Showing papers in "Spine in 2008"

Interpreting change scores for pain and functional status in low back pain: towards international consensus regarding minimal important change.

Abstract: Study Design. Literature review, expert panel, and a workshop during the "VIII International Forum on Primary Care Research on Low Back Pain" (Amsterdam, June 2006). Objective. To develop practical guidance regarding the minimal important change (MIC) on frequently used measures of pain and functional status for low back pain. of Background Data. Empirical studies have tried to determine meaningful changes for back pain, using different methodologies. This has led to confusion about what change is clinically important for commonly used back pain outcome measures. Methods. This study covered the Visual Analogue Scale (0-100) and the Numerical Rating Scale (0-10) for pain and for function, the Roland Disability Questionnaire (0-24), the Oswestry Disability Index (0-100), and the Quebec Back Pain Disability Questionnaire (0-100). The literature was reviewed for empirical evidence. Additionally, experts and participants of the VIII International Forum on Primary Care Research on Low Back Pain were consulted to develop international consensus on clinical interpretation. Results. There was wide variation in study design and the methods used to estimate MICs, and in values found for MIC, where MIC is the improvement in clinical status of an individual patient. However, after discussion among experts and workshop participants a reasonable consensus was achieved. Proposed MIC values are: 15 for the Visual Analogue Scale, 2 for the Numerical Rating Scale, 5 for the Roland Disability Questionnaire, 10 for the Oswestry Disability Index, and 20 for the QBDQ. When the baseline score is taken into account, a 30% improvement was considered a useful threshold for identifying clinically meaningful improvement on each of these measures. Conclusion. For a range of commonly used back pain outcome measures, a 30% change from baseline may be considered clinically meaningful improvement when comparing before and after measures for individual patients. It is hoped that these proposals facilitate the use of these measures in clinical practice and the comparability of future studies. The proposed MIC values are not the final answer but offer a common starting point for future research.

The burden and determinants of neck pain in the general population: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: STUDY DESIGN: Best evidence synthesis. OBJECTIVE: To undertake a best evidence synthesis of the published evidence on the burden and determinants of neck pain and its associated disorders in the general population. SUMMARY OF BACKGROUND DATA: The evidence on burden and determinants of neck has not previously been summarized. METHODS: The Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders performed a systematic search and critical review of literature published between 1980 and 2006 to assemble the best evidence on neck pain. Studies meeting criteria for scientific validity were included in a best evidence synthesis. RESULTS: We identified 469 studies on burden and determinants of neck pain, and judged 249 to be scientifically admissible; 101 articles related to the burden and determinants of neck pain in the general population. Incidence ranged from 0.055 per 1000 person years (disc herniation with radiculopathy) to 213 per 1000 persons (self-reported neck pain). Incidence of neck injuries during competitive sports ranged from 0.02 to 21 per 1000 exposures. The 12-month prevalence of pain typically ranged between 30% and 50%; the 12-month prevalence of activity-limiting pain was 1.7% to 11.5%. Neck pain was more prevalent among women and prevalence peaked in middle age. Risk factors for neck pain included genetics, poor psychological health, and exposure to tobacco. Disc degeneration was not identified as a risk factor. The use of sporting gear (helmets, face shields) to prevent other types of injury was not associated with increased neck injuries in bicycling, hockey, or skiing. CONCLUSION: Neck pain is common. Nonmodifiable risk factors for neck pain included age, gender, and genetics. Modifiable factors included smoking, exposure to tobacco, and psychological health. Disc degeneration was not identified as a risk factor. Future research should concentrate on longitudinal designs exploring preventive strategies and modifiable risk factors for neck pain. Language: en

Full-endoscopic interlaminar and transforaminal lumbar discectomy versus conventional microsurgical technique: a prospective, randomized, controlled study.

Abstract: Study design Prospective, randomized, controlled study of patients with lumbar disc herniations, operated either in a full-endoscopic or microsurgical technique. Objective Comparison of results of lumbar discectomies in full-endoscopic interlaminar and transforaminal technique with the conventional microsurgical technique. Summary of background data Even with good results, conventional disc operations may result in subsequent damage due to trauma. Endoscopic techniques have become the standard in many areas because of the advantages they offer intraoperatively and after surgery. With the transforaminal and interlaminar techniques, 2 full-endoscopic procedures are available for lumbar disc operations. Methods One hundred seventy-eight patients with full-endoscopic or microsurgical discectomy underwent follow-up for 2 years. In addition to general and specific parameters, the following measuring instruments were used: VAS, German version North American Spine Society Instrument, Oswestry Low-Back Pain Disability Questionnaire. Results After surgery 82% of the patients no longer had leg pain, and 14% had occasional pain. The clinical results were the same in both groups. The recurrence rate was 6.2% with no difference between the groups. The full-endoscopic techniques brought significant advantages in the following areas: back pain, rehabilitation, complications, and traumatization. Conclusion The clinical results of the full-endoscopic technique are equal to those of the microsurgical technique. At the same time, there are advantages in the operation technique and reduced traumatization. With the surgical devices and the possibility of selecting an interlaminar or posterolateral to lateral transforaminal procedure, lumbar disc herniations outside and inside the spinal canal can be sufficiently removed using the full-endoscopic technique, when taking the appropriate criteria into account. Full-endoscopic surgery is a sufficient and safe supplementation and alternative to microsurgical procedures.

