Kevin F. Spratt

Classification of age-related changes in lumbar intervertebral discs. 2002 Volvo Award in basic science

Study Design. A histologic study on age-related changes of the human lumbar intervertebral disc was conducted. Objectives. To investigate comprehensively age-related temporospatial histologic changes in human lumbar intervertebral disc, and to develop a practicable and reliable classification system for age-related histologic disc alteration. Summary of the Background Data. No comprehensive microscopic analysis of age-related disc changes is available. There is no conceptual morphologic framework for classifying age-related disc changes as a reference basis for more sophisticated molecular biologic analyses of the causative factors of disc aging or premature aging (degeneration). Methods. A total of 180 complete sagittal lumbar motion segment slices obtained from 44 deceased individuals (fetal to 88 years of age) were analyzed with regard to 11 histologic variables for the intervertebral disc and endplate, respectively. In addition, 30 surgical specimens (3 regions each) were investigated with regard to five histologic variables. Based on the semiquantitative analyses of 20,250 histologic variable assessments, a classification system was developed and tested in terms of validity, practicability, and reliability. The classification system was applied to cadaveric and surgical disc specimens not included in the development of the classification system, and the scores were assessed by two additional independent raters. Results. A semiquantitative analyses provided clear histologic evidence for the detrimental effect of a diminished blood supply on the endplate, resulting in the tissue breakdown beginning in the nucleus pulposus and starting in the second life decade. Significant temporospatial variations in the presence and abundance of histologic disc alterations were observed across levels, regions, macroscopic degeneration grades, and age groups. A practicable classification system for age-related histologic disc alterations was developed, resulting in moderate to excellent reliability (&kgr; values, 0.49–0.98) depending on the histologic variable. Application of the classification system to cadaveric and surgical specimens demonstrated a significant correlation with age (P < 0.0001) and macroscopic grade of degeneration (P < 0001). However, substantial data scatter caution against reliance on traditional macroscopic disc grading and favor a histology-based classification system as a reference standard. Conclusions. Histologic disc alterations can reliably be graded based on the proposed classification system providing a morphologic framework for more sophisticated molecular biologic analyses of factors leading to age-related disc changes. Diminished blood supply to the intervertebral disc in the first half of the second life decade appears to initiate tissue breakdown.

Long-term follow-up of lower lumbar fusion patients.

To determine the long-term effects of lower lumbar fusion, 94 subjects were catalogued from medical records. They had a lumbar arthrodesis at the third lumbar level or below and their operations were performed before 1964. Twenty-four were not located and 8 were deceased. Sixty-two subjects (72% of available sample) completed a telephone interview; 52 subjects completed a comprehensive low back questionnaire; and 33 subjects returned for physical examination, flexion–extension lateral lumbar spine films, and a limited computerized axial tomographic (CAT) scan. In general, the subjects who returned for complete evaluation were representative of the larger sample. Forty of 62 patients were men. Ages ranged from 41 to 83 years; the median age was 66 years, 6 months. Follow-up ranged from 21 to 52 years; the median follow-up was 33 years. Forty-four percent (27/61) were currently experiencing low-back pain, 57% (35/61) had back pain in the last year. Fifty-three percent (33/62) were using medication. Fifteen percent (9/62) had undergone repeat lumbar surgery, however, only 5% (3/62) required surgery as a late sequela (more than 10 years postoperatively). Forty-two percent (14/33) had lumbar spinal stenosis, but only 15% (5/33) had dural tube measurements less than 100 mm2. Segmental instability above the fusion was present in 45% (15/33). There was a significant correlation between segmental instability and lumbar spinal stenosis (r =.57, P <.01). Neither radiographic condition correlated with symptoms, however. Patients fused for spondylolysis and spondylolisthesis were likely to report incidence of pain and reported less severe pain than patients fused for other reasons (P <.01 and <.10, respectively). There was no significant difference in the disability assessments between these surgical subgroups. Although patients after lower lumbar fusion report more pain than the general population and have more radiographic evidence of instability and stenosis than expected for the general population, they are generally doing well and are satisfied with the results of their surgery.

