Characterization of opioid consumption and disposal patterns after total knee arthroplasty

Aims

The aim of this study was to determine the general postoperative opioid consumption and rate of appropriate disposal of excess opioid prescriptions in patients undergoing primary unilateral total knee arthroplasty (TKA).

Patients and Methods

In total, 112 patients undergoing surgery with one of eight arthroplasty surgeons at a single specialty hospital were prospectively enrolled. Three patients were excluded for undergoing secondary procedures within six weeks. Daily pain levels and opioid consumption, quantity, and disposal patterns for leftover medications were collected for six weeks following surgery using a text-messaging platform.

Results

Overall, 103 of 109 patients (94.5%) completed the daily short message service (SMS) surveys. The mean oral morphine equivalents (OME) consumed during the six weeks post-surgery were 639.6 mg (sd 323.7; 20 to 1616) corresponding to 85.3 tablets of 5 mg oxycodone per patient. A total of 66 patients (64.1%) had stopped taking opioids within six weeks of surgery and had the mean equivalent of 18 oxycodone 5 mg tablets remaining. Only 17 patients (25.7%) appropriately disposed of leftover medications.

Conclusion

These prospectively collected data provide a benchmark for general opioid consumption after uncomplicated primary unilateral TKA. Many patients are prescribed more opioids than they require, and leftover medication is infrequently disposed of appropriately, which increases the risk for illicit diversion. Cite this article: Bone Joint J 2019;101-B(7 Supple C):98–103

Ultrafast Formation of a Fermi-Dirac Distributed Electron Gas

Time- and angle-resolved photoelectron spectroscopy with 13 fs temporal resolution is used to follow the different stages in the formation of a Fermi-Dirac distributed electron gas in graphite after absorption of an intense 7 fs laser pulse. Within the first 50 fs after excitation, a sequence of time frames is resolved that are characterized by different energy and momentum exchange processes among the involved photonic, electronic, and phononic degrees of freedom. The results reveal experimentally the complexity of the transition from a nascent nonthermal towards a thermal electron distribution due to the different timescales associated with the involved interaction processes.

Thromboprophylaxis in patients with acute spinal injuries: an evidence-based analysis

BACKGROUND

The increased risk for venous thromboembolic events following spinal trauma is well established. The purpose of the present study was to examine the literature in order to determine the optimum thromboprophylaxis regimen for patients with acute spinal injuries with or without spinal cord injury.

METHODS

EMBASE, MEDLINE, and Cochrane databases were searched from the earliest available date to April 2008 for clinical trials comparing different methods of thromboprophylaxis in adult patients following acute spinal injuries (with or without spinal cord injury). Outcome measures included the prevalences of deep-vein thrombosis and pulmonary embolism and treatment-related adverse events.

RESULTS

The search yielded 489 studies, but only twenty-one of them fulfilled the inclusion criteria. The prevalence of deep-vein thrombosis was significantly lower in patients without spinal cord injury as compared with patients with spinal cord injury (odds ratio = 6.0; 95% confidence interval = 2.9 to 12.7). Patients with an acute spinal cord injury who were receiving oral anticoagulants had significantly fewer episodes of pulmonary embolism (odds ratio = 0.1; 95% confidence interval = 0.01 to 0.63) than those who were not receiving oral anticoagulants (either untreated controls or patients managed with low-molecular-weight heparin). The start of thromboprophylaxis within the first two weeks after the injury resulted in significantly fewer deep-vein-thrombosis events than delayed initiation did (odds ratio = 0.2; 95% confidence interval = 0.1 to 0.4). With regard to heparin-based pharmacoprophylaxis in patients with spinal trauma, low-molecular-weight heparin significantly reduced the rates of deep-vein thrombosis and bleeding episodes in comparison with the findings in patients who received unfractionated heparin, with odds ratios of 2.6 (95% confidence interval = 1.2 to 5.6) and 7.5 (95% confidence interval = 1.0 to 58.4) for deep-vein thrombosis and bleeding, respectively.

CONCLUSIONS

The prevalence of deep-vein thrombosis following a spine injury is higher among patients who have a spinal cord injury than among those who do not have a spinal cord injury. Therefore, thromboprophylaxis in these patients should start as early as possible once it is deemed safe in terms of potential bleeding complications. Within this population, low-molecular-weight heparin is more effective for the prevention of deep-vein thrombosis, with fewer bleeding complications, than unfractionated heparin is. The use of vitamin K antagonists appeared to be effective for the prevention of pulmonary embolism.

Spinal injuries after falls from hunting tree stands

BACKGROUND CONTEXT

Spinal injuries are common sequelae of falls from hunting tree stands. Significant neurological injury is not uncommon and can result in significant morbidity as well as enormous expenditure of health care dollars. Recent literature on the subject is limited.

PURPOSE

The purpose of this study was to identify precipitating causes, characterize the spectrum of spinal injury, and determine potential interventional safety and prevention recommendations.

STUDY DESIGN

A retrospective study.

METHODS

Medical record review of 22 patients admitted either directly or via referral to a level I spinal cord injury referral center over a 10-year period (1995-2005) after a fall from a hunting tree stand.

RESULTS

All patients were men with a mean age of 46 years (range, 27-80 years). Initial acute care hospitalization averaged 10 days (range, 2-28 days). The average height of fall was 18 feet (range, 10-30 feet). Four of 19 falls (21%) occurred during the morning hours, 2 of 19 falls occurred during the afternoon, and 13 of 19 falls (68%) occurred during the evening hours. Time lapse from injury to presentation to an emergency department ranged from 30 minutes to 14 hours. Alcohol use was a factor in 2 of 20 falls (10%). Hypothermia complicated 3 of 21 cases (14%). Associated injuries were present in 12 of 21 patients (57%) and included fractures to the axial and appendicular skeleton, pneumothoraces, a retroperitoneal bleed, and a brachial plexopathy. Eight of 22 patients (37%) sustained injury to the cervical spine. Five of these 8 patients (63%) had neurological deficits (3 complete and 2 incomplete spinal cord injuries). Thirteen of 22 (59%) patients sustained injury to the thoracic or lumbar spine. Ten of these 13 (77%) had neurologic deficits (3 complete and 7 incomplete). Nine of 22 (41%) patients were treated nonoperatively; the remaining 13 (59%) underwent operative intervention.

CONCLUSIONS

Falls from hunting tree stands remain a significant cause of spinal injury and subsequent disability. The best intervention for these injuries is prevention. There is a continued need for hunter safety education to reduce the incidence of these injuries with emphasis on safety harness usage, proper installation and annual inspection of tree stands, hunting in groups with periodic contact, the use of communication devices, and abstinence from alcohol consumption while hunting.

Three-dimensional cartilage formation by bone marrow-derived cells seeded in polylactide/alginate amalgam

Bone marrow-derived cells are considered as candidate cells for cartilage tissue engineering by virtue of their ability to undergo chondrogenesis in vitro when cultured in high density or when embedded within a three-dimensional matrix in the presence of growth factors. This study evaluated the potential of human bone marrow-derived cells for cartilage tissue engineering by examining their chondrogenic properties within a three-dimensional amalgam scaffold consisting of the biodegradable polymer, poly-L-lactic acid (PLA) alone, and with the polysaccharide gel, alginate. Cells were suspended either in alginate or medium and loaded into porous PLA blocks. Alginate was used to improve cell loading and retention within the construct, whereas the PLA polymeric scaffold provided appropriate mechanical support and stability to the composite culture. Cells seeded in the PLA/alginate amalgams and the plain PLA constructs were treated with different concentrations of recombinant human transforming growth factor-beta1 (TGF-beta 1) either continuously (10 ng/mL) or only for the initial 3 days of culture (50 ng/mL). Chondrogenesis was assessed at weekly intervals with cultures maintained for up to 3 weeks. Histological and immunohistochemical analysis of the TGF-beta 1-treated PLA/alginate amalgam and PLA constructs showed development of a cartilaginous phenotype from day 7 to day 21 as demonstrated by colocalization of Alcian blue staining with collagen type II and cartilage proteoglycan link protein. Expression of cartilage specific genes, including collagen types II and IX, and aggrecan, was detected in TGF-beta 1-treated cultures by reverse transcription-polymerase chain reaction analysis. The initiation and progression of chondrogenic differentiation within the polymeric macrostructure occurred with both continuous and the initial 3-day TGF-beta 1 treatment regimens, suggesting that key regulatory events of chondrogenesis take place during the early period of cell growth and proliferation. Scanning electron microscopy revealed abundant cells with a rounded morphology in the PLA/alginate amalgam. These findings suggest that the three-dimensional PLA/alginate amalgam is a potential candidate bioactive scaffold for cartilage tissue engineering applications.

