The former Australia international utility-back was due to join the Saints on a three-year deal earlier this month after seven seasons with Super 15 side Western Force.
However, Northampton pulled the plug on the 28-year-old's move to Franklin's Gardens on medical advice. He has since joined their Aviva Premiership rivals Sale.
Director of rugby Jim Mallinder said at the time: "We obviously monitored Cameron's condition between signing his contract and his scheduled arrival and, after great consideration, felt that on balance we needed more certainty about his ability to handle the tough demands of our long season for the duration of his three-year contract,"
Shepherd's agent issued a statement claiming he was "appalled at the behaviour of Northampton in respect of the manner in which his client and family were treated".
Nick Fordham said: "Expert medical reports from leading independent orthopaedic surgeons and Cameron's former club doctors at the Western Force have concluded that there is nothing wrong with Cameron's ankle."
Shepherd has been troubled by groin and wrist injuries and played just two games for the Force this year.
He made his Super rugby debut with the New South Wales Waratahs in 2004 and played nine tests for Australia between 2006 and 2010.
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.