A novel bicortical alternating screw exchange lagging technique for reduction of cervical spinal deformity

Cervical kyphosis in the presence of multilevel disc degeneration poses a significant challenge to surgical correction. Anterior cervical discectomy and fusion (ACDF) is a well-established approach to decompress the neural elements and relieve pain but may not specifically correct kyphosis. We describe an anterior only ACDF approach utilizing a novel lagging technique (Vanni technique) to correct cervical kyphosis. The objective is to reestablish lordosis without adding the morbidity of corpectomies or posterior osteotomies. The ACDF procedure with the lagging technique is summarized in the following steps: (1) multilevel discectomy, (2) lordotic interbody cage placement at each level, (3) lordotic plate positioning secured by a temporary pin, (4) bicortical screw placement bilaterally at each level using a screw exchange lagging technique, allowing the vertebral bodies to be sequentially translated toward the plate using progressively shorter bicortical screws until flush, and (5) final screw tightening and locking to the plate. In two illustrative cases, patients underwent anterior cervical discectomies and fusions from C3 to C7 using the Vanni lagging technique to correct deformity. Postoperative follow up showed improvement in Sagittal Vertical Axis (SVA) and lordosis with solid fusion. The current technique report provides a detailed description of a multilevel ACDF procedure with a novel lagging technique to effectively correct cervical deformity. It obviates the need for more extensive and morbid corpectomies and osteotomies in selected patients with reducible deformities.