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 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 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 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.