One diagnosis that comes to mind is Legg-Calve-Perthe's disease. This a disorder of boys aged about 8-10 of unknown cause, and involves 'aseptic necrosis' (lack of blood supply causing degeneration) of the femoral heads (top of the leg bone that fits in to the hip). This causes hip and/or knee pain bilaterally. One can see some joint space widening on plain xray but ,ay not. MRI should reveal the diagnosis and should be done as soon as possible. Infection in the hip joint should always be considered and excluded. Pain in the hip and lateral leg area can come from a pinched nerve ni the lower back and this can be tested for clinically, if suspected an MRI of the lower spine is indicated.
A problem in the hip can cause pain in the knee because of the similar sensory innervation. Other that this fact there is no primary neurological diagnosis to be considered.
Good luck
Good luck finding a solution. I hope your son feels better soon.
Thankfully, this round is over, and he is back on his feet. I hope we figure this out soon!
I do pray that the doctor's find the cause of your son's pain and he gets some relief.
Jeanne
I am happy to hear that you son is feeling better at this time. And I wish him luck during his mri. If you need any more info, you can email me at ***@****.
Jeanne
Good luck
Em