Adjacent Level Disc Degeneration Research Articles

Minimally Invasive Fixation in Osteoporotic Vertebral Fractures: A Review Article

here are several surgical strategies which have been proposed to treat the osteoporotic patient with vertebral fracture, ranging from vertebral body cement augmentation, percutaneous/mini-open short segment pedicle screw fixation, and cortical bone trajectory screw to kyphotic deformity correction surgery. Minimally invasive spine surgery has the potential benefits of faster recovery, reduced blood loss, less postoperative wound pain, lower infection risk, and shorter length of hospital stay. Novel surgical techniques such as percutaneous instrumentation fixation, cortical bone trajectory technique, screw cement augmentation, and vertebral body augmentation are developed. However, various complications have been reported, including pedicle fracture, instrumentation loosening, adjacent-level disc degeneration with herniation, and progressive junctional kyphosis. The purpose of this review was to outline various advancements in minimally invasive spinal surgery for patients with osteoporosis. Minimally invasive surgical techniques for fixation including percutaneous instrumentation, cortical bone trajectory technique, screw cement augmentation, and vertebral body augmentation have benefited patient with osteoporosis. Studies and discussions about short-segment pedicle screw fixation (one level above and below the fracture level) have shown that it provides enough stability for thoracolumbar burst fractures. There are also complications, including cement embolism, adjacent vertebral fracture, neuraxial anesthesia, and infection, which have been observed with the above technique. With the advancement of instrument and technique, the complication rate decreased in recent studies. Minimally invasive fixation still has many advantages for patients with osteoporosis. Many of these studies and strategies only have evidence from biomechanical and cadaveric studies and require further clinical trials to establish their clinical efficacy.

Clinical and radiological mid- to long-term investigation of anterior lumbar stand-alone fusion: Incidence of reoperation and adjacent segment degeneration

IntroductionAnterior stand-alone fusion (ASAF) devices have been developed in an attempt to reduce adjacent segment degenerative changes observed with posterior instrumented fusion techniques.Research questionThe purpose of this study was to assess mid- to long-term clinical and radiological results following ASAF at the lumbosacral junction with special emphasis on the assessment of adjacent level pathologies.Materials & Methods: Clinical outcome scores and radiological data were acquired within an ongoing single-center prospective cohort study. Progression of adjacent level degeneration was evaluated based on MRI scans according to the Pfirrmann and Weishaupt classification system by two independent radiologists.ResultsThe results from 37 patients (FU ​≥ ​5 years) demonstrated high satisfaction rates and significant improvements in VAS and ODI scores. N ​= ​8 patients (21.6%) had to undergo subsequent surgery at the cranially adjacent level. The incidence of adjacent level disc degeneration and adjacent facet joint degeneration was 24.3% and 35.1%, respectively. More pronounced degenerative changes of the adjacent level discs (p ​= ​0.005) and facet joints (p ​= ​0.042) prior to surgery and a lower segmental lordosis reconstruction at the lumbosacral junction (p ​= ​0.0084) were identified as potential risk factors for the development of subsequent adjacent level pathologies.Discussion & ConclusionThe study revealed satisfactory clinical results at a mid-to long-term FU of ≥5 years. The incidence of adjacent level degeneration was higher than initially expected. Patients with preexisting radiographic signs of degenerative adjacent level changes have a higher risk for subsequent deterioration necessitating reoperation at the adjacent segment at later stages. Furthermore, adequate intraoperative segmental lordosis reconstruction at the index segment is paramount as the present data reveal this to be a key protective factor for adjacent segment preservation.

