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PURPOSE: The aim of our study was to assess the radio-clinical results, mid-term survivorship and dislocation rate of a new-generation dual-mobility cup. METHODS: The first 100 patients (104 primary total hip arthroplasties) who were implanted with a new-generation cementless dual-mobility cup (Sunfit TH, Serf, Décines) were included in our study, with a minimum follow-up of five years. RESULTS: Average follow-up was six years±0.44 (5-7). At last follow-up, the Harris and PMA scores were significantly improved, from 56 to 94 and 13 to 17 respectively (p

La myosite ossifiante circonscrite (MOC) est une affection benigne, rare, caracterisee par une ossification heterotopique localisee dans les tissus mous. Nous rapportons l’observation d’un adolescent de 15 ans se plaignant d’une douleur d’allure mixte a la hanche, aucun contexte traumatique n’a ete evoque a l’interrogatoire. Cette articulation avait un aspect inflammatoire et une tumefaction non mobilisable adherant au plan profond dont sa projection parietale comblait le pli de l’aine. Les radiographies de la hanche ont visualise un epaississement des parties molles de la hanche et des calcifications periarticulaires d’aspect flou. L’indication d’une biopsie exerese des calcifications a ete posee et realisee. Le diagnostic confirme par l’etude histologique d’un fragment biopsique. A six mois le patient etait tres satisfait du resultat fonctionnel de son membre. La reprise des activites sportives scolaires etait autorisee avec succes.

Introduction Increasing the femoral offset when performing total hip arthroplasty (THA) theoretically increases the stresses and risks of the stem not integrating itself into bone. But this concept has not been validated for cementless stems; this led us to conduct a retrospective study to determine: (1) the risk factors for the occurrence of symptomatic femoral radiological abnormalities, (2) the incidence of these abnormal radiological findings, (3) the revision rate for aseptic non-integration of a cementless lateralized stem. Hypothesis Young patients with significant femoral canal flare and a small cementless lateralized stem have a higher risk of abnormal osseointegration. Material and methods We analyzed retrospectively 172 consecutive lateralized stems (KHO, Corail™ product line) implanted during primary THA between 2006 and 2012 in 157 patients (mean age 68 years ± 12.6 (20–95), 89% men). Radiographs were used to evaluate osseointegration scores, offset restoration and the Noble index. Kaplan-Meier survival analysis was performed using “symptomatic femoral radiological abnormalities” and “revision for aseptic stem non-integration” as endpoints. Results The mean follow-up was 5.9 years ± 2.7 (range, 2–12.4 years). Being more than 70 years of age (HR = 0.7, 95% CI: [0.3–0.9], P = 0.004) and having a larger stem (HR = 0.6, 95% CI: [0.4–0.9], P = 0.03) were protective against symptomatic femoral radiological abnormalities, while increasing the postoperative femoral offset (HR = 1.1, 95% CI: [1.01–1.2], P = 0.02) was deleterious. The survival free of “symptomatic femoral radiological abnormalities” was 93% (95% CI: 89–97) at 5 years and 84% (95% CI: 75–95) at 8 years. The survival free of “revision for aseptic stem non-integration” was 98% (95% CI: 96.8–100) at 5 years and 97% (95% CI: 95.2–100) at 8 years. Discussion In this study, the risk factors for symptomatic radiological abnormalities were being less than 70 years of age, having a small lateralized stem and restoring a large femoral offset. Lateralized stems used in this study had a 10% rate of symptomatic radiological abnormalities and a 4% rate of revision for aseptic non-integration. Level of evidence IV, retrospective study.

