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The gold standard treatment in anterior cruciate ligament (ACL) reconstruction involves autologous tissue transplantation, but this can have complications. Artificial grafts are an alternative, but the best option is debated. This study aimed to assess the biocompatibility and integration of a silk fibroin textile prosthesis (SF-TP) with peri-implant bone tissue and the native ACL. Twenty-six sheep underwent ACL reconstruction with SF-TP or autologous femoral fascia lata (FFL). Sheep were divided into two groups (3 and 6 months) and retrieved joints processed for histological, morphometrical and mechanical analysis. In vitro, SF-TP showed no cytotoxicity and good cell interaction up to 14 days. Histology revealed fibro-vascular tissue around SF-TP, with a progressive attempt of ligamentous-like tissue formation at 6 months. However, SF-TP group had higher joint damage scores. Micro-CT showed tunnel enlargement in SF-TP group, while FFL group had a decrease. SF-TP reconstructions had lower stiffness and strength (44 % and 64 % decrease) than those of autologous FFL reconstruction and often failed by pull-out from the bone tunnel due to tunnel enlargement. These results indicate poor osteointegration and graft motion with SF-TP, leading to joint damage/bone resorption and reduced mechanical competence. These results do not support the use of SF-TP for ACL reconstruction., Competing Interests: Declaration of competing interest The authors of the IRCCS Istituto Ortopedico Rizzoli declare that their research activity was conducted through an industrial research contract signed with Innovhub - Stazioni Sperimentali per l'Industria. The other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Chiara E. Ghezzi worked at Politecnico di Milano when the project was executed. A. Alessandrino was employed at Stazione Sperimentale per la Seta and G. Freddi was employed at Innovhub - Stazioni Sperimentali per l'Industria when the project was executed. Currently, A. A. and G. F. are founders and stock owners of Silk Biomaterials S.r.l., (Copyright © 2024 Elsevier B.V. All rights reserved.) more...

Purpose: Many treatment options are available for the revision of large acetabular defects. Debate continues as to which technique is most effective. This meta-analysis aimed to determine the rates of failure of acetabular bone defects Paprosky type III or American Academy of Orthopaedic types III-IV treated with morselized allograft in association with cemented cup or cementless cup or reinforcement devices., Methods: The US National Library of Medicine (PubMed/MEDLINE), EMBASE and the Cochrane Database of Systematic Reviews were queried for publications from January 1980 to 1 April 2024 utilizing keywords pertinent to total hip arthroplasty (THA), acetabular impaction bone grafting and revision THA. The main outcome measure was the 9-year implant failure rate., Results: Thirty-nine articles were eligible for inclusion in the current study. We found 41 treatment approaches that we grouped into three different treatment options: 1 = morselized allograft and cemented cup (10 studies); 2 =morselized allograft and cementless cup (nine studies); 3 = morselized allograft and device (22 studies). The overall implant failure rate was 2.1% (95% confidence interval [CI], 1.6%-2.8%) at a mean of 9.2 years. There was no significant difference in failure rates between different treatment options (1.6% [95% CI, 0.9%-2.6%]) for morselized allograft and cemented cup; 2.1% (95% CI, 1.4%-3.2%) for morselized allograft and cementless cup; 2.5% (95% CI, 1.7%-3.7%) for morselized allograft and device) between the three different types of treatment (heterogeneity between groups p  = 0.351).It was determined that the number one cause of failure was aseptic loosening (80.5%), followed by infection (13.1%) and dislocation (6.4%). THA with reinforcement devices has a higher incidence of infection (3.6 vs. 0.7%, p  = 0.001) and dislocation (1.4 vs. 0.6%, p  = 0.010) than THA with a cemented cup., Conclusions: The use of morselized allograft in hip revision of large acetabular defects has low implant failure rates, independently of the associated type of implant. Reinforcement devices increase the risk of re-revision for infection and dislocation., Level of Evidence: Level III., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Journal of Experimental Orthopaedics published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.) more...

