INTRODUCTION

Since July 2008 we are experimenting a new cup with iliac screw fixation, developed on the idea of Ring and Mc Minn. Iliac fixation is permitted by a polar screw of large diameter, coated by HA, which allows a compression to bone and a firm primary stability. Moreover it's possible to increase primary stability with further smaller peripherals screws. We present this new cup and report the preliminary results.

Ceramic-on-ceramic bearing is an attractive alternative to metal-on-polyethylene bearing due to the unique tri-bological advantages of alumina. However, despite the long-term satisfactory results obtained so far in the vast majority of patients, failure may occur in a few cases.

Clinical, radiographic, laboratory and microbiological data of 30 consecutive subjects with failed alumina-on-alumina total hip arthroplasties (THA) were analyzed to define if foreign body reaction to wear debris may be responsible for periprosthetic bone resorption, as in conventional metal-to-polyethylene bearings. In all cases, clinical and radiographical material was reviewed, retrieved implants were examined, and histology of periprosthetic tissues was analyzed. Massive osteolysis was never observed. Apart from 5 five patients for which revision surgery was necessary due to the occurrence of late infection, in all other cases failure had occurred due to secondary implant instability (as in the case of screwed sockets, 19 cases) or to malpositioning of the implant (5 cases). One patient suffered from chronic dislocation.

In the vast majority of cases, ceramic wear debris was absent or scarce, and did not induce any tissue reaction. In a few cases with severe wear, debris was evident in clusters of perivascular macrophages, notably in the absence of foreign body multinucleated cells, confirming the excellent biocompatibility of ceramics.

These findings indicate that wear debris and peri-prostetic bone resorption were the effect rather than the cause of failure, differently from revised metal-on-polyethylene bearings, in which foreign body cell reaction is the main pathogenetic mechanism of failure. On the contrary, mechanical problems, due to incorrect surgical technique or to inadequate prosthetic design, may cause instability of the implant, in turn resulting in wear debris production and moderate if any biological reaction.

The use of monoblock tapered stems has shown very good results in hip revision surgery, particularly in case of severe proximal femur bone deficiency.

However a too valgus neck, a short offset, may result in a high risk of dislocation. In addiction monoblock stems make the control of limb length difficult, and potentially increase the risk of subsidence or intraoperative fracture. Different types of modular tapered stems with distal fixation have been developed to allow a more user-friendly restoration of limb-lenght discrepancy and an indipendent proximal control of offset and anti-retroversion.

We assessed 64 hip revisions performed on 63 patients (mean age 62 years). Indication for treatment was: aseptic loosening (42 cases) septic loosening (18 cases) and periprosthetic fracture (4 cases). According to Paprosky classification, femoral defects were staged as type I (2 cases), type II (20 cases), type IIIA (25 cases) and type IIIB (13 cases); periprosthetic fractures were all type B2 according to the Vancouver classification. In all cases we used a Restoration® Modular (Striker, Orthopaedics) cone-conical uncemented stem implanted by a lateral approach, with a trans-femoral osteotomy in 19 cases. A preventive cerclage cable was used in 10 patients in case of very thin cortex. We used the minimum size stem in most of the cases.

Mean follow-up was 20 months (range 6–36). Short-term complications included hip dislocation (1 case), recurrent infection (1 case), stem subsidence > 5 mm (1 case). Mean Harris Hip Score improved from 43 to 81.9 (t test p< 0.0005), while limb lenght discrepancy improved in 97% of cases with symmetry in 76%.

The use of modular revision stems is an effective alternative in hip revision surgery that ensures good primary stability, while modularity enables the implant to be tailored to the patient, allowing restoration of the limb length and correct muscular balancing.

Aims: Surface modification of biomaterials to be used as scaffolds in tissue engineering is a promising method to improve device multi-functionality and biological properties. Biomimetic surface treatments, such as changes in nano-structure and attachment of biomolecular signals, enhance material bioactivity and affinity for specific cells. In this study the functionalization of a titanium surface with vitronectin-derived nonapeptide(HVP) and RGD peptides was investigated. Bone forming cells were used to analyse the role of each surface modification in the initial steps of cell adhesion process and then proliferation and differentiation.

