Impending atypical femoral fractures associated with bisphosphonates: postoperative diagnosis after hip prosthesis. Clinical cases presentation.

BACKGROUND AND AIM: Number of hip prosthesis implants in arthritis, number of patients treated with bisphosphonates to prevent fragility fractures and, together, number of atypical femoral fracture's cases are increasing. CASE SERIES: This article describes two cases of hip arthritis, treated with hip replacement, in patients using bisphosphonates for a long time; in both cases an incomplete atypical femoral fracture was misdiagnosed before the surgery. Authors describe the importance to carry out a complete osteometabolic and radiographic pre-operative examination of patients in treatment with bisphosphonates going to hip replacement, to check the possible presence of incomplete atypical femoral fracture and to optimize surgical and pharmacological treatment. CONCLUSIONS: In hip prosthesis surgery, prior diagnosis of incomplete atypical femoral fractures can indicate the choice of a different kind of prosthesis stem to optimize surgical results. This can also positively impact to rehabilitation in term of duration and daily activities recovery.

Intraoperative Load Sensing in Total Knee Arthroplasty Leads to a Functional but Not Clinical Difference: A Comparative, Gait Analysis Evaluation.

INTRODUCTION: Although Total Knee Arthroplasty (TKA) is a successful procedure, a significant number of patients are still unsatisfied, reporting instability at the mid-flexion range (Mid-Flexion Instability-MFI). To avoid this complication, many innovations, including load sensors (LS), have been introduced. The intraoperative use of LS may facilitate the balance of the knee during the entire range of motion to avoid MFI postoperatively. The objective of this study was to perform a Gait Analysis (GA) evaluation of a series of patients who underwent primary TKA using a single LS technology. METHODS: The authors matched and compared two groups of patients treated with the same posterior stabilized TKA design. In Group A, 10 knees were intraoperatively balanced with LS technology, while 10 knees (Group B) underwent standard TKA. The correct TKA alignment was preoperatively determined aiming for a mechanical alignment. Clinical evaluation was performed according to the WOMAC, Knee Society Score (KSS) and Forgotten Joint Score, while functional evaluation was performed using a state-of-the-art GA platform. RESULTS: We reported excellent clinical results in both groups without any statistical difference in patient reported outcome measurements (PROMs); from a functional standpoint, several GA space-time parameters were closer to normal in the sensor group when compared to the standard group, but a statistically significant difference was not reached. CONCLUSIONS: Gait Analysis represents a valid method to evaluate TKA kinematics. This study, with its limitations, showed that pressure sensitive technology represents a valid aid for surgeons aiming to improve the postoperative stability of TKA; however, other factors (i.e., level of intra-articular constraint and alignment) may play a major role in reproducing the normal knee biomechanics.

Robotic-Assisted Unicompartmental Knee Arthroplasty Reduces Components' Positioning Differences among High- and Low-Volume Surgeons.

Robotic-assisted medial unicompartmental knee arthroplasty (mUKA) has been introduced to improve accuracy in implant positioning and limb alignment, overcoming the reported high failure rates of conventional UKA. Indeed, mUKA is a technically challenging procedure strongly related to surgeons' skills and expertise. The purpose of this study was to evaluate the likelihood of robotic-assisted surgery in reducing the variability of coronal and sagittal component positioning between high- and low-volume surgeons. We evaluated a prospective cohort of 161 robotic mUKA implanted between May 2018 and December 2019 at two high-volume robotic centers. Patients were divided into two groups: patients operated by "high-volume" (group A) or "low-volume" (group B) surgeons. We recorded intraoperative lower-limb alignment, component positioning, and surgical timing. Postoperatively, every patient underwent a radiographical protocol to assess coronal and sagittal femoral/tibial component alignment. Range of motion and other clinical outcomes were assessed pre- and 12 months postoperatively by using oxford knee score, forgotten joint score, and visual analog scale. Of 161 recruited knees, 149 (A: 101; B: 48) were available for radiographic analysis at 1 month, and clinical evaluation at 12 months. No clinical difference neither difference in mechanical alignment nor coronal/sagittal component positioning were found (p > 0.05). A significant difference was recorded in surgical timing (A: 57 minutes; B: 86 minutes; p < 0.05). No superficial or deep infections or other major complications have been developed during the follow-up. Robotics surgery in mUKA confirmed its value in improving the reproducibility of such technical procedure, with satisfactory clinical outcomes. Moreover, it almost eliminates any possible differences in component positioning, and lower limb alignment among low-and high- volume knee surgeons.

