Introduction. The following study start from an idea of the evaluation of the osteointegration in the bone cage of the Equinoxe Reverse shoulder prosthesis. The aim of the study is to assess the values of Bone Mineral Density (BMD) in periprosthetic areas, in patients undergoing shoulder arthroplasty with implants of the Equinoxe system by Excatech, Inc. To better understand the steps of osteointegration time of the bone cage with the glenoid. The objectives of the work are not only expanded to the value of osteointegration, but could also be useful for the evaluation of both mechanical and septic loosening of the stem of the glenoid. Materials and Methods. In the period from November 2011 to May 2012, 15 patients were evaluated. All patients were subjected to bone densitometry type of DXA within the first 15 days after surgery and at 3 months after surgery. The patients are all part of a homogeneous group for anatomical glenoid. Were excluded from the study all patients who were no significant alterations of the head and the glenoid. The acquisitions were performed with the patient in an oblique position, with limb in a neutral position, in order to obtain images in the coronal plane “true” of the joint. Were subsequently calculated values of BMD is around the stem with the 7 areas used by Gruen for the hip prosthesis and peripherally to the central peg using 3 areas, superiorly, medially and inferiorly to the same. Results. The values obtained showed a significant increase in the time of bone density peripherally to the central peg demonstrating a significant osteointegration. Being a prospective study these values will be integrated with new acquisition DXA to 6, 9, 12 months, 2, 3 and 5 years. Conclusions. Although preliminary, through our study it was possible to obtain the standard values of BMD in patients with prosthetic replacement has been successful. These BMD values represent a standard of reference for the physiological osseointegration; in the future must be evaluated for their variation in patients with prosthetic loosening and / or with infectious processes, in order to allow an early diagnosis of these diseases by studying DXA. Also in future studies BMD values obtained by us of the Equinoxe prosthesis can be compared with those obtained in other models of the shoulder prosthesis to detect any advantages or disadvantages in terms of osteointegration

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMDMethods: 119 patients were randomised to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. All surgeries were performed via the posterior approach with mobilization on the day of surgery. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years and compared to the unoperated contralateral femur as a control. Patient reported outcome measures of pain, function and health were also included at these corresponding follow-ups. BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% inthe mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures. This study demonstrated maintenance of femoral BMD in three different cementless femoral stem designs, with all achieving excellent improvements in patient reported outcomes. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship

Low-energy fractures complications are a major public health issue that make osteoporosis even worse. In sub-Saharan Africa, the prevalence of osteoporosis varies from 18.2% to 65.8%. There was no change in bone mineral density between HIV-infected and non-HIV-infected women in Sub-Saharan Africa, where HIV is widespread. Other investigations that demonstrated that HIV-infected people had poor BMD both before and after starting anti-retroviral treatment did not consistently show a low BMD finding. Inflammation-mediated bone remodelling has been associated with low BMD in HIV-infected patients. Antiretroviral Therapy has been demonstrated to exacerbate bone loss in addition to the pre-existing intrinsic risk of developing osteoporosis. Question: Is there loss of bone in HIV-infected patients before initiating ART?. The patients who were HIV-positive and enrolled in the ADVANCE research were retrospectively reviewed on a desk. All of the 1053 individuals in the ADVANCE research had a DXA scan performed to evaluate BMD as part of the initial screening and recruitment approach. The ADVANCE research enrolled HIV-positive people and randomly assigned them to three ART arms. A total of 400 patients were reviewed. Of these 400 records reviewed, 62.3% were female. 80% of the participants were younger than 40 years old, and 3% were older than 50 years. 82% were virally suppressed with less than 50 viral copies. The prevalence of osteopenia was 25.5% and osteoporosis was 2.8%, observed in predominantly African female participants aged between 30 and 39 years. The findings of this study confirm that there is pre-existing bone loss among HIV-infected ART naïve individuals. Approximately 28.3% in our study had clinically confirmed evidence of bone loss and of these, 2.8% of the entire cohort had osteoporosis. Bone loss was most prevalent in black females who are virologically suppressed

In conventional DXA (Dual-energy X-ray Absorptiometry) analysis, pixel bone mineral density (BMD) is often averaged at the femoral neck. Neck BMD constitutes the basis for osteoporosis diagnosis and fracture risk assessment. This data averaging, however, limits our understanding of localised spatial BMD patterns that could potentially enhance fracture prediction. DXA region free analysis (RFA) is a validated toolkit for pixel-level BMD analysis. We have previously deployed this toolkit to develop a spatio-temporal atlas of BMD ageing in the femur. This study aims first to introduce bone age to reflect the overall bone structural evolution with ageing, and second to quantify fracture-specific patterns in the femur. The study dataset comprised 4933 femoral DXA scans from White British women aged 75 years or older. The total number of fractures was 684, of which 178 were reported at the hip within a follow-up period of five years. BMD maps were computed using the RFA toolkit. For each BMD map, bone age was defined as the age for which the L2-norm between the map and the median atlas at that age is minimised. Next, bone maps were normalised for the estimated bone age. A t-test followed by false discovery rate (FDR) analysis was applied to compare between fracture and non-fracture groups. Excluding the ageing effect revealed subtle localised patterns of loss in BMD oriented in the same direction as principal tensile curves. A new score called f-score was defined by averaging the normalised pixel BMD values over the region with FDR q-value less than 1e–6. The area under the curve (AUC) was 0.731 (95% confidence interval (CI)=0.689–0.761) and 0.736 (95% CI=0.694–0.769) for neck BMD and f-score. Combining bone age and f-score improved the AUC significantly by 3% (AUC=0.761, 95% CI=0.756–0.768) over the neck BMD alone (AUC=0.731, 95% CI=0.726–0.737). This technique shows promise in characterizing spatially-complex BMD changes, for which the conventional region-based technique is insensitive. DXA RFA shows promise to further improve fracture prediction using spatial BMD distribution