Method: Smooth titanium samples were functionalized by different chemical treatments in order to obtain varying amount of peptide adhesion. Human marrow stro-mal cells (MSC) were seeded and cultured in osteogenic medium. Cell adhesion and morphology were assessed by fluorescence microscopy after 6 hours. Viability of MSC was quantified at 7 and 14 days from plating, proliferation was measured using DNA and total protein content, and osteoblast phenotype expression was assayed using alkaline phosphatase (ALP) and calcium content.

Results: The results showed that presence of HVP and RGD peptides improves cell morphology in early adhesion on surface, compared to control (titanium without peptides). Activity of ALP and Ca²⁺ content of (1:1000)HVP and RGD samples were higher than the other experimental surfaces with or without peptides, even if they did not reach the values of control cells on tissue culture polystyrene.

Discussion: Properties acquired with chemical treatments can improve titanium surfaces. These data provide information useful to develop biomimetic cell-friendly surfaces for bone engineering.

Aims: It is well known that the success of an orthopedic implant is determined by a close apposition between bone and implant surface. The excellent physical properties and the controlled degradation of poly-ε-caprolactone (PCL) has been shown, however the suitability for bone engineering applications of a material is critically influenced by the interactions between cells and scaffold. The aim of this study was to evaluate the interaction between bone marrow cells and PCL surface. Bone marrow cells were obtained from femurs of New Zealand rabbits and seeded on PCL directly (WBMC) or after gradient centrifugation (MSC), mimicking the in vivo colonization of PCL after implantation and the pre-seeding strategy.

Methods: PCL was dissolved in chloroform (3% w/v solution) and spin coated as a thin (100nm) film onto p-doped silicon wafers. The surface wettability and roughness were analyzed by SFE measurements and AFM. Cells were seeded on PCL and adhesion/proliferation evaluated at 1, 7, 14, 21 and 28 days. Fluorescence microscopy and SEM imaging were performed at defined time endpoints.

Results: At 2 wks adherence-selected MSC had already formed confluent multilayers, whereas WBMC were still semi-confluent. At 4 wks a consistent layer of ECM was observed underneath the cell layers of both cultures.

Conclusions: PCL is a proper substrate for bone cell attachment and growth, as cell confluence was reached at 2 wks for MSC and at 3–4 wks for WBMC. To avoid any risk of bacterial contamination, the seeding of WBMC on PCL scaffold, which implies reduced handling of cells outside the body, was shown to be effective and may be recommended in the clinical practice.

Replacing a fused or ankylosed hip with a prosthesis has several advantages. It reduces the pain in the lumbar-sacral spine and the ipsilateral knee. It gives a better range of movement and leg length is restored.

In this study we present our experience of 50 cases of total hip arthroplasty in fused or ankylosed hips. Aetio-pathogenesis was rhizomelic spondylitis in 35 cases, sequelae of cox it is in 2, posttraumatic in 4, Ankylosis in 6, and fusion in 3. For clinical assessment we used the Merle D’Aubignè score, and for radiographic evaluation we used the Gruen method of area subdivision

Of the 50 prosthesis implanted, 3 were removed due to aseptic loosening. The other were the radiographically stable after an average follow-up of 12 years. Preoperative clinical scores were: pain (2.9), range of motion (2.5), and walking (2.1). At the latest exam the scores were: pain (5.5), motion (4.6), walking (4.5). Preoperative leg shortening was 3.5 cm, whereas at the latest exam it was 0.9 cm. Lumbalgia decreased notably in 62%.

Total hip arthroplasty may have advantages over fusion on one hand, but on the other it is technically more difficult and gives results that are inferior to common indications. It is therefore important to assess patients (time of fusion, age of patient, residual muscular function) preoperatively to obtain good results.

