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Background and Aim: Number of hip prosthesis implants in arthritis, number of patients treated with bisphosphonates to prevent fragility fractures and, together, number of atypical femoral fracture's cases are increasing., Case Series: This article describes two cases of hip arthritis, treated with hip replacement, in patients using bisphosphonates for a long time; in both cases an incomplete atypical femoral fracture was misdiagnosed before the surgery. Authors describe the importance to carry out a complete osteometabolic and radiographic pre-operative examination of patients in treatment with bisphosphonates going to hip replacement, to check the possible presence of incomplete atypical femoral fracture and to optimize surgical and pharmacological treatment., Conclusions: In hip prosthesis surgery, prior diagnosis of incomplete atypical femoral fractures can indicate the choice of a different kind of prosthesis stem to optimize surgical results. This can also positively impact to rehabilitation in term of duration and daily activities recovery.

Restoring bone loss is one of the major challenges when facing hip revision surgery. To eliminate the risk of disease transmission and antigenicity of allografts and donor-morbidity of autografts, the use of synthetic bioceramics has become popular in the last decade. Our study investigated the effectiveness of impaction bone grafting (IBG) of contained acetabular defects (Paprosky 2 and 3a) using a porous ceramic-based hydroxyapatite bone substitute (Engipore, provided by Finceramica Faenza S.p.A., Faenza, Italy) mixed with a low percentage of autologous bone (obtained from reaming when available). We retrospectively assessed 36 patients who underwent acetabular revision using IBG using a porous ceramic-based hydroxyapatite bone substitute with cementless implants with a mean follow-up of 4.4 years. We evaluated, at regular intervals, patients clinically (using the Hip Harris Score and Oxford Score) and radiologically to evaluate the rate of incorporation of the graft, the presence of radiolucent lines or migrations of the cup. Clinical scores significantly improved (WOMAC improved from 49.7-67.30, and the HSS from 56-89). The rate of implants' survival was 100% at our medium follow-up (4.4 years). We reported five cases of minor migration of the cup, and radiolucent lines were visible in seven patients at the last-follow up. The graft was well-incorporated in all patients. The results presented in this study suggest the HA bone substitute is an effective and safe bone graft when facing hip revision surgery; thus, longer follow-up studies are required.

Introduction: Total hip arthroplasty is one of the most performed procedures in orthopaedic surgery. Implantation of a prosthesis determines changes in the distribution of loads on the host bone, and this phenomenon, known as stress shielding, is related to the biomechanical characteristics of the implant. Usually stress shielding involves the proximal portion of the femur by reducing the mechanical strength and ability to withstand the transmitted loads. The aim of our study is to demonstrate how the use of a short hip stem reduces the stress shielding phenomenon to the proximal femur., Materials and Methods: The study analyzed 20 patients undergoing hip prosthesis surgery with a short stem (Metha<, B. Braun Medical, Inc., Bethlehem, Pennsylvania) at the Ist Orthopaedic Division of Pisa University (between December 2008 and January 2010). Each patient was subjected to analysis of periprosthetic bone mineral density by a bone densitometry (dual emission X-ray absorptiometry [DEXA] with the metal removal software) at 0, 6, 12, 18, 24, and 36 months, following a protocol based on the evaluation of the changes of bone density in the seven Gruen zones., Results: We recorded minimal changes in bone mineral density (BMD) at the level of the greater trochanter (-1.44%) and at the level of the calcar (-3.7%). BMD increased significantly after four years at the level of the lateral distal regions (R2 +9.6% - R3 + 12.4%) and at the level of the distal medial regions (R5 + 8.2% - R6 + 13.1%). We compared the results obtained with the literature data at 12 and 24 months with the same stem (Metha<). At 12 months follow up, we did not see a significant difference between our data and the data published in the literature. However, after 48 months of follow-up, we recorded significant differences in the curves of periprosthetic bone reabsorption at the level of the greater trochanter (Zone 1) and at the level of the calcar (Zone 7)., Discussion: The data obtained from our study are in agreement with other studies in the literature, which demonstrates how the use of short stems preserves the metaphyseal bone stock at the level of the proximal femur, reducing the stress shielding phenomenon. From our data, obtained at 24 months and confirmed at 36, stress shielding seems to minimally occur at the level of the calcar. At the level of the great trochanter, we saw a good load distribution that maintained the baseline BMD; these data are in opposition to the literature data that showed a high increase of BMD at the level of the calcar (+12.9%) and a decrease at the level of the great trochanter. From the analysis of the radiographic images of our cases, and of the cases published with the same stem, these differences in load transfer encountered between the great trochanter and the calcar seems to be related to the level of the femoral neck osteotomy and the consequent stem position (varus/valgus)., Conclusion: We conclude that the amount of periprostetic bone reabsorption around the Metha< stem seems to be strictly related to the surgical technique and the final implant position.

Acetabular cup loosening is associated with pain, reduced function, and instability of the implant. If such event happens while the femoral implant is in a satisfactory position and is well fixed to the bone, isolated acetabular revision surgery is indicated. The aim of this single-center retrospective study was to evaluate the clinical and radiological results over the medium term (12-month follow-up mean 36, max 60) of isolated acetabular revisions surgery using a porous hemispheric revision shell matched with a cemented all-poly cup and large diameter femoral head (>32). 33 patients were enrolled. We collect any relevant data from the clinical board. Routine clinical and radiographic examinations were performed preoperatively; the postoperative follow-up was made at 1, 3, and 6 months and yearly thereafter. At the last available follow-up, we report satisfactory improvement of functional scores in all the patients; 2 patients (6.1%) showed thigh pain and only 4 hips (12.11%) presented mild groin pain; all the femoral components are well fixed and there were no potential or pending rerevisions. With bias due to the follow-up and to the retrospective design of the study, we report clinical, functional, and radiological satisfactory results.

Introduction: Initial stability with press-fit cups can be achieved in a number of ways based on the design of the cup. With line-to-line fit, screws fixation, press-fit of 1 to 2 mm which is obtained by an oversized hemispherical cup, initial stability can be achieved with the dual-radius press-fit cups, which have an equatorial diameter 1 to 2 mm greater than that of the polar diameter, to ensure a good press-fit and to provide adequate initial stability for bone ingrowth to occur reliably., Methods: Between January 2002 and January 2008, 400 total hip replacements (THRs) were carried out. We examined the first 150 consecutive primary THRs. In all hips, the acetabular component was the dual radius Trident AD shell (Stryker Orthopaedics, Mahwah, New Jersey)., Results: The median duration of follow-up was 6,2 yrs (range, 5 to 7 yrs). The median post-operative Harris Hip Score for 150 hips was 90.5 (range, 51 to 98). At the time of the latest follow-up, there was a bony incorporation of all components; we found no definite evidence of radiographic loosening and no signs of radiolucency., Conclusion: According to the encouraging results of the present study we conclude that the Trident cup is a valid choice for acetabular replacement.