subjects) participated in this study. The force applied on leg and motions of body parts were evaluated using a Kistler force plate and motion analysis system, respectively. Joint contact forces, muscles length were evaluated in both groups and on both sides (in scoliotic subjects) with OpenSim software. The difference in the parameters between healthy children and scoliotic subjects, and also concave and convex sides, was determined using the independent $t$ test. $P$ value was set at $\le 0.05$.

Results: The results of this study showed that there was no difference between the forces applied on the leg, range of motions of the joints (hip, knee, ankle, pelvic and trunk), muscles length and joint contact force, neither between normal and children with scoliosis, nor between concave and convex sides $(p>0.05)$.

Conclusion: The findings revealed that scoliosis deformity with curve less than $40^{\circ }$ does not have any significant effect on joint contact force, kinetic and kinematic parameters.

While the presence of dynamic neuromuscular stabilization (DNS) has been provided as an important component of the integrated spinal stabilization and associated abdominal stabilization prior to dynamic movement, no previous study has investigated the spinal mechanical effects scoliosis and pain control in youth baseball player with scoliosis. This study compared the effects of gymball exercise, with and without DNS core stability exercise, on spine kinematics and pain control in youth baseball player with scoliosis. A total of 28 participants with scoliosis were randomized into gymball exercise, with and without DNS core stability exercise. Clinical outcomes included the Cobb’s angle and visual analog scale (VAS). Two-way repeated analysis of variance (ANOVA) was conducted at p < 0.05. Two-way repeated ANOVA showed that gymball with DNS showed superior effects, compared to gymball without DNS, on Cobb’s angle (P < 0.001), but not on VAS (P < 0.837). Our results provide novel, promising clinical evidence that DNS improved scoliosis kinematics as well as pain control in youth baseball player with scoliosis.

In the adolescent idiopathic scoliosis (AIS) treatment, a brace is prescribed to the patients who have 20 to 45° curves on their spines to prevent the disorder's advancement. For the analysis of Milwaukee brace effects during time, finite element models (FEMs) of the spine (the thoracolumbar region) and the ribcage (contained 10 pairs of the ribs and the sternum) were prepared for two patients. For modeling the spine part, a new element was used in which a disc (as viscoelastic 3D beam) and a vertebra (as rigid link) were modeled as an element and the ribs and the sternum modeled by 3D elastic beams. The gravity, Milwaukee brace constraints and the forces of the brace's different regions were considered as the FEM boundary conditions. By running the patients' FEMs, the spine deformities of each patient were predicted for 24 h. For AIS patients, the brace should not only correct the deformity of the spine by inserting the forces, but also support the spine from the bending moments being caused by the gravity forces in different spine regions. Moreover, in studying scoliosis pathomechanisms, the stresses in different levels of the vertebra are important. Therefore, the bending moments and compressive stresses, caused by the gravity forces, were calculated in each level of the vertebra and the brace forces effects on them were analyzed. According to the patients' FEM responses, for the female patient: lumbar scoliosis was increased, thoracic scoliosis was decreased and kyphosis and lordosis were increased, and for the male patient: lumbar scoliosis was increased, kyphosis was increased and lordosis was decreased. In standing position, the brace forces reduced the bending moment and the compressive stress in vertebral levels of thoracolumbar region for the female patient and increased them for the male patient.

Adolescent idiopathic scoliosis (AIS) can impair postural stability and balance functions. Boston brace systems with varying external corrective force strategies are used as one of the common conservative treatments in AIS. Although multiple studies have found that various orthotic therapies enhance curve advancement, the effects of spinal bracing on postural equilibrium and stability remain unknown. The primary objective of this study was to examine the effect of the immediate use of custom-made Boston-type thoraco-lumbo-sacral orthosis (TLSO) on balance and postural stability in AIS. Postural balance using the center of pressure (CoP) measures was measured by the HUMAC^Ⓡ Balance & Tilt System (CSMi, Stoughton, MA). The line laser tool (Bosch, GLL 3 X P, Stuttgart, Germany) was used for measuring the decompensation distance for postural evaluation. The balance parameters such as stability score (%), path length (cm), average velocity (cm/s), and compensation–decompensation for posture were evaluated and compared between brace-on and brace-off conditions. Improvement of standing posture indicates spinal symmetry and cosmesis whereas enhancement of static balance was statistically nonsignificant ($p$ > 0.05). Although the mean stability score, path length and average velocity of CoP in braced condition (91.4 ± 4.57, 115.62 ± 22.34 cm and 1.05 ± 0.12 cm/s) was found to be improved than unbraced condition (90.5 ± 5.09, 121.46 ± 35.52 cm and 1.11 ± 0.24 cm/s), the results were nonsignificant ($p$ = 0.078, 0.425 and 0.263). The scoliotic compensation was improved in the braced condition (0.64 ± 0.60 cm) compared to brace-off condition (1.74 ± 0.61 cm) showing improved posture ($p$ = 0.00013). Wearing the custom-made Boston-type TLSO showed positive effects on static posture and mean balance parameters. In future studies, the long-term effectiveness of this brace should be examined in patients with different spinal curve patterns and degrees of scoliosis.