The Gpsystem Medacta vision system is composed of an infrared camera that produces and receives infrared rays reflected by almost 3 reflectors mounted on different rigid body devices (F=femoral, T=tibial, G=guide), in order to determine its position with an error lower than 0.35mm. Data received from this vision system are than elaborated by the Cinetique Gpsystem Version 1.0 system in order to determine the correct cutting guide positioning both for the femur and the tibia. The cutting guide is moved on different planes by 5 electric engines applied on 5 no ending screws.

The first step of this system is determining, with the F and the T rigid bodies, patient’s lower limb kinematic in order to evaluate its mechanical axis, its flexion-extension range of movement and its pathological deviations. The second step is evaluating anatomical landmarks to find out the correct degrees of tibial and femoral cuts: these landmarks are the medial and lateral tibial glena, the distal femoral condyles, the posterior femoral condyles, the anterior femoral cortex, the tibial tuberosity, the Whiteside line and the epycondilar axis (each anatomical landmark is identified by multiple points in order to decrease possible errors). The third step is applying the cutting guide and the Grigid body on the femoral clamp in order to estimate the correct level for the tibial cut than, once the tibial osteotomy is done the vision system controls its correct execution and the soft tissue balancing of the knee. The fourth step is calculating with the Gpsystem the correct orientation of the femoral cutting guide and checking its positioning and cutting execution. The last step is applying the test-prosthesis verifying the mechanical axis of the knee and than assembling the definitive prosthesis.

Since now we have applied 10 Cinetique knee prosthesis with the Medacta computer navigation system with good results and good positioning of the prosthesis

Medacta computer navigation system for Cinetique knee arthroplasty is innovative for its simple cutting guide and movement device both in their hardware than in their way of using and for a simpler software interface; these characteristics allows faster surgeon technique learning, shortening of surgical time and a better prosthesis positioning.

Girdlestone’s arthroplasty is often used to treat septic loosening of hip prostheses. Although this operation provides goodresults with regards to pain and loosening, it causes instability and in the hip and limb shortening that force the patient to use walking aids.

From 1990 to 1999 we treated ten cases of revisionhip arthroplasty after Girdlestone’s arthroplasty. Girdleston e’sarthroplasty was carried out in all cases due to sepsis in the previousimplant. Preoperatively all patients underwent granulocyte-labeledscintigraphy. For clinical evaluation we used the Merle D’Aubignè score.

From 1990 to 1999 we treated ten cases of revisionhip arthroplasty after Girdlestone’s arthroplasty. Girdleston e’sarthroplasty was carried out in all cases due to sepsis in the previousimplant. Preoperatively all patients underwent granulocyte-labeledscintigraphy. For clinical evaluation we used the Merle D’Aubignè score.

Girdlestone’s arthroplasty is very effective for treating septic loosening of hip prostheses, but it causes severe walking impediment. Revision surgery restores limb length and walking. Patients that undergo this treatment should be checked for residual sepsis, which may jeopardize the operation. Currently we are experimenting with spacers with antibiotics and our initial results are promising.

Compromised patellar bone stock poses significant the chnical problems in primary and revision knee arthroplasty. In these situations, traditional approaches have included: non resurfacing, patellectomy, patellar bone grafting, ‘Gull-Wing’ osteotomy. A new material (Trabecular Metal) fabricated using a tantalum metal and vapor deposition techhnique that create a metallic strut configuration with 80%porosity, and physical and mechanical properties similar to bone has been introduced. The authors studied the short-term results following patellar resurfacing using trabecular metal patella in primary and revision total knee arhroplasty (TKA).

Nine patients undergoing primary (2 cases) or revision (7 cases) TKA with the use of a trabecular metal patella were evaluated at a mean of 16 months follow-up. All patients had marked patellar bone deficiency precluding resurfacing with a standard cemented patellar button. The all polyethylene patela was cemented into the trabecular metal base and the remaining patella bone stock; additional fixation was provided by # 2 non absorbable sutures through the peripheral holes on the metal shell.

