Computer-assisted two-dimensional preoperative planning for total hip arthroplasty: clinical evaluation.

The purpose of this study is to clinically validate a new two-dimensional preoperative planning software for cementless total hip arthroplasty (THA). Manual and two-dimensional computer-assisted planning were compared by an independent observer for each of the 30 patients with osteoarthritis who underwent THA. This study showed that there were no statistical differences between the results of both preoperative plans in terms of stem size and neck length (<1 size) and hip rotation center position (<5 mm). Two-dimensional computer-assisted preoperative planning provided successful results comparable to those using the manual procedure, thereby allowing the surgeon to simulate various stem designs easily.

BIOMECHANICAL EVALUATION OF ORTHOPAEDIC CEMENT COMBINED WITH ANTIBIOTIC AND METHYLENE BLUE

Objective: Acrylic cement has been used for years on orthopaedic surgeries, especially on knee arthroplasties, deserving special attention when added to antibiotics (for treatment of deep bone infections) or stains (to facilitate its removal). The present study was conducted in order to evaluate potential mechanical differences between the orthopaedic cement itself and when this is added to antibiotic and/or stains. Methods: Surgical bone cement Simplex@P Stryker, vancomycin and methylene blue were used, and the mixtures were submitted to physical and mechanical tests according the ABNT NBR ISO 5833 rule. The parameters studied here were: time for mass formation, intrusion capability, resistance to compression, resistance to flexion and maximum temperature reached by the mixtures. Results: The evaluated mixtures were approved as to mass formation, maximum temperature, intrusion capability and resistance to compression. Only the one containing pure cement was approved on the flexion essay. Conclusion: The addition of vancomycin and/or methylene blue to Surgical Simplex@P Stryker bone cement reduces its resistance to flexion, being unacceptable by the ABNT NBR ISO 5833 rule.

Reliable acetabular cup orientation with a new gravity-assisted guidance system.

Acetabular cup orientation is a key factor determining hip stability, and standard mechanical guides have shown little help in improving alignment. An in vitro study was carried out to compare the accuracy and precision of a new gravity-assisted guidance system with a standard mechanical guide. Three hundred ten cups were impacted by 5 surgeons, and the final cup orientation was measured. With the new guide, the average error in anteversion was 0.4 degrees , compared with 10.4 degrees with the standard guide and 0.3 degrees and -4.7 degrees , respectively, for abduction angles. The average time required for orienting the cups was similar for both guides. The accuracy and reproducibility obtained with the new guide were better (P < .0001). These good results would require a clinical validation.

Recambios en un solo tiempo de prótesis de cadera y rodilla sobre terreno contaminado: nuestra experiencia

Objective: Evaluate the results obtained in the simultaneous replacement of a septic arthroplasty or a second septic replacement (implanting the prosthesis in a contaminated eld). Material and method: Series of 17 cases, with a mean age of 66.8 years and average follow-up of 49 months. The exclusion criteria were serious immunological depression and unknown germ or not sensitive to at least three antibiotics. After the intervention, the corresponding antibiotics were administered between six weeks and three months. Recovery was established as the normality for infection indicator variables at least nine months after the replacement. Results: 14 patients developed towards total recovery (follow-up at least 9 months and maximum 84 months). 3 cases presented relapse, all three carriers of Staphylococcus epidermidis (at 1, 3 and 7 months of follow-up respectively). The success percentage is 82.41% (average follow-up of 49 months). Conclusions: Simultaneous replacements is an interesting option for patients with plural pathologies as it o"ers a single operation, less morbidity, quicker return to activities to restore normal function and less associated costs

Visual loss after orthopedic procedures.

Perioperative visual loss (PVL) is a very rare and unpredictable complication of surgery performed at distance from the visual pathways, mostly after spine or cardiac procedures. We report 6 consecutive patients with PVL after routine orthopedic procedures (osteosynthesis for complex fracture of the femur [2], total hip arthroplasty [2], hip prosthesis arthroplasty [1], bilateral simultaneous total knee arthroplasty [1]) and reviewed the literature on the subject. An ischemic optic neuropathy was diagnosed in all cases, and visual loss was bilateral in 5 of 6 patients. Partial visual improvement occurred in only 3 of 11 eyes. No specific therapy is available for PVL. Postoperative visual disturbances should prompt without delay an ophthalmic evaluation because emergent correction of anemia, systemic hypotension, or hypovolemia might improve visual prognosis of PVL.

Three-dimensional computed cementless custom femoral stems in young patients: midterm followup.

We prospectively evaluated the results of our custom cementless femoral stems to ascertain whether this technology produced reasonable clinical function, complication rates, and loosening rates at midterm. Fifty-seven consecutive patients had surgery in 62 hips for primary osteoarthritis at a mean age of 57 years using a three-dimensional computed custom cementless stem. Patients were reviewed at a mean followup of 94.9 months. At review, the mean Harris hip score was 98.8 points (range, 84-100) compared with 61.1 (range, 28-78) points preoperatively. No patient complained of thigh pain. No migration or subsidence was observed. All stems were considered stable according to the radiographic criteria defined by Engh et al. There were no dislocations, no infections, and no reoperations. Our results are comparable with published results from clinical and radiologic points of view. Two problems remain unsolved: the price of a custom stem is twice as expensive as a standard stem; and we need longer term results before definitely recommending this technology as a reasonable alternative to current arthroplasties in younger patients. The data support the continued exploration of this technology with controlled clinical followup. LEVEL OF EVIDENCE: Therapeutic study, Level II-1 (prospective cohort study). See the Guidelines to Authors for a complete description of levels of evidence.

