Hi, Ericka,
Thanks for bringing your question to the Disney Parks Moms Panel. My family has had some experience with worrying about whether or not an injury might limit enjoyment of attractions during our visits to the Disneyland Resort. I am happy to report that the Cast Members at the parks and the attractions themselves are very
accommodating to those with
mobility disabilities. Your son is welcome to use either crutches or a knee scooter in any of the attraction queues. Many attractions will require that he leave the crutches or scooter at the vehicle loading area and that he be able to transfer to a ride vehicle. When the vehicle returns to the loading area, the crutches or scooter will be waiting for him there.
Should your son grow tired of walking with crutches or scooting along on one leg, a limited number of wheelchairs or
electric conveyance vehicles (ECVs) are available for rent. Some attractions in Disneyland Park have queues that will not accommodate wheelchairs for ECVs. For these cases please see a Cast Member for guidance on when and how to enter the attraction either through the exit or a special entrance.
Ericka, I hope your son recovers well and that your family has a magical time!
~Tony