Use of a Plasma-Sprayed Titanium-Hydroxyapatite Femoral Stem in Hip Arthroplasty in Patients Older than 70 Years. Is Cementless Fixation a Reliable Option in the Elderly?

BACKGROUND: Although cementless implants are increasing in popularity, the use of cementless femoral stems for total hip arthroplasty (THA) and hip hemiarthroplasty (HH) in elderly patients remains controversial. The aim of this study was to report the outcomes of a cementless stem used in a large multicentric cohort of elderly patients receiving elective THA and HH for displaced femoral neck fracture. METHODS: A total of 293 patients (301 hips) aged 70 years or older (mean age, 78 years; range, 70-93) who received the same cementless plasma-sprayed porous titanium-hydroxyapatite stem were retrospectively evaluated after primary THA and HH to investigate stem survival, complications, and clinical and radiographic results. RESULTS: Cumulative stem survival was 98.5% (95% CI, 96.4-99.4%; 91 hips at risks) with revision due to any reason as the end-point at 10-year follow-up (mean 8.6 years, range 4-12). No stem was revised due to aseptic loosening. The mean Forgotten Joint Score was 98.7. Radiographically, the implants showed complete osseointegration, with slight stress-shieling signs in less than 10% of the hips. CONCLUSION: The use of cementless stems was proven to be a reliable and versatile option even in elderly patients for elective THA and HH for femoral neck fracture.

The New Challenge in the Management of Proximal Femur Fractures during SARS Cov-2 outbreak.

The aim of this study is to evaluate how the spread of Sars-Cov-2 has changed the epidemiology of proximal femur fractures in two major trauma centers in Italy, understanding the workload and the best allocation of the resources for the orthopedics department in such an emergency situation. The rate of patients from January 2019 to April 2020 hospitalized with femoral neck fractures (group A) and trochanteric fractures (group B) were recorded. Demographic data, timing of surgical treatment and the length of stay were recorded. Data show that the number of proximal femur fractures has remained unchanged in the COVID and pre-COVID era (ranging from an average of 91.14/month in the pre-COVID era to 76/month in March and 80/month in April). In our trauma centers, the rate of patients operated on within 48 hours has remained stable (78.19% vs 77.92%), while the length of stay has decreased during the COVID period (8.9 days vs 6.5 days in March and 6.8 days in April). Proximal femur fractures, even during the COVID period, are a constant issue and a new challenge for the healthcare system. The main goals of management are to preserve patients from viral infection, to provide early surgical treatment and fast track protocol for discharge.

Bibliometric trend analysis in a decade of European Orthopaedic literature.

Purpose The purpose of this bibliometric study was to summarize European orthopedic literature produced by EFORT memberships between 2009 and 2019 and to identify the 100 most cited articles, analyzing the characteristics that made them so interesting for the orthopedic scientific world. Method A search of the literature was conducted using Clarivate Analytics Web of Science in the subject category "orthopaedics"; then the results were summarized using Web of Science tools. Results A total of 160.375 articles were found: most of these were produced by England. In particular the most prolific institution was the University of London. Analyzing in detail the 100 most cited publications emerged that most of them were review published in journal with high impact factor (Q1). The University of Oxford was the institution with the greatest number of contributions (13%). The most cited topics were osteoarthritis (24%), followed by orthopedic basic science (22%). Biomaterials was the most common topic by ordering the 100 analyzed articles according to "usage count", a recent indicator of the level of interest in a specific item. Conclusion This bibliometric study can be useful to identify topics of interest for future scientific research and to outline the features that make some publications more interesting than others.