Nanomedicine has been extensively explored for therapeutic and diagnostic applications in recent years, owing to its numerous advantages such as controlled release, targeted delivery, and efficient protection of encapsulated agents. Integration of microneedle technologies with nanomedicine has the potential to address current limitations in nanomedicine for drug delivery including relatively low therapeutic efficacy and poor patient compliance and enable theragnostic uses. In this Review, we first summarize representative types of nanomedicine and describe their broad applications. We then outline the current challenges faced by nanomedicine, with a focus on issues related to physical barriers, biological barriers, and patient compliance. Next, we provide an overview of microneedle systems, including their definition, manufacturing strategies, drug release mechanisms, and current advantages and challenges. We also discuss the use of microneedle-mediated nanomedicine systems for therapeutic and diagnostic applications. Finally, we provide a perspective on the current status and future prospects for microneedle-mediated nanomedicine for biomedical applications., (© 2024. The Author(s).) more...

The differential signaling of multiple FGF ligands through a single fibroblast growth factor (FGF) receptor (FGFR) plays an important role in embryonic development. Here, we use quantitative biophysical tools to uncover the mechanism behind differences in FGFR1c signaling in response to FGF4, FGF8, and FGF9, a process which is relevant for limb bud outgrowth. We find that FGF8 preferentially induces FRS2 phosphorylation and extracellular matrix loss, while FGF4 and FGF9 preferentially induce FGFR1c phosphorylation and cell growth arrest. Thus, we demonstrate that FGF8 is a biased FGFR1c ligand, as compared to FGF4 and FGF9. Förster resonance energy transfer experiments reveal a correlation between biased signaling and the conformation of the FGFR1c transmembrane domain dimer. Our findings expand the mechanistic understanding of FGF signaling during development and bring the poorly understood concept of receptor tyrosine kinase ligand bias into the spotlight., Competing Interests: KK, ND, TL, TR, PD, VU, BF, PK, KH No competing interests declared, (© 2023, Karl et al.) more...

One of the greatest challenges of hip revision surgery is the need to restore extensive bone loss by creating a stable reconstruction with long-term durability. The present observational, investigator-initiated prospective study was carried out to evaluate the clinical and radiological results of the use of a commercial biomimetic collagen-hydroxyapatite composite biomaterial (RegenOss) applied in hip revision surgery. Thirty-three patients who underwent hip revision were included in this study, and 29 received up to 2 years of follow-up. The acetabulum was reconstructed using an uncemented hemispherical shell both with or without an iliac fixation stem. Functional recovery was assessed according to the Harris Hip Score (HHS) at the pre-hospitalisation check-up, and at 6-, 12-, and 24-month follow-ups. Radiological evaluation consisting of X-ray analyses (6, 12, and 24 month follow-ups) and CT scan exams (within 10 weeks post-surgery and at 12-month follow-up) were performed to evaluate the reduction in bone defect and new bone regeneration. All the patients reported a complete recovery and a considerable improvement in functional outcome assessed by the HHS, which was significantly higher at all the follow-ups than at pre-hospitalisation. Moreover, radiological assessments revealed good scaffold integration. Overall, collected data suggest that RegenOss is a valid and safe alternative to restoring acetabular bone loss in revision hip arthroplasty. more...

Umbilical cord platelet-rich plasma (C-PRP) has more growth factors and anti-inflammatory molecules compared with autologous PRP (A-PRP) derived from peripheral blood. The aim of this study was to compare intra-articular C-PRP or A-PRP injections in terms of safety and clinical efficacy for the treatment of patients with hip osteoarthritis (OA). This study investigated the results of 100 patients with hip OA treated with three weekly ultrasound-guided injections of either C-PRP or A-PRP. Clinical evaluations were performed before the treatment and after two, six, and twelve months with the HHS, WOMAC, and VAS scores. No major adverse events were recorded. Overall, the improvement was limited with both treatments. Significant improvements in VAS ( p = 0.031) and HHS ( p = 0.011) were documented at two months for C-PRP. Patients with a low OA grade (Tonnis 1-2) showed a significantly higher HHS improvement with C-PRP than A-PRP at twelve months ( p = 0.049). C-PRP injections are safe but offered only a short-term clinical improvement. The comparative analysis did not demonstrate benefits compared with A-PRP in the overall population, but the results are influenced by OA severity, with C-PRP showing more benefits when advanced OA cases were excluded. Further studies are needed to confirm the most suitable indications and potential of this biological injective approach. more...

