Corticosteroid injections are commonly used for the symptomatic treatment of knee osteoarthritis. Common practice is to inject the joint with a combination of corticosteroid and local anesthetic, with the rationale of providing longer duration pain relief with the corticosteroid and immediate, though short duration relief with the anesthetic. However, multiple in vitro and animal studies have shown that local anesthetic may be harmful to chondrocytes. Despite this data, use of intra-articular anesthetic remains widespread. Many clinicians believe incorporating the anesthetic is important because it can provide immediate pain relief and facilitate patient confidence in the treatment program. However, there is no published data to validate this reasoning. Therefore, the anesthetic has unknown clinical benefit and may have adverse effects on articular cartilage. In light of this, the investigators question the routine use of anesthetics in joint injections. The purpose of this study is to compare the effects of knee joint injections using: 1) corticosteroid with local anesthetic versus 2) corticosteroid with normal saline.

Inclusion criteria:

1. Age 18 or older
2. Knee osteoarthritis (uni- or bilateral) as defined by the American College of Rheumatology (staged by Kellgren-Lawrence radiographic grading scale)

Exclusion criteria:

1. Rheumatologic/inflammatory disease
2. Metabolic bone disease
3. Crystalline arthropathy
4. Current smoking
5. BMI > 40
6. Knee injection with corticosteroid or viscosupplementation within previous 6 months
7. History of knee prolotherapy, platelet rich plasma or cellular (stem cell) injection
8. Knee surgery within the last year
9. Chronic opioid use
10. Chronic pain syndrome/fibromyalgia
11. Pain behavior during the clinical encounter as judged by the injecting physician
12. Physician specifically ordered injection of corticosteroid/anesthetic or other specific combined corticosteroid injection
13. Diagnostic uncertainty by referring provider
14. Referral for bilateral knee or multiple joint injections (*note that arthritis involving multiple joints alone is not an exclusion criteria, only the patient receiving more than 1 injection)

3 months

Lack of power due to lower than expected enrollment; follow-up was limited to 3 months.