Background The anatomy of the proximal tibiofibular (TF) joint is directly related to its ability to withstand stress applied in either a longitudinal or axial fashion. It is traditionally evaluated by CT scan, however, in certain conditions, it could be evaluated by ultrasound (US) conveniently; so far US has not been using to evaluate the TF joint. US is an innocuous, accessible and cheap image technique, that has demonstrated its utility for evaluating joints in several pathologic conditions, and might have an important role in the early diagnosis of inflammatory, degenerative or even tumoral lesions at the level of the TF joint; there are no studies that have evaluated the morpho- structural pattern of the TF joint.

Objectives To describe the morphostructural pattern of the tibiofibular joint in healthy subjects.

Methods Subjects older than 18 yrs old, with no history of past/present lesion of the knee, without any joint or neurovascular disease were included. A short questionnaire related to physical activity applied, and clinical evaluation to discard instability performed. US of both knees in extension done, using an Esaote ® MyLab 70 ultrasound equipment with a 7.5 - 12 MHz linear transducer. Descriptive statistics done

Results Thirty-six patients (27 women, 75%) included, mean age 41.2±8.9 years, mean weight 71±12.46 kg, mean height 1.61±0.09 ms and BMI 71.07±12.40. 69% of the subjects practice mild exercise activities. By US mean distance between tibia and fibula were 3.2±1.17 cm; the mean thickness of the ligaments (superior and inferior) was 3.2±0.99 cm and 3.2±0.89 respectively, and in the superior e inferior fibular ligaments were 3.2±0.99 cm and 3.2±0.89 cm respectively. Ligaments were hyperechoic in 61.1%, a well-defined border was seen only in 48.6%. Inside of joints a hypoechoic tissue was observed

Conclusions These preliminary results suggest that US can be a useful tool for evaluating the tibiofibular joint.

Disclosure of Interest None declared