Osteochondritis dissecans (OCD) is a chronic and painful joint condition that can occur from childhood through to adult life. Microtrauma, vascular insufficiency, or abnormal endochondral ossification are the most common causes of OCD. Reconstructive techniques for OCD of the knee are typically necessary when either non-operative or reparative/regenerative operative treatments fail, or when the OCD is irreversible. To analyze the clinical outcomes and failure rates of fresh osteochondral allograft transplantation (FOCA) used as a reconstructive strategy in OCD patients, an in-depth search was carried out on the PubMed, Scopus, and Web of Science databases concerning the existing evidence related to the use of FOCA for OCD patients in the knee joint. A total of 646 studies were found through the search and 2 studies were added after a cross-referenced examination of the articles within the bibliography. Six studies with a total of 303 OCD lesions treated with FOCA, with a mean follow-up of 6.3 years, were included. Although a limited number of low-level evidence studies on this topic are available in previous research, satisfactory clinical results and survival rates of the reconstruction are reported. However, to better define the real advantages of FOCA in the healing process of OCD lesions, comparative studies with different techniques are needed. more...

Background: A first-year interim analysis of this two-year study suggested that intra-articular injections of highly purified, natural-origin polynucleotides and hyaluronic acid (HA) as a fixed combination (PNHA) might improve knee function and joint pain more effectively than HA alone in patients with knee osteoarthritis (OA). The purpose of the second-year analysis herein described was to verify whether the first-year interim outcomes persist over the whole two-year period., Methods: Randomised, double-blind, HA-controlled clinical trial in 100 knee OA patients (98 randomised, 79 completing the study) in a high-specialisation tertiary care setting. The hypothesised difference of efficacy between PNHA and HA for the original sample size estimate is 20%. Treatment cycle: three intra-articular knee injections of either PNHA or HA, at baseline and weekly for two weeks., Evaluations: Western Ontario and McMaster Universities (WOMAC) score and Knee Society Score (KSS) as, respectively, primary and secondary endpoints, evaluated at baseline and after 2, 6, 12, and 24 months; synovial fluid levels of mediators (at baseline and the end of the treatment cycle). Adverse effects investigated at each control visit., Statistical Analysis: Kruskal-Wallis test for independent samples (nonparametric one-way analysis of variance) after correction of means for age, Body Mass Index and Kellgren-Lawrence grade. If significant, pairwise post-hoc Sidak multiple comparisons., Results: KSS total score and KSS pain item: significant improvement in both groups, with significantly more pain improvement in patients treated with PNHA (2-point reduction) than HA (1-point reduction). Both groups experienced significant long-term reductions in WOMAC total scores: significantly stronger in PNHA-treated patients after 24 months with a steady difference of 16% favouring PNHA in WOMAC pain subscore. No clinically significant adverse events in either group., Conclusions: The outcomes of the 2-year study confirmed that a short cycle of intra-articular treatment (3 weekly double-blind injections) with polynucleotides (long-acting viscosupplementation properties, chondrocyte activation, pain-relieving properties) in fixed combination with high molecular weight hyaluronic acid is more effective in improving knee function and pain in knee OA patients than HA alone. PNHA may be elective for viscosupplementation in knee OA patients with fastidious and resistant pain and worsening disease., Trial Registration: NCT02417610 . Registration, 15/04/2015. ClinicalTrials.gov database link., (© 2021. The Author(s).) more...

Every year, cancer claims millions of lives around the globe. Unfortunately, model systems that accurately mimic human oncology - a requirement for the development of more effective therapies for these patients - remain elusive. Tumor development is an organ-specific process that involves modification of existing tissue features, recruitment of other cell types, and eventual metastasis to distant organs. Recently, tissue engineered microfluidic devices have emerged as a powerful in vitro tool to model human physiology and pathology with organ-specificity. These organ-on-chip platforms consist of cells cultured in 3D hydrogels and offer precise control over geometry, biological components, and physiochemical properties. Here, we review progress towards organ-specific microfluidic models of the primary and metastatic tumor microenvironments. Despite the field's infancy, these tumor-on-chip models have enabled discoveries about cancer immunobiology and response to therapy. Future work should focus on the development of autologous or multi-organ systems and inclusion of the immune system., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: CCWH and SCG are co-founders and CCWH is the CSO of Aracari Biosciences, a company that is commercializing organ-on-chip technology through a patent licensing agreement with UCI. The terms of this arrangement are approved and monitored by the Conflict of Interest Committee at UCI (CCWH) and UC Davis (SCG). The remaining authors (NDP, VSS, YB, SPG, SG, RCF) have no declarations of interest., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.) more...