Revision TKA may be complicated by severe patellar bone loss that preclude implantantion of a standard cemented patellar component. Several options including patellectomy, non resurfacing and osteotomy or grafting of remaining bony shell have been proposed. It is rare in primary knee arthroplasty that the patella has been so eroded that resurfacing is not feasible. Trabecular metall patella may be indicate in the complex revision or even primary knee arthroplasty in which all that remains of the patella is a thin shell of anterior cortical. The short-term results of patellar resurfacing with trabecular metal have demonstrated favorable results.

The vast majority of total-joint-replacement components utilized are modular to some degree. Modularity increases the surgeon’s options in both primary and revision THA. Modular prostheses allow the surgeon intra-operative versatility, allowing adjustment of leg length, offset, neck length, and version. This is particularly helpful in CHD, posttraumatic arthritis and in hip revision. Modularity may be applied also to the neck, enlarging the range of choice for difficult cases. Howeverusing of a modular interface increases risk of fretting, wear debris, and dissociation and mismatching of components.

A series of 87 revision THA performed between 1997 and 2003 using modular neck was reviewed. The pros-theses are AnCA-Fit with a cementless titanium anatomical stem and Profemur with a tapered revision titanium stem. Both provided with a modular neck inserted by morse taper and a hemispheric press-fitted cup. All the implants have a ceramic-ceramic coupling. Four cases were performed due to recurrent dislocation and 83 for implant loosening. Retrieved necks were studied searching for corrosion.

No cases of disassembly or fracture of the neck were observed. Two cases of dislocation were treated with brace. Analysis of retrieved necks confirmed the absence of corrosion. Leg length discrepancy decreased from 57.7% to 22%. One post-operative infection was successfully treated with debridment.

Modular neck system allows to correct intraoperatively leg length and offset, choosing between five interchangeable necks available in two lengths: straight, varus-valgus, ante-retroverted. Restoration of hip biomechanics prevents instability. Removal of the neck allows a better surgical exposure when femoral stem is retained. Moreover it allows to maintain ceramic-ceramic coupling. Modular prosthesis has some problems related to risk of corrosion, fretting, fracture or dislocation of components. We observed no cases of disassembly of components or fracture and comparative analysis between retrieved necks and those experimentally studied confirmed absence of corrosion.

The uncemented cup with iliac stem ensures immediate primary stability by fixation to the hipbone in acetabular loosening with severe bone defect. Homologous bone grafts contribute to restoring bone stock, which is a fundamental requirement for long lasting implant stability.

From 2002 to 2004 we implanted 23 cups with iliac stems in 22 patients. In 7 cases there was also stem loosening, and so total hip arthroplasty was performed. In 2 patients the defect was grade 2b, in 5 grade 3a, and in 16 grade 3b according to Paprosky. A direct lateral approach was performed in the supine position. Morselized bone grafts were used in all cases by the “impaction grafting” technique, and in 4 cases modelled structural grafts were also employed. Mean follow-up has been 18 months (8–32).

So far we have not had any cases of loosening. At follow-up x-rays showed remodelling of the grafts with integration.

The cup with iliac stem enables primary stability on healthy bone tissue, and protects the grafts form mechanical stimulation, thus allowing them to integrate and restore bone-stock. It also restores the centre of rotation, and provides functional benefits and implant stability.

The authors studied the short-term results following patellar resurfacing using trabecular metal patella. Ten patients underwent primary (2 cases) or revision (8 cases) TKA with the use of a trabecular metal patella and were evaluated at a mean follow-up of 24 months. All patients had marked patellar bone deficiency or patellar absence precluding resurfacing with a standard cemented patellar button. The all polyethylene patella was cemented into the trabecular metal base and the remaining patella bone stock; additional fixation was provided by non-adsorbable sutures through the peripheral holes on the metal shell. No intraoperative complications occurred. There was no displacement of any trabecular metal patellar component and no patellar fractures. The fixation appeared excellent at three to six months radiographic evaluation with uniform bone contact in the peripheral regions in both lateral an Merchant radiographic views. The mean Knee Society scores improved in all patients.

