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Modulation of macrophage polarization and prevention of CCL2-induced macrophage chemotaxis are emerging strategies to reduce wear particle induced osteolysis and aseptic total joint replacement loosening. In this study, the effect of continuous IL-4 delivery or bioactive implant coating that constitutively releases a protein inhibitor of CCL2 signaling (7ND) on particle induced osteolysis were studied in the murine continuous femoral intramedullary particle infusion model. Polyethylene particles with or without IL-4 were infused into mouse distal femurs implanted with hollow titanium rods using subcutaneous infusion pumps. In another experimental group, particles were infused into the femur through a 7ND coated rod. After 4 weeks, fixation of the implant was assessed using a pullout test. The volume of trabecular bone and the geometry of the local cortical bone were assessed by µCT and the corresponding structural properties of the cortical bone determined by torsional testing. Continuous IL-4 delivery led to increased trabecular bone volume as well as enhanced local bone geometry and structural properties, while 7ND implant coating did not have effect on these parameters. The results suggest that local IL-4 treatment is a promising strategy to mitigate wear particle induced osteolysis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2255-2262, 2016., (© 2016 Wiley Periodicals, Inc.)

The present study examined the bone bonding strength of diamond-structured porous titanium-alloy (Porous-Ti-alloy) manufactured using the electron beam-melting technique in comparison with fiber mesh-coated or rough-surfaced implants. Cylindrical implants with four different pore sizes (500, 640, 800, and 1000μm) of Porous-Ti-alloy, titanium fiber mesh (FM), and surfaces roughened by titanium arc spray (Ti-spray) were implanted into the distal femur of rabbits. Bone bonding strength and histological bone ingrowth were evaluated at 4 and 12weeks after implantation. The bone bonding strength of Porous-Ti-alloy implants (640μm pore size) increased over time from 541.4N at 4weeks to 704.6N at 12weeks and was comparable to that of FM and Ti-spray implants at both weeks. No breakage of the porous structure after mechanical testing was found with Porous-Ti-alloy implants. Histological bone ingrowth that increased with implantation time occurred along the inner structure of Porous-Ti-alloy implants. There was no difference in bone ingrowth in Porous-Ti-alloy implants with pore sizes among 500, 640, and 800μm; however, less bone ingrowth was observed with the 1000μm pore size. These results indicated Porous-Ti-alloy implants with pore size under 800μm provided biologically active and mechanically stable surface for implant fixation to bone, and had potential advantages for weight bearing orthopedic implants such as acetabular cups., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Anteversion of an acetabular component often is difficult to ascertain in patients with THA in whom excessively anteverted or retroverted femurs may result in limited ROM or risk of dislocation. Restriction of motion, however, is determined by the combination of version of both components., Questions/purposes: We therefore determined the combined anteversion values that provide adequate ROM. We varied acetabular version by differing implantations and varied femoral version with modular necks., Methods: ROM was tested by changing cup anteversion after setting the femoral version to 20° or 60° anteversion or 20° retroversion. The angle of the modular neck was adjusted in 11 increments of 5° each. Range of internal rotation (IR) at 90° flexion, external rotation (ER) at 0° extension, and flexion (Flex) were measured when any impingement occurred before dislocation. We defined a required ROM as having 40° IR, 30° ER, and 110° Flex., Results: At 60° anteversion, ER was less than 10° even when the acetabular component was set at 10° retroversion because of posterior impingement. When a modular neck with 25° retroversion was used, ER improved to greater than 30°. At 20° retroversion, IR was 31° even when the acetabular component was opened to 35° anteversion. IR improved to 34° and 40° with 20° and 25° anteverted modular necks, respectively., Conclusions and Clinical Relevance: In cases with excessive femoral anteversion or retroversion, the required ROM could not be achieved by simply changing the version of acetabular components. The adjustment of femoral versions using the modular necks allowed additional improvement of ROM.

Objective: Morphological correlation between the acetabulum and femur at the hip joint is still controversial. We tested the hypothesis that femoral anteversion correlates with acetabular version and coverage in patients with developmental dysplasia of the hip (DDH). Materials and methods: Using pelvic computed tomography (CT) images of 79 hips in 49 Asian women with DDH and 49 normal hips, we measured femoral anteversion, the axial and vertical acetabular version and the acetabular sector angle (ASA) to demarcate femoral head coverage. Depending on the location of the acetabular bone defect, dysplastic hips were divided into three subgroups: the anterior, global and posterior deficiency groups. We performed a comparative analysis between dysplastic and normal hips using the Wilcoxon rank sum test, and a relative analysis between femoral anteversion and acetabular measurements in dysplastic hips using Pearson's correlation coefficient. Results: The amount of femoral anteversion in dysplastic hips was greater and more variable than in normal hips ( p < 0.0001, p = 0.0277 respectively). Femoral anteversion in dysplastic hips correlated significantly with acetabular anteversion in the groups with anterior and global deficiency subgroups ( p < 0.05, r = 0.2990, p < 0.05, r = 0.451 respectively), but not with the posterior deficiency subgroup. Femoral anteversion also correlated with vertical acetabular version. When acetabular coverage was examined, significant correlations were noted between femoral anteversion and anterior and superior coverage, but not with posterior coverage. These correlations were not observed in normal hips. Conclusions: Our results showed significantly greater and more variable femoral anteversion in DDH, and a significant correlation between femoral anteversion and acetabular version and coverage in DDH with anterior and global acetabular bone deficiency. [ABSTRACT FROM AUTHOR]

Background: The rotational position of the acetabulum to the pelvis (acetabular tilt) may influence acetabular version and coverage of the femoral head. To date, the pathologic significance of acetabular tilt in hip dysplasia is unknown. Questions/Purposes: We determined whether acetabular tilt in hip dysplasia is different from that in normal hips and whether this correlates with acetabular version and coverage. Methods: We measured the acetabular tilt angle on the lateral view of three-dimensional pelvic CT images of 40 patients (72 hips) with hip dysplasia. Forty normal hips from 40 patients were used as controls. The acetabular sector angle was measured as an index for acetabular coverage of the femoral head. Results: The mean acetabular tilt angle was increased in dysplastic hips compared with controls. In dysplastic hips, a posteriorly rotated acetabulum (increased acetabular tilt) was associated with increased acetabular anteversion and with decreased anterior and anterosuperior acetabular coverage. No correlation was found in controls. In dysplastic hips with a posterior acetabular deficiency, the acetabulum was rotated anteriorly (decreased acetabular tilt) compared with hips with anterior and lateral deficiencies. Conclusions: We observed a correlation between the rotational position of the acetabulum in the pelvis with acetabular version and coverage in hip dysplasia. Our observations confirmed anterior rotation of the acetabular fragment during periacetabular osteotomies is an anatomically reasonable maneuver for hips with anterolateral acetabular deficiencies, while the maneuver can exacerbate posterior coverage and should be avoided in hips with a posterior acetabular deficiency. Level of Evidence: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]