The diagnostic accuracy of magnetic resonance imaging, work perception, and psychosocial factors in identifying symptomatic disc herniations

Study Design This was a prospective study of patients (study group) with symptomatic disc herniations and asymptomatic volunteers (control group) matched for age, sex, and work-related risk factors. Objective To determine the prevalence of disc herniation in a matched group of asymptomatic volunteers and to access the diagnostic accuracy of magnetic resonance imaging, work perception, and psychosocial factors in identifying symptomatic disc herniations. Summary of Background Data Disc herniations have been reported to occur in 20–36% of asymptomatic volunteers. A valid comparison of asymptomatic individuals and patients with disc herniations has not been performed. Methods Forty-six patients with low back pain and sciatica severe enough to require a disceclomy were compared with 46 age-, sex-, and risk factor-matched (heavy lifting, twisting and bending, vibration, and sedentary activity) asymptomatic voluteers. Both groups had a complete clinical and magnetic resonance imaging examination and completed a questionnaire to assess differences in the psychosocial and work perception profiles. The prevalence and the severity of morphologic alterations (disc herniation, disc degeneration, and neural compromise) was analyzed by two independent radiologists in a blinded fashion. Differences between both groups regarding MRI findings, work perception (occupational mental stress, intensity of concentration, job satisfaction, and job-related resignation) and psychosocial factors (anxiety, depression, self-control, social support, and marital status) were compared using multivariate techniques. Stepwise discriminate analysis was used to identify the best discriminating variables within the magnetic resonance image, work perception, and psychosocial categories in terms of the diagnostic accuracy to predict group membership (study [pain] or control [no pain] group). Results Matched controls had significantly more risk factors than a group of normal individuals. The present study has presented evidence that an age-, gender-, and occupational risk factors-matched group of asymptomatic patients shows a high incidence rate of disc herniations (76%). Although significantly less than the symptomatic group incidence of 96%, this represents a much higher prevalence rate than generally expected and reported in other studies of unmatched asymptomatic volunteers. Patients had more severe disc herniations (disc extrusions) than asymptomatic volunteers (35% vs. 13%). There was no significant differences regarding disc degeneration between both groups (96% vs. 85%). The only substantial morphologic difference between both groups was the presence of a neural compromise (83% vs. 22%), which was highly significant (P < 0.0001). There were significant differences between both groups regarding work perception (occupational mental stress, intensity of concentration, job satisfaction, and resignation; P<0.027) and psychosocial factors (anxiety, depression, self-control, marital status; P<0.0001). The best single predictor of a group membership was the extent of neural compromise. A combination of this factor with occupational mental stress, depression, and marital status was the best predictive model. With this model, the false-negative rate (potential overtreatment of disc morphology) was reduced by more than half compared with morphologic factors (nerve root compression) alone (22% vs. 11%). Conclusions. In an age-, sex-, and risk factormatched group of asymptomatic individuals, disc herniation had a substatially higher prevalence (76%) than previously reported in an unmatched group. Individuals with minor disc herniations (i.e., protrusion, contained discs) are at a very high risk that their magnetic resonance images are not a causal explanation of pain because a high rate of asymptomatic subjects (63%) had comparable morphologic findings. The only highly significant difference between the study group and control group regarding morphologic findings was the criteria of a nerve root compromise. Work perception and psychosocial factors were helpful in discriminating between symptomatic and asymptomatic disc herniations.

Spinal pedicle fixation: reliability and validity of roentgenogram-based assessment and surgical factors on successful screw placement.

