Must you rehire a disabled former employee?

Q. One of our employees went on disability after a motorcycle accident. We terminated him at his request, as he wanted to cash out his 401(k). His doctor recently released him from disability, and he's seeking re-employment for a different position. Our owner is concerned that if he doesn't offer the ex-employee a job, we may face legal retribution. And he's concerned that if we do bring him back, we'll end up with a workers' comp claim from a slip/fall injury. Do we have any obligation to rehire this employee? —B.O., Pennsylvania