A comparison of three screw types for unicortical fixation in the lateral mass of the cervical spine

STUDY DESIGN

In vitro comparison of three different screws for unicortical fixation in lateral masses of the cervical spine.

OBJECTIVES

To compare the axial load-to-failure of cervical lateral mass screws and their revision screws in a cadaveric model.

SUMMARY OF BACKGROUND DATA

Lateral mass screws are used for posterior fixation of the cervical spine. Risks to neurovascular structures have led many surgeons to advocate unicortical application of these screws, although fixation strength may vary with screw design.

METHODS

Screws from three posterior cervical fixation systems were used: Axis, Starlock/Cervifix, and Summit. Tested were 3.5-mm cancellous screws, along with revision screws for each system. The C3-C6 vertebrae from three cadaveric specimens were fixed with screws inserted into the lateral masses at a depth of 10 mm with 30 degrees cephalad and 20 degrees lateral angulation. Coaxial pullout force was recorded for each primary and revision screw.

RESULTS

Axial load-to-failure (mean +/- SD) of the screws was 459 +/- 60 N for Axis screws, 423 +/- 78 N for Starlock screws, and 319 +/- 97 N for Summit screws. The Axis and Starlock screws were significantly stronger than Summit screws (P = 0.017 and P = 0.067, respectively). The load-to-failure of revision screws was much lower than that of primary screws (Axis 54%, Starlock 56%, Summit 63% of the primary screw), without significant difference between screw types.

CONCLUSIONS

The Axis and Starlock screws resisted significantly greater axial load-to-failure than did the Summit screws. For all three systems, the revision screws could not restore the load-to-failure of the primary screw in this model. The tested unicortical screws had a consistently higher load-to-failure than those previously tested under similar conditions, suggesting that currently available screws may be superior to those previously tested.

Magnetic resonance imaging analysis of soft tissue disruption after flexion-distraction injuries of the subaxial cervical spine

STUDY DESIGN

A retrospective study was performed with the use of magnetic resonance imaging to evaluate the type and degree of soft tissue disruption associated with flexion-distraction injuries of the subaxial spine.

OBJECTIVE

To determine what soft tissue structures are injured in flexion-distraction injuries of the subaxial spine.

SUMMARY OF BACKGROUND DATA

Prior published reports of unilateral and bilateral cervical facet dislocations have described the analyzed mechanisms and biomechanics of this injury subtype. No retrospective magnetic resonance imaging analysis of associated soft tissue disruption has been documented.

METHODS

Magnetic resonance imaging evaluations of the cervical spine were obtained for all patients with a flexion-distraction injury, Stages 2 (unilateral facet dislocation) and 3 (bilateral facet dislocation), between September 1994 and May 1998. Two neuroradiologists, blinded to both clinical and radiographic findings, graded all the soft tissue structures for evidence of attenuation or disruption. The soft tissue structures were graded on a scale of 1 (intact), 2 (indeterminate), or 3 (disrupted).

RESULTS

For this study, 48 patients satisfied the inclusion criteria: 25 with unilateral facet dislocation and 23 with bilateral facet dislocation. Disruption to the posterior musculature, interspinous ligament, supraspinous ligament, facet capsule, ligamentum flavum, and posterior and anterior longitudinal ligaments was found in a statistically significant number of patients with bilateral facet dislocation. For most of these structures, disruption was found to be statistically significant in patients with a unilateral facet dislocation, except for the posterior longitudinal ligament, in which significance was not consistently demonstrated using 95% confidence intervals in the binomial testing. In a comparison between unilateral and bilateral facet dislocations using a two-sided Fisher's exact test, it was found that disruption to the anterior and posterior longitudinal ligaments and the left facet capsule were statistically significant, with all three more prominent in bilateral facet dislocation. A multivariate analysis between unilateral and bilateral facet dislocations showed that disruption to the anterior longitudinal ligament was associated significantly with a bilateral facet dislocation. Disc disruption was found to be associated significantly with both injury types, but was more common in bilateral facet dislocation, although this difference in intergroup comparisons was not statistically significant.

CONCLUSIONS

Unilateral and bilateral facet dislocations of the subaxial spine are associated with damage to numerous soft tissue structures that provide stability to the lower cervical spine. Damage to the posterior longitudinal ligament did not occur consistently in unilateral facet dislocations. Bilateral facet dislocations were associated significantly with disruption to the posterior and anterior longitudinal ligaments and left facet capsule, as compared with unilateral facet dislocations. Magnetic resonance imaging allows visualization of these disruptions.

Distraction extension injuries of the cervical spine

Twenty-four consecutive patients with cervical distraction extension injuries were retrospectively reviewed to study the safety and efficacy of various treatment protocols in this type of cervical spine injury. Sixteen of 24 patients with cervical distraction extension injuries underwent surgical stabilization. All patients undergoing surgical stabilization were noted to have a stable fusion at their latest follow-up. There were three instances of surgically related neurologic deterioration as a result of over-distraction of the anterior column interspace at the time of graft placement. The overall mortality rate was 42% in this aged patient population. Anterior reconstruction of the cervical spine with an anterior cervical graft and plate acting as a tension band is the ideal treatment method for stabilization of acute distraction extension injuries involving primarily the soft tissue structures (anterior longitudinal ligament and intervertebral disc). Type 2 injuries, depending on the degree of displacement and the adequacy of closed reduction, may need to be approached initially posteriorly to obtain adequate alignment, followed by an anterior reconstructive procedure. Great care should be taken during anterior graft placement to avoid over-distraction of the spine. If nonsurgical intervention is selected, close regular radiographic follow-up is necessary to detect early vertebral malalignment, which may predispose to spinal cord dysfunction. Older patients sustaining this injury have a high mortality rate.

The significance of thoracolumbar spinal canal size in spinal cord injury patients

STUDY DESIGN

A prospective, consecutive case series.

OBJECTIVES

To determine the relation between spinal canal dimensions and Injury Severity Score and their association with neurologic sequelae after thoracolumbar junction burst fracture.

SUMMARY OF BACKGROUND DATA

There is a relation in the cervical spine between spinal canal dimension and its association with neurologic sequelae after trauma. A similar relation at the thoracolumbar junction has not been conclusively established.

METHODS

Forty-three patients with thoracolumbar junction burst fractures (T12-L2),13 with and 30 without neurologic deficit, were included. Computed tomographic scans were used to measure the sagittal and transverse diameters and the surface area of the spinal canal at the level of injury, as well as one level above and one level below the fracture level. Injury severity score was calculated for both groups. Statistical analysis comparing those with a neurologic deficit to those without was performed by Student's t test.

RESULTS

The ratio of sagittal-to-transverse diameter at the level of injury was significantly smaller in patients with a neurologic deficit than in those without a neurologic deficit (P < 0.05). The mean transverse diameter at the level of injury was significantly larger in patients with neurologic deficit than in the neurologically intact patients (P < 0.05). The surface area of the canal at the level below the injury was significantly larger in the patients with a neurologic deficit than in those without a deficit (P < 0.05). Patients with a neurologic deficit had a statistically higher Injury Severity Score when admitted than those without a neurologic deficit (P < 0.0001), although the difference became insignificant after the neurologic component of the scoring system was eliminated.

CONCLUSION

There are no anatomic factors at the thoracolumbar junction that predispose to neurologic injury after burst fracture. The shape of the canal after injury, however, as determined by the sagittal-to-transverse diameter ratio, was predictive of neurologic deficit.

The risk of foraminal violation and nerve root impingement after anterior placement of lumbar interbody fusion cages

STUDY DESIGN

Three groups of six embalmed cadaver spines underwent placement of lumbar interbody fusion cages centered either at midline, 10% lateral of midline, or 20% lateral of midline. The spines were evaluated for evidence of neuroforamen violation or nerve root impingement.

OBJECTIVES

To determine the potential for foraminal violation or nerve root impingement after correct placement and lateral misplacement of lumbar interbody fusion cages.

SUMMARY OF BACKGROUND DATA

Radicular symptoms after anterior cage placement have raised some concern about the potential for inadvertent device-related foraminal violation not adequately appreciated by intraoperative fluoroscopy.

METHODS

Preoperative computed tomography scanning and plain radiography was used to measure endplate dimensions at L4-L5 and to template the appropriately sized interbody fusion cages. The cadaveric specimens were randomly divided into three groups of six (Groups I-III) and instrumented at L4-L5 either at midline (I) or 10% (II) or 20% (III) lateral of midline. Postoperative computed tomography and plain radiography was evaluated for evidence of neuroforamen violation, followed by dissection of the specimens.