Aim: To assess the effect of lyophilised bone grafts, autologous platelet gel and autologous medullary cells on bone repair processes after tibial osteotomy for genu varum

Methods: Thirty patients, divided into 3 groups by the generation of random sampling numbers, were treated by valgus osteotomy for genu varum with a minimum correction of 8 mm and fixation using a titanium plate (TITAN plate® Citieffe).

The groups were thus divided:

Group 1: lyophilised bone chips.

Group 2: lyophilised bone chips + platelet gel

Group 3: lyophilised bone chips + platelet gel + packed autologous medullary cells (Buffy coat).

At six weeks X-rays, MRI and needle biopsies were carried out. The tissue underwent morphological and microstructural tests.

Results confirmed that the use of platelet gel and packed medullary cells as adjuvant for the lyophilised bone aid bone repair and graft integration. Morphological and morphometric tests showed that at six week the newly formed bone of group 3 had better mechanical properties.

Conclusions: This study shows that the use of platelet gel and packed autologous medullary cells combined with lyophilised bone chips produces a faster and mechanically stronger recovery of bone stock in the treatment of bone defects.

Introduction Total hip arthroplasty in patients affected by major dysplasia poses great surgical difficulties due to insufficient primary acetabulum, small femoral canal, excessive anteversion of the femoral neck, traction on the neurovascular structures, muscular imbalance that is difficult to restore, and marked epiphyseal rising. In this study we present our experience in lowering and arthroplasty in major hip dysplasia, obtained by shortening osteotomy achieved in a single stage, using techniques designed to diminish possible risks.

Materials and methods From 1989 to 2000 we treated 20 patients (27 operations, 7 bilateral) at our institute who were affected by the sequela (lowering of the prosthesis) of Eftekhar Grade-C (11 cases) or Grade-D (16 cases) congenital luxation of the hip. Mean follow-up was 63 months. Clinical results were assessed before and after surgery according to the Merle D’Aubigné method. We also evaluated the presence and degree of Trendelenburg position and the possible use of shoe lifts. The radiographic results of the hip prosthesis were assessed by the Gruen and Dee Lee methods for the stem and cup respectively.

Results The mean preoperative clinical score according to the Merle D’Aubigné classification was 3 ± 1 for pain, 3 ± 1 for walking, and 4 ± 2 for movement. The preoperative Trendelemburg position was very marked in all patients. In 18 cases out of 27 a shoe lift was used with a mean height of 60 mm ± 10. We performed a “Z” osteotomy in 14 cases and an oblique osteotomy in 13 cases. The postoperative mean clinical score was 6 ± 1 for pain, 6 ± 1 for walking, and 5 ± 1 for movement. Postoperative Trendelemburg position was present in 19 cases, and 9 cases out of 27 still used a shoe lift with a mean height of 30 mm ± 10. Movement of the cup and stem was observed at 84 months and 112 months’ follow-up respectively, which required revision surgery.

Conclusions The choice between oblique and Z osteotomy depends on two parameters: the surgeon’s experience and the extent of femoral resection. Z osteotomy may be more difficult to perform technically, but it enables better adaptation of the prosthesis to the femoral segments for resections over 35 mm. No significant differences in time to unite were observed between oblique and Z osteotomies.

Aim Although converting a loosened fixation of the proximal femur into a total hip arthroplasty restores the joint, it is a technically complex operation and often requires steps that are not usually performed in arthroplasty for common diseases. The aim of this study was to assess clinical and radiographic results of 127 total hip arthroplasties due to loosening of proximal femur fixation, performed at our institute.

Materials and methods From 1987 to 2001 we performed 127 total hip arthroplasties (THA) in patients with loosened facture fixation of the proximal femur. Patients treated by endoprosthesis were excluded from this study.

