Aaron Ramsey
Ramsey has had a lot of problems with injuries this seasonReuters

Arsenal boss Arsene Wenger says that he is worried about Aaron Ramsey's persistent injury issues after the Welshman recently picked up another hamstring problem.

The 24-year-old midfielder, who was introduced in the 73rd minute during Arsenal's 2-1 win over Leicester City, was forced off the pitch in just nine minutes after he sustained yet other hamstring injury.

And Wenger, who has to deal with a lot of injuries this season, admits that he is concerned about the Welshman's long-term fitness.

"We haven't found the underlying reason," Wenger told a news conference ahead of the Gunners' FA Cup fifth round clash against Middlesbrough on Sunday. "There is clearly a reason, whether it is medical or biomechanical."

"He is a guy who is serious. He works hard and has a controlled and disciplined life so there is no reason why he should have muscular problems."

The 65-year-old, who insists that the Gunners have not been neglecting Ramsey during training sessions, says that they are still looking to "find the reason" behind the Welshman regular injuries.

"We have individualised training for the players and [injury] prevention for the players and that is not a case that has been neglected. It is just we have to find the reason why that happens. This is just a small injury, a grade one [hamstring tear]. We are looking at a couple of weeks."

Meanwhile, on a brighter note, the Frenchman revealed that Jack Wilshere has returned back to "normal training" after spending almost four months on the sidelines with an ankle injury.

"Jack Wilshere is back in normal training, but he has been out for four months and misses normal competition. He worked very hard, focused, committed, but it will take him a whole to get back to a competitive level," said Wenger, hinting that the midfielder may be featuring against Championship leaders Middlesbrough on Sunday.

"He is motivated to come back as quickly as possible. Competition gives you that sharpness that training cannot give you because it is a combination of fitness and speed of decision-making. It takes a while to get that back."