I have a bump and line in the middle of my nose after rhinoplasty. How did this happen and can it be fixed? (Photo)

Although it's difficult to provide a definitive answer based on photos alone, it does appear that there is an irregularity in the bone and cartilage of your dorsum.  At 4 months you are still fairly early in your recovery so your nose will change in appearance, so your bridge may or may not improve.  Revision rhinoplasty may be necessary to smooth the contour, but shouldn't be considered until the nose is fully healed.  

Hello,Thank you for your question, and included images.It appears that the transition between the upper lateral cartilages, and the lower lateral cartilages is more pronounced than I would like to see.  This is a particularly complex area, and the best measure of how significant this will be, is best determined after you fully heal.  This may take several more months. I agree with your surgeon's advice to massage and remain patient.Thank you,S.P. Maggi, MD, FACSAustin Plastic Surgery Center 

   It is always difficult to speculate on something of this nature.  There does appear to be swelling, which will mask the nature of what may develop.Kenneth Hughes, MDLos Angeles, CA