Course and Prognostic Factors for Neck Pain in Whiplash-Associated Disorders (WAD) : Results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders

Abstract: STUDY DESIGN: Best evidence synthesis. OBJECTIVE: To perform a best evidence synthesis on the course and prognostic factors for neck pain and its associated disorders in Grades I-III whiplash-associated disorders (WAD). SUMMARY OF BACKGROUND DATA: Knowledge of the course of recovery of WAD guides expectations for recovery. Identifying prognostic factors assists in planning management and intervention strategies and effective compensation policies to decrease the burden of WAD. METHODS: The Bone and Joint Decade 2000-2010 Task Force on Neck Pain and its Associated Disorders (Neck Pain Task Force) conducted a critical review of the literature published between 1980 and 2006 to assemble the best evidence on neck pain and its associated disorders. Studies meeting criteria for scientific validity were included in a best evidence synthesis. RESULTS: We found 226 articles related to course and prognostic factors in neck pain and its associated disorders. After a critical review, 70 (31%) were accepted on scientific merit; 47 of these studies related to course and prognostic factors in WAD. The evidence suggests that approximately 50% of those with WAD will report neck pain symptoms 1 year after their injuries. Greater initial pain, more symptoms, and greater initial disability predicted slower recovery. Few factors related to the collision itself (for example, direction of the collision, headrest type) were prognostic; however, postinjury psychological factors such as passive coping style, depressed mood, and fear of movement were prognostic for slower or less complete recovery. There is also preliminary evidence that the prevailing compensation system is prognostic for recovery in WAD. CONCLUSION: The Neck Pain Task Force undertook a best evidence synthesis to establish a baseline of the current best evidence on the course and prognosis for WAD. Recovery of WAD seems to be multifactorial. Language: en

A consensus approach toward the standardization of back pain definitions for use in prevalence studies

Abstract: A modified Delphi study conducted with 28 experts in back pain research from 12 countries. OBJECTIVE. To identify standardized definitions of low back pain that could be consistently used by investigators in prevalence studies to provide comparable data. SUMMARY OF BACKGROUND DATA. Differences in the definition of back pain prevalence in population studies lead to heterogeneity in study findings, and limitations or impossibilities in comparing or summarizing prevalence figures from different studies. METHODS. Back pain definitions were identified from 51 articles reporting population-based prevalence studies, and dissected into 77 items documenting 7 elements. These items were submitted to a panel of experts for rating and reduction, in 3 rounds (participation: 76%). Preliminary results were presented and discussed during the Amsterdam Forum VIII for Primary Care Research on Low Back Pain, compared with scientific evidence and confirmed and fine-tuned by the panel in a fourth round and the preparation of the current article. RESULTS. Two definitions were agreed on a minimal definition (with 1 question covering site of low back pain, symptoms observed, and time frame of the measure, and a second question on severity of low back pain) and an optimal definition that is made from the minimal definition and add-ons (covering frequency and duration of symptoms, an additional measure of severity, sciatica, and exclusions) that can be adapted to different needs. CONCLUSION. These definitions provide standards that may improve future comparisons of low back pain prevalence figures by person, place and time characteristics, and offer opportunities for statistical summaries.

Surgical versus nonoperative treatment for lumbar disc herniation: four-year results for the Spine Patient Outcomes Research Trial (SPORT).

Abstract: Study design Concurrent prospective randomized and observational cohort studies. Objective To assess the 8-year outcomes of surgery versus nonoperative care. Summary of background data Although randomized trials have demonstrated small short-term differences in favor of surgery, long-term outcomes comparing surgical with nonoperative treatment remain controversial. Methods Surgical candidates with imaging-confirmed lumbar intervertebral disc herniation meeting Spine Patient Outcomes Research Trial eligibility criteria enrolled into prospective randomized (501 participants) and observational cohorts (743 participants) at 13 spine clinics in 11 US states. Interventions were standard open discectomy versus usual nonoperative care. Main outcome measures were changes from baseline in the SF-36 Bodily Pain and Physical Function scales and the modified Oswestry Disability Index-AAOS/Modems version assessed at 6 weeks, 3 months, and 6 months, and annually thereafter. Results Advantages were seen for surgery in intent-to-treat analyses for the randomized cohort for all primary and secondary outcomes other than work status; however, with extensive nonadherence to treatment assignment (49% patients assigned to nonoperative therapy receiving surgery versus 60% of patients assigned to surgery) these observed effects were relatively small and not statistically significant for primary outcomes (bodily pain, physical function, Oswestry Disability Index). Importantly, the overall comparison of secondary outcomes was significantly greater with surgery in the intent-to-treat analysis (sciatica bothersomeness [P > 0.005], satisfaction with symptoms [P > 0.013], and self-rated improvement [P > 0.013]) in long-term follow-up. An as-treated analysis showed significant surgical treatment effects for primary outcome measures (mean change, surgery vs. nonoperative care; treatment effect; 95% confidence interval): bodily pain (45.3 vs. 34.4; 10.9; 7.7 to 14); PF (42.2 vs. 31.5; 10.6; 7.7 to 13.5); and Oswestry Disability Index (-36.2 vs. -24.8; -11.3; -13.6 to -9.1). Conclusion Carefully selected patients who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients; there was little to no degradation of outcomes in either group (operative and nonoperative) from 4 to 8 years. Level of evidence 2.

Sciatica: review of epidemiological studies and prevalence estimates.

Abstract: Study design Review of studies on sciatica prevalence and synthesis of available evidence. Objective To assess the studies on sciatica prevalence, discuss reasons for variation in estimates, provide suggestions for improving accuracy of recording sciatica in epidemiological and outcome studies so as to enable better evaluation of natural history and treatment effect in the presence of low back pain related sciatica. Summary of background data Sciatica is a common cause of pain and disability. It is more persistent and severe than low back pain, has a less favorable outcome and consumes more health resources. However, sciatica prevalence rates reported in different studies and reviews vary considerably and provide no clear picture about sciatica prevalence. Methods A literature search of all English language peer reviewed publications was conducted using Medline, EMBASE, and CINAHL for the years 1980-2006. Two reviewers extracted data on sciatica prevalence and definitions from the identified articles. Results Of the papers retrieved, 23 were included in the review. Only 2 studies out of the 23 used clinical assessment for assessing sciatic symptoms, and definitions of sciatica varied widely. Sciatica prevalence from different studies ranged from 1.2% to 43%. Conclusion Sciatica prevalence estimates vary considerably between studies. This may be due to differences in definitions, methods of data collection and perhaps populations studied. Suggestions are made on how to improve accuracy of capturing sciatica in epidemiological studies.