Radiological risk factors for recurrent lumbar disc herniation after percutaneous transforaminal endoscopic discectomy: a retrospective matched case-control study

To investigate radiological risk factors for recurrent lumbar disc herniation (rLDH) after percutaneous transforaminal endoscopic discectomy (PTED). Patients who underwent PTED due to a single-level L4-L5 or L5-S1 disc herniation from January 2013 to May 2019 were enrolled in this study. A matched case-control design was carried out in a single institution. Cases were defined as those who developed rLDH, and controls were matched from those patients without rLDH according to corresponding clinical characteristics. The radiological parameters were compared between two groups. The radiological risk factors for rLDH after PTED were identified by univariate and multivariate logistic regression analysis. A total of 2186 patients who underwent PTED at L4-L5 or L5-S1 level were enrolled in this study. Sixty-eight patients were diagnosed with rLDH, and 136 patients were selected from the remaining 2118 nonrecurrent patients as matched controls. Univariate analysis demonstrated that herniation type (P = 0.009), surgical-level disc degeneration (P < 0.001), adjacent-level disc degeneration (P = 0.017), disc height index (DHI) (P = 0.003), and sagittal range of motion (sROM) (P < 0.001) were significantly related to rLDH. Multiple logistic regression analysis showed that low grade of surgical-level disc degeneration (P < 0.001), senior grade of adjacent-level disc degeneration (P < 0.001), a high DHI (P = 0.012), and a large sROM (P < 0.001) were the radiological independent risk factors. This study showed that low grade of surgical-level disc degeneration, senior grade of adjacent-level disc degeneration, a high DHI, and a large sROM were the radiological independent risk factors for rLDH after PTED.

Treatment of Patients with Scoliosis Using a Unique Anterior Scoliosis Correction Technique

Treatment for adolescent idiopathic scoliosis (AIS) is dependent upon multiple factors, including curve type and magnitude, curve progression, skeletal maturity, and clinical trunk deformity. While fusion is effective at achieving curve correction, it is associated with disadvantages including prominent implants beneath the skin, back muscle scarring and atrophy, decreased spine range of motion, and decreased functional spinal mobility. Additional concerns include the potential for longer term development of premature adjacent level disc and facet joint degeneration above and below the fusion. Due to these issues with spinal fusion, surgeons have explored alternative surgical approaches to correct spinal deformity and halt curve progression using either growth modulation or remodeling of the spine while preserving motion. This paper provides an overview of a non-fusion scoliosis correction technique called Anterior Scoliosis Correction (ASC).

Comparison of adverse events between cervical disc arthroplasty and anterior cervical discectomy and fusion: a 10-year follow-up

Cervical disc arthroplasty (CDA) has been advocated as an alternative to anterior cervical discectomy and fusion (ACDF) with the added potential to reduce the risk of adjacent level disc degeneration and segmental instability. However, the long-term adverse events of arthroplasty have yet to be fully reported. To investigate the 10-year follow-up adverse events rates between CDA and ACDF. The study was a randomized, prospective, multicenter Investigational Device Exemption (IDE) trial and its continued follow-up as a postapproval study (PAS). Single level surgeries were performed for cervical disc pathologies between May 2002 and October 2004. n=463 patients. Adverse events comparison of CDA and ACDF from self-reported and physiologic measures. At each evaluation time point, subjects were queried for adverse events since their last visit; and all adverse events were documented, regardless of whether or not they appeared related to the surgery or device. Adverse events were recorded, categorized, and assessed for severity and relationship to the study device and/or surgical procedure. The 10-year cumulative rates for each type of adverse events were summarized using a life-table method for the time-to-event analysis. A log-rank test was used to compare the two treatment groups. A total of 242 patients received CDA and 221 patients received ACDF. At 10-year follow-up, 54% (130/242) of CDA patients and 47% (104/221) of the ACDF subjects were evaluated. At up to 10-year follow-up, 231 patients in the CDA group (cumulative rate 98.4%) and 199 patients in the ACDF group (cumulative rate 98.7%) had at least one adverse event. Overall, the difference in the cumulative rate of all adverse events over 10 years was not statistically different (p=0.166). The cumulative rates of the following adverse events were not different between the two groups for cancer, cardiovascular, death, dysphonia/dysphagia, gastrointestinal, infection, urogenital, respiratory, implant displacement/loosening, implant malposition, neck and arm pain, neurological, other pain, spinal events, and intraoperative vascular injury. However, there were more adverse events in the CDA group resulting from trauma (p=.012) and more spinal events at the index level (p=.006). The ACDF group had significantly more nonunion events (p=.019), and nonunion outcome pending (p=.034), adjacent level spinal events (p=.033), and events that fell into the "other" category (p=.015). The cumulative rates of patients who had any adverse events were not different between the artificial cervical disc and the anterior cervical arthrodesis groups. In addition, the cumulative rates were not different between the two groups for the majority of categories as well.

