My Acl Knee Replacement Is Now 10 Years Old….how Long Should It Last?

I had my Anterior Cruciate ligament completly renewed back in May ‘96.
One of the first ever done by Mr (Dr) John Fairclough.
I think it’s now stretched and is giving me knee instability.
ie dislocations which bloody hurt…!!
Obviously no excercise can help as it’s an artificial ligamemt.
Question really is should it have lasted forever?
I paid £5000 for the last operation and there is no way I could afford this again!
Also doubt the NHS would operate on an ex. private operation?
Any ideas please?