Surgical Versus Nonoperative Treatment for Lumbar Disc Herniation

Abstract: Study Design.Concurrent, prospective, randomized, and observational cohort study.Objective.To assess the 4-year outcomes of surgery versus nonoperative care.Summary of Background Data.Although randomized trials have demonstrated small short-term differences in favor of surgery, long-term outcomes co

The burden and determinants of neck pain in workers: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: Study design Systematic review and best evidence synthesis. Objectives To describe the prevalence and incidence of neck pain and disability in workers; to identify risk factors for neck pain in workers; to propose an etiological diagram; and to make recommendations for future research. Summary of background data Previous reviews of the etiology of neck pain in workers relied on cross-sectional evidence. Recently published cohorts and randomized trials warrant a re-analysis of this body of research. Methods We systematically searched Medline for literature published from 1980-2006. Retrieved articles were reviewed for relevance. Relevant articles were critically appraised. Articles judged to have adequate internal validity were included in our best evidence synthesis. Results One hundred and nine papers on the burden and determinants of neck pain in workers were scientifically admissible. The annual prevalence of neck pain varied from 27.1% in Norway to 47.8% in Quebec, Canada. Each year, between 11% and 14.1% of workers were limited in their activities because of neck pain. Risk factors associated with neck pain in workers include age, previous musculoskeletal pain, high quantitative job demands, low social support at work, job insecurity, low physical capacity, poor computer workstation design and work posture, sedentary work position, repetitive work and precision work. We found preliminary evidence that gender, occupation, headaches, emotional problems, smoking, poor job satisfaction, awkward work postures, poor physical work environment, and workers' ethnicity may be associated with neck pain. There is evidence that interventions aimed at modifying workstations and worker posture are not effective in reducing the incidence of neck pain in workers. Conclusion Neck disorders are a significant source of pain and activity limitations in workers. Most neck pain results from complex relationships between individual and workplace risk factors. No prevention strategies have been shown to reduce the incidence of neck pain in workers.

Treatment of neck pain: noninvasive interventions: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: Study design Best evidence synthesis. Objective To identify, critically appraise, and synthesize literature from 1980 through 2006 on noninvasive interventions for neck pain and its associated disorders. Summary of background data No comprehensive systematic literature reviews have been published on interventions for neck pain and its associated disorders in the past decade. Methods We systematically searched Medline and screened for relevance literature published from 1980 through 2006 on the use, effectiveness, and safety of noninvasive interventions for neck pain and associated disorders. Consensus decisions were made about the scientific merit of each article; those judged to have adequate internal validity were included in our best evidence synthesis. Results Of the 359 invasive and noninvasive intervention articles deemed relevant, 170 (47%) were accepted as scientifically admissible, and 139 of these related to noninvasive interventions (including health care utilization, costs, and safety). For whiplash-associated disorders, there is evidence that educational videos, mobilization, and exercises appear more beneficial than usual care or physical modalities. For other neck pain, the evidence suggests that manual and supervised exercise interventions, low-level laser therapy, and perhaps acupuncture are more effective than no treatment, sham, or alternative interventions; however, none of the active treatments was clearly superior to any other in either the short- or long-term. For both whiplash-associated disorders and other neck pain without radicular symptoms, interventions that focused on regaining function as soon as possible are relatively more effective than interventions that do not have such a focus. Conclusion Our best evidence synthesis suggests that therapies involving manual therapy and exercise are more effective than alternative strategies for patients with neck pain; this was also true of therapies which include educational interventions addressing self-efficacy. Future efforts should focus on the study of noninvasive interventions for patients with radicular symptoms and on the design and evaluation of neck pain prevention strategies.

Proximal Junctional Kyphosis in Adult Spinal Deformity After Segmental Posterior Spinal Instrumentation and Fusion : Minimum Five-Year Follow-up

Abstract: Study Design. A retrospective study. Objective. To analyze time-dependent change of, prevalence of, and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity after long (≥5 vertebrae) segmental posterior spinal instrumented fusion with a minimum 5-year postoperative follow-up. of Background Data. No study has focused on time-dependent long-term proximal junctional change in adult spinal deformity after segmental posterior spinal instrumented fusion with minimum 5-year follow-up. Methods. Clinical and radiographic data of 161 (140 women/21 men) adult spinal deformity patients with minimum 5-year follow-up (average 7.8 years, range 5-19.8 years) treated with long posterior spinal instrumentation and fusion were analyzed. Radiographic measurements included sagittal Cobb angle at the proximal junction on preoperative, 8-weeks postoperation, 2-year postoperation, and ultimate follow-up (a5 years). Postoperative SRS outcome scores were also evaluated. Results. The prevalence of PJK at 7.8 years postoperation was 39% (62/161 patients). The PJK group (n = 62) demonstrated a significant increase in proximal junctional angle at 8 weeks (59%), between 2 years postoperation and ultimate postoperation (35%), and in thoracic kyphosis (T5-T12) at ultimate follow-up (P = 0.001). However, the sagittal vertical axis change at ultimate follow-up did not correlate with PJK (P = 0.53). Older age at surgery >55 years (vs. ≤55 years) and combined anterior and posterior spinal fusion (vs. posterior only) demonstrated significantly higher PJK prevalence (P = 0.001, 0.041, respectively). The SRS outcome scores did not demonstrate significant differences with the exception of the self-image domain when PJK exceeded 20°. Conclusion. The prevalence of PJK at 7.8 years postoperation was 39%. PJK progressed significantly within 8 weeks postoperation (59%) and between 2 years postoperation and ultimate follow-up (35%). Older age at surgery (>55 years) and combined anterior and posterior spinal fusion were identified as risk factors for developing PJK. The SRS outcome instrument was not adversely affected by PJK, except when PJK exceeded 20°.

Dual growing rod technique followed for three to eleven years until final fusion: the effect of frequency of lengthening.

Abstract: STUDY DESIGN Retrospective case review of children completing dual growing rod treatment at our institutions. Patients had a minimum of 2 years follow-up. OBJECTIVE To identify the factors influencing dual growing rod treatment outcome followed to final fusion. SUMMARY OF BACKGROUND DATA Published reports on dual growing rod technique results for early onset scoliosis demonstrate it to be safe and effective in curve correction and maintenance as well as in allowing spinal growth. METHODS Between 1990 and 2003, 13 patients with no previous surgery and noncongenital curves underwent final fusion. All had preoperative curve progression over 10 degrees after unsuccessful nonoperative treatment. There were 10 females and 3 males. Average age was 6.6 +/- 2.9 years at initial surgery. There were 3 idiopathic, 1 nonspine congenital anomaly, and 9 syndromic patients. Analysis included age at initial surgery and final fusion, number and frequency of lengthenings, and complications. Radiographic evaluation included changes in Cobb angle, T1-S1 length, and instrumentation length over the treatment period. RESULTS Cobb angle improved from 81.0 +/- 23 degrees to 35.8 +/- 15 degrees postinitial and 27.7 +/- 17 degrees after final fusion. Average number of lengthenings was 5.2 +/- 3 at an interval of 9.4 +/- 5 months. T1-S1 length increased from 24.4 +/- 3.4 to 29.3 +/- 3.6 cm postinitial and 35.0 +/- 3.7 cm postfinal fusion. Average growth was 1.46 +/- 0.66 cm/year. Those lengthened at

Standing balance and sagittal plane spinal deformity: analysis of spinopelvic and gravity line parameters.

