Are We Finally Ready for Total Joint Replacement of the Spine? An Extension of Charnley's Vision

Professor Sir John Charnley has been rightfully hailed as a visionary innovator for conceiving, designing, and validating the Operation of the Century-the total hip arthroplasty. His groundbreaking achievement forever changed the orthopedic management of chronically painful and dysfunctional arthritic joints. However, the well-accepted surgical approach of completely removing the diseased joint and replacing it with a durable and anatomically based implant never translated to the treatment of the degenerated spine. Instead, decompression coupled with fusion evolved into the workhorse intervention. In this commentary, the authors explore the reasons why arthrodesis has remained the mainstay over arthroplasty in the field of spine surgery as well as discuss the potential shift in the paradigm when it comes to treating degenerative lumbar disease.

In Vitro Wear of a Novel Vitamin E Crosslinked Polyethylene Lumbar Total Joint Replacement

BACKGROUND

A novel, lumbar total joint replacement (TJR) design has been developed to treat degeneration across all three columns of the lumbar spine (anterior, middle, and posterior columns). Thus far, there has been no in vitro studies that establish the preclinical safety profile of the vitamin E-stabilized highly crosslinked polyethylene (VE-HXLPE) lumbar TJR relative to historical lumbar anterior disc replacement for the known risks of wear and impingement faced by all motion preserving designs for the lumbar spine.

QUESTIONS/PURPOSE

In this study we asked, (1) what is the wear performance of the VE-HXLPE lumbar TJR under ideal, clean conditions? (2) Is the wear performance of VE-HXLPE in lumbar TJR sensitive to more aggressive, abrasive conditions? (3) How does the VE-HXLPE lumbar TJR perform under impingement conditions?

METHOD

A lumbar TJR with bilateral VE-HXLPE superior bearings and CoCr inferior bearings was evaluated under clean, impingement, and abrasive conditions. Clean and abrasive testing were guided by ISO 18192-1 and impingement was assessed as per ASTM F3295. For abrasive testing, CoCr components were scratched to simulate in vivo abrasion. The devices were tested for 10 million cycles (MC) under clean conditions, 5 MC under abrasion, and 1 MC under impingement.

RESULT

Wear rates under clean and abrasive conditions were 1.2 ± 0.5 and 1.1 ± 0.6 mg/MC, respectively. The VE-HXLPE components demonstrated evidence of burnishing and multidirectional microscratching consistent with microabrasive conditions with the cobalt chromium spherical counterfaces. Under impingement, the wear rates ranged between 1.7 ± 1.1 (smallest size) and 3.9 ± 1.1 mg/MC (largest size). No functional or mechanical failure was observed across any of the wear modes.

CONCLUSIONS

Overall, we found that that a VE-HXLPE-on-CoCr lumbar total joint replacement design met or exceeded the benchmarks established by traditional anterior disc replacements, with wear rates previously reported in the literature ranging between 1 and 15 mg/MC.

CLINICAL RELEVANCE

The potential clinical benefits of this novel TJR design, which avoids long-term facet complications through facet removal with a posterior approach, were found to be balanced by the in vitro tribological performance of the VE-HXLPE bearings. Our encouraging in vitro findings have supported initiating an FDA-regulated clinical trial for the design which is currently under way.

Impact of Cervical Disc Arthroplasty vs Anterior Cervical Discectomy and Fusion on Driving Disability: Post Hoc Analysis of a Randomized Controlled Trial With 10-Year Follow-Up

BACKGROUND

Driving an automobile requires the ability to turn the neck laterally. Anecdotally, patients with multilevel fusions often complain about restricted turning motion. The purpose of this study was to compare the effectiveness of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) on driving disability improvement at 10-year follow-up after a 2-level procedure.

METHODS

In the original randomized controlled trial, patients with cervical radiculopathy or myelopathy at 2 levels underwent CDA or ACDF. The driving disability question from the Neck Disability Index was rated from 0 to 5 years preoperatively and up to 10 years postoperatively. Severity of driving disability was categorized into "none" (score 0), "mild" (1 or 2), and "severe" (3, 4, or 5). Score and severity were compared between groups.

RESULTS

Out of 397 patients, 148 CDA and 118 ACDF patients had 10-year follow-up. Driving disability scores were not different between the groups preoperatively (CDA: 2.65; ACDF: 2.71, P = 0.699). Postoperatively, the scores in the CDA group were significantly lower than those in the ACDF group at 5 (0.60 vs 1.08, P ≤ 0.001) and 10 years (0.66 vs 1.07, P = 0.001). Mean score improvement in the CDA group was significantly greater than the ACDF group at 10-year follow-up (-1.94 vs -1.63, P = 0.003). The majority of patients reported severe driving disability (CDA: 56.9%, ACDF: 58.0%, P = 0.968) before surgery. After surgery, a greater proportion of patients in the CDA group had neck pain-free driving compared with the ACDF group at 5 (63.3% vs 41.8%, P < 0.001) and 10 years (61.8% vs 41.2%, P = 0.003).

CONCLUSION

In patients with cervical radiculopathy/myelopathy and 2-level disease, CDA provided greater improvements in driving disability as compared with ACDF at 10-year follow-up. This is the first report of its kind. This finding may be attributable to preservation of motion associated with CDA.

CLINICAL RELEVENCE

This study provides valuable information regarding the improvement of driving disability after both CDA and ACDF. It demonstrates that both procedures result in significant improvements, with CDA resulting in even better improvements than ACDF, up to 10 year follow-up.

LEVEL OF EVIDENCE: 3

Loading of the lumbar spine during transition from standing to sitting: effect of fusion versus motion preservation at L4-L5 and L5-S1

BACKGROUND CONTEXT

Transition from standing to sitting significantly decreases lumbar lordosis with the greatest lordosis-loss occurring at L4-S1. Fusing L4-S1 eliminates motion and thus the proximal mobile segments maybe recruited during transition from standing to sitting to compensate for the loss of L4-S1 mobility. This may subject proximal segments to supra-physiologic flexion loading.

PURPOSE

Assess effects of instrumented fusion versus motion preservation at L4-L5 and L5-S1 on lumbar spine loads and proximal segment motions during transition from standing to sitting.

STUDY DESIGN

Biomechanical study using human thoracolumbar spine specimens.

METHODS

A novel laboratory model was used to simulate lumbosacral alignment changes caused by a person's transition from standing to sitting in eight T10-sacrum spine specimens. The sacrum was tilted in the sagittal plane while constraining anterior-posterior translation of T10. Continuous loading-data and segmental motion-data were collected over a range of sacral slope values, which represented transition from standing to different sitting postures. We compared different constructs involving fusions and motion preserving prostheses across L4-S1.

RESULTS

After L4-S1 fusion, the sacrum could not be tilted as far posteriorly compared to the intact spine for the same applied moment (p<.001). For the same reduction in sacral slope, L4-S1 fusion induced 2.9 times the flexion moment in the lumbar spine and required 2.4 times the flexion motion of the proximal segments as the intact condition (p<.001). Conversely, motion preservation at L4-S1 restored lumbar spine loads and proximal segment motions to intact specimen levels during transition from standing to sitting.

CONCLUSIONS

In general, sitting requires lower lumbar segments to undergo flexion, thereby increasing load on the lumbar disks. L4-S1 fusion induced greater moments and increased flexion of proximal segments to attain a comparable seated posture. Motion preservation using a total joint replacement prosthesis at L4-S1 restored the lumbar spine loads and proximal segment motion to intact specimen levels during transition from standing to sitting.