Patterns of Cervical Disc Degeneration: Analysis of Magnetic Resonance Imaging of Over 1000 Symptomatic Subjects.

Study Design:Cross-sectional study.Objectives:The aim of this study was to evaluate cervical disc degeneration on magnetic resonance imaging (MRI) in a large population of symptomatic patients and to provide baseline data on the pattern of degeneration in order to understand how the cervical spine ages.Methods:We performed a cross-sectional study of 1059 patients who underwent upright cervical MRI for neck pain with and without neurological symptoms. A total of 6354 cervical discs from C2/3 to C7/T1 were evaluated. Cervical disc degeneration was evaluated on T2-weighted MRI and graded into 4 categories (Grades 0-III). Positive degeneration was defined as greater than Grade II. The correlation between age and total grade of degeneration of each patient was evaluated, as well as the prevalence and pattern of degeneration.Results:The average number of degenerated disc levels and the total grade of cervical disc degeneration significantly increase with age. In the patient group with 1-level degeneration, C5/6 was the most common degenerated level followed by C4/5 and C6/7. In the group with 2-level degeneration, C5/6 & C6/7 was most common followed by C4/5 & C5/6 and C3/4 & C4/5. Skip level degeneration was significantly rarer than contiguous level degeneration, and C7/T1 and C2/3 were the most unlikely to degenerate in multilevel degeneration.Conclusion:Disc degeneration is most common in the middle cervical spine (C5/6) and progresses to contiguous levels, except for C7/T1 and C2/3. This pattern may play a role in adjacent-level disc degeneration associated with spinal fusion.

Effect of intervertebral disc height on the range of motion and clinical outcomes after single-level implantation of Prestige LP cervical disc prosthesis

Cervical total disc replacement (TDR) is an emerging technology. Cervical arthroplasty theoretically reduces the risk of adjacent level disc degeneration and segmental instability. However, the factors that influence postoperative range of motion (ROM) and clinical outcomes are not fully understood. The aim of our study was to evaluate the effect of intervertebral disc height on the range of motion and clinical outcomes after single-level implantation of Prestige LP cervical disc prosthesis A total of 160 patients with single-level Prestige LP cervical disc prosthesis were evaluated. Preoperative and postoperative disc height and ROM were measured from lateral and flexion-extension radiographs by the CANVAS, and the clinical outcomes were evaluated by Japanese Orthopaedic Association (JOA) and Neck Disability Index (NDI). Patients with less than 4mm of preoperative disc height had a mean 1.4° increase in flexion-extension ROM after cervical arthroplasty, whereas patients with greater than 4mm of preoperative disc height had no change in flexion-extension ROM. Patients with a 6-8mm of postoperative disc height had significantly higher postoperative flexion-extension ROM (11.0°±2.9) than those with less than 6mm of postoperative disc height (8.7°±3.1, p=0.01). Patients with greater than 8mm of postoperative disc height have significantly lower postoperative flexion-extension ROM (mean, 8.9°±3.2) than those with 6-8mm of postoperative disc height (p=0.03). No significant difference was found between patients with <6mm of postoperative disc height and patients with >8mm of postoperative disc height (p=0.12). The postoperative JOA and NDI both have significant difference compared with preoperation(p<0.05). No correlation could be found between disc height and the postoperative ROM, JOA or NDI. Patients with less than 4mm of preoperative intervertebral disc height have a larger ROM after cervical arthroplasty. A 6-8mm of postoperative intervertebral disc height is the optimum range to maximize ROM. However, the optimal range did not translate into better clinical outcomes.

An Updated Meta-Analysis Comparing Artificial Cervical Disc Arthroplasty (CDA) Versus Anterior Cervical Discectomy and Fusion (ACDF) for the Treatment of Cervical Degenerative Disc Disease (CDDD).

