I rec'd a lump sum retroactive disability pension payment in 2018 for 2017 pension funds - Can I amend my 2017 tax return to include the retroactive lump sum payment?

I became disabled effective 4/2107.  Social Security disability approved my claim in 12/2017and in 2018 issued a lump sum retroactive payment dating back to 4/2017. 

Due to social security accepting my claim, in 2018 my employer offered to begin paying disability pension also retroactive to 4/2107.  I received the 2017 disability pension funds in 2018. 

Are there any options to avoid paying taxes for my 2017 disability pension funds on my 2018 tax return?  I do not want to pay taxes on both my 2017 and 2018 pension income on my 2018 federal income tax return.