Mesangiogenic Progenitor Cells Are Tissue Specific and Cannot Be Isolated From Adipose Tissue or Umbilical Cord Blood.

Mesangiogenic progenitor cells (MPCs) have been isolated from human bone marrow (BM) mononuclear cells. They attracted particular attention for the ability to differentiate into exponentially growing mesenchymal stromal cells while retaining endothelial differentiative potential. MPC power to couple mesengenesis and angiogenesis highlights their tissue regenerative potential and clinical value, with particular reference to musculoskeletal tissues regeneration. BM and adipose tissue represent the most promising adult multipotent cell sources for bone and cartilage repair, although discussion is still open on their respective profitability. Culture determinants, as well as tissues of origin, appeared to strongly affect the regenerative potential of cell preparations, making reliable methods for cell isolation and growth a prerequisite to obtain cell-based medicinal products. Our group had established a definite consistent protocol for MPC culture, and here, we present data showing MPCs to be tissue specific.

Synthetic Bone Grafting in Aseptic Loosening of Acetabular Cup: Good Clinical and Radiological Outcomes in Contained Bone Defects at Medium-Term Follow Up.

Restoring bone loss is one of the major challenges when facing hip revision surgery. To eliminate the risk of disease transmission and antigenicity of allografts and donor-morbidity of autografts, the use of synthetic bioceramics has become popular in the last decade. Our study investigated the effectiveness of impaction bone grafting (IBG) of contained acetabular defects (Paprosky 2 and 3a) using a porous ceramic-based hydroxyapatite bone substitute (Engipore, provided by Finceramica Faenza S.p.A., Faenza, Italy) mixed with a low percentage of autologous bone (obtained from reaming when available). We retrospectively assessed 36 patients who underwent acetabular revision using IBG using a porous ceramic-based hydroxyapatite bone substitute with cementless implants with a mean follow-up of 4.4 years. We evaluated, at regular intervals, patients clinically (using the Hip Harris Score and Oxford Score) and radiologically to evaluate the rate of incorporation of the graft, the presence of radiolucent lines or migrations of the cup. Clinical scores significantly improved (WOMAC improved from 49.7-67.30, and the HSS from 56-89). The rate of implants' survival was 100% at our medium follow-up (4.4 years). We reported five cases of minor migration of the cup, and radiolucent lines were visible in seven patients at the last-follow up. The graft was well-incorporated in all patients. The results presented in this study suggest the HA bone substitute is an effective and safe bone graft when facing hip revision surgery; thus, longer follow-up studies are required.

Evaluation of Microbial Adhesion and Biofilm Formation on Nano-Structured and Nano-Coated Ortho-Prosthetic Materials by a Dynamic Model.

The bio-engineering technologies of medical devices through nano-structuring and coating was recently proposed to improve biocompatibility and to reduce microbial adhesion in the prevention of implantable device-related infections. Our aim was to evaluate the ability of new nano-structured and coated materials to prevent the adhesion and biofilm formation, according to the American Standard Test Method ASTM-E2647-13. The materials composition was determined by X-ray Fluorescence and Laser Induced Breakdown Spectroscopy. Silver release was evaluated by Inductively Coupled Plasma Mass Spectrometry analysis. The gene expression levels of the Quorum Sensing Las and Rhl system were evaluated by the ΔΔCt method. The Log bacterial density (Log CFU/cm2) on TiAl6V4 was 4.41 ± 0.76 and 4.63 ± 1.01 on TiAl6V4-AgNPs compared to 2.57 ± 0.70 on CoCr and 2.73 ± 0.61 on CoCr-AgNPs (P < 0.0001, A.N.O.V.A.- one way test). The silver release was found to be equal to 17.8 ± 0.2 µg/L after the batch phase and 1.3 ± 0.1 µg/L during continuous flow. The rhlR gene resulted in a 2.70-fold increased expression in biofilm growth on the silver nanoparticles (AgNPs) coating. In conclusion, CoCr showed a greater ability to reduce microbial adhesion, independently of the AgNPs coating. The silver release resulted in promoting the up-regulation of the Rhl system. Further investigation should be conducted to optimize the effectiveness of the coating.

