The kinematic relationship between sitting and standing posture and pelvic inclination and its significance to cup positioning in total hip arthroplasty.

PURPOSE: The aim of this study is to describe the influence of sitting and standing posture on sagittal pelvic inclination in total hip replacement patients to assist with correct acetabular component positioning. METHODS: Lateral radiographs of the pelvis and lumbar spine in sitting and standing positions were extracted. Pelvic tilt was measured using the vertical inclination of a line from the anterior superior iliac spine (ASIS) to pubic tubercle. Sacral inclination, Cobb angle of the lumbar spine and hip flexion were recorded. RESULTS: Sixty patients were identified with a mean age of 63. Men were more likely to flex the lumbar spine in sitting (p = 0.004); 80° of hip flexion is required for seated posture. Stiff hips required compensatory pelvic flexion and lumbar flexion in sitting. There is a linear relationship between hip flexion and pelvic tilt, hip flexion and lumbar lordosis. CONCLUSIONS: Pelvic orientation is determined by lumbar and hip stiffness. This impacts on acetabular version.

Role of coflex as an adjunct to decompression for symptomatic lumbar spinal stenosis.

STUDY DESIGN: Prospective cohort study. PURPOSE: To assess whether additional implantation of Coflex following spinal decompression provided better clinical outcomes compared to decompression alone for symptomatic lumbar spinal stenosis (LSS) and to determine whether improvement in clinical outcomes correlated with changes in the radiological indices studied. OVERVIEW OF LITERATURE: Literature on benefits of additional Coflex implantation compared to decompression alone for symptomatic LSS is limited. METHODS: Patients with symptomatic LSS who met the study criteria were offered spinal decompression with Coflex implantation. Those patients who accepted Coflex implantation were placed in the Coflex group (n=22); while those opting for decompression alone, were placed in the comparison group (n=24). Clinical outcomes were assessed preoperatively, six-months, one-year and two-years postoperatively, using the Oswestry disability index, 100 mm visual analogue scale (VAS)-back pain and VAS-leg pain, and short form-36 (SF-36). Radiological indices (disc height, foraminal height and sagittal angle) were assessed preoperatively, six months, one year, and two years postoperatively. RESULTS: Both groups showed statistically significant (p<0.001) improvement in all the clinical outcome indicators at all points in time as compared to the preoperative status. However, improvement in the Coflex group was significantly greater (p<0.001) than the comparison group. Changes in the radiological indices did not correlate significantly with the improvement in clinical outcome indicators. CONCLUSIONS: Additional Coflex implantation after spinal decompression in symptomatic LSS offers better clinical outcomes than decompression alone in the short-term. Changes in radiological indices do not correlate with the improvements in clinical outcomes after surgery for symptomatic LSS.