Changes In Pelvic Orientation After Total Hip Arthroplasty : A Prospective Study With EOS™.

Changes in pelvic orientation after THA could alter the relationship between the femoral stem and the acetabular component and may be responsible of dislocation and implant degeneration. EOS™ technology allows three-dimensional analysis of the pelvis in functional position with low irradiation. The purpose of the study was to evaluate changes in pelvic orientation after THA in standing position with EOS™. In a prospective study, EOS™ was performed in standing position preoperatively and 3 months after computer assisted THA for primary hip osteoarthritis. Differences between pre- and postoperative pelvic parameters values were analyzed. 40 patients were included. Changes greater than 5° was noted in 12,5% of cases for pelvic incidence, 35% of cases for sacral slope and in 22,5% of cases for pelvic version. In conclusion, pelvic parameters could be modified after THA.

Three-dimensional morphologic study of the child's hip: which parameters are reproducible?

BACKGROUND: Biplanar x-ray images obtained with patients in a standing weightbearing position allow reconstruction of three-dimensional (3-D) bone geometries, with lower radiation exposure than CT scans and better bone definition than MRI. QUESTIONS/PURPOSES: We determined the reproducibility of 3-D parameter values of the hips and pelves of healthy children, using biplanar x-ray images. METHODS: We built 3-D models of the hips of 33 children without musculoskeletal problems: 10 subjects younger than 9 years and 23 who were 9 years or older. Three anatomic landmarks and nine hip and pelvic parameters were computed for each reconstruction. To determine the reliability of these landmarks and parameters, each bone was reconstructed four times by two independent observers, leading to a total of 264 reconstructions, and parameters were studied for the two age groups and compared between dancers and nondancers. RESULTS: Taking into account all reconstructions, the interobserver reproducibility ranged from 2 to 4 mm for landmark positions or distance parameters, and 2° to 6° for angular parameters. The most reproducible point was the center of the femoral head (range, 0.2-17 mm). The distance between this center and its projection on the plane fitting the edge of the acetabulum, and the pelvic tilt were the most reproducible parameters. CONCLUSIONS: Reproducible 3-D reconstructions of hips and pelves of children were possible using biplanar x-ray images, regardless of the children's ages. Although we report preliminary values for 3-D parameters in healthy children's hips, further work is needed to obtain direct validation of our parameters using CT reconstructions of cadaveric specimens to avoid high doses of radiation.

In vivo study of the kinematics in axial rotation of the lumbar spine after total intervertebral disc replacement: long-term results: a 10-14 years follow up evaluation.

INTRODUCTION: We did not find any in vivo study of spinal segment kinematics after disc replacement, especially over the long term. In vitro studies did show that it restores almost normal kinematics except for axial rotation. The goal of this study is to develop a new technique in order to analyse axial rotation of a spinal segment, in vivo, after total disc replacement. MATERIALS AND METHODS: A comparative retrospective study of motion in axial rotation at L4L5 level was carried out on 17 patients with artificial discs versus six healthy volunteers. Five patients carried one prostheses at L4L5 level and 12 carried two prosthesis at L4L5 and L5S1 levels. The follow up ranged from 10.8 to 14.3 years (average 12.4+/-1, median 12.6). Dynamic radiographs in axial rotation were made using a special protocol. A new technique associating a stereographic method and image processing software was developed in order to evaluate the range of motion in axial rotation as well as the mechanical coupling. RESULTS: The standard deviation of angular measurements was 1.8 degrees . Eleven (65%) patients had a normal mobility in torsion, identical to those of the volunteers and of the literature, whereas six (35%) had an abnormal increased mobility. If only one disc was replaced, mobility in torsion was identical to that of the volunteers, in the case of two replaced discs, 50% (6/12) of the patients had an abnormal increased mobility. In the sub-group of normal mobility, the coupling was identical to that of the volunteers. In the sub-group of increased mobility, the coupling was different with a strong flexion (10 degrees ), increased by about 7 degrees (P<0.001). CONCLUSION: The implementation of only one discal prosthesis SB Charité seems to restore kinematics close to that of the healthy volunteers and comparable to the literature. The implementation of two adjacent prostheses does not restore normal kinematics in 50% of the cases. It is probable that the existence of active stabilizing elements explains the difference with the in vitro studies carried out beforehand.

Clinical and radiological outcomes with the Charité artificial disc: a 10-year minimum follow-up.

This is the first report of clinical and radiologic outcomes for the CHARITE artificial disc with a minimum follow-up of 10 years. A total of 107 patients indicated for total lumbar disc replacement were implanted with the CHARITE prosthesis. Of these 107, 100 were followed for a minimum of 10 years (range 10-13.4 years). A total of 147 prostheses were implanted with 54 one-level and 45 two-level procedures and 1 three-level procedure. The prostheses were placed through a standard anterior retroperitoneal approach. Clinically, 62% had an excellent outcome, 28% had a good outcome, and 10% had a poor outcome. Of the 95 eligible to return to work, 88 (91.5%) either returned to the same job as prior to surgery or a different job. These included 63.2% (12) of those working in heavy labor employment returning to the same job. Mean flexion/extension motion was 10.3 degrees for all levels (12.0 degrees at L3-L4, 9.6 degrees at L4-L5, 9.2 degrees at L5-S1). Mean lateral motion was 5.4 degrees . In the sagittal plane, 9 (6.1%) were anterior of geometric center, 50 (34.0%) were centered, and 88 (59.9%) were posterior of center. In the frontal plane, 110 (75%) were centered, and 37 (25%) were noted to be lateral to center. Slight subsidence was observed in two patients, but they did not require further surgery. No subluxation of the prostheses and no cases of spontaneous arthrodesis were identified. There was one case of disc height loss of 1 mm. Five patients required a secondary posterior arthrodesis. A good or excellent clinical outcome rate of 90% and a return to work rate of 91.5% compare favorably with results described in the literature for fusion for the treatment of lumbar degenerative disc disease. With a minimum follow-up of 10 years, the CHARITE artificial disc demonstrated excellent flexion/extension and lateral range of motion with no significant complications.