Purpose Various methods exist for measuring limb length and lateralisation after total hip arthroplasty. Most of them utilise standard anteroposterior (AP) pelvic radiographs, but their results can be affected by patient position during imaging and thus the position of the lower limb on the coronal plane. The aim of this study is to evaluate how commonly used measuring methods of limb lengthening and femoral offset are affected by the position of the lower limb in the coronal plane. Methods A standing pelvic AP radiograph post implantation of a right total hip prosthesis was digitised. The right femur and its femoral stem were digitally segmented, such that they could be positioned orthogonal to the pelvis horizontal reference, with 10° of adduction, and with 10° of abduction, with respect to the centre of rotation. Various limb lengths and implant lateralisation were also digitised. We obtained nine x-rays differing one to three variables. Twice four independent surgeons performed three femoral length measurement methods and femoral offset measurement methods. Intra and inter-observer error as well as the effect of the femoral position on the measurements were studied. Results With respect to length measurements, the distance between the centre of rotation (C) and the tip of the lesser trochanter (LT) increased by 3 mm per cm of lateralisation. This measurement was not affected by the hip position in abduction or adduction. The distance between the tip of the lesser or greater trochanter (GT) and the horizontal passing through the centre of rotation was strongly affected by the hip position in abduction or adduction.With respect to offset, the distance between the centre of rotation and the greater trochanter (C-GT) was the most consistent and was not affected by variations in lengths or femoral axis. At the level of the lesser trochanter, the distance of the femoral anatomical axis and to Perkin's line was heavily influenced by the femoral position. Conclusion The C-LT distance was consistent in measuring limb length and the C-GT distance was reliable in determining femoral offset regardless of the relative position of the femur.

PurposeTo compare the individual influence of different types of socket designs on the hip's range of motion in transfemoral amputees.Patients and methodsWe studied the kinematic parameters of the hip joint for patients with transfemoral amputation under four experimental conditions: without a socket, with a quadrilateral socket, an ischial containment socket, an ischial-ramal containment socket. An opto-electronic system was used to record the movements in the frontal and sagittal planes for a 3D movement analysis.ResultsThe hip's range of motion is always significantly restricted with the sockets, regardless of their type, compared to the situation without a socket (P

A global coordinate system (GCS) method is proposed to estimate hip and lumbosacral joint centers (HJC and LSJC) from at least three distances between joint center of interest and target anatomic landmarks (ALs). The distances from HJC and LSJC to relevant pelvis and femur ALs were analyzed with respect to usual pelvis and femur scaling dimensions. Forty six pelves and related pairs of femurs from a same sample of adult specimens were examined. The corresponding regression equations were obtained. These equations can be used to estimate HJC and LSJC in conditions where a very limited number of ALs are available: for example, during seated posture analysis as performed in the automotive industry. Compared to currently existing HJC and LSJC methods from ALs, the proposed method showed better results with an average error less than 11 mm.

38ième congrès de la Société de Biomécanique francophone, MARSEILLE, FRANCE, 06-/09/2013 - 09/09/2013; Measuring hip joint centre (HJC) for seated posture in an automotive environment is a difficult task, because only a very limited number of anatomical landmarks (ALs) can be measured. There exist two classes of methods for estimating HJC location (see Bull et al. 2012 for a short review): regression method and functional method. However, they are not well suited to be directly applied to automotive seated posture. Recently, Bull et al. (2012) showed that the uncertainty in HJC by these two methods applied to automotive seated posture could be up to 4 cm due to errors in AL manual palpation and soft tissue artefacts. Interestingly, Bush and Gutowski (2003) proposed a method of locating HJCs for seated postures only using the right and left anterior superior iliac spines ([R/L]IAS) and the right or left femoral lateral epicondyles of the knee by assuming that the distances between HJC and these three ALs remained constant when changing posture. These distances needed to be firstly determined in an initial reference posture by Seidel's method. However, one strong limitation of Seidel's method is that the palpation of the pubic joint landmark (IPJ) is required, which usually causes volunteers to feel uncomfortable. Similar to the method by Bush and Gutowski, the aim of this study was to explore other ALs than IPJ for determining HJC. More specifically, the ilium ischial tuberosity (IIT) could be an alternative candidate as it can be indirectly estimated with the help of a pressure map by assuming that the highest pressure point corresponds to IIT when seated on a flat hard surface. In this study, data collected by Universite ?Libre de Bruxelles (ULB) from 48 adult cadaveric specimens were used for establishing regression equations. The proposed equations were compared with other existing bony landmark-based methods

