Total knee arthroplasty (TKA) is known to lead to a reduction in periprosthetic bone mineral density (BMD). In theory, this may lead to migration, instability and aseptic loosening of the prosthetic components. Bisphosphonates inhibit bone resorption and may reduce this loss in BMD. We hypothesised that treatment with bisphosphonates and calcium would lead to improved BMD and clinical outcomes compared with treatment with calcium supplementation alone following TKA. A total of 26 patients, (nine male and 17 female, mean age 67 years) were prospectively randomised into two study groups: alendronate and calcium (bisphosphonate group, n = 14) or calcium only (control group, n = 12). Dual energy X-ray absorptiometry (DEXA) measurements were performed post-operatively, and at three months, six months, one, two, four, and seven years post-operatively.

Mean femoral metaphyseal BMD was significantly higher in the bisphosphonate group compared with controls, up to four years following surgery in some areas of the femur (p = 0.045). BMD was observed to increase in the lateral tibial metaphysis in the bisphosphonate group until seven years (p = 0.002), and was significantly higher than that observed in the control group throughout (p = 0.024). There were no significant differences between the groups in the central femoral metaphyseal, tibial medial metaphyseal or diaphyseal regions of interest (ROI) of either the femur or tibia.

Bisphosphonate treatment after TKA may be of benefit for patients with poor bone quality. However, further studies with a larger number of patients are necessary to assess whether this is clinically beneficial.

Cite this article: Bone Joint J 2015;97-B:337–45.

Aims. The aim of this study was to compare the pattern of initial fixation and changes in periprosthetic bone mineral density (BMD) between patients who underwent total hip arthroplasty (THA) using a traditional fully hydroxyapatite (HA)-coated stem (T-HA group) and those with a newly introduced fully HA-coated stem (N-HA group). Methods. The study included 36 patients with T-HA stems and 30 with N-HA stems. Dual-energy X-ray absorptiometry was used to measure the change in periprosthetic BMD, one and two years postoperatively. The 3D contact between the stem and femoral cortical bone was evaluated using a density-mapping system, and clinical assessment, including patient-reported outcome measurements, was recorded. Results. There were significantly larger contact areas in Gruen zones 3, 5, and 6 in the N-HA group than in the T-HA group. At two years postoperatively, there was a significant decrease in BMD around the proximal-medial femur (zone 6) in the N-HA group and a significant increase in the T-HA group. BMD changes in both groups correlated with BMI or preoperative lumbar BMD rather than with the extent of contact with the femoral cortical bone. Conclusion. The N-HA-coated stem showed a significantly larger contact area, indicating a distal fixation pattern, compared with the traditional fully HA-coated stem. The T-HA-coated stem showed better preservation of periprosthetic BMD, two years postoperatively. Surgeons should consider these patterns of fixation and differences in BMD when selecting fully HA-coated stems for THA, to improve the long-term outcomes. Cite this article: Bone Joint J 2024;106-B(6):548–554

Aims. This study was designed to develop a model for predicting bone mineral density (BMD) loss of the femur after total hip arthroplasty (THA) using artificial intelligence (AI), and to identify factors that influence the prediction. Additionally, we virtually examined the efficacy of administration of bisphosphonate for cases with severe BMD loss based on the predictive model. Methods. The study included 538 joints that underwent primary THA. The patients were divided into groups using unsupervised time series clustering for five-year BMD loss of Gruen zone 7 postoperatively, and a machine-learning model to predict the BMD loss was developed. Additionally, the predictor for BMD loss was extracted using SHapley Additive exPlanations (SHAP). The patient-specific efficacy of bisphosphonate, which is the most important categorical predictor for BMD loss, was examined by calculating the change in predictive probability when hypothetically switching between the inclusion and exclusion of bisphosphonate. Results. Time series clustering allowed us to divide the patients into two groups, and the predictive factors were identified including patient- and operation-related factors. The area under the receiver operating characteristic (ROC) curve (AUC) for the BMD loss prediction averaged 0.734. Virtual administration of bisphosphonate showed on average 14% efficacy in preventing BMD loss of zone 7. Additionally, stem types and preoperative triglyceride (TG), creatinine (Cr), estimated glomerular filtration rate (eGFR), and creatine kinase (CK) showed significant association with the estimated patient-specific efficacy of bisphosphonate. Conclusion. Periprosthetic BMD loss after THA is predictable based on patient- and operation-related factors, and optimal prescription of bisphosphonate based on the prediction may prevent BMD loss. Cite this article: Bone Joint Res 2024;13(4):184–192