To explore a novel machine learning model to evaluate the vertebral fracture risk using Decision Tree model and train the model by Bone Mineral Density (BMD) of different compartments of vertebral body. We collected a Computed Tomography image dataset, including 10 patients with osteoporotic fracture and 10 patients without osteoporotic fracture. 40 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients with osteoporotic fracture in the CT database and 53 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients without osteoporotic fracture in the CT database. Based on the biomechanical properties, 93 vertebral bodies were further segmented into 11 compartments: eight trabecular bone, cortical shell, top and bottom endplate. BMD of these 11 compartments was calculated based on the HU value in CT images. Decision tree model was used to build fracture prediction model, and Support Vector Machine was built as a compared model. All BMD data was shuffled to a random order. 70% of data was used as training data, and 30% left was used as test data. Then, training prediction accuracy and testing prediction accuracy were calculated separately in the two models. The training accuracy of Decision Tree model is 100% and testing accuracy is 92.14% after trained by BMD data of 11 compartments of the vertebral body. The type I error is 7.14% and type II error is 0%. The training accuracy of Support Vector Machine model is 100% and the testing accuracy is 78.57%. The type I error is 17.86% and type II error is 3.57%. The performance of vertebral body fracture prediction using Decision Tree is significantly higher than using Support Vector Machine. The Decision Tree model is a potential risk assessment method for clinical application. The pilot evidence showed that Decision Tree prediction model overcomes the overfitting drawback of Support Vector Machine Model. However, larger dataset and cohort study should be conducted for further evidence

Purpose. The purpose of this study was to evaluate periprosthetic bone mineral density (BMD) changes around a cementless short tapered-wedge stem and determine correlations between BMD changes and various clinical factors, including daily activity, after total hip arthroplasty (THA) with a short tapered-wedge stem. Methods. The study included 65 patients (65 joints) who underwent THA with a TriLock stem. At baseline, and 6, 12, and 24 months postoperatively, BMDs of the seven Gruen zones were evaluated using dual-energy X-ray absorptiometry. Correlations were determined between BMD changes and clinical factors, including the Harris hip score, body mass index, University of California at Los Angeles (UCLA) activity rating score, age at surgery, and initial lumbar BMD. Results. Minimal BMD changes were noted in the distal femur (Gruen zones 3, 4, and 5). However, significant BMD loss was noted in zone 7 at each time point. BMD loss was also noted in zone 1 at 6 and 12 months postoperatively, but BMD recovered after 18 months. Significant positive correlations were noted between BMD changes and the UCLA activity rating score in zones 1, 6, and 7. Additionally, negative correlations were noted between BMD changes and initial spine BMD in zones 2 and 3. Table legends. Table 1 Background of the patients. Table 2 Bone mineral density changes (%) at 6, 12, and 24 months postoperatively in the seven Gruen zones. Columns represent mean ± standard deviation. ※indicates P < 0.05 compared with baseline bone mineral density. Table 3 Correlations between periprosthetic bone mineral density changes and clinical factors (the Harris hip score, body mass index, University of California at Los Angeles activity rating score, age at surgery, and initial lumbar bone mineral density) in the seven Gruen zones at 24 months postoperatively. Correlation coefficients and P-values are presented. Boldface indicates P < 0.05. Conclusion. Periprosthetic BMD was maintained in the proximal femur, especially Gruen zone 1, with a short tapered stem. Daily activity may reflect improvements in periprosthetic bone quality after THA with a short tapered stem; however, this stem is not recommended in patients with low bone quality. To view tables, please contact authors directly

