An increasing number of wheelchair breakdowns are causing people with spinal cord injuries to be left stranded, hurt or unable to keep their medical appointments, according to a new study. In the report, published online in the American Journal of Physical Medicine & Rehabilitation, University of Pittsburgh researchers suggested that changes in Medicare reimbursements may be contributing to this growing problem. The researchers found that more than half of wheelchair users had a breakdown within six months. A growing number of these breakdowns resulted in injuries and other health and safety concerns.