Which role for synthetic ligaments in the reconstruction of patellar tendon chronic rupture after TKA? Mid-term outcomes using LARS ligament.

BACKGROUND AND AIM OF THE WORK: Patellar tendon rupture is a rare complication after Total Knee Arthroplasty (TKA) which often requires surgical treatment. Patients with chronic lesions or tendon degenerations showed good results when treated using autografts or allografts, but these techniques showed poor outcomes at long-term follow-up (FU). Moreover, allografts have high costs and limited availability, not to mention the increased risk of immune reactions and infections. Recently, the use of synthetic ligaments for patellar tendon reconstruction has taken hold with encouraging results. We report our experience in the treatment of patellar tendon ruptures after TKA using the Ligament Advanced Reinforcement System-LARS®. METHODS: Clinical evaluation was performed using the Knee Society Score and recording extensor lag. Instrumental evaluation was performed using ultrasound imaging to assess patellar tendon thickness and using conventional x-rays to assess prosthesis' mobilization signs and patella's height. RESULTS: At the final FU, 6 knees were included in our study. Patient's mean age was 66.7. Patellar tendon reconstruction occurred after a mean time of 4 months from the previous surgery. The mean FU was 44,2 months. The mean Knee Score was 63.3 and the mean Function Score was 35. In 4 knees the extensor lag was < 10° while in 2 knees it was > 20°. The mean ISI was 1.16, while the average increment in tendon thickness was 127.12%. CONCLUSIONS: In our opinion, synthetic ligaments can be successfully employed for the reconstruction of patellar tendon breakage after TKA and rTKA in selected patients, in order to quickly return them to their activity of daily living.

Septic femoral shaft non-union treated by one-step surgery using a custom-made intramedullary antibiotic cement-coated carbon nail: case report and focus on surgical technique.

Background and aim of the work: In the orthopaedic and traumatological fields septic non-unions represent a severe complication, hard to manage and treat. Traditionally, the surgical technique consists in to two sequential steps: debridement with administration of local and systemic antibiotics associated with temporary stabilization of the fracture and subsequent reconstruction of bone and soft tissues. Recently, the use of some devices to treat septic non-union by one-step surgery have been introduced with encouraging resultsMethods: We reported our experience with a case treated by one-step procedure using a custom-made intramedullary antibiotic cement-coated carbon nail. We reviewed the literature and described the surgical technique employed in this case. Results: At 6 months from surgery the patient was able to perform full weight-bearing and carry out the normal activities of daily living. Serum inflammatory markers normalized and radiographic controls showed the presence of a mechanically good bone callus at the non-union site. The bone resection carried out determined a limb length discrepancy of 3 cm, that was corrected through a temporary shoe lift, currently well tolerated. The patient regained full ROM of the right knee. Conclusion: Intramedullary antibiotic cement-coated nail associated with systemic antibiotic therapy proved to be an effective treatment to control the infection and provide immediate stability at the septic non-union/fracture site, allowing a rapid functional recovery. It represents a valid option especially in patients who refuse external devices or surgical additional procedures, as in our case. (www.actabiomedica.it).

Bone integration in acetabular revision hip arthroplasty using equine-derived bone grafts: a retrospective study.

PURPOSE: During the last decade, total hip arthroplasty has become a common procedure performed in young patients, as well as elderly ones. This has led to an increase in total hip arthroplasty revisions. Loosening of primary components with associated bone loss represents the major cause of total hip arthroplasty revision. This study evaluates the safety and performance of an enzyme-deantigenic equine-derived bone graft material in acetabular defect reconstruction. METHODS: Records of 55 patients who were treated for Paprosky type II or III acetabular bone defects with arthroplasty revisions using equine-derived bone and followed for an average of 34 months (range from 24 to 48 months) were analyzed. RESULTS: Of the 55 revisions, 49 (89%) were regarded as successful, showing good osteointegration without signs of mobilization. Failures included six cases (11%) of mobilization: five cases of aseptic mobilization (9.1% of revisions, 83% of failures) and one case of septic mobilization (1.9% of revisions, 17% of failures). These results are consistent with those of studies having a similar follow-up period for allografts used in combination with trabecular metal components. CONCLUSIONS: Results of the present study suggest that enzyme-treated equine-derived bone grafts may be a valid alternative to autogenous and homologous bone grafts in total hip arthroplasty revision.