CLINICAL SIGNIFICANCE

After L4-S1 fusion, increased proximal segment loading during sitting may cause discomfort in some patients and may lead to junctional breakdown over time. Preserving motion at L4-S1 may improve patient comfort and function during activities of daily living, and potentially decrease the need for adjacent level surgery.

Occurrence and clinical implications of heterotopic ossification after cervical disc arthroplasty with the Prestige LP Cervical Disc at 2 contiguous levels

OBJECTIVE

The authors sought to assess the impact of heterotopic ossification (HO) on clinical outcomes and angular range of motion (ROM) after cervical disc arthroplasty (CDA) performed with the Prestige LP Cervical Disc (Prestige LP disc) at 2 levels.

METHODS

HO was assessed and graded from 0 to IV for increasing severity on lateral neutral radiographs at each visit in 209 patients who underwent implantation of Prestige LP discs at 2 cervical levels in a clinical trial with extended 10-year follow-up. ROM was compared by using HO grade, and clinical outcomes were compared between HO subgroups (grade 0-II vs III/IV) based on HO severity at 2 and 10 years after surgery.

RESULTS

The grade III/IV HO incidence at either or both index levels was 24.2% (48/198) at 2 years and 39.0% (57/146) at 10 years. No statistical difference was found in overall success; neurological success; or Neck Disability Index (NDI), neck pain, arm pain, or SF-36 Physical Component Summary (PCS) scores between the HO subgroups (grade 0-II vs III/IV) at either 2 or 10 years. The cumulative rate of possible implant-related adverse events (AEs) was higher in patients having grade III/IV HO at 2 years (56.3%) and 10 years (47.8%) compared with those having grade 0-II HO at 2 years (24.4%) and 10 years (17.9%), specifically in 2 subcategories: spinal events and HOs reported by the investigators. No statistical difference was found between the HO subgroups in possible implant-related serious AEs or secondary surgeries at the index or adjacent levels. The average angular ROMs at index levels were lower in subjects with higher-grade HO at 2 and 10 years. The average ROMs at the superior level were 8.8°, 6.6°, 3.2°, and 0.3°, respectively, for the HO grade 0/I, II, III, and IV groups at 10 years, and 7.9°, 6.2°, 3.7°, and 0.6°, respectively, at the inferior level.

CONCLUSIONS

Radiographically severe (grade III or IV) HO after CDA with the Prestige LP disc at 2 levels did not significantly affect efficacy or safety outcomes (severe AEs or secondary surgeries). However, severe HO, particularly grade IV HO, significantly limited ROM, as expected.

One-Level Versus 2-Level Treatment With Cervical Disc Arthroplasty or Fusion: Outcomes Up to 7 Years

Background

Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) have been used to treat degenerative disc disease at single as well as multiple cervical levels. This study compares the safety and efficacy of 1-level versus 2-level CDA and ACDF.

Methods

In total, 545 and 397 patients with degenerative disc disease were studied in 1-level and 2-level Food and Drug Administration (FDA)-approved clinical trials, respectively: CDA (n = 280 and 209), ACDF (n = 265 and 188). Data from these studies were used to compare 1- versus 2-level procedures: the propensity score method was used to adjust for potential confounding effects, and adjusted mean outcome safety and efficacy scores at 2 and 7 years postsurgery were compared between 1-level and 2-level procedures within treatment type.

Results

One-level and 2-level procedures had similar rates of improvement in overall success and patient-reported outcomes scores for both CDA and ACDF. There were no statistical differences in rates of implant-related adverse events (AEs) or serious implant-related AEs between 1-level and 2-level CDA. The 7-year rate of implant-related AEs was higher for 2-level than 1-level ACDF (27.7% vs 18.9%, P ≤ .036), though the rates of serious implant-related AEs between ACDF groups did not differ significantly. Secondary surgery rates were not statistically different between 1-level and 2-level procedures (CDA or ACDF) at the index or adjacent levels at 2 or 7 years. Grade IV heterotopic ossification at 7 years was reported in 4.6% of 1-level CDA patients and 8.6%/7.3% at the superior/inferior levels, respectively, of 2-level CDA patients.

Conclusions

One- and 2-level CDA appear equally safe and effective in the treatment of cervical degenerative disc disease. Two-level ACDF appears to be as effective as 1-level ACDF but with a higher rate of some AEs at long-term follow-up.

Level of Evidence

2.

Clinical Trials

clinicaltrials.gov: NCT00667459, NCT00642876, and NCT00637156.

Two-level cervical disc arthroplasty versus anterior cervical discectomy and fusion: 10-year outcomes of a prospective, randomized investigational device exemption clinical trial

OBJECTIVE

The authors assessed the 10-year clinical safety and effectiveness of cervical disc arthroplasty (CDA) to treat degenerative cervical spine disease at 2 adjacent levels compared to anterior cervical discectomy and fusion (ACDF).

METHODS

A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted comparing the low-profile titanium ceramic composite-based Prestige LP Cervical Disc (n = 209) at two levels with ACDF (n = 188). Ten-year follow-up data from a postapproval study were available on 148 CDA and 118 ACDF patients and are reported here. Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative follow-up intervals for up to 10 years. The primary endpoint was overall success, a composite variable that included key safety and efficacy considerations. Ten-year follow-up rates were 86.0% for CDA and 84.9% for ACDF.

RESULTS

From 2 to 10 years, CDA demonstrated statistical superiority over ACDF for overall success, with rates at 10 years of 80.4% versus 62.2%, respectively (posterior probability of superiority [PPS] = 99.9%). Neck Disability Index (NDI) success was also superior, with rates at 10 years of 88.4% versus 76.5% (PPS = 99.5%), as was neurological success (92.6% vs 86.1%; PPS = 95.6%). Improvements from preoperative results in NDI and neck pain scores were consistently statistically superior for CDA compared to ACDF. All other study effectiveness measures were at least noninferior for CDA compared to ACDF through the 10-year follow-up period, including disc height. Mean angular ranges of motion at treated levels were maintained in the CDA group for up to 10 years. The rates of grade IV heterotopic ossification (HO) at the superior and inferior levels were 8.2% and 10.3%, respectively. The rate of severe HO (grade III or IV) did not increase significantly from 7 years (42.4%) to 10 years (39.0%). The CDA group had fewer serious (grade 3-4) implant-related or implant/surgical procedure-related adverse events (3.8% vs 8.1%; posterior mean 95% Bayesian credible interval [BCI] of the log hazard ratio [LHR] -0.92 [-1.88, -0.01]). The CDA group also had statistically fewer secondary surgical procedures at the index levels (4.7%) than the ACDF group (17.6%) (LHR [95% BCI] -1.39 [-2.15, -0.61]) as well as at adjacent levels (9.0% vs 17.9%).

CONCLUSIONS

The Prestige LP Cervical Disc, implanted at two adjacent levels, maintains improved clinical outcomes and segmental motion 10 years after surgery and is a safe and effective alternative to fusion.Clinical trial registration no.: NCT00637156 (clinicaltrials.gov).

