From the web site link at the bottom:
"Most states have laws that make it illegal to fire an employee solely because the employee has suffered a workplace injury and made a claim. However, an employee may be fired if the injury makes the employee unable to complete the employee’s essential job responsibilities.
The Americans with Disabilities Act (ADA) requires that an employer make reasonable accommodations before firing an employee. For example, the employer may have to create a modified work schedule, provide modified equipment, or restructure the job to meet the needs created by the injury. Most often, employers will make these accommodations if they can be done for a reasonable cost and if the employee only suffers a temporary disability."
http://www.alllaw.com/resources/employment/employee-rights/fired-being-unable-work-due-work-related-injury