L’ostéome ostéoïde est une tumeur osseuse bénigne qui affecte les adultes jeunes et se localise préférentiellement au niveau des os longs. La localisation intra-articulaire est rare et atteint le plus souvent la hanche. La symptomatologie clinique est alors atypique et peut faire errer le diagnostic constituant un défi diagnostique pour les cliniciens. Nous rapportons deux observations d’ostéome ostéoïde intra-articulaires de la hanche chez deux hommes âgés 24 et 45 ans, révélés par des douleurs de la hanche gauche de type inflammatoire évoluant depuis un an et un an et demi respectivement. Chez les deux patients, le tableau atypique de l’ostéome ostéoïde a été à l’origine d’un retard diagnostic. La tomodensitométrie est dans cette indication l’examen le plus spécifique qui a permis d’évoquer le diagnostic d’ostéome ostéoïde. Une fois le diagnostic est posé, l’exérèse chirurgicale à ciel ouvert a permis la guérison avec disparition totale des douleurs. L’examen histologique a confirmé le diagnostic final d’ostéome ostéoïde intra-articulaire dans les deux cas.Key words: Ostéome ostéoïde, hanche, tomodensitométrie, chirurgie, Tunisie

Summary Background objective Femoral offset is supposed to influence the results of hip replacement but little is known about the accurate method of measure and the true effect of offset modifications. Material and methods This article is a collection of independent anatomic, radiological and clinical works, which purpose is to assess knowledge of the implications of femoral offset for preoperative templating and total hip arthroplasty. Results There is a strong correlation between femoral offset, abductors lever arm and hip abductor strength. Hip lateralization is independent of the femoral endomedullary characteristics. The abductors lever arm is highly correlated to the gluteus medius activation angle. There were correlations between femoral offset and endomedullary shape. The hip center was high and medial for stovepipe metaphysis while it was lower and lateralized for champagne – flute upper femur. A study was performed to compare the femoral offset measured by X-ray and CT-scan in 50 patients, demonstrated that plain radiography underestimates offset measurement. The 2D templating cannot appreciate the rotation of the lower limb. Taking into account the horizontal plane is essential to obtain proper 3D planning of the femoral offset. A randomized study was designed to compare femoral offset measurements after hip resurfacing and total hip arthroplasty. This study underlined hip resurfacing reduced the femoral offset, while hip replacement increased offset. However, the reduction of femoral offset after hip resurfacing does not affect the function. A pilot study was designed to assess the results of 120 hip arthroplasties with a modular femoral neck. This study showed that the use of a modular collar ensures an easier restoration of the femoral offset. A cohort of high offset stems (Lubinus 117°) was retrospectively assessed. The survival rate was slightly lower that the standard design reported in the Swedish register. Finally, the measurement of offset and leg length was assessed with the help of computer assistance. The software changed the initial schedule (obtained by templating) in 29%. Conclusion Therefore, femoral offset restoration is essential to improve function and longevity of hip arthroplasty. CT-scan is more accurate than plain radiography to assess femoral offset. Hip resurfacing decreases offset without effect on function. Modular neck and computer assistance may improve intraoperative calculation and reproduction of femoral offset. Increasing offset with a standard cemented design may decrease long-term fixation. Level IV: Retrospective or historical series.

