The Dutchman's season is now over due to the setback.
Howe said, "It's a big blow. It's a complex story with Sven. Initially he had a partial tear (earlier this season). We sought specialist opinion and there was conflicting reports on what he should do next.
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"Ultimately, our medical team advised him to get surgery, but he wanted to carry on. He has then aggravated that issue.
"He now has a long road ahead of him, but the operation went well so we hope he comes back in a better place. Now we'll support him and help him back."
On Lewis Miley's injury suffered with England U20, Howe said: "Lewis has come back to us with a back problem, we are seeking specialist opinion on him, we don't know exactly what it is right now."