I have transverse myelitis, i have been doing physio for 14 months, but when i walk my right knee just collapses forward as soon as i weight-bare why?

UMN weakness: Upper motor neuron weakness from inflammation injury of the spine (transverse myelitis) typically causes spastic weakness: even though the muscles are tight and may at times cramp or spasm, they are still weak b/c the brain lost control over voluntary movement of affected muscles. Ask about adding neuromuscular electrical stimulator (nmes) to rehab routine. Good luck!