Long-term clinical and radiographic outcomes of the Prestige LP artificial cervical disc replacement at 2 levels: results from a prospective randomized controlled clinical trial

OBJECTIVE The aim of this study was to assess long-term clinical safety and effectiveness in patients undergoing anterior cervical surgery using the Prestige LP artificial disc replacement (ADR) prosthesis to treat degenerative cervical spine disease at 2 adjacent levels compared with anterior cervical discectomy and fusion (ACDF). METHODS A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted at 30 US centers, comparing the low-profile titanium ceramic composite-based Prestige LP ADR (n = 209) at 2 levels with ACDF (n = 188). Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative intervals to 84 months. The primary end point was overall success, a composite variable that included key safety and efficacy considerations. RESULTS At 84 months, the Prestige LP ADR demonstrated statistical superiority over fusion for overall success (observed rate 78.6% vs 62.7%; posterior probability of superiority [PPS] = 99.8%), Neck Disability Index success (87.0% vs 75.6%; PPS = 99.3%), and neurological success (91.6% vs 82.1%; PPS = 99.0%). All other study effectiveness measures were at least noninferior for ADR compared with ACDF. There was no statistically significant difference in the overall rate of implant-related or implant/surgical procedure-related adverse events up to 84 months (26.6% and 27.7%, respectively). However, the Prestige LP group had fewer serious (Grade 3 or 4) implant- or implant/surgical procedure-related adverse events (3.2% vs 7.2%, log hazard ratio [LHR] and 95% Bayesian credible interval [95% BCI] -1.19 [-2.29 to -0.15]). Patients in the Prestige LP group also underwent statistically significantly fewer second surgical procedures at the index levels (4.2%) than the fusion group (14.7%) (LHR -1.29 [95% BCI -2.12 to -0.46]). Angular range of motion at superior- and inferior-treated levels on average was maintained in the Prestige LP ADR group to 84 months. CONCLUSIONS The low-profile artificial cervical disc in this study, Prestige LP, implanted at 2 adjacent levels, maintains improved clinical outcomes and segmental motion 84 months after surgery and is a safe and effective alternative to fusion. Clinical trial registration no.: NCT00637156 (clinicaltrials.gov).

Cervical disc arthroplasty with the Prestige LP disc versus anterior cervical discectomy and fusion, at 2 levels: results of a prospective, multicenter randomized controlled clinical trial at 24 months

OBJECTIVE The authors compared the efficacy and safety of arthroplasty using the Prestige LP cervical disc with those of anterior cervical discectomy and fusion (ACDF) for the treatment of degenerative disc disease (DDD) at 2 adjacent levels. METHODS Patients from 30 investigational sites were randomized to 1 of 2 groups: investigational patients (209) underwent arthroplasty using a Prestige LP artificial disc, and control patients (188) underwent ACDF with a cortical ring allograft and anterior cervical plate. Patients were evaluated preoperatively, intraoperatively, and at 1.5, 3, 6, 12, and 24 months postoperatively. Efficacy and safety outcomes were measured according to the Neck Disability Index (NDI), Numeric Rating Scales for neck and arm pain, 36-Item Short-Form Health Survey (SF-36), gait abnormality, disc height, range of motion (investigational) or fusion (control), adverse events (AEs), additional surgeries, and neurological status. Treatment was considered an overall success when all 4 of the following criteria were met: 1) NDI score improvement of ≥ 15 points over the preoperative score, 2) maintenance or improvement in neurological status compared with preoperatively, 3) no serious AE caused by the implant or by the implant and surgical procedure, and 4) no additional surgery (supplemental fixation, revision, or nonelective implant removal). Independent statisticians performed Bayesian statistical analyses. RESULTS The 24-month rates of overall success were 81.4% for the investigational group and 69.4% for the control group. The posterior mean for overall success in the investigational group exceeded that in the control group by 0.112 (95% highest posterior density interval = 0.023 to 0.201) with a posterior probability of 1 for noninferiority and 0.993 for superiority, demonstrating the superiority of the investigational group for overall success. Noninferiority of the investigational group was demonstrated for all individual components of overall success and individual effectiveness end points, except for the SF-36 Mental Component Summary. The investigational group was superior to the control group for NDI success. The proportion of patients experiencing any AE was 93.3% (195/209) in the investigational group and 92.0% (173/188) in the control group, which were not statistically different. The rate of patients who reported any serious AE (Grade 3 or 4) was significantly higher in the control group (90 [47.9%] of 188) than in the investigational group (72 [34.4%] of 209) with a posterior probability of superiority of 0.996. Radiographic success was achieved in 51.0% (100/196) of the investigational patients (maintenance of motion without evidence of bridging bone) and 82.1% (119/145) of the control patients (fusion). At 24 months, heterotopic ossification was identified in 27.8% (55/198) of the superior levels and 36.4% (72/198) of the inferior levels of investigational patients. CONCLUSIONS Arthroplasty with the Prestige LP cervical disc is as effective and safe as ACDF for the treatment of cervical DDD at 2 contiguous levels and is an alternative treatment for intractable radiculopathy or myelopathy at 2 adjacent levels. Clinical trial registration no.: NCT00637156 ( clinicaltrials.gov ).

Analysis of CT-based navigation system for pedicle screw placement

The incidence of pedicle screw breech varies based on anatomic location, body habitus, surgeon experience, spinal deformity, and surgical technique. Pedicle breeches have been reported to occur in up to 40% of screws. The purpose of this retrospective study was to compare the rates of revision of pedicle screw placement when using intraoperative C-arm vs O-arm (Medtronic, Memphis, Tennessee) assessment of pedicle screws. An economic analysis was also performed based on the estimated cost of pedicle screw revision. Four (1%) of 386 control patients required pedicle screw revision for a breeched pedicle screw not identified with intraoperative C-arm fluoroscopy. In the study group, none of the 331 patients returned to the operating room when O-arm was used to assess pedicle screw placement. Based on the 1% rate of returning to the operating room in the control group, the annual rate of cases nationwide requiring pedicle screw revision would be approximately 2300, with a cost of approximately $40,595,000.These results suggest that the use of intraoperative O-arm can reduce the need for revision of a breeched pedicle screw. This can potentially lead to a major cost savings.

Retrospective study of posterior cervical fusions with rhBMP-2

Posterior cervical decompression and fusion can be performed for various spinal conditions. Previous rates of pseudoarthrosis have been reported in up to 38% of patients. The use of bone morphogenic protein (BMP) has been approved for use in certain anterior lumbar interbody fusion techniques to decrease the incidence of pseudoarthrosis. Bone morphogenic protein in the anterior cervical spine carries a potential increased risk of airway complications; however, few data exist on the safety and efficacy of BMP in the posterior cervical spine. The purpose of this study was to evaluate fusion success, safety, and heterotopic bone formation using BMP in posterior cervical fusion.Twenty-nine patients who received posterior cervical fusion with BMP were followed for a minimum of 12 months. Computed tomography scans were obtained at a minimum of 12 months postoperatively to evaluate for solid arthrodesis and the presence of heterotopic bone formation. Patients' demographic data and adverse events were evaluated. All patients underwent posterior cervical decompression and instrumented fusion of at least 1 level between 2006 and 2008. Of 37 patients eligible for the study, 29 agreed to participate. Three (10.3%) of 29 patients developed pseudoarthrosis, as found on computed tomography scan. None of these went on to further surgery. No evidence existed of heterotopic bone formation outside of the lateral masses or bone growth over the spinal canal or neuroforamen. No adverse events were related to the use of BMP in this series of posterior cervical fusions. Bone morphogenic protein can be used safely in posterior cervical spine fusion, but additional larger studies are recommended. Even with the use of bone morphogenic protein, the possibility of pseudoarthrosis exists.

Comparison of vertebroplasty and balloon kyphoplasty for treatment of vertebral compression fractures: a meta-analysis of the literature

BACKGROUND CONTEXT

Previous investigators have reported on benefits and risks associated with vertebroplasty and kyphoplasty, but there are limited comparison data available. Additionally, much of the data is from retrospective studies and case series.

PURPOSE

The purpose of this study is to review the literature and perform a meta-analysis of pain relief and risk of complications associated with vertebroplasty versus kyphoplasty.

