To ascertain whether therapeutic ultrasound (TUS) can be used to assess the progression of conservative management in navicular stress injuries.
This is a prospective, clinical case series. Level of evidence IV.
All participants were examined and followed up in a private Sports Injury Clinic.
Ten elite track and field athletes with severe dorsal midfoot pain over the navicular bone participated in this study.
All patients underwent both TUS and magnetic resonance imaging (MRI) evaluation. The painful threshold of TUS on initial evaluation was a mean of 0.707 ± 149 W/cm2, and MRI detected a navicular stress injury in all patients. The athletes received conservative treatment and underwent sequential TUS evaluations at 4, 8, 12 and 16 weeks.
Main Outcome Measures:
Therapeutic ultrasound pain threshold values were recorded, and the patients were additionally asked to grade local tenderness on a Visual Analogue Scale. Time to return to play was also recorded.
The level of pain produced by the application of TUS on a navicular stress fracture seemed to correlate well with Visual Analogue Scale scores and the grade of fracture demonstrated on MRI. The initial low TUS painful mean value increased to a normal mean value of 1.97 ± 0.067 W/cm2 by 16 weeks. When clinical and TUS findings had returned to normal, the patients were allowed to return to sports activities, with no recurrences experienced during the study period.
The production of pain associated with the application of TUS on a navicular stress fracture is a safe and reproducible method of monitoring the resolution of these fractures. We have used it successfully in making return-to-play decisions for elite level track and field athletes.