Primary stability of a press-fit cup in combination with impaction grafting in an acetabular defect model

The objectives of this study were to (a) assess primary stability of a press-fit cup in a simplified acetabular defect model, filled with compacted cancellous bone chips, and (b) to compare the results with primary stability of a press-fit cup combined with two different types of bone graft substitute in the same defect model. A previously developed acetabular test model made of polyurethane foam was used, in which a mainly medial contained defect was implemented. Three test groups (N = 6 each) were prepared: Cancellous bone chips (bone chips), tricalciumphosphate tetrapods + collagen matrix (tetrapods + coll), bioactive glass S53P4 + polyethylene glycol-glycerol matrix (b.a.glass + PEG). Each material was compacted into the acetabulum and a press-fit cup was implanted. The specimens were loaded dynamically in the direction of the maximum resultant force during level walking. Relative motion between cup and test model was assessed with an optical measurement system. At the last load step (3000 N), inducible displacement was highest for bone chips with median [25th percentile; 75th percentile] value of 113 [110; 114] µm and lowest for b.a.glass + PEG with 91 [89; 93] µm. Migration at this load step was highest for b.a.glass + PEG with 868 [845; 936] µm and lowest for tetrapods + coll with 491 [487; 497] µm. The results show a comparable behavior under load of tetrapods + coll and bone chips and suggest that tetrapods + coll could be an attractive alternative to bone chips. However, so far, this was found for one specific defect type and primary stability should be further investigated in additional/more severe defects

Standardization of hemipelvis alignment for in vitro biomechanical testing

Although in vitro biomechanical tests are regularly performed, the definition of a suitable reference frame for hemipelvic specimens is still a challenge. The aims of the present study were to: (i) define a reference frame for the human hemipelvis suitable for in vitro applications, based on robust anatomical landmarks; (ii) identify the alignment of a hemipelvis based on the alignment of a whole pelvis (including right/left and male/female differences); (iii) identify the relative alignment of the proposed in vitro reference frame with respect to a reference frame commonly used in gait analysis; (iv) create an in vitro alignment procedure easy, robust and inexpensive; (v) quantify the intra-operator repeatability and inter-operator reproducibility of the procedure. A procedure to univocally identify the anatomical landmarks was created, exploiting the in vitro accessibility of the specimen's surface. Through the analysis on 53 CT scans (106 hemipelvises), the alignment of the hemipelvis based on the alignment of a whole pelvis was analyzed: differences between male/female and right/left hemipelvises were not statistically significant To overcome the uncertainty in the identification of the acetabular rim, a standard acetabular plane was defined. An alignment procedure was developed to implement such anatomical reference frame. The intra-operator repeatability and the inter-operator reproducibility were quantified with four operators, on male and female hemipelvises. The intra-operator repeatability was better than 1.5\ub0. The inter-operator reproducibility was better than 2.0\ub0. Alignment in the transverse plane was the most repeatable. The presented procedure to align hemipelvic specimens is sufficiently robust, standardized, and accessible. \ua9 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1645\u20131652, 2018

Primary stability of a press‐fit cup in combination with impaction grafting in an acetabular defect model

The objectives of this study were to (a) assess primary stability of a press-fit cup in a simplified acetabular defect model, filled with compacted cancellous bone chips, and (b) to compare the results with primary stability of a press-fit cup combined with two different types of bone graft substitute in the same defect model. A previously developed acetabular test model made of polyurethane foam was used, in which a mainly medial contained defect was implemented. Three test groups (N = 6 each) were prepared: Cancellous bone chips (bone chips), tricalciumphosphate tetrapods + collagen matrix (tetrapods + coll), bioactive glass S53P4 + polyethylene glycol-glycerol matrix (b.a.glass + PEG). Each material was compacted into the acetabulum and a press-fit cup was implanted. The specimens were loaded dynamically in the direction of the maximum resultant force during level walking. Relative motion between cup and test model was assessed with an optical measurement system. At the last load step (3000 N), inducible displacement was highest for bone chips with median [25th percentile;75th percentile] value of 113 [110;114] mu m and lowest forb.a.glass + PEGwith 91 [89;93] mu m. Migration at this load step was highest forb.a.glass + PEGwith 868 [845;936] mu m and lowest fortetrapods + collwith 491 [487;497] mu m. The results show a comparable behavior under load oftetrapods + colland bone chips and suggest thattetrapods + collcould be an attractive alternative to bone chips. However, so far, this was found for one specific defect type and primary stability should be further investigated in additional/more severe defects

Serum levels of soluble CD30 in chronic hepatitis B virus infection

There is evidence that both cellular and humoral components of the Immune response are required for viral clearance to occur in chronic hepatitis B. Recent studies demonstrated that CD30 molecule, a member of the turnout necrosis factor superfamily of membrane cytokine receptors, is expressed on, and released as a soluble molecule (sCD30) by activated T cells producing T helper 2 (Th2) cytokines, which modulate antibody responses. To better characterize the immunoregulatory mechanisms in chronic hepatitis B virus (HBV) infection, sCD30 values were evaluated by an ELISA in 90 hepatitis B surface (HBsAg)-positive patients with chronic hepatitis, selected on the basis of active viral replication and biochemical activity. At presentation abnormal levels ( gt 20 U/ml) of sCD30 were detected in 57 (63%) out of 90 patients with chronic hepatitis B, and median value was significantly higher in this group of patients compared with that of healthy HBsAg carriers (26.7 versus 10.5 U/ml, P lt 0.00005) and with normal controls (26.7 versus 3 U/ml, P lt 0.00001). Sequential studies of chronic hepatitis B did confirm the association of raised sCD30 levels with the active phase of the illness. On the other hand, a significant decrease was noted when sCD30 levels at diagnosis and after termination of HBV replication and biochemical remission of hepatitis were compared in 10 untreated patients (median, 28 U/ml at entry versus 8 U/ml at remission, P lt 0.01) and in six patients responding to interferon-alpha therapy (median, 29.5 U/ml at entry versus 6 U/ml at remission, P lt 0.05). The high serum sCD30 levels reported during the active phase of HBsAg-positive chronic hepatitis suggest a certain degree of immune competence of these patients, at least with respect to a Th2-type response. These data are in agreement with recent serologic surveys showing that most chronic hepatitis B patients do demonstrate ongoing humoral immune response to HBV antigens, using novel immunoassays designed to detect antibody in the presence of excess serum viral antigen. Th2 functions that mainly promote humoral immunity to HBV antigens may be critical, in association with a competent virus-specific cytotoxicity, for efficient termination of HBV replication in chronic hepatitis B