INTRODUCTION. Implantation of total hip arthroplasty (THA) components caused a significant alteration in stress environment. Several studies have reported that bone mineral density (BMD) decreases after THA, especially in the proximal femur. This phenomenon is explained as an adaptive remodeling response of bone tissue to a significant alteration in its stress environment. SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). The major change is an omission of the trochanteric wing, which enables a bone-sparing and may lead to changes of femoral stress distribution and rotational stability. The change of stress distribution in the femur could affect BMD after THA. In the present study, we constructed finite element (FE) models of femurs and stems before and at 1week after THA and analyzed equivalent stresses in the femur. In addition, we measured BMD in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress in the femur and to compare the results of the FE analyses with changes in BMD after THA. METHODS. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA stem or SL-PLUS standard stem formed the basis of this study. Eleven patients received SL-PLUS MIA stem and ten patients received SL-PLUS standard stem. The mean age of the patients at THA was 67 years (range: 48∼82). BMD was measured with DEXA at 1 week and 3, and 6 months after THA. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur of all patients were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analyzed in zones 1 to 7 and compared to the DEXA data. RESULTS. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA stem group and SL-PLUS standard stem group after THA. BMD was maintained at 6months after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. This means that BMD had decreased, especially in the proximal femur after THA. In zone 1, BMD decreased in SL-PLUS MIA stem group by 15%, while BMD was maintained in SL-PLUS standard stem. There was a significant difference in BMD percentage changes in zone 1 between SL-PLUS MIA stem group and SL-PLUS standard stem group at 6months after THA. DISCUSSION. The present study demonstrated that there was no significant difference in equivalent stress between SL-PLUS MIA stem group and SL-PLUS standard stem group after THA. In zone 1, BMD decreased in SL-PLUS MIA stem group by 15%, whereas BMD was maintained in SL-PLUS standard stem group. This result cannot be explained by our results of equivalent stress

Introduction. Resorptive bone remodeling secondary to stress shielding has been a concern associated with cementless total hip arthroplasty (THA). At present, various types of cementless implants are commercially available. The difference in femoral stem design may affect the degree of postoperative stress shielding. In the present study, we aimed to compare the difference in bone mineral density (BMD) change postoperatively in femurs after the use of 1 of the 3 types of cementless stems. Methods. Ninety hips of 90 patients who underwent primary cementless THA for the treatment of osteoarthritis were included in this study. A fit-and-fill type stem was used for 28 hips, a tapered-rectangular Zweymüller type stem was used for 32 hips, and a tapered-wedge type stem was used for 30 hips. The male/female ratio of the patients was 7/21 in the fit-and-fill type stem group, 6/26 in the tapered-rectangular Zweymüller type stem group, and 6/24 in the tapered-wedge type stem group. The mean age at surgery was 59.9 (39–80) in the fit-and-fill type stem group, 61.7 (48–84) in the tapered-rectangular Zweymüller type stem group and 59.6 (33–89) in the tapered-wedge type stem group. To assess BMD change after THA, we obtained dual-energy X-ray absorptiometry scans preoperatively and at 6, 12, 24, and 36 months postoperatively. Results. There were no differences in demographic data, such as gender, age at surgery, and body mass index, among the 3 groups (Table1). In terms of BMD change after THA, no differences were observed in Gruen zones 1–5 among the 3 groups during the 3-year follow-up. The BMD in Gruen zone 6 was maintained in the tapered-wedge type stem group, but decreased by 5% in the fit-and-fill type stem group and by 20% in the tapered-rectangular Zweymüller type stem group (p < 0.01). The BMD loss in Gruen zone 7 was observed in all stem types; however, the BMD loss at 36 months in the tapered-wedge type stem group (−15%) was significantly less than that of the other 2 groups (the fit-and-fill type stem group: −29%; the tapered-rectangular Zweymüller type stem group: −30%; p < 0.001 for both groups) (Figure). Discussion and Conclusion. A difference in postoperative BMD loss was observed among the 3 stem designs. This may be a result of the different fixation concept associated with each stem design. In the present study, we compared the postoperative BMD change after THA among a fit-and-fill type stem, a tapered-rectangular Zweymüller type stem, and a tapered-wedge type stem. BMD in the medial-proximal femur was maintained 3 years after THA in the group with the tapered-wedge type stem, which is fixed in a more proximal part of the femur compared to the other stems

