Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Pain in the knee following accident could be due to sprain in the ligaments around the joint. There might be soft tissue injury which could have happened following the accident, which would have gone unnoticed. In any case, kindly consult Orthopedician for clinical evaluation. You might require few investigations like x-ray and MRI scan to establish the cause, so that treatment can be instituted accordingly. With conservative treatment, it might take about 4 to 6 weeks for complete recovery. Hope I have answered your query. Let me know if I can assist you further.