A meta-analysis of published randomized controlled Trials (RCTs). The aim of this study was to compare the efficacy and safety of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) for the treatment of one-level cervical degenerative disc disease (CDDD). ACDF has been widely performed for the treatment of CDDD. However, the loss of motion at the operated level has been hypothesized to accelerated adjacent-level disc degeneration. CDA is designed to avoid the side effect of fusion. However, it is still uncertain whether CDA is more effective and safer than ACDF. We performed a meta-analysis of published RCTs to examine whether there was a superior clinical effects of CDA than ACDF. A PubMed database search through October 2014 was performed for relevant studies. We included RCTs that reported relevant data in the treatment of one-level CDDD, which were suitable for detailed extraction of data. We identified 18 RCTs eligible for analysis. The results of the meta-analysis indicated longer operative times, more blood loss, lower neck and arm pain scores reported on a visual analog scale (VAS), better neurological success, greater motion at the operated level, fewer secondary surgical procedures in the CDA group than in the ACDF group (P < 0.05). The 2 groups had similar lengths of hospital stay, Neck Disability Index scores, and rates of adverse events (P > 0.05). Findings of the present meta-analysis indicated that CDA was an effective and safe surgical procedure for the treatment of one-level CDDD, and CDA was found to be more superior than ACDF in terms of VAS neck and arm pain, neurological success, range of motion at the operated level, and secondary surgical procedures. 1.

The influence of adjacent level disc disease on discectomy outcomes.

The state of adjacent level discs and its impact on surgical outcomes following single-level lumbar discectomy have not been previously investigated. The purpose of the present study was to determine if a significant relationship exists between the degree of preoperative adjacent level disc degeneration and post-operative clinical outcomes following lumbar discectomy. This study retrospectively used preoperative magnetic resonance imaging (MRI) and prospectively collected data from a randomized clinical trial at two tertiary-care academic hospitals. Patients who underwent a primary, single-level lumbar discectomy were included. Exclusion criteria included prior lumbar surgery. Outcome measures were the Modified Oswestry Disability Index (ODI) score and Visual Analog Scale (VAS) scores for back and leg pain. These were recorded at baseline and at 3 months, 1, and 2 years postoperatively. An independent reviewer graded adjacent level disc degeneration on all preoperative MRIs using the Pfirrmann grading scale. These data were then analyzed for correlation with each outcome measure. Forty-seven patients were included in the study. No statistically significant correlations were found when comparing preoperative 3-month or 1-year postoperative scores or change from baseline of any outcome measure between Pfirrmann grades. Only about half the patients had 2-year follow-up, but at that time point a statistically significant difference in back VAS scores was observed between Pfirrmann groups. No other significant differences were observed at that point. The degree of preoperative adjacent level degeneration does not significantly affect functional or pain relief outcomes following lumbar discectomy up to 1 year after surgery.

Minimum 4-year outcomes of cervical total disc arthroplasty versus fusion: a meta-analysis based on prospective randomized controlled trials.

The prevalence of cervical disc disease is high, and the traditional surgical method of anterior cervical discectomy and fusion (ACDF) carries with it the disadvantages of motion loss at the operated level, and accelerated adjacent level disc degeneration. Preliminary results of the efficacy and reoperative rate comparing TDA versus ACDF have been reported; however, the long-term outcomes of TDA versus ACDF still remain a topic of debate.This review was prepared following the standard procedures set forth by the Cochrane Collaboration organization, and preferred reporting items for systematic reviews and meta-analyses (PRISMA). The only studies included were randomized controlled trials with a minimum of 4 years of follow-up data. The meta-analysis included the neck disability index (NDI), visual analog scale (VAS) of neck and arm pain, SF-36 physical component scores (SF-36 PCS), over success, neurological success, work status, implant-related complications, and secondary surgery events.Four randomized controlled trials meet the inclusion criteria. The long-term improvement of NDI, VAS of neck and arm pain, SF-36 PCS, over success, and neurological success favored the TDA group. The TDA group also had a lower incidence of secondary surgery for both the index level (RR: 0.45 [0.28, 0.72]) and adjacent level (RR: 0.53 [0.33, 0.88]).In this meta-analysis of 4 included RCTs with a minimum 4 years of follow-ups, total disc arthroplasty showed improvements over ACDF as measured by the NDI, VAS of neck and arm pain, and SF-36 PCS.