INTRODUCTION. Loosening is a major cause for revision in uncemented hip prostheses due to insufficient primary stability. Primary stability after surgery is achieved through press-fit in an undersized cavity. Cavity preparation is performed either by extraction (removing bone) or compaction (crushing bone) broaching. Densification of trabecular bone has been shown to enhance primary stability in human femora; however, the effect of clinically used compaction and extraction broaches on human bone with varying bone mineral density (BMD) has not yet been quantified. The purpose of this study was to determine the influence of the broach design and BMD on the level of densification at the bone-cavity interface, stem seating, the bone-implant contact area and the press-fit achieved. METHODS. Paired human femora (m/f=11/12, age=60±18 y) were scanned with quantitative computed tomography (QCT, Philips Brilliance 16) before broaching, with the final broach, after its removal and after stem implantation. Compaction broaching (n=4) was compared in an in situ (cadaver) study against extraction broaching with blunt tooth types (n=3); in an ex situ (excised femora) study, compaction broaching was compared against extraction broaching with sharp tooth types (n=8 each). QCT data were resampled to voxel sizes of 1×1×1 mm (in situ) and 0.5×0.5×1 mm (ex situ). Mean trabecular BMD of the proximal femur was determined. The cavity volumes were segmented in the post-broach images (threshold: −250 mgHA/cm3, Avizo 9.2) and a volume of interest (VOI) of one-voxel thickness was added around the cavity to capture the interfacial bone. VOIs were transferred to the pre-broach image and bone densification was calculated within each VOI as the increase from pre- to post-broach image (MATLAB). Detailed surface data sets of broaches and stems were collected with a 3D laser-scanner (Creaform Handyscan 700) and aligned with the segmented components in the CT scans (Fig. 1). Stem seating was defined as the difference between the top edge of the stem coating and the final broach. Distance maps between the stem and cavity surface were generated to determine the bone-implant contact area and press-fit. All parameters were analysed between 5 mm distal to the coating and 1 cm distal to the lesser trochanter and analysed with related-samples Wilcoxon signed rank and Spearman's correlation tests (IBM SPSS Statistics 22). RESULTS. Trabecular BMD ranged from 81 to 221 mgHA/cm3. Densification was higher with compaction compared to sharp (p=0.034), but not blunt extraction broaching (p=1.000). Proximal bone-implant contact area, press-fit and stem seating did not differ between broaching methods. Bone-implant contact area and bone densification increased with trabecular BMD (rs=0.658, p=0.001 and rs=0.443, p=0.034), press-fit with stem seating (rs=0.746, p<0.001) and contact area with bone densification (rs=0.432, p=0.039). DISCUSSION. Sharp extraction broaching reduces densification at the bone-cavity interface, but does not affect the press-fit or contact area. Trabecular BMD was positively associated with contact area, and stem seating with press-fit. Future studies will aim to link these findings to primary stability and influence on periprosthetic fractures. For any figures or tables, please contact authors directly

The triple taper polished cemented stem (C-stem, DePuy) was developed to promote calcar loading, and reduce proximal femoral bone resorption and aseptic loosening. We aimed to evaluate the changes in peri-prosthetic bone mineral density using Dual Energy X-ray Absorbtiometry (DEXA) after total hip arthroplasty (THA) using the C-stem prosthesis. One hundred and three patients were recruited voluntarily through and single institution for THA. The prosthesis used was the triple-taper polished cemented C-Stem (De Puy, Warsaw, Indiana, USA). DEXA scans were performed pre- operatively, then at day for, three months, nine months, 18 months and 24 months post-operativley. Scans were analysed with specialised software (Lunar DPX) to measure bone mineral density (BMD) in all seven Gruen zones at each time interval. Changes in calcar BMD were also correlated with patient age, sex, surgical approach, pre-operative BMD and post-operative mobility to identify risk factors for periprosthetic bone resorption. One hundred and three patients underwent 103 primary THA over a five-year period (98 osteoarthritis; 5 AVN). No femoral components were loose at the two year review and none were revised. The most marked bone resorption occured in Gruen zones 1 and 7, and was best preserved in zone 5. BMD decreased rapidly in all zones in the first three months post-operatively, after which the rate of decline slowed substantially. BMD was better preserved medially (zones 6 and 5) than laterally (zones 2 and 3) at 24 months. There was delayed recovery of BMD in all zones except zones 4 and 5. High pre-operative T-scores (>2.0) in the spine, ipsilateral and contralateral femoral neck were associated with the higher post-operative BMD and less bone resorption at all time intervals in Gruen zone 7. Pre-operative osteopenia and osteoporosis were associated with low BMD and accelerated post-operative bone resorption in zone 7. Patients whose mobility rendered them housebound had lower post-operative BMD, and accelerated post-operative BMD loss in zone 7 when compared to non-housebound patients. Females had a lower post-operative BMD and greater loss of BMD in zone 7. Patient age and surgical approach did not effect post-operative BMD or rate of bone resorption in zone 7. The triple-taper femoral stem design did not show an increase in periprosthetic bone density at the proximal femur at two years post-operative. Calcar bone resorption is accelerated by low pre-operative BMD, poor post-operative mobility, and in females. Age and surgical approach do not have significant effects on calcar bone remodelling

Proximal tibial bone mineral density (BMD) has been shown to decrease following Total Knee Arthroplasty (TKA) by both dual-energy x-ray absorbtiometry (DEXA) and quantitative computed tomography (qCT)-assisted osteodensitometry. Little is known about changes in BMD following unicompartmental knee arthroplasty (UKA). Additionally, there are proposed differences in stress transmission between cemented metal and polyethylene (PE) components. We proposed two hypotheses. First, that proximal tibial BMD decreases following UKA. Second, that BMD loss would be greater below metal tibial components. We performed a prospective clinical trial of 50 consecutive UKAs in 49 patients performed by two surgeons at one institution. There were 25 mobile bearing Oxford and 25 fixed bearing Accuris arthroplasties, all were medial. BMD was assessed with qCT-assisted osteodensitometry scans prior to discharge and then at 1 and 2 years post surgery. Each CT slice was divided into medial and lateral halves and cortical and cancellous bone was analysed separately. The six 2mm slices immediately beneath the tibial implant were analysed using previously validated software to create a three-dimensional assessment of BMD. The lateral half was used as a control. There were a total of 30 females (60%), with an average age of 70 (49–84). One patient was lost to follow-up and another was unable to be analysed due to failure requiring revision before follow-up was complete. Preliminary results showed no significant change in BMD at either 1 or 2 years follow-up. There was no difference in BMD change between the mobile and fixed bearing prostheses, between the medial and lateral halves nor between cortical and cancellous bone. Final results will be presented at the AONZOA conference. This trial shows that UKA does not result in significant change to BMD at 2 years. The preservation of BMD may indicate that UKA is better at maintaining physiologic stress transfer than a TKA, which has been shown to be associated with a reduction in BMD

