1.Severe varus/valgus deformity with severe flexion contractrue,and need to release bilateral accessory ligaments completely.
2.Severe and uncorrected imbalance of flection gap,and lead to cam separation in non-limited design.
3.The patient has neuromuscular disease.
4. The extensor mechanism function is damaged.
5. Severe retroflexion deformity
6. Bone tumor patients