Introduction: Nonunions remain a significant burden in orthopedics, often afflicting young males of working age. Positive findings have been published using bone marrow aspirate concentrate (BMAC) and platelet-rich fibrin (PRF) for the treatment augmentation of lower limb nonunions. The aim of this study was to investigate if the treatment augmentation with BMAC and PRF can also accelerate the healing of nonunions of the upper limb., Materials and Methods: Sixty-eight patients (45 men, 23 women) affected by 75 nonunions of long bones of the upper limb were treated and divided into two groups. The first series was treated with standard surgery alone (group A); afterwards, the second series benefited from standard surgery with the addition of BMAC and PRF applied on lyophilized bone chips. Nonunions were classified radiographically according to the Weber-Cech method and prognostically using the Calori and Moghaddam scores. All patients were radiographically assessed at 1.5, 3, 6, 12, and 24 months of follow-up., Results: Baseline demographic characteristics did not present differences between groups. No differences were documented in terms of complications (two in group A and three in group B). Significant differences were instead documented in terms of healing time. The first healing signs were observed 1.5 months after surgery in 90.7% of patients in group B and 34.4% of group A (p < 0.0005). At 1.5, 3, 6, and 12 months, a higher radiographic score was found for group B (all p < 0.0005), while no difference was found at final follow-up of 24 months (90.6% of group A and 97.7% of group B achieved radiological healing). Faster healing with BMAC/PRF augmentation was confirmed for all bones, as well as for the subgroup of patients affected by atrophic nonunions (p = 0.001)., Conclusion: This study showed the benefits of restoring both mechanical and biological aspects when addressing nonunions of the long bones of the upper limb. In particular, the association of BMAC and PRF to lyophilized bone chips was safe and able to accelerate healing time. These good results were confirmed for humerus, radius, and ulna sites, as well as for challenging atrophic nonunions of the upper limb. more...

Colorectal cancer (CRC) is the third most common cancer and second leading cause of cancer-related death in the US. CRC frequently metastasizes to the liver and these patients have a particularly poor prognosis. The infiltration of immune cells into CRC tumors and liver metastases accurately predicts disease progression and patient survival. Despite the evident influence of immune cells in the CRC tumor microenvironment (TME), efforts to identify immunotherapies for CRC patients have been limited. Here, we argue that preclinical model systems that recapitulate key features of the tumor microenvironment-including tumor, stromal, and immune cells; the extracellular matrix; and the vasculature-are crucial for studies of immunity in the CRC TME and the utility of immunotherapies for CRC patients. We briefly review the discoveries, advantages, and disadvantages of current in vitro and in vivo model systems, including 2D cell culture models, 3D culture systems, murine models, and organ-on-a-chip technologies., Competing Interests: SCG is co-founder of Aracari Biosciences, a start-up company focused on the commercialization of vascularized OOC technology. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Yoon, Del Piccolo, Shirure, Peng, Kirane, Canter, Fields, George and Gholami.) more...

Introduction: Avascular necrosis of femoral head (AVN) is 1 of the main factors causing disability in young adults. Hip prosthesis can be considered an effective treatment of the painful symptoms but it is a major surgical intervention for this type of population. Thus, a large space should be left to therapeutic alternatives such as regenerative medicine.This retrospective study evaluates 52 AVN treated by core decompression, bone chips allograft, fibrin platelet-rich plasma (PRF) and concentrated autologous mesenchymal stromal cells (MSCs)., Methods: The AVN was diagnosed using magnetic resonance imaging (MRI) and graded according to ARCO classification: a patient was classified stage 1 (21 patients), stage 3 (26 patients), and 4 patients were classified as stage 4. We evaluated patients with functional scores (Harris Hip Score) and radiological analysis at 3, 6, 12 and 24 months after the procedure. Patients requiring prosthetic replacement of the joint were included; in these cases, follow-up was interrupted at the time of the joint replacement procedure., Results: Our statistical analysis showed differences between survived and failed treatments, in terms of patient profile and ARCO radiological classification.The best result occurred in patients with ARCO grades 1 and 2, while the more advanced grades showed a high failure rate. It is interesting to note that ARCO quantification, conceived as the joint surface involved in the necrosis, has a negative influence on the outcome of the procedure. Indeed, patients affected by ARCO 3a, where necrosis involved a small portion of the femoral epiphysis and the collapse of the articular surface was limited to 2 mm, showed results similar to those obtained in patients with ARCO 1 and 2., Conclusions: In conclusion, compared with the alternative technique of decompression, our data suggest that post-collapse cases with a small area of necrosis and the use of bone grafts may show better results compared to those of the literature. more...

