Henson will be out for up to six weeks after injuring his hand during the Ospreys’ EDF Energy Cup victory over Harlequins last weekend.
Henson, playing at fly half, scored all the points in his side’s 19-8 win but will be absent for the crucial Heineken Cup Rounds 3 and 4.
The Ospreys faltered in Round 2 with a narrow loss to Gloucester and as a result must record back to back wins over Ulster to keep themselves in the mix for a place in the quarter-finals.
Ospreys Team Doctor Rhydian Lewis said, “Gavin suffered the injury at around the 63/64 minute mark of Sunday’s game after driving into a ruck. From reviewing the match video, it appears that an opposition boot accidentally came into contact with his hand and Gavin can clearly be seen holding his left hand as he gets back to his feet.
“Gavin was able to complete the game, albeit in some pain, and he was checked out immediately after the final whistle by our medical team who diagnosed a suspected fracture of the fourth metacarpal in his left hand. We then secured the earliest available appointment at the Vale Clinic for him to undergo an X-Ray on Monday, where our initial fears were confirmed.
“Understandably, Gavin was keen not to rule himself out and wanted to have as much time as possible to prove his fitness ahead of the weekend, but having received the opinion of a second specialist, he has accepted that he has to allow the bone healing to occur naturally.
“He has now had his left hand set in a lightweight cast and, whilst he will be able to continue with his fitness training, it is expected that he will be unavailable for selection for a period of four to six weeks whilst the bone heals.”
Director of Rugby, Kevin Hopkins added, “After medical consideration it has been decided that Gavin will not be able to take the field for four to six weeks.
“Both Gavin and our medical staff have worked hard in an effort to get him on the pitch against Ulster this coming Friday, but in the end we have decided that Gavin’s long term wellbeing is best served by him getting the hand properly sorted over the next few weeks.”