Long-term kinematic analysis of cervical spine after single-level implantation of Bryan cervical disc prosthesis: a review

COMMENTARY ON Ryu WHA, Kowalczyk I, Duggal N. Long-term kinematic analysis of cervical spine after single-level implantation of Bryan cervical disc prosthesis. Spine J 2013; 13:628–34 (in this issue). Ryu WHA, Kowalczyk I, Duggal N. Long-term kinematic analysis of cervical spine after single-level implantation of Bryan cervical disc prosthesis. Spine J 2013; 13:628–34 (in this issue). Long-term kinematic analysis of cervical spine after single-level implantation of Bryan cervical disc prosthesisThe Spine JournalVol. 13Issue 6PreviewCervical arthroplasty theoretically reduces the risk of adjacent level disc degeneration and segmental instability that may be seen after a cervical fusion. An essential argument in confirming the utility of cervical arthroplasty is long-term confirmation that cervical disc replacements can maintain physiological kinematics at the index and adjacent levels. Full-Text PDF

Long-term kinematic analysis of cervical spine after single-level implantation of Bryan cervical disc prosthesis

Cervical arthroplasty theoretically reduces the risk of adjacent level disc degeneration and segmental instability that may be seen after a cervical fusion. An essential argument in confirming the utility of cervical arthroplasty is long-term confirmation that cervical disc replacements can maintain physiological kinematics at the index and adjacent levels. The purpose of this invivo prospective study was to characterize the long-term segmental kinematic outcomes after cervical arthroplasty. Prospective cohort study. Twenty patients with a 5-year clinical follow-up who underwent anterior cervical discectomy with insertion of the Bryan cervical disc. Physiological measures (kinematic analysis of lateral neutral, flexion, and extension radiographic imaging). Twenty consecutive patients with degenerative disc disease were followed with regular radiographic imaging after implantation of the Bryan cervical disc prosthesis. Lateral neutral, flexion, and extension radiographs (n=240) were analyzed using Quantitative Motion Analysis software (Medical Metrics, Inc., Houston, TX, USA) to measure the biomechanical profile at the index level and adjacent levels up to 5 years after surgery. Parameters collected included range of motion (ROM), functional spinal unit (FSU) angle, anterior and posterior disc heights, sagittal translation, and center of rotation (COR). Biomechanics of the implanted artificial cervical disc was maintained up to 5 years with no significant changes in ROM, FSU angle, disc height, sagittal translation, and COR values when compared with early postoperative performance. Artificial discs were able to adequately restore and maintain preoperative kinematics. Early differences seen in disc height and FSU angle did not change during the duration of follow-up. No significant kyphotic changes or decrease in ROM were seen at the adjacent spinal levels. The Bryan cervical disc prosthesis provides for a durable solution for functional spinal motion at the operated level and maintained the preoperative kinematics at adjacent levels at the 5-year follow-up.

A Meta-Analysis Comparing the Results of Cervical Disc Arthroplasty with Anterior Cervical Discectomy and Fusion (ACDF) for the Treatment of Symptomatic Cervical Disc Disease

Anterior cervical discectomy and fusion is a standard treatment for symptomatic cervical disc disease, but pseudarthrosis and accelerated adjacent-level disc degeneration may develop. Cervical disc arthroplasty was developed to preserve the kinematics of the functional spinal unit. Trials comparing arthroplasty with anterior cervical discectomy and fusion have shown unclear benefits in terms of clinical results, neck motion at the operated level, adverse events, and the need for secondary surgical procedures. Only randomized clinical trials were included in this meta-analysis, and the search strategy followed the requirements of the Cochrane Library Handbook. Two reviewers independently assessed the methodological quality of each included study and extracted the relevant data. Twenty-seven randomized clinical trials were included; twelve studies were Level I and fifteen were Level II. The results of the meta-analysis indicated longer operative times, more blood loss, lower neck and arm pain scores reported on a visual analog scale, better neurological success, greater motion at the operated level, fewer secondary surgical procedures, and fewer such procedures that involved supplemental fixation or revision in the arthroplasty group compared with the anterior cervical discectomy and fusion group. These differences were significant (p < 0.05). The two groups had similar lengths of hospital stay, Neck Disability Index scores, and rates of adverse events, removals, and reoperations (p > 0.05). The meta-analysis revealed that anterior cervical discectomy and fusion was associated with shorter operative times and less blood loss compared with arthroplasty. Other outcomes after arthroplasty (length of hospital stay, clinical indices, range of motion at the operated level, adverse events, and secondary surgical procedures) were superior or equivalent to the outcomes after anterior cervical discectomy and fusion.