How to Build a Patient-Specific Hybrid Simulator for Orthopaedic Open Surgery: Benefits and Limits of Mixed-Reality Using the Microsoft HoloLens.

Orthopaedic simulators are popular in innovative surgical training programs, where trainees gain procedural experience in a safe and controlled environment. Recent studies suggest that an ideal simulator should combine haptic, visual, and audio technology to create an immersive training environment. This article explores the potentialities of mixed-reality using the HoloLens to develop a hybrid training system for orthopaedic open surgery. Hip arthroplasty, one of the most common orthopaedic procedures, was chosen as a benchmark to evaluate the proposed system. Patient-specific anatomical 3D models were extracted from a patient computed tomography to implement the virtual content and to fabricate the physical components of the simulator. Rapid prototyping was used to create synthetic bones. The Vuforia SDK was utilized to register virtual and physical contents. The Unity3D game engine was employed to develop the software allowing interactions with the virtual content using head movements, gestures, and voice commands. Quantitative tests were performed to estimate the accuracy of the system by evaluating the perceived position of augmented reality targets. Mean and maximum errors matched the requirements of the target application. Qualitative tests were carried out to evaluate workload and usability of the HoloLens for our orthopaedic simulator, considering visual and audio perception and interaction and ergonomics issues. The perceived overall workload was low, and the self-assessed performance was considered satisfactory. Visual and audio perception and gesture and voice interactions obtained a positive feedback. Postural discomfort and visual fatigue obtained a nonnegative evaluation for a simulation session of 40 minutes. These results encourage using mixed-reality to implement a hybrid simulator for orthopaedic open surgery. An optimal design of the simulation tasks and equipment setup is required to minimize the user discomfort. Future works will include Face Validity, Content Validity, and Construct Validity to complete the assessment of the hip arthroplasty simulator.

Giovanni Alfonso Borelli: The Precursor of Medial Pivot Concept in Knee Biomechanics.

A new philosophy of science and medicine had spread throughout the 17th-century Italy: the "Scientific Revolution." Giovanni Alfonso Borelli (1608-1679) was one of the most charismatic and brilliant scientists of his generation in Europe. He extended to biology the rigorous analytic methods developed by his indirect mentor Galileo in the field of mechanics. In his masterpiece " De Motu Animalium ," Borelli analyzed structure, motion, balance, and forces concerning almost all the principal joints of the human body, in static and dynamic situations. In particular, he accurately studied the anatomy and biomechanics of the knee joint. He sustained that femoral condyles shift backward during flexion, allowing a wider range of movement. Furthermore, he observed that, when the knee flexes, the lateral condyle moves backward more than the medial condyle: this concept is nowadays known as medial pivoting. The aim of this article is to describe the life and work of this important Italian scientist and to present his unrecognized contribution to modern knee biomechanics.

The 50 most cited articles about wrist surgery.

The purpose was to establish a ranking of the 50 most cited articles about wrist surgery and analyse their features. Science Citation Index Expanded was used to identify the 50 most frequently cited orthopaedic journal articles written in English, searching for the topic "wrist surgery" in the subject category ''Orthopaedics''. Then, we analysed the number of citations, citation density, authorship, article institution, the year of publication, the country of origin of the article, name and impact factor of the journal, and publication type of the article. The 50 most cited articles were published in only 6 of the 74 journals included under the category "orthopaedics". Citation count ranged from 256 for the first one to 67 for the 50th article. Most of them were written by American authors. These articles were published between 1991 and 2011. "Distal Radius Fractures" was the most common issue. This type of bibliographic analysis could be particularly useful for other young Authors who would like to improve their research in wrist and hand surgery and make their publications more citable and appreciated by the scientific community.