Bone mineral density (BMD) and bone mineral content (BMC) have not been previously assessed in unicompartmental knee replacement (UKR). We studied the early bone changes beneath the uncemented Oxford medial UKR. Our hypothesis was that this implant should decrease the shear stresses across the bone-implant interface and result in improved BMD and BMC beneath the tibial component. Using the Lunar iDXA and knee specific software we developed 7 regions of interest (ROI) in the proximal tibia and assessed 38 patients with an uncemented Oxford UKR at 2 years. We measured the replaced knee and contralateral unreplaced knee using the same ROI and compared the BMD and BMC. The initial precision study in 20 patients demonstrated high precision in all areas. There were 12 males and 16 females with an average age of 65.8 years (46–84 years). ROI 1 and 2 were beneath the tibial tray and had significantly less BMC (p=0.023 and 0.001) and BMD (p=0.012 and 0.002). ROI 3 was the lateral tibial plateau and this area also had significantly less BMC (p=0.007) and BMD (p=0.0001). ROI 4 and 5 immediately below the tibial keel had no significant change. These changes were independent of gender and age. These results were surprising in that the universal loss of BMC and BMD suggested that bone loading of the proximal tibia was not improved even after a UKR. The better BMD and BMC adjacent to the keel confirms other studies that show improved bone in-growth around keels and pegs in the uncemented tibial component. A prospective longitudinal study has been developed to compare BMD and BMC changes over time to see whether these changes are dynamic

The advantages of unicompartmental knee arthroplasty (UKA) include its bone preserving nature, lower relative cost and superior functional results. Some temporary pain has been reported clinically following this procedure. Could this be related to bone remodeling? A validated bone remodeling algorithm may have the answers…. A 3D geometry of an intact human cadaveric tibia was generated using CT images. An all poly unicompartmental implant geometry was positioned in an inlay and onlay configuration on the tibia and the post-operative models created. An adaptive bone remodeling algorithm was used with finite element modeling to predict the bone remodeling behavior surrounding the implant in both scenarios. Virtual DEXA images were generated from the model and bone mineral density (BMD) was measured in regions of interest in the AP and ML planes. BMD results were compared to clinical results. The bone remodelling algorithm predicted BMD growth in the proximal anterior regions of the tibia, with an inward tendency for both inlay and onlay models. Looking in the AP plane, a maximum of up to 7% BMD growth was predicted and in the ML plane this was as high as 16%. Minimal BMD loss was observed, which suggests minimal disturbance to the natural bone growth following UKA. Positron emission tomography (PET) scans showed active hot spots in the antero- medial regions of the tibia. These results were consistent with the finite element modeling results. Bone remodeling behavior was found to be sensitive to sizing and positioning of the implant. The adaptive bone remodeling algorithm predicted minimal BMD loss and some BMD growth in the anterior region of the tibia following UKA. This is consistent with patient complaint and PET scans

To achieve desirable outcomes in cementless total knee replacement (TKR), sufficient primary stability is essential. The primary stability inhibits excessive motions at the bone-implant interface, hence providing the necessary condition for osseointegration [1]. Primary stability for cementless TKR is provided by press-fit forces between the bone and implant. The press-fit forces depend on several factors including interference fit, friction between bone and implant surface, and the bone material properties. It is expected that bone mineral density (BMD) will affect the stability of cementless TKR [2]. However, the effect of BMD on the primary stability of cementless femoral knee component has not been investigated in vitro. Phantom calibrated CT-scans of 9 distal femora were obtained after the surgical cuts were made by an experienced surgeon. Since the press-fit forces of the femoral component mainly occur in the Anteroposterior (AP) direction, the BMD was measured in the anterior and posterior faces for a depth of 5 mm; this depth was based on stress distributions from a Finite Element Analysis of the same implant design. In addition, four strain gauges were connected to different locations on the implant's outer surface and implant strain measured throughout as an indication of underlying bone strain. A cementless Sigma CR femoral component (DePuy Synthes Joint Reconstruction, Leeds, UK) was then implanted using an MTS machine. In order to simulate a ‘normal’ bone condition, the implanted bone was preconditioned for one hour at a cyclic load of 250–1500 N, and a rate of 1 Hz. Finally, the implants were pushed-off from the bone in a high-flex position. Forces and displacements were recorded both during insertion and push-off tests. Strong correlations were found for insertion and push-off forces with BMD, R. 2. = 0.88 and R. 2. = 0.88, respectively (p < 0.001), so although implantation may be harder in patients with higher BMD, initial stability is also improved. A correlation was also found between final strain and push-off forces (R. 2. = 0.89, p < 0.01) and BMD also showed a strong reverse correlation with total bone relaxation (R. 2. = 0.76, p = 0.023). These results indicate that higher BMD induces higher bone strain, which can lead to improved fixation strength. There is no consensus on the best fixation method for the TKR but some surgeons prefer a cementless design for young and active patients. The results of our study showed that the primary stability of a cementless femoral knee component is directly correlated with the bone mineral density. Therefore, patient selection based on bone quality may increase the likelihood of good osseointegration and adequate long-term fixation for cementless femoral knee components