STUDY DESIGN

A meta-analysis of the literature on effectiveness of pain control and risk of complications after vertebroplasty versus balloon kyphoplasty. Outcomes measures include visual analog scale and complications.

METHODS

A comprehensive review of the literature was performed. All studies providing information on pain relief and complications were included. Preoperative, postoperative, and change in visual analog scale (VAS) scores were tabulated. Data were analyzed to identify if a significant improvement in the VAS score occurred. Changes in the VAS scores were compared for vertebroplasty and kyphoplasty to determine if there was a significant difference.

RESULTS

A total of 1,036 abstracts were identified. Of these, 168 studies met the inclusion criteria. Mean pre- and postoperative VAS scores for vertebroplasty were 8.36 and 2.68, respectively, with a mean change of 5.68 (p<.001). The mean pre- and postoperative VAS scores for kyphoplasty were 8.06 and 3.46, respectively, with a mean change of 4.60 (p<.001). There was statistically greater improvement found with vertebroplasty versus kyphoplasty (p<.001). The risk of new fracture was 17.9% with vertebroplasty versus 14.1% with kyphoplasty (p<.01). The risk of cement leak was 19.7% with vertebroplasty versus 7.0% with kyphoplasty (p<.001).

CONCLUSIONS

Both vertebroplasty and kyphoplasty provided significant improvement in VAS pain scores. Vertebroplasty had a significantly greater improvement in pain scores but also had statistically greater risk of cement leakage and new fracture.

Transforaminal lumbar interbody fusion: a retrospective study of long-term pain relief and fusion outcomes

No long-term studies exist on the effectiveness of transforaminal lumbar interbody fusion. This study sought to determine postoperative pain, disability, and fusion status of transforaminal lumbar interbody fusion patients after > or = 4 years to establish long-term outcomes. A retrospective analysis of 42 patients with minimum 4-year follow-up was conducted. Patients completed visual analog pain scale (VAS) and Oswestry functional capacity evaluation pre- and postoperatively. Statistically significant improvement was noted in VAS and Oswestry functional capacity evaluation scores. Transforaminal lumbar interbody fusion is effective in alleviating intractable back pain over an extended time period. Solid radiographic fusion is unnecessary for clinically successful outcomes.

Redundant publications in the orthopedic literature

Rates of redundant publications in the general surgery literature are approximately 14%. This article identifies the rate of redundant publications in the orthopedic literature. All original articles published during the year 2000 in The Journal of Bone and Joint Surgery (American Volume), Journal of Orthopaedic Trauma, Journal of Spinal Disorders, and Spine were searched using PubMed. Redundancy rate was 4 (3.15%) of 127 for The Journal of Bone and Joint Surgery (American volume), zero (0%) of 70 for Journal of Orthopaedic Trauma, 2 (2.90%) of 69 for Journal of Spinal Disorders, and 11 (3.12%) of 353 for Spine.

Questionnaire survey of spine surgeons on the use of methylprednisolone for acute spinal cord injury

STUDY DESIGN

A questionnaire survey.

OBJECTIVE

Estimate the use and justification of the steroid protocol for spinal cord injury (SCI) patients.

SUMMARY OF BACKGROUND DATA

There remains significant debate over clinical benefits and potential complications of the steroid protocol for SCI patients.

METHODS

A survey was sent to spine surgeons requesting information on 1) specialization, 2) trauma center affiliation, 3) use of steroid protocol, 4) justification of using steroid protocol, and 5) SCI volume.

RESULTS

Responses were received from 305 surgeons. Fourteen (4.6%) surgeons used steroids only if initiated before their consult, 262 (85.9%) would initiate if within the accepted 8-hour timeframe, 20 (6.6%) did not use steroids at all, and 9 (3.0%) used a different protocol. Justification for steroids use: 65 improved recovery, 64 institutional protocol, 110 medicolegal reasons, and 26 did not personally initiate steroids. Eighteen surgeons listed both clinical benefit and institutional protocol, and 22 others listed both institutional protocol and medicolegal reasons.

CONCLUSIONS

The majority (90.5%) of responding surgeons used the steroid protocol; however, only 24.1% used the steroid protocol due to a belief in improved clinical outcomes.

A comparison of outcomes of anterior cervical discectomy and fusion in patients with and without radicular symptoms

Anterior cervical discectomy and fusion (ACDF) is commonly performed for degenerative conditions of the cervical spine with good to excellent results. There is controversy over the use of ACDF for patients with axial neck pain alone. A retrospective review of 202 patients from two private practice orthopaedic spine surgeons following ACDF with 39-month mean follow-up was performed. Patients completed pain drawings, pre- and postoperative visual analog pain scales (VAS), Oswestry functional capacity evaluations (OSW), and a postoperative neck disability index. Forty-one patients had axial neck pain alone, and 161 had radicular pain with or without neck pain. There were significant improvements in VAS and OSW scores following surgery for the combined study population as well as the neck pain only and radicular pain groups (p < .01). ACDF can be effectively used for treatment of patients with axial neck pain without radicular symptoms.

A treatment and outcomes analysis of patients with coccydynia

BACKGROUND CONTEXT

Coccydynia is a painful condition of the terminal portion of the spine often resulting from direct trauma, childbirth or unknown etiology. This is a relatively rare condition with no universally accepted treatment protocol.

PURPOSE

To more clearly determine the optimal treatment for patients with coccydynia and to assess the outcomes after conservative and surgical therapy.

STUDY DESIGN

Retrospective review of outcomes of all patients presenting with symptoms of coccydynia during a 5-year period.

PATIENT SAMPLE

Thirty-two patients presented to an orthopedic spine surgeon during a 5-year period with symptoms of coccydynia.

OUTCOME MEASURES

Patients completed visual analog pain scales (VAS) and the Oswestry (OSW) functional capacity index.

METHODS

Of the 32 patients in the study, 4 (13%) were treated with nonsteroidal anti-inflammatory drugs (NSAIDs) alone, 17 (53%) were treated with NSAIDs followed by local injections and 11 (34%) underwent coccygectomy after failure of NSAIDs and local injections. Patients completed VAS and OSW forms. Pain drawings were also completed.

RESULTS

Patients undergoing surgery had significantly greater pretreatment VAS scores (8.3 vs 5.4, p=.002). Surgical patients also had greater OSW scores, but not significantly (36.6 vs 24.2, p=.223). Marked improvement was reported by 9 of 11 (82%) surgical patients. Three of 11 (27%) surgical patients developed wound infections and 1 (9%) wound dehiscence. All infections resolved following irrigation and debridement and a short course of oral antibiotics.

CONCLUSIONS

Patients with coccydynia should be managed conservatively when possible. Treatment should include NSAIDs and local steroid injections. Patients will often require repeat injections over time. Surgery can offer reasonable results for patients failing conservative treatment, but they should be warned of the high rate of infection.

Preliminary experience with a new surgical treatment for dysphagia due to anterior cervical osteophytes

A technique for surgical treatment of anterior cervical osteophytes is presented. A midline trough is created in the osteophytes using a burr under fluoroscopy down to the anterior cervical line. A rongeur is used to remove the remaining osteophytes while protecting the lateral soft tissues. Two patients presented with symptoms of progressive dysphagia secondary to anterior cervical osteophytes. Each underwent surgical ostectomy without complication after failing conservative treatment. This technique provides a safe, effective method to remove anterior cervical osteophytes.

