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Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_9 | Pages 2 - 2
1 Jun 2021
Tang H Wang S Zhou Y Li Y Zhao Y Shi H
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Introduction

The functional ante-inclination (AI) of the cup after total hip arthroplasty (THA) is a key component in the combined sagittal index (CSI) to predict joint stability after THA. To accurately predict AI, we deducted a mathematic algorithm between the radiographic anteversion (RA), radiographic inclincation (RI), pelvic tilting (PT), and AI. The current study aims (1) to validate the mathematic algorithm; (2) to convert the AI limits in the CSI index (standing AI ≤ 45°, sitting AI ≥ 41°) into coronal functional safe zone (CFSZ) and explore the influences of the stand-to-sit pelvic motion (PM) and pelvic incidence (PI) on CFSZ; (3) to locate a universal cup orientation that always fulfill the AI criteria of CSI safe zone for all patients or subgroups of PM(PM ≤ 10°, 10° < PM ≤ 30°, and PM > 30°) and PI (PI≤ 41°, 41°< PI ≤ 62°, and PI >62°), respectively.

Methods

A 3D printed phantom pelvic model was designed to simulate changing PT values. An acetabular cup was implanted with different RA, RI, and PT settings using robot assisted technique. We enrolled 100 consecutive patients who underwent robot assisted THA from April, 2019 to June, 2019 in our hospital. EOS images before THA and at 6-month follow-up were collected. AI angles were measured on the lateral view radiographs as the reference method. Mean absolute error (MAE), Bland-Altman analysis and linear regression were conducted to assess the accuracy of the AI algorithm for both the phantom and patient radiographic studies. The 100 patients were classified into three subgroups by PM and PI, respectively. Linear regression and ANOVA analysis were conducted to explore the relationship between the size of CFSZ, and PM and PI, respectively. Intersection of the CFSZ was conducted to identify if any universal cup orientation (RA, RI) existed for the CSI index.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_2 | Pages 105 - 105
1 Feb 2020
Friedrich C Wang S Francis A Baker E
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Prior work in the setting of MRSA (clinical isolate), showed that enhancement of Ti6Al4V with anodized nanotubes apparently disrupts the formation and adhesion of MRSA biofilm. The greater amount of cultured MRSA using effluent released from in vitro nanotube surfaces by sonication, compared with thermal plasma sprayed (TPS), indicated probable disruption of biofilm formation and adhesion. The use of nanosilver nanotubes in vivo in a rabbit model showed that after 1 week of infection followed by 1 week of vancomycin treatment, the nanotube MRSA level was 30% that of TPS, and the nanosilver nanotube MRSA level was only 5% of TPS. The implementation of the technology will enhance the remodeled bone locking ability of rough TPS, with surface nanotubes that provide antibacterial properties and increased bone adhesion.

Lap shear tests of the nanotubes were performed according to ASTM F1044. In multiple tests, circular adhesive films bonded Ti6Al4V bars containing nanotubes with plain Ti6Al4V. The assemblies were suitably arranged in a tensile tester and pulled to shear failure. There were three modes of failure; shear failure within the adhesive, failure of the adhesive from the plain titanium, and shear failure of the nanotubes from the bar. Tests determined the shear strength of the adhesive and its bonding strength to bare titanium. ImageJ software determined the area of each of the three failure modes. From this analysis, the shear strength of the nanotubes of each sample was calculated.

The analyses showed the shear strength of the nanotubes to be as high as 65MPa (9,500psi) with a more typical shear strength of 55MPa (8,000 psi), and several surfaces with 45MPa (6,000 psi). The literature presents models predicting the shear stress in bonded hip stems. Assuming the TPS with nanotubes performs similar to a bonded hip stem, owing to the locking of the bone with the TPS, a typical shear stress prediction for physiological loads is approximately 10 MPa. The nanotube shear strengths were 4–6 times higher than the expected stress during use.

For any figures or tables, please contact authors directly.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVIII | Pages 2 - 2
1 Sep 2012
Li R Qamirani E Atesok K Nauth A Wang S Li C Schemitsch EH
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Purpose

Angiogenesis and osteogenesis are essential for bone growth, fracture repair, and bone remodeling. VEGF has an important role in bone repair by promoting angiogenesis and osteogenesis. In our previous study, endothelial progenitor cells (EPCs) promoted bone healing in a rat segmental bone defect as confirmed by radiological, histological and microCT evaluations (Atesok, Li, Schemitsch 2010); EPC treatment of fractures resulted in a significantly higher strength by biomechanical examination (Li, Schemitsch 2010). In addition, cell-based VEGF gene transfer has been effective in the treatment of segmental bone defects in a rabbit model (Li, Schemitsch et al 2009); Purpose of this study: Evaluation of VEGF gene expression after EPC local therapy for a rat segmental bone defect.

Method

Rat bone marrow-derived EPCs were isolated from the rat bone marrow by the Ficoll-paque gradient centrifuge technique. The EPCs were cultured for 7 to 10 days in endothelial cell growth medium with supplements (EGM-2-MV-SingleQuots, Clonetics). and collected for treatment of the rat segmental bone defect. EPCs were identified by immunocytochemistry staining with primary antibodies for CD34, CD133, FLK-1, and vWF. A total of fifty six rats were studied. A five millimeter segmental bone defect was created in the middle 1/3 of each femur followed by mini plate fixation. The treatment group received 1×106 EPCs locally at the bone defect and control animals received saline only. Seven control and seven EPC treated rats were included in each group at 1, 2, 3 and 10 weeks. Animals were sacrificed at the end of the treatment period, and specimens from the fracture gap area were collected and immediately frozen. Rat VEGF mRNA was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by VisionWorksLS. All measurements were performed in triplicate.