Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology

This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.More total hip arthroplasty (THA) is performed worldwide and especially in younger and more active patients compared to earlier decades. One of the focuses of THA research in the future will be on optimizing the radiological follow-up of these patients using 2D and 3D measurements of implants position while reducing the radiation dose delivered. Low-dose EOS(®) imaging is an innovative slot-scanning radiograph system providing valuable information in patient functional positions (standing, sitting and even squatting positions). EOS has been proven accurate and reliable without significant inconvenience caused by the metallic artifacts of implants. The ability to obtain precise data on implant orientation according to the patient posture opens new perspectives for a comprehensive analysis of the pelvic frontal and sagittal balance and its potential impact on implants function and failures. We report our 8 years experience on our first 300 THA patients using this technology routinely for pre and post op evaluation. Our results will be compared and confronted with the actual literature about this innovative technology. We shall especially emphasize our experience about patients with abnormal posture and the evolution of the subject over time, because the phenomenon of an aging spine is frequently associated with the process of aging hips

Offset and anteversion reconstruction after cemented and uncemented total hip arthroplasty: an evaluation with the low-dose EOS system comparing two- and three-dimensional imaging

Purpose Accurate evaluation of femoral offset is difficult with conventional anteroposterior (AP) X-rays. The EOS imaging system is a system that makes the acquisition of simultaneous and orthogonal AP and lateral images of the patient in the standing position possible. These twodimensional (2D) images are equivalent to standard plane Xrays. Three-dimensional (3D) reconstructions are obtained from these paired images according to a validated protocol. This prospective study explores the value of the EOS imaging system for comparing measurements of femoral offset from these 2D images and the 3D reconstructions. Methods We included 110 patients with unilateral total hip arthroplasty (THA). The 2D offset was measured on the AP view with the same protocol as for standard X-rays. The 3D offset was calculated from the reconstructions based on the orthogonal AP and lateral views. Reproducibility and repeatability studies were conducted for each measurement. We compared the 2D and 3D offset for both hips (with and without THA). Results For the global series (110 hips with and 110 without THA), 2D offset was 40 mm (SD 7.3; 7–57 mm). The standard deviation was 6.5 mm for repeatability and 7.5 mm for reproducibility. Three-dimensional offset was 43mm(SD 6.6; 22–62 mm), with a standard deviation of 4.6 for repeatability and 5.5 for reproducibility. Two-dimensional offset for the hips without THA was 40 mm (SD 7.0; 26–56 mm), and 3D offset 43 mm (SD 6.6; 28–62 mm). For THA side, 2D offset was 41mm(SD 8.2; 7–57mm) and 3D offset 45mm(SD 4.8; 22–61 mm). Comparison of the two protocols shows a significant difference between the 2D and 3D measurements, with the 3D offset having higher values. Comparison of the side with and without surgery for each case showed a 5-mm deficit for the offset in 35 % of the patients according to the 2D measurement but in only 26 % according to the 3D calculation. Conclusions This study points out the limitations of 2D measurements of femoral offset on standard plane Xrays.The reliability of the EOS 3D models has been previously demonstrated with CT scan reconstructions as a reference. The EOS imaging system could be an option for obtaining accurate and reliable offset measurements while significantly limiting the patient’s exposure to radiation

Measuring extension of the lumbar-pelvic-femoral complex with the EOS® system.

Introduction Sagittal balance of the coxofemoral joint in standing position and its extension capacity determine hip/spine adaptation, especially in relation to pelvic retroversion, which may be age-associated or follow either spinal arthrodesis or vertebral osteotomies. The concept of extension reserve is essential for assessing posterior hip impingement. The global visualization of the lumbar–pelvic–femoral complex obtained by EOS® imaging enables this sagittal analysis of both the subpelvic region and lumbar spine by combining the reference standing position and the possibility of dynamic tests. Materials and methods We studied 46 patients and their 92 hips. The EOS® radiography was performed in neutral standing position and with one foot on a step, alternately the right and left feet. Pelvic incidence, sacral slope, pelvic version, and femoral version were measured twice by two operators. The global extension reserve (GER) was defined by the sum of the intrinsic extension reserve (allowed by the hips, IER) and the extrinsic extension reserve (allowed by the spine, EER). The IER for each hip corresponds to the difference in the sacrofemoral angle (SFA) for each of the two positions. The EER was measured by the difference in the sacral slope. A descriptive study was performed, together with studies of inter- and intra-observer reproducibility, right/left symmetry, and an analysis according to age, sex, and BMI. Results The mean femoral version in the reference position was 11.7° (SD 14.3°). The reproducibility of the SFA measurement was statistically verified. The IER (mean 8.8°), EER (mean −0.7°), and GER (mean 8.2°) all differed significantly between the two sides for each patient and were not associated with age, sex, or BMI. Discussion The femoral axis is not perpendicular to the ground in neutral position, contrary to the conventional view of this position. The measurements proposed for dynamic sagittal analysis of the hip are reproducible and make it possible to identify the IER within the GER of the spinal–pelvic–femoral complex. Conclusion The assessment of the lumbar–pelvic–femoral complex by EOS imaging makes it possible to define the intrinsic and extrinsec extension reserves to describe the reciprocal adaptive capacities of the hips and spine. Level of evidence IV

