The hospital in Toronto is very well known for linear schleroderma.  I do not know if they use UVA1, but it is an excellent starting point.  How old are you?  Have you tried physical therapy to build up the muscle?

http://www.sickkids.ca/dermatology/section.asp?s=Specialty+Clinics&sID=18530&ss=Morphea+%28Localized+Scleroderma%29&ssID=19183&searchTerms=linear%20scleroderma

The lesions are softer and thinner.  I cannot say if the UVA1 caused this or if it was the natural course of the disease.  I think the UVA1 may minimize the collagen buildup while the disease is active so that the symptoms of the disease are less severe than they otherwise would be.  IN some cases it may halt the progression.  I think a lot may have to do with how severe the case is.  His leg is about the same size as his other one.  Length is the same.  Muscle seems the same. The affected limb may be ever so slightly thinner in certain parts especially under a lesion.  I think the reduction would be from a decrease in fat more than a decrease in muscle.  He has only had the disease for 1-2 years so I do not know how the limb will look in 10/20 years. It has been about a year since the end of his treatment and we think we may be seeing signs that the disease is active again. It is very difficult to tell.  I hope that helps.