Objective gait analysis in equine lameness exams: MoCap vs. IMU vs. Sleip

For equine veterinarians, a precise lameness exam is crucial for accurate diagnosis and treatment planning. Traditionally, these exams relied heavily on subjective visual observations. However, technological advancements have introduced objective gait analysis systems that provide valuable data for a more comprehensive evaluation. This blog post will compare three leading options: 3D Optical Motion Capture (MoCap) systems, Inertial Measurement Unit (IMU) sensors, and Sleip’s computer vision system.

Where did it start? MoCap and biomechanical research

The journey towards objective gait analysis began with MoCap systems. Pioneered by companies like Qualisys, these systems utilise multiple high-speed cameras strategically placed around an enclosed arena. Reflective markers are attached to specific points on the horse's body. The cameras track the markers' movement in 3D space, generating detailed kinematic data about joint angles, limb movement, and overall symmetry during gait. MoCap offers the highest level of accuracy and is considered the gold standard for gait analysis research. Many of the pioneering biomechanical studies were performed with MoCap. 

Addressing limitations: The rise of IMU Sensors

MoCap systems, while powerful, come with some limitations. The dependence on a calibrated volume may pose restrictions in certain clinical settings. Additionally, the high cost, complex setup, and need for specialised personnel can effectively hinder many veterinary practices. This paved the way for IMU sensors.

These small, wireless devices are attached directly to the horse's body. IMUs contain accelerometers, gyroscopes, and magnetometers that measure acceleration, orientation, and magnetic fields. This data measures upper-body movement (head, withers, pelvis), and some systems estimate joint angles and limb movement. IMU sensors offer a more portable and cost-effective solution than MoCap. 

Making gait analysis accessible: The Sleip App

The Sleip app takes objective gait analysis further by utilising a readily available device - the smartphone. By recording a high-quality video of the horse in motion, Sleip employs computer vision algorithms to track the movement of specific body key points and further analyse gait parameters. This eliminates the need for specialised equipment for horse attachments and setups.

Here's how Sleip compares to MoCap and IMU systems:

Pros of Sleip:

• High-quality video: Provides vets with the opportunity to visually verify and share data, fostering better communication and education, particularly in referral cases.
• Accessibility: ease of use and lower cost: Requires only a smartphone, making it readily accessible, portable, and cost-effective. No additional hardware to manage.
• Frequent updates: Automatic updates ensure access to the latest algorithms and functionalities without requiring any effort from the user.
• Cloud storage: Data is securely stored in the cloud, eliminating concerns about data loss on local devices.
• Telemedicine and monitoring over time: Vets can invite horse owners to record through the Sleip app, with the video and data sent to the vet’s account, making it easier to follow up on treatment and provide remote consultations. Regular monitoring also supports prevention and early detection.

Cons of Sleip:

• Internet dependence: Upload speed and internet connectivity can impact usability and the time it takes to get analysis results back.
• Recording limitations: Because Sleip uses a single camera and analysis can be performed anywhere, environmental factors like lighting conditions, dust or rain can impact the quality of the recording. Similarly, if the horse is too far away from the camera, analysis cannot be performed. The app handles these issues automatically and only includes quality strides in the analysis. 

Conclusion: Choosing the right tool for your needs

When it comes to equine gait analysis, the ideal system depends on your specific clinical requirements.

MoCap remains the gold standard for research and clinical applications due to its unparalleled accuracy. However, its high cost, limited portability, and cumbersome setup make it less practical for routine use in most veterinary practices. IMU sensors are more affordable and offer portability. They are a good option for field use, but just as with the MoCap markers, careful placement of sensors is crucial, and some systems require calibration for reliable data. 

Accessibility is a limitation of both these systems, as the hardware can only be used by one vet at a time. By contrast, Sleip allows multiple users, meaning vets at a clinic using Sleip can work with gait analysis simultaneously. They can also share and access data remotely it making it easier to consult with colleagues. 

The Sleip app stands out for user-friendliness and accessibility. Using the smartphone camera as an input tool makes it easy for veterinarians seeking to integrate objective data into their lameness exams. 

Ultimately, the best system is the one that seamlessly integrates into your workflow and provides the information necessary to deliver the best possible care to your equine patients. 

Looking Ahead: The field of equine gait analysis is constantly evolving.  Future iterations of the Sleip application and similar technologies will likely incorporate new parameters, such as withers movement and even 3D mapping, to provide an even more comprehensive picture.