This general question has been answered multiple times on this site previously. People often ask similar questions about scars and/or piercings on certain meridian lines or points (one reply to this here). The general answer is that while, obviously, you should try to keep all of your organs - the effect on that systems energy is very likely minimal. The base for this answer is that what we call the "spleen" in Chinese Medicine has very little to do with your physical spleen and more to do with a set of complex relationships among multiple organs and multiple functions of the body. The basics of this are explored in my article "My Spleen is What?" - which I suggest you read.
This is true for all of the organ systems - "My Liver is What?", "My Lungs are What?", "My Heart is What?", "My Kidneys are What?".
Now in more technical terms losing an organ does require the body to compensate for that which can put strains on other systems. As you understand how these systems in Chinese Medicine support each other (see five element theory for one view point), you can work with someone to help offset current and/or future issues. This is no different than having a trauma in an area and watching out/working to avoid, arthritis in the area in later years - as an example.