Mechanical strain promotes osteogenic differentiation of mesenchymal stem cells on TiO2 nanotubes substrate.

Previous studies demonstrated cycle mechanical strain induced osteogenic differentiation of MSCs. But in general, MSCs are typically seeded on a flexible membrane or within a soft matrix. TiO2 nanotubes substrate topography plays a critical role in promoting the MSCs response and affects MSCs fate. Titanium implants surface modified by TiO2 nanotubes topography provides the opportunity to improve osseointegration by additionally regulating the MSCs fate. Titanium is one of most commonly used materials in the orthopedics and can undergo elastic deformation under certain mechanical stress. Therefore, for clinic trails, it is necessary to investigate the effect of mechanical strain on osteogenesis of MSCs on TiO2 nanotubes modified titanium substrate. But until now, there has been no research focused on the relationship between mechanical strain and osteogenesis of MSCs on the TiO2 nanotubes topography substrate. Here, we firstly applied the mechanical stress to the TiO2 nanotubes modified titanium specimen to investigate the effects of mechanical strain on the biological behaviors of MSCs. Our present study showed that mechanical strain promoted cell proliferation, spreading and increased vinculin expression of MSCs on the TiO2 nanotubes substrate. Additionally, mechanical strain enhanced the ALP activity and osteogenesis genes expression such as Runx2, BSP, ALP, OPN and OCN. Our results preliminarily demonstrated that mechanical strain enhanced the osteogenic differentiation of MSCs through the FAK-Erk1/2-Runx2 pathway on the TiO2 nanotubes substrate.

Posterosuperior Placement of a Standard-Sized Cup at the True Acetabulum in Acetabular Reconstruction of Developmental Dysplasia of the Hip With High Dislocation.

BACKGROUND: We sought to evaluate posterosuperior placement of the acetabular component at the true acetabulum during acetabular reconstruction in patients with Crowe type-IV developmental dysplasia of the hip. METHODS: Using pelvic computed tomography and image processing, we developed a two-dimensional mapping technique to demonstrate the distribution of preoperative three-dimensional cup coverage at the true acetabulum, determined the postoperative location of the acetabular cup, and calculated postoperative three-dimensional coverage for 16 Crowe type-IV dysplastic hips in 14 patients with a mean age of 52 years (33-78 years) who underwent total hip arthroplasty. Mean follow-up was 6.3 years (5.5-7.3 years). RESULTS: On preoperative mapping, the maximum three-dimensional coverage using a 44-mm cup was 87.31% (77.36%-98.14%). Mapping enabled the successful replacement of 16 hips using a mean cup size of 44.13 mm (42-46 mm) with posterosuperior placement of the cup. Early weight-bearing and no prosthesis revision or loosening during follow-up were achieved in all patients. The postoperative two-dimensional coverage on anteroposterior radiographs and three-dimensional coverage were 96.15% (89.49%-100%) and 83.42% (71.81%-98.50%), respectively. CONCLUSION: This technique may improve long-term implant survival in patients with Crowe-IV developmental dysplasia of the hip undergoing total hip arthroplasty by allowing the use of durable bearings, increasing host bone coverage, ensuring initial stability, and restoring the normal hip center.

Nickel-Titanium Shape-Memory Sawtooth-Arm Embracing Clamp for Complex Femoral Revision Hip Arthroplasty.

PURPOSES: To examine the clinical outcomes of patients treated with a nickel-titanium shape-memory sawtooth-arm embracing clamp (Ni-Ti SSEC) in complex femoral revision surgery. METHODS: We retrospectively evaluated the outcomes for 21 complex femoral revision hip arthroplasties that we treated using an Ni-Ti SSEC. The Ni-Ti SSEC was used for various procedures, including the fixation of extremely long cortical windows (11 patients), femoral shaft osteotomy (4 patients), an extended trochanteric osteotomy (3 patients), and protection of a penetrated femoral cortex by a primary stem (3 patients). All patients received follow-up care for an average of 48.2 months. RESULTS: The mean time of Ni-Ti SSEC insertion intraoperatively was 6 minutes. The mean Harris Hip Score improved from 21.2 points before revision surgery to 83.1 points at the most recent examination. No implant failures or malunions occurred. Dislocation and deep infection occurred in 1 case during the follow-up period. CONCLUSIONS: Our results show that the embracing clamp is a simple and valid method for fixing osteotomies in treating complex femoral revision surgery.