Use of electrical bone stimulation in spinal fusion

Spinal fusion is commonly done to manage deformity, restore stability, and eliminate excessive motion at specific spinal levels. Pseudarthrosis limits the clinical success of spinal fusion. Three types of electrical stimulation, which is used to manage non-union in long bones, recently have been applied in an attempt to enhance the rate of spinal fusion. Direct current electrical stimulation is internal and thus eliminates dependence on patient compliance. Pulsed electromagnetic fields and capacitively coupled electrical stimulation are external techniques that require patient compliance but do not have the increased risk associated with implantable devices. Firm conclusions about efficacy are difficult to establish because of inconsistencies in both determining a reliable, reproducible end point for fusion and in incorporating the effect of patient parameters. Most data indicate a positive effect for use of direct current stimulation, but further studies are necessary to determine its appropriateness as an adjuvant to spinal fusion.

Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion

STUDY DESIGN

A biomechanical study was performed using cadaveric cervical spine specimens.

OBJECTIVE

To determine the effect of cervical spine fusion on adjacent-level intradiscal pressure.

SUMMARY OF BACKGROUND DATA

Clinical studies have reported that patients with spinal fusion are at greater risk of pathology and early disc degeneration at adjacent levels. It is hypothesized that eliminating motion at one level leads to hypermobility and increased forces at adjacent levels, thus increasing the rate of disc degeneration.

METHODS

Six cadaveric cervical spine specimens were tested. Specimens were stabilized at T1 and loaded at C3 to 20 degrees of flexion and 15 degrees of extension. Intradiscal pressures and segmental motion at C4-C5 and C6-C7 were recorded first on intact specimens, and then after anterior cervical plating at C5-C6. Changes in intradiscal pressure and segmental motion were calculated and statistically analyzed using a paired Student t test.

RESULTS

Intradiscal pressures were significantly increased during flexion at both adjacent levels. The pressure increased by 73.2% at C4-C5 (P = 0.002), and by 45.3% at C6-C7 (P = 0.006). Intradiscal pressures increased at both adjacent levels during extension, but not significantly. During flexion, segmental motion increased at both adjacent levels, with greater increases at C4-C5. During extension, segmental motion increased at both adjacent levels, with greater increases at C6-C7.

CONCLUSIONS

Clinical studies have reported increased rates of disc degeneration at levels adjacent to fusion. It is believed that eliminating motion through fusion shifts the load to the adjacent levels, causing earlier disc degeneration. This study has shown that significant increases in intradiscal pressure and segmental motion occur at levels adjacent to fusion during normal range of motion. These results may partially explain the mechanism of early disc degeneration at levels adjacent to cervical spine fusion.

Effect of spirituality on successful recovery from spinal surgery

BACKGROUND

Many patients believe prayer helps them recover from health problems. Benefits of spirituality on other illnesses and surgical procedures have been reported. It is unknown whether patients with strong spiritual beliefs have a greater propensity for successful recovery from spinal surgery.

METHODS

In this study, 188 patients having spinal surgery completed the visual analog pain scale (VAS) and the Oswestry functional capacity questionnaire (OSW) before and after operation, and the scores were used to assess surgical outcome. Degree of spirituality was assessed using the INSPIRIT survey.

RESULTS

Paired t test revealed significant improvements in both the VAS and OSW outcome measures. Linear regression analysis revealed no correlation between change in either VAS or OSW.

CONCLUSIONS

These results suggest that recovery from spinal surgery may be more dependent on proper patient selection and surgical technique than on patient spiritual beliefs.

Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion

STUDY DESIGN

A biomechanical study was performed using cadaveric cervical spine specimens.

OBJECTIVE

To determine the effect of cervical spine fusion on adjacent-level intradiscal pressure.

SUMMARY OF BACKGROUND DATA

Clinical studies have reported that patients with spinal fusion are at greater risk of pathology and early disc degeneration at adjacent levels. It is hypothesized that eliminating motion at one level leads to hypermobility and increased forces at adjacent levels, thus increasing the rate of disc degeneration.

METHODS

Six cadaveric cervical spine specimens were tested. Specimens were stabilized at T1 and loaded at C3 to 20 degrees of flexion and 15 degrees of extension. Intradiscal pressures and segmental motion at C4-C5 and C6-C7 were recorded first on intact specimens, and then after anterior cervical plating at C5-C6. Changes in intradiscal pressure and segmental motion were calculated and statistically analyzed using a paired Student t test.

RESULTS

Intradiscal pressures were significantly increased during flexion at both adjacent levels. The pressure increased by 73.2% at C4-C5 (P = 0.002), and by 45.3% at C6-C7 (P = 0.006). Intradiscal pressures increased at both adjacent levels during extension, but not significantly. During flexion, segmental motion increased at both adjacent levels, with greater increases at C4-C5. During extension, segmental motion increased at both adjacent levels, with greater increases at C6-C7.

CONCLUSIONS

Clinical studies have reported increased rates of disc degeneration at levels adjacent to fusion. It is believed that eliminating motion through fusion shifts the load to the adjacent levels, causing earlier disc degeneration. This study has shown that significant increases in intradiscal pressure and segmental motion occur at levels adjacent to fusion during normal range of motion. These results may partially explain the mechanism of early disc degeneration at levels adjacent to cervical spine fusion.

A modified technique for anterior multilevel cervical fusion

Anterior cervical fusion with interbody bone graft and anterior plating is commonly performed. Unfortunately, the plate has been reported to shield the graft from loading, thus reducing fusion rates. Interbody fusion cages have been effective in the lumbar spine and have gained acceptance in the cervical spine. Twenty-five patients underwent anterior cervical fusion with this modified technique. All patients received anterior diskectomy and corpectomy, placement of an interbody fusion cage packed with corpectomy bone, and application of an anterior cervical plate. Fusion was defined by radiographic evidence of trabecular bone bridging through the cage. No external bracing was used except soft collars as needed. Pre- and postoperative pain scales were completed and statistically analyzed using paired t tests. There were no cases of pseudoarthrosis or major neurological, vascular, or wound complications. There was one case of mild dysphagia that remained unresolved. Mean operative time was comparable to standard instrumented multilevel cervical fusion surgeries. Visual analogue pain scales were significantly improved following surgery. The advantages of using interbody cages with anterior plating include immediate stability and support, elimination of donor site pain from iliac crest bone autograft, and a decrease in pseudoarthrosis by halving the number of fusion surfaces.

Posterior extradural lumbar disk fragment

We present the unique case of a patient with a sequestered disk fragment posterior to the thecal sac producing symptoms of spinal stenosis with neurogenic claudication. The majority of sequestered disk fragments migrate in either a cranial or caudal direction. In only a few cases have disk fragments been identified posterior to the thecal sac. Our patient had a sudden onset of bilateral groin and anterior thigh pain. Magnetic resonance imaging showed relatively severe stenosis at L4-5 with mild disk bulging. Intraoperatively, a large posteriorly placed encapsulated mass of soft tissue was found compressing the posterior portion of the thecal sac. Patients with acute onset of symptoms of spinal stenosis should have herniated disk included in their differential diagnosis, even in the absence of imaging confirmation.

Imaging of the cervical spine and its role in clinical decision making

Thorough imaging of the cervical spine often requires more than one test. The many available options from which to choose can often lead to redundancy and confusion regarding the best test series. In an effort to make the process of choosing the most effective imaging series more efficient, we review the current literature on cervical imaging and, from the information gathered, construct a diagnostic imaging algorithm for evaluating the cervical spine.

Dysphagia caused by anterior cervical osteophytes: a case report

This 79-year-old man had a several-year history of dysphagia. On presentation, he spoke with difficulty but was not short of breath, and hemoptysis was present. A 17-mm osteophyte anterior to C3-C4 encroached on the posterior aspect of the oral pharynx and esophagus. The patient underwent C3-C6 anterior ostectomy; recovery was complete within 4 weeks.

