Fig. 2

Surgical technique (A–F). A The extension gap was evaluated for size and balancing by a traditional spacer block. B The modified spacers were inserted in the joint space of the knee at 90° of flexion, and the tension of the medial and lateral ligaments were balanced. C The condyle measuring device determines the size of the femoral prosthesis and the AP position of the 4-in-1 resection block. D Use the AP axis as an additional visual reference to confirm the external rotation resection. E Install the 4-in-1 resection block. F A well-balanced flexion gap equal to the extension gap was obtained