Computer simulation of optimal lipped polyethylene liner orientation against prosthetic impingement.

BACKGROUND: Lipped or elevated acetabular liners are to improve posterior stability and are widely used in hip arthroplasty. However, concerns of increasing impingement exist when using such liners and optimal orientation of the elevated rim remains unknown. We aimed to identify the impact of lipped liner on the range of motion (ROM) before impingement and propose its optimal orientation. METHODS: An isochoric three-dimensional model of a general hip-replacement prosthesis was generated, and flex-extension, add-abduction and axial rotation were simulated on a computer. The maximum ROM of the hip was measured before the neck impinged on the liner. Different combinations of acetabular anteversion angles ranging from 5 to 30 degrees, and lipped liner orientations from posterior to anterior were tested. RESULTS: When acetabular anteversion was 10 or 15 degrees, placing the lip of the liner in the posterosuperior of the acetabulum allowed satisfactory ROM in all directions. When acetabular anteversion was 20 degrees, extension and external rotation were restricted. Adjusting the lip to the superior restored satisfactory ROM. When acetabular anteversion was 25 degrees, only placing the lip into the anterosuperior could increase extension and external rotation to maintain satisfactory ROM. CONCLUSIONS: This study showed that optimal lipped liner orientation should depend on acetabular anteversion. When acetabular anteversion was smaller than 20 degrees, placing lip in the posterior allowed an optimally ROM. When acetabular anteversion was greater than 20 degrees, adjusting lip to the anterior allowed a comprehensive larger ROM to avoid early impingement.

The use of morselized allografts without impaction and cemented cage support in acetabular revision surgery: a 4- to 9-year follow-up.

BACKGROUND: Acetabular revision arthroplasty with major bone loss is one of the most difficult operations in orthopedic surgery. The goal of the study was to evaluate midterm clinical results of the use of morselized allografts with cemented cage support in revision total hip replacement. METHODS: We identified 28 patients (29 hips) at an average follow-up of 73 months. Harris Hip Scores (HHS) were assessed before and after surgery. Pre- and postoperative radiographs were evaluated for restoration of the center of rotation, component migration, and graft incorporation. RESULTS AND DISCUSSION: At follow-up, the mean HHS improved from 34 (range, 20-45) to 80 (range, 71-98) points. None of the components had been re-revised. On average, the revised hip center of rotation was improved significantly. Incorporation of the graft was complete in 23 hips. The midterm result of cage reconstruction with morselized bone allograft is relatively better than other studies using a similar cage construction. We believe we have three special modifications of this reconstruction technique that are beneficial for bone incorporation. CONCLUSIONS: These data confirm that acetabular reconstruction using morselized allografts and cemented acetabular cages is effective in the midterm as a treatment for acetabular loosening with massive bone deficiency.

Human bone marrow-derived stromal cells cultured with a plasma sprayed CaO-ZrO2-SiO2 coating.

The CaO-ZrO2-SiO2 (CZS) coating was prepared by plasma-spraying chemically synthesized CZS powder onto a Ti-6Al-4V substrate. This CZS coating has been demonstrated to have good bioactivity, high bonding strength with the substrate and a low degradation rate. However, the effect of CZS coating on the osseointegration of bone-implant is still unknown. In this study, human bone marrow-derived stromal cells (hBMSCs) were cultured on CZS coating in vitro, and cell behavior was investigated, with the classical hydroxyapatite (HA) coating as a control. Scanning electron microscopy (SEM) and immunofluorescence studies showed that the hBMSCs on the CZS coating spread well with organized cytoskeleton structure at 24 h following cell seeding. The MTT assay and the Alamar Blue assay indicated that CZS coating promoted the attachment and proliferation of hBMSCs. The results of alkaline phosphatase (ALP) activity test and the expression of osteogenic marker genes, such as ALP, collagen I (COLI), osteopontin (OPN), and osteocalcin (OCN), demonstrated that the osteoblastic differentiation of hBMSCs was enhanced more by CZS coating than by HA coating. These results suggest that CZS coating possess excellent biological properties and may have potential in biomedical applications.