Neuroimaging in low back pain

Patients commonly present to family physicians with low back pain. Because the majority of patients fully or partially recover within six weeks, imaging studies are generally not recommended in the first month of acute low back pain. Exceptions include patients with suspected cauda equina syndrome, infection, tumor, fracture, or progressive neurologic deficit. Patients who do not improve within one month should obtain magnetic resonance imaging if a herniated disc is suspected. Computed tomographic scanning is useful in demonstrating osseous structures and their relations to the neural canal, and for assessment of fractures. Bone scans can be used to determine the extent of metastatic disease throughout the skeletal system. All imaging results should be correlated with the patient's signs and symptoms because of the high rate of positive imaging findings in asymptomatic persons.

Vertebroplasty: a new treatment strategy for osteoporotic compression fractures

Vertebroplasty is a procedure in which bone cement is injected into a fractured vertebral body in an attempt to stabilize fractured segments and reduce pain. This procedure was originally used to treat spinal lesions caused by metastases and has recently been used to treat severe bone loss caused by osteoporosis. In this article, we review the current treatment for osteoporosis, introduce vertebroplasty with its associated efficacy and risks, and describe kyphoplasty.

Techniques for stimulating spinal fusion: efficacy of electricity, ultrasound, and biologic factors in achieving fusion

Many advancements have been made in an attempt to decrease the rate of pseudoarthrosis. Some of these have involved the actual fusion surgery. Fusions with internal fixation devices are able to more effectively eliminate motion during the healing process, thus leading to increased fusion rates. Electrical stimulation and ultrasound were initially developed to aid in fracture healing, but have shown to be efficacious in spinal fusion, as well. Biologic growth factors have long been known to control the bone growth process. These proteins have been identified and isolated for use in augmenting spinal fusion. The discovery of bone morphogenetic protein has great promise in significantly improving fusion rates over the use of either allograft or autograft.

Whiplash: a review of a commonly misunderstood injury

Whiplash injury is a relatively common occurrence, but its mechanism and optimal treatment remain poorly understood. It is estimated that the incidence of whiplash injury is approximately 4 per 1,000 persons. The most common radiographic findings include either preexisting degenerative changes or a slight flattening of the normal lordotic curvature of the cervical spine. Computed tomography and magnetic resonance imaging are generally reserved for cases of neurologic deficit, suspected disc or spinal cord damage, fracture, or ligamentous damage. Biomechanics studies have determined that after rear impact C6 is rotated back into extension before movement of the upper cervical vertebrae. Thus, the lower cervical vertebrae were in extension while the upper vertebrae were in a position of relative flexion, producing an S shape in the cervical spine. It is believed that this abnormal motion pattern might play a role in the development of whiplash injuries. Historically, a soft cervical collar has been used early after the injury in an attempt to restrict cervical range of motion and limit the chances of further injury. More recent studies report rest and restriction of motion to be detrimental and to slow the healing process.

Comparison of posterior and transforaminal approaches to lumbar interbody fusion

STUDY DESIGN

A study of the transforaminal lumbar interbody fusion and the posterior lumbar interbody fusion techniques was performed.

OBJECTIVES

To describe the transforaminal lumbar interbody fusion technique, and to compare operative data, including blood loss and operative time, with data from posterior lumbar interbody fusion technique.

SUMMARY OF BACKGROUND DATA

The evolution of posterior lumbar fusion combined with anterior interbody fusion has resulted in increased fusion rates as well as improved reductions and stability. The transforaminal lumbar interbody fusion technique pioneered by Harms and Jeszensky offers potential advantages and provides a surgical alternative to more traditional methods.

METHODS

In 13 consecutive months, two spinal surgeons performed 40 transforaminal lumbar interbody fusions and 34 posterior lumbar interbody fusion procedures. Data regarding blood loss, operative times, and length of hospital stay were recorded. These data were analyzed using analysis of variance to show any significant differences between the two techniques. To determine whether differences in measured variables were dependent on patient gender or number of levels fused, epsilon(chi2) analysis was used.

RESULTS

No significant differences were found between transforaminal and posterior lumbar interbody fusions in terms of blood loss, operative time, or duration of hospital stay when a single-level fusion was performed. Significantly less blood loss occurred when a two-level fusion was performed using the transforaminal approach instead of the posterior approach (P < 0.01). Differences in measured variables for the two procedures were independent of patient age, gender, and the number of levels fused. There were no complications with the transforaminal approach, but the posterior approach resulted in multiple complications.

CONCLUSIONS

In this comparison of patients receiving transforaminal lumbar interbody fusion versus posterior lumbar interbody fusion, no complications occurred with the transforaminal approach, whereas multiple complications were associated with the posterior approach. Similar operative times, blood loss, and duration of hospital stay were obtained in single-level fusions, but significantly less blood loss occurred with the transforaminal lumbar interbody approach in two-level fusions. The transforaminal procedure preserves the interspinous ligaments of the lumbar spine and preserves the contralateral laminar surface as an additional surface for bone graft. It may be performed at all lumbar levels because it avoids significant retraction of the dura and conus medullaris.

Predicting factors of successful recovery from lumbar spine surgery among workers' compensation patients

It is commonly believed that patients who are compensated for a work-related injury have less incentive to return to work. This study evaluated how various factors affected the outcomes of lumbar spine surgery in terms of pain relief, functional status, return to work, and general health. Eighty-seven workers' compensation patients had spinal fusion or microdiskectomy. Subjects were evaluated preoperatively and postoperatively using the Oswestry disability scale and the Visual Analog Scale for Pain. The type of surgery performed significantly affected patient outcomes, while such factors as gender, age, smoking, and litigation were insignificant. Microdiskectomy patients, for example, had greater reduction in pain and disability than did fusion patients (P < .01). Return-to-work status was negatively affected by fusion (P < .01). Overall, 55% of patients did return to work in some capacity, but the rate was 72% for microdiskectomy patients versus 43% for fusion patients. While outcomes significantly improved, postoperative scores remained severe. This did not correlate with return-to-work rates, suggesting that outcomes measures may not be effective.

Intraoperative loosening of Bagby and Kuslich cages during anterior lumbar interbody fusion

The Bagby and Kuslich (BAK) interbody fusion system has been shown to be a safe and effective method for obtaining solid fusion while maintaining lumbar lordosis. Although postoperative cage loosening has been reported, intraoperative cage loosening has not. The authors describe three cases in which BAK cages became loosened during operation. After the first BAK cage was inserted, it appeared to be well positioned and firmly seated; after placement of the second cage, however, the first cage was loose. Each of these cages was replaced without incident and appeared well placed on follow-up. It is crucial for the surgeon to verify that all cages are firmly seated before closure. This may reduce the incidence of postoperative cage migration.

Load-carrying capacity of the human cervical spine in compression is increased under a follower load

STUDY DESIGN

An experimental approach was used to test human cadaveric cervical spine specimens.

OBJECTIVE

To assess the response of the cervical spine to a compressive follower load applied along a path that approximates the tangent to the curve of the cervical spine.

SUMMARY OF BACKGROUND DATA

The compressive load on the human cervical spine is estimated to range from 120 to 1200 N during activities of daily living. Ex vivo experiments show it buckles at approximately 10 N. Differences between the estimated in vivo loads and the ex vivo load-carrying capacity have not been satisfactorily explained.