Vitamin D is vital for bone health because it assists in the absorption and utilisation of calcium. Vitamin D deficiency may predispose individuals to developing osteoporosis and subsequent osteoporotic fracture. There are various studies in elderly females with hip fractures correlating the low bone mineral density (BMD) with vitamin D levels. But very few studies have evaluated the influence on elderly males. Therefore this study was conducted. All male patients aged more than 50 years presenting to orthopaedic department, in JIPMER, Puducherry, with either fracture neck of femur or intertrochanteric fracture were included. Serum vitamin D level was assessed in them and BMD of both the hips was evaluated by DEXA scan. The vitamin D levels, T-scores, Z-scores were then analysed and correlated. Of the total 41 patients evaluated 21 (51%) had fracture neck of the femur and 20 (49%) patients had intertrochanteric fractures. We found that 11 (26.8%) patients had osteoporosis, 17 (41.5%) had osteopenia, and 13 (31.7%) had normal values. The mean value of total T-scores on fracture side was −1.55 and on no fracture side was −1.88. Among them 9 (22%) patients had vitamin D level <20 ng /mL, 15 (36%) had levels between 20ng–30ng/mL and 17 (41%) had >30ng/mL. Total T-score and Z-score on fracture side and no fracture side showed no correlation with vitamin D (p value >0.05) in these patients. We found significant osteoporosis in both neck and trochanteric regions on both fracture and no fracture sides, yet we had some patients with trochanteric fracture and some with neck fracture on only one side. In view of this other factors like mode of injury, velocity of injury, muscle wasting might have contributed significantly to the type of fracture and side involved. The BMD was found to be lower in patients with neck of femur fracture compared to intertrochanteric fracture, but no correlation was found between vitamin D and BMD scores at neck and trochanteric region. From this study it appears that there is no direct relationship between the vitamin D level and BMD in elderly males with hip fractures. It may emphasise that in male patients with hip fractures vitamin D may not have critical role in development of osteoporosis. The treatment of such patients with vitamin D supplements to prevent hip fractures is still debatable. However further studies in very large groups and controls may bring more light on this subject

Introduction. Fixation patterns of cementless stem were known as proximal or distal part. Distal fixation was seen in fully porous coated stem and stress shielding of the proximal femur was indicative. These phenomena did not lower the clinical results, but technical difficulties were more and more in revision surgery because of infection or dislocation. There was lot of reports that alendronate was effective for treatment of osteoporosis by induction of apoptosis in osteoclasts. We can expect alendronate to modify the bone quality around the stem after cementless THA. Objectives. We studied prospectively that quantitative computed tomography (QCT) measured bone mineral density around the stem between alendronate group and control. We tried to clarify that stress shielding after cementless THA can be prevented by use of alendronate or not. Materials and methods. From September 2011, 60 patients underwent total hip arthroplasty with cementless stems. Thirty patients took alendronate (35mg/week) after surgery (Group A) and remaining 30 patients were control (Group C). Between two groups, gender, age at surgery, diagnosis and body mass index were similar. Two types of stem were used as Zweimuller type or taperlock type. Just after THA, femoral shaft divided by Gruen zone measured bone mineral density (BMD) with QCT and forearm also measured BMD by DEXA. Following examination was performed at 6 months, 12 months and 24 months after surgery. Results. Gender of two groups was as follow: four males and twenty-six females in Group A and two males and twenty-eight females in Group C. The age at surgery was 67.6+7.9y in group A and 62.5+13.3y in group C. Zweimuller type was used for 18 patients and taperlock type was used for 12 patients in group A. Zweimuller type was used for 14 patients and taperlock type was used for 16 patients in group C. BMD of forearm were not different between two groups and it meant that bone quality and osteoporosis of groups was similar. On the other hands, femoral BMD of group A was higher than that of group C. Especially BMD of group C was relatively low in zone 1 and 7. Conclusion. Weekly use of alendronate (35mg) might be useful for preventing stress shielding after cementless THA

