There seems to be non union of tibia with intrameduallary nail in situ.
What complaints is he having at present.
There is a big gap between the fracture ends. Bone grafting usually helps in providing the track for better bone healing.
Next Steps
There is a possibility that the fracture won't unite on its own in such situation. It may require further procedure.
Health Tips
Continue Physiotherapy for now and medicines which will help in bone healing.