HA might have an effect but there is no clinical evidence for it. The cited study by Gabbiani et al (Gabbiani became famous for describing myofibroblasts and also participated in the recent Miami conference) sees an effect on inhibiting alpha-smooth muscle actin. This is no proof that hyaluronic acid helps for Dupuytren's disease just an indication that it possibly might. The role of alpha-smooth muscle actin in Dupuytren's disease is just postulated, not proven, and lab results may well require concentrations that cannot be achieved in a human body.
You might also have a look at the paper by Slack at al http://informahealthcare.com/doi/abs/10....008208209160272 "It is suggested that the behavior of Dupuytren's cells in vivo may result from a response to local conditions within the palm rather than from the expression of an irreversible change in their glycosaminoglycan metabolism."
Wolfgang PS: Our forum has a great search function (see top menu)!