Incidence Of Adjacent Segment Degeneration Research Articles

Older literature review of increased risk of adjacent segment degeneration with instrumented lumbar fusions.

Background:Adjacent segment degeneration (ASD) following lumbar spine surgery occurs in up to 30% of cases, and descriptions of such changes are not new. Here, we review some of the older literature concerning the rate of ASD, typically more severe cephalad than caudad, and highly correlated with instrumented fusions. Therefore, for degenerative lumbar disease without frank instability, ASD would be markedly reduced by avoiding instrumented fusions.Methods:In a prior review, the newer literature regarding the frequency of ASD following lumbar instrumented fusions (e.g., transforaminal or posterior lumbar interbody fusions [TLIF/PLIF] fusions or occasionally, posterolateral fusions [PLFs]) was presented. Some studies cited an up to an 18.5% incidence of ASD following instrumented versus noninstrumented fusions/decompressions alone (5.6%). A review of the older literature similarly documents a higher rate of ASD following instrumented fusions performed for degenerative lumbar disease alone.Results:More frequent and more severe ASD follows instrumented lumbar fusions performed for degenerative lumbar disease without instability. Alternatively, this entity should be treated with decompressions alone or with noninstrumented fusions, without the addition of instrumentation.Conclusions:Too many studies assume that TLIF, PLIF, and even PLF instrumented fusions are the “gold standard of care” for dealing with degenerative disease of the lumbar spine without documented instability. It is time to correct that assumption, and reassess the older literature along with the new to confirm that decompression alone and noninstrumented fusion avoid significant morbidity and even potentially mortality attributed to unnecessary instrumentation.

Radiologic Findings and Risk Factors of Adjacent Segment Degeneration after Anterior Cervical Discectomy and Fusion : A Retrospective Matched Cohort Study with 3-Year Follow-Up Using MRI.

ObjectiveThe purpose of this study was to figure out the radiologic findings and risk factors related to adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF) using 3-year follow-up radiography, computed tomography (CT), and magnetic resonance image (MRI).MethodsA retrospective matched comparative study was performed for 64 patients who underwent single-level ACDF with a cage and plate. Radiologic parameters, including upper segment range of motion (USROM), lower segment range of motion (LSROM), upper segment disc height (UDH), and lower segment disc height (LDH), clinical outcomes assessed with neck and arm visual analogue scale (VAS), and risk factors were analyzed.ResultsPatients were categorized into the ASD (32 patients) and non-ASD (32 patients) group. The decrease of UDH was significantly greater in the ASD group at each follow-up visit. At 36 months postoperatively, the difference for USROM value from the preoperative one significantly increased in the ASD group than non-ASD group. Preoperative other segment degeneration was significantly associated with the increased incidence of ASD at 36 months. However, pain intensity for the neck and arm was not significantly different between groups at any post-operative follow-up visit.ConclusionThe main factor affecting ASD is preoperative other segment degeneration out of the adjacent segment. In addition, patients over the age of 50 are at higher risk of developing ASD. Although there was definite radiologic degeneration in the ASD group, no significant difference was observed between the ASD and non-ASD groups in terms of the incidence of symptomatic disease.

Relationship between developmental canal stenosis and surgical results of anterior decompression and fusion in patients with cervical spondylotic myelopathy.

BackgroundAnterior cervical decompression and fusion (ACDF) has long been the preferred treatment for cervical spondylotic myelopathy (CSM). However, few studies have focused on surgical results of CSM in patients with developmental canal stenosis (DCS). The purpose of this study was to investigate DCS as a comorbidity in patients with CSM and the correlation between surgical results and DCS.MethodsFrom January 1995 to December 2005, 122 patients treated with ACDF for CSM were enrolled in this retrospective study. Pavlov’s ratio was used to evaluate cervical spinal canal size, with a value of < 0.82 at least one level indicating DCS. Patients were divided into two groups: those with DCS preoperatively (DCS group, n = 50 [41.0 %]) and those without DCS (non-DCS group, n = 72). Clinical data and radiological parameters were compared between groups.ResultsThere were no significant differences in preoperative and 2-year follow-up Japanese Orthopedic Association scores between groups. Both groups achieved satisfactory fusion rates (DCS, 92.0 %; non-DCS, 93.0 %). Adjacent-segment degeneration (ASD) was detected in 66.0 % of patients in the DCS group and in 43.0 % of patients in the non-DCS group (p = 0.01). However, there was no significant difference in the incidence of ASD requiring surgery between groups (p = 0.20).DiscussionDCS is a common comorbidity in patients with CSM. The findings of this study have added knowledge on the correlation between DCS and ASD after anterior fusion surgery.ConclusionsDCS did not affect neurologic improvement postoperatively at short-term follow-up. Although DCS increased the incidence of ASD after anterior fusion, it did not predict ASD requiring surgery. Therefore, patients with DCS must receive close follow-up.