RESULTS

Foraminal violation occurred in one of six spines in group II (10% off midline) and in three of six spines in group III (20% off midline). Two of the three cadavers in group III with foraminal violation also were noted to have nerve root abutment on computed tomography scans and spinal dissection.

CONCLUSIONS

Excessive lateral placement of lumbar interbody fusion cages may result in foraminal violation and possible nerve encroachment. The "safe zone" for centering the cages extends approximately 5 mm on either side of midline.

Internet resources for spine surgeons

To classify web sites on common spinal disorders as to their utility for the spine surgeon and patient. Five common spinal disorders were used to generate lists of relevant sites. These sites were categorized as to their relevance for patients and surgeons, their sponsoring organization, and their comprehensiveness. A total of 56,249 web sites were found using the five key words on five search engines. Using the "And" operator, a total of 227 web sites were generated. The majority of sites were patient oriented. Physician- or organization-sponsored sites were the most common. Ten sites were found to have comprehensive information for both patients and spine surgeons. Many web sites exist that discuss disorders of the spine. Currently there is not any one web site that contains comprehensive information for both the spine surgeon and patient.

Injuries of the thoracolumbar spine associated with restraint use in head-on motor vehicle accidents

Many authors have described spinal and bodily injuries associated with seat belt use. However, most reports have focused primarily on lap seat belts and resultant flexion-distraction injuries. This retrospective chart review studies the relation between the specific type of restraint or air bag and the resultant thoracolumbar spinal injury subtype and associated bodily injuries. The charts of 221 patients who had sustained thoracolumbar fractures in motor vehicle accidents during a 10-year period were reviewed, and 37 patients were identified whose accidents were clearly described as a frontal collision and whose specific form of restraint was recorded. Among the 15 patients who used a shoulder strap and lap belt device (three-point restraint), 12 patients sustained burst fractures (80%) compared with 4 of the 14 patients (28.6%) restrained with lap seat belts alone. Life-threatening intraabdominal injuries occurred in 57.1% of lap-belted victims and in 26.7% of patients who used three-point restraints, and the character of these injuries also differed. No patients in an automobile in which an air bag deployed sustained major associated bodily injuries. Among restrained occupants of head-on motor vehicle accidents who have sustained a thoracolumbar fracture, patients using lap belts are more likely to sustain the classic flexion-distraction injury patterns, whereas patients using three-point restraints may sustain a higher incidence of burst fractures. In addition, three-point restraints are associated with a decreased risk of intraabdominal injury compared with lap seat belts.

A plate-rod device for treatment of cervicothoracic disorders: comparison of mechanical testing with established cervical spine in vitro load testing data

Posterior cervical internal fixation has long been accomplished using wires, hooks, and rods. More recently, the cervical lateral mass screw and plate or rod systems have been used effectively in unstable lower cervical spine disorders. Each form of fixation has its advantages and disadvantages. Interspinous wiring and lateral mass screw placement obviate canal penetration in the cervical region but are associated with a potential neurologic risk as a result of canal encroachment. Minor canal intrusion by laminar hooks in the thoracic spine pose a lesser neurologic risk than in the cervical region. To exploit the benefits and safety features of spinal instrumentation, a combination plate rod construct (PRC) has been developed that obviates canal penetration in the cervical region by way of lateral mass and cervical pedicle screw fixation and hooks or wires in the thoracic spine. A biomechanical analysis of the PRC device was performed and compared with the in vivo maximal load data of the cervical spine and established maximal load data of the Roy-Camille posterior cervical fixation system. The PRC has greater strength and resistance to failure than is necessary to sustain maximal in vivo cervical spine loads, and it has also compared favorably with the parameters of the Roy-Camille system. The PRC device, or variations on it, is an excellent option for spinal fixation across the cervicothoracic junction because of its superior biomechanical qualities and versatility in stabilizing a complex anatomic junction of the spine.

Placement of pedicle screws in the human cadaveric cervical spine: comparative accuracy of three techniques

STUDY DESIGN

This investigation was conducted in two parts. In the first part, a morphometric analysis of critical cervical pedicle dimensions were measured to create guidelines for cervical pedicle screw fixation based on posterior cervical topography. In the second part of the study, a human cadaver model was used to assess the accuracy and safety of transpedicular screw placement in the subaxial spine using three different surgical techniques: 1) using surface landmarks established in the first part of the study, 2) using supplemental visual and tactile cues provided by performing laminoforaminotomies, and 3) using a computer-assisted surgical guidance system.

OBJECTIVE

To assess the accuracy of transpedicular screw placement in the cervical spine using three surgical techniques.

SUMMARY OF BACKGROUND DATA

A three-column fixation device implanted to secure an unstable cervical spine can be a valuable tool with a biomechanical advantage in the spine surgeon's armamentarium. Despite this advantage, concerns over surgical neurovascular complications have surfaced. Cadaver-based morphometric measurements used to guide the surgeon in the placement of a pedicle screw show significant variability, raising legitimate concerns as to whether transpedicular fixation can be applied safely.

METHODS

Precise measurements of 14 human cadaveric cervical spines were made by two independent examiners of pedicle dimensions, angulation, and offset relative to the lateral mass boundaries. On the basis of this analysis, guidelines for pedicle screw placement relative to posterior cervical topography were derived. In the second part of the study, 12 human cadaveric cervical spines were instrumented with 3.5-mm screws placed in the pedicles C3-C7 according to one of three techniques. Cortical integrity and neurovascular injury were then assessed by obtaining postoperative computed tomography scans (1-mm cuts) of each specimen. Cortical breaches were classified into critical or noncritical breaches.

RESULTS

Linear measurements of pedicle dimensions had a wide range of values with only fair interobservercorrelation. Angular measurements showed similarangulation in the transverse plane (40 degrees ) at each level. With respect to the sagittal plane, both C3 and C4 pedicles were oriented superiorly relative to the axis of the lateral mass, whereas the C6 and C7 pedicles were oriented inferiorly. The dorsal entry point of the pedicle on the lateral mass defined by transverse and sagittal offset had similar mean values with wide ranges, although there often was excellent correlation between observers. There were no significant interlevel, right/left, or male/female differences noted with respect to offset. Using one of three techniques, 120 pedicles were instrumented. In group 1 (morphometric data): 12.5% of the screws were placed entirely within the pedicle; 21.9% had a noncritical breach; and 65. 5% had a critical breach. In group 2 (laminoforaminotomy), 45% of the screws were within the pedicle; 15.4% had a noncritical breach; and 39.6% had a critical breach. In group 3 (computer-assisted surgical guidance system), 76% of the screws were entirely within the pedicle; 13.4% had a noncritical breach; and 10.6% had a critical breach. Regardless of the technique used, the vertebral artery was the structure most likely to be injured.

CONCLUSIONS

On the basis of the morphometric data, guidelines for cervical spine pedicle screw placement at each subaxial level were derived. Although a statistical analysis of cadaveric morphometric data obtained from the cervical spine could provide guidelines for transpedicular screw placement based on topographic landmarks, sufficient variation exists to preclude safe instrumentation without additional anatomic data. Insufficient correlation between different surgeons' assessments of surface landmarks attests to the inadequacy of screw insertion techniques in the cervical spine based on such specific topographic guide

SmMAK16, the Schistosoma mansoni homologue of MAK16 from yeast, targets protein transport to the nucleolus

The SmMAK16 gene from Schistosoma mansoni was cloned by chance when an adult worm cDNA library was probed with antiserum to affinity-purified S. mansoni GSH S-transferases. SmMAK16 encodes a hydrophilic protein of 259 amino acids with a molecular mass of 31 kDa. The protein shares 43% sequence identity and 66% similarity to the nuclear protein MAK16 of Saccharomyces cerevisiae that has been implicated both in cell cycle progression and biogenesis of 60S ribosomal subunits. Both proteins display a similar degree of sequence similar to the hypothetical protein CeMAK16 from Caenorhabditis elegans. These proteins share a number of apparent protein motifs, including two nuclear localization signals (NLS), multiple sites for phosphorylation by protein kinase CK2 and four conserved cysteine residues that resemble a zinc binding domain. SmMAK16 mRNA is more highly expressed in adult female worm than males. Recombinant SmMAK16 was phosphorylated by human protein kinase CK2. When chimeric constructs containing SmMAK16 fused the green fluorescent protein (GFP) were transiently transfected into COS-7s cells, the reporter was localized not in nuclei, but exclusively in nucleoli. The yeast and nematode homologues were likewise able to direct nucleolar accumulation of the fluorescent reporter. The high degree of sequence conservation together with the ability to direct nucleolar protein transport supports the hypothesis that MAK16 proteins play a key role in the biogenesis of 60S subunits.

