Robert G. Watkins

Magnetic resonance imaging in the diagnosis of disc degeneration: correlation with discography.

One hundred and one disc levels in 36 patients with low-back pain were studied with magnetic resonance imaging (MRI) (T2-weighted) sagittal images and conventional roentgenographic discography to detect early disc degeneration. Thirty-nine discs also were evaluated after discography with roentgenographic CT MRI findings were compared with discography results. MRI was 99% accurate in predicting normality or abnormality as determined by discography. Changes in disc signal on MRI accurately reflected the presence or absence of degenerative changes seen on discography in patients with low-back pain. Clinically, MRI is a useful technique for detecting early disc degeneration and for assessing the affected disc level and adjacent levels in patients with low-back pain and spondylolithesis.

Comparison of disc space heights after anterior lumbar interbody fusion

Thirty-one consecutive patients underwent anterior interbody fusion of 40 levels of the lumbar spine using autogenous, autologous, or mixed iliac crest graft. Each patients disc space height was measured preoperatively, immediately postoperatlvely, and an average of 29 months postoperatively. The immediate postoperative radiograph demonstrated an average Increase in disc space height of 89%, or 9.5 mm for each operated level. The late radiographic evaluation, from 7 to 54 months postoperatively, showed an average decrease of 1%, or 0.1 mm for each level. At late follow-up, no correlation could be found between the time from the operation and disc space height. One hundred percent of patients developed disc space height decreases during the postoperative period, with 46% of levels being narrower than their preoperative height at last follow-up. Loss of distraction is a normal postoperative occurrence of the procedure. Disc space distraction is temporary with anterior interbody fusion.

Lumbar Lordosis: Effects of Sitting and Standing

Study Design. The effect of sitting versus standing posture on lumbar lordosis was studied retrospectively by radiographic analysis of 109 patients with low back pain. Objective. To document changes in segmental and total lumbar lordosis between sitting and standing radiographs. Summary of Background Data. Preservation of physiologic lumbar lordosis is an important consideration when performing fusion of the lumbar spine. The appropriate degree of lumbar lordosis has not been defined. Methods. Total and segmental lumbar lordosis from L1 to S1 was assessed by an independent observer using the Cobb angle measurements of the lateral radiographs of the lumbar spine obtained with the patient in the sitting and standing positions. Results. Lumbar lordosis averaged 49° standing and 34° sitting from L1 to S1, 47° standing and 33° sitting from L2 to S1, 31° standing and 22° sitting from L4 to S1, and 18° standing and 15° sitting from L5 to S1. Conclusion. Lumbar lordosis while standing was nearly 50% greater on average than sitting lumbar lordosis. The clinical significance of this data may pertain to: 1) the known correlation of increased intradiscal pressure with sitting, which may be caused by this decrease in lordosis; 2) the benefit of a sitting lumbar support that increases lordosis; and 3) the consideration of an appropriate degree of lordosis in fusion of the lumbar spine.

Dynamic Electromyographic Analysis of Trunk Musculature in Professional Golfers

Using dynamic surface electrode electromyography, we evaluated muscle activity in 13 male professional golfers during the golf swing. Surface electrodes were used to record the level of muscle activity in the right abdominal oblique, left abdominal oblique, right glu teus maximus, left gluteus maximus, right erector spi nae, left erector spinae, upper rectus abdominis, and lower rectus abdominis muscles during the golfers swing. These signals were synchronized electronically with photographic images of the various phases of the golf swing; the images were recorded in slow motion through motion picture photography. The golf swing was divided into five phases: take away, forward swing, acceleration, early follow-through, and late fol low-through. Despite individual differences among the subjects swings, we observed reproducible patterns of trunk muscle activity throughout all phases of the golf swing. Our findings demonstrate the importance of the trunk muscles in stabilizing and controlling the loading response for maximal power and accuracy in the golf ers swing. This study provides a basis for developing a rehabilitation program for golfers that stresses strengthening of the trunk muscles and coordination exercises.

Dynamic EMG analysis of Torque transfer in professional baseball pitchers

Fifteen professional baseball pitchers underwent active pitching motion analysis of the abdominal oblique, rectus abdominis, lumbar paraspinous and gluteus maximus muscles bilaterally via surface electrode evaluation. Baseline resting and isometric maximum values were obtained and active data referenced against these for comparison. The muscle activity then was measured during the pitching sequence and analyzed in each of the five pitching phases. The abdominal oblique, lumbar paraspinous and rectus abdominis contralateral to the pitching arm and the ipsilateral gluteus maximus all had increases in activity level of 75 to 100% during the active pitching motion. Using these data indicating specific muscle group patterns with clinical and performance data, we hope to minimize injuries and maximize pitching performance.

Comparison of MRI to contrast CT in the diagnosis of spinal stenosis

Retrospectively, the MR (magnetic resonance) and contrast CT (computed tomography examinations of 41 patients (123 segments) were objectively scored to evaluate spinal stenosis and disc degeneration. Five categories to evaluate stenosis included the facet joint, foramina, central canal, disc on sagittal section, and disc on axial section. In addition, the ability to demonstrate spondylolysis was compared. The examinations were interpreted by a single observer blinded to the results. Comparisons show 96.6% agreement between MR and contrast CT in the diagnosis of spinal stenosis. Magnetic resonance showed disc degeneration in 74 of 123 segments, while CT showed disc degeneration disease in 27 of 123 segments. Spondylolysis was recognized at three segments on both MR and CT. In conclusion, MR and contrast CT are comparable in their abilities to demonstrate spinal stenosis, and MR is more sensitive in demonstrating disc degeneration.