Restoration of Cervical Alignment is Associated with Improved Clinical Outcome after One- and Two-Level Anterior Cervical Discectomy and Fusion

Background Anterior cervical discectomy and fusion (ACDF) remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative care. However, the maintenance and restoration of cervical alignment as a predictive factor for outcome has not yet been fully evaluated. The purpose of this study was to evaluate the impact of maintaining or restoring cervical alignment on one and two level ACDF patients’ outcome. Methods Data were collected from 104 patients who underwent one and two level ACDF. Cervical alignment was measured preoperatively and at follow-up visits. The patients were classified into three groups based on the postoperative change of their cervical alignment. Neck pain, arm pain, and Neck Disability Index (NDI) scores were obtained preoperatively and at the latest follow-up visit. Incidences of adjacent segment degeneration (ASD) and reoperations because of ASD were recorded. Results There were 64 patients in the Maintained group, 17 patients in the Restored group and 23 patients in the Kyphotic group. Pre-operatively, the neck pain scores, arm pain scores and NDI scores were not statistically different among the three groups (p>0.05). On average at 12 months follow-up, the neck pain scores improved by 2.7, 4.2, and 2.7 points respectively in the three groups (p>0.05). The patients’ arm pain scores improved by 2.1, 2.4, and 2.8 points respectively (p>0.05). NDI scores improved by 12, 31 and 13.7 points respectively (p 0.05). Conclusions The patients with restored cervical alignment had significantly greater NDI improvement and relatively better neck pain improvement. There was a trend for patients who had unchanged cervical kyphosis to have a higher incidence of ASD. Our study suggests that restoration of cervical alignment will contribute to improved clinical outcome in the patients who have one and two level ACDF surgeries. Level of Evidence This is a level III study.

Radiological Signs of Adjacent Segment Degeneration Patients with Cervical Spondylotic Radiculopathy Treated with Posterior Cervical Cages: Two-Year Follow-Up

BACKGROUND CONTEXT: Select patients with nerve compression and cervical radiculopathy secondary to spondylosis can be successfully treated with indirect posterior cervical decompression and fusion with posterior cervical cages. Cervical fusion may have an influence on adjacent segment degeneration (ASD). PURPOSE: The aim of this study was to assess radiological signs of ASD at 2 years follow-up in patients treated with posterior cervical cages for cervical spondylotic radiculopathy. STUDY DESIGN/SETTING: Retrospective evaluation of cervical radiographs. PATIENT SAMPLE: Fifty-three patients who underwent posterior cervical fusion with DTRAX cervical cages for cervical spondylotic radiculopathy were enrolled into the study. The lateral cervical X-ray images were taken in neutral position preoperatively and at 1 and 2 years postoperatively. OUTCOME MEASURES: The adjacent levels were evaluation consisted of measurements of:1) Proximal junctional kyphosis (PJK);2) Disc height ratio (DHR) – ratio of the disc height and the lower vertebrae height measured in the in the middle;3) Heterotopic ossification (HO) – none,!50%, O50 % , complete bridging of the disc;4) Kellgren and Lawrence Osteoarthritis Severity Grade (OSG).5) Neck Disability Index(NDI), Visual Analog Scale(VAS), and SF-12 Mental(MCS) and Physical Component Score(PCS). METHODS: The results were compared with ANOVA test, with p!0.05 considered as significant. ASD was defined as an increase of HO or OSG by 1 grade in new cases and by 2 grades if pre-existing disc degeneration was present before surgery (DDS). RESULTS: There were no revision surgeries at the operated level or at adjacent levels. Disc degeneration signs were present before surgery (DDS) in 21 patients in upper level and in 22 patients in lower level. In 2 patients there were new grade 1 ASD changes, 1 in level above and 1 in level below at 2 years postoperatively. In patients with pre-existing disc degeneration at the adjacent level, there were 0 cases of adjacent level degeneration progression of 2 grade or more. There were no significant changes in DHR and in PJK in all patients and in patients with ASD, however, there were tendency in patients with signs of ASD to decrease DHR in time. The mean PJK before surgery was -1.02 64.6 , 1 year after surgery -0.86 64.7 and 2 years after surgery was -0.59 65.4 ; p50.5342The mean DHR in all patients before surgery was 43.3 66.3 , 1 year after surgery 43.3 66.6 and 2 years after surgery was 43.1 66.8 ; p50.7290The mean DHR in ASD patients before surgery was 44.1 65.6 , 1 year after surgery 42.667.2 and 2 years after surgery was 40.9 67.8 ; p50.1836.The mean preop and 2-year scores were: NDI: 32.3 vs 9.1 (p!0.0001); VAS Neck Pain: 7.4 vs 2.6(p!0.0001); VAS Arm Pain: 7.4 vs 2.6 (p!0.0001); SF-12 PCS: 34.6 vs 43.6(p!0.0001) and SF-12 MCS: 40.8 vs 51.4 (p!0.0001). CONCLUSIONS: Indirect decompression and posterior cervical fusion using the DTRAX Cage may be an effective option in select patients with single level cervical radiculopathy. In patients treated with posterior cervical cage progression of disc degeneration is much more common on the basis of preoperative changes than new ASD. Posterior cervical fusion with cervical cage does not induce or accelerate adjacent segment degeneration in the great majority of patients (more than 1 score). Further evaluation to establish long-term incidence of ASD in patients treated with posterior cervical cage is needed. FDA DEVICE/DRUG STATUS: DTRAX Cervical Cage (Providence Medical Technology, Inc.) (Approved for this indication).