Health outcome assessment before and after anterior cervical discectomy and fusion for radiculopathy: a prospective analysis

STUDY DESIGN

A prospective assessment, performed using the Health Status Questionnaire, of the outcomes for 28 patients with cervical radiculopathy treated with one- or two-level anterior cervical discectomy and fusion.

OBJECTIVE

To assess patient outcome using the Health Status Questionnaire after one- or two-level anterior cervical discectomy and fusion.

SUMMARY OF BACKGROUND DATA

Although outcomes for many types of surgical procedures already have been evaluated, few have focused on the results of cervical surgery.

METHODS

Before and after anterior cervical discectomy and fusion for cervical radiculopathy, 28 patients filled out the Health Status Questionnaire. The average follow-up interval was 21.8 months. There were 10 men and 18 women, with an average age of 44 years. All outcome instruments were graded for individual scores of general health, physical function, role limitation because of physical health problems, role limitation because of emotional problems, social function, mental health, bodily pain, and energy. Data were analyzed using the age (< 55 vs. > 55), worker's compensation status, and education status of the patient. Preoperative and postoperative scores were compared for each subscale.

RESULTS

Statistically significant improvements were found in postoperative scores for bodily pain (P < 0.001), vitality (P = 0.003), physical function (P = 0.01), role function/physical (P = 0.0003), and social function (P = 0.0004). No significant differences were found before and after surgery for three health scales: general health, mental health, and role function associated with emotional limitations. Age, educational status, and history of compensation litigation did not appear to affect outcome measures.

CONCLUSIONS

Although this is a preliminary report involving 28 patients, it would appear, based on the results of the Health Status Questionnaire, that anterior cervical discectomy and fusion performed on appropriately selected patients is a highly reliable surgical procedure for the management of cervical radiculopathy. Additional disease-specific questions may provide more sensitivity in evaluating radiculopathy after surgical and nonsurgical intervention.

Management of symptomatic lumbar pseudarthrosis with anteroposterior fusion. A functional and radiographic outcome study

STUDY DESIGN

An independent retrospective review of 37 patients undergoing 39 anteroposterior lumbar fusions for lumbar pseudarthrosis repair between 1984 and 1990.

OBJECTIVES

To evaluate radiographically and functionally the results of the combined anteroposterior fusion for the management of symptomatic lumbar pseudarthrosis, and to assess risk factors for functional failure after the procedure.

SUMMARY OF BACKGROUND DATA

Most reported techniques of pseudarthrosis repair involve posterior fusion with no instrumentation, posterior fusion with instrumentation, or anterior fusion alone. The results of lumbar pseudarthrosis repair are poor. Fusion rates range from 30% to 70%, with only a 30% to 50% rate of functional success.

METHODS

Thirty-nine procedures were assessed in 37 patients. The outcomes were assessed radiographically (solid fusion vs. pseudarthrosis) and functionally (success vs. failure). Radiographs were assessed at follow-up examination for consolidation of fusion anteriorly and posteriorly. Functional outcome was graded by using multiple instruments, including data from chart review and the follow-up outcome questionnaire. A functional failure score that took into account 10 items was developed.

RESULTS

In this patient population (37 patients, 59% with a smoking history, 71% with compensation or legal claims), there was a 10% pseudarthrosis rate. Pseudarthrosis was defined when one or more levels were involved and when it occurred anteriorly and posteriorly. In 12 patients (35%), the outcome was rated as functional failure. The presence of one or more abnormal neurologic findings and significant narcotic use before surgery significantly increased the chance of a patient's outcome being functional failure. Workmen's Compensation or legal status before surgery also increased the chance of functional failure, though this correlation was not statistically significant.

CONCLUSIONS

A combined anterior and posterior approach for the management of symptomatic lumbar pseudarthrosis is a viable alternative to posterior fusion alone. In fact, this procedure affords a higher fusion rate based on radiographic assessment. Functional failure rates may be decreased by using caution for those patients using narcotics regularly before surgery or in those with unexplained preoperative neurologic abnormal findings.

The role of human bone morphogenetic proteins in spinal fusion

The attainment of a stable arthrodesis is critical to the successful management of some types of spinal disorders. Autologous iliac-crest bone graft has been the most commonly utilized substance associated with predictable healing in spinal fusion applications. Although alternative graft substances exist, these have not been shown to be as uniformly effective in achieving spinal fusion. Because of the morbidity associated with bone autograft harvest, there is increasing interest in alternative graft substances and especially in the osteoinductive abilities of bone morphogenetic proteins (BMPs). Several animal models have demonstrated that BMP-containing allograft or synthetic carrier medium is as effective as or superior to autograft bone in promoting spinal fusion. Furthermore, the limited number of human trials utilizing BMPs to treat nonunions in the appendicular skeleton indicate that the results found in animal models will be reproducible in the clinical setting.

Surgical management of cervical radiculopathy

Cervical radiculopathy presents as pain in a dermatomal distribution. Despite conservative nonoperative therapy, a large subset of patients will require surgical intervention. Indications for surgery include recalcitrant radiculopathy despite nonoperative treatment for more than 6 weeks and progressive motor deficit or disabling motor deficit (deltoid palsy, wrist drop) prior to 6 weeks. Anterior and posterior approaches have both yielded successful results in appropriately selected patients. Anterior cervical diskectomy and fusion is the generally preferred treatment for radiculopathy when there is a significant component of axial neck pain, when the disease is centrally located, or when there is any degree of segmental kyphosis. Posterior laminoforaminotomy is an acceptable choice for lateral soft disk herniations with predominant arm pain and for caudal lesions in large, short-necked individuals.

The efficacy of using an image-guided Kerrison punch in performing an anterior cervical foraminotomy. An anatomic analysis

STUDY DESIGN

This study comprised two parts: first, a feasibility study to determine the efficacy of using an image-guided Kerrison punch while performing a foraminotomy during an anterior cervical decompression and, second, an anatomic analysis using vector measurement to determine the distance from the entrance of the neuroforamen to the medial margin of the vertebral artery in the subaxial cervical spine.

OBJECTIVE

To assess the feasibility of using an image-guided Kerrison punch when performing an anterior foraminotomy and to obtain data regarding the distance from the vertebral artery to the entrance of the neuroforamen.

SUMMARY OF BACKGROUND DATA

The documented incidence of catastrophic iatrogenic vertebral artery injury in anterior cervical decompression is low. The use of a real-time image-guidance surgical system should reduce the risk of this complication.

METHODS

Twelve cadaveric cervical spines were harvested. Standard anterior cervical discectomies with bilateral foraminotomies were performed in the subaxial cervical spine using an image-guided Kerrison. Surgically significant morphometric data were measured using a computer-assisted image-guided surgical system.

RESULTS

Successful navigation into all neuroforamina in the subaxial cervical spine was attained using the image-guided Kerrison punch. The vector measurement from the neuroforamen to the vertebral artery averaged 5.8 +/- 1.2 mm at C3-C4, 6.5 +/- 1.6 mm at C4-C5, 7.9 +/- 1.4 mm at C5-C6, and 9.1 +/- 1.8 mm at C6-C7. Statistically significant differences (P < 0.05) were found between all cervical levels except C3-C4 and C4-C5.

CONCLUSION

An image-guided Kerrison punch may be used successfully when performing cervical foraminotomies during an anterior cervical discectomy, thus eliminating the risk of potential vertebral artery injury. These data confirm previous findings by other authors. Knowledge of these data may aid the spine surgeon in performing a foraminotomy during anterior cervical decompression.

Management of degenerative disc disease above an L5-S1 segment requiring arthrodesis

Clear guidelines exist for treating spondylolisthetic deformity and instability. How the surgeon handles adjacent-level degenerative disease is not as well established. Because magnetic resonance imaging now provides us with far more information on the "health" of radiographically normal intervertebral discs, the treatment of dehydrated or degenerated discs adjacent to a fusion is becoming more problematic. In this discussion, two experts discuss their approach to symptomatic lumbosacral spondolisthesis accompanied by adjacent-level disc degeneration. Drs. Herkowitz and Abraham believe strongly that the adjacent segment should be left alone, whereas Dr. Albert recommends extending the fusion in many instances.

Image-guided anterior cervical corpectomy. A feasibility study

STUDY DESIGN

A feasibility study was performed to determine the efficacy of using image-guided frameless stereotaxy to perform anterior corpectomy of the cervical spine.

OBJECTIVE

To assess the feasibility of using image-guided stereotaxy in performing anterior cervical corpectomy.

SUMMARY OF BACKGROUND DATA

Anterior cervical decompression including discectomy and corpectomy is a commonly performed procedure. Particular concern about invasion of the vertebral artery arises while performing this procedure to gain maximal lateral decompression. At present, surgeons have only landmarks and experience to guide them in performance of this potentially dangerous procedure.