METHODS

A new experimental technique was developed for applying a compressive follower load of physiologic magnitudes up to 250 N. The experimental technique applied loads that minimized the internal shear forces and bending moments, loading the specimen in nearly pure compression.

RESULTS

A compressive vertical load applied in the neutral and forward-flexed postures caused large changes in cervical lordosis at small load magnitudes. The specimen collapsed in extension or flexion at a load of less than 40 N. In sharp contrast, the cervical spine supported a load of up to 250 N without damage or instability in both the sagittal and frontal planes when the load path was tangential to the spinal curve. The cervical spine was significantly less flexible under a compressive follower load compared with the hypermobility demonstrated under a compressive vertical load (P < 0.05).

CONCLUSION

The load-carrying capacity of the ligamentous cervical spine sharply increased under a compressive follower load. This experiment explains how a whole cervical spine can be lordotic and yet withstand the large compressive loads estimated in vivo without damage or instability.

Complications of the anterior retropharyngeal approach in cervical spine surgery: a technique and outcomes review

The retropharyngeal approach is used to avoid the risks and limitations of transmucosal surgery. The standard Smith-Robinson approach does not allow complete exposure of the C3 body/disk in patients requiring instrumentation of C3 or in patients with a short, thick neck. The anterior retropharyngeal approach provides additional exposure to the entire cervical spine in these patients. Our results in 14 cases show the anterior retropharyngeal approach to the upper and lower cervical spine to be an effective surgical technique in cases of upper cervical spine abnormalities and for multilevel abnormalities in patients with a short, thick neck. Although complications occurred as a result of the procedure, no permanent disorders were encountered. Adequate exposure to the entire cervical spine can be achieved without the high incidence of infection associated with the transoral approach.

Management of incidental durotomy without mandatory bed rest. A retrospective review of 20 cases

STUDY DESIGN

A retrospective review of 20 patients with incidental durotomy treated without mandatory bed rest.

OBJECTIVES

To determine whether patients with incidental durotomy can be treated effectively without multiple days of bed rest.

SUMMARY OF BACKGROUND DATA

Incidental durotomy can cause postural headaches, nausea, vomiting, dizziness, photophobia, tinnitus, and vertigo. These symptoms are believed to result from a decrease in cerebrospinal fluid pressure, leading to traction on the supporting structures of the brain. Traditional management includes bed rest for up to 7 days to eliminate traction and reduce hydrostatic pressure during the healing process.

METHODS

Twenty incidental durotomies were repaired intraoperatively with dural stitches and fibrin glue. Patients were allowed to ambulate according to the natural course after surgery without mandatory bed rest. Symptoms were monitored closely for 1 week, and long-term follow-up assessments were obtained at a minimum of 10 months.

RESULTS

Of the 20 patients in this study, 75% had no symptoms after repair of the incidental durotomy. Each of the dural tears was 1-3 mm in length. Two patients reported headache, two reported nausea, and one reported tinnitus; no patients experienced vomiting. One patient (5%) had stitch loosening requiring revision surgery. There were no additional serious complications.

CONCLUSIONS

This study has shown that the majority of patients with incidental durotomy can be treated effectively with dural stitches and fibrin glue. Patients can be permitted to ambulate immediately after surgery but should be cautioned to lay flat if they develop symptoms. This will reduce the costs related to the hospital stay and missed work.

The surgical treatment of far lateral L3-L4 and L4-L5 disc herniations. A modified technique and outcomes analysis of 25 patients

STUDY DESIGN

A retrospective review of 25 patients who underwent a modified surgical procedure for the treatment of far lateral disc herniation.

OBJECTIVES

To describe a modification of previous surgical techniques for the treatment of far lateral disc herniation and to review the outcomes in resolution of pain and improvement of functional status.

SUMMARY OF BACKGROUND DATA

Lumbar disc herniations that occur far lateral to the intervertebral facet result in spinal nerve compression at L3-L4 and L4-L5. Previous surgical techniques have resulted in an increased risk of instability or continued postoperative back pain.

METHODS

Twenty-five patients with far lateral disc herniation underwent surgery using an extreme lateral approach. There was no medial facetectomy or disruption of the pars interarticularis. The intertransverse ligament was released from the superior portion of the inferior transverse process, and the nerve was located before removal of the disc. Preoperative and postoperative visual analog pain scale and Oswestry functional status evaluation were reviewed along with complications to evaluate the efficacy of the surgery.

RESULTS

No serious complications were noted, although transient neuropathic pain was common and was theorized to be caused by manipulation of the dorsal root ganglion during surgery. This pain was usually resolved within 4 to 6 weeks. The mean preoperative and postoperative visual analog scale scores were 7.7 and 4.2, respectively. The mean preoperative and postoperative Oswestry scores were 50.7% and 34.7%, respectively. Both of these improvements were statistically significant (P < 0.01).

CONCLUSIONS

This far lateral approach allowed the nerve and far lateral disc herniations to be easily identified. Also, there was less blood loss and no medial facetectomy or disruption of the pars interarticularis. This is a safe, effective technique with no disruption of spinal stability.

Adjacent-segment degeneration after lumbar fusion: a review of clinical, biomechanical, and radiologic studies

Lumbar fusion is commonly performed to relieve pain from degenerative conditions, including spinal stenosis and spondylolisthesis. While clinical studies have reported favorable fusion rates with limited complications, few have investigated the effect of fusion on the adjacent motion segment. A solid fusion alters the biomechanics at the adjacent level, resulting in increased mechanical demands. There have been reports of increased rates of adjacent-level pathologic lesions after fusion, but these have not accounted for the natural history of degenerative changes. Biomechanical and radiographic studies have shown increased forces, mobility, and intradiscal pressure in adjacent segments after fusion. It has been hypothesized that these changes lead to an acceleration in pathologic changes.

Traumatic L5-S1 spondylolisthesis

We report a case of traumatic spondylolisthesis in a 31-year-old man struck by a steel I-beam. Although most reported traumatic spondylolisthesis cases are from low-energy trauma, this was a high-energy trauma case. The initial examination revealed no signs of cauda equina syndrome, and the patient's spinal injury was primarily capsuloligamentous. We present this rare case, with a review of pertinent literature and treatment mechanisms for traumatic spondylolisthesis.

Low postoperative infection rates with instrumented lumbar fusion

BACKGROUND

Studies have shown postoperative infection rates increase with the use of internal instrumentation. It is believed that longer operative times, prolonged retraction, instrumentation, and bone grafting lead to a higher risk of infection.

METHODS

We retrospectively reviewed 126 consecutive instrumented lumbar fusions. All had bone graft. The infection rate was statistically compared with previously reported values.

RESULTS

Our infection rate (0.8%) was lower than the combined data from the literature (2.8%), though not significantly different. No significant differences were noted regarding patient or surgical factors.

CONCLUSIONS

This review showed that low rates of postoperative infection can be achieved despite patient or surgical factors. We believe that conforming to strict techniques, including copious irrigation and debridement, and having experienced operating room personnel and short operating times will reduce the incidence of postoperative infections.

Reliability of magnetic resonance imaging in predicting disc material posterior to the posterior longitudinal ligament in the cervical spine. A prospective study

STUDY DESIGN

This was a prospective study to evaluate the accuracy of magnetic resonance imaging in predicting the presence of disc material posterior to the posterior longitudinal ligament (PLL), compared with the accuracy of intraoperative visual and tactile examination of the PLL.

OBJECTIVES

To determine the accuracy of magnetic resonance imaging in predicting the presence of disc material posterior to the PLL.