Pegs are often used in cementless total knee replacement (TKR) to improve fixation strength. Studies have demonstrated that interference fit, surface properties, bone mineral density (BMD) and viscoelasticity affect the performance of press-fit designs. These parameters also affect the insertion force and the bone damage occurring during insertion. We aimed to quantify the effect of the aforementioned parameters on the short-term fixation strength of cementless pegs. 6 mm holes were drilled in twenty-four human femora. BMD was measured using calibrated CT-scans, and randomly assigned to samples. Pegs were produced to investigate the effect of interference fit (diameters 6.5 and 7.6 mm), surface treatment (smooth and rough- porous-coating [friction coefficient: 1.4]) and bone relaxation (relaxation time 0 and 30 min) and interactions were studied using a DOE method. Two additional rough surfaced peg designs (diameters 6.2 and 7.3 mm) were included to scrutinize interference. Further, a peg based on the LCS Porocoat® (DePuy Synthes Joint Reconstruction, Leeds, UK) was added as a clinical baseline. In total seven designs were used (n = 10 for all groups). Pegs were inserted and extracted using an MTS machine (Figure 1), while recording force and displacement. Bone damage was defined as the difference between the cross-sectional hole area prior to and after the test. BMD and interference fit were significant factors for insertion force. BMD had a significant positive correlation with pull-out force and subsequent analyses were therefore normalised for BMD. . Pull-out force increased significantly with interference for both surface coatings at time 0 (p < 0.05). However, after 30 minutes the effect remained significant for rough pegs only (p < 0.05-Figure 2A). Pull-out force reduced significantly with roughness for both peg diameters at time 0 (p < 0.001). However, after 30 minutes the effect remained significant for small pegs only (p < 0.05-Figure 2A). The time dependant interaction was only significant for smooth pegs in both diameters (p < 0.05-Figure 2A). Additionally, the pull-out force increased with diameter in a non-linear manner for the rough pegs (Figure 2B). The two surface treatments were not significantly different to the clinical comparator. Interference fit was the only significant factor for bone damage. BMD was significant for insertion and pull-out forces, reinforcing the need to account for this factor in biomechanical studies and clinical practice. This study also highlights the importance of time in studying bone interactions, with surface treatment and interference showing different interaction effects with relaxation time. Although smooth pegs initially have a higher pull-out force, this effect reduces over time whereas the pullout force for rough pegs is maintained. Smooth pegs also show time sensitivity in relation to interference and the benefit of increased interference reduces over time, whereas it is maintained in rough pegs. This may be explained by different damage (compressive and abrasive) mechanisms associated with different surface treatments. In conclusion, BMD and interference fit are significant factors for initial fixation. Bone relaxation plays an important role as it reduces the initial differences between groups. Therefore, these findings should be strongly considered in the design development of cementless TKR

Introduction. Trabecular Titanium™ is a highly porous biomaterial with a regular hexagonal cell structure, which has shown excellent mechanical properties. Several in vitro studies reported promising data on its osteoinductive and osteoconductive properties. Furthermore, it has demonstrated in vivo to enhance bone in-growth. Aim of this multicentre prospective study was to assess Trabecular Titanium™ osseointegration by measuring change in bone mineral density (BMD) around a cementless DELTA-TT cup with dual-emission X-ray absorptiometry (DXA). Methods. 89 patients (91 hips) underwent primary THA with DELTA-TT cups (Lima Corporate) between 2009 and 2010. There were 46 (52%) men and 43 (48%) women, with a median (IQR) age of 67 (57–70) years and a median (IQR) BMI of 26 (24–29) kg/m. 2. Right side and left side were affected in 44 (48%) and 47 (52%) cases, respectively. Underlying pathology was primary osteoarthritis in 80 (88%) cases, osteonecrosis in 5 (6%), post-traumatic osteoarthritis in 3 (3%), developmental dysplasia of the hip in 2 (2%) and oligoarthritis in 1 (1%). BMD was determined by DXA using DeLee and Charnley 3 Regions of Interest (ROI) at 7 days, 3, 6, 12 and 24 months. Clinical evaluation (Harris Hip Score, HHS), patient health status survey (SF-36) and radiographic assessment were performed preoperatively and at the same time-points. Data were analyzed using non-parametric tests (Mann-Whitney, Wilcoxon signed-rank) and a p < 0.05 as threshold for statistical significance. Results. Excellent results were observed in terms of pain relief and functional recovery. Median (IQR) HHS improved from 48 (39–62) before surgery, to 99 (96–100) at 24 months, with a statistical significant increase of 96% (p < 0.05, Wilcoxon signed-rank). Median (IQR) SF-36 improved from 49 (37–62) preoperatively to 86 (79–92) at 24 months, with a statistical significant increase of 95% (p < 0.05, Wilcoxon signed-rank), indicating a considerable improvement in patients' quality of life. After an initial decrease of BMD values from baseline at 7 days (median [IQR] ROI I: 1.44 [1.21–1.67]; ROI II: 1.23 [0.99–1.49]; ROI III: 1.11 [0.85–1.48] g/cm. 2. ) to 6 months (ROI I: 1.27 [1.08–1.52]; ROI II: 1.14 [0.89–1.37]; ROI III: 1.05 [0.73–1.35] g/cm. 2. ), BMD slightly increased in ROI I, the most loaded area, and stabilized in ROI III. BMD in ROI II increased after 12 months and stabilized at 24 months (ROI I: 1.30 [1.11–1.55]; ROI II: 1.12 [0.96–1.36]; ROI III: 1.04 [0.80–1.25] g/cm. 2. ). Radiographic analysis showed evident signs of bone remodeling and osseointegration, with presence of supero-lateral and infero-medial bone buttress and of radial trabeculae perpendicular to the cup surface in ROI I/II. No radiolucent lines, loosening or osteolysis were observed. All cups were stable and no revision was carried out. Conclusion. BMD patterns and radiographic evaluation showed signs of an effective osseointegration around DELTA-TT cups at 24 months. Although clinical outcomes, functional recovery and stability are very satisfactory, longer follow-ups are necessary to assess survivorship

