CRPS can cause Osteopenia several things play into why this occurs. The main two are lack of blood flow and disuse. Are you taking vitamin D3?

Here are two snippets of info from one of the most well known experts in CRPS, Dr. Hooshmand: (Full link to article: http://www.rsdrx.com/CRPSABSTRACT.htm )

INACTIVITY

If at all possible, the CRPS patient should not be hospitalized unless it is absolutely necessary (such as for emergency surgery). The usual hospital policy of enforced bed rest aggravates the CRPS. The inactivity results in up regulation and activation of the sleeping nociceptors (deep chemoreceptors in bone and muscle), with secondary deep, intolerable pain. The patient is instructed to stay in bed no more than 8-9 hours a night and to try to walk before going to bed. If sitting or laying down cause pain, the patient is instructed to get up and move around. If walking or any type of exercise causes pain, the patient is to rest frequently. Treatment of osteopenia requires ambulation and weight bearing. The use of wheelchair, walker and other assistive devices should be discontinued.

TREATMENT OF OSTEOPENIA

Osteopenia, usually transient, is a common complication of CRPS. Most commonly, it affects the hip, foot, shoulder, and wrist areas. Treatment consists of combination of weight bearing, mobilization, estrogen replacement, biphosphonates, and diet rich in calcium (e.g., cabbage, and dairy products). Mobilization is the most indispensable form of treatment.