Transient osteoporosis of the hip
A small fraction of osteoporosis cases can be classified as transient osteoporosis of the hip. It differs from regular osteoporosis in that it is painful and temporary. Doctors sometimes use it as the last-chance diagnosis if a patient has hip pain and all other diagnoses can be ruled out. In fact, there is usually no indication on X-rays unless the condition is very advanced, in which case osseous demineralization can be seen. MRI scans are more discriminating and can be useful in diagnosis, although MRIs on patients with this condition are often misinterpreted. Laboratory tests typically reveal nothing.
Men actually get this form of osteoporosis more than women. Pregnant women in their third trimester are also at risk. The patient is struck with sudden pain at the hip or nearby and movement is limited as it becomes painful. The pain increases over the course of several weeks. The origin and cause of this condition is unknown. Some theories involve vascular and neurologic systems. A misdiagnosis of avascular necrosis is often given, as doctors may have little experience with transient osteoporosis of the hip.
The cause of the pain is bone marrow edema. This is a build-up in pressure in the middle of the hip bones and subsequent inflammation. Sometimes the condition is accompanied by “reflex sympathetic dystrophy” of nearby tissue, which is in itself very painful.
There is no treatment to forestall or reverse transient osteoporosis of the hip; it goes away on its own in a year. The doctor may advise over-the-counter pain relievers, and may even prescribe a stronger pain reliever. The patient may have to use crutches for the duration. But bisphosphonate drugs are not typically used. The approach is to wait until the disease goes away on its own.
A more broad category is transient regional osteoporosis which includes the hip form. This term - transient regional osteoporosis – is getting more attention as medical professionals are realizing the disease is not just limited to the hip. It is also probably underdiagnosed. The term regional migratory osteoporosis is sometimes employed to describe this phemonemon.
This type of osteoporosis is also likely to occur in joints such as the knee or around the foot. (ankle or metatarsus). Sometimes the condition starts elsewhere in the skeletal system and migrates to a joint. Sometimes the condition occurs on both sides of the body but not always.