Arthrocentesis – Also called joint fluid aspiration, arthrocentesis is removal of joint fluid through a hollow needle inserted into the joint space of the knee. Although the purpose of removing joint fluid from the knee is usually so that it can be tested in the lab, removing excess fluid can also quickly ease pain and swelling. Often after withdrawing fluid, doctors use the same puncture site where the fluid was removed to inject a corticosteroid preparation and/or anesthetic into the knee joint to further relieve pain and inflammation.
Although epidural steroid injections (also called epidural corticosteroid injections) may be helpful to confirm a diagnosis, they should be used primarily after a specific presumptive diagnosis has been established. Also, injections should not be used in isolation, but rather in conjunction with a program stressing muscle flexibility, strengthening, and functional restoration.
Epidural injections and intradiscal injections have been used in the treatment of non-radicular degenerative disc disease with limited success. Proper follow-up after injections to assess the patient's treatment response and ability to progress in the rehabilitation program is essential. A limited number of injections can be tried to reduce pain, but careful monitoring of the response is required prior to a second or third injection.
However, a randomized, placebo-controlled, double-blind study by McAlindon et al found that in patients with knee osteoarthritis, intra-articular corticosteroid injections (40 mg of triamcinolone acetonide, administered quarterly over 2 years) led to an increase in cartilage loss and was associated with less pain reduction than placebo injections. The study determined that the mean change in index compartment cartilage thickness in the corticosteroid patients was about twice that of the placebo subjects. (The investigators stated, though, that due to the timing of pain measurements, the study could have missed transient pain reductions in the corticosteroid group.) [ 18 , 19 ]