The patients were divided into two groups according to the fracture site. Group 1 included 71 patients with medial fracture, and Group 2 contained 56 patients pertrochanteric or subtrochanteric fracture. All patients were assessed by the Merle d’Aubignè clinical evaluation method. Radiographically, the bone-implant interface was assessed by the presence of radiolucency lines according to the DeLee-Charnley method modified by Martell

Results The mean time lapse between fixation and conversion was 31 months for Group 1 and 10 months for Group 2 patients. In 12 cases of Group 2 bone grafts were used and surgery time was on average 20′ longer than that of Group 1. Furthermore, in Group 2, we had 4 dislocations compared to none in Group 1. In Group 2 long-stem prostheses with diaphyseal conical anchorage were more frequently used, whereas in Group 1 standard prostheses were used in all cases. Patients of Group 2 had a lower clinical score for the three parameters assessed (pain, walking and ROM) than those of Group 1. The final clinical results were also better for Group 1 patients.

Conclusions This study shows how THA in fixation loosening of proximal femur fractures can provide good results. Especially in patients with medial fractures of the femur, since the anatomy is not altered, THA does not pose any particular difficulties and ensures excellent results. In fractures of the trochanteric mass, where non-union or malunion alter markedly the anatomy of the bone segment, the site for the implant, results are certainly inferior However, careful planning of the operation, the use of special prostheses, and bone grafts enable satisfactory results to be achieved in these patients too.

Introduction: morcelized defatted bone-Bank graft (MOD-B) has been employed in 249 patients for different diseases in Rizzoli Institute from 1998 to 2002. 82 hip revisions, 51 spine fusions, 50 osteolitic bone cavities, 47 non-unions). Good results obtained with MOD-B have been the reason for different researches of his properties like an antibiotic carrier and, in the same time, a particular new bone graft.

Material and Methods:

MOD-B with antibiotic powder and PMMA Cylinders (A-MB-C) have been placed in saline solution and plasma for 4 weeks, compared with cylinders made with PMMA and antibiotic.

Results:

The MOD-B + antibiotic + PMMA have released the higher quantity of antibiotic for all the 4 weeks.

Conclusions: morcelized defatted bone-Bank graft is an important opportunity to restore bone loss lesions but, with a septic situation, it is not so easy obtain good results. A very important goal would be to have a graft with good antibiotic deliver system, good mechanical compressive strength and the potential capacity to become new living bone.

Valgus knee is a complex deformity, characterised by varying degrees of flexion, external rotation and valgus deviation. Contracture of external ligamentous structures makes correction and soft tissue balance often difficult and may lead to persistent post-operative instability. Further problems include patellar tracking, bone defects, especially at the external femoral condyle, and the risk of external popliteal sciatic (EPS) nerve palsy after surgery. Krackow distinguished three types of valgus knee: type 1 with integral medial peripheral structures; type 2 with severe medial structure laxity and impossibility to correct passively; and type 3 which is the sequela of over-correction tibial osteotomy.

From 1996 to 2003 we performed 64 fusions due to valgus knee in 41 females and 23 males, aged between 55 and 76 years (mean 67.5). Of these, 52 deformities were type 1, nine type 2, and three type 3. For type-1 lesions we always used prostheses with posterior stabilisation (PS), and balanced the capsulo-ligamentous structures. In type-2 lesions we used a vincolo condilare prosthesis with CCK in two cases and a cerniera prosthesis in two cases, whereas in the remaining five cases we used a PS prosthesis. In type-2 deformities we used a PS prosthesis with a modular tibial component with metal augments. Mean follow up was 45 months.

Radiographically, valgus deformity fell from 22.4° (10° min – 35° max) to 5.4° (3° min – 9° max). Post-operative results, according to the HSS score, were excellent in 51 cases, fair in 11 cases, and poor in two cases, due to the need to perform revision in two stages in an infected prosthesis 6 months after surgery in one case, and aseptic loosening in another.

Valgus knee due to arthritis can be successfully treated by total knee arthroplasty using various techniques, according to the clinical severity. EPS nerve palsy has been cited as a potential problem in total knee arthroplasty. We did not observe this complication in our series, probably because we maintain the knee in continuous slight flexion for the first 18–24 h.

