Detection of low dose radiation induced DNA damage using temperature differential fluorescence assay.

A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposures of between 0.004 and 1 Gy were measured with doses as low as 0.008 Gy yielding significant responses. The double-strand, sensitive dye PicoGreen was used as an indicator of DNA denaturation. Calibration plots indicate that fluorescence changes corresponding to amounts as low as 1 ng of double stranded DNA (10(6) copies for plasmid puc 19) are detected by this method.

The Wiltse pedicle screw fixation system. Early clinical results.

Ninety-nine patients were studied prospectively after spine fusion augmented with the Wiltse pedicle screw fixation system. Follow-up ranged from 12 to 34 months, averaging 20 months. There were 33 men and 66 women. Their ages ranged from 20 to 86, with the average age of 52. This was the first spine surgery in 23 patients. Seventy-six patients had had prior spine surgery. Spine fusion was attempted at one to four levels of the lumbosacral spine. Major perioperative complications were seen in seven patients (7%). Hardware failure was seen in seven cases (7%). Union was assessed by radiographs at 1 year or more after surgery in 82 patients (85%). In those 82 patients, union was seen in 56 (68%) and nonunion in 26 (32%). Change in lordosis was measured in 54 patients. The average change was a loss of 1.7 degrees lordosis per level fused. A questionnaire was answered by 79 patients (81%). Overall, 55 (70%) stated that they had some benefit from surgery, ten (13%) had no change, and 13 (17%) were worse.

New uses and refinements of the paraspinal approach to the lumbar spine.

The paraspinal approach was described by our group in 1968. It differs from the approach described by Melvin Watkins in 1953 in that it is a longitudinal separation of the sacrospinalis group between the multifidus and longissimus, and not between the lateral border of the entire sacrospinalis group and quadratus lumborum. Also, Watkins removed a flake of the iliac crest with muscles attached, which he swung cranially and medially. This article also describes several refinements not mentioned in the original article and gives several new uses for the approach. Specifically, its use for removing a far lateral disc, decompressing a far out syndrome, inserting pedicle screws, and for decompressing the opposite side from inside the vertebral canal is described.

Chemonucleolysis. A ten-year retrospective study.

An 11.8-year median follow-up evaluation of 42 "ideal" patients who had chemonucleolysis was obtained by examination, questionnaire, and roentgenograms. The excellent and good rating of this group was 81%, as compared to the total of 135 patients previously evaluated at 42 months and showing 85.2%. No complications were noted. Disc space rewidening, after initial narrowing, was observed in eight patients and 26% of all discs injected. While all who showed rewidening had excellent results, widening was not necessary to achieve an excellent rating. Marked narrowing and sclerosis of intervertebral margins were seen in many excellent and good clinical results. Chemonucleolysis represents a viable option as definitive treatment for a herniated nucleus pulposus in carefully selected patients.

Dorsolumbar kyphosis or Scheuermann's disease.

Confusion over dorsolumbar kyphosis and Sheuermann's disease has existed in the literature since the first recorded episodes in 1921. The present article delineates an etiology of back pain that is frequently seen in the adolescent population and is not to be confused with the painless fixed kyphotic deformity so frequently mentioned in the scoliosis literature. These patients with a painful dorsolumbar Sheuermann's disease may well have a traumatic herniation of the disk into the bony vertebral body. This type of x-ray and clinical finding should become familiar to all clinicians dealing with an adolescent population.

A biomechanical study of intrapeduncular screw fixation in the lumbosacral spine.

This laboratory experiment was undertaken to identify factors contributing to intrapeduncular screw fixation in the vertebra. Testing was performed in axial pull-out and cyclic loading modes using multiple screw designs inserted to various depths into fresh human lumbosacral vertebra. The degree of osteoporosis played a major role in pull-out strength. Larger diameter, full-threaded screws inserted deep enough to engage the anterior vertebral cortex resulted in the most secure fixation. In the sacrum, the second sacral pedicle was the weakest location of insertion. Screws aimed laterally into the ala at 45 degrees or medially into the first sacral pedicle resisted larger axial pull-out loads than those inserted straight anteriorly into the ala. Methyl methacrylate was found to restore secure fixation in previously-loosened screws and pressurization of cement doubled the pull-out force. In cyclic load tests, deeper-inserted screws were found to withstand a greater number of cycles before loosening. Measurements of pedicle outer cortical diameters were found in many specimens to be smaller than both the 4.5-mm and 6.5-mm diameter screws.

Alar transverse process impingement of the L5 spinal nerve: the far-out syndrome.

This syndrome occurs in two types of patients: (1) the elderly person with degenerative scoliosis and (2) a somewhat younger adult population with isthmic spondylolisthesis and at least 20% slip. On plain radiograph, the Ferguson view (25 degrees caudocephalic) is best for visualizing the condition, however, CT is by far the best diagnostic tool. To show this far laterally, the "window" on the CT scanner must be opened wider than usual. Both coronal and parasagittal views will demonstrate the condition, but the coronal is the most valuable. Symptoms are classical spinal nerve compression. Usually it is the L5/S1 level that is involved, but other levels can be. At surgery, it is most important that nerve decompression be carried far enough laterally. This can mean sacrificing the lower half of the pedicle and the entire transverse process. Part of the body of S1 and of the sacral ala can be removed if the surgeon prefers. Because so much bone is removed, instability is a factor to be seriously considered. How to decompress adequately and still maintain stability often poses a most difficult problem.

Back injuries in the athlete.

In summary, the approach to the athlete with low back pain must include an emphasis on aggressive nonoperative intervention, education, and rehabilitation. A diligent attempt must be made to establish a correct diagnosis, though this may be difficult at first. A firm diagnosis allows individualized treatment that meets the strenuous needs of the athlete. Work-up should be standardized to avoid missing what will appear obvious in retrospect. Unlike most of the general patient population, athletes are unlikely to tolerate a long period of "wait and see" therapy. It is necessary to have qualified allied health personnel who can perform a full spectrum to have qualified allied health personnel who can perform a full spectrum of exercise, mobilization, and modality therapies. Return to competition should be gradual but steady, as previous performance levels can usually be obtained following lumbar injuries.

Chemonucleolysis under local anesthesia.

A protocol for performing lumbar disc chemonucleolysis under local anesthesia is presented. Advantages are discussed, including early detection and management of anaphylaxis and shortened procedure time.