Infraspinatus muscle contracture

Case example

No big stretch for this dog

A 2 year-old, female-spayed German Hunting Terrier was presented for chronic, persistent left thoracic limb lameness and pain on shoulder palpation.

CT findings

The left infraspinatus muscle volume is markedly decreased (image 1). There is no evidence of associated contrast enhancement. An amorphous increase in soft tissue to mineral attenuation is within the central and caudal aspect of this muscle, indicating fibrosis (image 2). A mild amount of smooth periosteal new bone extends along the ventral aspect of the infraspinatus fossa and caudal scapular margin  (image 3). The volume of the remaining thoracic limb musculature is mildly atrophied (image 1).

Conclusions

  • Fibrotic left infraspinatus muscle contracture with secondary disuse muscle atrophy of the thoracic limb.

Learning points

  • Fibrotic contracture of the canine infraspinatus muscle (FCIM) can be imaged via ultrasonography and cross-sectional imaging, such as in this case Computed Tomography (CT). High-field Magnetic Resonance Imaging (MRI) would be the imaging modality of choice, given its superior contrast resolution.
  • Due to superimposition of anatomy and low contrast resolution radiography is not the diagnostic imaging modality of choice.
  • This disease mainly affects hunting dogs, being a rare musculotendinous disorder. Usually, a characteristic circumducted gait develops after an acute onset of non-weightbearing lameness with initial pain, induced by repetitive micro- or direct trauma.

More information

  • »CT findings in a dog with subacute myopathy and later fibrotic contracture of the infraspinatus muscle«
    — Mikkelsen et al., Vet Radiol and Ultrasound. 2021 Mar
  • »Subacute and chronic MRI findings in bilateral canine fibrotic contracture of the infraspinatus muscle«
    — Orellanna-James et al., JSAP 54(8) 2013; 428-431
  • »Fibrotic contracture of the canine infraspinatus muscle: Pathophysiology and prevention by early surgical intervention«
    — Devor et al., Vet and Comp Orhopaedics and Traumatology 2006; 19(2); 117-21

Images courtesy of the Kleintierpraxis Untersiemau, Germany.

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