It depends on where the injection is, 20605 is the elbow JOINT. 20550 is the TENDON SHEATH or LIGAMENT, or FASCIA:. 20551 is the TENDON ORIGIN[/B]/INSERTION. The descriptor for 354.0 carpal tunnel 20526 states 'injection between the tendons of the radial flexor and the long palmar muscles', so I use 20550 for the cubital injection because they inject betweent tendons and muscles with 354.2