Patellar tracking is the most common complication observed following total knee arthroplasty. It may constitute a minor disorder or even frank dislocation. Its main cause is a rotation defect in the prosthetic components. CT is the most reliable instrumental test to assess this rotation defect, and an excellent aid for planning a possible revision operation.

From January 1999 to November 2003 we treated 33 patients with a total of 35 painful knees using TC prostheses. Ten patients were male and 33 female. Mean age was 66 years. We performed CT scanning using a modified Berger technique. The lower limbs were extended and scans were performed perpendicular to the mechanical axis of the knee from the supracondylar region of the femur to the plane passing under the distal end of the tibial component up to the anterior tibial tuberosity. Reference lines to assess the rotation of each prosthetic component were drawn electronically on the scan planes.

Adding together the rotation values of the prosthetic components, we observed that when total internal rotation was between 10° and 4°, there was subluxation or frank dislocation. When total internal rotation was between 1° and 4° the disorder was not severe, such as patellar tilt. When total internal rotation was less than 1° or when the components were externally rotated, no femorotibial compartment disorders were observed. The modified Berger technique enabled us to correlate the degree of prosthetic internal rotation with the severity of the disorder and further demonstrate the benefits of femoral component external rotation on patellar glide and ligament balance of the prosthesis.

The authors believe that using CT with the helicoidal technique, by modifying Berger’s technique, enables an accurate assessment of prosthetic component rotation, subsequent correlation with femoro-patella symptoms, and adequate pre-operative planning in case of revision surgery.

Aim: to assess the effect of lyophilized bone grafts, autologous platelet gel and autologous medullary cells on bone repair processes after tibial osteotomy for genu varum.

Methods: thirty patients, divided into 3 groups by the generation of random sampling numbers, were treated by valgus osteotomy for genu varum with a minimum correction of 8 mm and fixation using a titanium plate (TITAN plateA8 Citieffe).

The groups were thus divided:

Group 1: lyophilized bone chips.

At six weeks X-rays, MRI and needle biopsies were carried out. The tissue underwent morphological and microstructural tests.

Results: preliminary results confirmed that the use of platelet gel and packed medullary cells as adjuvant for the lyophilized bone aid bone repair and graft integration. Morphological and morphometric tests showed that at six week the newly formed bone of group 3 had better mechanical properties.

Conclusions: this study shows that the use of platelet gel and packed autologous medullary cells combined with lyophilized bone chips produces a faster and mechanically stronger recovery of bone stock in the treatment of bone defects.

Total joint arthroplasty is the most significant advance in the treatment of end-stage arthritic disease of major joints. Despite the clinical success of this surgical procedure, however, some total joint prostheses fail, and although a failed prosthesis can be replaced, the results of revision arthroplasty are not as good as the first time. Studying the failed prosthesis and the associated bone and soft tissues provides insight into the causes of failure.

