Over the month of July, Dr Patrice Mich from the Canine Rehabilitation Institute has been joining us live in a series of webinars focused on veterinary orthotics and prosthetics (V-OP). I would love to share some of the most eye-opening insights I gained from this series.
Whether you’re bandaging and splinting or fitting and using custom-made orthoses and prostheses in your practice, an understanding of biomechanics, the forces at work in a brace, and the needs of specific joints or structures being addressed is essential to a good, injury-free outcome for our patients.
V-OP is certainly not a simple and straightforward field, and understanding biomechanics and the application of forces is essential to a successful outcome. Let’s dive into some highlights!
Bandaging and splinting
As we look more closely at V-OP, we really need to start with an understanding of bandaging and splinting, and how we can use a biomechanical approach to improve the outcomes of these treatment options.
In 2011, Meeson et al. showed that in a population of dogs with external coaptations, 63% developed a secondary soft-tissue injury or cast-related wound, with 20% of these being severe or serious. The extra cost to owners could amount to 121% of the cost of the original orthopedic procedure. We must be able to do better than this!
For the sake of clarity, let’s define the different options we have and why we might choose one over another. Bandaging should be used to pad, protect fragile epithelium, debride or maintain a clean environment. A wrap is used to apply compression and mild support in the absence of structural impairment. A splint is used to immobilise, restrain or support a body part, and is usually temporary.
An orthoses or brace is a device designed to control, correct or compensate for a deformity, deforming forces, or forces absent from the body. These can be dynamic, adjustable and easily removable. A prosthesis is used to replace or augment a missing or impaired part of the body, such as replacing part of a limb in the image above.
The biomechanics
There are two primary forces we need to keep in mind at all times – the total body force vector (TBFV) and the total ground reaction force vector (GRFV). The TBFV originates in the body, while the GRFV originates at the point of ground contact. A moment is created when the GRFV passes a distance from a joint, leading to flexion or extension in that joint in response to this force. A moment will be resisted by anatomical structures such as tendons, ligaments and muscles. When there is a disruption in the moment – for example, in the event of an Achilles tendon rupture, decoupling occurs between the TBFV and the GRFV. To really understand these forces and how they are acting, I would recommend watching the series.
When decoupling occurs and we have a moment that is no longer being resisted by the internal structures of the body, we need to use an external coaptation to recouple our force vectors. We can use a three-point system to achieve this.
There are two considerations when using a three-point system. The first is the length of the lever arm on each side of the force being counteracted. The longer the lever arm, the less force is needed to counteract it and the more effective and comfortable the brace will be. Secondly, we need to decrease the moment acting on that joint, or the distance between the joint and the line of the GRFV, by bringing the joint into an extended position.
At the end of Dr Patsy’s first webinar, she shares seven steps to avoiding cast-related, soft-tissue injuries, along with points to consider when when choosing the best form of coaptation or stabilisation for a specific patient.
Consider orthoses
A huge variety of orthoses are available in the human orthotics industry, and owners are looking for similar solutions for their animals. For many cases, orthoses are available for direct purchase by the customer on the internet, whether off the shelf or custom made.
While there are many conditions that can benefit from the use of an orthosis, we need to consider carefully whether this is the best solution for an individual patient. Do they have no other options? Are there comorbidities making surgical intervention impossible? Are there financial constraints for the owner, or is the patient advancing in age? There may be many reasons why an owner and veterinary team opt for or against the use of a V-OP solution.
The key to providing this option to your patients is to work within a team that can provide the best possible care and outcome. A diagnosis, good knowledge and understanding of V-OP and a manufacturer that works with you throughout the process are all essential for an optimum outcome.
Consider prostheses
A prosthesis is used to replace or augment a missing or impaired part of the body. In the past, we have considered that dogs do really well with amputations, and while this is true and they can adapt to having three limbs, the effect on their biomechanics is severe. We have an incredible webinar on evaluating and treating the canine amputee by Marinette Teeling in our members’ portal, which highlights the compensatory patterns we need to address, the structures at increased risk of breakdown, and some of the ways we can support these patients.
