The use of neck modular adapter is a relative new solution for hip revision arthroplasty. This device assure a lot of advantages for the orthopaedic surgeon because Bioball can be use in different situations in order to solve different complications: hip prosthesis dislocation, correction of length (up to +21mm), save an old stem not mobilized, reduction of operation length.

The hip prosthesis dislocation, in spite of the continuous progress of implants’ materials and design, is still an actual event in the orthopaedic clinical practice, both after total hip replacement or a endoprosthesis. Furthermore, dislocation has an important social-economic impact because of a protracted hospitalization and rehabilitation and elevated costs of an eventual revision. Although using heads with a diameter larger than 28 mm we obtain virtually a greater range of motion, with a contemporary increase of degree necessary to cause the head-neck impingement, the risck of dislocation hasn’t a significant increase using head with a diameter of 22 mm.

Neck modular adapters (Bioball) allow to correct easily the biomechanics parameters of the dislocated prosthesic joint, avoiding the revision of the stem. Other indications for the use of the neck modular adapter are total hip replacement and intraoperatory correction of the limb length. Vantages are the possibilty to obtain a great range of motion through a small thickness of the 12/14 adapter, the possibility to extend the limb length up to 21 mm and to use ceramic heads during revisions, because the combination head/neck has a tribological unweared surface. In fact, in normal conditions, if the stem is not mobilizated, the use of ceramic head is rash; the Bioball adapter, instead, can be used with a old stem, so we can set a ceramic head. Every stem with a Biolox cone can be combined with a metal or ceramic head up to the 5XL size (+21 mm) through a Bioball adapter; in this way the cup is not removed.

We have two kinds of neck modular adapters: 12/14 allow both to extend the neck and to correct the offset, and 14/16 that allow to extend only the neck, because of the largest diameter of the prosthesic neck and the small thickness of the adapter. For these neck modular adapters exist different sizes, from M to 5XL (+21mm). Recently to these two types of Bioball were introduced also solutions for special stems (like for Exeter, ABG I, ABGII, PCA and others) We have also proving heads and necks. The proving and definitive heads have to be of the Bioball system because these are inserted on a modular neck with a no-standard diameter.

In the common practice the use of these adaptors has not to be considered as a routinary procedure, but have to be taken in consideration as a valid aid for orthopaedic surgeon to quickly and less invasively, solve technically demanding procedures with a real benefit for high-surgical risk patients.

Long-term stability of total hip arthroplasty (THA) depends on the integration between osseous tissue and the biomaterial implant. Integrity of the osseous tissue requires the contribution of mesenchymal stem cells and their continuous differentiation into an osteoblastic phenotype.

Some studies, like Wang ML et al., show that chronic exposure to titanium and zirconium oxide wear debris may contribute to decreased bone formation at the bone/implant interface by reducing the population of viable human mesenchymal stem cells (hMSCs) and compromising their differentiation into functional osteoblasts.

On the basis of our good experience in the use of Exeter technique in revision surgery of THA, two years ago we started to utilize bone grafts mixed with growth factors in order to improve grafts incorporation and implant fixation. At the moment we are studying the use of hMSCs during hip revision surgery, employing polyethylene cup to reduce the possible titanium and zirconium oxide debris. hMSCs are obtained with MarrowsStim Concentration Kit (Biomet Biologics Europe) by 60 ml of patient’s bone marrow.

Clinical outcomes and quality of life are evaluated on the basis of Harris Hip Score, Womac score and SF-36 score, while bone graft incorporation features are assessed with post operative computed tomography (CT) examination and further CT controls at two, four and eight months after surgery.

In the last months of 2007 we started to retrospectively review 60 patients who had undergone Girdlestone resection arthroplasty of the hip between 1994 to 2006.

The most frequent indications for this procedure were sepsis around prosthesis, aseptic loosening, pseudoartrhosis after femoral neck fractures or medical compromised patients who had an high risk of hip reimplantation procedure. The evaluation of patient’s satisfaction ranges a lot in literature and no valid guidelines have been publicated.

All our patients were submitted to limb shortening measurement and functional evaluation according to SF-36 score and Harris Hip Score. There were 20 men and 40 women with an average age of 70 years old (range 96-43 years old on operation time), the mean follow up was 133 months (range 14–167 months). Some patients were lost at the follow-up, the main reason was death for related and unrelated causes (overall mortality of 30%).

