Adjacent Segment Instability Research Articles

Is it necessary to extend fusion to L4 when correcting pediatric L5-S1 spondylolisthesis?

The objective of this study was to investigate whether extending fusion to L4 is imperative in the surgical treatment of pediatric L5-S1 spondylolisthesis. This retrospective analysis encompassed 68 pediatric cases of dysplastic L5-S1 spondylolisthesis who underwent posterior lumbar interbody fusion surgery at two hospitals. Patients were categorized into two groups based on the upper instrumented vertebra (group L4 and group L5). Data were collected from medical records and radiological images obtained preoperatively and at last follow-up. Radiographic parameters including slip percentage (SP), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), Spinal Deformity Study Group dysplastic lumbosacral angle (SDSG-LSA), pelvic tilt (PT), Dubousset's lumbosacral angle (Dub-LSA), sacral slope (SS), and severity index (SI) were measured. Surgery-related data and complication data were also collected. The incidence rates of complications were compared, including those of neurological deficit, adjacent-segment instability (ASI), and other complications. ASI was defined as progression of slippage > 3 mm or posterior opening > 5° in the adjacent segment. Clinical outcomes were assessed with the numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores. The follow-up period for all patients lasted a minimum of 2 years. Among all 68 patients, group L4 consisted of 15 patients and group L5 comprised 53 patients. The patients included in both groups had comparable baseline demographic characteristics and radiographic parameters. Postoperative SP and SDSG-LSA were significantly lower in group L5 (p < 0.05). No other postoperative radiographic differences were observed between groups. One patient in group L4 and 3 patients in group L5 experienced transient neurological deficits (p > 0.05). There were 13 cases of ASI in group L5 compared with none in group L4 (24.5% vs 0%, p > 0.05). Of the 13 patients with ASI, 4 underwent revision surgery due to L4-5 level instability and clinical symptoms. The remaining individuals exhibited no symptoms, and regular annual follow-up assessments are being conducted for all patients. The NRS and ODI scores at final follow-up did not exhibit any significant differences between the two groups. Fusion to L5 could achieve comparable satisfactory results to fixation to L4, albeit with increased likelihood of ASI. Extension of fusion to L4 may not be necessary for most patients with pediatric L5-S1 spondylolisthesis.

Biomechanical Effect of Hybrid Dynamic Stabilization Implant on the Segmental Motion and Intradiscal Pressure in Human Lumbar Spine.

The hybrid dynamic stabilization system, Dynesys-Transition-Optima, represents a novel pedicle-based construct for the treatment of lumbar degenerative disease. The theoretical advantage of this system is to stabilize the treated segment and preserve the range of motion within the adjacent segment while potentially decreasing the risk of adjacent segment disease following lumbar arthrodesis. Satisfactory short-term outcomes were previously demonstrated in the Dynesys-Transition-Optima system. However, long-term follow-up reported accelerated degeneration of adjacent segments and segmental instability above the fusion level. This study investigated the biomechanical effects of the Dynesys-Transition-Optima system on segment motion and intradiscal pressure at adjacent and implanted levels. Segmental range of motion and intradiscal pressure were evaluated under the conditions of the intact spine, with a static fixator at L4-5, and implanted with DTO at L3-4 (Dynesys fixator) and L4-5 (static fixator) by applying the loading conditions of flexion/extension (±7.5 Nm) and lateral bending (±7.5 Nm), with/without a follower preload of 500 N. Our results showed that the hybrid Dynesys-Transition-Optima system can significantly reduce the ROM at the fusion level (L4-L5), whereas the range of motion at the adjacent level (L3-4) significantly increased. The increase in physiological loading could be an important factor in the increment of IDP at the intervertebral discs at the lumbar spine. The Dynesys-Transition-Optima system can preserve the mobility of the stabilized segments with a lesser range of motion on the transition segment; it may help to prevent the occurrence of adjacent segment degeneration. However, the current study cannot cover all the issues of adjacent segmental diseases. Future investigations of large-scale and long-term follow-ups are needed.

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

BACKGROUND CONTEXTCervical 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. PURPOSETo investigate the 10-year follow-up adverse events rates between CDA and ACDF. STUDY DESIGN/SETTINGThe 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. PATIENT SAMPLEn=463 patients. OUTCOME MEASURESAdverse events comparison of CDA and ACDF from self-reported and physiologic measures. METHODSAt 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. RESULTSA 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). CONCLUSIONSThe 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.

