Ultrasound Measurements of Patellar Tendon: Differences Depending on Previous Training

Roberto Seijas, Marian Lorente, Jaume Llopis, Marta Rius, José Luis Hernández, Andrea Sallent, Oscar Ares


PURPOSE:to evaluate if the lack of experience in musculoskeletal ultrasonography generates measuring errors based on patellar tendon measurements. Ultrasound is recognized as an outstanding tool in musculoskeletal pathology diagnosis, despite being physician-dependent in knowledge as much as in experience.

METHODS: Six donated knees (ages 58-71 years old) were chosen for the present study. Four observers performed the measurements, which were length, thickness and width of the patellar tendon; an expert in musculoskeletal ultrasonography (gold standard), an obstetric sonographer, an orthopedic surgeon and a third-year medical student. An external participant collected all data and analyzed results.

RESULTS: regarding length, an 8% mean decrease with respect to the gold standard’s mean was observed. With respect to the width, the evaluators showed lower measurements with respect to the gold standard, (less than 5% difference) with no constant systematic error, although a trend of a proportional systematic error was observed (0.59). Third, measurements from observers were an 8% higher than the gold standard’s regarding thickness. The evaluator that most approximated measurements to the gold standard performed was the obstetric sonographer.

CONCLUSION: The present paper represents an approach to learning systems in musculoskeletal ultrasound and counseling courses to focus on ultrasound technique knowledge rather than anatomical domains.


musculoskeletal ultrasound; patellar tendon; training; learning systems; gold standard

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