METHODS

Four cadavers (average age, 40.3 years) were used. A lateral corpectomy trough was created in Group 1 by a standard technique using visual landmarks. In the second group of corpectomy troughs, an image-guided frameless stereotactic system was used. After completion of the experiment, each cadaver had a corpectomy trough at every level on one side performed in a standard manner and on the other with image guidance. Using the image guidance system, an independent observer measured the distance from the corpectomy trough (lateral border) to the medial border of the foramen transversarium.

RESULTS

The average distance from the lateral border of the trough to the medial border of the foramen transversarium in the standard trough group was 5.10 mm (range, 1.72-7.71 mm), and the average distance from the medial border of the foramen transversarium to the image-guided trough was 4.34 mm (range, 3.34-5.48 mm). The trend of the comparison between the two troughs was toward significance at P = 0.08.

CONCLUSIONS

Image-guidance provided improved accuracy when compared with that of a standard technique, implying clinical potential for image-guided corpectomy. Less variability is seen using an image-guided approach.

Efficacy of magnetic resonance imaging in the evaluation of posterior cervical spine fractures

STUDY DESIGN

A retrospective study using two independent, blinded musculoskeletal radiologists to evaluate the sensitivity, specificity, and predictive value of cervical spine magnetic resonance imaging in detecting posterior element fractures of the cervical spine.

OBJECTIVE

To evaluate the sensitivity, specificity, and predictive value of magnetic resonance imaging, using computed tomographic scanning as the gold standard, in the diagnosis of posterior element cervical spine fractures.

SUMMARY OF BACKGROUND DATA

Few investigators have evaluated the accuracy of magnetic resonance imaging in the determination of cervical spine fractures.

METHODS

From January 1994 through June 1996, 75 cervical spine fractures in 32 patients were confirmed by computed tomography. Two musculoskeletal radiologists who were blinded to the clinical history and presence or absence of cervical injury among the study population, independently evaluated each cervical magnetic resonance image recording the presence or absence of soft tissue or bony injury.

RESULTS

The overall sensitivity and specificity rates for the diagnosis of a posterior element fracture by magnetic resonance imaging was 11.5% and 97.0%, respectively. The positive predictive value for this group was 83%, and the negative predictive value was 46%. In reference to anterior fractures, the sensitivity was 36.7% and the specificity 98%. Positive and negative predictive values were 91.2% and 64%, respectively.

CONCLUSIONS

Magnetic resonance imaging was not effective in recognizing bony injury to the cervical spine and in particular was not as sensitive or as specific as computed tomography in identifying cervical spinal fractures. Computed tomography remains the study of choice for the detection and precise classification of bony injuries to the cervical region, especially when plain radiographs are difficult to evaluate. Magnetic resonance imaging, although not as effective as computed tomography in defining specific bony disorders, remains the gold standard in the evaluation of spinal cord injury, occult vascular injury, and intervertebral disc disruption (hyperextension injury), including herniation and other soft tissue disorders (hematoma, ligament tear).

Transpedicle screw fixation of the cervical spine

The use of posterior cervical spine fixation has become increasingly popular in recent years. Dissatisfaction with lateral mass fixation, especially at the cervicothoracic junction, has led spine surgeons to use cervical pedicle screw fixation for reconstruction in numerous cervical spine disorders. The biomechanical advantage of a three-column fixation device implanted to secure an unstable cervical spine has proven to be a valuable tool in the spine surgeon's armamentarium. Successful placement of a pedicle screw in the cervical spine requires a sufficient three-dimensional understanding of pedicle morphology to allow accurate identification of the ideal screw axis. Variability in cadaveric based morphometric measurements used to guide the surgeon in the placement of a pedicle screw has raised legitimate concerns as to whether transpedicle fixation can be applied without significant neurovascular complications. The emergence of computer assisted image guidance systems may be implemented in the operative protocol to improve the accurate placement of a pedicle screw. The indications for placement of a pedicle screw in the cervical spine are beginning to evolve. Only surgeons experienced in transpedicle screw fixation and surgery of the cervical spine should perform this method of instrumentation.

Postlaminectomy kyphosis

Postlaminectomy kyphosis is a rare but potentially catastrophic complication of laminectomy performed to treat cervical myelopathy. The best strategy for prevention is awareness of the sagittal plane before surgery in patients with cervical spondylotic myelopathy. An understanding of the biomechanical forces placed on the cervical spine, the normal structures contributing to stability and the underlying pathologic process helps in the prevention and ultimate treatment of postlaminectomy kyphosis. This is a review of the risk factors, biomechanics, work-up, and surgical treatment of postlaminectomy kyphosis.

Anterior junctional plate in the cervical spine

STUDY DESIGN

This study introduces a useful plating technique for complex reconstructions of the anterior cervical spine.

OBJECTIVE

To provide a short-segment-buttressing technique for the stabilization of long anterior fusion constructs in the cervical spine while avoiding the potential morbidity and risks associated with long-segment anterior cervical plating.

SUMMARY OF BACKGROUND DATA

Anterior fibular or iliac crest strut grafts are at risk of dislodging when used after multisegment (> 3 vertebrae) corpectomy in various spinal disorders. Long-segment anterior cervical plates have been used to reduce the incidence of graft displacement and migration but have been shown to increase risk for early failure because of screw dislodgement.

METHODS

Eleven patients with cervical myelopathy underwent a multilevel (average 3.36 levels) corpectomy followed by the placement of a fibular or iliac crest strut graft. An anterior short-segment locking or buttress plate was then placed in the vertebral body, either inferior or superior to the seated graft, depending on the ease of insertion and quality of the host bone. Posterior segmental fixation was performed in all patients during the same procedure. The average follow-up was 30.8 months (range, 25-36 months).

RESULTS

No incidence of plate or graft migration (anteroposterior plane) or dislodgement was reported in this series. One graft fracture occurred secondary to the placement of a intragraft screw through an anterior junctional plate. No patients experienced clinical morbidity related to the junctional plate. Neurovascular complications and wound complications were not encountered in any of these patients. All had an improvement in their neurologic symptoms, and 10 of the 11 patients had fusion documented on plain radiographs.

CONCLUSIONS

The use of a junctional plate anteriorly along with posterior segmental fixation and fusion may prevent or decrease the incidence of graft and internal fixation dislodgement after a long-segment cervical reconstruction procedure.

Cervical degenerative disease: rationale for selecting the appropriate fusion technique (Anterior, posterior, and 360 degree)

Many options exist for those treating cervical disc herniation, spondylosis, and deformity. This article examines the options for cervical degenerative fusions, the appropriate choice of technique (anterior, posterior, or combined anterior/posterior techniques), as well as bone graft and instrumentation choices.

The changing nature of admissions to a spinal cord injury center: violence on the rise

The purpose of this study was to analyze changing etiologies for admission to a spinal cord injury center. This study was designed to retrospectively analyze the etiology of admissions to a spinal cord injury center during a 15-year period, specifically gunshot versus nongunshot wound injuries. Gunshot wounds are a well-recognized cause of spinal cord injury. In some centers, up to 52% of admissions are due to this, and these trends are believed to be increasing. All patients with spinal cord injury admitted to our center between 1979 and 1993 were analyzed. Frequencies of specific etiologies were determined and then comparisons were made between gunshot wound and nongunshot wound groups. Factors analyzed included age, male/female ratio, ethnic make-up, marital status, employment status, level of injury, and neurologic status. One thousand eight hundred seventeen patients were included. Overall, gunshot wound spinal cord injuries compromised 16.9% of injuries. A clear trend of increasing numbers of admissions was seen between 1984 and 1993 because of this. Gunshot wounds and nongunshot wounds differed dramatically in terms of age, ethnic make-up, marital status, employment status, and neurologic status. Cost attributed to treating gunshot wound injuries at our center for 1993 was 5.4 million dollars. Gunshot wounds as a cause of spinal cord injury are increasing at an alarming rate. The demographics of the gunshot wounds and nongunshot wound spine cord injuries differ significantly.

