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

Aims: Bone stock preservation is crucial when performing THR in young patients. Previous experiments have confirmed that a physiologic load transfer to the proximal femur has several advantages. First, there is experimental evidence (Fetto et al) that loading the medial and lateral flare effectively preserves in time metaphyseal bone stock. Second, biomechanical tests (Walker et al) have confirmed that with this kind of stress distribution it is possible to remove the diaphyseal portion of the stem.

Following this philosophy, an original ultra-short stem with extensive proximal load transfer was developed. Purpose of this paper is to present clinical and radiological results at 4 yrs average follow up.

Methods: Since June 1995, we implanted 118 stems in 101 patients. Average age at the time of surgery was 51 yrs (30-63) All operations were performed by the senior Author (FFS). Particular care was taken in preserving all the femoral neck and the trochanteric muscles. All implants were customised based on pre-operative CT data. Harris Hip Score (HHS) formed the basis of the clinical assessment. Serial post-operative AP and lateral radiographs were taken for all patients.

Result: Patients were followed-up for up to 9 years (mean follow-up 45 months) and results showed no stem related revisions or infections. The mean HHS increased from 44.8 pre-operatively to 98.6 post-operatively at the latest follow-up. Tight pain was recorded only in one case. Other complications included 2 dislocations, one trapped drain and 2 superficial wound infections. All stems appeared radiografically stable with a well maintained proximal bone stock. No radiolucent lines have appeared around the stem.

Conclusions: Results obtained in this group of relatively young patients have been encouraging. Clinical and radiographic results validate the assumption that torsional loads can be controlled even without the diaphy-seal portion of the stem. Neck preservation combined with lateral flare support guarantees a more natural loading of the femur. The absence of the stem makes this implant ideal for less invasive surgery.

Aims: Bone stock preservation is thought to be essential when performing THR in young patients. For this purpose we developed a new CAD-CAM titanium cementless femoral stem to be implanted with minimal femoral resection. This implant is constructed to þll completely the proximal metaphysis transferring loads on both the lateral ßare and the calcar. This allows the elimination of the diaphyseal portion of the stem which is prolonged only till approximately 1 centimetre below the lesser tro-canter. Methods: Since 1995, we implanted 76 stems in 71 patients. Average age was 51 yrs (30–63), 34 females and 37 males. Mean follow-up is 45 months (min.12, max 84 months). In all cases we employed an hemispherical pressþt cup. Metal to polyethylene interface was used in the þrst 30 implants whilst metal to metal coupling was chosen for the latter 46 hips. Clinically patients were evaluated with Harris Hip Score. All patients ware evaluated by X-ray 1, 3, 6 and every year postoperative. Results: Average preoperative value of HHS was 42,4, postoperative 98. Tight pain was never recorded. All the stems appear stable radiograþcally, we had no subsidence, no radiolucent lines, no stress shielding, no osteolisis. In 26,4% of cases we had mild proximal calcar resorption. Conclusions: Clinical and radiographic results conþrm that axial and torsional loads can be properly controlled even without the distal portion of the stem. We believe that maximal bone stock preservation in young patients undergoing THR is mandatory in view of the high possibility for these patients to require multiple revisions in the future.