Clinical and instrumental evaluation of two different regimens of tranexamic acid in total hip arthroplasty: a single-centre, prospective, randomized study with 80 patients.

PURPOSE: The use of tranexamic acid (TXA) in total hip arthroplasty (THA) can significantly reduce blood losses with many clinical and economical advantages. However, no consensus has been reached regarding the optimal regimen for TXA administration. The aim of this study is to analyse and compare the haemostatic effect of two different intravenous (IV) regimens of TXA. MATERIALS AND METHODS: We planned a single-centre, prospective, randomized study including 80 patients who underwent primary unilateral minimally invasive THA because of a hip osteoarthritic degeneration. We divided patients into two groups: the G10 group received two IV doses of 10 mg/kg of TXA, and the G20 group received two doses of 20 mg/kg. RESULTS: No significant differences in mean minimum levels of Hb and HcT stratified by days after surgery were uncovered between the two groups despite the use of two different dosages of TXA. Also the mean blood volume loss was statistically similar between two groups. No differences were also observed regarding the occurrence of adverse effects. CONCLUSIONS: In two IV bolus regimens of TXA administration, the use of a dose of 10 or 20 mg/kg provides statistically similar results in blood loss sparing. Therefore, the use of two 10 mg/kg doses could be considered more advisable in order to reduce the potential thromboembolic risks related to this drug.

Profunda Femoris Artery Pseudoaneurysm after Intramedullary Fixation for a Pertrochanteric Hip Fracture.

INTRODUCTION: Vascular complications after femoral fixation are rare and not only easy to recognize but also potentially life-threatening. The aim of this case report is to describe how a pseudoaneurysm of the deep femoral artery can complicate an intramedullary nailing after a pertrochanteric fracture and how it can be treated. CASE REPORT: We report the case of a 90-year-old female who developed a pseudoaneurysm of the profunda femoris artery 16 days after intramedullary femoral nailing for a pertrochanteric hip fracture. Stenting of the artery was urgently performed with a consequent resolution of the symptoms. CONCLUSION: Diagnosis of vascular complications after hip surgery may be very challenging because symptoms are often nonspecific. Despite their rarity, it is important to know this type of complications to address the diagnostic pathway in the right direction and to treat them promptly.

Evaluation of the Effects of the Metha® Short Stem on Periprosthetic Bone Remodelling in Total Hip Arthroplasties: Results at 48 Months.

INTRODUCTION: Total hip arthroplasty is one of the most performed procedures in orthopaedic surgery. Implantation of a prosthesis determines changes in the distribution of loads on the host bone, and this phenomenon, known as stress shielding, is related to the biomechanical characteristics of the implant. Usually stress shielding involves the proximal portion of the femur by reducing the mechanical strength and ability to withstand the transmitted loads. The aim of our study is to demonstrate how the use of a short hip stem reduces the stress shielding phenomenon to the proximal femur. MATERIALS AND METHODS: The study analyzed 20 patients undergoing hip prosthesis surgery with a short stem (Metha<, B. Braun Medical, Inc., Bethlehem, Pennsylvania) at the Ist Orthopaedic Division of Pisa University (between December 2008 and January 2010). Each patient was subjected to analysis of periprosthetic bone mineral density by a bone densitometry (dual emission X-ray absorptiometry [DEXA] with the metal removal software) at 0, 6, 12, 18, 24, and 36 months, following a protocol based on the evaluation of the changes of bone density in the seven Gruen zones. RESULTS: We recorded minimal changes in bone mineral density (BMD) at the level of the greater trochanter (-1.44%) and at the level of the calcar (-3.7%). BMD increased significantly after four years at the level of the lateral distal regions (R2 +9.6% - R3 + 12.4%) and at the level of the distal medial regions (R5 + 8.2% - R6 + 13.1%). We compared the results obtained with the literature data at 12 and 24 months with the same stem (Metha<). At 12 months follow up, we did not see a significant difference between our data and the data published in the literature. However, after 48 months of follow-up, we recorded significant differences in the curves of periprosthetic bone reabsorption at the level of the greater trochanter (Zone 1) and at the level of the calcar (Zone 7). DISCUSSION: The data obtained from our study are in agreement with other studies in the literature, which demonstrates how the use of short stems preserves the metaphyseal bone stock at the level of the proximal femur, reducing the stress shielding phenomenon. From our data, obtained at 24 months and confirmed at 36, stress shielding seems to minimally occur at the level of the calcar. At the level of the great trochanter, we saw a good load distribution that maintained the baseline BMD; these data are in opposition to the literature data that showed a high increase of BMD at the level of the calcar (+12.9%) and a decrease at the level of the great trochanter. From the analysis of the radiographic images of our cases, and of the cases published with the same stem, these differences in load transfer encountered between the great trochanter and the calcar seems to be related to the level of the femoral neck osteotomy and the consequent stem position (varus/valgus). CONCLUSION: We conclude that the amount of periprostetic bone reabsorption around the Metha< stem seems to be strictly related to the surgical technique and the final implant position.