Foraminal pressure changes during intervertebral distraction simulating anterior cervical discectomy

Distraction of the disc space over baseline height has been shown to increase foraminal size. The purpose of this procedure is to determine pressure changes, with disc space distraction simulating an anterior cervical discectomy and fusion (ACDF). An analysis of pressure changes during disc space distraction at C5-C6 was performed. Data were analyzed for maximal pressure observed and for pressure change with prolonged distraction. Five cadaveric specimens underwent a discectomy at the C5-C6 level. Distraction of the disc space was performed and pressure measurements were obtained from within the foramen. Measurements were made for maximal pressure with an intact posterior longitudinal ligament (PLL), divided PLL, and with the nerve root removed from within the foramen. Pressures were also recorded with prolonged distraction until a steady state was achieved. Incremental distraction of +2, +4, and +6 mm resulted in pressure increases within the foramen. Sectioning of the PLL did not affect these increases. Removal of the nerve root from the foramen resulted in pressure increases; however, these were not significantly different from baseline. Prolonged distraction produced an initial increase and a gradual return toward baseline. Final pressures still differed significantly from baseline. Increase intraforaminal pressures can be seen with increasing disc space distraction such as occurs during an ACDF. This suggests that either the foramen narrows in at least one dimension and/or soft-tissue attachments to the nerve produce a tensile force in the nerve as they tighten. The pressure increases relax over time.

Use of cervicothoracic junction pedicle screws for reconstruction of complex cervical spine pathology

STUDY DESIGN

A retrospective review of 21 patients in which cervical pedicle screw fixation was used at C7 with or without upper thoracic pedicle screw fixation.

OBJECTIVE

To evaluate the use of pedicle screw placement in the lower cervical spine.

SUMMARY OF BACKGROUND DATA

The use of posterior cervical spine fixation, including lateral mass fixation, has become increasingly popular in recent years. However, lateral mass fixation at C7 is often hindered by lack of substantial high quality bone. The end level of long cervical spine constructs is frequently C7 or T1. Dissatisfaction with lateral mass fixation at C7 and T1 led the authors to use lower cervical pedicle screw fixation for several cervical spine disorders.

METHODS

Twenty-one patients who had undergone cervical pedicle screw fixation at C7 were reviewed retrospectively. There were 12 males and 9 females, with an average age of 52 years. All pedicle screws were placed, after direct palpation of the pedicle, with a right angle nerve hook after laminoforaminotomy at C7.

RESULTS

There were no neurologic complications related to pedicle screw placement, and no patient was symptomatically worse after the operation. Six patients with root pathology improved. Of 14 patients with cervical myelopathy, 12 improved at least one Nurick grade, and 2 had no improvement. There were no failures of fixation or complications related to pedicle fixation at a minimum of 1 year follow-up.

CONCLUSION

Pedicle screws in C7 placed with laminoforaminotomy and palpation technique appears to be safe and efficacious. Excellent fixation can be achieved.

Neurologic deterioration after cervical spinal cord injury

Neurologic deterioration after cervical spinal cord injury (SCI) at a regional spinal cord center was examined. This study examined the incidence of neurologic deterioration as well as associated risk factors in our patient population. Up to 5.8% of cervical SCI patients have been noted to deteriorate neurologically after admission. Risk factors have been early surgery, halo application, traction, and Stryker frame rotation. All cervical SCI patients admitted between 1978 and 1993 who had neurologic deterioration were studied for characteristics of their event, operative status, risk factors, mortality, and neurologic return at 1 year postinjury. Patients were divided into minor and major groups based on the degree of neurologic loss. Nineteen of 1,031 patients were identified as neurologically deteriorated (1.84%). There were 8 major and 11 minor group patients. The average time from injury to deterioration was 3.95 days. Of 10 patients undergoing surgery at < or =5 days, 8 deteriorated postoperatively. Potential risk factors were ankylosing spondylitis (three patients), sepsis (four patients), and intubation (four patients). Neurologic recovery at 1 year showed that 11 of 12 patients were improved. Neurologic deterioration occurred in 1.84% of our patients. Deteriorations were associated with surgery at <5 days after injury, ankylosing spondylitis, sepsis, and intubation.

Accuracy of SPECT scanning in diagnosing pseudoarthrosis: a prospective study

The present study attempted to analyze the efficacy of single photon emission computed tomography (SPECT) in diagnosing pseudoarthrosis after fusion using surgical exploration as the gold standard. This study examined the SPECT scans of 38 patients before they underwent surgical exploration of their fusion mass for suspected pseudoarthrosis or in conjunction with instrumentation removal. Surgical findings were compared with the radiologists' findings to determine the efficacy of SPECT in diagnosing pseudoarthrosis. Radiographic determination of pseudoarthrosis has been difficult after attempted fusion of the spine. Multiple radiographic modalities have been touted as accurate depicters of the failure of spinal fusion. However, no method has been found to be highly accurate in the clinical setting. Thirty-eight patients (mean age = 42.8, 21 males/17 females, 35 of 38 with instrumentation) underwent SPECT scans before surgical exploration of their fusion mass for suspected pseudoarthrosis or in conjunction with instrumentation removal as part of this prospective study. The average interval from their fusion procedure until their SPECT scan was 23.9 months (range, 9-120 months). All surgical findings were recorded with regard to solidity of the fusion and the level of the possible pseudoarthrosis. All SPECT scans were read at a time after surgery by an independent nuclear radiologist who had not read their SPECT scans before surgery and who did not know the results of exploration. Results of the radiologist's reading were then compared with surgical exploration findings, and sensitivity and specificity was calculated. There were 24 solid fusions and 14 pseudoarthroses. SPECT scans correctly identified 7 of the 14 pseudoarthroses and 14 of the 24 solid fusions. This represents a sensitivity of 0.50 and a specificity of 0.58. SPECT scanning correctly diagnosed the one solid fusion and two pseudoarthrosis patients in the three patients who had no instrumentation. This study demonstrates that SPECT scanning alone is inaccurate in diagnosing pseudoarthrosis when using surgical exploration as the gold standard. Given recent pressures for cost containment, we cannot recommend SPECT scanning as a routine modality for use in the diagnosis of pseudoarthrosis. We cannot define the accuracy of SPECT scanning used together with computed tomography scans, plain films, or other radiographic modalities in the diagnosis of pseudoarthrosis.

Variation in surgical opinion regarding management of selected cervical spine injuries. A preliminary study

STUDY DESIGN

The opinions of orthopedic surgeons and neurosurgeons were compared regarding appropriate management of selected cervical injuries and the timing of stabilization.

OBJECTIVE

To determine whether there is consistency of opinion regarding the management of cervical trauma.

SUMMARY OF BACKGROUND DATA

Numerous forms of management for cervical trauma exist, but there are few consistent recommendations. No previous study has been done to determine uniformity of preferences of the surgeons who manage these injuries.

METHODS

Thirty-one orthopedic surgeons and neurosurgeons were given a brief clinical situation and pertinent radiographic studies of five selected cervical injuries. Management options included halo and nonhalo orthoses, traction, and various forms of anterior and/or posterior procedures. The surgeons rated, in whole numbers from 1 to 10, their opinions on the appropriateness of each technique. Each surgeon was given a case of a "generic" cervical injury, in which stabilization was required and for which preoperative alignment was adequate in traction. They gave opinions on the timing of stabilization, with a choice of four time frames. Four neurologic situations were rated, ranging from intact to complete cord injury.

RESULTS

Of 46 possible responses to the five test cases regarding appropriateness, 18 ranged from 1 to 10, the largest possible variation. Only 2 had a range of 5 or less, implying better consensus among tested surgeons. Mean values ranged from 1.9 to 9.5. Agreementamong respondents regarding appropriateness was slight with a range of kappa statistics from 0.09 to 0.14. Of 16 possible responses regarding timing, 14 were within a range of 8 or higher. Within 24 to 72 hours was the generally preferred time frame, with all possible responses showing a range of 3 or 4. Results of a multiple analysis of variance showed no significant differences among respondents.

CONCLUSION

There is a large variety of opinion regarding appropriateness of specific operative and nonoperative management procedures and surgical timing among the surgeons polled who manage cervical trauma. This implies that there is no widely accepted standard management procedure for many of these injuries.

Long-term evaluation of vertebral artery injuries following cervical spine trauma using magnetic resonance angiography

STUDY DESIGN

A prospective study to determine the long-term outcome of traumatically induced vertebral artery injuries. Magnetic resonance angiography was performed at the time of cervical injury and at a follow-up office visit.

OBJECTIVE

To determine the long-term outcome in terms of arterial flow competency of traumatically induced vertebral artery injuries.

SUMMARY OF BACKGROUND DATA

Vertebral artery injury associated with cervical spine trauma has been well documented; however its healing or nonhealing potential has not been elucidated.

METHODS

During the 7-month period from July 1993 to January 1994, all patients admitted to the authors' institution with cervical spine injuries underwent magnetic resonance imaging and magnetic resonance angiography of the cervical spine to determine the patency of their vertebral arteries. Magnetic resonance angiography was performed at the time of injury and at a follow-up office visit. Twelve of 61 patients were found to have a lack of signal flow within one of their vertebral vessels during this study period.

RESULTS

Eighty-three percent of the patients (five of six) who were available for follow-up observation in this study did not manifest flow reconstitution of their vertebral arteries after an average 25.8-month follow-up period.