The aim of this study was to analyze patient’s satisfaction and functional outcomes after Girdlestone arthroplasty which appears in our experience, despite the limits, a valid surgical option in order to improve hip function, decrease or cancel pain and control infections when implantation or reimplantation is not possible.

Femoral off-set is the perpendicular distance between femur longitudinal axle and the femoral head’s rotation’s centre. Femoral off-set influences following yardsticks: stability of the joint, range of movement (ROM), muscular forcibleness, solicitations on the femoral component and acetabular component’s usury. From numerous radiographies studies, is shown as off-set is not an indefeasible measure, but an average with a range of variability. Offset is one of the most important yardsticks to consider during the pre-operating planning since, as is broadly documented, it has a positive effect on the functionality of the prosthesis; difficulty remains to individualize the optimal offset value in patient with bilateral coxofemural pathology or carriers of opposite side total hip prosthesis. Modular necks act indipendently in three spatial variables allowing to reach 27 points in the space, disposing of heads with three lenghts the real disponibility become of 81 points.

Usually we estimate the sizes and the orientation of the components manually and through a radiographic intra-operative control in order to choose the best match head-neck.

If we make a minimum mistake in cup position, the use of modular necks allow to correct this failure to obtain the most correct anatomic position producing negligible debris and the reduction of the mechanic stress.

Basing on our experience we think that the possibility to change length and version independently and sequentially is the unique technique avaible to correct the implant’s orientation, even if in our series we have choose neutral neck in most cases. To obtain better functional outcome we are studing a device based on gait analysis and superficial electromyography to calculate pre and post operative off-set. The data that we have achieved are still too few to be able to produce results; if there is possible, presenting them in future editions.

Great diffusion of hip prosthetic surgery, in relatively-young patients too, generates as consequence an increase in prosthesis failures associated with limited or massive bone losses, making revision surgery mandatory, even in most advanced degrees of osteolysis.

In best surgery strategy planning are essential: - evaluation of osteolysis degree with standard x-Rays; - evaluation of periprosthetic bone turn-over with scintigraphy (both a specific as they give merely qualitative evaluations of bone remodeling); – quantitative evaluation of periprosthetic bone mineral density with periprosthetic mineralometry (D.E.X.A.). Data obtained with these methods allow more accurate decisions, during the pre-operative phase, regarding the most indicated implant for revision surgery: mid or long-stem, with or without omoplastic transplants, with or without materials promoting bone rehabitation. In any case, the surgeon must have all possible solutions in order to eventually change the operative plan during surgical act.

Following qualitative and quantitative periprosthetic bone evaluations, we use to classify stem and cup mobilizations with Italian Group for Revision (GIR) classification. According to GIR classification, our actual trends in the choice of revision prostheses, in the most advanced degrees of complex mobilizations of stem and cup, are the following: - GIR 3 (Enlargement of the femoral shaft with thinning of cortical bone and loosing of 2 or more walls; loosening and acetabular deformation with losing of one ore more columns and the bottom). In this degree we prefer a long-stem concept straight prosthesis; this prosthesis allows an immediately more stable implant, due to optimized length, in opposition to rotation forces and assuring force transfer in both proximal and distal direction. When osteolysis is wider, it was necessary a strategy change, searching a more distal locking of the implant, according to Wagner’s criteria. The SL Wagner’s prosthesis restores cohesion with the reabsorbed bone surface, generating a relative stability in the immediate post-op period; in the following 2 months, an intense bone apposition, which brings to a progressive filling of bone losses, takes place. For this purpose, it is not indicated, apart from surgical way used, cutting the muscle insertions around the thinned wall. This revision prosthesis is fixed without the use of cement due to the distal blocking, guaranteed by his conical shape; the stem is straight and it is not fit to the natural front-bending of femoral shaft. For this last explained reason, we follow these guidelines, improving our results, using a cementless anatomic modular stem: with this kind of implant design, that preserves cortical bone of femoral shaft from stress shielding, and the extremely wide (XX combination) choice of head and neck components, we are now able to regain as well as possible, the correct offset and center of rotation. For the acetabular loosening, we use to implant oval cups, that naturally fit the acetabular lesion, with or without bone grafts impaction in bone loss areas.- GIR 4 (Massive proximal bone loss all around the shaft; massive peri-acetabular loss). In the past we implanted wide-resection cemented (Muller) or non cemented (Kotz) prosthesis, originally designed for onchologic patients, to treat complete femoral osteolysis. The wide resection uncemented prosthesis, after follow up, supports the Wagner’s theory of distal support, because in spite of an almost complete bone sacrifice, there is an attempt of periprosthetic corticalization by the femoral bone. Since some years we implant even in this cases a modular distally-anatomic revision prosthesis, this type of prosthesis, thanks to his proximal component, provides a relative primary metaphyseal support, that improves global stability of implant. In massive peri-acetabular loss we prefer the use of oval components with peripheral supports and obturatory hook, with bone graft impaction. Only as “extrema ratio” we choose for the implant a McMinn stemmed cup.

