Fracture neck femur cause of non-union?

Ans. is 'a' i.e., Injury to blood supply with shearing stress Causes of non-union in fracture neck of femur are :? Fracture morphology - high fracture angle and increased shear. Displaced fracture grade 3/4. Fracture comminution. Inadequate reduction and stability of fixation. Poor bone quality. Injury to vascularity- direct and tamponade effect. Absence of cambium layer in periosteum. Factors in synol fluid which inhibit the callus formation. Lack of hematoma. Washing away and dilution of osteogenic factors.