Introduction. Several short femoral stems have been introduced in primary total hip arthroplasty, supposedly in order to save proximal bone stock. We intended to analyse primary stability, changes in periprosthetic bone mineral density (BMD), and clinical outcome after insertion of the uncemented collum femoris preserving (CFP)-femoral device. Methods. A prospective cohort study on 30 patients scheduled for receiving the CFP-stem combined with an uncemented cup was carried out. Stem migration was analysed by radiostereometry (RSA). Preoperative total hip BMD and postoperative periprosthetic BMD in Gruen zones 1–7 was investigated by DXA, and the Harris hips score (HHS) was determined. The patients were followed up to 12 months. Results. 2 patients were intraoperatively excluded because their proximal femur was found to be unsuitable for insertion of the studied implant, 1 patient was later revised due to a deep infection. This left 27 patients for final analysis. RSA showed that only very little migration of the implant occurred, with the largest amplitude found in rotation around the y-axis (1.8°, SD 0.6, after 12 mths), representing minimal stem retroversion. DXA after 12 mths demonstrated substantial BMD loss in Gruen zones 7 (−30.8%), 6 (−19.1%) and 2 (−13.3%, p-values for all described changes <0.001 when comparing with baseline BMD determined immediately postoperatively). There was a moderate correlation of low preoperative total hip BMD with a higher amount of bone loss in Gruen zones 2 (Pearson correlation coefficient r = 0.6, p = 0.001), 6 (r = 0.5, p = 0.005) and 7 (r = 0.6, p = 0.003). In contrast, we found no correlation of periprosthetic bone loss in any of the Gruen zones 1–7 with logarithmically transformed maximal total point translation (MTPT) of the stem (p > 0.05 for all regions), neither after 3 nor after 12 mths. The mean HHS increased from 49 (SD 15) preoperatively to 99 (SD 2) after 12 mths. Interpretation. Based on these short-term data, we conclude that i) the studied implant seems to be stable within the first year, ii) substantial loss in periprosthetic BMD - with a predominance in the calcar region - occurs, iii) low preoperative total hip BMD predisposes towards greater loss of periprosthetic BMD after 12 months, iv) postoperative loss in periprosthetic BMD does not correlate with increased stem migration. Clinical results are excellent so far. Continuing follow-up will reveal whether this novel stem remains stable in the medium and long term, and whether the loss in BMD in the regions mentioned above can be recovered with time or whether it continues

Introduction: Continous periprosthetic bone loss after uncemented THA may lead to proximal femoral atrophy and increase the risk for aseptic loosening or peripros-thetic femoral fracture in the long-term. Little is known about the extent and the pattern of bone remodeling around stable, straight uncemented stems after 15 years. Patients and Methods: In a prospective longitudinal study, bone mineral density (BMD) was measured in 131 patients with 146 stable, uncemented, double- tapered, grit- blasted stems (CLS Spotorno, Zimmer, Warsaw, USA) using dual- energy x-ray absorptiometry (DEXA) after a mean of 12 years (range:10–15, t1) postoperatively. Patients were followed with radiographs and Harris hip scores (HHS), and a second and third DEXA were performed at a mean follow-up of 17 years (range: 15–20, t2) and 22 years (range: 20–25, t3) using the identical protocol. Results: We obtained a complete prospective set of data of three consecutive DEXA measurements for 37 hips (32 patients, 14 male, 18 female). In all cases regular bone ongrowth did occur and on radiographic evaluation there were no signs of loosening and no significant change in periprosthetic bone formation. There was no case of severe bone loss and no case of diaphyseal cortical hypertrophy. We analyzed the differences in overall femoral BMD (netavg) and in BMD in zones 1–7 according Gruen. There was no significant change in overall netavg BMD for both male and female patients (p> 0,05) comparing t1 and t3. We found a significant change in periprosthetic BMD in zone 7 (−6,62%, p< 0,05) in male patients and in zones 1, 6 and 7 (−8,7%/−5,1%/−14,2%, p< 0,01/0,05/0,01) in female patients. Discussion and Conclusion: The results of our study suggest that there are no clinically relevant changes in overall periprosthetic BMD around stable, uncemented straight stems in the long- term. However, continuous bone remodeling with slow but steady proximal bone loss occurs, predominantly in female patients. Once osseous integration is observed, stress shielding remains moderate and changes in periprosthetic BMD are limited to the metaphyseal region

