Extra-articular injection

Extra-articular injections occur when the needle tip is not within the targeted joint during joint injections.

Terminology

Defined by the presence of contrast outside of a joint in fluoroscopic or CT guided procedures, or the lack of direct visualization and resisted flow of intra-articular injectate during ultrasound-guided procedures.  

Differential diagnosis

• adhesive capsulitis 

Practical points 

• extra-articular injections should be identified when performing image-guided joint injections, to avoid subsequent injection of either arthrogram solution or steroid containing injectate outside of the joint
• during fluoroscopic guided procedures, straight or linear spread during injection of contrast should alert the practitioner to an extra-articular injection
• often extra-articular injections will have resistance and can be uncomfortable for the patient
• adhesive capsulitis can cause resistance and poor joint capsule distension ¹
• the needle tip should be visualized throughout ultrasound-guided procedures to ensure accurate placement ²
• patient positioning can dramatically change the ease of access into the joint i.e. supinated hand during anterior glenohumeral joint injections
• the benefit of achieving and confirming an intra-articular facet joint injection is debated, as periarticular injections have been shown to have equivalent outcomes as intra-articular injections ³