Chapter 5: Gait Analysis: Kinematic and Kinetic Assessments in Users of Orthoses and Prostheses

 

Introduction

Gait analysis is a critical component in the evaluation and design of orthotic and prosthetic devices. By examining how individuals move, clinicians can assess the effectiveness of interventions and identify areas for improvement. This chapter focuses on the kinematic and kinetic assessments used in gait analysis, exploring their importance in understanding movement patterns, optimizing device performance, and enhancing patient outcomes.

Understanding Gait

Gait refers to the manner of walking, characterized by a series of complex movements involving the coordinated action of the musculoskeletal system. Normal gait is typically described in phases, including:

1. Stance Phase: The period when one foot is in contact with the ground, divided into sub-phases such as initial contact, loading response, mid-stance, terminal stance, and pre-swing.

2. Swing Phase: The period when the foot is off the ground, consisting of initial swing, mid-swing, and terminal swing.

Kinematic Assessment

Kinematics involves the study of motion without considering the forces that cause it. In gait analysis, kinematic assessments provide valuable insights into the spatial and temporal aspects of movement. Key kinematic parameters include:

1. Joint Angles: Measurement of angles at key joints (hip, knee, ankle) during various phases of gait. Changes in joint angles can indicate compensation strategies or inefficiencies in gait.

2. Stride Length and Width: Stride length refers to the distance covered in one gait cycle, while stride width indicates the lateral distance between feet. These metrics help evaluate stability and symmetry in gait.

3. Cadence: The number of steps taken per minute, which can reflect overall mobility and endurance. Changes in cadence can indicate fatigue or the need for adaptive strategies.

4. Velocity: The speed of walking is an essential indicator of functional mobility. Reduced velocity can signify underlying issues with strength, balance, or coordination.

5. Center of Mass (COM) Movement: Analyzing how the center of mass moves during gait helps assess balance and stability. Ideally, the COM should move smoothly without excessive lateral or vertical displacement.

Kinetic Assessment

Kinetics involves the study of forces acting on the body during movement. Kinetic assessments in gait analysis focus on understanding the forces that influence walking patterns. Key kinetic parameters include:

1. Ground Reaction Forces (GRF): These forces are generated by the ground in response to the weight of the body during each step. GRF data provide insight into weight distribution and loading patterns, crucial for evaluating the effectiveness of orthotic and prosthetic devices.

2. Joint Moments: These are the rotational forces acting at the joints during movement. Joint moment analysis helps identify which muscles are being activated and how forces are distributed across the joints, allowing for targeted interventions.

3. Power Generation and Absorption: Power analysis evaluates the energy produced or absorbed at joints during gait. This information is critical for understanding how well an orthotic or prosthetic device assists or resists movement.

4. Energy Expenditure: Measuring the metabolic cost of walking can provide insight into the efficiency of gait. Higher energy expenditure may indicate an inefficient gait pattern or inadequate device performance.

Methods of Gait Analysis

1. Motion Capture Systems
   Motion capture technology utilizes cameras and reflective markers placed on the body to track movement in three-dimensional space. This system provides precise kinematic data and allows for the visualization of gait patterns. The data collected can be analyzed to assess joint angles, velocities, and trajectories during various phases of gait.

2. Force Platforms
   Force platforms measure ground reaction forces as individuals walk across them. This equipment provides kinetic data, allowing clinicians to analyze the distribution of forces and assess load-bearing patterns. Force platform data are essential for evaluating how devices affect gait dynamics.

3. Wearable Sensors
   Advances in technology have led to the development of wearable sensors that can measure kinematic and kinetic parameters in real-time. These sensors can be integrated into orthotic and prosthetic devices, providing continuous feedback on movement and performance during daily activities.

4. Video Analysis
   High-speed video recording can be used to analyze gait visually. This method allows for the observation of movement patterns, identification of compensatory strategies, and evaluation of device performance. While less precise than motion capture, video analysis can be a useful tool in clinical settings.

Clinical Implications

1. Device Evaluation and Optimization
   Gait analysis is essential for assessing the effectiveness of orthotic and prosthetic devices. By identifying deviations from normal gait patterns, clinicians can make informed decisions about adjustments or modifications needed to enhance device performance.

2. Personalized Rehabilitation Programs
   Understanding individual gait mechanics allows for the development of tailored rehabilitation programs. Clinicians can design specific exercises and interventions aimed at improving strength, balance, and coordination, ultimately enhancing overall mobility.

3. Monitoring Progress
   Regular gait analysis can track changes in a patient’s mobility over time, providing valuable data on recovery and adaptation to new devices. This information is critical for making ongoing adjustments to treatment plans and ensuring optimal outcomes.

4. Research and Development
   Gait analysis data contribute to the ongoing research and development of new orthotic and prosthetic technologies. By understanding the biomechanics of movement, researchers can innovate devices that better meet the needs of users.

Conclusion

Gait analysis through kinematic and kinetic assessments is a powerful tool in the evaluation and optimization of orthotic and prosthetic devices. By understanding the mechanics of movement, clinicians can enhance the design and functionality of these devices, ultimately improving patient outcomes. As technology continues to advance, the integration of gait analysis in clinical practice will play an increasingly vital role in personalized rehabilitation and device development.