Objective: Pain and range of motion loss are the main clinical features of osteoarthritis (OA). Hyaluronic acid (HA) is one of the infiltrative therapies for OA treatment; however, its effectiveness is a matter of an ongoing debate in clinical practice. Polynucleotides (PNs), a DNA-derived macromolecule with natural origin and trophic activity, were found to favor cell growth and collagen production, in preclinical and clinical studies regarding cartilage regeneration. This study aimed at evaluating whether injection of PNs, in combination with HA [PNs associated with HA (PNHA)], can ameliorate pain and function of knees affected by OA, more than HA alone., Design: A randomized, double-blind, controlled clinical trial., Patients: The study enrolled 100 patients, then randomized to receive PNHA or HA alone (3 weekly knee I.A. injections)., Interventions and Main Outcome Measures: Pain reduction, decrease of proinflammatory synovial fluid (SF) factors, and improvement in knee function were evaluated by Knee Society Score and WOMAC scores, after 2, 6, and 12 months and by biochemical and immunoenzymatic analyses of SF at the end of the treatment., Results: Knee Society Score total score and pain item significantly ameliorated in both groups, showing better results in PNHA- than in the HA-treated group. A significant reduction in the WOMAC score was observed over time for both groups. No significant adverse events were reported in either group., Conclusions: These findings suggest that I.A. injection of PNs, in combination with HA, is more effective in improving knee function and pain, in a joint affected by OA, compared with HA alone. more...

Adaptor proteins are a class of cytoplasmic proteins that bind to phosphorylated residues in receptor tyrosine kinases and trigger signaling cascades that control critically important cellular processes, such as cell survival, growth, differentiation, and motility. Here, we seek to characterize the interaction between epidermal growth factor receptor (EGFR) and the cytoplasmic adaptor protein growth factor receptor-bound protein 2 (Grb2) in a cellular context. To do so, we explore the utility of a highly biologically relevant model system, mammalian cells under reversible osmotic stress, and a recently introduced Förster resonance energy transfer microscopy method, fully quantified spectral imaging. We present a method that allows us to quantify the stoichiometry and the association constant of the EGFR-Grb2 binding interaction in the plasma membrane, in the presence and absence of activating ligand. The method that we introduce can have broad utility in membrane protein research, as it can be applied to different membrane protein-cytoplasmic protein pairs., (Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.) more...

The activity of receptor tyrosine kinases (RTKs) is controlled through their lateral association in the plasma membrane. RTKs are believed to form both homodimers and heterodimers, and the different dimers are believed to play unique roles in cell signaling. However, RTK heterodimers remain poorly characterized, as compared with homodimers, because of limitations in current experimental methods. Here, we develop a FRET-based methodology to assess the thermodynamics of hetero-interactions in the plasma membrane. To demonstrate the utility of the methodology, we use it to study the hetero-interactions between three fibroblast growth factor receptors-FGFR1, FGFR2, and FGFR3-in the absence of ligand. Our results show that all possible FGFR heterodimers form, suggesting that the biological roles of FGFR heterodimers may be as significant as the homodimer roles. We further investigate the effect of two pathogenic point mutations in FGFR3 (A391E and G380R) on heterodimerization. We show that each of these mutations stabilize most of the heterodimers, with the largest effects observed for FGFR3 wild-type/mutant heterodimers. We thus demonstrate that the methodology presented here can yield new knowledge about RTK interactions and can further our understanding of signal transduction across the plasma membrane., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.) more...

