Objective: The objective was to describe clinical and ultrasonographic characteristics of canine Achilles tendon injuries.
Background: Even though there have been publications describing characteristics of the normal and injured Achilles tendon by diagnostic ultrasound, there has been no previous in-depth ultrasonic evaluation and characterisation of Achilles tendon strains.
Evidentiary value: This is a retrospective case series report of 43 dogs that underwent musculoskeletal diagnostic ultrasound evaluation of their strained Achilles tendons, with and without surgical repair.
Methods: Data was collected from medical records of patients from August 2009 to May 2016. Inclusion criteria for dogs included a diagnosis of Achilles tendon injury based on the presence of fibre pattern modification within one or more components of the Achilles mechanism on initial diagnostic ultrasound.
Results: It was found on the diagnostic ultrasound that Achilles tendon injuries were strictly unilateral in 51.2% (n=22/43) of cases and bilateral on presentation in 48.8% (n=21/43) of cases. 18.2% of the unilateral case progressively became bilateral over time (n=4/22). The injury was partial in 90.7% (n=39/43) of the cases and all three components of the Achilles mechanism were completely disrupted in only 9.3% of the cases (n=4/43). The partial injuries incorporated changes within the fibre patterns of all 3 components of the Achilles in 53.8% (n=21/39) of the cases and alteration of both the gastrocnemius tendon (GT) and common tendon (CT) in 41.0% (n=16/39) of the cases. Grade III strains were predominant (44.3%), followed by grade I (28.6%) and grade II (27.1%). Damage occurred most commonly at the tendino-osseous insertion (77%), with injury occurring less frequently diffusely along the body of the tendon (12.5%) or at the musculotendinous junction (10.5%).
Conclusion: Diagnostic musculoskeletal ultrasound was used to identify lesions of Achilles tendon consistent with different grade of strain, as well as identifying the specific region of injury. Diagnostic ultrasound findings were correlated to the surgical findings and previous literature.
Application: Diagnostic musculoskeletal ultrasound provides a non-invasive diagnostic modality for patients suspected of having Achilles tendon strain. Further investigation is needed to establish treatment protocols based on ultrasonographic 3-tier grading scheme for Achilles tendon strain injury.
Abbreviations: Common tendon (CT), computed tomography scan (CT scan), gastrocnemius tendon (GT), magnetic resonance imaging (MRI), myotendinous junction (MTJ), superficial digital flexor tendon (SDFT).