Revision Strategy of Symptomatic Lumbar Adjacent Segment Degeneration: Full Endoscopic Decompression versus Extended Posterior Interbody Fusion

We evaluated the clinical and imaging outcomes of full endoscopic lumbar decompression (FELD) compared with extended posterior lumbar interbody fusion (PLIF) for adjacent segment degeneration (ASD) after fusion surgery and developed a revision strategy. The present retrospective study enrolled 65 patients with ASD who had undergone FELD (n= 31) or extended PLIF (n= 34) from January 2014 to January 2018. Clinical evaluations had been performed preoperatively and at 3, 12, and 24 months postoperatively and included the Oswestry disability index, Japanese Orthopaedic Association score for function assessment, and visual analog scale scores for pain. Imaging evaluations were performed preoperatively, immediately after surgery, and at the last follow-up examination. No significant differences were found in the baseline data between the FELD and PLIF groups (P > 0.05), except for the proportion of patients with radiographic adjacent segment instability (P < 0.05). The mean operative time, blood loss, and length of hospital stay were significantly decreased for the FELD group (P < 0.001). For patients with stable ASD, no significant differences were found in the clinical outcome between the 2 groups (P > 0.05). The PLIF group had significantly restored disc height after surgery (P < 0.05). For patients with unstable ASD, the low back and leg pain of the PLIF group were more significantly relieved compared with the FELD group within 3-24 months postoperatively (P < 0.05). The function of the PLIF group had significantly improved within 12 months postoperatively (P < 0.05). The use of FELD achieved satisfactory outcomes for the treatment of radiographic stable ASD, which were not worse than those with PLIF. With less trauma and faster recovery, FELD could be an alternative option.

Is Initial Posterior Atlantoaxial Fixation and Fusion Applying Bilateral C1-2 Transarticular Screws and C1 Laminar Hooks Reliable for Acute Pediatric Atlantoaxial Instability?: A Minimal 10-Year Analysis of Outcome and Radiological Evaluation.

A retrospective case series study with at least 10 years of follow-up data. To validate the reliability of bilateral C1-2 transarticular screws and C1 laminar hooks and a bone autograft for acute pediatric atlantoaxial instability. The reliability of initial posterior atlantoaxial fusion in pediatric patients is still controversial. To date, however, only a few published articles with short-term follow-up data are available to help spinal surgeons understand the effects of posterior atlantoaxial fusion in the skeletally immature spine. Five pediatric patients with acute atlantoaxial instability underwent atlantoaxial fusion using the above technique over a 3-year period. During a minimum 10-year follow-up period, not only outcomes and complications were investigated, but the vertical growth of the constructed spine in relation to the growth of the entire cervical spine, overall cervical spinal alignment, and adjacent-segment instability were evaluated. The clinical follow-up indicated solid fusion and complete clinical relief from symptoms. No neural or vascular impairment was observed. The radiological evaluation showed that all patients had growth within the fusion construct reaching a mean 35.4% of the entire cervical spine. There were no radiological indicators of subaxial instability, even when cervical sagittal alignments became straight with a mean C2-7 angle of 6.4°. The results showed that initial posterior atlantoaxial fusion accomplished with bilateral C1-2 transarticular screws, C1 laminar hooks fixation, and bony autograft is a reliable surgical technique for treating acute pediatric atlantoaxial instability without negative effects on vertical growth at the fused level or the stability of the subaxial spine. 3.

The impact of spinopelvic parameters on the rate of adjacent segment instability after short-segment spinal fusion

The objective of this study is to determine the impact of postoperative spinopelvic parameters on the development of adjacent segment instability after single-level lumbar fusion. A total of 116 patients with degenerative spine conditions after lumbar fusion were enrolled in this study and subdivided into two groups. Group I consisted of 24 patients with signs of adjacent segment instability; Group II included 92 patients without signs of instability. The minimal follow-up period was 24 months. The mean postoperative lumbar lordotic (LL) angle in both groups was within the normal range (-60.9±12); no statistically significant intergroup differences were revealed (56.6±12.1 and 58.4±11.2 for Groups I and II, respectively; p=0.314). In Group I patients, the mean pelvic incidence (PI) angle differed significantly from the mean PI values in Group II patients (70.4±7.6 and 53.2±8.4, respectively; p=0.006) and from the normal PI values (51.9±10). Therefore, the mean difference between PI and LL (PI-LL) angles in the Group I patients was significantly higher than in Group II (16.2±5.4 and 4.8±8.6, respectively; p=0.004). Significant PI-LL mismatch (PI-LL ≥10°) was observed in 22 (91.7%) patients in Group I and in 11 (11.95%) patients in Group II. According to regression analysis data, the PI-LL mismatch was identified as a risk factor for adjacent segment instability; the odds ratio =4.2; 95% confidence interval 1.46-12.25; and p=0.007. Patients with the high PI value and low LL value have a significantly higher risk of adjacent segment instability after short-segment spinal fusion.

