Joint injections or aspirations (taking fluid out of a joint) are usually performed with a cold spray or other local anesthesia in the office. After the skin surface is thoroughly cleaned, the joint is entered with a needle attached to a syringe. At this point, either joint fluid can be obtained (aspirated) and used for appropriate laboratory testing, or medications can be injected into the joint space. This technique also applies to injections into a bursa or tendon sheath to treat bursitis and tendonitis, respectively.