Becker's Spine Review

18 THOUGHT LEADERSHIP ACDF in 10 years: Cervical disc replacement may become gold standard but 'we will always need both' By Alan Condon A nterior cervical discectomy and fusion is the most common surgery for treating symptoms related to a degenerative or her- niated disc in the neck, but other techniques may offer more benefits to patients, depending on their spinal condition. However, in recent years, cervical disc replacement — in which an arti- ficial disc is inserted to maintain motion between the vertebrae — has gathered momentum and could become the standard of care for treating degenerative cervical disease, according to many surgeons. irteen spine surgeons from health systems and private practices across the country discussed how ACDF and other treatment options will evolve for cervical pathology over the next decade. Question: How do you expect ACDF to develop over the next 10 years? How will it compare to other types of spinal fusion? Venu Nemani, MD, PhD. Virginia Mason Franciscan Health (Seattle): Almost certainly, the rates of ACDF will decrease over the next 10 years as cervical disc replacement technologies continue to evolve and the indications for disc replacement are expanded. However, ACDF will always be a critical tool in the cervical spine surgeon's toolbox to deal with pathology that warrants spinal fusion (deformity, instability, etc.). Although there will continue to be innovation in interbody and bi- ologic technology, the real change will come in more clearly understand- ing when our operations need to correct cervical malalignment versus just treating the neurologic problem (radiculopathy, myelopathy). is will depend on further research to better understand what consti- tutes normal versus abnormal radiographic alignment in the cervical spine, how patient-reported outcomes correlate with restoration of nor- mal cervical alignment aer ACDF and the development of improved tools for surgical planning. We now have a good grasp of our alignment goals and its effect on outcomes when performing lumbar fusion, but I believe we will greatly improve our understanding of this with regard to cervical surgery over the next 10 years. Kee Kim, MD. UC Davis Health (Sacramento, Calif.): We have wit- nessed tremendous advances in treating patients with cervical degener- ative disc disease in the last two decades. ACDF has been an integral part of improved patient care. I have been privileged to be a part of innova- tions in cervical artificial disc and zero-profile cage technology. ACDF will continue to be popular compared to other types of spinal fusion, but I expect the following changes to occur over the next decade: 1. More ACDFs will be performed in the ambulatory setting. 2. More ACDFs will utilize zero-profile cages with integrated screws instead of cervical plates due to ease of use and reduction in adjacent segment disease. 3. ACDFs will decrease proportionally due to an increased use of cervi- cal artificial discs. 4. More artificial disc surgery failures will be seen due to increased patient demand, less strict indication for its use, suboptimal surgical technique and greater awareness of periprosthetic osteolysis. erefore, more ACDFs will be performed to revise failed artificial disc surgeries. Praveen Mummaneni, MD. UCSF Health (San Francisco): e analysis of the cervical cases in the Quality Outcomes Database of the American Spine Registry shows that ACDF dominates over posterior fusion in the sheer number of cases done annually. is is not surprising as ACDF is very efficacious for one- and two-level disease. Currently, most posterior cervical fusions are done for patients with three or more levels of stenosis — to avoid dysphagia from multisegmental retraction on the esophagus — and this trend is likely to continue. ACDF is likely to be done more frequently than posterior cervical fusion in the years to come. ACDF, unlike posterior cervical fusion, has already partially shied to out- patient surgery for one- and two-level cases in healthy patients. However, those with comorbidities still have the ACDF done inpatient. In the future, I suspect that most ACDF cases will go to the ASC as the efficiency of the surgery centers is much better than the inefficiency with turnover that many of us experience on the inpatient side. Likely the inpatient setting will be reserved for the patients with comorbid conditions (sleep apnea, heart disease, etc.) or revision ACDF who need close observation post-op. Finally, in the future, hybrid constructs with ACDF and arthroplasty may increase in number. Currently, insurance approval limits these hybrid cas- es, but when patients have nonadjacent disc herniations, a hybrid con- struct where intervening normal levels are skipped makes a lot of sense. Lali Sekhon, MD, PhD. Nevada Neurosurgery (Reno): Anterior cervical fusion has been around since 1955 but every five to 10 years undergoes a change in technique, implants and materials. It's not going away. I started cervical arthroplasty in 2002 and the indications for a successful cervical arthroplasty are still tight (less than 50 percent loss of disc height, motion at treated level, no facet disease, etc.). When we wander from those initial indications, our results are less certain. Longitudinal studies on cervical arthroplasty have also shown those patients are not immune to adjacent segment disease, just less so. ACDF will still be here in 10 years. Our understanding of stiffness and the effects on adjacent segment dis- ease are only just starting. ere is a middle ground between fused solid and totally mobile, but today that is a dimension that we can't appreciate. e concept of a "so fusion" is something that makes no sense, but it may in the future as we discover materials and constructs less stiff than cancellous bone. ACDF is not going away. Just as the last 65 years have seen us move from dowels to allogra to PEEK to porous titanium, the continuum of change will continue and the gap between arthroplasty and current spinal fusions will blur. Kris Radcliff, MD. Rothman Orthopaedic Institute (Philadelphia): Operative microscopes will become a dominant technology in ACDF. In addition to the usual ergonomic and practical reasons to use a micro- scope (lighting, assistant, etc.), the newer microscopes incorporate exo- scope features and built-in endoscopes. Working on a view screen will be appealing to the next generation of surgeons who have grown up with gaming systems. Newer microscopes will also incorporate built-in navi- gation and physiological imaging beyond the visual spectrum including fluorescence. Surgeons will be able to see the recurrent laryngeal nerve, for example. Ultimately, the technology will make the surgery safer. I also expect that robotic bone resection with predefined boundaries and safe zones will become commonplace. Our colleagues in arthro- plasty have already demonstrated that robotic bone removal technology standardizes surgery and improves reproducibility. Even in experienced

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