The aim of this study is to elaborate a mechanical model of the healthy hip joint. The main objective is to use it as a reference model in order to analyse pathological hip joint mechanical behaviours and evaluate prescribed treatment by comparison of pre vs. post simulated behaviours. Therefore, a generic finite element model of the hip joint is developed. Experimental acquisitions of kinematical and kinetic data are implemented in a musculo-skeletal model to calculate muscular forces acting at the hip joint. Our approach consists in coupling an inverse dynamic method with static optimisation. From the evaluation of each individual hip muscle force, the contact reaction force is computed. The contact reaction force is then implemented in the finite element model in order to perform simulations for several instants of the stance phase of gait and stair climbing. Contact pressure distributions during the stance phase of gait are compared to those available in the literature, measured in vivo by mean of instrumented prosthesis or cadaveric experiments simulating gait cycles. A clinical application concerns the evaluation of the effect of foot orthoses on the mechanical behaviour of an osteoarthritic hip joint. The loading conditions at the hip joint, when the patient is walking or climbing a step successively with and without foot orthoses, is determined in each experimental conditions using the approach previously described., L'objectif de ce travail est d'élaborer un modèle mécanique de la hanche saine susceptible d'être utilisé comme référence pour pouvoir ensuite analyser le comportement de hanches pathologiques en évaluant l'effet des traitements préconisés par comparaison des différents comportements simulés. Dans ce contexte, un modèle éléments finis générique de l'articulation de la hanche est développé. Il est également nécessaire de déterminer l'état de chargement de l'articulation de la hanche pour notre simulation. L'analyse du mouvement permet le calcul des données cinématiques et dynamiques à partir des mesures expérimentales. A partir de ces données, un modèle musculo-squelettique associant une méthode de dynamique inverse et d'optimisation statique, permet de déterminer les efforts musculaires mis en jeu par les muscles croisant l'articulation de la hanche. L'évaluation des forces développées par les muscles de la hanche permet de calculer la réaction de contact articulaire exercée par le fémur sur le bassin. C'est cette réaction que nous implémentons dans le modèle éléments finis. Ainsi, les simulations du comportement de la hanche saine sont réalisées pour la phase d'appui de la marche et la phase d'appui de la montée d'escaliers. Nous traitons ensuite d'une application clinique visant à évaluer l'influence du port d'une orthèse podale sur le comportement mécanique d'une hanche arthrosique. La démarche suivie est la même que celle mise en place pour l'étude du comportement de la hanche saine. L'état de chargement de la hanche arthrosique est déterminé chez le patient pendant la marche et la montée d'escaliers évoluant successivement avec puis sans orthèses.

Restoring the native hip anatomy increases hip prosthesis survival, whereas increased femoral lateralisation creates high torque stresses that may alter prosthesis fixation. After finding lucent lines around cementless lateralised stems (CorailTM, DePuy Synthes, St Priest, France) in several patients, we evaluated the effects of lateralisation in a large case-series. The objective of our study was to compare lateralised vs standard stems of identical design in terms of radiological osteo-integration and survival. HYPOTHESIS: Lateralised stems, despite being used only when indicated by the anatomical parameters, carry a higher risk of impaired osteo-integration. MATERIALS AND METHODS: A retrospective study was conducted in 807 primary total hip arthroplasties (THAs) performed between 2006 and 2010 in 798 patients with a mean age of 65 ± 14.2 years. Lateralised stems were used in 280 cases (Corail High Offset KHO, n = 169; and Corail coxa vara KLA, n = 111 cases) and standard stems in 527 cases (Corail KA). Mean follow-up was 2.3 years (range, 1-7 years). The clinical evaluation included determination of the Postel-Merle d'Aubigné (PMA) score. Bone fixation and stability of the implants were assessed by determining the Engh and Massin score and the ARA score on the radiographs at last follow-up. Femoral, acetabular and global offset values were determined before and after THA. Nobles's Canal Flare Index was computed. Survival was estimated using the Kaplan-Meier method with surgical revision for aseptic loosening as the end-point. RESULTS: The PMA score improved from 12 (10-15) pre-operatively to 17.7 (14-18) (P < 0.05). After THA, in the lateralised stem group, femoral offset was restored in 217 (77%) hips and the mean change vs the pre-operative offset value was -2 mm; in the standard stem group, femoral offset was restored in 440 (83.5%) hips and the mean change was +1 mm. The Engh and Massin score values were similar in the standard stem and lateralised stem groups (24.4 ± 2.2 and 22.6 ± 2.4, respectively, NS). Revision for aseptic loosening was required in 5 patients with lateralised stems (3 KHO and 2 KLA) versus none of the patients with standard stems. There were no cases of excessive femoral offset and the mean change in offset was -2.3mm (-5.3 to -1.1). Noble's index was increased (4.27 ± 0.5 for the loosened lateralised stems, 3.65 ± 0.8 for the well-fixed lateralised stems and 3.82 ± 0.6 for the standard stems), with no significant difference across groups. Overall survival after 3.5 years of follow-up was 94.6% (95% confidence interval, 88.4-100%) with lateralised stems and 100% with standard stems (P < 0.05). DISCUSSION: The risk of aseptic loosening was significantly higher with the lateralised stem (5/280, 1.8%) than with the standard stem (n = 0). Our findings indicate a need for careful preparation to obtain primary fixation of lateralised stems. LEVEL OF EVIDENCE: III, retrospective case-control study.