SUMMARY OF BACKGROUND DATA

Whether removal of the disc to the PLL is sufficient when performing an anterior cervical discectomy and fusion or it is necessary to explore the spinal canal by taking down the PLL is controversial.

METHODS

Fifty-four cervical levels were examined by magnetic resonance imaging before surgery to determine whether there was disc material posterior to the PLL. During surgery, the PLL was examined and probed for disruption. The ligament was taken down, and free fragments were identified and removed.

RESULTS

Of 54 levels, 12 were correctly identified by magnetic resonance imaging as having disc material posterior to the PLL, and 26 were correctly identified as not having disc material posterior to the PLL. Surgery confirmed that at 26 levels there was disc material posterior to the PLL. Of these 26, 23 (88.5%) had visual or palpable disruption of the PLL. Magnetic resonance imaging failed to predict disc material posterior to the PLL in 14 of the cases in which its presence was confirmed during surgery. Magnetic resonance imaging had 46.2% sensitivity and 92.9% specificity rates.

CONCLUSIONS

Because of low sensitivity, magnetic resonance imaging should be used cautiously for predicting free disc material posterior to the PLL. Visual or palpable examination of the PLL during surgery is more accurate for this prediction.

The natural history of the cervical foramen in symptomatic and asymptomatic individuals aged 20-60 years as measured by magnetic resonance imaging. A descriptive approach

STUDY DESIGN

This study was intended to identify normal degenerative morphologic evolution in the bony foramen in asymptomatic subjects by decade in comparison with symptomatic subjects of like decades.

OBJECTIVES

To determine normal degenerative changes in the cervical spine caused by the aging process that predispose a person to foraminal stenosis and radiculopathy.

SUMMARY OF BACKGROUND DATA

Cervical radiculopathy is a common problem caused by degenerative changes as people age. The characteristics of the foramen that result in stenosis are not known.

METHODS

Five to six symptomatic and asymptomatic people in each decade volunteered for magnetic resonance imaging. Lordosis, disc heights, and ratio of spinal cord diameter to spinal canal diameter were measured at C4-C5, C5-C6, and C6-C7 from sagittal magnetic resonance images. Foraminal heights, widths, and areas were measured at the isthmus of the same foramen from oblique images.

RESULTS

Foraminal heights, widths, and areas were larger in asymptomatic patients than in symptomatic patients. Morphologic analysis showed that inferior facet hypertrophy tended to decrease the width of the foramen in aging people. Disc heights, lordosis, and ratio of spinal cord diameter to spinal canal diameter showed no significant differences.

CONCLUSIONS

Foraminal height affects overall foraminal area but tends to change little with age. Width also affects overall area and not only decreases in older people but also significantly affects the available area for the exiting nerve root.

Cervical epidural steroid injection with intrinsic spinal cord damage. Two case reports

STUDY DESIGN

Intrinsic cervical spinal cord damage represents the serious and permanent complications that can occur if cervical epidural steroid injections are administered while the patient is sedated. Two case reports are presented.

OBJECTIVES

To draw attention to the dangerous consequences that can arise from sedating a patient before administering a cervical epidural steroid injection.

SUMMARY OF BACKGROUND DATA

Reported complications of cervical epidural steroid injections have been minor and infrequent. No reports of intrinsic cervical cord damage could be found in a comprehensive English language literature search.

METHODS

Two case reports of permanent intrinsic cervical cord damage in patients who had been administered cervical epidural steroid injections while under intravenous sedation are presented. Magnetic resonance imaging was performed before and after the administration of cervical epidural steroid injections. Each patient had herniated nucleus pulposus before they received cervical epidural steroid injections and intrinsic cord damage on postinjection magnetic resonance images.

RESULTS

Both patients developed increased pain and neurologic symptoms within 24 hours of injection. To date, these symptoms appear to be permanent. However, Patient 1 had pain relief in her right arm and shoulder after undergoing a microdiscectomy, but pain was still persistent in her left leg, and she has developed a positive Lhermitte's sign.

CONCLUSION

These case reports indicate fluoroscopic guidance will not insure or prevent intrathecal perforation or spinal cord penetration during the administration of cervical epidural steroid injections. In addition, although intravenous sedations during cervical epidural steroid injections have been used numerous times without reported complications, it appears intravenous sedation in these two cases resulted in the inability of the patient to experience the expected pain and paresthesias at the time of spinal cord irritation. Therefore, the authors conclude that the patient should be fully awake during the administration of cervical epidural steroid injections, with only local anesthetic in the skin used for analgesia.

Flexion and traction effect on C5-C6 foraminal space

OBJECTIVE

To determine the effects of cervical flexion and traction on foraminal volume and isthmus area at the C5-C6 foraminal space in cadavers.

DESIGN

This study evaluated the foraminal space at C5-C6 in cadaver specimens during flexion and traction of the cervical spine.

SETTING

An orthopedic biomechanics laboratory and department of radiology of a university medical center.

PATIENTS OR OTHER PARTICIPANTS

Nine cadaver cervical spines, C1 through T3, were used in the study. Superficial tissues were dissected, preserving the ligaments.

INTERVENTIONS

Proximal and distal portions of the cadaver spines were potted using bone cement. Spines were mounted and imaged with computed tomography in neutral position, 15 degrees of flexion, and maximum flexion with and without 25lbs of axial traction.

MAIN OUTCOME MEASURES

The areas and volumes of the foramen were measured and calculated.

RESULTS

Flexion alone significantly increased the foraminal volume and isthmus area at C5-C6. Traction resulted in little additional change.

CONCLUSIONS

For cervical spines with mild to moderate degenerative changes at C5-C6, cervical flexion with or without traction produces significant increases in foraminal volume and area at the foraminal isthmus.

Effects of introspecting about reasons: inferring attitudes from accessible thoughts

Previous research has shown that analyzing reasons can change people's attitudes, but the exact mechanisms of this effect have not been entirely clear. It was hypothesized that introspecting about reasons focuses people's attention on thoughts that are accessible in memory and increases the extent to which people view their accessible thoughts as applicable to their current attitudes. In Study 1, college students formed initial impressions of a target person, and then positive or negative thoughts about the target person were made memorable. After a delay, half of the participants analyzed reasons for their attitude and half recalled the target person's behaviors. As predicted, people who analyzed reasons reported attitudes toward the target person that were based more on what they could recall about her. Study 2 showed that this effect occurs regardless of whether people initially form an online impression. Implications for the effects of analyzing reasons and for attitude formation are discussed.

Effects of introspecting about reasons: inferring attitudes from accessible thoughts

Previous research has shown that analyzing reasons can change people's attitudes, but the exact mechanisms of this effect have not been entirely clear. It was hypothesized that introspecting about reasons focuses people's attention on thoughts that are accessible in memory and increases the extent to which people view their accessible thoughts as applicable to their current attitudes. In Study 1, college students formed initial impressions of a target person, and then positive or negative thoughts about the target person were made memorable. After a delay, half of the participants analyzed reasons for their attitude and half recalled the target person's behaviors. As predicted, people who analyzed reasons reported attitudes toward the target person that were based more on what they could recall about her. Study 2 showed that this effect occurs regardless of whether people initially form an online impression. Implications for the effects of analyzing reasons and for attitude formation are discussed.

Extradural synovial thoracic cyst

SUMMARY OF BACKGROUND DATA. Case studies documenting the incidence of thoracic intraspinal, extradural synovial cysts are limited. The occurrence of synovial cysts is associated with varied symptoms that differ among cervical, thoracic, and lumbar regions. The clinical appearance may be similar to other spinal diseases. METHODS. This report describes symptoms exhibited by and care provided for a patient with extradural synovial thoracic cyst.