“The MLS cardiology consultant and a heart specialist at MedStar Georgetown University Hospital determined that he could resume playing,” said DC United’s General Manager Dave Kasper.
“The player had a potential cardiac issue that could have eliminated him from playing. He was evaluated and found this not to be the case.
“We went through proper medical testing and approvals from two top cardiology specialists.
“Certainly we went through a rigorous process, but once they cleared him to play, it gave us peace of mind.
“Kamara will undergo testing at the end of each season.”
A transfer fee has not not been paid for Kamara but Norrköping will be compensated if the player meets performance incentives or sold in the future.
He was originally examined as part of a Uefa requirement because IFK Norrkoping are due to take part in the qualifiers for next season’s Champions League.
Experts from both Uefa and Fifa had advised Kamara against continuing playing football.
This forced Norrkoping to remove Kamara from their 2016 season squad to stop him from playing more matches.
But further examinations carried out by Cardiologists in the United States have now revealed that Kamara has no cardiac issue.
Kamara who scored six goals to help Norrköping win the 2015 Swedish league is delighted that his career has been given life again.
“Kamara is so happy and excited to be able to play again,” Kamara’s local agent Chernor Musa Jalloh told BBC Sport.
“Physically and mentally he is prepared and he knows everything as he is a strong guy.
“He went through a difficult path and thanks to everyone who supported him.”
Kamara is not expected to play in MLS immediately because he’s not match fit.
His move to DC United comes at a time when two Cameroonian players Patrick Ekeng andJeanine Christelle Djomnang died of suspected heart problems.
The former Kallon FC marksman is the third Sierra Leonean to join DC United after Abdul Thompson Conteh and Ibrahim Koroma who didn’t play a single match for the MLS club.