Jiyong Gu1, Weiwei Lei2, Zong Xin2, Yi Wu3, Lin Peng2, Zhibin Li3, Zize Feng3, Minchan Zhao4, Songtao Qi5, Yuntao Lu6. 1. Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China; Department of Neurosurgery, Jiangmen Central Hospital, Jiangmen City, Guangdong Province, PR China. 2. Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China. 3. Department of Neurosurgery, Jiangmen Central Hospital, Jiangmen City, Guangdong Province, PR China. 4. Network Information Management Center, Jiangmen Central Hospital, Jiangmen City, Guangdong Province, PR China. 5. Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China. Electronic address: qisongtaonfyy@126.com. 6. Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China. Electronic address: lllu2000@163.com.
Abstract
OBJECTIVE: Fixation with the axis vertebra (C2) using pedicle screws is commonly used to treat an unstable occipitocervical junction; however, it is accompanied by a risk of vertebral artery injury. The occiput-C2 (OC2) crossing translaminar screw fixation technique may avoid this risk, but rod implantation is difficult. Offset connectors can help facilitate this construct. This study aimed to evaluate the stability of a technique for OC2 crossing translaminar screw fixation using offset connectors (C2LAM + OF) in comparison with other methods. PATIENTS AND METHODS: Six fresh-frozen human cadaveric occipital-cervical spines were tested intact under flexion, extension, lateral bending, and axial rotation. These were then made into a type II odontoid fracture model, instrumented with an occipital plate, and tested in the following modes: C2 bilateral pedicle screws (C2P), a single C2 pedicle screw and bilateral C3 lateral mass screws (C2P + C3M), C2 crossing translaminar screws (C2LAM), and C2LAM + OF. The OC2 range of motion (ROM) for each construct was obtained and compared using a repeated-measures analysis. RESULTS: The ROM of the C2LAM + OF construct was found not to be significantly different from that of the C2P and C2P + C3M fixations in every direction (p > 0.05). However, the C2LAM + OF construct was superior to the C2LAM construct in axial rotation (p < 0.05). CONCLUSIONS: OC2 crossing translaminar screw fixation using offset connectors offers similar stability to C2 pedicle screw fixation and is an effective alternative method for treating an unstable occipitocervical junction.
OBJECTIVE: Fixation with the axis vertebra (C2) using pedicle screws is commonly used to treat an unstable occipitocervical junction; however, it is accompanied by a risk of vertebral artery injury. The occiput-C2 (OC2) crossing translaminar screw fixation technique may avoid this risk, but rod implantation is difficult. Offset connectors can help facilitate this construct. This study aimed to evaluate the stability of a technique for OC2 crossing translaminar screw fixation using offset connectors (C2LAM + OF) in comparison with other methods. PATIENTS AND METHODS: Six fresh-frozen human cadaveric occipital-cervical spines were tested intact under flexion, extension, lateral bending, and axial rotation. These were then made into a type II odontoid fracture model, instrumented with an occipital plate, and tested in the following modes: C2 bilateral pedicle screws (C2P), a single C2 pedicle screw and bilateral C3 lateral mass screws (C2P + C3M), C2 crossing translaminar screws (C2LAM), and C2LAM + OF. The OC2 range of motion (ROM) for each construct was obtained and compared using a repeated-measures analysis. RESULTS: The ROM of the C2LAM + OF construct was found not to be significantly different from that of the C2P and C2P + C3M fixations in every direction (p > 0.05). However, the C2LAM + OF construct was superior to the C2LAM construct in axial rotation (p < 0.05). CONCLUSIONS:OC2 crossing translaminar screw fixation using offset connectors offers similar stability to C2 pedicle screw fixation and is an effective alternative method for treating an unstable occipitocervical junction.