Steroid-induced ischemic necrosis in the hip: a frequent problem in physiatry

Before I came to study at Regis, I worked for approximately two years at physiatry clinic in Boulder. Some of our most popular treatments were corticosteroid injections into joint spaces and bursae, which can be very effective in the short term for pain and inflammation—we usually expected the results to last between 3-6 months without other treatment (for this reason, a steroid injection was usually followed with a referral to physical therapy for maximum benefit). I saw this treatment used for everything from carpal tunnel to trigger finger to “frozen” shoulders, often with good effect.

However, one use of the steroid injections the doctors were reluctant to use too frequently was in the case of hip joint pain caused by osteoarthritis in the hip. Technically, intra-articular hip joint steroid injections can be effective for arthritic hip pain when a patient is trying to postpone a replacement, but a rare side effect of a steroid injection there is avascular necrosis of the femoral head: complete bone death and sometimes collapse of the femoral head (visible on x-ray). In the time I worked there, I saw this twice, and both patients were subsequently referred out for hip replacements.

Above: Stages of SI-IBN-caused collapse in the hip (source) 

The mechanism behind steroid-induced ischemic bone necrosis (SI-IBN) is not well-understood. A 2014 review by Xie et al hypothesizes that the administration of steroids reduces bloodflow directly, or that it causes an increase in fat deposition resulting in higher pressure on the joint and compression of blood vessels. Steroids are the second most common cause of ischemic bone necrosis after trauma, but it is difficult to predict which patients are at risk simply from their x-rays. A 2009 study in rabbits showed that a functional perfusion MRI (a type of imaging that shows the amount of blood a particular joint is getting) could detect ischemia in bones before necrosis sets in, potentially allowing providers to monitor patients after high-dose steroid administration and to intervene before collapse. 

Providers can minimize the risk of SI-IBN by administering steroids by a low-dose oral route and advising patients to avoid alcohol while taking the steroids and also to consider bedrest during medication but this does not completely remove the risk. Stage I and II SI-IBN hips can be treated with a core decompression or bone graft when the patient is trying to postpone a total hip arthroplasty. Joint replacements are also an option, especially if the patient is older and less active, but for younger, more active patients, the failure rate of a THA is much higher so it is generally advised that providers consider joint-preserving methods first.