Abstract: STUDY DESIGN Prospective study of 131 patients and volunteers recruited for an analysis of spinal alignment and gravity line (GL) assessment by force plate analysis. OBJECTIVE To determine relationships between GL, foot position, and spinopelvic landmarks in subjects with varying sagittal alignment. Additionally, the study sought to analyze the role of the pelvis in the maintenance of GL position. SUMMARY OF BACKGROUND DATA Force plate technology permits analysis of foot position and GL in relation to radiographically obtained landmarks. Previous investigation noted fixed GL-heel relationship across a wide age range despite changes in thoracic kyphosis. The pelvis as balance regulator has not been studied in the setting of sagittal spinal deformity. METHODS The 131 subjects were grouped by sagittal vertical axis (SVA) offset from the sacrum: sagittal forward (>2.5 cm), neutral (-2.5 cm

Course and prognostic factors for neck pain in the general population: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: STUDY DESIGN Best evidence synthesis. OBJECTIVE To undertake a best evidence synthesis on course and prognosis of neck pain and its associated disorders in the general population. SUMMARY OF BACKGROUND DATA Knowing the course of neck pain guides expectations for recovery. Identifying prognostic factors assists in planning public policies, formulating interventions, and promoting lifestyle changes to decrease the burden of neck pain. METHODS The Bone and Joint Decade 2000-2010 Task Force on Neck Pain and its Associated Disorders (Neck Pain Task Force) conducted a critical review of literature published between 1980 and 2006 to assemble the best evidence on neck pain. Findings from studies meeting criteria for scientific validity were abstracted into evidence tables and included in a best evidence synthesis. RESULTS We found 226 articles on the course and prognostic factors in neck pain and its associated disorders. After critical review, 70 (31%) of these were accepted on scientific merit. Six studies related to course and 7 to prognostic factors in the general population. Between half and three quarters of persons in these populations with current neck pain will report neck pain again 1 to 5 years later. Younger age predicted better outcome. General exercise was unassociated with outcome, although regular bicycling predicted poor outcome in 1 study. Psychosocial factors, including psychologic health, coping patterns, and need to socialize, were the strongest prognostic factors. Several potential prognostic factors have not been well studied, including degenerative changes, genetic factors, and compensation policies. CONCLUSION The Neck Pain Task Force undertook a best evidence synthesis to establish a baseline of the current best evidence on the course and prognosis for this symptom. General exercise was not prognostic of better outcome; however, several psychosocial factors were prognostic of outcome.

Lumbar adjacent segment degeneration and disease after arthrodesis and total disc arthroplasty.

Abstract: STUDY DESIGN: Systematic review of published incidence of radiographic adjacent segment degeneration (ASDeg) and symptomatic adjacent segment disease (ASDis) after arthrodesis or total disc replacement. OBJECTIVE: Assess impact of surgery method and other factors on the incidence of ASDeg and ASDis. SUMMARY OF BACKGROUND DATA: Twenty-seven articles, none of which were class I or II, met the inclusion criteria. Twenty involved arthrodesis (1732 patients) and 7 involved arthroplasty (758 patients). Nineteen detailed ASDeg and 16 detailed ASDis. METHODS: Data were established for number of patients, gender, average patient age, incidence of ASDeg and ASDis, average time to follow-up, and level and type of surgery. Multivariate logistic regression was used to identify which parameters had a significant effect on the incidence of ASDeg and ASDis. RESULTS: Three hundred fourteen of 926 patients in the arthrodesis group (34%) and 31 out of 313 patients in the total disc replacement group (9%) developed ASDeg. (P < 0.0001) Multivariate logistic regression indicated that higher odds of ASDeg were associated with: older patients (P < 0.001); arthodesis (P = 0.0008); and longer follow-up (P = 0.0025). For ASDis, 173/1216 (14%) arthrodesis patients developed ASDis compared to 7/595 (1%) of arthroplasty patients (P < 0.0001). Using multivariate logistic regression, higher odds of ASDis were seen in studies with fusion (P < 0.0001), higher percentages of male patients (P = 0.0019), and shorter follow-up (P < 0.05). CONCLUSION: Analysis of the literature suggests a correlation between fusion and the development of ASDeg compared to arthroplasty, but this association is dampened by the influence of patient age. There is a stronger correlation between fusion and ASDis compared to arthroplasty. The data supports only a class C recommendation (lowest tier) for the use of arthroplasty to reduce ASDis and disc degeneration compared to arthrodesis.

Full-endoscopic cervical posterior foraminotomy for the operation of lateral disc herniations using 5.9-mm endoscopes: a prospective, randomized, controlled study.

Abstract: Study design Prospective, randomized, controlled study of patients with lateral cervical disc herniations, operated either in a full-endoscopic posterior or conventional microsurgical anterior technique. Objective Comparison of results of cervical discectomies in full-endoscopic posterior foraminotomy technique with the conventional microsurgical anterior decompression and fusion. Summary of background data Anterior cervical decompression and fusion is the standard procedure for operation of cervical disc herniations with radicular arm pain. Mobility-preserving posterior foraminotomy is the most common alternative in the case of lateral localization of the pathology. Despite good clinical results, problems may arise due to traumatization of the access. Endoscopic techniques are considered standard in many areas, since they may offer advantages in surgical technique and rehabilitation. These days, all disc herniations of the lumbar spine can be operated in full-endoscopic technique. With the full-endoscopic posterior cervical foraminotomy a procedures is available for cervical disc operations. Methods One hundred and seventy-five patients with full-endoscopic posterior or microsurgical anterior cervical discectomy underwent follow-up for 2 years. In addition to general and specific parameters, the following measuring instruments were used: VAS, German version North American Spine Society Instrument, Hilibrand Criteria. Results After surgery 87.4% of the patients no longer had arm pain, and 9.2% had occasional pain. The clinical results were the same in both groups. There were no significant difference between the groups in the revision or complication rate. The full-endoscopic technique brought advantages in operation technique, preserving mobility, rehabilitation, and traumatization. Conclusion The recorded results show that the full-endoscopic posterior foraminotomy is a sufficient and safe supplement and alternative to conventional procedures when the indication criteria are fulfilled. At the same time, it offers the advantages of a minimally invasive intervention.