Clinical and Radiological Outcomes of Day-care Posterior Foraminotomy and Decompression of the Cervical Spine.

Purpose:Anterior cervical procedures are associated with many intra- and post-operative complications leading to long-term patient morbidity. In this study, we have evaluated the clinical and radiological Outcome of day care posterior cervical foraminotomy in patients with single-level cervical radiculopathy with or without neurodeficit.Materials and Methods:Seventeen patients underwent single-level posterior cervical foraminotomy for radicular symptoms were studied between June 2011 and May 2016. Clinical outcome was studied by visual analog scale (VAS) score, neck disability index (NDI), and Odom's criteria. Adjacent segment degeneration was evaluated on lateral cervical radiograph at every follow-up by calculating the focal and global angulation of the cervical spine and disc height at the operated level and adjacent segments. Dynamic lateral cervical spine radiograph was done to evaluate segmental instability.Results:After a mean follow-up duration of 30.64 months, 13 patients had excellent, three patients had good, and one patient had fair outcome as per Odom's criteria. The mean VAS score for radicular pain, neck pain, and NDI was significantly reduced postoperatively (P < 0.001). The mean focal angulation, mean global angulation, the disc height at operated and adjacent level were not changed significantly (P > 0.05). There was no instability noted postoperatively on lateral dynamic cervical spine radiographs. There was no complication in our study.Conclusion:Posterior cervical foraminotomy is an effective surgical method for treatment of patients with single-level cervical radiculopathy and helps to achieve good clinical and radiological outcome, prevents postoperative adjacent segment degeneration and instability with minimal complications.

The impact of obesity measured by outer abdominal fat on instability of the adjacent segments after rigid pedicle screw fixation.

Previous studies have shown coherence between obesity and higher rates of complications following spinal surgery. However, there is a lack of information about the influence of obesity and the mass of outer abdominal fat (OAF) on adjacent segment instability after spinal fusion surgery. Radiographs of 194 patients with spinal fusion surgery were assessed retrospectively. Radiographs were performed after surgery during two years’ follow-up and signs of adjacent segment instability were documented. Patients were classified regarding their BMI and extent of OAF was assessed using CT at the umbilical level. In 20 patients (10.3%) instability of adjacent segments occurred during followup. In this cohort mean OAF was significantly thicker (28.07 mm) compared to the patients without instability (22.39) (P=0.038). A total of 45% of patients with instability showed OAF of more than 30 mm at time of intervention compared to 10% in those without signs of instability. There exists significant correlation between the extent of OAF and development of adjacent segment instability postoperatively. Thus, weight reduction before spinal surgery could potentially decrease risk of adjacent segment instability.

Growth and alignment of the pediatric subaxial cervical spine following rigid instrumentation and fusion: a multicenter study of the Pediatric Craniocervical Society.

