What are Meniscus and Meniscal Ligament Injuries?
Meniscal injuries are the most common cause of lameness seen in the stifle joint, which can be mild to chronically severe. Horses that routinely jump, often while performing, are at a high risk of stifle joint damage. Athletic horses, such as jumpers, race horses, dressage horses, and cutting horses can experience a significant amount of stifle injuries.
The stifle joint is a complicated hinge joint where the femur meets the tibia in the upper hind leg of a horse. It is the largest joint in the horse’s body, and is comparable to a knee in people. It actually consists of three joints, two of which are divided into compartments. Within these spaces, the medial and lateral meniscal ligaments are found. If these ligaments become torn or injured, lameness is often the result.
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Symptoms of Meniscus and Meniscal Ligament Injuries in Horses
Symptoms of a meniscal ligament injury include:
- Decrease in performance
- Behavior or training issue
- Changes in weight bearing or stance
- Reluctance to work
Injuries or tears in the meniscal ligaments are often classified in one of three grades. This grading system can be used to determine the severity of your horse’s injury, and help to form a treatment plan.
- Grade I – This indicates a tear of the cranial ligament that connects to the meniscus, but separation of tissues is minimal
- Grade II - This signifies a complete tear of the cranial pole of the cranial and meniscus ligaments, and can be seen in an exploratory arthroscopy
- Grade III - This refers to a severe tear in the cranial and meniscus ligaments which continues beyond what can be seen
Causes of Meniscus and Meniscal Ligament Injuries in Horses
Causes of a meniscal injury include:
- Injuries or trauma to the meniscal ligaments
- Repetitive jumping, often as part of performing
- Cartilage defect
- Meniscal and cruciate ligament tears
- Defect in the meniscal ligament
- Degenerative joint disease
- Osteochondral fragmentation
- Osteochondritis dissecans
- Bone cysts
- Patellar and collateral desmitis
Diagnosis of Meniscus and Meniscal Ligament Injuries in Horses
When lameness is suspected to be caused by a stifle joint issue, intrasynovial anesthesia is used to confirm the lameness. Your veterinarian will want to see your horse trot or canter. Once lameness is confirmed, then the task of the veterinarian is focused on discovering which part of the joint is injured. After a complete exam, and a medical history is discussed, a number of imaging techniques can be used to narrow down the problem. X-rays, MRIs, and nuclear scintigraphy, or a bone scan, can be used. However, ultrasonography is a more common method to either correctly diagnose a meniscal injury, or to justify further diagnostic techniques, such as exploratory arthroscopy.
Exploratory arthroscopy can be used both as a diagnostic tool and as a treatment. This is a surgery that examines the medial and lateral menisci, as well as the other ligaments and joints in the stifle joint. Through this exploration, the severity and extent of the injury can clearly be seen, and can such a procedure is also recommended after a treatment has failed to further assess the damage.
Treatment of Meniscus and Meniscal Ligament Injuries in Horses
Treatment can involve arthroscopic debridement and removal of any loose tissue, leaving only healthy tissue behind, and can be performed during the exploratory arthroscopy to diagnose the problem. Other treatments can include anti-inflammatories, intra-articular anesthesia to improve lameness, and stall rest with hand walking, followed by a slow return to work. Blood and serum can be drained from the joint with a needle if needed.
Extracorporeal high-energy shockwave therapy can stimulate new bone growth and remove calcified tissue. Stem cell therapy can be helpful, using platelet-rich plasma and bone marrow aspirate concentrate.
Your veterinarian will advise you on how long to rest your horse, as well as an exercise plan to get your horse moving again. An ultrasound is used before exercise is resumed to assess your horse’s progress, and can assist you and your veterinarian in the next steps.
Recovery of Meniscus and Meniscal Ligament Injuries in Horses
It may take many months for your horse’s damaged meniscal ligament to completely heal. Until that time, rest and a gradual return to exercise and work will be planned by you and your veterinarian. You may have medications to administer to help reduce swelling or reduce lameness, and will be scheduled for an ultrasound to check on your horse’s progress during that time.
The rate of recovery and a return to athletic activity depends on the severity of the ligament damage. While half of the cases seen return to athletic activity, others with more severe tears may not fully recover. Complications with other concurrent conditions can make the rate of recovery even lower.