Percutaneous Lumbar Zygapophysial (Facet) Joint Neurotomy Using Radiofrequency Current, in the Management of Chronic Low Back Pain : A Randomized Double-Blind Trial

Abstract: STUDY DESIGN A randomized controlled study of percutaneous radiofrequency neurotomy was conducted in 40 patients with chronic low back pain (20 active and 20 controls). OBJECTIVE The aim of the study was to evaluate the possible beneficial effect of percutaneous radiofrequency zygapophysial joint neurotomy in reducing pain and physical impairment in patients with pain from the lumbar zygapophysial joints, selected after repeated diagnostic blocks. SUMMARY OF BACKGROUND DATA Facet or zygapophysial joint pain may be one of the causes of chronic low back pain and may be treated by a percutaneous radiofrequency denervation. Patients may possibly be identified by a positive diagnostic block. These blocks need to be repeated as false positive responses to single blocks occur.In all previous studies patients treated with radiofrequency denervation have been selected after single diagnostic blocks resulting in a varying degree of relief. METHODS All patients were examined by an orthopedic surgeon before and 6 months after the treatment (sham or active). Inclusion criteria were 3 separate positive facet blocks. Denervation was achieved by multiple lesions at each level in an effort to provide effective denervation. RESULTS The active treatment group showed statistically significant improvement not only in back and leg pain but also back and hip movement as well as the sacro-iliac joint test. Pre operative sensory deficit and weak or absent ankle reflex normalized (P < 0.01) and (P < 0.05), respectively. There was significant improvement in quality of life variables, global perception of improvement, and generalized pain.The improvement seen in the active group was significantly greater then that seen in the placebo group with regard to all the above-mentioned variables. None of our patients had any complication other than transient postoperative pain that was easily managed. CONCLUSION Our study indicates that radiofrequency facet denervation is not a placebo and could be used in the treatment of carefully selected patients with chronic low back pain.

Clinimetric testing of three self-report outcome measures for low back pain patients in Brazil: which one is the best?

Abstract: Study design Translation, cross-cultural adaptation, and clinimetric testing of self-report outcome measures. Objective The aims of this investigation were to perform the translation and cross-cultural adaptation of the Patient-Specific Functional Scale (PSFS) into Brazilian-Portuguese and to perform a head-to-head comparison of the clinimetric properties of the Brazilian-Portuguese versions of the PSFS, the Roland-Morris Disability Questionnaire (RMDQ) and the Functional Rating Index (FRI). Summary of background data To date, there is no Brazilian-Portuguese version of the PSFS available and no head-to-head comparison of the Brazilian-Portuguese versions of the PSFS, RMDQ, and FRI has been undertaken. Methods The PSFS was translated and adapted into Brazilian-Portuguese. The PSFS, the RMDQ, and the FRI were administered to 99 patients with low back pain to evaluate internal consistency, reproducibility, ceiling and floor effects, construct validity, internal and external responsiveness. To fully test the construct validity and external responsiveness of these measures, it was necessary to cross-culturally adapt the Pain Numerical Rating Scale and the Global Perceived Effect Scale. Results All measures demonstrated high levels of internal consistency (Cronbach's alpha range = 0.88-0.90) and reproducibility (Intraclass Correlation Coefficient 2,1 range = 0.85-0.94). High correlations among the disability-related measures were observed (Pearson's r ranging from 0.51 to 0.71). No ceiling or floor effects were detected. The PSFS was consistently more responsive than the other measures in both the internal responsiveness and external responsiveness analyses. Conclusion The results from this study demonstrate that the Brazilian-Portuguese versions of the RMDQ, the FRI and the PSFS have similar clinimetric properties to each other and to the original English versions. Of allthe measures tested in this study the PSFS seems the most responsive. These measures will enable international comparisons to be performed, and encourage researchers to include Portuguese speakers in their clinical trials.

A simple disc degeneration model induced by percutaneous needle puncture in the rat tail.

Abstract: Study design : We evaluated the degenerative changes to rat tail vertebral discs induced by percutaneous needle puncture, and we compared 2 puncture styles for the depth of needle puncture and the rate of disc degeneration. Objective : To develop a simple animal model of disc degeneration. Summary of background data : The study of biologically based treatments for degenerative disc disease depends largely on animal models. Annulus needle puncture in the lumbar spine inducing disc degeneration in rabbits has proven successful, but a similar method has not been evaluated in the tail discs of rats, even though it might produce a desirable model for disc repair studies. Methods : Two consecutive rat tail vertebral discs, proximal and distal to the eighth coccygeal vertebra, were randomized for injury and control. The disc selected for injury was punctured percutaneously using a 20-gauge needle with either full penetration or half penetration. The discs were harvested 1, 2, and 4 weeks later. Measurements included disc height on molybdenum target digital radiographs, biochemistry (water content, glycosaminoglycans, and hydroxyproline), and histology. Results : Needle punctures with full or half penetration caused significant disc space narrowing and progressive histologic changes of degeneration as early as 1 and 2 weeks after injury, respectively. Significant decrease in glycosaminoglycan content was observed at 4 weeks in the half-penetration puncture discs and at 2 and 4 weeks in discs punctured penetratively. Penetrative puncture resulted in a faster decrease in disc height, lower glycosaminoglycan content, and higher grades of histologic degeneration. The water and hydroxyproline content of the discs did not change appreciably. Conclusion : Tail disc percutaneous needle puncture is a simple method for inducing disc degeneration and the rate of degeneration is positively related to the depth of needle puncture. This model still has some limitations that should be taken into consideration when results of disc regeneration research in this model are interpreted and extrapolated to human.

