Using tritiated glycine (glycine 3H) as an indicator of amino acid incorporation in protein synthesis in cartilage matrices, Mankin and Conger injected hydrocortisone acetate into rabbit knees. Their data showed a rapid and profound decrease in glycine incorporation that appeared to depend on dosages. Maximum decline was seen six hours after the injection. 28 They did a similar experiment using glycine 14C as the radiotracer, which showed a definite decrease in the rate of protein synthesis within two hours of the injection. They noted that the rate of the inhibitory effect of intraarticular hydrocortisone on cartilage protein synthesis was about twice that of the observed rate for corticosteroids given by intramuscular route. 29 One year later, researchers injected hydrocortisone into normal rabbit knees and produced thinning of the cartilage, and the development of fissures and fibrillations in the articular cartilage. They also found multiple small white deposits within the substance of the articular cartilage, which were found to represent cystic areas of degeneration within the middle zone of the cartilage matrix. These effects were most marked in the animals which had the greatest number of injections. 30 Deleterious effects of cortisone were reported by some researchers who noted that the drug inhibited the synthesis and deposition of chondroitin sulfate in cartilage. 31-33
The purpose of the injection is to provide pain relief and a localized anti-inflammatory effect to facilitate rehabilitation efforts and functional recovery.
Sterile technique is used when performing injections. This added care is needed to minimize the risk of infection.
The material used for the injection is left to the discretion of the physician. Numerous philosophies and theories exist regarding the use of the different injectables. Our physicians use a combination of anesthetic, usually % Sensorcaine and corticosteroid, Kenalog.
Following the injection procedure, it is often helpful to ice the area. The injection itself is traumatic and can result in local swelling and tenderness. Immediate icing of the area reduces this inflammatory response. Heat over the injection site should be avoided for the first 24 to 48 hours or if there is bleeding.
It is important to remember that local anesthetic from the injection may provide significant comfort for a few hours and not to overwork the joint or limb following the injection since there may be increased pain after the anesthetic loses effect. The steroid portion of the injection can take effect within a day or up to two weeks. There may be a delayed response with receiving reduction in inflammation and pain relief following a corticosteroid injection.
Injections provide some degree of relief in the majority of patients. The duration of relief varies. Complications are rare but could potentially result in the need for additional consultation, testing, imaging, procedures and/or hospitalization. Potential adverse side effects from corticosteroids include, but are not limited to, post injection flare, local site reaction, mood swings, rash, itching, hives, difficulty breathing, asthma attack, facial swelling, tongue swelling, headaches, flushing, damage to kidneys, impaired vision or hearing, altered mental capacity, cognitive impairment, increased susceptibility to infection, hyperglycemia, hypertension, injury or potential insult to any body tissue (skin, fat, muscle, connective tissue, and/or bone). Additional questions regarding the potential benefits and risks of an injection as well as corticosteroid side effects can be provided at the time of the injection.
Participants on corticosteroids were 11% less likely to experience adverse events, but confidence intervals included the null effect ( RR , 95% CI to , I 2 =0%). Participants on corticosteroids were 67% less likely to withdraw because of adverse events, but confidence intervals were wide and included the null effect ( RR , 95% CI to , I 2 =0%). Participants on corticosteroids were 27% less likely to experience any serious adverse event, but confidence intervals were wide and included the null effect ( RR , 95% CI to , I 2 =0%).