fibrotic myopathy

Fibrotic Myopathy

Gracilis Contracture, Semitendinosis Myopathy

Fibrotic Myopathy is thought to be an uncommon acquired, disorder which probably occurs to some degree after any muscle contusion that heals primarily by scar tissue. The whole muscle or part of the muscle is replaced with fibrous connective tissue within the semitendinosus and, occasionally, the quadriceps muscles of the hindleg. When most or all of the traumatised muscle is replaced by fibrous scar tissue that contracts to an inelastic band, it is termed fibrotic myopathy or muscle contracture.

Fibrotic
Characterized by or affected with fibrosis (the formation of fine scar-like structures that cause tissues to harden and reduces the flow of fluids through these tissues. )

Myopathy
Muscle Disease

Contracture
Prolonged shortening of the muscle or other soft tissue around a joint, preventing movement of the joint.

Male German Shepherds with an age range from 8 months to 9 years are most commonly affected. Other affected breeds include Doberman Pinscher, Rottweiler, St. Bernard, Boxer, and Old English Sheepdog. The cause for the disorder is unknown and could be associated with repeated microtrauma, vascular compromise, primary neuropathy and it can even be immune mediated. Active dogs seem to be susceptible to this disorder, and recent studies in dogs suggest that fibrotic myopathy may be related to muscle injury from excessive activity, including jumping and sprinting that can lead to muscle strain, with a suggested sequence of inflammation, edema, localized hemorrhage, and eventually fibrosis. Most patients suffer some form of trauma weeks to months before the contracture is present. The clinical signs include lameness, pain, weakness, decreased range of motion, a firmness noted throughout the entire muscle, and usually a characteristic gait.


1. Levator Nasolabalis muscle 2. Jaw/nose muscle 3. Masseter muscle 4. Parotido Auricularis 5. Outside masseter 6. Yoke muscle 7. Temporal muscle 8. Chest/tongue/leg muscle 9. Supraspinatus 10. Brachialis	11. Brachiocephalicus muscle 12. Pectoral muscle 13. Trapezius muscle 14. Supraspinatus muscle 15. Shoulder - neck muscles 16. Deltoid muscle 17. Triceps muscle 18. Extensor Carpus 19. Common Digital extensor 20. Lateral Digital extensor	21. Extensor Carpi Ulnaris 22. Flexor Carpi Ulnaris 23. Extensor carpi radialis 24. Lumbo Dorsal Fascia 25. Pectoral muscle 26. Aponeurosis muscle 27. Obliqus Abdominus Externus 28. Gluteus medius muscle 29. Tensor Fasia muscle 30. Sartorious muscle	31. Gluteus Maximus 32. Biceps Femoris muscle 33. Semitendinous muscle 34. Anterior tibial muscle 35. Long Digital Extensor 36. Tibialis 37. Flexor digitorum pedis 38. Flexor Hallicus Longus http://www.camnuschgermanshepherds.com/anatomy.htm

Muscle contractures causing varying degrees of lameness commonly occur from skeletal muscle fibrosis, the result of injury such as that caused by circulatory insufficiency, infection, autoimmune reaction, or trauma. Quadriceps contracture, whether congenital or acquired, is treated by sectioning the cordlike fibrotic muscle group by "Z" plasty, resulting in lengthening it enough to allow the knee to assume a normal standing angle. Adhesion of the muscle group to a large femoral callus (muscle tie down) may occur and require additional surgical correction. Infraspinatus contracture results in a typical foreleg deformity and change in gait. Surgical repair by tenotomy is usually followed by rapid return to normal. Gracilis contracture, though common in racing greyhounds, is not commonly reported in pet dogs. Surgical excision of the entire affected muscle mass is curative. http://www3.interscience.wiley.com/journal/119857472/abstract?CRETRY=1&SRETRY=0

Fibrotic myopathy of the semitendinosus muscle is associated with a palpable thickened fibrous band that may extend from the tuber ischii to the tibia within the belly of the semitendinosus muscle. Tight fibrous cords are also palpable in affected gracilis muscles extending from the midline of the pelvis to the caudomedial aspect of the stifle. In dogs with gracilis and/or semitendinosus muscle involvement, the hind-limb gait is characterized by a shortened stride with a rapid, elastic medial rotation of the paw, external rotation of the hock, and internal rotation of the stifle during the mid-to-late swing phase of the stride. Kinematic analysis indicate that the range of motion of the stifle is reduced. The gait anomaly results from restricted abduction of the coxofemoral joint and reduced extension of the stifle and hock. Note that the lameness is best appreciated at the trot. Bilateral involvement (of the gracilis or semitendinosus muscle) is commonly encountered, with reports varying from 39% to 61% of affected dogs, while both muscles may be involved ipsilaterally or contralaterally. Histologically, the band consists of an abundance of dense collagenous connective tissue, with a distinct interface between connective tissue and muscle bundles. Morphological studies in our laboratory or in others have not identified primary muscle or peripheral nerve disease, although variable myofiber degeneration around the periphery of the fibrotic band has been seen occasionally, sometimes associated with mild mononuclear cell inflammation and focal hemorrhage. The replacement of muscle fibers with dense collagenous connective tissue results in a mechanical lameness resulting from failure to fully extend the limb. Neurological examination is usually normal; however, pressure applied to the affected muscle, abduction of the coxofemoral joints of affected limbs, and extension of stifle/talocrural joints in affected limbs may elicit pain. Serum CK levels may be normal or moderately elevated in some animals. Absence of myoelectrical activity in the band during EMG evaluation is consistent with total replacement of muscle fibers by dense connective tissue; however, spontaneous EMG activity in the vicinity of the band suggests recent muscle damage. In occasional dogs, fibrillation potentials and rare myotonic discharges have been recorded. Imaging techniques have been used to identify the intramuscular fibrous cords in people. Soft-tissue swellings associated with the myotendinous areas of affected muscles may be detected on radiographs, and two-dimensional ultrasonography in one dog revealed increased size and reduced homogeneity of the gracilis muscle, with an enlarged tendon of insertion compared to the normal muscle.
http://www.ivis.org/special_books/Braund/braund20a/ivis.pdf

Fibrotic myopathy is a chronic, progressive, idiopathic, degenerative disorder affecting the semitendinosus, gracilis, quadriceps, infraspinatus, and supraspinatus muscles, primarily in dogs. The cause is unknown. Affected muscles are characterized by contracture and fibrosis. Normal tissues are replaced by dense collagenous connective tissue. Clinical signs include a nonpainful, mechanical lameness. Neurologic function is normal. Surgical release of affected tissues via tenotomy, myotenotomy, Z-plasty, or complete resection produces inconsistent results. Prognosis is guarded due to recurrence.
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/91404.htm

Gracilis Contracture in Dogs	Fibrotic Myopathy scrolldown a little way to 5	Fibrotic Myopathy in a German Shepherd Dog scroll down to video 3	Physical Therapy
Infraspinatus Contracture	Sartorius Muscle Contracture in a GSD	Is Fibrotic (Gracilis) Myopathy due to Muscle Strain in Physically Active Dogs?	Eva is back to work after being treated for fibrotic myopathy