Predicting the risk of adjacent segment pathology in the cervical spine: a systematic review.

By London Spine
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Predicting the risk of adjacent segment pathology in the cervical spine: a systematic review.

Spine (Phila Pa 1976). 2012 Oct 15;37(22 Suppl):S52-64

Authors: Lawrence BD, Hilibrand AS, Brodt ED, Dettori JR, Brodke DS

Abstract
STUDY DESIGN: Systematic review.
OBJECTIVE: We performed a systematic review to determine the risk and to define potential identifiable risk factors for the development of adjacent segment pathology (ASP) after cervical fusion surgery.
SUMMARY OF BACKGROUND DATA: During the past several decades, the indications for spinal arthrodesis have expanded, with a dramatic increase in the rate of cervical spine fusion in the United States during the past decade. However, as more of these procedures are performed over time, there have been concerns regarding the potential for these patients to develop changes at levels adjacent to the index procedure. Questions remain whether the development of clinical ASP (CASP) are iatrogenic in nature or part of natural history.
METHODS: A systematic review of the literature was undertaken for articles published in English language between 1990 and March 15, 2012. Electronic databases and reference lists of key articles were searched to identify articles reporting risk factors for CASP after cervical fusion. Two independent reviewers assessed the level of evidence and the overall quality of the literature using the Grades of Recommendation Assessment, Development, and Evaluation criteria. Disagreements were resolved by consensus.
RESULTS: We identified 5 studies (4 retrospective cohorts, 1 database study) from our search strategy that met the inclusion criteria from a total of 176 possible studies for review. The prevalence of CASP ranged from 11% to 12% at 5 years, 16% to 38% at 10 years, and 33% at 17 years. Factors that may contribute to the development of CASP include age less than 60 years, fusing adjacent to the C5-C6 and/or C6-C7 levels, a pre-existing disc herniation, and/or dural compression secondary to spinal stenosis with a mean anteroposterior diameter spinal canal of 13 mm or smaller.
CONCLUSION: CASP remains a controversial topic despite multiple attempts of elucidating an iatrogenic effect of spinal fusion versus the natural history of spinal degeneration. The mean rate of the development of symptomatic degeneration in the cervical spine after arthrodesis is estimated between 1.6% and 4.2% per year. The mean rate of reoperation for CASP is estimated at 0.8% per year. In addition, fusing adjacent to but not including the C5-C6 and/or C6-C7 disc spaces seems to consistently increase the risk of developing CASP.
CONSENSUS STATEMENT: 1. The risk of developing new symptoms secondary to adjacent segment pathology causing radiculopathy and/or myelopathy after cervical fusion surgery ranges from a cumulative rate of 1.6% to 4.2% per year. Strength of Statement: Strong. 2. The risk of developing adjacent-level symptoms may be increased if disc protrusion, disc degeneration, or cord effacement is present at C5–C6 and/or C6–C7 and if those levels are adjacent to the planned surgical level. Strength of Statement: Strong.

PMID: 22885828 [PubMed – in process]

Progressive disc degeneration at C5-C6 segment affects the mechanics between disc heights and posterior facets above and below the degenerated segment: A flexion-extension investigation using a poroelastic C3-T1 finite element model.

By London Spine

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Progressive disc degeneration at C5-C6 segment affects the mechanics between disc heights and posterior facets above and below the degenerated segment: A flexion-extension investigation using a poroelastic C3-T1 finite eleme…

Clinical evaluation of the stability of single-segment short pedicle screw fixation for the reconstruction of lumbar and sacral tuberculosis lesions.

By London Spine
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Clinical evaluation of the stability of single-segment short pedicle screw fixation for the reconstruction of lumbar and sacral tuberculosis lesions.

Arch Orthop Trauma Surg. 2012 Oct;132(10):1429-35

Authors: Jin W, Wang Z

Abstract
INTRODUCTION: The routine surgical approach to posterior reconstruction in spinal tuberculosis is short- or long-segment fixation and/or fusion. This method sacrifices movement at more than one vertebral level, limits normal movement of the spinal column, and leads to degeneration of the small joints of the adjacent levels. Surgical techniques that reduce the number of fixed vertebral levels and maximize the retention of movement of the spinal column are of current interest in the treatment of spinal tuberculosis.
MATERIALS AND METHODS: A total of 106 patients with lumbosacral tuberculosis were randomly divided into two groups: a single-segment fixation group and a short-segment fixation group. After posterior correction and internal fixation, all patients underwent anterior radical debridement and interbody fusion with bone grafting.
RESULTS: The mean postoperative follow-up period was 58.09 ± 17.01 months. The average bone graft healing time was 4.35 ± 1.04 months in the single-segment group and 4.47 ± 1.10 months in the short-segment group. In the single-segment group, correction of the Cobb angle was 14.47 ± 3.76° and the loss rate was 7.22 %, and in the short-segment group, correction of the Cobb angle was 16.20 ± 2.70° and the loss rate was 6.37 % (P < 0.05). Patients with operative time, blood loss, costs in the single-segment group were significantly reduced than the short-segment group (P < 0.05).
CONCLUSIONS: Single-segment pedicle screw fixation and correction surgery can fix and fuse the diseased segment in lumbar and sacral tuberculosis, retain normal movement in the adjacent spinal column, and promote functional recovery of the spinal column postoperatively. It was be regarded as a cost-effective means of treatment with lumbar and sacral tuberculosis.

PMID: 22736022 [PubMed – indexed for MEDLINE]

Adjacent segment disease and C-ADR: promises fulfilled?

By London Spine
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Adjacent segment disease and C-ADR: promises fulfilled?

