Fixation method does not affect restoration of rotation center in hip replacements: A single-site retrospective study

ABSTRACT: BACKGROUND: Aseptic loosening is one of the greatest problems in hip replacement surgery. The rotation center of the hip is believed to influence the longevity of fixation. The aim of this study was to compare the influence of cemented and cementless cup fixation techniques on the position of the center of rotation because cemented cup fixation requires the removal of more bone for solid fixation than the cementless technique. METHODS: We retrospectively compared pre- and post-operative positions of the hip rotation center in 25 and 68 patients who underwent artificial hip replacements in our department in 2007 using cemented or cementless cup fixation, respectively, with digital radiographic image analysis. RESULTS: The mean horizontal and vertical distances between the rotation center and the acetabular teardrop were compared in radiographic images taken pre- and post-operatively. The mean horizontal difference was 2.63 mm (range: -11.00 mm to 10.46 mm, standard deviation 4.23 mm) for patients who underwent cementless fixation, and 2.84 mm (range: -10.87 to 5.30 mm, standard deviation 4.59 mm) for patients who underwent cemented fixation. The mean vertical difference was 0.60 mm (range: -20.15 mm to 10.00 mm, standard deviation 3.93 mm) and 0.41 mm (range: -9.26 mm to 6.54 mm, standard deviation 3.58 mm) for the cementless and cemented fixation groups, respectively. The two fixation techniques had no significant difference on the position of the hip rotation center in the 93 patients in this study. CONCLUSIONS: The hip rotation center was similarly restored using either the cemented or cementless fixation techniques in this patient cohort, indicating that the fixation technique itself does not interfere with the position of the center of rotation. To completely answer this question further studies with more patients are needed.     

Probing the transient dark state of substrate binding to GroEL by relaxation-based solution NMR

The mechanism whereby the prototypical chaperonin GroEL performs work on substrate proteins has not yet been fully elucidated, hindered by lack of detailed structural and dynamic information on the bound substrate. Previous investigations have produced conflicting reports on the state of GroEL-bound polypeptides, largely due to the transient and dynamic nature of these complexes. Here, we present a unique approach, based on combined analysis of four complementary relaxation-based NMR experiments, to probe directly the “dark” NMR-invisible state of the model, intrinsically disordered, polypeptide amyloid β (Aβ40) bound to GroEL. The four NMR experiments, lifetime line-broadening, dark-state exchange saturation transfer, relaxation dispersion, and small exchange-induced chemical shifts, are dependent in different ways on the overall exchange rates and populations of the free and bound states of the substrate, as well as on residue-specific dynamics and structure within the bound state as reported by transverse magnetization relaxation rates and backbone chemical shifts, respectively. Global fitting of all the NMR data shows that the complex is transient with a lifetime of <1 ms, that binding involves two predominantly hydrophobic segments corresponding to predicted GroEL consensus binding sequences, and that the structure of the bound polypeptide remains intrinsically and dynamically disordered with minimal changes in secondary structure propensity relative to the free state. Our results establish a unique method to observe NMR-invisible dynamic states of GroEL-bound substrates and to describe at atomic resolution the events between substrate binding and encapsulation that are crucial for understanding the normal and stress-related metabolic function of chaperonins.     

Is impingement the cause of jumper's knee? Dynamic and static magnetic resonance imaging of patellar tendinitis in an open-configuration system

BACKGROUND: Chronic overload is considered the main cause of patellar tendinitis, but it has been postulated that impingement of the inferior patellar pole against the patellar tendon during knee flexion could be responsible. HYPOTHESIS: The role of the patellar pole in patellar tendinitis can be determined by dynamic magnetic resonance imaging. STUDY DESIGN: Case-control study. METHODS: We compared 19 knees with patellar tendinitis and 32 asymptomatic knees of age-matched subjects using an open-configuration magnetic resonance imaging system. Dynamic sagittal images were obtained from full extension to 100 degrees of flexion with and without activation of the quadriceps muscle. The following measurements were made from the images: tendon-patella angle, anteroposterior diameter of the tendon, signal difference-to-noise ratio, the shape of the inferior patellar pole, and the location of the patellar tendon insertion. RESULTS: The tendon-patella angle was not significantly different between groups at any flexion angle, with or without quadriceps muscle activation. The insertion site of the patellar tendon differed significantly but not the shape of the inferior pole of the patella. The volume and the signal difference-to-noise ratio of zones of increased intratendinous signal as well as the anteroposterior diameter of the proximal patellar tendon were increased in symptomatic knees. CONCLUSIONS: The relationship between the patella and the patellar tendon was identical in both groups; therefore, chronic overload seems to be a major cause of patellar tendinitis.     

The effectiveness of polyethylene versus titanium particles in inducing osteolysis in vivo.

Bearing surface wear and periprosthetic osteolysis due to wear particles are among the most common reasons for joint replacement failure. A murine calvarial model of wear particle-induced osteolysis has been used to identify different biologic factors associated with this problem and to test nonsurgical methods of modulating the host response to particulate debris. This model has utilized titanium particles, however, in clinical practice the most common source of particulate debris is polyethylene particles from bearing surface wear. We now report a calvarial model of wear particle-induced osteolysis based on commercially available polyethylene particles. We found that compared to sham surgery osteoclast recruitment and bone resorption can be induced by introduction of the titanium particles or polyethylene particles. However, bone resorption was significantly higher with polyethylene particles compared to titanium particles (p=0.02). We consider the polyethylene based murine calvarial model of wear particle-induced osteolysis a reliable and clinically relevant tool to understand the host factors and potential pharmacologic interventions that can influence wear debris generated osteolysis. This model might serve as an extension of the well-established titanium based bone resorption model.     