Adjacent Segment Disease After Posterior Lumbar Interbody Fusion: Based on Cases With a Minimum of 10 Years of Follow-up.

Retrospective case-controlled study. To investigate the incidence of adjacent segment degeneration (ASD) and the associated risk factors during a period of at least 10 years after posterior lumbar interbody fusion (PLIF). ASD is a problematic sequelae after spinal fusion surgery. Few long-term follow-up studies have investigated ASD after PLIF; thus, magnetic resonance imaging (MRI) data available for the evaluation of postoperative changes associated with ASD are limited. One hundred one patients were retrospectively enrolled. The minimum follow-up was 10 years after surgery. Preoperative and postoperative (2, 5, and 10 yr after surgery) Radiographs and MRI images were evaluated. Disc height, vertebral slip, and intervertebral angle were examined on radiographical images. Disc degeneration and spinal stenosis on MRI images were evaluated. Risk factors for developing early-onset radiographical ASD were evaluated using a multivariate logistic regression analysis. The degenerative changes in disc height, vertebral slip, and intervertebral angle on radiographs 10 years after surgery were found in 12, 36, and 17 cases, respectively, at the cranial-adjacent level and in 3, 6, and 11 cases, respectively, at the caudal-adjacent level. Increased disc degeneration and spinal stenosis worsening were observed in 62 and 68 cases, respectively, at the cranial-adjacent level and in 25 and 12 cases, respectively, at the caudal-adjacent level on MRI 10 years after surgery. Ten patients (9.9%) required reoperation, and 80% of revision surgeries were performed more than 5 years after the initial surgery. High pelvic incidence was a risk factor for developing early-onset radiographical ASD. The majority of the reoperations for ASD were performed more than 5 years after the initial lumbar fusion surgery, although the progression of radiographical ASD began in the early postoperative period. A high degree of pelvic incidence was a risk factor for developing early-onset radiographical ASD. Obtaining appropriate lumbar lordosis in PLIF is important for preventing ASD. 4.

X-Ray-based Kinematic Analysis of Cervical Spine According to Prosthesis Designs

A retrospective study. To identify significant kinematic changes in the cervical spine after cervical artificial disk replacement (ADR) using prostheses with diverse designs. Various types of artificial disks are used for cervical ADR. However, few clinical studies with a follow-up of 2 or more years have reported on the change in the curvatures and range of motion (ROM) of the cervical spine after cervical ADR in relation to different designs. The cohort comprised 58 patients who underwent single-level cervical ADR for radiculopathy. The patients were divided into 4 groups according to the device they received: Mobi-C, Bryan, PCM, and Prestige LP. The radiographs of the cervical spine were obtained preoperatively and at 12, 24, and 36 months after surgery. Several kinematic parameters, including lordotic angles and ROM of the cervical spine, index level, and superior and inferior adjacent disk levels, were assessed preoperatively and at predefined follow-up time points. Cervical sagittal lordosis in patients who received Bryan and PCM prostheses increased at the last follow-up period. The 4 patient groups showed a trend toward an increase of lordosis in the superior adjacent segment with time. The patients who received the Bryan device lost their preoperative lordotic angle at the inferior adjacent level. The ROM of the cervical spine in patients who received Bryan and PCM prostheses increased at the last follow-up compared with preoperative values. The incidence of adjacent segment degeneration in the Mobi-C, Bryan, Prestige LP, and PCM groups were 14.2%, 25%, 9.0%, and 7.6%, respectively. These results suggest preservation of sagittal ROM and increased superior adjacent segment kinematics, regardless of prosthesis design. Devices with an unconstrained design may not be beneficial to adjacent segment kinematics compared with semiconstrained prostheses.

Adjacent Segment Degeneration after Posterior Lumbar Interbody Fusion: Based on Cases with a Minimum of 10 years of Follow-Up