Ten-year survival and clinical outcome of the AcroFlex lumbar disc replacement for the treatment of symptomatic disc degeneration

We have previously reported on the osseointegration, stability, and preserved motion of the AcroFlex lumbar disc replacement (LDR) in a nonhuman primate model. Detailed biomechanical testing of the device predicted implant survival for at least 10 years of invivo use. Significant improvements in the clinical outcome were reported at 2 years. However, mechanical failure of the polyolefin rubber was detected by fine-cut computed tomography (CT) in a number of subjects within 2 years. As a result, no further devices were implanted. To report on the 10-year survival and clinical outcome of the AcroFlex elastomeric LDR when used for the treatment of one- or two-level symptomatic disc degeneration between L4 and S1. Prospective nonrandomized clinical trial with a mean 10-year follow-up. Twenty-eight patients with symptomatic disc degeneration who underwent AcroFlex LDR at one or two levels. Clinical: Visual Analog Score for back pain, Oswestry Disability Index (ODI), Low Back Outcome Score (LBOS), and Short Form-36 (SF-36). Survival: Kaplan-Meier analysis over 10 years with first revision surgery as the end point. Radiographic: Dynamic flexion/extension radiographs at 2 years. Magnetic resonance imaging (MRI) and CT scans at 10 years. Twenty-eight subjects (14 male, mean age 41 years) with symptomatic disc degeneration unresponsive to nonsurgical treatment were enrolled into a prospective nonrandomized trial of the AcroFlex LDR. Visual analog score for back pain, ODI, LBOS, and SF-36 questionnaires were administered preoperatively at 6 months, 1, 2, and 10 years after the index procedure. All subjects were invited to undergo an MRI and for those with the device remaining in situ, a lumbar CT scan. Kaplan-Meier survival analysis was performed with first revision surgery as the end point. At a mean of 9 years, 8 months (range, 8 years, 8 months-11 years, 3 months) after surgery, 17 of 28 patients did not require a revision surgery, representing a cumulative survival of 60.7%. In contrast, 11 of 28 patients (39.3%) underwent a total of 14 revision procedures; 9 of 11 patients underwent a conversion to anterior lumbar interbody fusion supplemented with pedicle screw fixation. Indications for a revision included device failure in seven and disabling pain in four patients. Mean time to revision was 3 years, 10 months (range, 23 months-8 years, 4 months). Mean ODI at 10 years for nonrevision cases was 27.5 (±17.6) compared with 41.8 (±26) for revision cases. Mean improvement over 10 years in the ODI for nonrevision cases was 17.9 (±16.9) compared with 12 (±16.1) for revision cases. Similar trends were observed in LBOS and SF-36 scores. Radiographic findings in the revision group included midsubstance tears in the rubber, osteolysis, and implant displacement. CT findings in 11 of 17 survivors included heterotopic bone formation (85%), osteolysis (50%), and subsidence (14%). Magnetic resonance imaging in 14 of 23 subjects at the final follow-up demonstrated an adjacent-level disc degeneration in 68% of those with the AcroFlex LDR in situ and in 40% of those who had been converted to fusion. Skip-level disc degeneration was present in 44% of those with AcroFlex device in situ and in 20% of those who had been converted to fusion. The cumulative survival was 60.7% at 10 years when the first revision surgery was taken as the end point. The etiology of the implant failure prompting the revision included failure of osseointegration, midsubstance elastomeric tears, and osteolysis. Further use of this implant is not justified. The incidence of adjacent-level disc degeneration for the AcroFlex was comparable with that observed adjacent to the spinal fusion. Salvage procedures involving conversion to spinal fusion are technically demanding, but appear to improve outcomes modestly.

