Adrien Brusson

Hip–spine relations and sagittal balance clinical consequences

IntroductionThe role of the pelvic area in sagittal balance is evident for spinal surgeons, but the influence of the coxofemoral joint is underestimated and inadequately explained by conventional imagery. Comprehensive analysis of the pelvic and subpelvic sectors as part of the sagittal, frontal and cross-sectional balance of the trunk sheds new light on some spinal diseases and their relation to the pelvis.MethodsThis analysis, based on innovative radiologic methods as the EOS® technology but also on a new look at conventional imaging makes it possible to better analyze standing lateral images and seated images.ResultsDisturbances can come from atypical morphotypes or from unusual postures as in aging spine. The measurement of available extension and the concept of available flexion provide new information regarding individual’s adaptation to the imbalance induced by disorders of the spine or lower limbs.ConclusionA comprehensive assessment of each patient and in particular of the complex comprising the spine and the pelvis, is essential for understanding each individual’s adaptation to the imbalance induced by disorders of the spine or lower limbs.

Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: Measurements reproductibility with EOS imaging system versus conventional radiographies

INTRODUCTION The literature has recently underlined the interest of pelvic and acetabular component orientation measurements in the standing and sitting position. Radiographic follow-up of total hip arthroplasty (THA) is based on standard AP and lateral X-rays. The use of EOS™ 2D imaging system reduces patients radiation exposure compared to conventional X-rays. However, using this system, the validity and reproducibility of angular measurements, have not been studied yet for the measurement of pelvic and acetabular parameters in patients with THA. HYPOTHESIS The EOS™ 2D imaging system offers similar advantages to conventional X-rays in the measurement of pelvic and acetabular orientation parameters which are commonly used. PATIENTS AND METHOD Five angular parameters characterizing pelvic tilt and acetabular cup orientation were determined using the same digital measurement Imagika™ software based on two series of standard X-rays and EOS™ 2D images acquired in both standing and sitting positions. Radiographs from 50 patients with unilateral THA were measured three times by two observers. Intra- and interobserver reproducibility using each method was independently studied then paired comparison was performed. RESULTS The ICC and Spearman rank correlation coefficient demonstrated an excellent EOS/conventional X-ray correlation. According to the parameters, the mean difference between these two imaging modalities ranged from 0.30° to 3.43° (P<0.05). The intra- and interobserver variability ranged from ± 2.97° to ± 6.46° using the EOS™ imaging system and from ± 4.26° to ± 10.22° using conventional X-rays (P<0.05). DISCUSSION The EOS™ 2D imaging system may replace conventional X-rays in the assessment and monitoring of pelvic and acetabular cup orientation in THA. LEVEL OF EVIDENCE Level III. Prospective diagnostic study.

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

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.

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.

Risk of Impingement and Third-body Abrasion With 28-mm Metal-on-metal Bearings

BackgroundConcerns have been raised about the sequelae of metal-on-metal (MoM) bearings in total hip arthroplasty (THA). However, retrieval studies, which offer the best insight into the clinically relevant mechanisms of MoM wear, have followed predictable trends to date such as indicting cobalt-chromium (CoCr) metallurgy, cup design, high conformity between the head and cup, “steep cups,” “microseparation,” and “edge wear.”Questions/purposesWe wished to evaluate a set of retrieved 28-mm MoM THA for signs of (1) cup-to-stem impingement; (2) normal wear pattern and concomitant stripe damage on femoral heads that would signify adverse wear mechanics; and (3) well-defined evidence of third-body scratches on bearings that would indicate large abrasive particles had circulated the joint space.MethodsTen 28-mm MOM retrievals were selected on the basis that femoral stems were included. Revision surgeries at 3 to 8 years were for pain, osteolysis, and cup loosening. CoCr stems and the MoM bearings were produced by one vendor and Ti6Al4V stems by a second vendor. All but two cases had been fixed with bone cement. We looked for patterns of normal wear and impingement signs on femoral necks and cup rims. We looked for adverse wear defined as stripe damage that was visually apparent on each bearing. Wear patterns were examined microscopically to determine the nature of abrasions and signs of metal transfer. Graphical models recreated femoral neck and cup designs to precisely correlate impingement sites on femoral necks to cup positions and head stripe patterns.ResultsThe evidence revealed that all CoCr cup liners had impinged on either anterior or posterior facets of femoral necks. Liner impingement at the most proximal neck notch occurred with the head well located and impingement at the distal notch occurred with the head rotated 5 mm out of the cup. The hip gained 20° motion by such a subluxation maneuver with this THA design. All heads had stripe wear, the basal and polar stripes coinciding with cup impingement sites. Analysis of stripe damage revealed 40 to 100-μm wide scratches created by large particles ploughing across bearing surfaces. The association of stripe wear with evidence of neck notching implicated impingement as the root cause, the outcome being the aggressive third-body wear.ConclusionsWe found consistent evidence of impingement, abnormal stripe damage, and evidence of third-body abrasive wear in a small sample of one type of 28-mm MoM design. Impingement models demonstrated that 28-mm heads could lever 20° out of the liners. Although other studies continue to show good success with 28-mm MoM bearings, their use has been discontinued at La Pitie Hospital.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

All Ceramic Tripolar THA to Prevent Dislocations in Risky Patients

Dislocation remains one of the most common complications after total hip arthroplasty (THA), especially for ceramic-on-ceramic prostheses. Suboptimal implant positioning, mus‐ cular insufficiency, significant lower limb discrepancies, and neurological problems are standard causes for THA dislocations or subluxations [1-3]. Instability may also be linked to 2 specific mechanisms, lever-out (with impingement) and shear-out (without impingement).