Peroneus Tertius Rupture

What is a Peroneus Tertius Rupture in Horses?

A peroneus tertius rupture is a tendon injury of the equine hind limb that affects the horse’s ability to coordinate movement between the stifle and hock joints. Although the injury can appear dramatic, many horses recover successfully when the condition is diagnosed early and managed with an appropriate rehabilitation programme.

The peroneus tertius (also known as the fibularis tertius) is a strong tendinous structure located on the front and outer aspect of the hind limb. It originates from the extensor fossa of the femur and extends distally over the tibia towards the metatarsal region. The tendon forms an essential part of the reciprocal apparatus of the horse’s hind limb.

The reciprocal apparatus is a unique biomechanical system that mechanically links the stifle and hock joints. Under normal circumstances, both joints flex and extend simultaneously. When the peroneus tertius ruptures, this connection is lost, allowing the hock and stifle to move independently. This loss of synchronisation is one of the hallmark signs of the injury.

What Causes a Peroneus Tertius Rupture in horses?

Most peroneus tertius ruptures occur as a result of trauma or sudden overstretching of the hind limb. Common causes include:

• Slipping on wet or unstable ground
• Falling during exercise or turnout
• Running into fences, gates or other solid objects
• Getting a hind limb caught in wire fencing
• Jumping injuries
• Hyperextension of the hock joint
• Panic-related accidents in stables or trailers

In some cases, the tendon may be partially torn, while in others a complete rupture occurs. Additional damage to surrounding soft tissues may also be present and can influence the prognosis

Symptoms of a Peroneus Tertius Rupture

The clinical signs are often distinctive and can provide a strong indication of the diagnosis.

Common symptoms include:

• Lameness of varying severity
• Delayed protraction of the hind limb
• Abnormal hind limb movement during trot
• Swelling along the course of the tendon
• A visible depression or “dimple” in the muscles
• of the lower thigh or upper crus
• Loss of coordinated movement between hock and stifle
• Reduced flexion of the hock
• Difficulty engaging the hindquarters
• A classic diagnostic sign is that the veterinarian can extend the hock while simultaneously flexing the stifle. In a healthy horse, this movement is mechanically impossible because both joints are linked through the reciprocal apparatus.

Interestingly, many horses can still bear weight on the affected limb despite the injury. This sometimes causes owners to underestimate the severity of the condition.

How Can VetkinTape Support Rehabilitation?

VetkinTape may be incorporated into a comprehensive rehabilitation programme to provide sensory stimulation and support normal movement patterns during exercise. The tape is commonly applied along the course of the injured tendon to encourage awareness of limb position and movement.

Many therapists use kinesiology tape during controlled rehabilitation exercises such as:

• Walking in hand
• Pole work
• Cavaletti training
• Functional strengthening exercises
• Proprioceptive retraining

The application should always be adapted to the stage of healing and the specific needs of the horse.

Step-by-step equine kinesiology taping application

Taping treatment for horses

Step by step instructions of how to apply tape for this particular condition to use during rehab exercises with the horse. If you prefer the application to stay on for a few days in a row, it is recommended to use less tension.

1. Cut one long stripe of tape, according to the horses proportion
2. Start the application over the fossa extensor of the femur (origin of peroneus tertius), applying with no stretch
3. Stretch the active part about 50% and apply the tape towards the third metatarsus
4. End the application with no stretch over the dorsal part of the third metatarsus (just in its proximal part).

Prevent Fibularis tertius rupture

To prevent a peroneus tertius rupture, the horses should not be left alone in an arena they would possibly try to jump out of. Nervous horses should not be left alone in a stall with a low door or an open window due to the same reasons. In jumping training they should not be worked on a slippery ground or over too high fences, to avoid overextension of the hock.

VetkinTape veterinary kinesiology tape

VetkinTape is an elastic & adhesive kinesiology tape developed specifically for veterinary purposes.  It is used by animal physiotherapists and veterinary professionals to relieve pain, improve muscle function, blood circulation & lymphatic flow and support joints.