The Fate of Facet Joint and Adjacent Level Disc Degeneration Following Total Lumbar Disc Replacement

Prospective clinical, x-ray, and magnetic resonance imaging investigation following total lumbar disc replacement (TDR) with ProDisc II (Synthes, Paoli, PA). To examine the progression of adjacent level degeneration (ALD), facet joint degeneration (FJD) as well as associated risk factors following TDR. Fusion procedures have been associated with adjacent level morbidities and facet joint pathologies in a considerable number of patients. Whether the incidence of these negative side effects can be reduced with TDR remains unestablished. Clinical outcome scores Visual Analogue Scale (VAS), Oswestry Disability Index (ODI) and patient satisfaction rates were acquired within the framework of an ongoing prospective study with ProDisc II. The mean index-level ROM was established for every patient over the entire postoperative period from multiple flexion/extension x-ray images. The progression of ALD and FJD was evaluated from pre- and postoperative magnetic resonance images by 2 independent radiologists. Results from 93 patients with an average follow-up of 53.4 months (range, 24.1-98.7 months) were included in this study. The overall results revealed a significant improvement from preoperative VAS and ODI levels (P < 0.0001).The incidence of ALD was 10.2% (n = 11/108 levels). The degenerative changes were mild and occurred late after surgery (mean, 65.2 months; range, 37.9-85.6 months). There was no significant correlation between index-level ROM and the occurrence of ALD (P > 0.05).Progression of FJD was observed in 20.0% of all facet joints (n = 44/220). FJD occurred significantly more often following TDR at the lumbosacral junction in comparison to the level above the lumbosacral junction (P < 0.02) and was observed more frequently at index-levels than at nonindex levels (P < 0.001).The degenerative changes were associated with a negative influence on postoperative outcome parameters VAS and ODI (P < 0.03) that were already detected early after surgery. The mean postoperative ROM was significantly lower in patients with progression of FJD in comparison to the remaining cohort (P < 0.0001). TDR proved to have a beneficial effect with respect to adjacent level disc preservation. The degenerative changes were mild, occurred late after surgery and did not reveal a negative effect on postoperative clinical outcome. There was no significant correlation between index-level ROM and the occurrence of ALD (P > 0.05).TDR was, however, associated with a progression of index-level FJD in a considerable number of patients, particularly at the lumbosacral junction. Lower segmental mobility and less favorable clinical results point to the fact that a particular cohort of patients may predominantly be affected in which TDR shows inferior compatibility with the index-segment's biomechanics.

Dynamic Stabilization Using X-stop Versus Transpedicular Screw Fixation in the Treatment of Lumbar Canal Stenosis; Comparative Study of the Clinical Outcome

Objective A comparative randomized prospective clinical study to compare the clinical outcome of transpedicular screw fixation and dynamic stabilization using X-stop. Background Spinal fusion has been offered to patients who suffer from lumbar spinal stenosis or spondylolisthesis. Despite improvement in fusion it significantly alters spinal biomechanics, which causes premature disc degeneration at levels neighboring fusion. Dynamic stabilization maintains or restores intervertebral motion in a controlled fashion, whether by restricting the extremes of spinal movement or by dampening the kinetic energy involved in motion. Methods This study included 60 patients who were divided into 2 equal groups (A and B) randomly assigned to undergo either transpedicular screw fixation (group A) or dynamic stabilization using X-stop (group B). Patients had degenerative spondylolisthesis or retrolisthesis (Grade I), lateral or central spinal stenosis. Participants were evaluated preoperatively, postoperatively at 3 weeks, and then at 6-month, 12-month, and 24-month intervals. Visual Analog Scale (VAS) was used to score both lower-limb and back pain. Patient functioning was evaluated using the Oswestry Disability Index (ODI). Results In group A, the mean pain and function scores improved as follows: leg pain from 80.5 to 35.5, back pain from 54 to 37.5, and ODI score from 55 to 34.5%. In group B, the mean pain and function scores improved as follows: leg pain from 82.5 to 25.5, back pain from 52 to 29.5, and ODI score from 53 to 26.5%. Conclusions The long-term outcome of dynamic stabilization is promising. The procedure is preferable to fusion because it avoids the greater tissue destruction and the morbidity of donor site problems. Adjacent-level disc degeneration after lumbar fusion has been well documented and little controversy exists as to the additional disability resulting from this proximate degenerative process.