OBJECTIVE The long-term effects of surgical fusion on the growing subaxial cervical spine are largely unknown. Recent cross-sectional studies have demonstrated that there is continued growth of the cervical spine through the teenage years. The purpose of this multicenter study was to determine the effects of rigid instrumentation and fusion on the growing subaxial cervical spine by investigating vertical growth, cervical alignment, cervical curvature, and adjacent-segment instability over time. METHODS A total of 15 centers participated in this multi-institutional retrospective study. Cases involving children less than 16 years of age who underwent rigid instrumentation and fusion of the subaxial cervical spine (C-2 and T-1 inclusive) with at least 1 year of clinical and radiographic follow-up were investigated. Charts were reviewed for clinical data. Postoperative and most recent radiographs, CT, and MR images were used to measure vertical growth and assess alignment and stability. RESULTS Eighty-one patients were included in the study, with a mean follow-up of 33 months. Ninety-five percent of patients had complete clinical resolution or significant improvement in symptoms. Postoperative cervical kyphosis was seen in only 4 patients (5%), and none developed a swan-neck deformity, unintended adjacent-level fusion, or instability. Of patients with at least 2 years of follow-up, 62% demonstrated growth across the fusion construct. On average, vertical growth was 79% (4-level constructs), 83% (3-level constructs), or 100% (2-level constructs) of expected growth. When comparing the group with continued vertical growth to the one without growth, there were no statistically significant differences in terms of age, sex, underlying etiology, surgical approach, or number of levels fused. CONCLUSIONS Continued vertical growth of the subaxial spine occurs in nearly two-thirds of children after rigid instrumentation and fusion of the subaxial spine. Failure of continued vertical growth is not associated with the patient's age, sex, underlying etiology, number of levels fused, or surgical approach. Further studies are needed to understand this dichotomy and determine the long-term biomechanical effects of surgery on the growing pediatric cervical spine.

Lateral Lumbar Interbody Fusion and in Situ Screw Fixation for Rostral Adjacent Segment Stenosis of the Lumbar Spine.

ObjectiveThe purpose of this study is to describe the detailed surgical technique and short-term clinical and radiological outcomes of lateral lumbar interbody fusion (LLIF) and in situ lateral screw fixation using a conventional minimally invasive screw fixation system (MISF) for revision surgery to treat rostral lumbar adjacent segment disease.MethodsThe medical and radiological records were retrospectively reviewed. The surgery was indicated in 10 consecutive patients with rostral adjacent segment stenosis and instability. After the insertion of the interbody cage, lateral screws were inserted into the cranial and caudal vertebra using the MISF through the same LLIF trajectory. The radiological and clinical outcomes were assessed preoperatively and at 1, 3, 6, and 12 months postoperatively.ResultsThe median follow-up period was 13 months (range, 3–48 months). Transient sensory changes in the left anterior thigh occurred in 3 patients, and 1 patient experienced subjective weakness; however, these symptoms normalized within 1 week. Back and leg pain were significantly improved (p<0.05). In the radiological analysis, both the segmental angle at the operated segment and anterior disc height were significantly increased. At 6 months postoperatively, solid bony fusion was confirmed in 7 patients. Subsidence and mechanical failure did not occur in any patients.ConclusionThis study demonstrates that LLIF and in situ lateral screw fixation may be an alternative surgical option for rostral lumbar adjacent segment disease.

Biomechanical testing of a PEEK-based dynamic instrumentation device in a lumbar spine model

BackgroundThe purpose of this study was to investigate the range-of-motion after posterior polyetheretherketone-based rod stabilisation combined with a dynamic silicone hinge in order to compare it with titanium rigid stabilisation. MethodsFive human cadaveric lumbar spines with four vertebra each (L2 to L5) were tested in a temperature adjustable spine-testing set-up in four trials: (1) native measurement; (2) kinematics after rigid monosegmental titanium rod instrumentation with anterior intervertebral bracing of the segment L4/5; (3) kinematics after hybrid posterior polyetheretherketone rod instrumentation combined with a silicone hinge within the adjacent level (L3/4) and (4) kinematics after additional decompression with laminectomy of L4 and bilateral resection of the inferior articular processes (L3). During all steps, the specimens were loaded quasi-statically with 1°/s with pure moment up to 7.5Nm in flexion/extension, lateral bending and axial rotation. FindingsIn comparison to the native cadaveric spine, both the titanium device and polyetheretherketone-based device reduce the range-of-motion within the level L4/5 significantly (flexion/extension: reduction of 77%, p<0.001; lateral bending: reduction of 62%, p<0.001; axial rotation: reduction of 71%, p<0.001). There was a clear stabilisation effect after hybrid-instrumentation within the level L3/4, especially in flexion/extension (64%, p<0.001) and lateral bending (62%, p<0.001) but without any effect on the axial rotation. Any temperature dependency has not been observed. InterpretationSurprisingly, the hybrid device compensates for laminectomy L4 and destabilising procedure within the level L3/4 in comparison to other implants. Further studies must be performed to show its effectiveness regarding the adjacent segment instability.

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

ObjectivesCervical 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 MethodsA 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). ResultsPatients 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. ConclusionPatients 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.

