Influence of lumbar sagittal profile on pelvic orientation and pelvic motion during postural changes in patients with ankylosing spondylitis–related thoracolumbar kyphosis following pedicle subtraction osteotomy

OBJECTIVE The objective of this study was to investigate the impact of the lumbar sagittal profile on pelvic orientation and pelvic motion during postural changes in patients with ankylosing spondylitis (AS) and thoracolumbar kyphosis and to evaluate the potential risk of prosthetic dislocation after total hip arthroplasty (THA) following pedicle subtraction osteotomy (PSO). METHODS Seventy-two patients with AS-related thoracolumbar kyphosis following spinal osteotomy were retrospectively reviewed, and 21 healthy volunteers were recruited as a control group. Pre- and postoperative 2D full-body images in standing and sitting positions were obtained to evaluate the anterior pelvic plane angle (APPA), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), proximal femur angle (PFA), and femoroacetabular flexion during postural changes. Patients with AS were categorized in either a lordotic or kyphotic group based on the lumbar sagittal profile. RESULTS Significant increases in the SS and decreases in the APPA, PT, and LL were observed postoperatively in both the standing and sitting positions (p < 0.001 for all). Significantly higher APPA, PT, LL, and ΔPT, and lower SS, ΔSS, and ΔSS+ΔPFA were observed in the kyphotic group (p < 0.05). After undergoing PSO, ΔPT and ΔSS significantly decreased while femoroacetabular flexion significantly increased in both AS groups (p < 0.05), and no significant difference was present between the two groups (p > 0.05). Bath Ankylosing Spondylitis Radiology Hip Index scores in the kyphotic group were significantly worse than those in the lordotic group pre- and postoperatively (p < 0.05). No significant difference in parameters concerning pelvic motion (ΔAPPA, ΔPT, and ΔSS) was found when PSO was performed in the thoracolumbar or lumbar spine. CONCLUSIONS Lumbar sagittal profiles greatly affect pelvic orientation and pelvic motion in AS. When THA is performed before PSO, AS patients with lumbar kyphosis are at higher risk of anterior prosthetic dislocation, while those with lordotic lumbar sagittal profiles are at higher risk of posterior dislocation. PSO should be performed prior to THA. After PSO, further decreased pelvic motion indicated a potential risk of posterior prosthetic dislocation after sequential THA, whereas theoretically patients with preoperative lumbar kyphosis are at higher risk of THA dislocation. The site where PSO was performed (thoracolumbar or lumbar spine) does not influence the risk of THA dislocation.

Proposal of Wheeled Gait-Training Walker with Dual-Assist Arms and Preliminary Pelvis-Handling Control

To achieve good rehabilitation in a person, the amount of walking by the person must be increased. Herein, a compact wheeled gait-training walker with dual-assist arms for assisting pelvic motion is proposed. The training walker is constructed by modifying a commercial wheeled walker with armrests. Therefore, it can be used easily by patients to perform their daily activities at rehabilitation sites. The hardware system and controller of the proposed assisting arms are designed based on gait-assist motions conducted by a physical therapist. The dual arms can achieve a pelvis-assisting motion with five degrees of freedom. A trajectory-following control with virtual compliance is implemented for the arms. Gait-assisting experiments are conducted, in which the dual arms allow a pelvic-like plate to follow the trajectory of a reference pose while reducing the upper body’s weight resting on the armrests. A 20 N force on the armrests, which represents the upper-limb load, is reduced while the plate follows the trajectory, and the proposed gait-assisting controller is validated.

Pilot Study of Wobble Seat on Trunk Muscles Activity and Kinematics

This paper presents the pilot study of wobble seat on trunk muscles activity and kinematics. For this study the wobble board and wobble board on bearing surface were used to compare muscles activity and body segments kinematics on these different platforms. Two pelvic motions were performed: anterior – posterior and side to side. During this study the electromyography (sEMG) of trunk muscles and motion capture analysis were done. Results showed that sitting on wobble board placed on bearing surface leaded to increment of the activity of deep muscles with smaller pelvic movement in anterior – posterior pelvic motion.

