# Chronological Evaluation of Gait Ability and Posture Balance after Adult Spinal Deformity Surgery
## 4 Discussion  
Gait disturbance is one of the most severe symptoms for ASD patients. Spinopelvic parameters are very important and useful indicators to check the spinal balance for ASD patients. [PERSON] et al. reported the loss of lumbar lordosis related to loss of leg strength for walking ability in elderly ASD patients [11, 27]. However, there is a difference between gait posture and standing posture over a short time [28]. The 10-m walk test is a performance measure used to assess walking speed in meters per second over a short distance, which can be employed to determine functional mobility, gait, and vestibular function. To check for real gait disturbance, the 10-m walk test has been proven to be a simple and excellent test [29]. According to this velocity, household ambulator < 0.40 m/s; limited community ambulator 0.40 to <0.80 m/s; community ambulator \(\geq\) 0.80 m/s. For elderly patients, spinal balance is very important to prevent falls during walking [5]. Falls in elderly patients may cause hip fractures that lead to the deterioration of their ambulatory function, increasing their dependence on assistance with activities of daily living [30]. The single-leg stand time is an easy and quick balance assessment measurement. And a prior cohort study reported that a decrease in one-leg standing time was associated with falling in the elderly [31, 32]. On the other hand, TUG is a simple test used to assess a person's mobility and requires both static and dynamic balance. This test is usually performed to predict the patient's ability to go outside alone safely [33]. For this study, we regarded TUG as the main evaluation of dynamic spinal balance. Preoperative data of these three tests indicated that ASD patients had worse results than the normal population, thereby they potentially have a high risk of falls and gait disturbance. [PERSON] et al. reported that, in comparison to healthy individuals, ASD patients had an asymmetrical gait pattern and impaired gait ability [34]. Gait ability correlated significantly with the gravity line, spinopelvic alignment, lower extremity joint ROM, and lean volume [34]. In our data, there was no correlation between spinopelvic alignment and gait ability. This is mainly because our patients were all candidates for surgery, so the spinopelvic alignment was extremely deteriorated, and there was almost no difference among the data. One month after surgery, all data of gait analysis were worse than preoperative data. This deterioration of spinal balance and walking ability may be due to surgical muscle damage, postoperative bed rest, and poor adaptation to new spinal alignment. This suggests that medical staff should take care of the ASD patient not to fall during the postoperative rehabilitation period. Six months after surgery, the static and gait ability of the ASD patients became the same level as preoperative status, and the dynamic balance of the ASD patients became better than preoperative status. From these results, it needs 2 to 6 months to regain preoperative spinal balance and walking ability. Twelve months after surgery, all data except static posture balance became better than the preoperative status. The result of 10 m walking speed became 1.09+/\(-\)0.25 m/s and this result is more than 1.00 m/s, which indicates the normal speed of stable walking [17]. For the elderly people, it has been reported that there is a strong correlation between 10 m walking speed and TUG [34], which is equivalent to our data. Most importantly, TUG will improve faster than 10 m of walking ability after ASD surgery. Single leg standing time was not improved at 12 months after surgery. Usually, a long spinal fusion is necessary for ASD patients, so the spinal segmental motion is lost. This segmental spinal motion is very important to control the gravity center, and as a result, static spinal balance is lost for the patients with long spinal fusion.