Introduction Adjacent segment degeneration (ASD) is problematic sequelae after spinal fusion surgery. ASD is observed in 36 to 84% of patients followed-up for 5 years after lumbar fusion surgery. However, there are few reports of long-term follow-up studies after PLIF, although 75% of cases requiring reoperation for ASD were discovered &gt; 4 years after the initial surgery. Moreover, there are limited reports describing changes related to disc degeneration and spinal stenosis on magnetic resonance imaging (MRI) after PLIF. The purpose of this study is to investigate the incidence of ASD and the associated risk factors over at least 10 years after PLIF. Material and Methods This study was a retrospective case-controlled study. A total of 167 patients who underwent PLIF were enrolled at a single spine center from April 1996 to May 2003. The inclusion criteria included age (&gt; 21 years at the time of surgery), magnitude of scoliosis (Cobb angle &lt; 15 degrees), and no additional decompression surgery at the level adjacent to the PLIF area. Overall, 66 patients were excluded in addition to those who did not meet these criteria, because they had not been followed up for at least 10 years. Finally, 101 patients (41 males, 60 females) with a mean age of 56.4 ± 15.3 years (range: 23–79 years) were included. The mean duration of follow-up was 11.6 ± 2.2 years (range: 10–17 years). Seventy patients had degenerative spondylolisthesis, 15 had spondylolytic spondylolisthesis, 11 had lumbar disc herniation, and 5 had spinal canal stenosis. Posterior lumbar interbody fusion was performed using pedicle screws, two carbon cages, and autologous iliac-crest bone graft. Preoperative and postoperative (2, 5, and 10 years after surgery) X-ray and MRI images were evaluated. Disc height, vertebral slip, and intervertebral angle were examined on X-ray images. Disc degeneration and spinal stenosis on MRI images were evaluated. Patients who developed severe spinal canal stenosis or exhibited listhesis (&gt; 3 mm) within 5 years after surgery were defined as having early-onset radiographic ASD. Risk factors for developing early-onset radiographic ASD were evaluated using a multivariate logistic regression analysis. Results The degenerative changes in disc height, vertebral slip, and intervertebral angle on X-ray 10 years after surgery were 12, 35, and 17%, respectively, at the cranial-adjacent level and 4, 7, and 13%, respectively, at the caudal-adjacent level. The incidences of disc degeneration and spinal stenosis were 61 and 29%, respectively, at the cranial-adjacent level and 67 and 14%, respectively, at the caudal-adjacent level on MRI 10 years after surgery. Ten patients (9.9%) required reoperation, and 80% of revision surgeries were performed &gt; 5 years after the initial surgery. High pelvic incidence was a risk factor for developing early-onset radiographic ASD. Conclusion The majority of the reoperation for ASD was performed &gt; 5 years after the initial lumbar fusion surgery, although the progression of radiographic ASD began in the early postoperative period. A high pelvic incidence was a risk factor for developing early-onset radiographic ASD. Obtaining appropriate lumbar lordosis in PLIF is important for preventing ASD.

Cervical canal stenosis and adjacent segment degeneration after anterior cervical arthrodesis.

Adjacent segment degeneration (ASD) is known to occur after anterior cervical arthrodesis. However, it is not known whether cervical canal stenosis enhances the risk of ASD. The purpose of this study was to explore whether congenital stenosis could be used as a predictor of ASD after anterior cervical decompression and fusion (ACDF). We enrolled 141 patients who had undergone ACDF for cervical myelopathy and/or radiculopathy, and had at least 6 years of follow-up. In standard radiographs of cervical spine in lateral view, bony congenital stenosis was evaluated and all patients were divided into two groups: stenosis (n = 63) and non-stenosis (n = 78). Radiographic ASD was assessed according to the criteria of Kellgren and Lawrence and correlated with symptomatic ASD. Clinical and radiological parameters were compared between the groups. The primary outcome was the rate of radiographic ASD after initial ACDF. The incidence of symptomatic ASD was assessed by Kaplan-Meier method. Radiographic ASD and symptomatic ASD developed in 46.8 % and 18.4 % of all patients, respectively. There was a significant association between congenital stenosis and radiographic ASD. The area under the receiver operating characteristic curve of preoperative anteroposterior (AP) diameter of cervical canal for predicting radiographic ASD was 0.756. 13.0 mm was the cutoff value of preoperative AP diameter of cervical canal predicting radiographic ASD. Kaplan-Meier analysis predicted a disease-free survival rate of symptomatic ASD in 97.2 % of patients at 5 years and 78.0 % at 10 years after ACDF. There was no significant difference in survival rates of the adjacent segment between the two groups via log-rank analysis (P = 0.102). Congenital stenosis can increase the rate of radiographic ASD after initial ACDF. The cutoff value of 13.0 mm for preoperative AP diameter of cervical canal had the highest validity for predicting radiographic ASD.

Longer plate-to-disc distance prevents adjacent-level ossification development but does not influence adjacent-segment degeneration.

Retrospective case-control study. To clarify the association between plate-to-disc distance (PDD) and adjacent-level ossification development (ALOD) and adjacent segment degeneration (ASD). Anterior cervical discectomy and fusion with plating provides higher fusion rate and improved alignment but has been reported to result in ALOD and ASD. We retrospectively reviewed 218 patients with solid fusion after anterior cervical arthrodesis with plating at our institution between January 2004 and December 2010. PDD was measured on postoperative lateral radiographs for each adjacent disc space and used to assign patients to 1 of 3 groups: group L, long PDD (>5 mm); group S, short PDD (0 mm ≤PDD ≤5 mm); and group N, PDD (<0 mm, disk space encroachment). Mean follow-up was 5.3 years. Incidences of cranial and caudal ALOD and ASD with and without symptoms were compared among groups. Severity of caudal ossification was not measured in 30 patients because bony overlap precluded adequate visualization of the caudal level. Ossification developed in 134 (61%) of 218 cranial adjacent disc spaces and 45 (24%) of 188 caudal adjacent disc spaces (P < 0.01). Mean cranial PDD was shorter than mean caudal PDD (P < 0.01). Ossification rate was higher in group N than in group S at the cranial adjacent disc spaces (100% vs. 66%, P < 0.01). Incidences of both cranial and caudal ALOD were significantly higher in group S than in group L (66% vs. 31%, P < 0.01; and 31% vs. 13%, P < 0.01, respectively). No significant differences in symptomatic and asymptomatic ASD were seen among groups. Longer PDD does not decrease the incidence of ASD but it can prevent ALOD. We now attempt to place anterior cervical plates of 5 mm or greater from adjacent disc spaces. 3.

