The Brazil international, who left the pitch in tears at half-time, was on crutches after twisting his ankle in Newcastle’s 1-0 win over Fulham, leaving United concerned he could be facing a lengthy absence.
And manager Howe revealed Guimaraes was still upset after the final whistle, saying: “He’s a bit distressed about his injury. It’s his ankle and he twisted quite badly, I think. He’s very upset and we’re obviously concerned for him. We hope it’s not too serious but at this moment in time, we don’t know.”
Guimaraes had been hurt after 18 minutes in a challenge with Fulham’s Joao Palhinha and Howe admitted he should have taken him off sooner.
“With hindsight, yes, but the player wanted to stay on and I always want to go with the player,” he added. “They know their bodies better than I do. Bruno was determined to carry on. I think he wanted it strapped because of slight discomfort. It was only with about 30 seconds to go in the first half that he signalled to come off. He played every well in the first half.”
Newcastle are yet to make a signing in January and Howe feels they may need reinforcements in midfield.
He said: “We will see. I will first assess the injury. We are light in midfield. We were missing Elliot [Anderson] so we will get the diagnosis on Bruno and then make a decision.”
Howe defended his decision to select Joelinton, three days after he was charged with drink-driving.
He explained: “I had a long meeting with my coaching staff on Saturday afternoon after training where we debated the whole scenario. I had to make the decision. I didn’t underestimate what Joe did but there are a whole host of things to consider.”