From these guidelines, integrated with clinical observation at mid range follow-up, appears clerarly that cementless prosthesis in hip revision surgery, even in most advanced degrees of osteolysis, are really able to guarantee good results for the patient. These patients, previously implanted with hip prosthesis, have intrinsic limitations of hip joint ROM, sometimes associated with muscular impairments; therefore it’s rarely possible to bring back the hip to an optimal degree of function, especially if compared with a normal joint. The goodness of long-term results must be therefore evaluated in relation to patient’s conditions before the operation itself, especially according to bone conditions regarding osteointegration of prosthesis. If follow up of patient is constant, allowing to program with good timing the revision surgery, if necessary, the use of cementless prostheses is a very powerful (nevertheless conservative) instrument for good functional recovery of these patients.

The use of metal-on-metal THA has taken origin from the use of Mc Kee prostheses in our Institute in 1967. In 3rd Division of “Istituto Gaetano Pini” in Milan have been performed more than 1300 implants of these prostheses between 1967 and 1983. The analyses of implant surfaces after removal have demonstrated an almost null debris and good liability regarding implant stability. Even if someone assumed, in the past, the carcinogenic effects induced by metal debris, recent publications showed no statistically significant differences in the incidence of cancer between patients treated with metal-on-metal prostheses and normal population. The very good results in follow-up and the evidence of limited debris of metallic contact surfaces have encouraged us to continue with this experience using large head prostheses with metal-on-metal interface.

We implanted 73 Artek cup in 1997–2000 years, an uncemented pre-assembled cup, fixed by pure press fit. The advantages with this cup derived from his low profile (1/3rd of sphere) and contemporary use of large diameter heads (38 mm), similar to McKee’s model (35–41.5 mm). This design allowed us not only to preserve bone-stock, but even to reduce displacement risk. These advantages were increased by the absence of interposed PE surfaces, which inevitably suffer from time-related degeneration. In the last years we increase the use of hard surface THA, usually performing the implant of pressfit cups with metallic liner and large diameter heads (32 and 36 mm) or ceramic-ceramic interface. We believe in better indication (null-wear) of ceramic-ceramic THA in < 60 years patients (even in older ones high functional requests). Usually > 60 years we implant metal-on metal THA: we think that can guarantee very low debris rates and, if used in association with modular components and large diameter heads, a sensibly increased ROM and lower displacement rate.

We implanted 73 Artek cup in 1997–2000 years, an uncemented pre-assembled cup, fixed by pure pressfit. The advantages with this cup derived from his low profile (1/3rd of sphere) and contemporary use of large diameter heads (38 mm), similar to McKee’s model (35–41.5 mm). This design allowed us not only to preserve bone-stock, but even to reduce displacement risk. These advantages were increased by the absence of interposed PE surfaces, which inevitably suffer from time-related degeneration. In the last years we increase the use of hard surface THA, usually performing the implant of pressfit cups with metallic liner and large diameter heads (32 and 36 mm) or ceramic-ceramic interface. We believe in better indication (null-wear) of ceramic-ceramic THA in < 60 years patients (even in older ones high functional requests). Usually > 60 years we implant metal-on metal THA: we think that can guarantee very low debris rates and, if used in association with modular components and large diameter heads, a sensibly increased ROM and lower displacement rate.