Background Aims: Avascular necrosis of the femoral head (AVN) occurs as common result of various conditions or develops as a primary entity, with a high freqency in young adults. Because of its tendency toward osteoarthritis requiring total hip arthroplasty, alternative treatments are being advocated, including cell therapy with mesenchymal stromal cells (MSCs). Because osteonecrotic bone is a severely hypoxic tissue, with a 1-3% oxygen tension, the survival and function of multipotent cells is questionable., Methods: In this study, the proliferative, immunophenotypic and osteogenic properties of bone marrow (BM)-derived MSCs from a clinical series of patients with AVN were evaluated under in vitro conditions mimicking the hypoxic milieu of AVN to verify the rationale for cell therapy. MSCs retrieved from the iliac crest (BM-MSC) were isolated, expanded and induced to osteogenic differentiation under a 2% pO2 atmosphere (hypoxia) in comparison with the standard 21% pO2 (normoxia) that is routinely used in cell culture assays., Results: Both proliferation and colony-forming ability were significantly enhanced in hypoxia-exposed BM-MSCs compared with BM-MSCs under normoxia. The expression of bone-related genes, including alkaline phosphatase, Type I collagen, and osteocalcin was significantly increased under hypoxia. Moreover, mineral deposition after osteogenic induction was not hampered, but in some cases even enhanced under low oxygen tension., Conclusions: These findings support autologous cell therapy as an effective treatment to stimulate bone healing in the hypoxic microenvironment of AVN., (Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.) more...

Aim: The purpose of the study was to present our arthroscopic surgical technique and the results in patient with pain after a hip replacement., Methods: Between November 2009 and September 2011, 35 patients with groin pain after total hip arthroplasty (THA) were treated arthroscopically. The patients underwent a preoperative examination consisting in careful history, physical examination, laboratory evaluation, diagnostic evaluation using x-rays and pelvis CT scans. In patients for whom the clinical picture suggested iliopsoas tendonitis, we also performed injection of local anaesthetic on the iliopsoas tendon sheath. All the patients were positioned in the supine decubitus position with traction applied, using 2 arthroscopic portals (AL, MID-A). An extensive debridement of adhesions, periprosthetic tissue and neocapsula were performed; when there were signs of iliopsoas impingement, a transcapsular tenotomy was performed according to Wettstein technique., Results: The average age was 57 (29-77) years old. The average time to onset of symptoms was 10.8 (5-15) months after THA. The average preoperative Harris Hip Score (HHS) was 44.1 (range 32-56). The average preoperative Medical Research Council (MRC) scale for muscle strenght was 3.27 (range 3-4). After 24 months of follow-up patients show an average HHS of 75.73 (range 50-91). Patients who underwent iliopsoas release show a postoperative HHS of 83.28 (range 61-91). The average postoperative MRC scale was 4.45., Conclusions: Hip arthroscopy in treatment of reactive synovitis and adhesions shows good results according to literature. Hip arthroscopy in treatment of anterior iliopsoas impingement is the most useful instrument, being less invasive than the classic open technique. more...

Background: The aim of this study was to compare return to sport activity between a short femoral cementless stem and a conventional femoral cementless stem in total hip arthroplasty in patients 50 years old and younger., Methods: We retrospectively reviewed 55 patients (61 hips) treated with a short femoral cementless stem and 28 patients (32 hips) treated with a conventional femoral cementless stem 50 years old and younger from December 2009 and December 2014.Their mean age was 39.86 (22-49) years and 38.68 (18-49) years, respectively. The mean follow-up was 54.1 (15-68) months and 52.7 (15-72) months, respectively. They were pre- and postoperatively evaluated by the clinical and radiological examination., Results: No patients with the short stem had intraoperative fracture, but 1 patient with the conventional stem had intraoperative fracture. At final follow-up, there was no statistically significant difference in Harris Hip Score, and radiographic review level between 2 stems. No hip with the short stem had thigh pain, but 6 hips with the conventional stem had thigh pain at the final follow-up. No component was revised for aseptic loosening in either group. There were no differences observed in the return to sports activity between the 2 groups., Conclusions: Our study demonstrated that both short cementless stem and conventional cementless stem provided stable fixation and achieved a satisfactory result in patients 50 years old and younger. There is no difference in return to sports activity level after the procedure. more...

