Muscle Strains and Ruptures

Introduction

In humans, muscle strain has been characterised into four grades:

Grade I: tearing of a few muscle fibres, pain, spasm, intact fascia, minimal haemorrhage.

Grade II: more severe than Grade I and a haematoma is detectable.

Grade III: tearing of a large amount of muscle with pain and haemorrhage. The fascia is torn and the haemorrhage may be diffuse.

Grade IV: complete rupture of the muscle belly.

Tearing most commonly occurs at the musculotendinous junction.

Muscle strains and rupture can occur in any dog but are more frequent in the racing greyhound.

In pet dogs, muscle strains greater than grade I are rare, and generally other causes of lameness are diagnosed.

In the forelimb, injuries often occur to the: rhomboideus, serratus ventralis, pectoralis, triceps, extensor carpi radialis and flexor carpi ulnaris.

In the hindlimb, muscles commonly injured include the: iliopsoas, tensor fascia lata, sartorius, pectineus, gracilis and Achilles mechanism.

Avulsion of the gracilis muscle is one of the most common and serious racing injuries of the Greyhound.

Diagnosis

This is based primarily on palpation, manipulation and observation.

Acute signs include: pain, lameness, swelling and haematoma formation.

Chronic cases present with: muscle atrophy, scarring of muscle, less painful.

An understanding of the muscle's anatomy and function is essential in making a diagnosis.

The most common area of injury is at the musculotendinous junction, but it can occur anywhere from origin to insertion.

Ultrasound may be useful in diagnosing grade II and III injuries.

Grade IV injuries should be more obvious.

Treatment

Strains are treated with ice and NSAIDs the first 1-2 days, rest for 1-3 weeks and progressive physical therapy.

Grade III and IV injuries may benefit from haematoma removal, surgical debridement and closure if the ends of the muscle can be maintained in apposition.

Excessive tension is avoided, as suture can easily tear through muscle, and tension-reducing patterns are used, such as the horizonal and vertical mattress or the near-far-far-near pattern.

The suture must engage the tendinous tissue in and around the muscle to give it strength.

Suture material commonly used is PDS or poylglycolic acid.

Muscle Strains and Ruptures Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Orthopaedics Q&A 10

References

Pasquini, C. (1999) Tschauner's Guide to Small Animal Clinics Sudz Publishing

Slatter, D. (2002) Textbook of small animal surgery Elsevier Health Sciences