An opening-wedge osteotomy is a surgical procedure where a bone is cut partly through and wedged open, in order to re-angle the bone.
Bone graft as an adjunct
Bone grafts may be packed into the opened space, to encourage faster healing of the bone across the new defect.
Closing Verses Opening Wedge High Tibial Osteotomy: an Evidence-Based Review. Ruzbarsky JJ, Dare DM and Marx RG. HSS J. 2015 Oct; 11(3): 291–293.