WASHINGTON (AP) - D.C. United midfielder Chris Pontius has had another surgery on his left hamstring.

United said Wednesday that Pontius is expected to miss four to six months.

Injuries have frequently interrupted a promising career that began when Pontius was a MLS Rookie of the Year finalist in 2009. He had injury-shortened seasons in 2010 and 2011. In November, he had surgery to repair his left hamstring and sciatic nerve.

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Pontius had hoped to recover in time for the start of this season, but he had a setback that led to his latest surgery.

Pontius has 27 career goals in six MLS seasons, including a career-high 12 in 2012.

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