I have used 20550 for tennis elbow injection in the past, because the documentation does not describe the injection at the tendon origin of the extensor carpi radialis brevis but just at the tendon in general. The below example from AMA CPT Changes supports 20551 because of the identification of the tendon origin site as the place of the injection.
In regards to 2 injections at tendon origin sites in the knee. The note would have to have documentation of separate tendons at separate tendon origin sites.
Below is from 2004 AMA CPT Changes
▲20550 Injection(s); single tendon sheath, or ligament, aponeurosis (eg, plantar “fascia”)
▲20551 single tendon origin/insertion
▲20552 Injection(s); single or multiple trigger point(s), one or two muscle(s)
20553 single or multiple trigger point(s), three or more muscle(s)
(If imaging guidance is performed, see 76003, 76393, 76942)
Rationale
The injection codes 20550-20553 have been revised to clarify the intent of these codes, as related to multiple reporting of these services. In addition, the tendon injections and trigger point injections have been separated into two code families.
The tendon injection codes 20550 and 20551 are intended to be reported for multiple injections per single tendon sheath or ligament. Thus, multiple injections to the same tendon sheath or ligament would be reported only once per session, while injections to multiple tendon sheaths, tendon origins, tendon insertions, ligaments or aponeuroses would be reported for each injection. Code 20550 was also revised to include anatomical language in the descriptor.
The trigger point injection codes 20552 and 20553 are intended to be reported once per session, regardless of the number of trigger points or muscles injected.
Clinical Example (20550)
A 50-year-old woman presents with stenosing tenosynovitis of the right index finger which is treated with a steroid injection into its flexor tendon sheath.
A 46-year-old female diagnosed with plantar fasciitis, who has failed to respond to NSAIDs, modifications in shoe gear and stretching exercises, presents with plantar fasciitis of the right foot which is treated with a steroid injection into the plantar fascia.
Description of Procedure (20550)
The proximal edge of the A-1 pulley of the right index finger is located. The injection is given into the flexor tendon sheath.
The medial and lateral tubercles of the calcaneus are palpated and the point of maximum tenderness is identified. The medial and central bands of the plantar fascia are localized. A medial approach is utilized and the injection is given superficial to the plantar fascia.
Clinical Example (20551)
A 35-year-old man is treated for lateral epicondylitis with an injection into the origin of the extensor carpi radialis brevis (ECRB) on the lateral epicondyle.
A 35-year-old man is treated for peroneus brevis tendonitis of the left foot with an injection into the insertion of the peroneus brevis tendon at the base of the fifth metatarsal.
Description of Procedure (20551)
The region of the insertion of the ECRB on the lateral epicondyle is localized and injected.
The region of the insertion of the peroneus brevis tendon on the base of the fifth metatarsal is localized and injected.
Clinical Example (20552)
A 60-year-old female presents with a 3-month history of pain in the low left back above the posterior iliac crest with radiation of pain into the left buttock. Muscle relaxants, NSAIDs, and physical therapy have been ineffective in relieving her pain. She undergoes injection of the trigger point in the multifidus muscle left of the L5 spinous process.
Description of Procedure (20552)
After identification of the trigger point in the multifidus muscle left of the L5 spinous process by palpation, a needle is inserted through the skin into the muscle. The needle is advanced a short distance, about 2 to 4 centimeters, observing for any complaints of paresthesias but searching for the area of maximum tenderness. If any complaints or paresthesias are encountered, the needle is withdrawn slightly until they stop. Next the injectant solution is infiltrated in a fanwise method into the trigger point after aspiration is negative for blood.