Sebenernya quite common je baby crawl macam tu, tapi since your little one dah 11 months dan still avoiding the knees, better check with your pediatrician just to rule out anything, mungkin dia ada sensitivity or maybe just preference, tapi doc can confirm lah. A few of my mum friends pun pernah alami benda serupa, dan ada yang disappear sendiri once they started walking, but some kena gentle physio check je untuk peace of mind, tak rugi pun tanya!