Differences between subtotal corpectomy and laminoplasty for cervical spondylotic myelopathy

This study aimed to obtain guidelines for choosing between subtotal corpectomy (SC) and laminoplasty (LP) by analysing the surgical outcomes, radiological changes and problems associated with each surgical modality. A retrospective analysis of two interventional case series. Department of Orthopaedic Surgery, Kagawa University, Japan. Subjects comprised 34 patients who underwent SC and 49 patients who underwent LP. SC was performed by high-speed drilling to remove vertebral bodies. Autologous strut bone grafting was used. LP was performed as an expansive open-door LP. The level of decompression was from C3 to C7. Clinical evaluations included recovery rate (RR), frequency of C5 root palsy after surgery, re-operation and axial pain. Radiographic assessments included sagittal cervical alignment and bone union. Comparisons between the two groups showed no significant differences in age at surgery, preoperative factors, RR and frequency of C5 palsy. Progression of kyphotic changes, operation time and volumes of blood loss and blood transfusion were significantly greater in the SC (two- or three-level) group. Six patients in the SC group required additional surgery because of pseudoarthrosis, and four patients underwent re-operation because of adjacent level disc degeneration. In the LP group, the problem of elimination of postoperative axial symptoms remains to be solved. The merit of SC is the low frequency of axial symptoms. One-level SC can be considered to have similar degree of invasiveness as LP. Compared with SC, LP is more suitable for elderly patients with multilevel stenosis.

Does Incorrect Level Needle Localization During Anterior Cervical Discectomy and Fusion Lead to Accelerated Disc Degeneration?

Retrospective radiographic analysis. To retrospectively review a group of patients undergoing anterior cervical discectomy and fusion (ACDF) to determine the relative risk of adjacent level disc degeneration after incorrect needle localization. The needle puncture technique is a well-established method to cause disc degeneration in experimental animal studies. The risk for accelerated degeneration because of needle puncture in humans is unknown. A retrospective radiographic analysis of 87 consecutive patients after single or 2-level ACDF with anterior plate instrumentation was performed. Perioperative and follow-up radiographs were used to grade disc degeneration according to a previously described scale. Eighty-seven patients were included in the study (36 underwent 1-level ACDF, and 51 underwent 2-level ACDF). Seventy-two had correct needle localization at the level of planned surgery; 15 had incorrect needle localization (1 level above the operative level). There were no differences between the 2 groups in age, sex and length of follow-up. Patients in the incorrectly marked group were statistically more likely to demonstrate progressive disc degeneration with an odds ratio of 3.2. There was no correlation between age and length of follow-up with development of disc degeneration. There is a 3-fold increase in risk of developing adjacent level disc degeneration in incorrectly marked discs after ACDF at short-term follow-up. This may indicate that either needle related trauma or unnecessary surgical dissection contributes to accelerated adjacent segment degeneration.

145. Single Level ProDisc®-C Total Disc Replacement Up to Four Years Follow-up

BACKGROUND CONTEXT: Cervical total disc replacement (TDR) is an alternative to Anterior Cervical Discectomy and Fusion (ACDF) for the treatment of symptomatic cervical disc disease (SCDD). Cervical TDR has potential benefits of reducing adjacent level disc degeneration and maintaining range of motion (ROM) between vertebral bodies. Long-term study results are needed to quantify these benefits.

Stress Reduction in Adjacent Level Discs via Dynamic Instrumentation: A Finite Element Analysis

Background Conventional (rigid) fusion instrumentation is believed to accelerate the degeneration of adjacent discs by increasing stresses caused by motion discontinuity. Fusion instrumentation that employs reduced rod stiffness and increased axial motion, or dynamic instrumentation, may partially alleviate this problem, but the effects of this instrumentation on the stresses in the adjacent disc are unknown. We used a finiteelement model to calculate and compare the stresses in the adjacent-level disc that are induced by rigid and dynamic posterior lumbar fusion instrumentation.