Here we describe an experimental tool, termed quantitative imaging Förster resonance energy transfer (QI-FRET), that enables the quantitative characterization of membrane protein interactions. The QI-FRET methodology allows us to acquire binding curves and calculate association constants for complex membrane proteins in the native plasma membrane environment. The method utilizes FRET detection, and thus requires that the proteins of interest are labeled with florescent proteins, either FRET donors or FRET acceptors. Since plasma membranes of cells have complex topologies precluding the acquisition of two-dimensional binding curves, the FRET measurements are performed in plasma membrane derived vesicles that bud off cells as a result of chemical or osmotic stress. The results overviewed here are acquired in vesicles produced with an osmotic vesiculation buffer developed in our laboratory, which does not utilize harsh chemicals. The concentrations of the donor-labeled and the acceptor-labeled proteins are determined, along with the FRET efficiencies, in each vesicle. The experiments utilize transient transfection, such that a wide variety of concentrations is sampled. Then, data from hundreds of vesicles are combined to yield dimerization curves. Here we discuss recent findings about the dimerization of receptor tyrosine kinases (RTKs), membrane proteins that control cell growth and differentiation via lateral dimerization in the plasma membrane. We focus on the dimerization of fibroblast growth factor receptor 3 (FGFR3), a RTK that plays a critically important role in skeletal development. We study the role of different FGFR3 domains in FGFR3 dimerization in the absence of ligand, and we show that FGFR3 extracellular domains inhibit unliganded dimerization, while contacts between the juxtamembrane domains, which connect the transmembrane domains to the kinase domains, stabilize the unliganded FGFR3 dimers. Since FGFR3 has been documented to harbor many pathogenic single amino acid mutations that cause skeletal and cranial dysplasias, as well as cancer, we also study the effects of these mutations on dimerization. First, we show that the A391E mutation, linked to Crouzon syndrome with acanthosis nigricans and to bladder cancer, significantly enhances FGFR3 dimerization in the absence of ligand and thus induces aberrant receptor interactions. Second, we present results about the effect of three cysteine mutations that cause thanatophoric dysplasia, a lethal phenotype. Such cysteine mutations have been hypothesized previously to cause constitutive dimerization, but we find instead that they have a surprisingly modest effect on dimerization. Most of the studied pathogenic mutations also altered FGFR3 dimer structure, suggesting that both increases in dimerization propensities and changes in dimer structure contribute to the pathological phenotypes. The results acquired with the QI-FRET method further our understanding of the interactions between FGFR3 molecules and RTK molecules in general. Since RTK dimerization regulates RTK signaling, our findings advance our knowledge of RTK activity in health and disease. The utility of the QI-FRET method is not restricted to RTKs, and we thus hope that in the future the QI-FRET method will be applied to other classes of membrane proteins, such as channels and G protein-coupled receptors. more...

Thanatophoric dysplasia type I (TDI) is a lethal human skeletal growth disorder with a prevalence of 1 in 20,000 to 1 in 50,000 births. TDI is known to arise because of five different mutations, all involving the substitution of an amino acid with a cysteine in fibroblast growth factor receptor 3 (FGFR3). Cysteine mutations in receptor tyrosine kinases (RTKs) have been previously proposed to induce constitutive dimerization in the absence of ligand, leading to receptor overactivation. However, their effect on RTK dimer stability has never been measured experimentally. In this study, we characterize the effect of three TDI mutations, Arg248Cys, Ser249Cys, and Tyr373Cys, on FGFR3 dimerization in mammalian membranes, in the absence of ligand. We demonstrate that the mutations lead to surprisingly modest dimer stabilization and to structural perturbations of the dimers, challenging the current understanding of the molecular interactions that underlie TDI., (Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.) more...

Here, we study the homodimerization of the transmembrane domain of Neu, as well as an oncogenic mutant (V664E), in vesicles derived from the plasma membrane of mammalian cells. For the characterization, we use a Förster resonance energy transfer (FRET)-based method termed Quantitative Imaging-FRET (QI-FRET), which yields the donor and acceptor concentrations in addition to the FRET efficiencies in individual plasma membrane-derived vesicles. Our results demonstrate that both the wild-type and the mutant are 100% dimeric, suggesting that the Neu TM helix dimerizes more efficiently than other RTK TM domains in mammalian membranes. Furthermore, the data suggest that the V664E mutation causes a very small, but statistically significant change in dimer structure. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova., (Copyright © 2014 Elsevier B.V. All rights reserved.) more...

Plasma membrane derived vesicles are used as a model system for the biochemical and biophysical investigations of membrane proteins and membrane organization. The most widely used vesiculation procedure relies on formaldehyde and dithiothreitol (DTT), but these active chemicals may introduce artifacts in the experimental results. Here we describe a procedure to vesiculate Chinese hamster ovary (CHO) cells, widely used for the expression of recombinant proteins, using a hypertonic vesiculation buffer containing chloride salts and no formaldehyde or DTT. We characterize the size distribution of the produced vesicles. We also show that these vesicles can be used for the biophysical characterization of interactions between membrane proteins. more...