Do Patients’ Perceptions of Leg Length Correlate With Standing 2- and 3-Dimensional Radiographic Imaging?

BACKGROUND: This study compared 2- and 3-dimensional (2D and 3D) radiographic measurements of anatomical and functional leg length and knee coronal and sagittal alignments and correlated these measurements with patients' leg-length perceptions. METHODS: Patients without symptomatic spinal pathology, previous surgery of the spine, and lower extremities (140 lower extremities) were evaluated on EOS images obtained in standing position. Numerous measurements of each limb were compared to the contralateral limb. All 2D/3D measures were evaluated and compared for repeatability and reproducibility. RESULTS: Mean 2D functional and anatomical lengths were 78.7 cm (64.7-88.4, confidence interval [CI] 95%: 77.4-80) and 78.3 cm (64.9-87.9, CI 95%: 77-79.6), respectively. Mean 3D functional and anatomical lengths were 78.9 cm (65.1-88.7, CI 95%: 77.6-80.2) and 78.9 cm (65.6-88.3, CI 95%: 77.8-80.5), respectively (P 10° of flexum/recurvatum were 2.1× more likely to perceive unequal length (P < .1). Patients with irreducible varus/valgus knee deformity were 4× more likely to perceive unequal length (P < .04). CONCLUSION: EOS imaging allows more accurate assessment of anatomical and functional lengths. Patients' perceptions of lower extremity length may correlate more closely with coronal and sagittal alignments of the knee than with femoral or tibial length. This study highlights the importance of physical examination of all the joints and 3D measurements in functional standing position.This study was unfunded

Clinical outcomes, radiologic kinematics, and effects on sagittal balance of the 6 df LP-ESP lumbar disc prosthesis

Background context: Surgical treatment of degenerative disc disease remains a controversial subject. Lumbar fusion has been associated with a potential risk of segmental junctional disease and sagittal balance misalignment. Motion preservation devices have been developed as an alternative to fusion. The LP-ESP disc is a one-piece deformable device achieving 6 df, including shock absorption and elastic return. This is the first clinical report on its use. Purpose: To assess clinical outcomes and radiologic kinematics in the first 2 years after implantation. Study design: Prospective cohort of patients with LP-ESP total disc replacement (TDR) at the lumbar spine. Patient sample: Forty-six consecutive patients. Outcome measures Clinical outcomes were the visual analog scale (VAS) for pain, the Oswestry disability index (ODI), and the GHQ28 (General Health Questionnaire) psychological score. Radiologic data were the range of motion (ROM), sagittal balance parameters, and mean center of rotation (MCR). Methods: Patients had single-level TDR at L4–L5 or L5–S1. Outcomes were prospectively recorded for 2 years (before and at 3, 6, 12, and 24 months after surgery). The SpineView software was used for computed analysis of the radiographic data. Paired t tests were used for statistical comparisons. Results: No intraoperative complication occurred. All clinical scores improved significantly at 24 months: the back pain VAS scores by a mean of 4.1 points and the ODI by 33 points. The average ROM of the instrumented level was 5.4°±4.8° at 2 years and more than 2° for 76% of prostheses. The MCR was in a physiological area in 73% of cases. The sagittal balance (pelvic tilt, sacral slope, and segmental lordosis) did not change significantly at any point of the follow-up. Conclusions: Results from the 2-year follow-up indicate that LP-ESP prosthesis recreates lumbar spine function similar to that of the healthy disc in terms of ROM, quality of movement, effect on sagittal balance, and absence of modification in the kinematics of the upper adjacent level