La variabilité chirurgicale en Suisse : différences intercantonales observées pour trois interventions

En Suisse, la variabilité géographique de la consommation de soins chirurgicaux est un domaine encore inexploré. Ce rapport examine de manière descriptive trois interventions chirurgicales réalisées en Suisse entre 2003 et 2005 : la prothèse partielle ou totale de hanche, la prothèse de genou et la cure de hernie discale. Il se concentre sur les caractéristiques démographiques des patients opérés, leur diagnostic et les différences des taux d'intervention selon les cantons. Les résultats sont présentés sous forme de taux bruts, de taux standardisés et de cartes géographiques de distribution.

P value and the theory of hypothesis testing: an explanation for new researchers.

In the 1920s, Ronald Fisher developed the theory behind the p value and Jerzy Neyman and Egon Pearson developed the theory of hypothesis testing. These distinct theories have provided researchers important quantitative tools to confirm or refute their hypotheses. The p value is the probability to obtain an effect equal to or more extreme than the one observed presuming the null hypothesis of no effect is true; it gives researchers a measure of the strength of evidence against the null hypothesis. As commonly used, investigators will select a threshold p value below which they will reject the null hypothesis. The theory of hypothesis testing allows researchers to reject a null hypothesis in favor of an alternative hypothesis of some effect. As commonly used, investigators choose Type I error (rejecting the null hypothesis when it is true) and Type II error (accepting the null hypothesis when it is false) levels and determine some critical region. If the test statistic falls into that critical region, the null hypothesis is rejected in favor of the alternative hypothesis. Despite similarities between the two, the p value and the theory of hypothesis testing are different theories that often are misunderstood and confused, leading researchers to improper conclusions. Perhaps the most common misconception is to consider the p value as the probability that the null hypothesis is true rather than the probability of obtaining the difference observed, or one that is more extreme, considering the null is true. Another concern is the risk that an important proportion of statistically significant results are falsely significant. Researchers should have a minimum understanding of these two theories so that they are better able to plan, conduct, interpret, and report scientific experiments.

Réseaux de soins : une théorie en attente de pratique ? : principaux obstacles et facteurs de réussite dans la mise en place d'une nouvelle forme organisationnelle pour les interventions de prothèse totale ou partielles de hanche

La mise en place du parcours clinique pour les interventions de la prothèse totale ou partielle de la hanche (préalable à la mise en place d'un réseau de soins dans notre étude) présuppose la réalisation des objectifs suivants: - décloisonner le système de santé (en commençant avec les deux acteurs concernés) ; - mettre le patient au coeur du système ; - améliorer l'efficience du système ; - maîtriser les coûts, tout en garantissant une qualité des prestations offertes ; - instaurer une nouvelle coopération et coordination entre fournisseurs de soins, ainsi qu' - accroître les compétences et valoriser les professionnels. C'est un projet de qualité des soins. L'itinéraire est multidisciplinaire et destiné à un groupe bien précis de patients, il repose sur une planification systématique et se traduit par un programme de soins spécifiques. La réalisation de tout ou partie de ces objectifs nous permettra de confirmer ou rejeter l'hypothèse selon laquelle les réseaux de soins sont une possible réponse à la crise actuelle du système de santé. Ces affirmations sont-elles toutes nécessaires à la création d'un réseau de soins ? Sont-elles exclusives ou cumulatives ? Y-a-t-il un lien entre la réflexion théorique et les expériences vécues sur le terrain ? Ainsi, nous nous efforcerons de démont[r]er ou de rejeter ces hypothèses au fur et à mesure que nous avancerons avec notre travail de création et développement d'un réseau de soins intégrés. Ce mémoire sera aussi l'occasion de vérifier l'adéquation des théories développées depuis quelques années concernant la mise en place d'une nouvelle forme organisationnelle comme étant une des possibles réponses aux défaillances du système de santé. [Auteur, p. 13]

Contrôle postural et patron locomoteur à la suite d'une arthroplastie de la hanche : effet du type de prothèse

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Bloqueio contínuo do plexo lombar via posterior bilateral com bomba de infusão descartável: relato de caso

