Near 70% of failures of knee arthroplastys due to septic or aseptic mobilization are complicated because of massive loss of bone stock. In these cases surgeon have to perform a salvage procedure to restore legamentous balance, articular plane direction and axes of lower limb, finally to fill bone defects. Today intrinsic biomechanical stability of revision implant is entrust to sophisticated design and materials of custom made and modular implants. Endomedullary stem has to assolve specific functions: mechanical stability contrasting stress due to the boneloss, offering support for omoplastic or spongious bone innests in femoralor tibial defects. There are paucity of study in literature about dimension and morphology of endomedullary canal, probably because of variability between periostal andendostal anatomy in each patients, specially age related. This date has conditioned production of several number of revision stem size for all population. This anthropometric study verify presence of a particular regionin femoral and tibial endomidullar canal not dependent from sex, height, morphotype, important for a good press-fit of revision stem.

Morphological date of midfemoral and tibial geometry was assessed in 50 subjects using Axial Computerized Tomography. Eleven (22%) were in men, thirty nine (78%) were in woman, with avarage of 73 years old (from 57 to 85). Exclusion criteria were previous operation at the same limb, deformity, pathology of bone metabolism. The level of sections were at 20, 18, 16 and 12 centimiters from articular plane for femur and at 8, 10, 13, 16 cm for tibia. Preliminar Ct scan with hight resolution program with bone alghoritm was performed. Axial view of any section was visualized at real dimension and maximal and minimal diameter of sections e were measured in millimiters.

Areas of any section is different in each patient; this variability is greater near articular plane. Infact in our sample SD (Standard Deviation) of diameters of proximal femoral and distal tibialsections was lesser than SD of the other measurements. No difference of results about sex was noted. On base of these measuremts more proximal two femoral sections and two more distal tibial sections were considered to elaborate an ideal area for anchorage zone of anatomical revision stem. We subdivided all sample in five groups with homogeneous value of diameter in selected sections. For any groups tangent & #945; of an ideal trunk of cone including maximum and minimum value of diameter considered was computed, and the relative inclination angle. In our sample the greatest diameter in proximal femoral section was 20 mm and the lowest 10 mm; for tibial measuremnts the greatest value in distal tibial level was 18 mm and the lowest was 10 mm. Inclination angle was ever around 2° in all groups. Moreover we have calculated the presumable length of an ideal trunk of cone that includes the minimum and maximum value of femural and tibial diameter measured.

About 5% of knee arthroplastys is destinated to an unsuccessfull. In many cases loosing of bone stock is huge and localized near articular plane. Afterward it’s important to restore biomechanical stability through endomedullary stem of revision implant. There are not many reports about morphology and anatomical study of femoral and tibial endomedullary canal. Many authors focus the attention on bone density or functional axes of the lower limb. Some authors studied remodelling process age-related about periostal ad endostal bone; cortical area undergoing thinning specially over fourthy years old. Our sample had mean of 73 years old: remodelling process is almost complete and then it is a good referenceto extrapolate real data about endomedullary morphology and width. Variability of data in all population about diameter of endomedullarycanal is lesser near femoral and tibial istmo, in particular around 18–20 cm from articular plane for femur and at 13–16 cm for tibia In our opinion short stem can’t guarantee good press-fit because of extreme variability of diameters in the population near knee. This anthropometric study confirm presence of anatomical area of the midfemural and tibial canal with common geometric characteristic in allpatient; it can be used to realize an anatomical stem that guarantees a good contact bone/prosthesis and then an optimal bone integration. On base of our results it is possibile realize few revision stem because in all groups of patients studied at 18–20 cm from knee for femur and at 13–16 cm for tibia, angle of inclination was ever 2°.

Asepting loosening by polyethylen wears is on of the main problems in total knee replacement. In the last years, the major improvement is about matherials. The polyethylene remains the major problems for long term results of total knee replacement despite new types of polyethylenes like cross linked or high reticulation. From to 2 years a new matherial (Oxinium) for femoral component has been avaluated; Oxinium is an high temperature and oxidation procedure to trasform the articular surface like a ceramic. In this paper early results with this total knee replacement are reported and the advantages of this new matherial are discussed.

110 primary Oxinium-Profix were evaluated. Mean follow up is 18 months ( min2 max 26). Mean age is 67 years (53 yrs– 74yrs). Both components were cemented. In all cases PCL was retained. Never patella was replaced. Lateral release with out-in technique was performed in all cases. The Knee Society scoring system was used to assess patients both clinically and radiografically.

Clinical and radiographic results are promising despite the short follow-up. Oxiunium seems to be a safe matherial, especially for young patients because of low rate of wear. However, only a long term follow up could confirm the intial promising results

Bone Loss is the main problem in failed total hip arthroplasties. Revision surgery must be conformed to the degree of the bone loss. Since 1986, 330 cases of failed THA underwent to revision surgery. Different solutions were adopted according to Paprosky femoral defects classification. In type I, a primary cementless stem was implanted (23%). In type II and IIIa, were proximal fixation is still possible to achieve, Mid PCA-Howmedica (5%) and modular S-ROM-J& J revision stems (18%) were implanted. In all the other degree of bone loss (IIIb–IV) cementless distal fixation stems, Long PCA-Howmedica (17 %), Wagner-Sulzer (18 %) and modular (MP-Link, Profemur-Wright) (19 %), were used. Patients were clinically and radiographically evaluated by HHS and according to Engh’s criteria. Best results were observed in Type I group (HHS=90). Long and mid PCA stems presented poor clinical (HHS=60) and radiographical results and required re-revision in 15% of cases. Intermediate results were observed in Wagner prostheses. Modular revision stems showed best results although earlier F-U. (HHS=80). Of these, re-revision surgery was performed in two cases, one of which because of infection and the other one due to severe thigh pain.

Cementless modular stems seem to be the most suitable technique. Distal fixation associated with proximal fill permit to manage the majority of femoral bone defects minimizing bone grafts. The modular stems, allow to conform the design of the components to the bone defects permitting to achieve primary stability (press-fit), restoring the centre of rotation and muscles tension, reducing pain and restoring hip function.