New research sheds light on the kinematic characteristics of tenodesis grasp in individuals with C6 quadriplegia, a type of spinal cord injury affecting hand functionality. The study, published in the journal Spinal Cord, highlights the specific wrist movements and increased movement time required to achieve the tenodesis grasp. These findings have important implications for prehension rehabilitation in quadriplegic patients.
Tenodesis grasp is a compensatory technique that allows individuals with C6 quadriplegia to perform passive prehension movements. It involves the extension of the wrist and can result in two different types of grips: a whole hand grip and a lateral grip. The study investigated the kinematic parameters of tenodesis grasp in four participants with C6 quadriplegia and four healthy control participants.
The results revealed two key kinematic parameters involved in tenodesis grasp movements: wrist flexion during reaching and wrist extension during the grasping phase. Additionally, the study found that participants with quadriplegia exhibited increased movement time, reflecting the adjustment required to achieve the optimal wrist position for the tenodesis grasp. These findings suggest a sequential planning of reaching and grasping movements in individuals with C6 quadriplegia.
The study also compared the kinematic characteristics of whole hand and lateral grips in tenodesis grasp. Both types of grips showed similar kinematic patterns, emphasizing the consistent nature of the compensatory movements in quadriplegic individuals. Understanding these kinematic characteristics is crucial for effective prehension rehabilitation strategies tailored to the unique needs of quadriplegic patients.
The kinematics of normal prehensile movements in healthy individuals were also discussed in the study for comparison purposes. Healthy individuals exhibit a distinct reaching phase involving the shoulder, elbow, and wrist, coupled with a grasping phase requiring finger closure and thumb opposition. In contrast, participants with C6 quadriplegia displayed significant kinematic differences in both the reaching and grasping phases.
During the reaching phase, individuals with C6 quadriplegia exhibited longer movement times and smaller velocity peaks compared to healthy control participants. Compensatory movements involving proximal upper limb joints, such as the scapula and trunk, were also observed. Muscle activation differences were evident in the reaching phase of quadriplegic participants, with isolated activity in agonist muscles but no accompanying antagonist muscle activation.
While reaching phase differences were common in individuals with quadriplegia, kinematic differences during the grasping phase were less frequently reported. However, the study found that tenodesis grasp in participants with C6 quadriplegia involved greater wrist extension, increased wrist height, additional velocity peaks, and forearm supination. These findings suggest the utilization of gravity to secure the grasp.
The study contributes to the understanding of the kinematic characteristics of tenodesis grasp in individuals with C6 quadriplegia. By providing insights into the sequential planning of reaching and grasping movements, as well as the specific wrist movements involved, the research may aid in the development of more effective prehension rehabilitation techniques for quadriplegic patients. Further studies are warranted to expand on these findings and optimize the rehabilitation approaches for improving hand functionality in individuals with cervical spinal cord injuries.