Incidence of cervical spinal stenosis in professional and rookie football players

Sagittal canal/vertebral body ratios were measured on cervical spine lateral radiographs of 124 professional football players and 100 rookie football players. A total of 894 levels were measured in 224 players. Thirty-two percent (40) of the 124 professional football players, and 34% of the 100 rookies had a ratio of less than 0.80 at one or more levels from C3 to C6. The 0.80 ratio has been considered indicative of cervical spinal stenosis. This is the first time that the incidence of spinal stenosis, as determined by Torgs ratio, has been dem onstrated in a population of professional and rookie football players. Because one-third of this population has cervical spinal stenosis as determined by the Torg ratio, other factors should be considered in the evalu ation of a player with a transient quadriplegic episode when making continued play decisions.

Lumbar lordosis in spinal fusion. A comparison of intraoperative results of patient positioning on two different operative table frame types.

Study Design One hundred one patients undergoing spine surgery for degenerative conditions were entered into a prospective radiographic evaluation of changes in lumbar lordosis as affected by positioning on two different operative tables. Objectives The hypothesis of the present study is twofold: 1) the positioning of patients on specific types of operative tables may affect significantly the overall degree of lumbar lordosis obtainable, and 2) certain operative positioning may more accurately reproduce physiologic standing lateral lumbar lordosis. Summary of Background Data In the management of degenerative and post‐traumatic spinal deformities, lumbar fusion using posterior instrumentation permits more accurate and physiologic lordotic positioning of the involved fusion segments of the lumbar spine. However, various types of operating frames are available for use in this type of surgery, and despite the overall importance of correct lordotic positioning, there is some question as to what effect on positioning, as measured in degrees of lumbar lordosis, a particular frame might have. Methods Total, multisegmental, and unisegmental Cobb angle measurements of preoperative standing lateral radiographs and intraoperative lateral radiographs after positioning on respective operative tables were determined. Fifty‐one patients were positioned on an Andrews‐type table, and 50 patients were positioned on the four‐poster‐type frame. Statistical comparison using analysis of variance testing of changes in lordosis before and after surgery between study groups was evaluated. Results Lumbar lordosis measured from L1 to S1 with standing lateral radiographs showed a combined mean preoperative measurement of 45.18°, with no statistical significance between groups. In comparison, there was a statistically significant difference between intraoperative measurements from L1 to S1 on the Andrews table versus the four‐poster frame, revealing an average of 32.81° versus 47.71°, respectively (P < 0.005). Multisegmental lordosis measurement from L2 to S1 displayed statistical significance between groups, with a combined preoperative standing lateral radiograph average of 43.32°, and intraoperative values of 31.28° on the Andrews table versus 45.34° on the four‐poster frame (P < 0.005). Multisegmental lordosis measurements from L4 to S1 displayed statistical significance between groups, with a combined preoperative standing lateral radiograph average of 31.40° and intraoperative values of 23.14° on the Andrews table versus 32.94° on the four‐poster frame (P < 0.005). Segmental lordosis at L5‐S1 was less dependent on frame type, with a combined preoperative standing lateral radiograph average of 20.53° and intraoperative measurements of 20.06° on the Andrews table versus 21.02° on the four‐poster frame (P < 0.43). Conclusion Results from the present study display a statistically significant difference between multisegmental and total lumbar lordosis, depending on the type of operative table used in patient positioning. Segmental lordosis at L5‐S1 depended less on frame type. This table‐dependent positional change in lumbar lordosis could be incorporated easily into a lumbar fusion procedure, especially when supplemented with instrumentation, affecting the permanent overall degree of lordosis. These results suggest that a more physiologic degree of lumbar lordosis is obtained accurately with use of an operative table similar to the four‐poster frame.

The role of spinal flexion and extension in changing nerve root compression in disc herniations

Changes in nerve root compression forces with spinal motion were measured on six freshly frozen adult cadaver spine specimens. A model was devised to represent a herniated disc at the L4-5 level. This was done using an anterior approach placing a compressionmeasuring device through the disc at the L4-5 level and against the L5 root. An accelerometer was used to monitor the range of motion of the spine. Because the compression device was held in a static position, the only variable was the tautness of the nerve root across the tip of the device. By simultaneously monitoring motion and force delivered at the tip of the compression meter placed at the nerve root, we were able to quantitate nerve root tension forces across the tip of the measuring device in relation to spinal motion. The force was measured with controls as well as in flexion and extension. In addition, the force was measured as traction was applied to the L5 root. The amount of compressive force and tension in the nerve root increased with flexion of the spine and decreased with extension of the spine. In conclusion, flexion of the lumbar spine increased the compressive force on the L5 root and extension decreased the compressive force on the L5 root.

Comparisons of Preoperative and Postoperative Mmpi Data in Chronic Back Patients

The purpose of this study was to analyze 42 patients disabled with low-back pain in order to assess (1) Minnesota Multiphasic Personality Index (MMPI) changes before and after surgery, (2) the predictive value of MMPI, (3) the results of anterior lumbar fusion in one group of severely disabled lumbar low-back pain patients. Statistical analyses were performed to compare and contrast MMPI, pain assessment, functional and occupational levels, and disability index before and after surgery. The degree of morbidity of the patients preoperatively was severe. After surgery, the majority of the patients showed improvement in their overall status. The available evidence suggests the following: (1) Improvement in physical condition can produce improvement in psychological test scores; (2) The preoperative MMPI is not a reliable indicator of surgical success.