Nanoparticles for Tendon Healing and Regeneration: Literature Review.

Tendon injuries are commonly met in the emergency department. Unfortunately, tendon tissue has limited regeneration potential and usually the consequent formation of scar tissue causes inferior mechanical properties. Nanoparticles could be used in different way to improve tendon healing and regeneration, ranging from scaffolds manufacturing (increasing the strength and endurance or anti-adhesions, anti-microbial, and anti-inflammatory properties) to gene therapy. This paper aims to summarize the most relevant studies showing the potential application of nanoparticles for tendon tissue regeneration.

Hydroxyapatite in total hip arthroplasty. Our experience with a plasma spray porous titanium alloy/hydroxyapatite double-coated cementless stem.

PURPOSE: Total hip arthroplasty could fail due to many factors and one of the most common is the aseptic loosening. In order to achieve an effective osseointegration and reduce risk of lossening, the use of cemented implant, contact porous bearing surface and organic coating were developed. Aim of this study was to evaluate clinical and radiological mid-term outcomes of a porous titanium alloy/hydroxyapatite double coating manufactured cementless femoral stem applied with "plasma spray" technique and to demonstrate the possibility to use this stem in different types of femoral canals. METHODS: Between January 2008 and December 2012, 240 consecutive primary total hip arthroplasties (THAs) were performed using a porous titanium alloy/hydroxyapatite double coating manufactured cementless femoral stem. 182 patients were examined: 136 were females (74.7%) and 46 males (25.2%); average age was 72 years old (ranging from 26 to 92 years old). For each patient, Harris Hip Scores (HHS) and Womac Scores were collected. All X-ray images were analyzed in order to demonstrate stem survival rate and subsidence. RESULTS: Harris Hip Score was good or excellent in 85% of the cases (average 90%) and mean WOMAC score was 97.5 (ranging from 73.4 to 100). No cases of early/late infection or periprosthetic fracture were noticed, with an excellent implant survival rate (100%) in a mean period of 40 months (ranging from 24 and 84 months). 5 cases presented acute implant dislocation, 2 due to wrong cup positioning in a dysplastic acetabulum and 3 after ground level fall. Dorr classification of femoral geometry was uses and the results were: 51 type A bone, 53 type B bone and 78 type C bone. Stem subsidence over 2 mm was considered as a risk factor of future implant loosening and was evidenced in 3 female patients with type C of Dorr classification. No radiolucencies signs around the proximally coated portion of stem or proximal reabsorption were visible during the radiographic follow-up. CONCLUSIONS: Concerning the use of porous titanium alloy/hydroxyapatite double coating, this study reported an excellent implant survival rate in a mid-term period with a rate of 1,64% of subsidence in patients with type C of femoral canal but with an optimal HHS and Womac Score results. Regarding this stem, primary stability is guaranteed by trapezoid shape of proximal region and tapering in frontal plane through press-fit technique. Radiological absence of pedestal has been accepted as sign of no excessive stress transmission to distal cortex due to its tapered diaphyseal region. Thanks to the reported data, Authors can consider this double coating a valid choice with an excellent medium-term survival and encouraging subsidence results. Further studies are needed to ensure these results can be replicated.