Speaking at the Cardiff Blues training centre, Deiniol, said:
"I had an operation on both shoulders in November because they were getting too painful for me to continue playing and there was quite a bit of damage in both of them."
"After rehab, one shoulder has improved pretty well but the other one is at the stage where there is no hope of getting back to the strength and stability needed to play rugby."
"So, the advice I have been given by the surgeons is that I have to retire from the game."
"It has been a massive blow for me and it's a hard pill to swallow at the moment."
"However, if I take a step back and look at what has been achieved in the eight years I have been here at the Blues, then I am really proud to have been part of the development and progress that has been made."
"When I look back to when I joined it was totally different."
"We were training on a school pitch, we didn't have our own gym and the organisation wasn't really in place."
"Now we have the facilities and all the necessary departments in place, which are fantastic. I am privileged to have been a small part of that."
"I have many great memories of my time with the Blues."
"There are the obvious ones like winning silverware. It's what you aspire to when you play sport and the two competitions we won really do stand out."
"However, looking back, the thing I treasure more than anything at the Blues is the relationships you build and friendships you make with players, coaches, with medical staff and all those involved off the field."
"That is the one thing I will miss more than anything."
"There are a number of people I'd like to thank, from all the medical staff who have looked after me, in particular my surgeon, Richard Evans, and Tim Atter, who has kept me taped together for years, to my current and former team mates. I'd also like to thank everyone who works at the training centre and the stadium, especially Mike Bieri and Vicky McCracken who keep the organisation together, and of course all the supporters, who have been great to me since I joined."
Looking forward to life after rugby, Deiniol, said:
"I have my own business, J&D Water Consultants, which is a water treatment and hygiene company that has been running for five years now."
"My business partner and I set up the company five years ago and started off working from his house. We have now expanded with a unit in Bridgend and things are progressing well."
"We are working all over the UK and the company is evolving. It's a great challenge and one I am really looking forward to throwing myself into."
Even though Deiniol is hugely knowledgeable and has a wealth of experience, coaching isn't something that appeals at the moment:
"I have been a professional rugby player now for 16 years and in my opinion, being a rugby coach requires twice the commitment of being a player," added Deiniol.
"I have a young family and I would like to spend weekends with them now and appreciate my kids and my wife."
"To be a top coach, you have to put in an incredible amount of commitment to be successful. To maintain that intensity after being a player is something that I don't think is healthy to do immediately."
"I think it's healthier to take a step back and do something else in life."