CONCLUSIONS

According to these data, most patients with vertebral artery injuries after nonpenetrating cervical spine trauma do not reconstitute flow in the injured vertebral arteries. This lack of flow must be considered if future surgery in this region of the cervical spine is contemplated.

The benefits of early decompression in cervical spinal cord injury

Decompression and stabilization have been shown to improve neurologic outcome in cases of cervical spine trauma with proven compression of the spinal cord. This paper reviews experimental and clinical research to clarify the benefits of early surgery for cervical spinal cord injury. The direct clinical benefit of early surgery is a theoretic improvement in neurologic recovery over that of delayed surgery. Additional benefits of early surgery include the clinical advantages of a decreased length of hospitalization and its associated complications and a decreased time to rehabilitation and mobilization. Proper, timely surgical intervention can better the physiologic environment so as to allow for maximum neurologic improvement.

Magnetic resonance imaging analysis of lumbar disc changes below scoliosis fusions. A prospective study

STUDY DESIGN

The authors of this prospective study examined the preoperative and 3-year postoperative magnetic resonance images of 14 patients undergoing anterior and posterior fusion and/or posterior fusion only for scoliosis. All magnetic resonance images were ready by two independent neuroradiologists, who were blinded to the purposes of the study, for the presence of disc narrowing, signal decrease on T2, or herniated nucleus pulposus before and after surgery. Particular attention was paid to the disc changes at the level directly below the end vertebral level of the fusion and two levels below the fusion in the lumbosacral spine existing before surgical intervention.

OBJECTIVES

To evaluate the potential for disc degeneration distal to long scoliosis fusions with end fusion levels in the mid to lower lumbar spine.

SUMMARY OF BACKGROUND DATA

The determination of end levels of fusion for contructs presently used to manage adult scoliotic deformity has been evaluated in terms of correction of curvature and late decompensation in coronal and sagittal plane balance after fusion. However, the natural history of the caudal, free-motion segments in terms of degeneration and/or correlation with pain has not yet been addressed.

METHODS

Fourteen patients undergoing scoliosis fusion underwent magnetic resonance imaging before surgery and approximately 3 years after surgery. The scans were reviewed by two independent neuroradiologists who looked at three degenerative indices at the disc below the area of scoliosis fusion. The authors analyzed rates of change of the three degenerative indices in the pre- and postoperative magnetic resonance images and created associations between the observed changes on the magnetic resonance images and the clinical outcomes of pain, the presence or absence of solid fusion, and the need for repeat surgery.

RESULTS

Estimates of the rates of change of the three degenerative indices one or two levels below the fusion were as follow: the chance of disc narrowing, .2-34%; the chance of a decreasing signal on T2, 5-54%, with a 23% incidence among this group; and the chance of herniated nucleus pulposus, 0-34%. There was a significant correlation between the presence of back and/or leg pain and the signal decrease one level below the fusion (P = .04).

CONCLUSIONS

If these results are corroborated in a larger sample size, surgeons who manage deformity may have to consider altering fusion levels at the time of fusion based on magnetic resonance imaging predictors. The present data may help to inform patients about the risk of developing junctional degenerative changes and potential symptoms from these changes below scoliosis fusions.

Relationship of total hip arthroplasty outcomes to other orthopaedic procedures

The Medical Outcomes Study Short Form-36 was used preoperatively and 2 years postoperatively to compare patients' self reported assessment of health and function between 151 patients who had primary total hip replacement and 49 patients who had total hip revision, 149 patients who had primary total knee replacements, 41 patients who had lumbar laminectomy, and 43 patients who had scoliosis surgery. Primary total hip arthroplasty and lumbar laminectomy posted equivalent followup scores. Primary total hip arthroplasty showed significant improvements in physical function and health perception when compared with revision total hip arthroplasty; all other health parameters were similar. Primary total hip arthroplasty showed significantly better followup scores and greater improvement in scores in four of nine categories of the SF-36 when compared with primary total knee arthroplasty (despite identical scores preoperatively). Despite a higher level of assessed health preoperatively, patients who had scoliosis surgery compared least favorably with patients who had primary total hip arthroplasty at 2 years followup. In terms of patient self assessment of health and function, primary total hip arthroplasty and lumbar laminectomy for radiculopathy gave the best results.

Steroids and gunshot wounds to the spine

OBJECTIVE

The second National Acute Spinal Cord Injury Study demonstrated that there were neurological benefits from "spinal cord injury" doses of methylprednisolone for blunt spinal cord injuries. In this review, we examined the relative risk/benefit ratio of intravenously treating spinal gunshot wound victims with steroids.

METHODS

A retrospective review was conducted of 254 consecutive patients who were treated between 1979 and 1994 for gunshot wounds to the spine (C1-L1) and a spinal cord injury. Three subgroups were established based on the administration of the steroids methylprednisolone (National Acute Spinal Cord Injury Study 2 protocol), dexamethasone (initial dose, 10-100 mg), and no steroids. All patients who received steroids were initially treated at another hospital and then transferred. No patients received steroids at our institution. The data analyzed included neurological outcome and infectious and noninfectious complications.

RESULTS

No statistically significant neurological benefits were demonstrable from the use of steroids (methylprednisolone, dexamethasone). Infectious complications were increased in both groups receiving steroids (not statistically significant). Gastrointestinal complications were significantly increased in the dexamethasone group (P = 0.021), and pancreatitis was significantly increased in the methylprednisolone group (P = 0.040). The mean duration of follow-up was 56.3 months.

CONCLUSION

In this retrospective, nonrandomized review, no neurological benefits were detectable from intravenously administered steroids after a gunshot wound to the spine. Both infectious and noninfectious complication rates were higher in the groups receiving steroids. Patients who sustain a spinal cord injury secondary to a gunshot wound to the spine should not be treated with steroids until the efficacy of such treatment is proven in a controlled study.

An in vivo analysis of the dimensional changes of the neuroforamen after anterior cervical diskectomy and fusion: a radiologic investigation

Eighteen patients (11 men, 7 women; average age, 45.5 years) who underwent anterior cervical diskectomy and fusion (ACDF) for the treatment of radiculopathy had preoperative and immediate postoperative computed tomography (CT) scans to measure pre- and postoperative foraminal heights and foraminal areas, preoperative disk space height, and postoperative graft height. The mean foraminal height preoperatively was 0.851 cm; postoperatively, it was 1.01 cm, with a mean percentage increase of 20% (-8.8 to 56.8%). Mean preoperative foraminal area was 37.53 mm2, increasing to a mean of 49.04 mm2 postoperatively with a mean percentage increase of 33% (range, -1.5 to 76.9%). No significant correlations between graft height and change in maximal foraminal height or foraminal area or between changes in foraminal height or area and postoperative symptom relief were found. Although significant increases in foraminal dimensions were seen radiographically after ACDF, these increases were variable and not strongly related to graft height. In addition, the increases in foraminal dimensions were not related to the short-term clinical results of ACDF. This study fails to support the hypothesis that the reliable results of ACDF can be ascribed primarily to indirect decompression of the uncovertebral foramen by disk-space distraction.

Vertebral artery occlusion associated with cervical spine trauma. A prospective analysis

STUDY DESIGN

Radiographs and charts of 61 patients sustaining cervical spine trauma were studied prospectively to determine the incidence of vertebral artery injuries and possible correlative factors. Statistical analysis was conducted using chi-square testing of a two-way classification system.

OBJECTIVES

To elucidate the incidence of vertebral artery injuries associated with cervical spine trauma, and to determine the value of various factors in predicting the existence of a vertebral artery injury.

SUMMARY OF BACKGROUND DATA

During a 7-month period, 61 patients (41 male patients, 20 female; average age, 40.3 years) with cervical spine trauma were studied.

METHODS

All patients admitted to the authors' hospital with cervical spine injuries underwent magnetic resonance imaging and magnetic resonance angiography of their cervical spine. All magnetic resonance angiographies were examined for vertebral artery injury. Data on demographics and the injury were recorded.

RESULTS

Complete disruption of blood flow through the vertebral artery was demonstrated by magnetic resonance angiography in 12 of the 61 patients (19.7%). Ten of the 12 patients (83%) had either flexion distraction or flexion compression injuries. Age, sex, mechanism of injury, neurologic impairment, and associated injuries were not statistically significant in predicting the presence of a vertebral vessel occlusion.

CONCLUSION

The findings in this study may support the need for vertebral vessel evaluation in selective patients, particularly those with flexion injuries and with neurologic symptoms consistent with vertebral artery insufficiency syndrome that do not correlate with the presenting bone and soft-tissue injuries.

