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Background Context Anterior cervical discectomy and fusion (ACDF) is a very common operative intervention for the treatment of cervical spine degenerative disease in those who have failed non-operative measures. However, studies examining long-term follow-up on patients who underwent ACDF reveal evidence of radiographic and clinical degenerative disc disease at the levels adjacent to the fusion construct. Consistent with other junctional regions of the spine, the cervicothoracic junction (CTJ) has significant morphologic variations. As a result, the CTJ undergoes significant static and dynamic stress. Given these findings, there has been some thought that ACDF down to C7 may experience additional risks for adjacent segment degeneration/disease (ASD) when compared with ASDFs that are cephalad to C7. Purpose The goal of this study is to evaluate the rate of radiographic and clinical ASD in patients who have undergone single- or multilevel ACDF, down to C7. Study Design This is a retrospective cohort study. Patient Sample The sample included consecutive patients from a single orthopedic surgeon at one quaternary referral medical center who underwent an ACDF between January 2008 and November 2014. Indications for surgery included radiculopathy, myelopathy, or myeloradiculopathy in the setting of failed conservative treatments. Patients were excluded if they had an ACDF of which the caudal level was cephalad to C7 or if they had undergone a previous cervical fusion. Outcome Measures Radiographic diagnosis of ASD was determined by the presence of disc space narrowing >50%, new or enlarged osteophytes, end plate sclerosis, or increased calcification of the anterior longitudinal ligament (ALL). Postoperatively, data were collected on the presence of new radicular or myelopathic symptoms indicative of pathology at C7–T1, indicating a diagnosis of clinical ASD. Methods Demographic information was collected for all patients, which included age, sex, body mass index, smoking status, and Charleston Comorbidity Index (CCI). Several radiographic parameters were measured preoperatively, immediately postoperatively, and at the last follow-up: C2–C7 lordosis, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and T1 slope C2–C7 lordosis were measured using the Cobb angle between the inferior end plate of C2 to the inferior end plate of C7. Radiographic and clinical factors associated with ASD were analyzed postoperatively. Results Four patients (4.8%) presented with clinical evidence of ASD, all of whom also showed signs of radiographic ASD and improved with conservative measures. No patients underwent reoperation for ASD at the C7–T1 junction. Thirty patients (36.1%) presented radiographic evidence of ASD. These were generally older (54.4 vs. 48.4 years; p=.014). There were neither significant differences in radiographic parameters nor between single- versus multilevel ACDFs and the development of ASD. Conclusions The cervicothoracic junction may present with vulnerability to ASD given the junctional biomechanics. However, this study provides evidence that an ACDF with the caudal level of C7 does not incur additional risk of ASD, showing similar outcomes to ACDFs at other levels.

BACKGROUND CONTEXT Anterior cervical discectomy and fusion (ACDF) has been associated with successful outcomes for a variety of degenerative conditions of the cervical spine via neural decompression and stabilization. ACDF for one or two levels using allograft and rigid plating gives a high union rate with good clinical outcome. However, concerns regarding the potential stress-shielding associated with rigid plating, the lack of healing potential with allograft, pseudarthrosis, subsidence, loss of lordosis and reoperation have previously been discussed, particularly for multilevel cases. PURPOSE The purpose of the current study is to detail the radiographic and clinical outcomes of a series of three-level primary ACDF procedures using a rigid construction with cortico-cancellous allograft at a single institution. STUDY DESIGN/SETTING Retrospective cohort series. PATIENT SAMPLE A retrospective review was performed on 98 patients who underwent a primary three-level ACDF with rigid plating and cortico-cancellous allograft by a single-surgeon from 2008 to 2014 with a minimum of 1-year follow-up. Exclusion criteria included revision surgeries, infections, anterior or posterior surgeries, and follow-up of less than 12 months. OUTCOME MEASURES Demographics, perioperative data, and complications were recorded. Preoperative, 2-week postoperative, and final follow-up images were reviewed to evaluate cervical sagittal vertical axis (SVA), segmental height, fusion, cervical lordosis, and fusion. Patient reported outcomes were obtained in the form of Neck Disability Index (NDI) scores and Visual Analog Scales (VAS) scores for the neck and arm. METHODS Radiographic measurements from preoperative, immediate postoperative, and final follow-up were compared using Student's t-tests. Bivariate and multivariate analyses were used to identify risk factors for patient report and radiographic outcomes such as: reoperations, graft lucencies, loss of lordosis, loss of segmental height, and progressive cervical SVA. RESULTS Average follow-up was 24.7±13.2 months. Rates of asymptomatic radiographic lucencies and total reoperations were 18% (17 patients) and 4% (4 patients) respectively. Immediate improvements in cervical lordosis (5.5°, p CONCLUSIONS Three-level ACDF with rigid-plating and cortico-cancellous allograft is an effective procedure for degenerative diseases of the cervical spine without the application of additional adjuncts or combined anterior-posterior cervical surgeries. Significant improvements in cervical lordosis, segmental height, and segmental alignment can be achieved with little change in cervical SVA and a low rate of reoperations over short-term follow-up. Similarly, patient reported outcomes show significant improvements following these three-level ACDF procedures.