Restoration of Cervical Alignment is Associated with Improved Clinical Outcome after One and Two Level Anterior Cervical Discectomy and Fusion.

Anterior cervical discectomy and fusion (ACDF) remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative care. However, the maintenance and restoration of cervical alignment as a predictive factor for outcome has not yet been fully evaluated. The purpose of this study was to evaluate the impact of maintaining or restoring cervical alignment on one and two level ACDF patients' outcome. Data were collected from 104 patients who underwent one and two level ACDF. Cervical alignment was measured preoperatively and at follow-up visits. The patients were classified into three groups based on the postoperative change of their cervical alignment. Neck pain, arm pain, and Neck Disability Index (NDI) scores were obtained preoperatively and at the latest follow-up visit. Incidences of adjacent segment degeneration (ASD) and reoperations because of ASD were recorded. There were 64 patients in the Maintained group, 17 patients in the Restored group and 23 patients in the Kyphotic group. Pre-operatively, the neck pain scores, arm pain scores and NDI scores were not statistically different among the three groups (p>0.05). On average at 12 months follow-up, the neck pain scores improved by 2.7, 4.2, and 2.7 points respectively in the three groups (p>0.05). The patients' arm pain scores improved by 2.1, 2.4, and 2.8 points respectively (p>0.05). NDI scores improved by 12, 31 and 13.7 points respectively (p<0.05). The incidences of ASD and reoperations because of ASD were 16%, 12% and 35% respectively (p>0.05). The patients with restored cervical alignment had significantly greater NDI improvement and relatively better neck pain improvement. There was a trend for patients who had unchanged cervical kyphosis to have a higher incidence of ASD. Our study suggests that restoration of cervical alignment will contribute to improved clinical outcome in the patients who have one and two level ACDF surgeries. This is a level III study.

Adjacent segment degeneration after single-level anterior cervical decompression and fusion: Disc space distraction and its impact on clinical outcomes

The purpose of this study was to find whether excessive distraction of the disc space for cage insertion was a risk factor for adjacent segment degeneration (ASD) after anterior cervical decompression and fusion (ACDF). One hundred and sixteen consecutive patients who underwent ACDF for single-level cervical disc herniation between June 2006 and November 2008 were retrospectively reviewed. Preoperative, postoperative and final follow-up disc height (DH), sagittal segmental alignment (SSA), and sagittal alignment of the cervical spine (SACS) were measured and compared between the ASD group and non-ASD group. In 116 patients, ASD was radiographically proven in 28 (24.1%) patients. The clinical outcomes were significantly improved compared to the preoperative scores in both groups. However, the postoperative and final follow-up DH of the ASD group were significantly higher than in the non-ASD group (p<0.05). In addition, the postoperative DH was significantly correlated with the postoperative or final follow-up SSA (p<0.05). However, postoperative DH was not found to significantly correlate with postoperative or final follow-up SACS (p=0.072 and p=0.096, respectively). Multivariate analysis showed that postoperative DH was the most significant risk factor for ASD. The clinical outcomes of ACDF for single-level degenerative cervical disc disease were satisfactory. Postoperative DH (the distracted distance) had the greatest impact on the incidence of ASD. Excessive disc space distraction is a considerable risk factor for the development of radiographic ASD.

Incidence of adjacent segment degeneration in cervical disc arthroplasty versus anterior cervical decompression and fusion meta-analysis of prospective studies.

PurposeTo evaluate the incidence of adjacent segment disease (ASD) requiring surgical intervention between anterior cervical decompression and fusion (ACDF) and total disc replacement (TDR).BackgroundThe concern for ASD has led to the development of motion-preserving technologies such as TDR. However, whether replacement arthroplasty in the spine achieves its primary patient-centered objective of lowering the frequency of adjacent segment degeneration is not verified yet.MethodsA comprehensive literature search was performed using PubMed, Cochrane Central Register of Controlled Trials and Embase. These databases were thoroughly searched for prospective randomized studies comparing ACDF and TDR. Eight studies met the inclusion criteria for a meta-analysis and were used to report an overall rate of ASD for both ACDF and TDR.ResultsPooling data from 8 prospective studies, the overall sample size at baseline was 1,726 patients (889 in the TDR group and 837 in the ACDF group). The ACDF group had significantly more ASDs compared with the TDR group at 24 months postoperatively [odds ratios (OR), 1.31; 95 % confidence interval (CI), 1.04–1.64; p = 0.02]. The TDR group had significantly fewer adjacent segment reoperations compared with the ACDF group at 24 months postoperatively (OR, 0.49; 95 % CI, 0.25–0.96; p = 0.04).ConclusionsFor patients with one-level cervical degenerative disc disease (CDDD), total disc replacement was found to have significantly fewer ASDs and reoperations compared with the ACDF. Cervical replacement arthroplasty may be superior to ACDF in ASD. Therefore, cervical arthroplasty is a safe and effective surgical procedure for treating CDDD. We suggest adopting TDR on a large scale.