Risk factors for adjacent segment pathology requiring additional surgery after single-level spinal fusion: impact of pre-existing spinal stenosis demonstrated by preoperative myelography.

We determined the incidence of and risk factors for clinical adjacent segment pathology (C-ASP) requiring additional surgeries among patients previously treated with one-segment lumbar decompression and fusion surgery. We retrospectively analysed 161 consecutive patients who underwent one-segment lumbar decompression and fusion surgery for L4 degenerative spondylolisthesis. Patient age, sex, body mass index (BMI), facet orientation and tropism, laminar inclination angle, spinal canal stenosis ratio [on myelography and magnetic resonance imaging (MRI)], preoperative adjacent segment instability, arthrodesis type, pseudarthrosis, segmental lordosis at L4-5, and the present L4 slip were evaluated by a log-rank test using the Kaplan-Meier method. A multivariate Cox proportional-hazards model was used to analyse all factors found significant by the log-rank test. Of 161 patients, 22 patients (13.7%) had additional surgeries at cranial segments located adjacent to the index surgery's location. Pre-existing canal stenosis ≥47% at the adjacent segment on myelography, greater facet tropism, and high BMI were significant risk factors for C-ASP. The estimated incidences at 10years postoperatively for each of these factors were 51.3, 39.6, and 32.5%, and the risks for C-ASP were 4.9, 3.7, and, 3.1 times higher than their counterparts, respectively. Notably, spinal canal stenosis on myelography, but not on MRI, was found to be a significant risk factor for C-ASP (log-rank test P<0.0001 and 0.299, respectively). Pre-existing spinal stenosis, greater facet tropism, and higher BMI significantly increased C-ASP risk. Myelography is a more accurate method for detecting latent spinal canal stenosis as a risk factor for C-ASP.

Laminoplasty and Pedicle Screw Fixation for Cervical Myelopathy Associated With Athetoid Cerebral Palsy

Retrospective case series. To evaluate the outcomes after laminoplasty and posterior spinal fusion using pedicle screws for cervical myelopathy associated with athetoid cerebral palsy. A variety of surgical procedures have been reported including decompression without fusion, spinal fusion by anterior, posterior, or circumferential approach in this population. However, involuntary neck movements bring risk of postoperative neurological deterioration due to progression of kyphosis, pseudoarthrosis, or adjacent segmental degeneration. A consecutive series of 17 patients who underwent midline T-saw laminoplasty and posterior spinal fusion using pedicle screws were retrospectively reviewed. The mean age was 52 years (8 females and 9 males) at the time of surgery. The mean follow-up was 71 months. Radiographical measures were made in change of Cobb angle of sagittal plane from C2 to C7 and accuracy of pedicle screws. Barthel Index that shows independence in activities of daily life and the Japanese Orthopaedic Association score were also evaluated. Preoperative Cobb angle of sagittal plane from C2 to C7 measured 11.0°± 14.5° of kyphosis, which improved to 1.5°± 12.7° postoperatively (P < 0.05). Solid posterior bony fusion was achieved in all cases without rigid orthosis such as halo vest. There were 2 cases of adjacent segmental instability, which required additional surgery. Nineteen (13%) out of the 138 screws showed deviation from the pedicle with postoperative computed tomography. However, there were no neurovascular complications during or after the surgery in any cases. Postoperative Japanese Orthopaedic Association score and Barthel Index significantly improved in 32% ± 16%, and 48% ± 26%, respectively. Laminoplasty and pedicle screw fixation provided strong internal fixation and improved neurological function and activities of daily living for cervical myelopathy associated with athetoid cerebral palsy. 4.

Komplikationsanalyse von spinalen Eingriffen bei adulten zentralen Bewegungsstörungen und Skoliosen