BACKGROUND CONTEXT The optimal method of addressing the positive sagittal imbalance often present in degenerative scoliosis (DS) is controversial. An important distinction is whether or not the etiology of the loss of lumbar lordosis (LL) and positive sagittal imbalance often seen on preoperative radiographs, is truly structural, or whether it is more positional in nature given that spinal stenosis is almost always present in DS patients who require surgery. This distinction directly affects the decision about whether or not, in addition to decompression, the entire curve needs to be addressed (regional or global fusion), or if a lesser local fusion of only the symptomatic levels can be performed with a satisfactory radiographic result. PURPOSE This study aims to determine (1) if the loss of LL often associated with DS is structural or rather largely due to positional factors secondary to spinal stenosis, and (2) if the entire DS curve or a lesser local fusion of only the neurologically symptomatic levels need to be addressed. STUDY DESIGN/SETTING Retrospective case series. PATIENT SAMPLE We obtained radiographic and clinical data on 114 consecutive patients. We included patients if they had loss of normal LL (positive sagittal imbalance) observed on preoperative radiographs and underwent a decompression and instrumented posterolateral inter-transverse process arthrodesis of only their neurologically symptomatic levels in the setting of DS. We excluded patients if they had undergone a previous fusion, concomitant osteotomy procedure, or any type of interbody arthrodesis, or had less than 6 months follow-up. Of the original 114 patients identified, 68 fulfilled the above criteria. OUTCOME MEASURES Pre- and postoperative radiographs were reviewed to measure lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. Postoperative radiographs were also measured against preoperative extension lumbar radiographs and lumbar magnetic resonance imaging (MRI) to compare changes in radiographic pelvic parameters. METHODS Three independent members of the research team performed all measurements. Inter-rater reliability was calculated using a Pearson coefficient test and a strong correlation was considered if R>0.8. The three sets of measurements were then averaged for final statistical analysis. Relationships were considered significant at p RESULTS Average follow-up was 22 months. In addition to decompression, instrumented fusion was most commonly performed from L4 to S1 (N=17), followed by L3-S1 (N=12). The average PI found preop and postop was 52° and 53°, respectively. The average PT found preop and postop was 24° and 27°, respectively. Preoperative LL had a mean Cobb angle of 32° (range 2°–60°). Preop MRIs and lumbar extension radiographs revealed an average LL of 42° (range 10°–66°) and 48° (range 20°–74°), respectively. Initial postop radiographs (average 3 weeks) revealed that LL was corrected to a mean of 44° (range 14°–68°, p CONCLUSIONS We were able to correct LL to within 10° of the PI in this cohort of symptomatic DS patients with decompression and local instrumented fusion of symptomatic levels only. Loss of LL in symptomatic DS patients has a large positional component likely due to stenosis. Preoperative MRI and extension radiographs can be used to predict achievable postoperative LL correction.