Clinical and radiological results of two hybrid reconstructive techniques in noncontiguous 3-level cervical spondylosis

To date, formulation of the optimal surgical protocol for noncontiguous multilevel cervical spondylosis remains controversial, and the corresponding clinical data continue to be limited. The purpose of this study was to compare the clinical and radiological outcomes of two hybrid reconstructive techniques in noncontiguous 3-level cervical spondylosis (2 contiguous disc levels and 1 "skip" disc level [nonoperated level between 2 operated levels]). The incidence of adjacent-segment degeneration (ASD) was also evaluated. Sixty-three consecutive patients with noncontiguous 3-level cervical spondylosis who underwent two different hybrid methods of treatment were retrospectively reviewed. The patients were divided into 2 groups, the fusion group and the arthroplasty group. A titanium mesh cage and an anterior cervical plate were used after the anterior cervical corpectomy, and then a stand-alone cage (the fusion group) or an artificial cervical disc (the arthroplasty group) was used after the discectomy. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scale score and the JOA scale score improvement rate preoperatively and during follow-up. Radiological results were assessed using global angle and global range of motion (ROM) of the cervical spine. The ASD was also evaluated. The JOA scores of the patients significantly improved postoperatively and were well maintained within the follow-up period, as did the JOA scale score improvement rate. The mean global angle of the cervical spine of the patients significantly increased postoperatively. At the last follow-up evaluation, the mean global ROM was retained by patients in the arthroplasty group (p > 0.05) but not by patients in the fusion group (p = 0.00). There was no significant difference in the incidence of ASD between the 2 groups (p = 0.114). However, at the skip levels, patients in the fusion group had a higher incidence of ASD than patients in the arthroplasty group (p = 0.038). Both of the hybrid procedures (anterior cervical corpectomy and fusion [ACCF] + anterior cervical discectomy and fusion, and ACCF + cervical disc arthroplasty [CDA]) yielded favorable clinical and radiological outcomes in the treatment of noncontiguous 3-level cervical spondylosis. Moreover, the ACCF + CDA procedure may have the ability to decrease the likelihood of ASD in appropriate patients.

The difference in superior adjacent segment pathology after lumbar posterolateral fusion by using 2 different pedicle screw insertion techniques in 9-year minimum follow-up.

A prospective study was performed. To test the hypothesis that different pedicle screw insertion positions would increase the likelihood of superior adjacent segment degeneration (ASD). Lumbar fusion surgery is a widely accepted treatment of lumbar diseases, such as lumbar stenosis, trauma, tumor, and spondylolisthesis. Fusion and clinical success rates have increased because of improvements in instrumentation and bone graft material. In contrast, numerous complications and problems of fusion surgery have been reported, with ASD being one of the most important. This prospective study included 210 patients with low-grade isthmic spondylolisthesis. From January 1999 to December 2003, patients were randomized underwent posterolateral fusion using 2 different pedicle screw insertion positions. The patients were followed up postoperatively and were assessed with regard to radiological and clinical outcomes. Radiological outcomes were assessed mainly on the basis of disc degeneration, facet joint degeneration, and bone fusion. Clinical outcomes were evaluated mainly with the use of visual analogue scale for pain and the Oswestry Disability Index. A total of 178 of 210 (84.7%) patients were available for at least 9-year radiological and clinical follow-up data: 85.3% (87/102) patients in group A and 84.3% (91/108) patients in group B. Bone fusion was achieved in all patients at the last follow-up. ASD was proven in 110 (61.8%) of 178 patients. The incidences of radiographical and symptomatic ASD were 57.9% (103/178) and 3.9% (7/178), respectively. The incidence of ASD in group B was significantly lower than that in group A. Results of clinical outcomes showed lower visual analogue scale and Oswestry Disability Index scores in 2 groups than preoperative scores, but group B had greater improvement on the Oswestry Disability Index scores than group A in patients with ASD. The degeneration of superior adjacent segment is closely related to the position of the pedicle screws during lumbar fusion surgery. The position of the pedicle screw farther from the facet joint surface can reduce the degeneration of superior adjacent segment. 3.

Long-term result of posterolateral fusion of the lumbar spine using the Tadpole system.

