Anterior Cervical Discectomy with Stand Alone PEEK Cage for Management of 3 and 4 level Degenerative Cervical Disc Disease*

AIM: The aim of this study was to evaluate the efficacy of cage-assisted fusion in three and four level cervical arthrodesis without additional anterior plating in patients with normal bMD. We hypothesized that omitting the use of long anterior cervical plate in multi-level ACDF will simplify the surgery, reduce the surgical time, avoid excessive and prolonged retraction on esophagus and carotids, and will also reduce the potential complications of application of long anterior cervical plate in selected patients. We also thought that the success of stand-alone cage would reduce the cost of the surgery, which is crucial in low-income countries. MATERIAl AnD METhoDS: This prospective case series study included 30 patients diagnosed and treated for multilevel (at least 3 levels) cervical disc prolapse presented by either radiculopathy and/or myelopathy operated by anterior cervical micro-discectomy and stand-alone cage fusion. These cases were treated at Ain Shams University hospitals and Arab Contractors Medical Center between 2008 and 2011. RESulTS: This study included 30 patients; 27 were males (90%) and 3 were females (10%). The presenting symptoms in order of frequency were neck pain (100%) of the cases, followed by radicular pains (70%) and Myelopathy (40%). The mean age of the patients at the time of surgery was 52.23 (minimum 42 and maximum 70 years). 28 patients in our series we operated for three levels (93.4%), and 2 cases we operated for four levels (6.6%). There has been no operative related mortality or morbidity in our series. All the cases were discharged on the first or second postoperative day. We had statistically significant reduction of VAS of arm pains in the immediate postoperative periods. This statistically significant reduction was maintained through the follow up period. There has not been significant correlation between the VAS preoperatively and immediately postoperatively. There has been statistically significant reduction in the VAS of neck pain starting from the third month postoperatively. We had statistically significant reduction of the Nurick score for patients presenting with myelopathy postoperatively. We had solid fusion in 28 patients (93.3 %), and there was no fusion in 2 patients (6.7%). Three cases (10%) needed reoperation. One case operated originally for C3-4, 4-5 and 5-6 disc disease needed reoperation for adjacent segment degeneration at C6-7. Another case developed postoperative discitis after C4-5, 5-6, 6-7 ACDF. A third case developed cage subsidence due to excess removal of the endplate and needed reoperation for corpectomy and fusion and fixation. ConCluSIonS: We recommend that ACDF with stand-alone cage fusion is a safe and effective measure in treatment of 3 or 4 level disc disease with no need of cervical plating in selected patients. We believe that bMD assessment should be added to the routine investigations of patients undergoing fusion surgery as it may change surgical planning. KEy WoRDS: ACDF, multilevel fusion, normal bMD, nurik score, stand-alone cages, VAS *Presented in: Poster presentation in the Congress of Neurological Surgeons, Boston, USA, 2014 Anterior Cervical Discectomy with Stand Alone PEEK Cage for Management of 3 and 4 level Degenerative Cervical Disc Disease 202 World Spinal Column Journal, Volume 7 / No: 3 / September 2016 bACKgRounD C spondylosis is a progressive degenerative disease of the intervertebral discs and adjacent vertebrae. Multilevel affection of the cervical spine represents a challenging problem. A variety of anterior, posterior and combined approaches with and without instrumentation has been advocated. As advanced cervical spondylosis most typically involves compression of the cord by anterior structures, the anterior approach allows for direct decompression of the spinal cord and excision of these pathologic elements. The aim of surgery is to achieve an adequate decompression of the spinal cord, restore or maintain sagittal alignment, achieve solid fusion and avoid kyphosis (15). Reconstruction of the defect after discectomy is still a matter of debate among spine surgeons. Autogenous tricortical iliac graft, artificial disc, PEEK cages and titanium cages, with and without plate application, have all been applied (15). The use of autologous iliac crest bone grafts for fusion has been largely superseded by polyetheretherketone (PEEK) and titanium cages due to the complications associated with donor site pain, blood loss and relatively high levels of graft collapse and kyphosis (14). Anterior cervical discectomy and fusion (ACDF) with plate fixation have been reported to reduce complications of stand-alone cages as subsidence and pseudoarthrosis. Unfortunately, plate related complications rates, ranging from 2.2 to 24%, such as screw breakage, screw pullout, injury of recurrent laryngeal nerve, dysphagia and esophagus perforation still exist (12). There has been a rapid increase in the use of cervical spine interbody fusion cages in view of their theoretical ability to prevent graft collapse, with the potential advantage of indirect foraminal decompression by restoration and preservation of intervertebral height and lordosis (7). An element of clinical equipoise therefore remains in plating as an adjunct to ACDF. In addition, many of the clinical studies looking at anterior plating were in the context of autologous bone grafting and thus the necessity for anterior instrumentation in the context of PEEK cages has not been fully evaluated (14). Recent series have established the safety and efficacy of multilevel ACDF with PEEK cages with and without plating, but superiority of either procedure has not been definitely established (14). Cage subsidence is still an issue with stand-alone cages. Subsidence is defined as the sinking of an object with a greater elasticity modulus (e.g., cage or spacer) into an object with a lower elasticity modulus (e.g., vertebral body) (8). The subsidence rate of stand-alone PEEK cages of the cervical spine was from 5.4% to 19.1% in different studies (3,5,8,17,19). The effect of bone mineral density (bMD) on lumber cage subsidence have been studied and low bMD have been shown to increase the rate of lumber cage subsidence (13). The effect of bMD on cervical cage subsidence have not been studied. The aim of this study was to evaluate the efficacy of cageassisted fusion in three and four level cervical arthrodesis without additional anterior plating in patients with normal bMD. We hypothesized that omitting the use of long anterior cervical plate in multi-level ACDF will simplify the surgery, reduce the surgical time, avoid excessive and prolonged retraction on esophagus and carotids, and will also reduce the potential complications of application of long anterior cervical plate in selected patients. We also thought that the success of stand-alone cage would reduce the cost of the surgery, which is crucial in low-income countries. PATIEnTS and METhoDS This prospective case series study included 30 patients diagnosed and treated for multilevel (at least 3 levels) cervical disc prolapse presented by either radiculopathy and/or myelopathy operated by anterior cervical micro-discectomy and stand-alone cage fusion. These cases were treated at Ain Shams University hospitals and Arab Contractors Medical Center between 2008 and 2011. All patients were evaluated by preoperative complete general and neurological examination. Preoperative investigations included; MRI of the cervical spine, and plain x-rays of the cervical spine (anteroposterior, lateral and dynamic views). bone densitometry for bMD was done using Dual Energy X-Ray Absorptiometry (DEXA). All cases have been assessed for pain using Visual Analogue Scores (VAS) for neck and arm pains preoperatively and at follow up visits. The patients were assessed for myelopathy and their functional outcome using Nurick grades (20). The exclusion criteria were cervical instability or subluxation, patients with kyphotic deformity, and patients with abnormal bone density. All cases had standard approach to the cervical spine with slight distraction using Casper retractor and microscopic discectomy with osteophyte removal. We avoided in all cases