Shrewsbury defender Mike Jackson has been forced to retire after being out for 11 months with a knee injury.The 36-year-old, who joined from Blackpool in 2008, will stay at Town in a coaching role at least until May. [LNB]He told BBC Radio Shropshire: "I'm gutted. I've tried everything but it's got worse. Playing again could have meant a complete knee cap replacement. [LNB]"I also feel embarrassed. I was brought here to play, the club invested money in me, and I've lasted half a season." [LNB]He continued: "It's been hard from a footballing point of view but also from a family point of view. [LNB]"I've got two young children and I've[LNB] [LNB][LNB] not been able to play with them and go out with them like a normal person would do. [LNB]"I've spent so long on crutches, and I tried to step it up recently, but the bone specialist says the knee can't take it. [LNB]"The decision was inevitable, but also a hard one. Football's something I've done all my life, and is something I love doing. I've had a good career - but I've got to move on. [LNB]"The manager (Paul Simpson) has been brilliant with me. He's given me the opportunity to be involved with the coaching side of it, and that's my next goal - to be a top coach, a manager.[LNB] He'll continue to work on the coaching side here, which is good news for the club Manager Paul Simpson "I've done my coaching qualifications, and this could be a new start. [LNB]"You can either sit and wallow in it, like I probably will for a couple of days, or you get on with it. [LNB]"I'm thankful I've had the opportunity to play football and now I want to move on and do something I'm passionate about as well." [LNB]Jackson made his debut for Crewe in the 1992-93 season, and later had long spells at Preston, Bury, Tranmere and Blackpool - clocking up more than 600 appearances in his professional career. [LNB]"It's a massive disappointment for Jacko, but he's got to look to his long-term health," said Shrews boss Simpson. [LNB]"He'll continue to work on the coaching side here, which is good news for the club. He has the respect of all the staff and players."