INTRODUCTION

Recently the evolution of prosthesis technology allows the surgeon to replace entire limbs. These special prostheses or megaprostheses were born for the treatment of severe oncological bone loss. Recently, however, the indications and applications of these devices are expanding to other orthopaedic and trauma situations. Since some years we are implanting megaprostheses in non-oncological conditions such as septic post-traumatic failures represented by complex non-unions and critical size bone defects.

The purpose of this study is to retrospectively evaluate the clinical outcome of this treatment and register all the complications and infection recurrence.

Multiple myeloma (MM) is an incurable hematological tumor stemming from malignant plasma cells. MM cells accumulate in the bone marrow (BM) and shape the BM niche by establishing complex interactions with normal BM cells, boosting osteoclasts (OCLs) differentiation and causing bone disease. This unbalance in bone resorption promotes tumor survival and the development of drug resistance.

The communication between tumor cells and stromal cells may be mediated by: 1) direct cell-cell contact; 2) secretion of soluble factors, i.e. chemokines and growth factors; 3) release of extracellular vesicles/exosomes (EVs) which are able to deliver mRNAs, miRNAs, proteins and metabolites in different body district.

Primary CD138+ MM cells were isolated from patients BM aspirates. MM cell lines were cultured alone in complete RPMI-1640 medium or co-cultured with murine (NIH3T3) or human (HS5) BMSC cell lines or murine Raw264.7 monocytes in DMEM medium supplemented with 10% V/V FBS. Silencing of Jagged1 and Jagged2 was obtained by transient expression of specific siRNAs or by lentiviral transduction using a Dox-inducible system (pTRIPZ). EVs were isolated using differential ultracentrifugation. EVs concentration and size were analyzed using Nano Track Analysis (NTA) system. The uptake of PKH26-labelled MM-derived EVs by HS5 or Raw264.7 was measured after 48 hours by confocal microscopy and flow cytometry. Osteoclast (OCL) differentiation of Raw264.7 cells was induced by 50ng/ml mRANKL, co-culturing with MM cells, CM or EVs. OCLs were stained by TRAP Kit and counted. Bone resorption was assessed by Osteo Assay Surface plates. Flow cytometric detection of apoptotic cells was performed after staining with Annexin V. Gene expression was analyzed by qRT-PCR, while protein levels were determined using flow cytometry ELISA or WB.

Notch oncogenic signaling is dysregulated in several hematological and solid malignancies. Notch receptors and ligands are key players in the crosstalk between tumor cells and BM cells. We have demonstrated that: 1) the dysregulated Jagged ligands on MM cells trigger the activation of Notch receptors in the nearby stromal cells by cell-cell contact. This results in the release of anti-apoptotic and growth stimulating factors, i.e. IL6 and SDF1; 2) MM cells promote the development of bone lesions boosting osteoclast differentiation by secreting soluble factors (i.e. RANKL) and by the activation of Notch signaling mediated by direct contact with osteoclast precursors; 3) Finally, we present evidences that EVs play a crucial role in the dysregulated interactions of MM cells with the microenvironment and that Notch signaling regulates their release and participate in this cross-talk.

These evidences supports the hypothesis that Jagged targeting on MM cells may interrupt the communication between tumor cells and the surrounding milieu, blocking the activation of the oncogenic Notch pathway and finally resulting in the a reduction of MM-associated bone disease and drug resistance.

Introduction

Various anti-infective agents can be added to the surface of orthopaedic implants to actively kill bacteria and prevent infection. Silver (Ag) is a commonly used agent in various anti-infective applications. Silver disrupts bacterial membranes and binds to bacterial DNA and to the sulfhydryl groups of metabolic enzymes in the bacterial electron transport chain, thus inactivating bacterial replication and key metabolic processes. Recently we are implanting Silver coated megaprosthesis for the treatment of post-traumatic septic non unions/bone defects and for infected hip or knee prosthesis revision. We treat these complications utilizing a two steps procedure: 1° step: devices removal, resection, debridment and antibiotic spacer implantation; 2° step: spacer removal and megaprosthesis implantation. This technique produce a reactive pseudosynovial membrane, well known in traumatology (Masquelet technique), following the Chamber Induction Technique principles. This chamber creates the perfect environment in which implant the prosthesis with safety. We are nowadays investigating if this membrane could optimize the Silver antimicrobical effects reducing the Silver ions dispersion and reducing toxicity on the human body.