The common use of hard surface THA has to be considered “gold standard” even in the elderly, in a constantly increasing mean-life era with corresponding better quality of life: we believe that is mandatory to offer, even to these patients, a long-lasting and high result hip arthroplasty.

The constant increase in number of hip revisions during last years has lead to a consequent increase even in fracturative events of the femoral shaft. The treatment of these kind of fractures have to be considered like the one for « pathologic fractures », due to periprosthetic or pericemental osteolysis that occurs in prosthesis’ mobilization, reducing drastically the bone resistance.

We use to divide these fractures primarily in two groups:

Pathologic Fractures, occurring before revision surgery.

Surgical solutions are different, according to fracture’s level and severity. TYPE 1 Fracture limited to trochanteric region TYPE 2 Fracture not exceeding stem length TYPE 3 Fracture line from shaft to distal part of the stem TYPE 4 Fracture line completely under femoral stem TYPE 5 Plurifragmentary fracture

For 1st group, surgical solution is to stabilize trochanteric region with dynamic wiring. For 2nd group, plate with both screws and dynamic wires are indicated. The fractures of last three groups are successfully treated with cementless long stem prosthesese, eventually associated with plate. In summary, the modern techniques of revision surgery associated with systems of cement removal (ultra-sounds and re-cementing procedures) have permitted to decrease the number of periprosthetic fractures. We think that the use of last generation models of cementless modular stem for revision, associated with dynamometric wiring, always allows brilliantly solving this complex surgical problem.

In congenital and acquired angular deformities of the coxofemoral joint, hip prosthesis presents considerable difficulties. The aim of this study is to analyse the different surgical solutions for this problem.

In the geographical area of G. Pini Institute, where congenital hip dysplasia is endemic and where also historically the surgical outcome of various types of osteotomy (both acetabular and femoral) have been investigated, this problem has often been encountered. We have evaluated several parameters, also with respect to particular cases in which tailored prosthetic solutions were required, to establish which kind of prosthetic treatment is most reliable today.

From 1994 to 2002 more than 6000 surgical hip prosthesis procedures were carried out at our institute: 750 in dysplastic hips and 112 after osteotomy. In our clinical division we also evaluate patientsin the pre-surgical phase with the DEXA, which gives qualitative and quantitative data about peri-prosthestc bone. After the first period of using standard, customised prostheses with no modular neck, we have progressively increased the use of a modular stem with press-fit cups that guarantee minimal bone sacrifice and a good recovery of articular biomechanics. In particular, with the use of modular components for the head and neck it is easy to reinstate the centre of rotation and achieve good offset and good lower limb length, without “escamotages” such as the use of a larger stem not perfectly inserted in the femoral diaphysis and the non-physiological cup position to avoid the risk of luxation.

We have progressively abandoned the use of PE, which is the cause of debris and should be avoided in angular deformities: in patients under 65 years of age we use ceramic-on-ceramic bearing surfaces with monob-lock insert, whereas in patients over 65 we prefer to use metal-on-metal bearing surfaces (always monoblock).

Deformities caused by the same pathological condition resulting in surgical osteotomy make implantation of standard prosthetic models impossible; our surgical experience suggests the use of different prosthetic models.

The use of custom-made prostheses has progressively been reduced thanks to the development of suitable modular prostheses which suit these patients perfectly.

In the past few years the use of cemented prostheses in these patients has decreased: according to our experience the use of cementless prostheses in relatively young subjects allows a good range of motion but above all it is useful to preserve bone in view of a possible future revision.

Since 1989 more than 5000 Zweymuller stems have been implanted in the Orthopaedic Institute G. Pini, Milan, Italy. This uncemented stem which has been produced since 1979 nowadays is though to be one of the best prothesical solutions and this can be affirmed both on the easy operative techniques and on the bases of our clinical studies of follow up. This is also the most used uncemented coxofemural system in Europe. The advantages in the Zweymuller design are due to the rotatory stability and the slight volume of the implant, which in the international literature are referred as the key points of this success. The bone anchorage and the distribution of the weights is achieved both proximally and distally thanks to the conical stem, which in the proximal region is anchored on one side by the great wing of the trocanteris on the other side by the wedge effect.

In the distant cortical instead the borders of the stem get wedged in the bone. This very wide anchorage allows a great stability reflected also by the lack of weigh pain at diafisys level.

