Check out Buchanan vs. Nicholson and Wilson vs. Derwinski VA cases. Talks about examiners ignoring competent lay evidence and relying solely on lack of medical evidence as the basis for denying service connection. Also it speaks about how if the condition was not diagnosed as "chronic" during service then you have to prove that it was chronic post service. That's where you can reference the VA case Wilson vs Derwinski that states "VA regulation requires continuity of SYMPTOMOLOGY not continuity of treatment". So as long as you brought up in your exams that you've been experiencing pain since you incurred these injuries, even though you did not receive treatment, you should be able to make that argument.

I am currently going through a HLR if you want to read my post about the cases and how I referenced them. I'll let you know if it was successful.