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Purpose Brace treatment has served as a vital non-surgical procedure for immature adolescent idiopathic scoliosis (AIS) patients with a mild or moderate curve. For the patients who fail in bracing and resort to surgery, it is unclear whether prior full-time brace treatment significantly influences outcomes. This study aims to investigate whether prior brace treatment has a negative impact upon the flexibility and correctability of the main curve in patients with AIS. Methods The participants were collected from female AIS patients who underwent posterior correction surgery with pedicle screw instrumentation from August 2006 to December 2010, with or without prior brace treatment. Patients included in Group A had prior brace treatment over a 1-year period, and underwent surgery within 6 months after cessation of bracing; those in Group B received no prior treatment and were randomly selected from our database. Curve flexibility pre-surgery and curve correctability post-surgery were computed and compared between both groups and subgroups according to the curve location.Results Each group consisted of 35 patients. Age, curve magnitude and location were comparable between the two groups. Before surgery, patients in Group A had a slightly lower curve flexibility than those in Group B (52 vs. 60 %, P = 0.036). After surgery, satisfactory correction results were observed in both groups, but the average post-operative main curve magnitude of patients in Group B was 4°l ess than that of Group A (10°vs. 14°, P = 0.010). The curve correctability in Group B was significantly higher than that in Group A (80 vs. 74 %, P = 0.002). No matter what curve pattern the patient had, having a prior history of brace treatment resulted in a trend of lower flexibility and correctability of their scoliosis. Conclusions Good surgical correction can be achieved in AIS patients who have been unsuccessful with prior brace treatment. However, a history of prior brace treatment leads to a trend of lowering the curve flexibility, and in turn, negatively impacts upon the curve correctability.

There is a positive correlation between the severity and risk of thorax injury and the collision velocity and angle of car-thorax crashes. At the same velocity, it is of greater damage risk when the soft tissue of thorax under a front impact; and there is also a greater risk of ribs fracture under a side impact of the thorax. This result is of vital significance for diagnosis and protection of thorax collision injuries.

In this paper, we design a robust model predictive control (MPC) controller for vehicle subjected to bounded model uncertainties, norm-bounded external disturbances and bounded time-varying delay. A Lyapunov-Razumikhin function (LRF) is adopted to ensure that the vehicle system state enters in a robust positively invariant (RPI) set under the control law. A quadratic cost function is selected as the stage cost function, which yields the upper bound of the infinite horizon cost function. A Lyapunov-Krasovskii function (LKF) candidate related to time-varying delay is designed to obtain the upper bound of the infinite horizon cost function and minimize it at each step by using matrix inequalities technology. Then the robust MPC state feedback control law is obtained at each step. Simulation results show that the proposed vehicle dynamic controller can steer vehicle states into a very small region near the reference tracking signal even in the presence of external disturbances, model uncertainties and time-varying delay. The source code can be downloaded on https://github.com/wenjunliu999.

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