The same stem is used both for first implant as well as revisions (after evaluation of the bone stock, achieved in our studies by dexa) but also for intertrocanteric osteotomies.

The chance of a rapid mobilization of the patient makes this stem convenient also in geriatric orthopaedic cases. The material is a alloy of Ti, Al and Nb: this material has been studied directly for medical appliances and not only it doesn’t contain toxic or allergenic components but provide an high resistence to breaks. Osteointegration is favoured by the rough surfaces.

In our last clinical study on the follow up of patients treated with this kind of implant in the last 18 months we have seen a difference in those cases in which a pneumatic driver for nailing had been used in the operative room. Not only the operative time for the positioning has been reduced of one third but the implant resulted to be more precise.

The use of this driver allows a better fitting of the stem to the femural shaft as the cut is more precise. In fact the surgeon has a controlled magnitude and direction of the driving force and this force is anyway limited.

There is a remarkable reduction of cases of intra operative fractures. So we have collected datas on 70 randomized patients in whom this device had been used compared to the same number of patients operated without this apparel: the operative time is reduced of 15 minutes in average and as a consequence the risk of fat emboly has diminished; revisions for malpositioning and intraoperative fractures are almost worthless. Moreover the blood loss has reduced of 100 cc. This are only partial datas but seem to suggest that this device can provide a great help to the orthopaedic surgeon in the operative room as well as reducing complicances in patients: we plan that this driver together with the Zweymuller stem will represent in the future one of the most safe solution in the total hip replacement when the surgeon puts the indication for an uncemented implant.

In this work we mean explain our clinical experience about the use of a T.R.K. mobile meniscal bearing implanted during the 2000 and 2001 in our institute. The prostheses design allows the motion of the polietilenic component 5mm in the anteroposterior directions and 12.5 degrees in the internal and external rotation.

In association with the shaping of the femural contact surfaces this design allows a huge upgrade of contact surfaces compared with other protheses already in use. We have evaluated 17 patients on short term follow up, patients operated in our division, four males and 13 females. The average ages are 68 ± 8.

The indication was in all cases gonartrosis. The evaluation protocol includes:

§ Pre and post operative x rays (after 60 days);

§ Clinical evaluation of the range of motion;

§ D.E.X.A. mineralometry;

§ Stabilometric evaluation pre operative and after 6 months.

The first results have pointed out the disappearing of pain in all the patients, an optimal recovering of the articular function with no loss of extension, a good prothesic osteointegration (even in an initial phase in our cases) and the stabilometric evaluation confirms a soon proprioceptivity recovering and the motion of the operated limb.

After all this encouraging results we have decided to continue implanting this kind of protheses as we think that not only it warrants a better range of motion, but the utmost null polietilenic debris may allows a longer life to the implant as a consequence of the reduced stress rate.

The pre operative evaluation of the degree of osteolisys in cotyle revision in a prothesis is very important in order to plan the best surgical treatment.

In these cases above the traditional radiological and scintigrafic exams we have achieved a evaluation techniques bases on D.E.X.A. This technique allows obtaining data on the periprotheses bone stock. These are the criterion of choice of the revision protheses, keepin’ in consideration data acquired by D.E.X.A.:

GIR 1 (loosening and acetabular widing with persistence of walls). If the cotyle is uncemented and the biological age of the patient allows, we use to treat with a first implant press fit uncemented cotyle.

Conclusions: As a conclusion we can maintain that these indication may supply satisfactory datas thanks to the deep pre operative evaluation by DEXA. We have to keep in consideration that this pathology must be considered urgent: as soon as the operation is achieved the better bone stock will be available to the surgeon. The use of many kind of uncemented cotyle allows us, today more than ever, to restore the correct center of rotation without the risk of further mobilizations.