Purpose: A male patient suffering from non-union of the femoral diaphysis after a traumatic fracture was treated with deep decortication and grafted with lyophilized bone, platelet gel (PG) and autologous bone marrow stromal cells (BMSCs). After 40 days from surgery, he was re-operated, due to fracture secondary displacement, caused by inappropriate load during sports activity. In addition to radiographs, two bone biopsies were retrieved: this allowed for a histological evaluation of the early response of host bone to the graft. To our knowledge, there is no report describing such early tissue response., Methods: A clinical-radiographic evaluation of the patient and a histomorphometric analysis of the bone biopsies were performed., Results: An early reparative bone formation was observed adjacent to the osteointegrated graft. Non-resorbed bone chips and large islands of non-vital bone particles, surrounded by fibrous tissue, were observed in a zone of sclerotic diaphyseal bone, that is the process was delayed despite decortication., Conclusions: These findings support the concept, until now evidenced only by imaging, that bone chips added with PG and BMSCs are effective in shortening the healing time in fracture non-union. The clinical relevance of deep decortication and vascularization is emphasized., Level of Evidence: Therapeutic studies-investigating the results of treatment, Level V. more...

We retrospectively evaluated the postoperative results of total hip arthroplasty (THA) in patients presenting with Crowe group IV dislocated hips. Overall, results were compared with regard to the type of osteotomy performed (Z or oblique) to define the correct indications for surgical technique and choice of prosthetic implant. Thirty-three subtrochanteric shortening and derotational osteotomies in primary THA were performed in 26 patients secondary to congenital hip dislocation. A Z osteotomy was performed in 14 cases and an oblique osteotomy in 19. The surgical approach was direct lateral, and surgery was aimed at restoring the anatomic hip center. Femoral and acetabular fixation was uncemented. The most used stem was the S-ROM (DePuy, Leeds, United Kingdom), and the couplings used were ceramic-ceramic (7 cases), ceramic-polyethylene (3 cases), metal-polyethylene (15 cases), and metal-metal (3 cases). Mean follow-up was 88±45 months. According to the Merle D'Aubigné score, the overall clinical results were good in 23 cases, satisfactory in 6, and fair in 4. Union of the osteotomy occurred in 97% of cases, and the mean time required for osteotomy union was 6±2 months without significant differences between Z and oblique osteotomies. At last follow-up, there was loosening of 1 cup and 1 stem, and revision was necessary. Twelve percent of patients experienced postoperative dislocation and 9% developed neuropraxia of the femoral nerve. The clinical and radiological results were similar in both groups, with a high rate of pain relief, an improvement in limb-length discrepancy, and reduced limping, leading to a smaller or no insole. Currently, the more complex Z osteotomy has been abandoned, because a modular stem prosthesis with metaphyseal sleeve allows the oblique osteotomy to be used with an easier and shorter surgical procedure., (Copyright 2011, SLACK Incorporated.) more...

We reviewed performed a retrospective review of our series of excision arthroplasty patients and identified 16 patients who had undergone the procedure for sepsis, and who we had subsequently subjected to revision to a total hip arthroplasty (THA). Mean follow-up was 96 +/- 15 months. There was a significant reduction in limb length discrepancy and a marked improvement in walking capability. Range of movement improved most in patients under 65 years of age. Patient selection is critical, because THA after excision arthroplasty is complex, and may have less satisfactory results primary surgery. more...

In this prospective, randomized, double-blind study, the effect of Pulsed Electromagnetic Fields (PEMFs) was investigated in 30 subjects undergoing hip revision using the Wagner SL stem. The subjects were treated for 6 h/day up to 90 days after revision. Study end points were assessed clinically by the functional scale of Merle D'Aubigné and instrumentally by Dual-Energy X-ray Absorptiometry (DXA) at the Gruen zones. Subject improvement according to Merle D'Aubigné scale was higher (P < 0.05) in subjects undergoing active stimulation compared to placebo. In analyzing the DXA findings, we subtracted for each area the postoperative bone mineral density (BMD) values from those measured at 90 days and we considered all results above 3.5% as responders. There were no significant differences in the average BMD values at each Gruen zone between the two groups both postoperatively and at 90 days investigation. In Gruen zones 5 and 6, corresponding to the medial cortex, we observed six responders (40%) in both areas in the control group, while in the stimulated group we observed 14 (93%) and 10 (66%) responders, respectively (both P < 0.05). This study showed that PEMF treatment aids clinical recovery and bone stock restoration. more...