Determining Trendelenburg test validity and reliability using 3-dimensional motion analysis and muscle dynamometry

Background The hip abductor muscle group stabilises the pelvis during gait to prevent excessive pelvic drop. Hip abductor weakness has been linked to musculoskeletal conditions such as chronic low-back pain. As such, it is important that practitioners can correctly diagnose hip abductor weakness in a clinical setting. Although the Trendelenburg test is commonly used by practitioners, the validity of this test to assess hip abductor weakness in the absence of musculoskeletal injury remains questionable. The aim of this study was to determine the validity of the Trendelenburg test, as observed by a practitioner, to assess frontal plane pelvic motion and hip abductor strength in a population without intra-articular hip disorders. Methods This study was performed between June 14th and October 16th 2019. Eighteen participants were recruited for this study. Peak normalised isometric and isokinetic hip abductor torque were measured bilaterally (n = 36) using the Biodex System 4 isokinetic dynamometer. Each participant performed the Trendelenburg test bilaterally (n = 36) while a graduate year chiropractic practitioner assessed for a “positive” or “negative” sign. The test was simultaneously recorded using Vicon 3-Dimensional motion capture to measure frontal plane pelvic motion and elevation. Correlation analyses were performed between the measures of peak hip abductor torque and pelvic motion to determine if any relationship existed. Agreement between the practitioner and 3-Dimensional analysis was calculated using the kappa (κ) statistic. Results Weak, non-significant correlations were found between hip abductor strength and pelvic motion before outlier removal. Significant (p < 0.05) yet weak correlations were found after outlier removal, except for isometric hip abductor strength. Weak agreement was found between the chiropractic practitioner and 3-Dimesnional analysis for the Trendelenburg test assessment (κ = 0.22–0.25). Conclusions This study found no significant relationship between normalised peak isometric and isokinetic hip abductor torque and frontal plane pelvic motion during the Trendelenburg test in a healthy young adult population. There was also poor agreement between the practitioner and pelvic motion assessments. Caution should be used when using this test, in the absence of intra-articular hip pathology, to assesses hip abductor weakness. Before any definitive conclusion can be made, studies with a larger sample size should be performed.

Effects of Modified Pilates Exercises on Pain, Disability, and Lumbopelvic Motor Control in Patients With Chronic Low Back Pain

Purpose: Musculoskeletal disorders, like Low Back Pain (LBP) are associated with impaired lumbopelvic motor control. The current study aimed to investigate the effect of modified Pilates exercises on pain, disability, and lumbopelvic motor control in patients with chronic LBP. Methods: In this randomized controlled single-blind clinical trial, 30 chronic patients with chronic LBP were selected using the convenience sampling method. Then, they were randomly assigned to two groups of control and modified Pilates exercises. The treatment program in the modified Pilates exercises group was based on the Pilates method, and the control group performed general exercises. Lumbar-pelvic motion control index (compression biofeedback unit), muscle tardiness (Endurance test & Sorensen test), pain score (Visual Analogue Scale), and functional disability score (Oswestry Low Back Pain Questionnaire) were measured before and after the intervention. The collected data were analyzed using the Wilcoxon Signed-Rank test and Mann-Whitney U Test (P<0.05). Results: In the modified Pilates exercise group, pain score and disability index suggested significant differences (P=0.001). The lumbar-pelvic control index in the BKFO indicated a significant change (P=0.004). Besides, lumbar muscle endurance also presented a significant change (P=0.001). There was no significant difference between the investigated variables in the intergroup comparison (P>0.05). Conclusion: The modified Pilates exercises effectively increased the level of muscle endurance and the control of lumbar-pelvic motion, and reduced pain and disability.

Pelvic motion the key to understanding spine–hip interaction

Pelvic motion acting as a hinge between the spine and hips is essential to maintain proper balance during bipedalism. Pelvic rotation is recruited as a compensation mechanism when spinal malalignment occurs. This pelvic rotation can affect functional acetabular orientation, and consequently functional cup positioning if a total hip arthroplasty (THA) is needed. Pelvic retroversion, frequently associated with degenerative spinal changes, implies an increase of acetabular version. Patients with flexible lumbar spines (spine users) protect the hip joint. Patients with stiff, degenerated or fused lumbar spines (hip users) demand higher hip mobility, placing the THA at risk. Pelvises in retroversion place the THA at risk for anterior dislocation when standing. In contrast, pelvises in anteversion or with low pelvic incidence (PI) can place THA at risk for posterior dislocation when sitting. Try to set the cup in an anatomic position. However, bear in mind that low PI pelvises may need more acetabular ante-inclination, and high PI pelvises more acetabular retroversion. If surgery is needed, start first by addressing the hip, except in patients with compensation (high pelvic retroversion), who may need spine surgery first to place the pelvis, and consequently the acetabulum, in a proper position. Cite this article: EFORT Open Rev 2020;5:522-533. DOI: 10.1302/2058-5241.5.200032