The Assessment of the Tendon of Insertion of the Iliopsoas Muscle in Dogs Using Diagnostic Ultrasound Has Good Intraobserver Consistency but Lacks Interobserver Consistency

The iliopsoas muscle (IPM) is a flexor of the hip joint in dogs that is vulnerable to injury. Intraobserver and interobserver reliability of musculoskeletal ultrasound when evaluating the tendon of insertion of the IPM was studied. The IPM tendons of insertion of a randomly selected cohort were screened by one investigator and recorded. Musculoskeletal ultrasound recordings were separated into two groups of 20 dogs with presumptively normal IPM tendons of insertion and 32 dogs with one or two presumptively abnormal IPM tendons. Recordings were anonymized. The 104 tendons from these 52 dogs were independently reviewed twice by three observers. Abnormalities were detected in 6 of 40 presumptively normal IPM tendons (15%) and 59 of 64 presumptively abnormal IPM tendons (92%). Intraobserver repeatability of measurements of tendon dimensions was good (range, 0.24 to 0.76 mm), intraobserver reliability was good or excellent (range, 0.812 to 0.917), and intraobserver consistency was good (all coefficients of variation <20%). All measurements had poor interobserver consistency (intraclass correlation coefficients <0.500). Measurements of the tendon of insertion of the IPM have acceptable intraobserver repeatability, consistency, and reliability but have poor interobserver consistency, suggesting that efforts should be made to standardize the interpretation methods when using diagnostic ultrasound to evaluate problems affecting the tendon of insertion of the IPM in dogs.