A new concept for making decisions regarding the surgical approach for cervical ossification of the posterior longitudinal ligament: the K-line.

Abstract: STUDY DESIGN To report a new index, the K-line, for deciding the surgical approach for cervical ossification of the posterior longitudinal ligament (OPLL). OBJECTIVE To analyze the correlation between the K-line-based classification of cervical OPLL patients and their surgical outcome. SUMMARY OF BACKGROUND DATA Previous studies showed that kyphotic alignment of the cervical spine and a large OPLL are major factors causing poor surgical outcome after laminoplasty for cervical OPLL patients. However, no report has evaluated these 2 factors in 1 parameter. METHODS The K-line was defined as a line that connects the midpoints of the spinal canal at C2 and C7. Twenty-seven patients who had cervical OPLL and underwent posterior decompression surgery were classified into 2 groups according to their K-line classification. OPLL did not exceed the K-line in the K-line (+) group and did exceed it in the K-line (-) group. By intraoperative ultrasonography, we evaluated the posterior shift of the spinal cord after the posterior decompression procedure. The Japanese Orthopedic Association scores before surgery and 1 year after surgery were evaluated, and the recovery rate was calculated. RESULTS Eight patients were classified as K-line (-), and 19 patients were classified as K-line (+). The mean recovery rate was 13.9% in the K-line (-) group and 66.0% in the K-line (+) group (P < 0.01). Ultrasonography showed that the posterior shift of the spinal cord was insufficient in the K-line (-) group. CONCLUSION The present results demonstrate that a sufficient posterior shift of the spinal cord and neurologic improvement will not be obtained after posterior decompression surgery in the K-line (-) group. Our new index, the K-line, is a simple and practical tool for making decisions regarding the surgical approach for cervical OPLL patients.

Facet joint osteoarthritis and low back pain in the community-based population.

Abstract: Study design Cross-sectional study. Objective To evaluate the association between lumbar spine facet joint osteoarthritis (FJ OA) identified by multidetector computed tomography (CT) and low back pain (LBP) in the community-based Framingham Heart Study. Summary of background data The association between lumbar FJ OA and LBP remains unclear. Methods This study was an ancillary project to the Framingham Heart Study. A sample of 3529 participants of the Framingham Heart Study aged 40 to 80 underwent multidetector CT imaging to assess aortic calcification. One hundred eighty-eight individuals were consecutively enrolled in this ancillary study to assess radiographic features associated with LBP. LBP in the preceding 12 months was evaluated using a self-report questionnaire. FJ OA was evaluated on CT scans using a 4-grade scale. The association between FJ OA and LBP was examined used multiple logistic regression models, while adjusting for gender, age, and BMI. Results CT imaging revealed a high prevalence of FJ OA (59.6% of males and 66.7% of females). Prevalence of FJ OA increases with age. By decade, FJ OA was present in 24.0% of 70-years-olds. By spinal level the prevalence of FJ OA was: 15.1% at L2-L3, 30.6% at L3-L4, 45.1% at L4-L5, and 38.2% at L5-S1. In this community-based population, individuals with FJ OA at any spinal level showed no association with LBP. Conclusion There is a high prevalence of FJ OA in the community. Prevalence of FJ OA increases with age with the highest prevalence at the L4-L5 spinal level. At low spinal levels women have a higher prevalence of lumbar FJ OA than men. In the present study, we failed to find an association between FJ OA, identified by multidetector CT, at any spinal level and LBP in a community-based study population.

Comparison of animal discs used in disc research to human lumbar disc: axial compression mechanics and glycosaminoglycan content.

Abstract: Study design Experimental measurement and normalization of in vitro disc axial compression mechanics and glycosaminoglycan and water content for several animal species used in intervertebral disc research. Objective To compare normalized axial mechanical properties and glycosaminoglycan and water content from other species to those of the human disc to aid in selection and interpretation of results in animal disc studies. Summary of background data There is a lack of mechanical and biochemical comparative data from animal intervertebral discs with respect to the human disc. Methods Intervertebral disc axial mechanical properties, glycosaminoglycan, and water content were evaluated for 9 disc types in 7 mammalian species: the calf, pig, baboon, sheep, rabbit, rat and mouse lumbar, and the cow and rat tail. Disc area and height were used for calculation of the normalized mechanical parameters. Glycosaminoglycan content was normalized by dry weight. Results Many directly measured mechanical parameters varied by orders of magnitude. However, these parameters became comparable and often did not show significant differences after geometric normalization. Both glycosaminoglycan and water content revealed similarity across species. Conclusion Disc axial mechanics are very similar across animal species when normalizing by the geometric parameters of disc height and area. This suggests that the disc tissue material properties are largely conserved across animal species. These results provide a reference to compare disc axial mechanics and glycosaminoglycan and water composition of experimental animal models to the human lumbar disc, to aid in both selection and interpretation of experimental disc research.

Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study.

Abstract: STUDY DESIGN Population-based, case-control and case-crossover study. OBJECTIVE To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke. SUMMARY OF BACKGROUND DATA Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke. METHODS Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls. RESULTS There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged <45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke. CONCLUSION VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.

The cost effectiveness of surgical versus nonoperative treatment for lumbar disc herniation over two years: evidence from the Spine Patient Outcomes Research Trial (SPORT).

