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 degrees standing and 34 degrees sitting from L1 to S1, 47 degrees standing and 33 degrees sitting from L2 to S1, 31 degrees standing and 22 degrees sitting from L4 to S1, and 18 degrees standing and 15 degrees 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 gluteus maximus, left gluteus maximus, right erector spinae, left erector spinae, upper rectus abdominis, and lower rectus abdominis muscles during the golfer's 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 follow-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 golfer's swing. This study provides a basis for developing a rehabilitation program for golfers that stresses strengthening of the trunk muscles and coordination exercises.

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 degrees, 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 degrees versus 47.71 degrees, 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 degrees, and intraoperative values of 31.28 degrees on the Andrews table versus 45.34 degrees 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 degrees and intraoperative values of 23.14 degrees on the Andrews table versus 32.94 degrees 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 degrees and intraoperative measurements of 20.06 degrees on the Andrews table versus 21.02 degrees 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.