JUSTIFICATIVA E OBJETIVOS: O número de artroplastia total de quadril (ATQ) bilateral tem aumentado a cada ano. Analgesia pós-operatória pela infusão contínua perineural com anestésico local tem se mostrado favorável quando comparada com analgesia sistêmica. O uso de bombas elastoméricas tem aumentado a satisfação do paciente quando em comparação com os modelos eletrônicos. O objetivo deste relato foi descrever um caso de analgesia contínua bilateral do plexo lombar via posterior, com infusão contínua através de bomba elastomérica, em paciente submetido à uma artroplastia bilateral de quadril. RELATO do CASO: Paciente feminina, 46 anos, 65 kg, 162 cm, com artrite reumatoide e hipertensão arterial, estado físico ASA II, escalada para ser submetida a ATQ bilateral em um único estágio. Uso de corticosteroide por 13 anos. Hemoglobina = 10,1 g.dL-1, hematócrito = 32,7%. Monitoração de rotina. Raquianestesia com 15 mg de bupivacaína 0,5% isobárica. Anestesia geral com propofol (PFS) e remifentanil e intubação sem bloqueadores neuromusculares. ATQ direita e no final, bloqueio plexo lombar com estimulador e conjunto agulha 150 mm e injeção de 20 mL bupivacaína 0,2% e passagem de cateter. ATQ esquerda e, no final, mesmo procedimento. Estudado dispersão do anestésico e contraste. Instalado bomba elastomérica com bupivacaína 0,1% (400 mL) em velocidade de 14 mL.h-1. Transferida para Unidade de Cuidados Intensivos (UCI). Vinte e quatro horas após, nova bomba com a mesma solução. Nenhum bolus durante 50 horas. Após remoção de cateter, dor controlada por via oral com cetoprofeno e dipirona. CONCLUSÕES: O bloqueio bilateral contínuo periférico com infusão de bupivacaína a 0,1% com bombas elastoméricas é um procedimento seguro e efetivo em adultos.

An integrated approach for reconstructing surface models of the proximal femur from sparse input data for surgical navigation

A patient-specific surface model of the proximal femur plays an important role in planning and supporting various computer-assisted surgical procedures including total hip replacement, hip resurfacing, and osteotomy of the proximal femur. The common approach to derive 3D models of the proximal femur is to use imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI). However, the high logistic effort, the extra radiation (CT-imaging), and the large quantity of data to be acquired and processed make them less functional. In this paper, we present an integrated approach using a multi-level point distribution model (ML-PDM) to reconstruct a patient-specific model of the proximal femur from intra-operatively available sparse data. Results of experiments performed on dry cadaveric bones using dozens of 3D points are presented, as well as experiments using a limited number of 2D X-ray images, which demonstrate promising accuracy of the present approach.

Making minimally invasive THR safe: conclusions from biomechanical simulation and analysis.

The use of smaller surgical incisions has become popularized for total hip arthroplasty (THR) because of the potential benefits of shorter recovery and improved cosmetic appearance. However, an increased incidence of serious complications has been reported. To minimize the risks of minimally invasive approaches to THR, we have developed an experimental approach which enables us to evaluate risk factors in these procedures through cadaveric simulations performed within the laboratory. During cadaveric hip replacement procedures performed via posterior and antero-lateral mini-incisions, pressures developed between the wound edges and the retractors were approximately double those recorded during conventional hip replacement using Charnley retractors (p < 0.01). In MIS procedures performed via the dual-incision approach, lack of direct visualisation of the proximal femur led to misalignment of broaches and implants with increased risk of cortical fracture during canal preparation and implant insertion. Cadaveric simulation of surgical procedures allows surgeons to measure variables affecting the technical success of surgery and to master new procedures without placing patients at risk.

Prevalencia del síndrome de cementación ósea en pacientes de artroplastia de cadera, Hospital Universitario Mayor Méderi 2014

Resumen Introducción: Con el fin de estimar la prevalencia del síndrome de cementación ósea (SICO) en pacientes llevados a artroplastia de cadera cementada en el Hospital Universitario Mayor Méderi 2014. Materiales y métodos: Se realizó un estudio observacional, descriptivo, de corte transversal, se evaluaron los registros de historia clínica de los pacientes llevados a artroplastia cementada de cadera desde enero a diciembre de 2014. Se estimó la prevalencia del número total de casos de SICO sobre el total de intervenidos y la mortalidad del número de muertes intraoperatorias sobre el total de pacientes que desarrollaron el SICO. Resultados: Se encontraron 102 pacientes llevados a artroplastia cementada de cadera; 73,5% de género femenino, la mediana de edad fue 82 años, la prevalencia de SICO fue de 0,96 x 100 procedimientos y la mortalidad de 7,14 x 100 eventos (1 caso), el evento más frecuentemente relacionado fue las Perdida sanguínea < 300ml (p.valor: 0,006), el resto de diferencias entre los factores de riesgo reconocidos no fueron estadísticamente significativas. Discusión Se encontró una baja frecuencia del evento, con una muerte relacionada, se requieren estudios prospectivos para explorar desenlaces en el tiempo para la presentación de SICO y factores de riesgo adicionales. Palabras clave: "Hipotensión/Diagnóstico", "Prevalencia", "Artroplastia de Reemplazo de Cadera/Efectos Adversos", "Cementos Óseos/Efectos Adversos", "Complicaciones Postoperatorias/Etiología" y "Complicaciones Postoperatorias/Inducido Químicamente"