Surgical anatomy of the vertebral arteries

STUDY DESIGN

This study compared direct measurements of the distances between the vertebral arteries in the cervical spines of human cadaver specimens with data obtained from axial computed tomography images of these specimens.

OBJECTIVE

To determine whether the information obtained from a computed tomography scan can be used reliably to predict the true anatomic location of the vertebral arteries and, in so doing, provide accurate guidelines for the lateral extent of anterior cervical decompressive procedures.

SUMMARY OF BACKGROUND DATA

Iatrogenic vertebral artery injury during anterior cervical surgery is uncommon, potentially catastrophic, and avoidable.

METHODS

The means and standard deviation of measurements of the location of the cervical segment of the vertebral arteries obtained with high-precision, digital calipers by direct gross anatomic dissection of 16 adult (eight male, eight female) cadaver specimens were recorded. These measurements were compared with computed tomography scan data obtained on the same specimens.

RESULTS

The mean distances between the vertebral arteries progressively increased from C3 to C6. Computed tomography scan measurements of the distance between the cervical foramina transversaria were consistently smaller than direct measurements of the gross specimens. At C6, the computed tomography scan data were significantly less than the gross anatomic data.

CONCLUSIONS

According to these data, computed tomography scan measurements may be used safely and accurately to plan the lateral extent of anterior cervical decompressive surgical procedures. Although the data obtained from the gross anatomic dissections may serve as guidelines to assist the surgeon, the authors recommend a careful review of the preoperative computed tomography scan on an individual case-by-case basis as the safest method to plan for anterior cervical surgery.

Prenatal detection of fetal anomalies in pregnancies complicated by insulin-dependent diabetes mellitus

OBJECTIVES

We evaluated the clinical utility of a comprehensive program of prenatal diagnostic testing for congenital anomalies in pregnancies complicated by insulin-dependent diabetes mellitus.

STUDY DESIGN

Data were retrospectively analyzed from 289 diabetic women and their newborns from August 1987 to July 1993. Our protocol included initial hemoglobin A1 and maternal serum alpha-fetoprotein determinations and comprehensive fetal ultrasonography inclusive of a standard four-chamber view of the heart and detailed multiimage fetal echocardiography.

RESULTS

Anomalies were identified in 29 of 289 (10%) fetuses and neonates: 12 cardiac only, 14 noncardiac, and 3 combined. In 21 of the 29 (72%) neonates the anomalies were detected prenatally. Twelve of 15 (80%) cardiac and 10 of 17 (59%) noncardiac lesions were identified prenatally. Cardiac lesions, especially of the cardiac septum and great vessels, accounted for 50% of all fetal defects. Malformations of the neuroaxis, skeleton, and genitourinary system were also detected. There were six neonatal deaths and four therapeutic pregnancy terminations associated with congenital anomalies. Although the hemoglobin A1 level was statistically significantly increased in 22 mothers of anomalous fetuses (p = 0.017), the actual difference between affected and nonaffected pregnancies was not clinically meaningful and much overlap occurred. Although 96% of women with a normal hemoglobin A1 level were delivered of normal infants, only 14% of those with an elevated value had a malformed fetus. Similarly, although 89% of gravid women with a normal maternal serum alpha-fetoprotein level were delivered of nonaffected fetuses, only 7.3% of patients with an elevated value had a malformed fetus. For the detection of cardiac defects, the sensitivity of the four-chamber view compared with detailed multiimage fetal echocardiography was 33% and 92%, respectively.

CONCLUSIONS

This study demonstrates the utility of a comprehensive program to detect fetal anomalies in pregnancies complicated by diabetes mellitus.

Health outcome assessment before and after lumbar laminectomy for radiculopathy

STUDY DESIGN

Forty-one patients undergoing lumbar laminectomy for radiculopathy resulting from herniated discs assessed their health status using a generic health outcome instrument (Medical Outcomes Study Short Form 36) before surgery and at an average of 2 years after surgery.

OBJECTIVES

To assess whether lumbar laminectomy for herniated nucleus pulposus is a useful intervention when patients evaluate their own perception of health.

SUMMARY OF BACKGROUND DATA

The medical Outcomes Study Short Form 36 has been used in multiple studies assessing various medical conditions. It is brief, generic, and reliable. Although surgical treatment for radiculopathy by lumbar laminectomy has been shown to be successful using specific criteria for patient selection and an algorithmic approach, the authors are not aware of any study using a patient-based health outcome assessment to evaluate the results of this type of surgery.

METHODS

Forty-one patients (82% completed follow-up evaluation; average follow-up period, 2.08 years) completed Medical Outcomes Study Short Form 36 before and after surgery. Scores from before and after surgery were compared.

RESULTS

Statistically significant improvements (P < 0.01) were seen in eight of the nine health scores comparing scores from before and after surgery at follow-up evaluation. These included physical function, social function, role function resulting from physical limitations, role function resulting from emotional limitations, mental health, vitality, pain, and perceived health change. No significant change was seen in the patients' health perception after surgery.

CONCLUSIONS

This study shows that the patients' self-reported health outcomes after lumbar laminectomy correlate with the excellent results previously seen using physician-driven outcome measures in an appropriately selected population with radiculopathy. The excellent results shown here did not deteriorate with age (> 40 years compared with < 40 years) or with complications after surgery.

Health outcome assessment before and after adult deformity surgery. A prospective study

STUDY DESIGN

Fifty-five patients undergoing surgery for adult spinal deformity assessed their health status using a generic health outcome instrument before surgery and at an average of 2 years after surgery.

OBJECTIVE

To assess whether adult spinal deformity surgery is a useful intervention when patients evaluate their own perception of health. The Medical Outcomes Survey Short Form-36, a validated generic health outcome assessment form, was used to measure patient's health status.

SUMMARY OF BACKGROUND DATA

Surgery for adult scoliosis is technically demanding. No study that we are aware of uses a generic health outcome instrument in a prospective manner to compare patients' perception of their health after adult scoliosis surgery. The Medical Outcomes Survey Short Form-36 has been validated in multiple studies assessing other medical conditions and was found to be reliable, comprehensive, brief, and generic.

METHODS

Sixty-eight adult patients undergoing surgery for adult spinal deformity were prospectively enrolled. Fifty-five patients were available to complete the Medical Outcomes Surgery Short Form-36 after surgery. The scores of the health profile were compared before and after surgery. The results of patients younger than 40 years were compared with those of patients older than 40 years. The results of patients younger than 40 years were compared with those of patients older than 40 years. The results of patients fused to more caudal end vertebral levels ((L4, L5)5) were compared with those who were fused to more cranial end vertebral levels. The results of patients without complications after surgery were compared with those of patients with complications after surgery.

RESULTS

Average follow-up period was 22.5 months (minimum 12 months) in 82% of 68 patients. Statistically significant improvements were seen in postoperative scores for physical function, social function, bodily pain, and perceived health change. We found no significant differences in self-reported health function parameters related to age ( > 40 vs. < 40), end vertebral level of fusion, or presence of complications after surgery.

CONCLUSIONS

Applying a generic health outcome instrument to adult spinal deformity surgery shows that adult scoliosis surgery significantly improves patient self-reported health assessment and function. Beneficial results do not appear to deteriorate with age or more caudal end vertebral levels of fusion. Future studies combining disease-specific outcomes analysis and generic health surveys to assess end results of adult spinal deformity surgery will be useful.

Interleukin-1 beta regulates the inducible cyclooxygenase in amnion-derived WISH cells

The purpose of this study was to determine the mechanism of enhanced prostaglandin synthesis in amnion-derived WISH cell cultures when stimulated by interleukin-1 beta (IL-1 beta). Confluent monolayer cultures of WISH cells were incubated with human recombinant IL-1 beta (0.001-10 ng/ml) for 0-24 hours, while control cells received medium alone. PGE2 production was measured by specific radioimmunoassay. IL-1 beta enhanced the production of PGE2 in a dose- and time-dependent manner with enhanced production detectable by 2 h following exposure. Immunoblot analysis using isoform-specific antibodies showed that the inducible cyclooxygenase enzyme, i.e., COX-2, was expressed by 2 h in IL-1 treated cells, while the constitutive COX-1 remained unaltered in its expression. Northern blot analysis demonstrated that COX-2 mRNA expression was not detected in untreated cells, but became evident after a 30-min exposure to IL-1 beta (10 ng/ml). COX-1 mRNA was detected under basal conditions and did not increase significantly following IL-1 beta treatment. The close parallel between the kinetics of COX-2 mRNA and protein expression and PGE2 accumulation in the medium, as well as the constitutive, unregulated nature of the COX-1 isoform, indicates that cytokine-driven PGE2 formation in WISH cells may be mediated by de novo expression of the novel COX-2 enzyme.