The great diffusion of total hip replacement in young patients has generated as a consequence an increasing in the number of prothesic failing associated with more or less extended bone loss. We mean analyze the various surgical solution to this problem. In the planning of the best surgical treatment the evaluation of the degree of osteolysis is the more correct technique; in fact we have supported the classical radiological exams with the miralometry as DEXA (supplying quantitative data on the periprotesic bone stock). Data obtained in this way allow choosing more carefully the best protheses in the preoperative planning: mid or long stem, with or without bone graft, with or without materials which may promote a bone rehabilitation. Anyway the surgeon should have all the possible protheses solutions as it happens to change the operative plan during the operation. These are the criterion of choice of the revision protheses, keepin’ in consideration data acquired by D.E.X.A.:

GIR 1 (loosening and or widing of the femural shaft with reducing of the cortical without interruption of walls): If the mobilized protheses is uncemented and DEXA supplies datas about a good bone stock we try to use a first implant uncemented protheses

Kotz’s design, on the bases of follow up studies, seem to support Wagner’s theories about the distant anchorage: There is an attempt of periprothesic corticalization even though the huge bone loss. In the last years we have performed a revision modular distally anatomic stem characterized by a metafi sarial leaning on the proximal component.

The weight bearing is progressive on the base of the radiological evolution and DEXA as well. The complete bearing will be allowed only after a sufficient bone restoration.

In our experience uncemented protheses in the stem revision can allow in mid and long term good results expecially keeping in consideration that these patients had already coxofemural problems. The range of motion is difficulty improvable so the results must be weighted on the bases of the previous clinical situation. If patients are monitored in order to operate as soon as possible in case of mobilization, the use of uncemented protheses can be a valid way for the functional recovering of these patients.

The actual data about prevalence of knee osteoarthritis, the concurrent increasing of mean age and therefore the high social costs for the care of this pathology, make particularly important to do the correct choice in knee artroprosthesis. In this work we mean compare three different type of knee prostheses implanted in our institute. We have evaluated 120 patients (98 females, 22 males) treated with TKR in I° Orthopaedic Division of Istituto Ortopedico “Gaetano Pini” – Milano. All patients were affected by primary knee osteoarthritis of high degree and 3 groups were made due to the type of prosthesis implanted.

Our evaluation protocol includes: 1. Local objective examination and evaluation of Range of Motion (R.O.M.); 2. Subjective functional questionnaire (Lequesne Index modified for knee osteoarthritis); 3. Stabilometric evaluation for Proprioceptive knee structures (KAT-2000 Breg Inc. USA); 4. Standard X-Ray, both in AP and lateral planes, with patient in standing position.

The X-Ray controls showed no early mobilisations or malfitting of all implants. In consideration of the short follow-up period we have to do a continuous monitoring for at least 5 years to express a definitive evaluation of implant stability; significatively better results regarding the post-op R.O.M. and subjective results with Lequesne Index have been obtained with the use of mobile plate prosthesis.

The first results have pointed out better results in the use of a fully mobile plate prosthesis, compared with the other results using rotating and fixed plate prostheses.

In our opinion this is obtained through the research of a better reproduction of human anatomy and trying to respect the common kinematics of knee, which has to be the future objective in design and technical development of knee arthroplasty.

The various surgical prosthetic solutions in coxarthrosis on a dysplastic basis were evaluated in a critical way.

In our institute more than 3,750 hip prostheses were implanted from 1994 to 1999, and 366 (9.76%) were used for dysplastic coxarthrosis. This high percentage can be explained by the particular geographical position of our institute that has patients coming from the Lombardia region area where CDH is endemic.

Our evaluations consider the highest number of possible parameters in order to realize which is the most modern and reliable surgical solution. Of course, each case is individual and our advantage is to have a prosthesis that is the most suitable for each patient.

The number and type of prostheses used were: 27 ABG, 35 CONUS, 25 CUSTOM MADE, 7 HN, 5 MALLORY, 35 OMNIFLEX, 3 PARHOFER PLASMAPORE, 4 PERSONALISED CUSTOM MADE, 3 RIPPEN, 18 RMHS, 45 SAMO PG, 130 ZWEYMULLER, 18 P507, 6 OMNIFIT, and 5 GYPSE.

From our unique perspective we can consider that in the last several years the use of a cemented prosthesis is progressively disappearing (less than 13%). The use of a cementless prosthesis in young patients (age range 20 to 65) preserves bone stock during implantation, placement and replacement when necessary. If the patient’s age and general conditions allow, we generally operate both dysplastic hips in one stage.

All cases were evaluated with DEXA, which provides qualitative and quantitative data about the periprosthetic bone stock. Various parameters were studied, including restoration of normal biomechanics, centre of rotation, equalisation of limb-length, the Trendelenburg sign, and nerve complications.