Introduction

Throughout the world the number of large joint arthroprosthetic implants continues to increase and consequently the number of septic complications with prosthesis mobilizations, periprostehtic bone loss or non-unions. The implant of large resection prosthesis (megaprosthesis) in selected patients could be a good solution both in hip and knee infected prosthesis with bone defects.

The two stage techniques with a first operation to debride, prosthesis components removal and antibiotic spacer implantation followed by a subsequent final prosthetic implant offer great results even in highly complex patients.

Introduction

In orthopaedics one of the most common complications is infection. The occurrence of a postoperative infection significantly increases the failure rate; both in the case of prosthetic and trauma surgery. Some patients despite a meticulous antiseptic procedures, a close monitoring of controls peri- and post-operative undergo the development of infection of the fixation devices with the risk of developing osteomyelitis. This risk is highly increased in the distal leg because of the known problems with blood supply and poor muscle coverage. The functionality of the affected segment is impaired, quoad fuctionem, with increased risk of amputation and sometimes with poor prognosis, quoad vitam. The therapeutic strategy proposed by our group is to treat an osteomyelitic site as a pseudo-tumor with a megaimplant following a ladder strategy driven by the NUSS classification. This work shows our experience with a developing system by Waldemar-LINK highlighting critical issues and preliminary results.

INTRODUCTION

The hip arthroplasty implant is currently growing up both in orthopedic and trauma practice. This increases the frequency of prosthesis revision due to implant loosening often associated with periprosthetic osteolysis that determine the failure and lead to a loss of bone substance. Nowadays there are numerous biotechnologies seeking to join or substitute the autologous or omologous bone use. These biotechnologies (mesenchymal stromal cells, growth factors and bone substitutes) may be used in such situations, however, the literature doesn't offer class 1 clinical evidences in this field of application.

Introduction

Our department is responsible specifically for complex cases resulting from trauma. Our experience does not want to add what has been clearly demonstrated by multicenter studies on the efficacy of rivaroxaban but aims to demonstrate how the use of this molecule was effective also in mega-prosthesis and how it has proven to be flexible and safe in dealing with difficulties and surgical complications more common in such difficult cases.

Introduction

The development of new megaprosthesis for the treatment of large bone defects has offered important opportunities to orthopedic oncologic surgeons for the replacement of skeletal segments such as the long bones of the upper and lower limbs and the relative joints. Our experience, treating non union and severe bone loss, has brought us, sometimes, to be confronted with the reality of some failures after unsuccessful attempts to reconstruct. Faced with certain radiological and / or clinical drastic situations we wanted to apply the principles of Biological Chamber and oncologic surgery with megaprosthetic replacement solutions. We implanted megaprosthesis with either 1 step or 2 steps (previous antibiotated spacer) technique depending on the septic patient conditions. The aim of this study is to retrospectively evaluate both clinical and radiological outcomes in patients underwented to a lower limb megaprosthesis implant and complications were recorded.

INTRODUCTION

The hip arthroplasty implant is currently growing up both in orthopedic and trauma practice. This increases the frequency of prosthesis revision due to implant loosening often associated with periprosthetic osteolysis that determine the failure and lead to a loss of bone substance.

Nowadays there are numerous biotechnologies seeking to join or substitute the autologous or omologous bone use. These biotechnologies (mesenchymal stromal cells, growth factors and bone substitutes) may be used in such situations, however, the literature doesn't offer class 1 clinical evidences in this field of application.

Introduction:

The development of new prostheses due to large resections has offered important opportunities to orthopedic surgeons mainly in oncology. A medline research can easily underline how poor is the international experience about this cases in nonunion: 75 results for megaprosthesis just 7 works in nonunion.

It is proposed the experience of our department, which deals specifically with the treatment of nonunion, in cases of repeated failures to treatment.

One of the most significant problems in the treatment of relapsing nonunion is the consequent worsening of joint function.

Critical bone defects, sepsis, joint fractures and unclear relapsing nonunions are the most common cases for a megaprosthesis treatment.

In these cases, even if it obtains the healing of nonunion the functional result would be presumptively poor. This radiological or clinical situation drove us, in such cases, to drastic solutions following the principles of cancer cases.

We implanted megaprosthesis with either techniques: 1 stage or 2 stages depending on the clinical findings. In nonunion the main decision making was the septic or aseptic status.