Paediatric trauma mortality in Norway: A population-based study of injury characteristics and urban-rural differences

IntroductionPaediatric injury is a major global public health challenge. Epidemiological research is required for effective primary injury prevention and to develop trauma systems for optimal management of childhood injuries. This study aimed to describe the characteristics and geographical distribution of paediatric trauma deaths and to assess the relationship between rural locations and mortality rates.Materials and methodsBy accessing national registries, all trauma related deaths of persons aged 0–15 years in Norway from 1998 to 2007 were included. Paediatric trauma mortality rates and injury characteristic were analysed in relation to three different measures of municipal rurality: centrality, population density and settlement density.ResultsThere were 462 trauma related deaths during the study period and the national annual paediatric mortality rate was 4.81/100 000. Rural areas had higher mortality rates, and this difference was best predicted by municipal centrality. Rural trauma was characterised by traffic accidents and deaths that occurred prior to reaching hospital. The rural and northernmost county, Finnmark, had a mortality rate three times the national average.ConclusionMortality rates after childhood injury are high in rural areas. Substantiated measures of rurality are required for optimal allocation of primary and secondary preventive measures.     

Soft Tissue Management in Open Fractures of the Lower Leg: The Role of Vacuum Therapy

Abstract   The management of severe open fractures of the lower leg continues to challenge the treating surgeon. Major difficulties include high infection rates as well as adequate temporary soft tissue coverage. In the past, these injuries were commonly associated with loss of the extremity. Today, vacuum therapy provides not only safe temporary wound coverage but also conditioning of the soft tissues until definitive wound closure. Amongst other advantages, bacterial clearance and increased formation of granulation tissue are attributed to vacuum therapy, making it an extremely attractive tool in the field of wound healing. However, despite its clinical significance, which is underlined by a constantly increasing range of indications, there is a substantial lack of basic research and well-designed studies documenting the superiority of vacuum therapy compared to alternative wound dressings. Vacuum therapy has been approved as an adjunct in the treatment of severe open fractures of the lower leg, complementing repeated surgical debridement and soft tissue coverage by microvascular flaps, which are still crucial in the treatment of these limb-threatening injuries. Vacuum therapy has in general proven useful in the management of soft tissue injuries and, since it is generally well tolerated and has low complication rates, it is fast becoming the gold standard for temporary wound coverage in the treatment of severe open fractures of the lower leg.     

Correlation between [18F]FDG PET/CT and volume perfusion CT in primary tumours and mediastinal lymph nodes of non-small-cell lung cancer

Purpose

The aim of this study was to investigate correlations between glucose metabolism as determined by [¹⁸F]FDG PET/CT and tumour perfusion as quantified by volume perfusion CT in primary tumours and mediastinal lymph nodes (MLN) of patients with non-small-cell lung cancer (NSCLC).

Methods

Enrolled in the study were 17 patients with NSCLC. [¹⁸F]FDG uptake was quantified in terms of SUV_max and SUV_avg. Blood flow (BF), blood volume (BV) and flow extraction product (K^trans) were determined as perfusion parameters. The correlations between the perfusion parameters and [¹⁸F]FDG uptake values were subsequently evaluated.

Results

For the primary tumours, no correlations were found between perfusion parameters and [¹⁸F]FDG uptake. In MLN, there were negative correlations between BF and SUV_avg (r?=??0.383), BV and SUV_avg (r?=??0.406), and BV and SUV_max (r?=??0.377), but not between BF and SUV_max, K^trans and SUV_avg, or K^trans and SUV_max. Additionally, in MLN with SUV_max >2.5 there were negative correlations between BF and SUV_avg (r?=??0.510), BV and SUV_avg (r?=??0.390), BF and SUV_max (r?=??0.536), as well as BV and SUV_max (r?=??0.346).

Conclusion

Perfusion and glucose metabolism seemed to be uncoupled in large primary tumours, but an inverse correlation was observed in MLN. This information may help improve therapy planning and response evaluation.     

Prophylaxis of Heterotopic Ossification in Patients Sedated after Polytrauma

BACKGROUND AND PURPOSE: Heterotopic ossification (HO) often follows acetabular fractures after multitrauma. Irradiation is a mean for prophylaxis. We established a standard procedure in our hospital for patients under sedation, when obtaining informed consent for HO prophylaxis is impossible. PATIENTS AND METHODS: We reviewed current scientific evidence, calculated the risks of radiation and presented the ethical and legal framework. The subject was scrutinised by an interdisciplinary panel. RESULTS: Irradiation is the most effective means for prophylaxis and has few adverse effects in adult patients with fractures of the acetabulum. The lifetime risk of radiation-induced cancer or infertility are insignificant. CONCLUSIONS: Informed consent for irradiation should be obtained before operation whenever possible. When this cannot be done prophylaxis can be postponed for a maximum of 3 days in order to obtain consent. If the patient is not able to communicate within this period, prophylactic irradiation should be given after consulting the relatives. The patient must be informed as soon as possible.