Changes in Sagittal Alignment After Cervical Disc Arthroplasty: Results of 24 Month Pilot StudyKemal Yücesoy1, Kasım Zafer Yüksel2, Mürvet Yüksel3, Orhan Kalemci1, İdiris Altun2
1Dokuz Eylul University, Neurosurgery, Izmir, Turkey
2Kahramanmaras Sutcu Imam University, Neurosurgery, Kahramanmaras, Turkey
3Kahramanmaras Sutcu Imam University, Radiology, Kahramanmaras, Turkey
Background Context: For cervical disc replacements to be comparable to the gold standard of cervical discectomy and fusion (ACDF), disc replacements must be able to provide motion as well as predictable and reliable correction of cervical alignment. The Synergy Disc was designed to provide alignment correction in the sagittal plane while restoring physiologic range of motion.Keywords: sagittal balance, kyphosis, cervical arthroplasty; cervical sagittal alignment; Synergy Disc, kinematics, center of rotation, artificial disc
Purpose: This study evaluated whether the Synergy Disc provided preservation and/or restoration of sagittal alignment while normalizing kinematics and providing acceptable clinical outcomes. The alignment provided by the Synergy Disc was compared with a retrospective cohort of 30 single level ACDF patients
Study Design/Setting: The pilot trial was a multi-center, prospective, consecutive patient enrollment study using the Synergy Disc for the treatment of single and two-level degenerative disc disease of the cervical spine.
Patient Sample: The procedure was performed on 43 patients (45 implants) with follow-up on 40 patients (42 implants). For the historical cohort ACDF arm, 30 patients with similar follow-up with single level anterior discectomy, fusion and plating were used for segmental lordosis measurements.
Outcome Measures: For the Synergy Disc group, the kinematic outcome parameters included: range of motion (ROM), shell angle (SA), disc height (DH), sagittal plane translation and center of rotation (COR) in the X and Y direction. Standard assessments of clinical outcomes were also measured (Neck Disability Index, Visual Analog Scale). For the fusion arm, only functional spinal unit (FSU) angle was recorded using a single pre-operative and post-operative standing lateral cervical radiograph
Methods: In the Synergy Disc group, static and dynamic radiological assessments were performed in 43 consecutive patients prior to the placement of the Synergy Disc. Forty patients were studied for the course of the study protocol (3 patients lost to follow-up). For the Synergy Disc group, lateral cervical radiographs were evaluated for ROM, translation, COR, DH and SA before and at the longest follow-up post surgery. Neck Disability Index and Visual Analog Scale for arm and neck pain were collected and analyzed. For the fusion group, standing lateral radiographs were reviewed.
Results: At a mean of 28 months with all patients having a minimum of 24 month follow-up (40 patients, 42 implants), the average SA of the Synergy Disc was maintained at 6 ± 2.7° of lordosis. Pre-operative ROM, translation and COR X did not change significantly following surgery. There was a significant superior shift in the COR Y. There was significant improvement in all clinical outcome measures. In the fusion group, with a similar follow-up period, there was a 4° increase in lordosis at the FSU.
Conclusions: The Synergy Disc provided lordosis at the surgical level, while maintaining pre-operative ROM, translation and COR X. The lordosis of 6 ± 2.7° provided by the Synergy Disc at 2 years following surgery was comparable to the lordotic correction provided by an anterior cervical discectomy with interbody fusion and plating.
Kemal Yücesoy, Kasım Zafer Yüksel, Mürvet Yüksel, Orhan Kalemci, İdiris Altun. Changes in Sagittal Alignment After Cervical Disc Arthroplasty: Results of 24 Month Pilot Study. Sinir Sistemi Cerrahisi Dergisi. 2016; 6(1): 1-9
Sorumlu Yazar: Kasım Zafer Yüksel, Türkiye