In the past, amputations have been performed as far proximally as possible, while today, with the availability of prostheses, amputations are more commonly performed as far distally as possible, thus salvaging as much of the functional limb as can be saved. This allows for the fitting and use of a prosthesis.
This approach gives the patient a far better, more functional outcome than amputation alone, and protects them from developing secondary conditions as a result of significant biomechanical adaptations in movement.
The Achilles mechanism
The Achilles tendon complex is the strongest tendon in the body, and is subject to extreme forces during sporting activities. Injury to this area can occur as a result of trauma, repetitive strain or systemic disease.
When rehabilitating an Achilles injury, we aim to regain weight bearing support, propulsion ability and braking ability through the tendon. The first step in achieving this is to ‘fix’ the tendon through surgical reattachment when required, or by immobilising the tendon through the use of an orthosis. We then want to protect the tendon from re-injury, a process that takes more than 12 months while restoring tendon glide, function and muscle activity, and aiding in the correct fibre alignment of the healing tendon.
The use of functional bracing in this treatment process can greatly aid in improving our outcome, as we can allow immediate weight bearing, correct the function of the claw-paw, and gradually increase the amount of mobility available in the hock.
The addition of a removable paw piece with a heel can significantly improve the walking biomechanics of the patient, improves rehabilitation of the paw, and allows graduation through removal of the paw piece as more range of motion is needed.
Dr Patsy shares some especially valuable evaluation and assessment tools, including objective measures of function/dysfunction. The focus in assessment should be on the degree of stifle hyperextension, tarsal hyperflexion, and clawing of the paw.
The use of a stifle orthosis in cranial cruciate ligament ruptures
In this webinar, Dr Patsy discusses stifle biomechanics and whether the use of an orthosis is appropriate for treating CCLR, whether it is appropriate for an individual patient, and how to assess the products available on the market.
When it comes to managing stifles conservatively, there is a great deal of controversy and disagreement. Many who look at the stifle from a biomechanical perspective agree that conservative management is not a viable option for this joint, and Dr Patsy is certainly in agreement with these experts. From an evidence-based perspective, there is good evidence for the use of surgical procedures, making this the best option for the treatment of cruciate injuries. Conservative approaches, including the use of orthoses, have very little evidence to support their use.
Educating clients on the challenges and management of a stifle orthosis is essential. An orthosis will need to be worn all day, every day for the rest of the patient’s life. They will still develop arthritis, and will need bi-annual fittings and maintenance checks.
There are also multiple considerations when looking at the kind of orthosis used, where the forces are applied, and how the orthosis is designed, as the three-point stabilisation system will not be sufficient for this complex joint with multiple planes of motion.
I would highly recommend listening to the full webinar in our members’ portal if you are interested in learning more about the requirements when considering a stifle brace.
Conclusion
The field of Veterinary Orthotics and Prosthetics is exciting and rewarding, and can greatly impact the lives of our patients for the better. Patient selection is essential, as orthoses and prostheses are not the best option for every patient. In addition, the custom design and manufacture of an orthosis is very important to ensure proper fit and function in our canine patients.
If you have watched our webinar series and are interested in gaining further knowledge on the field of V-OP, it may be worth checking out the course offered by the Canine Rehabilitation Institute.
Resources
Download our Free Research Citation Booklet to keep track of the evidence that is relevant to you in your practice.
Watch the following webinars in our small animal members’ portal:
- Veterinary Splinting, Orthotics and Prosthetics, a four-part series with Dr Partice Mich
- Assistive Devices, with Dr Marti Drum
- Veterinary Orthotics and Prosthetics, with Dr Martin Kaufmann
- Brace and Master Cast with Confidence, with Ben Blecha
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