Evid Based Spine Care J. 2012 Feb;3(S1):39-46

Authors: Riew KD, Schenk-Kisser JM, Skelly AC

Abstract
Study design: Systematic review.Clinical question: Do the rates and timing of adjacent segment disease (ASD) differ between cervical total disc arthroplasty (C-ADR) and anterior cervical discectomy and fusion (ACDF) in patients treated for cervical degenerative disc disease?Methods: A systematic search of MEDLINE/PubMed and bibliographies of key articles was done to identify studies with long-term follow-up for symptomatic and/or radiographic ASD comparing C-ADR with fusion for degenerative disc disease of the cervical spine. The focus was on studies with longer follow-up (48-60 months) of primary US Food and Drug Administration trials of Prestige ST, Prodisc-C, and Bryan devices as available. Trials of other discs with a minimum of 24 months follow-up were considered for inclusion. Studies evaluating lordosis/angle changes at adjacent segments and case series were excluded.Results: From 14 citations identified, four reports from three randomized controlled trials and four nonrandomized studies are summarized. Risk differences between C-ADR and ACF for symptomatic ASD were 1.5%-2.3% and were not significant across RCT reports. Time to development of ASD did not significantly differ between treatments. Rates of radiographic ASD were variable. No meaningful comparison of ASD rates based on disc design was possible. No statistical differences in adjacent segment range of motion were noted between treatment groups.Conclusion: Our analysis reveals that, to date, there is no evidence that arthroplasty decreases ASD compared with ACDF; the promise of arthroplasty decreasing ASD has not been fulfilled.

PMID: 23236312 [PubMed]

Symptomatic adjacent segment disease after cervical total disc replacement: re-examining the clinical and radiological evidence with established criteria.

By London Spine
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Symptomatic adjacent segment disease after cervical total disc replacement: re-examining the clinical and radiological evidence with established criteria.

Spine J. 2013 Jan;13(1):5-12

Authors: Nunley PD, Jawahar A, Cavanaugh DA, Gordon CR, Kerr EJ, Utter PA

Abstract
BACKGROUND CONTEXT: Although several publications in the last decade have proved equality in safety and efficacy of the total disc replacement (TDR) to the anterior fusion procedure in cervical spine, the claim that TDR may reduce the incidence of adjacent segment disease (ASD) has not been corroborated by clinical evidence.
PURPOSE: We attempt to predict the true incidence of symptomatic ASD after TDR surgery in the cervical spine at one or two levels at a median follow-up period of 4 years.
STUDY DESIGN: A total of 763 patients were screened to participate in four different Food and Drug Administration device exemption trials for artificial cervical disc replacement at three collaborating institutions. Two hundred seventy-one patients qualified and enrolled in the trials. One hundred seventy-three randomized to receive artificial disc replacement surgery, and 167 have completed a 4-year or longer follow-up.
OUTCOME MEASURES: Patients experiencing cervical radiculopathy symptoms in the follow-up period were worked-up with clinical examinations, magnetic resonance imaging of the cervical spine, and other diagnostic studies. Once a clinical correlation was established with the imaging evidence of adjacent segment degeneration, a careful record was maintained to document the subsequent medical and/or surgical treatment received by these patients. Statistical analysis was performed to determine the true incidence of and factors affecting the ASD after cervical disc replacement in these patients.
RESULTS: Twenty-six patients (15.2%) were identified to satisfy our criteria for ASD at the median follow-up of 51 months, with the annual incidence of 3.1% as calculated by life tables. The actuarial 5-year freedom from ASD rate was 71.6%±0.6%, and the mean period for freedom from ASD was 70.4±2.1 months.
CONCLUSIONS: The incidence of symptomatic ASD after cervical TDR is 3.1% annually regardless of the patient’s age, sex, smoking habits, and design of the TDR device. The presence of osteopenia and lumbar degenerative disease significantly increase the risk of developing ASD after anterior cervical surgery.

PMID: 23318108 [PubMed – in process]

Systems for long-segment percutaneous spinal fixation: technical feasibility for various indications.

By London Spine
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Systems for long-segment percutaneous spinal fixation: technical feasibility for various indications.

Acta Neurochir (Wien). 2011 May;153(5):985-91

Authors: Blondel B, Fuentes S, Tropiano P, Roche P, Métellus P, Dufour H

Abstract
SUMMARY OF BACKGROUND DATA: New methods of spinal percutaneous fixation are developing very rapidly. However, few studies to date have focused on long-segment methods of instrumentation.
OBJECTIVE: To report the technical feasibility of long-segment percutaneous stabilization for various indications.
METHODS: The study included 24 patients with a mean age of 58 years (range 38-79). The etiologies included trauma, infection, tumors, or pathology secondary to degenerative lumbar scoliosis. The damaged vertebrae ranged from T5 to L4. All of the patients underwent posterior percutaneous long-segment fixation. When necessary, the anterior spinal column was stabilized by balloon kyphoplasty or via anterior approach. The results obtained were analyzed on the basis of clinical and radiological criteria.
RESULTS: The constructs involved four levels on average per patient, located between T3 and S1. No extra-pedicular misplacements were observed. Two technical difficulties were noticed without clinical consequences. A significant improvement in the pain levels was obtained in all the patients in this series.
CONCLUSIONS: Long-segment percutaneous fixation was found to be technically feasible and to considerably improve the patients’ spinal deformations. When associated with balloon kyphoplasty, this intervention seems to provide less loss of correction than previous methods, and posterior fusion was therefore not required. As with all new methods, there is a learning curve, and the indications have to be strictly observed. Further studies need to be performed, however, with a longer follow-up to confirm the absence of long-term complications.

PMID: 21369948 [PubMed – indexed for MEDLINE]