The increased popularity of pedicle fixation prompted research to address two issues: the reliability and validity of roentgenograms as a technique for evaluating the success of pedicle fixation, and the effects of surgical factors on successful fixation. Thus, does approach—the point and angle of screw insertion, surgeon experience, practice, level of the spine involved, and screw size—effect success of pedicle fixation? Eight fresh thoracolumbar spines were harvested and cleaned of all soft tissues. Two surgeons, one more experienced in pedicle fixation than the other, used two pedicle fixation approaches (Weinstein and Roy-Camille) on both the left and right sides at levels T11–S1 of each specimen. All screws were placed under anteroposterior (AP) and lateral c-arm control. For specimens 1 to 3, 5.5 mm screws were used at T11–L1, and 7.0 mm screws at L2–S1. Unacceptable failure rates at L2 and L3 for the first three specimens resulted in a change of instrumentation for the remaining specimens, with 5.5 mm screws used at T11–L3 and 7.0 mm screws at L4–S1. When surgeons completed the fixations for a specimen, AP and lateral roentgenograms were taken and both surgeons independently evaluated the films to assess the success of each fixation. Failure was defined as evidence of any cortical perforation on any side of the pedicle in or outside of the spinal canal. After completing the roentgenogram evaluation, the specimen was transected in the midline, and the success of each pedicle fixation was evaluated by visual/tactile inspection. There were no disagreements between surgeons on the visual/tactile evaluations of the specimens. In contrast, inter-rater adjusted percent agreement for roentgenograms ratings was 74, judged to be less than satisfactory when considering that the ratings were on a 2-point scale (S or F). The overall failure rate was approximately 21% (26/124). Of the 26 failures, 92% represented cortical perforations within the spinal canal. Discrepancies between visual/tactile and roentgenogram-based evaluations were not encouraging. Occurrence of false-positive results was at rates of 8.1% and 6.5%, and false-negative results occurred at a rate of 14.5% amd 12.9% for the more and less experienced surgeons, respectively. In general, success rate was independent of surgical factors. Success was not significantly related to approach, surgeon experience, screw size, or spine level. There was, however, an appreciable practice effect, χ2 = 8.84, P < 0.003. Failure rates were 26.4% compared to 6.4% for specimens 1–4 and 5–8, respectively. Also of interest was a trend for success to be related to approach, depending on the region of the spine involved, F1,100=3.38, P<0.07. Examination of relative success rates indicated no significant differences between the Weinstein and Roy-Camille approach in the upper lumbar spine (T11–L2), but a trend toward greater success with the Weinstein approach in the lower lumbar spine (L3–S1); a 93.1% success rate for the Weinstein, compared with 78.6% for the Roy-Camille approach. Roentgenograms were found to produce unacceptably high rates of false-positive and false-negative evaluations. The lack of differences in success rates between the surgeons with different levels of experience in conjunction with a strong relationship between success rate and practice is consistent with poor roentgenogram evaluation. Surgeons cannot be expected to improve with experience when their tools (roentgenograms) do not allow accurate evaluation of their performance. However, significant improvement in success rate can be expected when accurate evaluation is provided. Unfortunately, this research exposes the inadequacies of current evaluation procedures without providing viable alternatives. The trend toward superior success rates with the Weinstein approach in the lower lumbar spine is particularly important since the approach is believed to have the added advantage of providing less interference with uninvolved adjacent motion segments. Such an advantage would be of little value if the success rate was not at least as good as demonstrated for other approaches.

Pain intensity assessment in older adults: Use of experimental pain to compare psychometric properties and usability of selected pain scales with younger adults

Objectives:To determine: (1) the psychometric properties and utility of 5 types of commonly used pain rating scales when used with younger and older adults, (2) factors related to failure to successfully use a pain rating scale, (3) pain rating scale preference, and (4) factors impacting scale preference. Methods:A quasi-experimental design was used to gather data from a sample of 86 younger (age 25–55) and 89 older (age 65–94) adult volunteer subjects. Responses of subjects to experimentally induced thermal stimuli were measured with the following pain intensity rating scales: vertical visual analog scale (VAS), 21-point Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), 11-point Verbal Numeric Rating Scale (VNS), and Faces Pain Scale (FPS). Results:All 5 pain scales were effective in discriminating different levels of pain sensation; however the VDS was most sensitive and reliable. Failure rates for pain scale completion were minimal, except for the VAS. Although age did not impact failure to properly use this pain intensity rating scale, but rather those conditions more commonly associated with advanced age, including cognitive and psychomotor impairment did. The scale most preferred to represent pain intensity in both cohorts of subjects was the NRS, followed by the VDS. Scale preference was not related to cognitive status, educational level, age, race, or sex. Conclusion:Although all 5 of the pain intensity rating scales were psychometrically sound when used with either age group, failures, internal consistency reliability, construct validity, scale sensitivity, and preference suggest that the VDS is the scale of choice for assessing pain intensity among older adults, including those with mild to moderate cognitive impairment.