Most prosthetic failures are the result of structural limitations of the implant components. Although material failure may be sudden, a much more common cause is gradual aseptic loosening of the prostheses. Aseptic loosening is caused by both mechanical (gradual loss of material by wear) and biological (osteoclastic resorption of adjacent bone) factors. Wear particles induce a foreign body reaction characterized by a pseudomembrane composed of granulomatous tissues including macrophages, fibroblasts, giant cells, and osteoclasts in addition to debris particles. The extent of this response is driven by the number, size, composition, surface area, and types of particles present. Although there are differences in the relative local toxicity of each of these particles, the end result is the same. These mechanical and biological factors are unavoidable, and the success of a total joint prosthesis depends on the rate with which they occur. Polyethylene wear particles (1–200 ?) are the primary cause of loosening. They are strongly birefringent under polarized light microscopy. Smaller particles are phagocytized by histiocytes, whereas larger particles are surrounded by foreign body giant cells. Fragmentation of PMMA may also cause particulate debris. The presence of these particles (30–100 ?) may be deduced by empty spaces into the soft tissues, often bordered by foreign body giant cells, since PMMA is dissolved by xylene during routine histological techniques. Metal oxides form on the surface of chrome-cobalt or titanium alloys due to an electrolytic process, and stresses on the surface of the metal shear the oxides into the surrounding tissues, causing a black pigmentation of the tissues. Histologically, the black deposits of oxidized metals are seen extracellularly as well as in the cytoplasm of histiocytes. In addition to oxidation, metal undergoes corrosion and, as a result, metal ions enter the soft tissues and the bloodstream. A ceramic-on-ceramic coupling generates a significantly lower amount of debris as compared to the conventional metal-on polyethylene solution. When present, ceramic debris cause a mild histiocytic reaction without giant cells and virtually no osteoclastic bone resorption. There are various secretory proteins at the interfacial membrane that can affect bone turnover, including the cytokines IL-1, IL-6, Il-10, and TNF-a. Other factors involved with bone resorption include the enzymes responsible for catabolism of the organic component of bone, such as MMPs. Prostaglandins, in particular PGE2, are also known to be important intercellular messengers in the osteolytic cascade. More recently, several mediators known to be involved in stimulation or inhibition of osteoclast differentiation and maturation, such as RANKL and osteoprotegerin, have been suggested as key factors in the development and progression of osteolysis.

Infection around a prosthesis also causes loosening in approximately 1–5% of cases. Total joint prostheses become infected by two mechanisms, wound contamination at the time of surgery by Staph. aureus or Staph.epidermidis, and late hematogenous spread of organisms (Staphylo- and Streptococci, E. Coli, Pseudomonas, and anaerobes). The following factors facilitate bacterial growth. First, reaming and sawing, as well as PMMA polymerization, cause necrosis of necrotize bone adjacent to the implant, and such nonvascularized area permits bacteria to grow, safe from circulating host defenses. Second, a highly hydrated matrix of extracellular polymeric substances (biofilm) is formed that defends bacteria from antibiotics and phagocytosis. Third, some metals, such as nickel or cobalt, may depress macrophage function. The distinguishing histologic features of an infected prosthesis is an acute inflammatory reaction: a finding of > 5 PMN or of > 50 lymphocytes/hp field are presumptive for infection. Because some low-grade infections fail to stimulate an acute inflammatory reaction, they go undiagnosed until postoperative period when microbacterial culture results are available. To date, no single routinely used clinical or laboratory test has been shown to achieve ideal sensitivity and specificity for the diagnosis of prosthetic joint infection, and in most cases the diagnosis depends on a combination of clinical features, radiographic findings, and laboratory results. Intra-operative tissue cultures may be falsely negative because of prior antimicrobial exposure, a low number of organisms, inappropriate culture media, or atypical organisms. Conversely, cultures may be falsely positive because of contamination in the operating room, during transport, or in the laboratory. If the implant is removed, the entire prosthesis can be cultured. Moreover, because prosthetic joint infection is a biofilm-mediated infection, techniques that sample bacteria in biofilm, such as sonication or enzymatic treatment, may improve the diagnosis of prosthetic joint infection. More recently, molecular techniques are being used to detect nucleic acid in samples from infected patients even when conventional techniques are negative because of unusual microbial growth requirements or failure to grow after antimicrobial exposure or due to unfavourable environmental conditions. A disadvantage of such approach is its extreme sensitivity, leading to the possibility of false positive results.

The clinical presentation of prosthetic joint infection may be indistinguishable from that of aseptic implant failure. In many cases, culture of granulomatous tissue around failed prostheses, preoperatively diagnosed as aseptically loosened, reveals the presence of bacteria that may per se significantly contribute to the recruitment, maturation and activation of osteoclasts and that superimpose to the foreign body reaction to wear debris. The presence of a smouldering infection in case of “aseptic” failure observed in revision arthroplasties. A systematic investigation on all retrieved implants is mandatory to define the precise role of each potential factor contributing to the pathogenesis of failure, in order to further improve the quality of care of patients having total joint arthroplasty.