Suggest Treatment To Straighten Leg After Plaster Is Taken Off

my son has osteoporosis in february he had a fracture just above his knee not a total fracture just a crack and was treated in a cast for about 9 weeks plaster is off now the problem is his leg is still in the position the way the plaster was i mean still slightly bended and when he walks he doesnt put his heel down to balance with other leg, hope this makes sense, its been long time and i am concern about this what are the options of straightening the leg. Thank you