To be honest, we get a fair few individuals who are medically discharged, wishing to re-join, particularly from other services.
What they tend to forget is that if they were compensated for a service attributed injury which lead to discharge & in receipt of a tax free 'medical' pension, then certain conditions have to apply for re-joining.
Firstly if they claim to be fully recovered from the condition & the condition itself is not a bar to entry, the question arises "When were they fully recovered?" If fully recovered, "Why are they still claiming a 'medical disability' pension?" The compensation awarded is calculated to take into consideration the injured party cannot be re-employed by the Armed Forces - if they wish to be re-employed, then there's the possibility of having to re-pay some elements of the resettlement package & also the loss of pension if there's no longer a condition which prevents re-joining the service.