Shyi-Kuen Wu

Segmental Percentage Contributions of Cervical Spine During Different Motion Ranges of Flexion and Extension

Study Design A blind, repeated-measure design was employed in the study. Objective To quantitatively measure the percentage contribution of segmental angular motion during different motion ranges of cervical flexion-extension for clinical applications and better understanding of cervical biomechanics. Summary of Background Data Restriction of cervical motion is a major symptom in patients suffering from neck injuries or pathologies. Although segmental angular motion alternation is a criterion for the detection of neck related impairments, the percentage contribution throughout cervical movements is not well understood. Methods A total of 384 image sequences during cervical flexion-extension obtained from 48 healthy adult subjects were analyzed with a precise image protocol using dynamic videofluoroscopic techniques. Results The middle cervical spines demonstrated significantly greater angular percentage contributions at C3/4 (29.89%) and C4/5 (37.14%) angles during the initial 1/3 flexion movement; whereas the lower cervical spines revealed statistically greater angular contributions (C5/6: 22.57% to 29.45%; C6/7: 28.80% to 37.42%) from the middle to final 1/3 ranges of flexion movement (P<0.001). With regard to cervical extension motion, the majority of segmental percentage contributions statistically shifted initially from C5/6 level (30.21%) to C4/5 (24.96%) and C5/6 (26.12%) levels, and finally to the C3/4 (27.55%) and C4/5 (29.77%) segments (P<0.001). Conclusions The segmental percentage contributions in this study might imply that the cervical flexion movement initially relied more on the middle cervical segments and later on the lower ones, whereas a motion pattern trend from lower to middle segments was observed during cervical extension.

Effects of the type and direction of support surface perturbation on postural responses

BackgroundPostural control is organized around a task goal. The two most frequently used types of tasks for postural control research are translational (translation along the anterior-posterior axis) and rotational (rotation in sagittal plane) surface perturbations. These types of perturbations rotate the ankle joint, causing different magnitudes and directions of body sway. The purpose of this study was to investigate the effects of the type (translation vs. rotation) and direction (forward/toe up vs. backward/toe down) of the perturbation on postural responses.MethodNineteen healthy subjects were tested with four perturbations, i.e., forward and backward translation and toe up and toe down rotation. The onset latency and magnitude of muscle activations, angular changes, and COM displacements were measured. In addition, the kinematic data were divided into two phases. The initial phase reflected the balance disturbance induced by the platform movement, and the reversal phase reflected the balance reaction.ResultsThe results showed that, in the initial phase, rotational perturbation induced earlier ankle movement and faster and larger vertical COM displacement, while translational and forward/toe up perturbations induced larger head and trunk angular change and faster and larger horizontal COM displacement. In the reversal phase, balance reaction was attained by multi-joint movements. Translational and forward/toe up perturbations that induced larger upper body instability evoked faster muscle activation as well as faster and larger hip or knee joint movements.ConclusionsThese findings provide insights into an appropriate support surface perturbation for the evaluation and training of balance.

Postural responses to yaw rotation of support surface

The purposes of this study were to investigate EMG and kinematic responses to yaw rotation of a support surface. Twenty people participated in four conditions, i.e., two velocities (240°/s, 120°/s) and two amplitudes (30°, 15°). Longer latency and smaller muscle responses were induced for yaw rotation, and distal ankle and knee muscles were activated earlier than trunk and neck muscles. Joint kinematics demonstrated larger angular displacements in axial rotation. Velocity and amplitude did not affect onset latency or magnitude of muscle activation but had significant effects on joint movements and COM displacements. Preliminary information about normative data of healthy subjects was obtained, and questions were generated about optimal velocity and amplitude test protocols that require further investigation.

Treatment of Piriformis Myofascial Pain Syndrome Related to Lumbar Facet Lesion: A Case Report

This case report describes a patient with chronic pain due to piriformis myofascial pain syndrome related to lumbar facet joint lesion. The purpose is to demonstrate the elimination of the underlying etiological lesion by lumbar facet joint injection with steroid suspension for a complete and effective treatment of piriformis myofascial pain syndrome in order to obtain a permanent pain relief. A 46 year-old male patient had chronic pain in the right gluteal region and right leg (with tingling) for many years. Initially, he had been treated as piriformis syndrome with oral medicine, physical therapy and local injection, and had only temporary and incomplete pain relief. Finally, he visited our pain clinic and received physical therapy to the lumbar spine based on the presence of positive facet sign that reproduced his clinical symptoms. After physical therapy, he had pain relief much remarkably than before, but still incompletely. Then he received a lumbar facet joint injection at L5-S1 level. Immediately after the injection, he had pain subsided completely. This effectiveness lasted for longer than one year. It is concluded that, in some cases of piriformis myofascial pain syndrome is related to a lumbar facet joint lesion. Treatment of the lumbar facet joint can suppress the symptoms completely for a significantly long period.