Adult central movement disorders, malpostures, and scolioses can have their cause in various neurological underlying diseases such as Morbus Parkinson, Pisa syndrome, or segmental dystonia. Important clinical characteristics are marked postural distortions such as camptocormia (bent spine) or laterocollis. In cases of these adult scolioses, surgical spine treatment puts high demands on the surgeon. Surgery in Parkinson's disease, for example, is associated with serious surgery-specific as well as general complications. The more rarely occurring Pisa syndrome is an entity primarily requiring medical therapy. A series of ten case reports of patients with Morbus Parkinson and Pisa syndrome who underwent spinal surgery is presented and discussed. From these reports, treatment recommendations have been derived and complemented by references from the literature. An extensive MEDLINE search was performed for this purpose. In patients suffering from Parkinson's disease, even minor surgical interventions can lead to instability of whole spine segments or even the entire spine. Implant loosening, adjacent segment instability, general perioperative complications, and progressive malposture due to disease progress can bring forth disastrous treatment courses. Spinal fixation should be performed long-segmented in combination with ventral stabilisation. Due to osteoporosis, pedicle screw cement augmentation is recommended in this collective. If the diagnosis of Pisa syndrome is established, an optimised preoperative preparation should be initiated in close cooperation with neurologists. In many cases medical therapy is sufficient and surgical interventions can be avoided.

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

Background contextCervical 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. PurposeThe purpose of this in vivo prospective study was to characterize the long-term segmental kinematic outcomes after cervical arthroplasty. Study design/settingProspective cohort study. Patient sampleTwenty patients with a 5-year clinical follow-up who underwent anterior cervical discectomy with insertion of the Bryan cervical disc. Outcome measuresPhysiological measures (kinematic analysis of lateral neutral, flexion, and extension radiographic imaging). MethodsTwenty 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). ResultsBiomechanics 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. ConclusionsThe 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.

Preoperative Facet Fluid Correlates with Cranial Adjacent Segment Instability Following Posterior Lumbar Interbody Fusion: A Minimum Two-Year Follow-Up

Spinal fusion often causes complications in adjacent segments. There is a possibility that lumbar facet fluid (FF) detected on MRI may indicate instability, even if the instability is not measurable on decubitus flexion/extension films. Although FF is occasionally observed pre-operatively at cranial adjacent segments, it is not known whether a pre-existence of FF would affect postoperative instability following fusion lumbar spine surgery.

Surgical treatment of complex axis fractures with adjacent segment instability

This study investigates the clinical and radiographic characteristics of complex axis fractures with adjacent segment instability and describes the outcome of surgical treatment. Twenty-one patients (14 male, seven female; mean age=34years) with complex axis fractures and adjacent segment instability who were treated between August 2003 and June 2009 were retrospectively reviewed. Treatment selection was based on fracture type and stability of the upper cervical segments. All patients were immobilized with a hard collar for three months after surgery. The mean follow-up period was 12months (range=6–36months). No intraoperative surgery-related complications were observed and fusion was achieved in all patients. The outcome was excellent for 17 patients, good for two patients, fair for one patient, and poor for one patient. The upper cervical segments that can become unstable due to complex axis fractures include the atlantoaxial and C2–3 joints. Recommended surgical treatments produce good results.

Mechanical Instability On Lumbar Spine At The Adjacent And Subjacent Segment After Rigid Fixation

To investigate the effect of PLIF and after rigid fixation on adjacent segment and subjacent mechanical instability moreover under loading adjacent and subjacent segment mechanical behavior. Eleven fresh-frozen lamb lumbar spines (Sacrum-T12) were loaded, in axial, flexion-extension, right-left bending directions. All specimens were tested intact and after implantation with posterior pedicle screws and rod fixation. All specimens were fixed in a biomechanical test frame. The biomechanical tests were performed by using the axial compression testing machine. The displacements between S1 and L5 of markers were measured superior-inferior displacement and anterior-posterior displacement with two non-contact CCD cameras. The axial compression was applied to each specimen with testing machine was used to generate an increasing moment up to 8400 Nmm in flexion and extension right left bending and axial compression. The load was applied to each specimen consecutively before and after intact spine and implanted rigid fixation. In all direction after rigid fixation of spine adjacent and subjacent segment (S1-L5, L5-L4) vertical (superiorinferior) displacements were lower but anterior-posterior displacements were higher. Displacement values were evaluated and compared statistically. When we checked the statistical data, there were numerical differences and there was significant change between the intact spine and the spine implanted pedicular screws and rods. Biomechanical alterations likely play a primary role in causing adjacent and subjacent segment disease. After rigid fixation adjacent and subjacent mobile segment (anterior-posterior) displacement of the lumbar spine was significantly greater than intact spine. Rigid fixation of lumbar spine alters adjacent and subjacent segment level ROM. Therefore abnormal stress and hyper mobility on adjacent and subjacent segment may cause spinal instability, which may develop facet joint degeneration and low back pain.