The natural history and long-term follow-up of Scheuermann kyphosis.

Sixty-seven patients who had a diagnosis of Scheuermann kyphosis and a mean angle of kyphosis of 71 degrees were evaluated after an average follow-up of thirty-two years (range, ten to forty-eight years) after the diagnosis. All sixty-seven patients completed a questionnaire; fifty-four had a physical examination and radiographs; fifty-two, pulmonary function testing; and forty-five, strength-testing of the trunk muscles. The results were compared with those in a control group of thirty-four subjects who were matched for age and sex. The patients who had Scheuermann kyphosis had more intense back pain, jobs that tended to have lower requirements for activity, less range of motion of extension of the trunk and less-strong extension of the trunk, and different localization of the pain. No significant differences between the patients and the control subjects were demonstrated for level of education, number of days absent from work because of low-back pain, extent that the pain interfered with activities of daily living, presence of numbness in the lower extremities, self-consciousness, self-esteem, social limitations, use of medication for back pain, or level of recreational activities. Also, the patients reported little preoccupation with their physical appearance. Normal or above-normal averages for pulmonary function were found in patients in whom the kyphosis was less than 100 degrees. Patients in whom the kyphosis was more than 100 degrees and the apex of the curve was in the first to eighth thoracic segments had restrictive lung disease. Five patients had an unexplained, mildly abnormal neurological examination. Mild scoliosis was common; spondylolisthesis was not observed.

Thoracolumbar burst fractures : the clinical efficacy and outcome of nonoperative management

There continues to be considerable controversy regarding the management of thoracolumbar burst fractures. Most feel that failure of the middle osteoligamentous complex, particularly with retropulsion of fragments into the spinal canal, is an indication for operative management. Others advocate postural reduction and prolonged bedrest for such injuries. The purpose of this study was to 1) review the clinical outcome and efficacy of closed management of thoracolumbar burst fractures; and 2) quantify what, if any, remodeling occurs in the bony canal as measured by serial CT. Forty-one patients who presented with a burst fracture of the thoracolumbar spine without neurologic deficit were reviewed clinically and radiographically following nonoperative management. At injury, canal compromise averaged 37% (range, 16-66%); 26 patients had at least 30% canal compromise. During treatment, one patient developed neurologic deterioration that prompted surgery; all other patients remained neurologically intact. At average follow-up of 2 years, an overall outcome evaluation indicated that 49% of the patients had excellent outcomes relative to pain and function; 17%, good; 22%, fair; and 12%, poor. Approximately 90% of the patients had a satisfactory work status relative to factors associated with their burst fracture. Serial roentgenograms documented significant progression in body collapse, which averaged 8% (P < 0.0001) from injury to follow-up. On the other hand, serial CTs documented significant improvement from injury to follow-up for canal compromise and midsagittal diameter. Average improvements in canal compromise and midsagittal diameter were 22% (P < 0.0001) and 11% (P < 0.0001), respectively. Only three patients had canal compromise greater than 30%, no patients had canal compromise greater than 40%, and no patients experienced canal area deterioration over time. On average, nearly two-thirds of the fragment occluding the canal resorbed, with most remodeling complete within one year. For patients with burst fractures presenting neurologically intact, we obtained the following findings: 1) nonoperative management yields acceptable results; 2) following nonoperative management, bony deformity (i.e., kyphosis and body collapse) progresses marginally relative to the rate of canal area remodeling; 3) incidence of subsequent neurologic deficits is quite low; and 4) initial radiographic severity of injury or residual deformity following closed management does not correlate with symptoms at follow-up. This pattern of results suggests nonoperative management as the preferred treatment in these circumstances.