BackgroundFailure of pedicle screw fixation is often seen in patients with severe osteoporosis. We developed new lumbar spinal instrumentation (Tadpole system) for elderly patients who have osteoporotic bone and poor general health status. The objective of this study was to document the long-term clinical outcomes after Tadpole system fixation, the rate of spinal fusion, the incidence of adjacent segment degeneration, the rate of instrumentation failure, and the overall complications.MethodsSixty patients who underwent posterolateral spinal fusion using the Tadpole system, in whom a radiograph of the lumbar spine was taken at more than 5 years after operation, were involved in this study. The improvement rate of the Japanese Orthopaedic Association (JOA) score, rate of spinal fusion, presence or absence of adjacent segment degeneration, rate of instrumentation failure, and postoperative complications of each patient were assessed at 5 years postoperatively.ResultsThe mean JOA score improvement was 72.5%, and the posterolateral spinal fusion rate was 93.3% (56 of 60 patients) at the last follow-up. Adjacent segment degeneration occurred in only two patients who showed decreased intervertebral disc height, and instrumentation failure (hook deviation) was observed in one patient. No other complications were observed in any patients.ConclusionTadpole system fixation shows favorable long-term clinical outcomes.

Disc Space Excessive Distraction is a Potent Risk Factor for Adjacent Segment Degeneration after Anterior Cervical Discectomy and Fusion

Introduction We reported that excessive disc space distraction caused by insertion of large cages during anterior cervical discectomy and fusion (ACDF) induces adjacent segment degeneration (ASD). Previous reports indicated that over distraction of disc space was an independent risk factor for ASD after posterior lumbar interbody fusion. We therefore hypothesize that the incidence of ASD after ACDF with larger size of cages should be higher than that ACDF with normal cages due to this loss of disc space distraction. Materials and Methods Radiographic ASD is defined as development of spondylolisthesis &gt;3 mm, decrease in disc height &gt;3 mm, or intervertebral angle at flexion lesser than −5 degrees. Symptomatic ASD is defined by a decrease of ≥ 4 points in Japanese Orthopedic Association score. A 130 patients with cervical spondylotic radiculopathy were treated with either ACDF with larger size of cages ( n = 45) or ACDF with normal cages ( n = 85) and followed up for a minimum of 2 years (mean, 39.2 months). Results Disc space distraction in the normal cage group was significantly smaller (0.4 mm) as compared with the larger size group (1.8 mm). The incidence of clinical ASD in the normal cage group (2%, 1/45) was also significantly less than that in the larger size group (15%, 13/85). Multivariate analysis showed that disc space distraction was the most significant risk factor. Conclusion Among various risk factors for ASD after ACDF, the excessive distraction of disc space proved to be a potent risk factor for ASD. Disclosure of Interest None declared

Adjacent Intervertebral Disc Changes in Patients with Isobar Semirigid Dynamic Stabilization System

Introduction The reported incidence of adjacent segment degeneration (ASD) after lumbar fusion ranges from 8 to &gt; 100%, average 27%. Another literature review reported that 5.2 to 18.5% of patients required surgery for adjacent segment disease after lumbar fusion surgery. Posterior dynamic stabilization systems may prevent the development and progression of ASD after surgery. Hybrid dynamic stabilization with posterior spinal fusion, or “Topping-off surgery,” is applied in patients with preoperative adjacent segment degeneration. The objective of this approach is to protect the degenerative adjacent segment from progressing. Efficacy of this procedure is debated. The objective of this study was to evaluate intervertebral disk changes of the dynamically stabilized spine segment in patients receiving single-level intervertebral fusion and adjacent segment dynamic stabilization using the Isobar (Alphatec Spine, Inc.) semirigid dynamic stabilization system. Materials and Methods Twenty-seven patients with confirmed degenerative disk disease were enrolled in a retrospective study. Patients received single level intervertebral fusion and dynamic stabilization of the adjacent level using the Isobar semi-rigid dynamic stabilization system. Patient outcomes were evaluated by visual analogue scale for pain (VAS) and Chinese version of Oswestry Disability Index (ODI). Intervertebral space ratio (IVS) and range of motion (ROM) were measured on plain radiographs. MRI relative gray-scale values of the central bright area of discs were analyzed by Image J software. Results Of the 27 patients, 16 were male and 11 were female. Ages ranged from 31 to 65 years (average 47 years). Average duration of surgery was 213 (SD = 52) minutes and average blood loss was 225 mL (SD = 105). The average follow-up time was 27 months, ranging from 24 to 40 months. There was no significant change in relative gray-scale value of adjacent disc between preoperative and two year follow-up (23.98 ± 8.86 and 22.22 ± 6.25, respectively, p = 0.46). Relative gray-scale values of first cephalic adjacent disc were reduced at 2 years follow-up compared with baseline (28.63 ± 8.35 and 32.54 ± 10.75, respectively, p = 0.06). Significant difference was found in relative gray-scale value of second cephalic adjacent disc between baseline and 2-year follow-up (35.51 ± 8.15 and 29.29 ± 7.56, respectively, p &lt; 0.01). The inter-vertebral space (IVS) of index level was maintained after the surgery (Table 1). There was no statistical difference between the IVS before the surgery and final follow-up ( p = 0.33). The range of motion (ROM) of the adjacent level was reduced from 6.91 ± 3.14 preoperatively to 2.46 ± 1.03 degrees at the final follow-up ( p &lt; 0.05). There were no significant differences in the index level ROM among any of the follow-up times. VAS and ODI scores significantly improved preoperatively to final follow-up (VAS: 6.12 ± 0.80 and 1.65 ± 0.69, respectively, p = &lt; 0.01; ODI: 54.91 ± 10.96 and 14.61 ± 3.88, respectively, p = &lt;0.01). One patient received a debridement due to wound infection after operation, but the fixation system and interbody cage were not removed. This patient recovered well after the debridement. At the 2-year follow-up, one patient had two screw fractures at S1 level and another patient had two screws loosen. Conclusion Dynamic stabilization of the level adjacent to the fused level using the Isobar TTL Semi-rigid Spinal System seems to prevent progression of degenerative changes in the stabilized spine segment and is associated with favorable patient outcomes. Disclosure of Interest Q. Zhou: Conflict with Third Military Medical University, AO International R. Shi: None declared B. Kopjar: Conflict with AO Foundation, Smith &amp; Nephew, Cerapedics H. Wang: None declared D. Chen: None declared H. Li: None declared N. Di: None declared F. Luo: None declared F. Dai: None declared J. Xu: None declared

