Fig. 2

Identification of ankle joint line level and landmark for the portable ultrasound assessment

2 A) The tibiotalar joint line is defined using fluoroscopy and labeled with a marker pen

2 B) Two lines are drawn, one along the joint line level (two-headed arrows) and another at about 1 cm below and parallel to the joint line level (thick line). The following line is used as a first landmark for assessing the MCS from the anteromedial aspect of the ankle joint with the middle of the P-US probe positioned on this line and perpendicular to the medial gutter

2 C) The tip of the medial malleolus is identified and outlined using fluoroscopy. The medial malleolar tip, where the furthest distance from the joint line level at which the medial malleolus still articulated with the talus, is used as a landmark for assessing the MCS from the inferomedial aspect of the ankle joint with the middle of the P-US probe placed perpendicular to this landmark

Two-headed arrows represent the ankle joint line level. Thick lines represent the landmark for the anteromedial aspect assessment. One-headed arrow represent the landmark for the inferomedial aspect assessment

(Abbreviations: MCS, medial clear space; P-US, portable ultrasound)