Muscular Response to Sudden Load: A Tool to Evaluate Fatigue and Rehabilitation

Study Design Subjects were exposed to fatiguing and restorative interventions to assess their response to sudden loads. Objectives To investigate the erector spinae and rectus abdominis response characteristics to “sudden load” and the effect of fatigue and rehabilitation. Summary of Background Data Unexpected loads, which people often experience, can lead to high forces in the spine and may be a cause of low back injury. Methods Muscle responses to sudden load were mediated by fatigue, walking, expectation, method of load application, exposure to vibration, and cognitive‐behavioral rehabilitation in patients with chronic low back pain. A novel technique, perfected in this work, called wavelet analysis, was used to analyze these data. Results Reaction time was affected by fatigue and expectation. Vibration exposure significantly increased the muscle response time. Walking was able to ameliorate that effect. Back muscles responded differently, depending on whether loads were applied to the back through the hands or through the trunk. Electromyographic reaction time and magnitude decreased in patients after a 2‐week rehabilitation program. Conclusions Sudden loads can exacerbate fatigue effects. Walking after driving reduces the risk to the back caused by handling unpredictable loads. Vibration exposure guidelines should be more conservative. Patients have longer response times than healthy subjects, but patients can improve their response to sudden loads via rehabilitation. Patients exhibit a flexion‐extension oscillation at 5 Hz in response to a sudden load, suggesting that the 5‐Hz, seated, natural frequency observed during whole‐body vibration may result from neurophysiologic control limits.

Outcome measures for studying patients with low back pain

There is growing recognition in the treatment of back pain that patient perapectives are essential in judging the results of treatment. Improving the patients “quality of life” is often the main goal of therapy. Thus, although clinical research in the past has focused on physiologic outcomes, such as range of motion, muscle strength, or neurologic deficits, increasing attention is being given to the rigorous measurement of symptoms, functional status, role function, satisfaction with treatment, and health care costs. In many cases, these so called “soft” outcomes can be measured with a level of reproducibility similar to more conventional clinical data such as imaging test results. Because symptoms and functional outcomes are sometimes only loosely associated with physiologic phenomena, the former outcomes should be measured directly. Modern questionnaires for measuring patient quality of life combine the expertise of social scientists and clinicians and have demonstrated validity. Furthermore, they have some important advantages over simple ratings of “excellent, good fair, and poor” outcomes, or work status alone, Several modern instruments for measuring health-related-quality of life in patients with low back pain are reviewed briefly, describing their content and length. Wlder use of these instruments would help to increase clinician familiarity with their meaning and avoid duplication of effort in questionnaire development.

The role of steroids and their effects on phospholipase A2. An animal model of radiculopathy.

Study Design. The possible role of phospholipase A2 in an animal model for lumbar radiculopathy and mechanisms of epidural steroid injections were studied. Objectives. To clarify the pathophysiologic mechanism of the recently proved animal model for lumbar radiculopathy and to characterize further the mechanisms of action of steroids. Summary of Background Data. There have been several reported animal models of peripheral neuropathy. Recently an animal model that shows reliable behavioral and neurochemical changes was proposed, and epidural steroid injections in this model were effective in the reduction of thermal hyperalgesia and allodynia. Method. In a behavioral study, 24 rats were divided into 4 groups: Group I, loose ligature of the left L4 and L5 nerve roots with 4‐0 chromic gut sutures and an epidural injection of 0.1 mL of saline at 3 days after surgery; Group II, same as Group I but with an epidural injection of 0.1 mL of betamethasone on the day before the operation; Group III, same as Group II except injection at 1 day after surgery; Group IV, same as Group II except injection at 3 days after surgery. To test the phospholipase A2 activity in the nerve roots and dorsal root ganglia after the operation, eight rats were killed at given intervals. Analysis of variance techniques were used to test behavioral pattern changes and phospholipase A2 activity across time in each group. Results. Thermal hyperalgesia reached its maximal point at 3 weeks after surgery in Group I, but in steroid injection groups, the recovery from hyperalgesia was faster than in Group I. However, there was no significant difference in recovery time among steroid injection groups. The level of phospholipase A2 activity was at its maximum at 1 week after surgery in Groups I and IV. It showed a steady reduction in the steroid group, whereas it remained relatively high and dropped rapidly after 3 weeks in the saline‐treated group, and returned to the level of a normal nerve root at 6 weeks after surgery. Conclusion. These results suggest that the behavioral pattern changes observed in the irritated nerve root model are caused in part by a high level of phospholipase A2 activity initiated by inflammation, and that the mechanism of action of epidural steroid injection in this model is inhibition of phospholipase A2 activity.