Spinal motion and intradiscal pressure measurements before and after lumbar spine instrumentation with titanium or PEEK rods

Spinal instrumentation and fusion have been incriminated as contributing to adjacent segment degeneration (ASD). It has been suggested that ASD results from increased range of motion and intradiscal pressure (IDP) adjacent to instrumentation. Posterior dynamic stabilization with polyetheretherketone (PEEK) rods has been proposed as potentially advantageous compared to rigid instrumentation with titanium (Ti) rods in reducing the incidence of ASD. We evaluated segmental motions in the cadaveric spine instrumented with PEEK or Ti rods from L3 to S1, as well as the adjacent segment motions and IDP at L1–2 and L2–3. Human cadaveric spines were potted at T12–L1 and S1–2. Spinal instrumentation from L3–S1 was accomplished using pedicle screws with either PEEK or Ti rods. Specimens were subjected to displacement controlled testing: 15° flexion, 15° extension, 10° lateral bending, and 5° right axial rotation using the MTS machine (MTS, Minneapolis, MN, USA). Intradiscal pressure was measured by placing pressure transducers into the intervertebral disc at L1–2 and L2–3. Spinal motion of L2 relative to L3, and L3 relative to S1 was tracked using a three dimensional motion analysis system. Instrumentation with PEEK and Ti rods was associated with a decrease in L3–S1 motion compared to the intact state that was significant in flexion (p=0.002), and extension (p=0.0075). Instrumentation with PEEK and Ti rods was associated with an increase in IDP at L1–2 that was significant in flexion (p=0.0028). Instrumentation with either PEEK or Ti rods resulted in decreased motion at the instrumented levels while increasing IDP at the adjacent level.

Changes in the Adjacent Segment 10 Years After Anterior Lumbar Interbody Fusion for Low-Grade Isthmic Spondylolisthesis

Adjacent segment degeneration is a long-term complication of arthrodesis. However, the incidence of adjacent segment degeneration varies widely depending on the patient's age and underlying disease and the fusion techniques and diagnostic methods used. We determined (1) the frequency of adjacent segment degeneration and increased lordosis on imaging tests, (2) the frequency and severity of clinical sequelae of these findings, including revision surgery, and (3) the sequence of degeneration and risk factors for degeneration. Seventy-three patients underwent anterior lumbar interbody fusion for low-grade isthmic spondylolisthesis at one institution between October 2000 and February 2002. Forty-nine (67%) of the original patients had complete radiographic and clinical followup for 10 years. CT and MRI were performed at 5 years and 10 years in all cases. The disc height, sagittal profiles, and facet and disc degeneration at adjacent levels were examined to identify radiographic and clinical adjacent segment degeneration. Mean followup was 134.2 months (range, 120-148 months). Cranial segment lordosis increased (from 14.8° to 18.5°; p < 0.001), while caudal segment lordosis changed little (from 16.4° to 17.3°). Radiographic and clinical adjacent segment degeneration occurred in 19 (38.8%) and six (12.2%) patients, respectively, and two patients (4.1%) underwent revision surgery. Patients with adjacent segment degeneration had more advanced preexisting facet degeneration than patients without adjacent segment degeneration (odds ratio: 18.6; 95% CI, 1.97-175.54, p = 0.01). Acceleration of disc and facet degeneration occurred in 4.1% and 10.2%, respectively. Adjacent segment degeneration requiring surgery is rare, although radiographic adjacent segment degeneration is common after anterior lumbar interbody fusion for isthmic spondylolisthesis. The only risk factor we found was preexisting facet degeneration of the cranial segment. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.