The purpose of this study was to compare the clinical, radiographic, and DEXA results of Epoch® Femoral Component for primary THA with other non-cemented femoral components. The Epoch and Epoch 14+ (Zimmer, Warsaw, IN) Composite Femoral Components were studied in conjunction with the VerSys® Fiber Metal Taper, Fiber Metal Mid coat and Beaded Fullcoat Femoral Components (Zimmer, Warsaw, IN). All patients were randomized into one of five component groups and followed prospectively. All patients across the five groups were matched with respect to demographics and body mass index (BMI) (Table 1). Diagnoses were evenly distributed across all study groups. There was no significant change in BMD at 5-years when compared to the baseline (6 month) DEXA measurements for all component groups except for the Beaded Fullcoat component subset which had significant decreases in BMD in proximal zones 1, 6 and 7, The Fiber Metal Taper showed similar decreases in BMD in zones 1 and 7, and the Epoch Component had a significant decrease in BMD in zone 7 only. Additionally, our DEXA findings complement and support the subjective radiographic interpretations performed for this study cohort. The results from this prospective, randomized controlled clinical trial showed that the Epoch Composite Femoral Component for primary THA can achieve results equal to standard alloy components of varying design. Based on these early results, the Epoch and Epoch 14+ Femoral Components for primary THA are justified for continuance of further prospective study

Introduction. Trabecular Titanium is a biomaterial characterized by a regular three-dimensional hexagonal cell structure imitating trabecular bone morphology. Components are built via Electron Beam Melting technology in aone- step additive manufacturing process. This biomaterial combines the proven mechanical properties of Titanium with the elastic modulus provided by its cellular solid structure (Regis 2015 MRS Bulletin). Several in vitro studies reported promising outcomes on its osteoinductive and osteoconductive properties: Trabecular Titanium showed to significantly affect osteoblast attachment and proliferation while inhibiting osteoclastogenesis (Gastaldi 2010 J Biomed Mater Res A, Sollazzo 2011 ISRN Mater Sci); human adipose stem cells were able to adhere, proliferate and differentiate into an osteoblast-like phenotype in absence of osteogenic factors (Benazzo 2014 J Biomed Mater Res A). Furthermore, in vivo histological and histomorphometric analysis in a sheep model indicated that it provided bone in-growth in cancellous (+68%) and cortical bone (+87%) (Devine 2012 JBJS). A multicentre prospective study was performed to assess mid-term outcomes of acetabular cups in Trabecular Titanium after Total Hip Arthroplasty (THA). Methods. 89 patients (91 hips) underwent primary cementless THA. There were 46 (52%) men and 43 (48%) women, with a median (IQR) age and BMI of 67 (57–70) years and 26 (24–29) kg/m2, respectively. Diagnosis was mostly primary osteoarthritis in 80 (88%) cases. Radiographic and clinical evaluations (Harris Hip Score [HHS], SF-36) were performed preoperatively and at 7 days, 3, 6, 12, 24 and 60 months. Bone Mineral Density (BMD) was determined by dual-emission X-ray absorptiometry (DEXA) according to DeLee &Charnley 3 Regions of Interest (ROI) postoperatively at the same time-points using as baseline the measureat 1 week. Statistical analysis was carried out using Wilcoxon test. Results. Median (IQR) HHS and SF-36 improved significantly from 48 (39–61) and 49 (37–62) preoperatively to 99 (96–100) and 76 (60–85) at 60 mo. (p≤0.0001). Radiographic analysis showed evident signs of bone remodelling and biological fixation, with presence of superolateral and inferomedial bone buttress, and radial trabeculae in ROI I/II. All cups resulted radiographically stable without any radiolucent lines. The macro-porous structure of this biomaterial generates a high coefficient of friction (Marin 2012 Hip Int), promoting a firm mechanical interlocking at the implant-bone interface which could be already observed in the operating room. BMD initially declined from baseline at 7 days to 6 months. Then, BMD slightly increased or stabilized in all ROIs up to 24 months, while showing evidence of partial decline over time with increasing patient' age at 60 months, although without any clinical significance in terms of patients health status or implant stability. Statistical significant correlations in terms of bone remodeling were observed between groups of patients on the basis of gender and age (p≤0.05). No revision or implant failure was reported. Conclusions. All patients reported significant improvements in quality of life, pain relief and functional recovery. Radiographic evaluation confirmed good implant stability at 60 months. These outcomes corroborate the evidence reported on these cups by orthopaedic registries and literature (Perticarini 2015 BMC Musculoskelet Disord; Bistolfi 2014 Min Ortop)