Lumbopelvic lordosis and pelvic balance on repeated standing lateral radiographs of adult volunteers and untreated patients with constant low back pain

Study Design. Twenty volunteers and 20 patients with no prior spine surgery had two standing lateral radiographs taken, on the average, 66 months apar t and 2 weeks apart, respectively. Objectives, To first determine the reliability of the measurement technique s used, and then the longitudinal variation between radiographs for the sag ittal spinopelvic alignments measured in two stable populations, the one ma nifesting no back symptoms (volunteers) and the other showing no changes in symptoms (patients). Pelvic morphology also was assessed quantitatively, a nd significant correlations for the measurements were studied. Summary of Background Data. There are no published studies on longitudinal variation for measurements of sagittal spinal alignments in asymptomatic co ntrol subjects or untreated patients with stable back problems. It may be h elpful to know not only how much variation in alignments can be expected be tween radiographs of the same individual, but also which measurements and m easurement techniques offer the greatest clinical reliability and applicati on, Methods. Each patient in this study reported mechanical type low back pain that was constant in location and character as well as clinically consisten t with symptomatic degenerative lumbar disc disease. Each patient and volun teer had 36-inch-long lateral radiographs taken of the entire thoracic and lumbar spine, which included the pelvis. After intervening periods of 1 to 4 weeks (patients) and 5 to 6 years (volunteers), a second radiograph was t aken for comparison. Two observers made 24 different measurements on the ra diographs including determinations for lumbopelvic lordosis, pelvic balance , and pelvic morphology using the pelvic radius technique. Reliabilities, l ongitudinal variations, and correlations for the measurements were compared . Results. The most reliable measurements were for pelvic morphology, pelvic balance, and regional lumbopelvic lordosis by the pelvic radius technique. Pelvic morphology was the most constant measurement between individual radi ographs. Pelvic morphology and total lumbosacral lordosis were dependent me asurements that were complementary in determining total lumbopelvic lordosi s. Lumbopelvic lordosis and pelvic balance also had strong correlation, whe reas lumbosacral lordosis and pelvic balance were independent measurements. Conclusions. The pelvic radius technique is recommended for evaluating lord osis to the pelvis because this approach provided not only good measurement reliability on standing radiographs for lumbopelvic lordosis, but also det ermination of pelvic balance over the hips and the option to assess pelvic morphology quantitatively. Lumbopelvic lordosis and pelvic balance were str ongly correlative. This finding along with higher reliability and lower lon gitudinal variation on repeated radiographs, indicated greater clinical app lication for these specific measurements.