Fig. 1
From: A practical guide for performing arthrography under fluoroscopic or ultrasound guidance
Commonly encountered difficulties with direct puncture of the radiological joint space. Direct access to the radiological joint space (a) may be impaired by the normal anatomy (spheroid and condyloid joints) (b) and could require repositioning of the limb that may, at times, be challenging (c). Degenerative changes such as joint space narrowing and osteophytes may also hinder a direct approach (d)