Legroom is pretty tough to come by at Rangers Ballpark. You have two options. The first is to purchase wheelchair accessible seating. This will have enough room for a wheelchair, but if you are not in a wheelchair, they will provide a seat for you to sit on. This will give you a lot of room. Alternatively, consider purchasing aisle seats on the right aisle in sections far down the line (10-14 or 39-41). If your right leg is the bad one, purchase on the right aisle (higher number seats) in 10-14. If it is your left leg, go with seats on the left aisle (seat 1) in 39-41. This will allow you stretch your leg out in the aisle without too much trouble. Of course, if you have your leg out in the aisle the whole time, you might upset fans moving up and down the aisles (so maybe try to get as close to row 1 as possible). But if you are stretching them every now and again, this is your best bet.