Soft Tissue Injuries
Lameness in dogs is common, which if you’ve been following this blog, you’ve seen many of the most common causes. Sometimes, the cause is more subtle and it is difficult to localize. Often times, the cause of these more elusive lameness conditions is a soft tissue injury. Soft tissue injuries can be muscle or tendon strains, or ligament sprains. It would be hard to cover all of the possible soft tissue injuries here without this week’s blog going on for days, so I will try to sum up some of the more common soft tissue injuries we see for rehabilitation. Tendinopathy is a term used to describe conditions in and around tendons arising from overuse. It could be a tendonitis or tendinosis. Tendonitis is an acute inflammation of the tendon caused by either injury or repetitive strain. Tendinosis is a chronic condition with degeneration of a tendon due to overuse, but there is no inflammation present.
Common soft tissue injuries include (but are not limited to):
Biceps tendinopathy
Supraspinatus tendinopathy
Patellar tendinopathy
Iliopsoas strain
Biceps tendinopathy is a common cause of shoulder pain. These injuries may be due to strains or tears, or may be due to a secondary cause like impingement by other structures, such as the supraspinatus tendon. Performance dogs often experience repeated strain injury of the biceps due to quick turns, overstretching of the muscle, and repetitive contractions/overloading. Degeneration of the tendon may occur with repetitive strain and continuous reinjury of the tendon may lead to shoulder joint instability.
Diagnosis
Dogs often have a shortened stride and a weight bearing lameness which worsens with activity. Performance dogs may have difficulty turning to the affected side and are reluctant to jump. Palpation over the biceps tendon may be painful. Chronic cases may show mineralization of the tendon on x-ray.
Treatment
Medical management and rehabilitation are recommended. Controlled activity, NSAIDS, icing, and physical therapy are primary treatments. If these fail to achieve the desired response, intra-articular injections may be considered. Finally, surgery is recommended if there is an avulsion or tear of the tendon. It is important to note that complete healing of a tendon takes 6-12 months! Six weeks after a surgical repair, the tendon only has 50% of its original strength and one year after repair, 80% of its original strength. The tendon remodels in response to the demands placed on it. Healing without any loading leads to a disorganized and weak structure so it is important that these injuries are rehabilitated in the proper way.
Supraspinatus tendinopathy presents very similarly to biceps tendinopathy since the tendons are located in the same area. For this reason, it is important to really identify which structure is the root cause so treatment can be directed appropriately. Ultrasound and MRI are useful to diagnose.
Anatomy review: The biceps muscle bends the elbow and extends the shoulder. It is also responsible for stabilizing the shoulder during standing and during the weight bearing phase of gait. The supraspinatus muscle extends the shoulder and advances the limb. It is an important stabilizer of the shoulder and is active 65%-80% of the time when the dog is standing. It is important to note that because dogs are quadrupedal (walk on four legs), they have about 60% of their body weight on their front limbs and 40% on their rear limbs. This is due to the weight of their head and neck on the front of the body.
Patellar tendinopathy is a common complication after surgery for cranial cruciate ligament disease. This usually occurs within the first month after surgery and is diagnosed by pain on palpation of the tendon and the tendon is noted to be thickened. For this reason, excessive stress on the patella tendon should be avoided until the tissues adapt to the altered joint mechanics from surgery. Rehabilitation can help reduce the discomfort.
Iliopsoas strain occurs from excessive force acting on the muscle and often occurs at or near the muscle-tendon junction, but can be in the muscle belly itself. These strains often occur during eccentric contraction (contraction when the muscle is elongated). Examples of this are slipping and having the legs splay out, jumping out of a car, or rough play with other dogs. It often results in acute lameness. Iliopsoas strain is not usually an isolated injury, but rather from compensation due to another primary cause, such as cranial cruciate ligament rupture or back issues. They are difficult to cure and often return especially if due to an underlying issue so it’s important to diagnose the cause of the strain.
Anatomy review: the iliopsoas is made up of the iliacus and psoas major muscles which originate on the lower spine and pelvis and come together to insert on the upper femur (thigh bone). These muscles help to move the hind limb forward by flexing the hip. They also rotate the upper leg outward, and bend the lumbar spine.
Diagnosis is usually made by exam and palpation of the area. Exam may reveal lameness, with a shortened stride and decreased hip extension. It may occur on one side or both sides. There is often pain with extension of the hip. Palpation reveals pain, tightness, discomfort, and sometimes even spasm of the muscle.
Treatment initially may include medical management with NSAIDs or muscle relaxants, controlled activity, and icing. Rehab is essential for pain management and strengthening. Core strengthening is vital as well as gradual strengthening of the iliopsoas itself to prevent reoccurrence. If conservative management fails, regenerative medicine, such as stem cells or platelet rich plasma, may be used, or surgery may be indicated. Surgery is performed when irreversible changes, such as fibrosis, have occurred.
References:
Duerr, Felix. (2020). Canine Lameness, WILEY Blackwell
DeCamp, C.E., Johnston, S.A., Dejardin, L.M., Schaefer, S.L. (2016). Brinker, Piermattei, and Flo’s Handbook of Small Animal Orthopedics and Fracture Repair (5th edition), Elsevier
Millis, Darryl L. & Levine, David. (2014). Canine Rehabilitation and Physical Therapy (2nd edition), Elsevier
Zink, Chris & Van Dyke, Janet B. (2018). Canine Sports Medicine and Rehabilitation (2nd edition), WILEY Blackwell
Next Week: Inherited and Growth Conditions in Dogs