How to avoid injecting into tendon substance?

Techniques to Avoid Injecting into Tendon Substance

To avoid injecting into tendon substance, ultrasound guidance should be used whenever possible, as it provides real-time visualization of the needle and ensures accurate placement outside the tendon. 1, 2

Anatomical Considerations

When performing injections near tendons, several techniques can help avoid inadvertent intratendinous injection:

• Identify proper anatomical landmarks before injection to understand the location of tendons in relation to surrounding structures
• Avoid bony prominences by at least 1-2 adult fingerbreadths 1
• Specifically avoid the patellar tendon when performing intra-bone marrow injections 1
• Use the finest needle possible (e.g., 27G or smaller for muscle injections, 30G for bone injections) to minimize tissue trauma 1

Ultrasound-Guided Technique

Ultrasound guidance is the gold standard for avoiding intratendinous injections:

• Use real-time ultrasound visualization to accurately place the needle tip in peritendinous spaces rather than within the tendon substance 3, 4
• Visualize the tendon structure before injection to identify its boundaries and avoid penetration 5
• Monitor needle position continuously during the procedure to ensure it remains outside the tendon 4
• Direct the needle away from tendon substance and toward target spaces (peritendinous, bursal, or intra-articular) 4

When Ultrasound is Not Available

If ultrasound guidance is unavailable, these techniques can help reduce risk:

• Use proper anatomical landmarks and palpation to identify tendon location and borders
• Employ a "periosteum denudation" technique for para-tibial injections, using the finest needle possible (30-31G) to avoid soft tissue injury 1
• Aspirate before injecting - resistance or lack of aspirate may indicate intratendinous positioning
• Feel for increased resistance - injecting into tendon substance typically meets greater resistance than peritendinous spaces
• Inject slowly while monitoring for patient discomfort, which may indicate intratendinous positioning

Injection Setting and Preparation

Proper preparation is essential:

• Ensure optimal setting with professional, clean, well-lit room and appropriate patient positioning 1
• Use aseptic technique for all injections to prevent infection 1, 6
• Consider local anesthetic to improve patient comfort during the procedure 1
• Change needles between drawing medication and injecting to prevent contamination 2

Potential Complications of Intratendinous Injection

Understanding the risks helps emphasize the importance of proper technique:

• Tendon weakening and potential rupture if corticosteroids are injected into tendon substance 1
• Reduced tensile strength of the tissue due to corticosteroid effects 1
• Inhibition of healing in tendinopathies 1
• Pain and inflammation from direct tendon trauma

Post-Injection Care

After successful peritendinous injection:

• Avoid overuse of injected area for 24 hours following injection 1
• Monitor for complications such as skin atrophy, pigmentary changes, or telangiectasias 2
• For diabetic patients, monitor glucose levels for 1-3 days post-injection 1, 2

By following these techniques and utilizing ultrasound guidance whenever possible, clinicians can significantly reduce the risk of inadvertent intratendinous injections and their associated complications.