Supraspinatus and biceps tendinopathies often go hand in hand in canine patients with shoulder pathologies, and can be challenging to effectively treat and resolve.
Supraspinatus and biceps tendinopathies are pathologies of the tendons of the shoulder joint in canine patients. They commonly occur concurrently in active, large breed dogs as chronic injuries.
Let’s have a look at what the evidence says about the this condition in the canine population.
Before we dive into the research, here is a quick refresher of the anatomy of this region.
The shoulder joint is a simple spherical synovial joint between the glenoid cavity of the scapula and the head of the humerus. The joint capsule extends into the bicipital groove and forms a synovial sheath around the tendon of origin of the biceps muscle. The biceps tendon is kept in place by the transverse humeral ligament. The shoulder joint can move in flexion, extension, abduction and adduction through quite a wide range.
The biceps brachii originates in the supraglenoid tubercle of the scapula, passes through the intertubercular groove, and inserts on the medial and proximal aspect of the radius on the radial tuberosity and the ulna. It acts as an extensor of the shoulder and a flexor of the elbow.
The supraspinatus muscle originates in the supraspinatus fossa of the scapula and inserts on the greater tubercle of the humerus, placing it in a position where it can impinge on the biceps brachii. The supraspinatus muscle is responsible for extension and stabilisation of the shoulder joint.
What does the research say?
There is some evidence on canine biceps and supraspinatus tendinopathies:
- Extracorporeal shockwave therapy and therapeutic exercise for supraspinatus and biceps tendinopathies in 29 dogs
- Ultrasound of the normal canine supraspinatus tendon: Comparison with gross anatomy and histology
- Regenerative medicine for tendinopathies in the canine
- Ultrasonographic evaluation of the canine shoulder
- Supraspinatus and biceps brachii tendinopathy in dogs
- Supraspinatus tendinopathy in 327 dogs: A retrospective study
- Mineralization of the supraspinatus tendon in dogs: a long-term follow-up
- Ultrasonographic evaluation of canine supraspinatus calcifying tendinosis
- Supraspinatus tendinosis associated with biceps brachii tendon displacement in a dog
The research focuses on veterinary interventions, in mostly retrospective studies. We do not yet have any data on the effect of rehabilitation, exercise modification and therapeutic exercise on the outcomes of these pathologies.
These conditions seem to be overrepresented in large breed dogs that lead an active lifestyle.
A supraspinatus injury often presents as an already chronic injury to the tendon at its insertion on the greater tubercle. There will be pain on direct palpation of the tendinous insertion. It often occurs bilaterally and concurrently with an injury of the biceps tendon, or changes in the elbow joint. While the opposite shoulder is often affected by supraspinatus tendinopathy, it may be asymptomatic. Pain may be elicited through manipulation of the shoulder, especially into shoulder extension.
A biceps tendinopathy will be painful when the shoulder is hyperflexed and the elbow hyperextended. On palpation, the biceps tendon may also be nodular, palpably thickened, or have a spongy feeling. Direct pressure over the tendon will elicit a pain response.
Dogs will generally exhibit a chronic intermittent weightbearing forelimb lameness that worsens with exercise in both of these conditions.
The exact cause is unknown, but the literature suggests that chronic overuse injuries are the main suspects. The occurrence of this injury in large breed active or sporting dogs seems to support this.
An initial injury to the supraspinatus tendon can occur as a result of a direct impact over the muscular insertion that fails to heal because of the continuous load bearing nature of the structure. Biceps tendinopathies can be caused by impingement and compression from an enlarged and already pathological supraspinatus tendon.
There may also be an aspect of degeneration of the tendinous insertion owing to ageing. Additional factors may include the occurrence of a joint mice entrapment secondary to osteochondritis desicans, and the occurrence of hypoxia secondary to hypovascularity of the affected tendon.
A diagnosis can be made through a combination of a clinical exam and imaging techniques. Radiography can reveal mineralisation of the supraspinatus or biceps tendon, and active bony changes on the supraglenoid tubercle. Ultrasound can reveal tendon thickening, irregular fibre patterns, effusion of the biceps tendon sheath, and a defect at the insertion site of the biceps tendon. Arthroscopy can help differentiate suprascapular and biceps tendon lesions, and is useful in assessing the biceps tendon. An MRI is considered the gold standard in diagnostics.
Conservative treatment with NSAIDs is indicated only in acute case presentations, as chronic cases will lack the necessary signs of inflammation, rendering NSAIDs less effective. Regenerative medicine with PRP or stem cells can be indicated. For biceps tendinopathies, inter-articular cortisone injections can be successful. Shock wave therapy is showing some promise in the treatment of this condition and is being more regularly utilised. Chronic cases can be highly challenging to manage conservatively, with or without physiotherapy, and can carry a poor prognosis.
If conservative management fails, surgical management is the next step, and is aimed at excising the diseased portion of the supraspinatus tendon longitudinally near its insertion on the greater tubercle, or releasing the proximal biceps tendon from its origin on the supraglenoid tubercle.
Drawbacks of traditional conservative approaches
NSAIDs can play a role in management if administered in the acute phase of the injury, when an active inflammatory process is occurring. As most of these cases are presented in the chronic phase, NSAIDs may hold more risk of side effects than benefit for pain relief.
Intra-articular cortisone injections in cases of biceps tendinopathy also carry some risk, as the articular cartilage can be negatively impacted and osteoarthritis accelerated.
Alternative treatment modalities
Regenerative medicine with PRP and stem cells, as well as shockwave therapy, should be considered. Initial studies on shockwave therapy for these tendinopathies have shown promise, and the therapy should be further investigated and considered as a treatment option for chronic lesions.
Supraspinatus tendinopathies are hard to treat and have a very guarded prognosis. Chronic cases are generally unresponsive to physiotherapy and conservative management.
Biceps tendinopathies have a good long-term prognosis, but a return to full sport can be affected.
Supraspinatus and biceps tendinopathies remain challenging to treat, and while some research has been performed to evaluate the effect of specific veterinary interventions, the effect of veterinary physiotherapeutic interventions have not yet been sufficiently investigated. Many questions remain unanswered and unclarified. When treating these cases as Vetrehabbers, we must consider the requirements and timelines of tendon healing in our patients, and serve to modify and progress loading in an appropriate manner to stimulate optimal healing and recovery of these structures.
Essential facts of physical medicine, rehabilitation and sports medicine in companion animals, Barbara Bockstahler (ed.)
regenerative medicine updates, Matt Brunke