Abstract: Lumbar discectomy is the most common surgical procedure performed in the US for patients with back pain and leg symptoms due to intervertebral disc herniation (IDH) 1, Disc herniation most frequently occurs among persons between 33 and 55 years of age; however, rates of spine surgery in the Medicare population--those 65 and older--rose dramatically in the United States over the period 1992 through 2003, with total Medicare spending on lumbar discectomy/laminectomy estimated at $306 million.2. While recent clinical evidence shows a health benefit for those undergoing surgery,3,4 the cost-effectiveness of operative intervention compared with non-operative care remains poorly characterized. One study reported moderate cost-effectiveness for surgical treatment of IDH,5 but had several important limitations. First, cost and health outcome data came from different populations. Second, transitions between health states were not observed with prospectively collected data appropriate for estimating impact on quality-adjusted life years (QALYs), but were modeled using decision analysis. Third, the effect of surgery on worker productivity (i.e., indirect costs) was not addressed. The results from the Maine Lumbar Spine Study suggest that indirect costs are important to evaluate because, although spine surgery was associated with pain reduction, it was not associated with increased labor force participation.6 A recent Swedish study suggested that surgery for IDH may be cost-saving when lost productivity due to permanent disability is considered.7 To comprehensively address the economic value of surgery for treatment of IDH, the multicenter Spine Patient Outcomes Research Trial (SPORT), included patients with confirmed diagnosis of IDH and tracked the impact of treatment on QALYs using a validated instrument (EQ-5D), resource utilization, and indirect costs .8 Reports of the SPORT primary outcomes among 1,244 patients with IDH suggest that both surgically and non-operatively treated patients improve over time 3,4 In this paper, we report on the cost-effectiveness of surgery for IDH using SPORT two-year cost and outcomes data.

The burden and determinants of neck pain in whiplash-associated disorders after traffic collisions: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: Study design Best evidence synthesis. Objective To undertake a best evidence synthesis on the burden and determinants of whiplash-associated disorders (WAD) after traffic collisions. Summary of background data Previous best evidence synthesis on WAD has noted a lack of evidence regarding incidence of and risk factors for WAD. Therefore there was a warrant of a reanalyze of this body of research. Methods A systematic search of Medline was conducted. The reviewers looked for studies on neck pain and its associated disorders published 1980-2006. Each relevant study was independently and critically reviewed by rotating pairs of reviewers. Data from studies judged to have acceptable internal validity (scientifically admissible) were abstracted into evidence tables, and provide the body of the best evidence synthesis. Results The authors found 32 scientifically admissible studies related to the burden and determinants of WAD. In the Western world, visits to emergency rooms due to WAD have increased over the past 30 years. The annual cumulative incidence of WAD differed substantially between countries. They found that occupant seat position and collision impact direction were associated with WAD in one study. Eliminating insurance payments for pain and suffering were associated with a lower incidence of WAD injury claims in one study. Younger ages and being a female were both associated with filing claims or seeking care for WAD, although the evidence is not consistent. Preliminary evidence suggested that headrests/car seats, aimed to limiting head extension during rear-end collisions had a preventive effect on reporting WAD, especially in females. Conclusion WAD after traffic collisions affects many people. Despite many years of research, the evidence regarding risk factors for WAD is sparse but seems to include personal, societal, and environmental factors. More research including, well-defined studies with accurate denominators for calculating risk, and better consideration of confounding factors, are needed.

A new conceptual model of neck pain: linking onset, course, and care: the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

Abstract: STUDY DESIGN: Iterative discussion and consensus by a multidisciplinary task force scientific secretariat reviewing scientific evidence on neck pain and its associated disorders OBJECTIVE: To provide an integrated model for linking the epidemiology of neck pain with its management and consequences, and to help organize and interpret existing knowledge, and to highlight gaps in the current literature SUMMARY OF BACKGROUND DATA: The wide variability of scientific and clinical approaches to neck pain described in the literature requires a unified conceptual model for appropriate interpretation of the research evidence METHODS: The 12-member Scientific Secretariat of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders critically reviewed and eventually accepted as scientifically admissible a total of 552 scientific papers The group met face-to-face on 18 occasions and had frequent additional telephone conference meetings over a 6-year period to discuss and interpret this literature and to agree on a conceptual model, which would accommodate findings Models and definitions published in the scientific literature were discussed and repeatedly modified until the model and case definitions presented here were finally approved by the group RESULTS: Our new conceptual model is centered on the person with neck pain or who is at risk for neck pain Neck pain is viewed as an episodic occurrence over a lifetime with variable recovery between episodes The model outlines the options available to individuals who are dealing with neck pain, along with factors that determine options, choices, and consequences The short- and long-term impacts of neck pain are also considered Finally, the model includes a 5-axis classification of neck pain studies based on how subjects were recruited into each study CONCLUSION: The Scientific Secretariat found the conceptual model helpful in interpreting the available scientific evidence We believe it can assist people with neck pain, researchers, clinicians, and policy makers in framing their questions and decisions

Degeneration of sacroiliac joint after instrumented lumbar or lumbosacral fusion: a prospective cohort study over five-year follow-up.

Abstract: STUDY DESIGN A prospective cohort study. OBJECTIVE To determine the cause-effect relationship between fusion and sacroiliac joint (SIJ) degeneration after instrumented posterolateral lumbar or lumbosacral fusion. SUMMARY OF BACKGROUND DATA Adjacent segment degeneration following spinal fusion has attracted considerable attention. However, little attention has been paid to the SIJ, which is one of the adjacent joints. METHODS This study prospectively examined 37 patients, who underwent instrumented posterolateral lumbar/lumbosacral fusion from July 1997 to October 1998. Among them, 32 patients were included in this study and defined as the fusion group (male/female: 10/22, mean age: 64 years). The fusion group was divided into 2 subgroups according to the range of fusion. Group 1 had floating fusion (fusion to L5) and included 22 patients (male/female: 7/15, mean age: 65.6 years). Group 2 had fixed fusion (fusion to S1) and included 10 patients (male/female: 3/7, mean age: 60.5 years). Thirty-four age-matched normal individuals (male/female: 18/16, mean age: 64.5 years) were recruited as a control group. SIJ degeneration was assessed by confirming the absence of degeneration in the SIJ by computed tomography scans before surgery and 2 weeks after surgery. The SIJ was evaluated again by taking computed tomography scans at 1 year and 5 years after surgery. The incidence of SIJ degeneration was evaluated and compared (fusion group vs. control group; group 1 vs. group 2). The clinical outcomes were evaluated using the Visual Analog Scales (VAS) and Oswestry Disability Index (ODI) before surgery and at the final follow-up. RESULTS The incidence of SIJ degeneration in the fusion group was 75% (24/32), which was significantly higher than that of the control Group 38.2% (13/34) (P < 0.05). The incidence of SIJ degeneration (bilateral and unilateral) and bilateral SIJ degeneration was higher in group 2 than in group 1 (P = 0.028 and 0.04, respectively). The incidence of SIJ degeneration was not associated with the number of fusion segments. At the 5-year follow-up, the patients in groups 1 and 2 reported significant improvements in the VAS and ODI scores compared with the preoperative scores. However, there was no significant difference in the decrease in VAS and ODI scores between the 2 groups (P = 0.145 and 0.278, respectively). CONCLUSION Instrumented posterolateral lumbar/lumbosacral fusion can be a cause of SIJ degeneration. SIJ degeneration develops more often in patients undergoing lumbosacral fusion regardless of the number of fusion segments.

