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Objective: The study hypotheses were that: (i) there would be a difference in sagittal plane alignment between patients with symptomatic osteoarthritis of the hip and those with lumbar degenerative disk disease; and (ii) that sagittal plane lumbar alignment would change following total hip arthroplasty (THA)., Methods: In this prospective study, a series of patients without back pain or lumbar complaints who were scheduled to undergo THA underwent lateral lumbar radiography prior to and nine months after elective THA. Radiographic measurements of lumbar alignment included sacral slope, lumbar lordosis, and L1 axis S1 distance (L1 ASD). All measurements were performed on upright, standing, lateral radiographs. A control group of patients underwent serial radiography over the same period for evaluation of lumbar degenerative disease. The independent sample t-test was used to compare the mean sacral slope, lumbar lordosis, and L1 ASD in the THA and control groups., Results: There were 12 patients in the THA group and 34 in the control group. Mean follow-up was 9 months. Average age in the control group was 63 years and in the THA group 64.2 years. The sacral slope was greater in the THA group (mean, 23°) than in the lumbar patients (control group) and this difference was statistically significant (mean, 11°, P = 0.001). There were no statistically significant differences between THA and control patients in lumbar lordosis or L1 ASD. Change before and after THA was measured. There were no statistically significant differences in assessed radiographic variables preoperatively versus postoperatively., Conclusion: There is no significant change in spinal alignment after unilateral THA. At baseline, patients with symptomatic spine complaints have less sacral slope than their hip arthroplasty counterparts., (© 2013 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.)

Objective: The hypothesis of this study is that pelvic obliquity (PO) is associated with specific patterns of degenerative scoliosis., Methods: This study was a retrospective case series of consecutive patients undergoing fusion for lumbar conditions (degenerative scoliosis or spondylolisthesis). The discrepancy in the iliac crest height, coronal L1-S1 endplate angles, distance from L1 coronal bisector to the sacral center, number of degenerative scoliosis curves, and individual curve angulations were measured., Results: Limb length discrepancy was present in 87% of patients with a degenerative scoliosis. There were 116 patients with a single curve > 5° and PO > 2 cm. Of the patients with a single curve, the apex of scoliosis was opposite the high iliac crest side in 79% patients. There were 338 patients with a double curve. The apex of scoliosis was opposite the high iliac crest side in 48% of patients., Conclusion: There were distinct patterns of limb length discrepancy corresponding to degenerative scoliotic curve morphology. In patients with single degenerative scoliotic curves, PO most commonly appeared to counteract the scoliotic curve and result in an overall decrease in trunk shift. This occurred because the high iliac crest was observed most commonly on the convex side of the scoliotic curve. This effect was not observed in double lumbar degenerative scoliotic curves., (© 2013 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.)