Early opioid prescription and subsequent disability among workers with back injuries: the Disability Risk Identification Study Cohort.

Abstract: Study design Prospective, population-based cohort study. Objective To examine whether prescription of opioids within 6 weeks of low back injury is associated with work disability at 1 year. Summary of background data Factors related to early medical treatment have been little investigated as possible risk factors for development of long-term work disability among workers with back injuries. We have previously shown that about 1 of 3 of workers receive an opioid prescription early after a low back injury, and a recent study suggested that such prescriptions may increase risk for subsequent disability. Methods We analyzed detailed data reflecting paid bills for opioids prescribed within 6 weeks of the first medical visit for a back injury among 1843 workers with lost work-time claims. Additional baseline measures included an injury severity rating from medical records, and demographic, psychosocial, pain, function, smoking, and alcohol measures from a worker survey conducted 18 days (median) after receipt of the back injury claim. Computerized database records of work disability 1 year after claim submission were obtained for the primary outcome measure. Results Nearly 14% (254 of 1843) of the sample were receiving work disability compensation at 1 year. More than one-third of the workers (630 of 1843) received an opioid prescription within 6 weeks, and 50.7% of these (319 of 630) were received at the first medical visit. After adjustment for pain, function, injury severity, and other baseline covariates, receipt of opioids for more than 7 days (odds ratio = 2.2; 95% confidence interval, 1.5-3.1) and receipt of more than 1 opioid prescription were associated significantly with work disability at 1 year. Conclusion Prescription of opioids for more than 7 days for workers with acute back injuries is a risk factor for long-term disability. Further research is needed to elucidate this association.

Percutaneous endoscopic approach for highly migrated intracanal disc herniations by foraminoplastic technique using rigid working channel endoscope.

Abstract: STUDY DESIGN: A retrospective analysis of 59 patients operated for excision of soft highly migrated intracanal lumbar disc herniations by percutaneous endoscopic foraminoplasty. OBJECTIVE: To describe a safe and effective percutaneous endoscopic technique for removal of migrated herniations and report the results on the basis of modified MacNab criteria. SUMMARY OF BACKGROUND DATA: Migrated herniations pose a great challenge even for experienced endoscopic surgeons. These herniations are hidden from the endoscopic view by anatomic barriers like hypertrophied facet, inferior pedicle and foraminal ligaments rendering percutaneous endoscopic transforaminal lumbar discectomy (PELD) by conventional approach, difficult with high failure rate. Foraminoplasty, which means enlargement of foramen by undercutting ventral part of superior-facet, upper border of inferior pedicle along with ablation of foraminal ligament, can help us to address this issue. METHODS: Fifty-nine patients with soft highly migrated herniations who underwent PELD with foraminoplasty under local anesthesia from January 2002 to June 2006 were analyzed retrospectively. Patients were evaluated by postoperative Visual Analog Scale for leg pain and Oswestry Disability Index scores. Outcomes were graded according to modified MacNab criteria. RESULTS: Mean follow-up was 25.4 months. Mean visual analog scale score for radicular pain improved from 8.01 to 1.56, and mean Oswestry disability Index improved from 61.6 to 10.76. Based on modified MacNab criteria, 91.4% of patients experienced satisfactory outcome. Three patients had persistent leg pain after surgery. One patient underwent a repeat-PELD on next day and the other after 1 month. Both were relieved of symptoms. Third patient was subjected to open discectomy after 25 weeks from the first operation and showed improvement. Two patients had recurrent herniation at same level after 6 months; 1 patient underwent repeat PELD, and the other underwent open discectomy. Both patients had good results. CONCLUSION: Foraminoplastic-PELD is safe and effective procedure for surgical treatment of soft migrated herniations. The results are comparable to results of open discectomy.

The effect of relative needle diameter in puncture and sham injection animal models of degeneration.

Abstract: Study Design Biomechanical study and literature review Objectives To quantify the acute effect of needle diameter on the in vitro mechanical properties of cadaver lumbar discs in the rat and sheep To review published in vivo animal studies and evaluate disc changes with respect to the relative needle size Summary of Background Data There are many cases where a disc needle puncture or injection is applied to animal models: puncture injuries to induce degeneration, chemonucleolysis to induce degeneration, and delivery of disc therapies It is not clear what role the size of the needle may have in the outcome Methods Mechanics were measured after sham phosphate buffered saline injection with a 27 G or 33 G needle in the rat and with a 27 G needle in the sheep A literature review was performed to evaluate studies in which animal discs were treated with a needle puncture or a sham injection For each study, the ratio of the needle diameter to disc height (needle:height) was calculated Results When the rat was injected with a 27 G needle (52% of disc height), the compression, tension, and neutral zone stiffnesses were 20% to 60% below preinjected values and the neutral zone length was 130% higher; when injected with a 33 G needle (26% of disc height), the only affected property was the neutral zone length, which was only 20% greater When the sheep was injected with a 27 G needle (10% of disc height), none of the axial properties were different from intact, the torsion stiffness was not different, and the torque range was 15% smaller Twenty-three in vivo studies in the rat, rabbit, dog, or sheep were reviewed The disc changes depended on the ratio of needle diameter to disc height as follows: significant changes were not observed for needle:height less than 40%, although between 25% and 40% results were variable and some minor nonsignificant effects were observed, disc changes were universal for needle:height over 40% Conclusion A needle puncture may directly alter mechanical properties via nucleus pulposus depressurization and/or anulus fibrosus damage, depending on the relative needle size As more basic science research is aimed at treating disc degeneration via injection of therapeutic factors, these findings provide guidance in design of animal studies Such studies should consider the relative needle size and include sham control groups to account for the potential effects of the needle injection