The pattern and magnitude of pelvic periprosthetic bone loss around cementless metal-backed acetabular implants have previously been described. The pattern of periprosthetic BMD change around cemented all-polyethylene acetabular implants is unreported. The aims of this study were to determine the precision of pelvic BMD measurements around the Charnley cup and to examine the longitudinal pattern of BMD change over the first 2 years after surgery. 19 subjects who had previously received a Charnley cup for osteoarthritis underwent duplicate measurements of pelvic BMD after repositioning using an Hologic QDR 4500A densitometer. Scan analysis was carried out using a 4-region of interest model according to a protocol previously described. In-vivo precision was expressed as coefficient of variation (CV%) for each region of interest. The precision of pelvic periprosthetic BMD measurements were 7.7%, 9.8%, 10.8%, and 9.9% for regions 1 to 4, respectively. Longitudinal BMD changes were measured over a 2 year period in 32 patients (mean age 74 years; 22 women) undergoing cemented THA for unilateral osteoarthritis (17 right-sided). Transient decreases in BMD were observed in regions 2 and 3 (behind the dome of the implant) at 3 months (−9.0% and −13.2%, respectively; P< 0.05) and at 1 year (−8.1% and −9.3%; P< 0.05). By 2 years there had been some recovery in bone mass (BMD−6.9% and −2.6% respectively). No significant changes in BMD for regions 1 and 4 (located at the rim of the implant) were found. The precision of pelvic periprosthetic BMD measurements for the cemented Charnley cup are poorer than those we have previously reported for cementless cups and may be due, in part, to cement artifact. The pattern of BMD change observed for the Charnley implant suggests that load transfer between the implant and the pelvis occurs principally at the implant rim. The magnitude of bone loss is similar to that we have previously reported for cementless metal-backed acetabular implants

Objectives. Our primary aim was to describe migration of the Exeter stem with a 32 mm head on highly crosslinked polyethylene and whether this is influenced by age. Our secondary aims were to assess functional outcome, satisfaction, activity, and bone mineral density (BMD) according to age. Patients and Methods. A prospective cohort study was conducted. Patients were recruited into three age groups: less than 65 years (n = 65), 65 to 74 years (n = 68), and 75 years and older (n = 67). There were 200 patients enrolled in the study, of whom 115 were female and 85 were male, with a mean age of 69.9 years (sd 9.5, 42 to 92). They were assessed preoperatively, and at three, 12 and, 24 months postoperatively. Stem migration was assessed using Einzel-Bild-Röntgen-Analyse (EBRA). Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), EuroQol-5 domains questionnaire (EQ-5D), short form-36 questionnaire (SF-36,) and patient satisfaction were used to assess outcome. The Lower Extremity Activity Scale (LEAS), Timed Up and Go (TUG) test, and activPAL monitor (energy expelled, time lying/standing/walking and step count) were used to assess activity. The BMD was assessed in Gruen and Charnley zones. Results. Mean varus/valgus tilt was -0.77⁰ and axial subsidence was -1.20 mm. No significant difference was observed between age groups (p ⩾ 0.07). There was no difference according to age group for postoperative WOMAC (p ⩾ 0.11), HHS (p ⩾ 0.06), HOOS (p ⩾ 0.46), EQ-5D (p ⩾ 0.38), patient satisfaction (p ⩾ 0.05), or activPAL (p ⩾ 0.06). Patients 75 years and older had a worse SF-36 physical function (p = 0.01) and physical role (p = 0.03), LEAS score (p < 0.001), a shorter TUG (p = 0.01), and a lower BMD in Charnley zone 1 (p = 0.02). Conclusion. Exeter stem migration is within normal limits and is not influenced by age group. Functional outcome, patient satisfaction, activity level, and periprosthetic BMD are similar across all age groups. Cite this article: N. D. Clement, M. Bardgett, K. Merrie, S. Furtado, R. Bowman, D. J. Langton, D. J. Deehan, J. Holland. Cemented Exeter total hip arthroplasty with a 32 mm head on highly crosslinked polyethylene: Does age influence functional outcome, satisfaction, activity, stem migration, and periprosthetic bone mineral density? Bone Joint Res 2019;8:275–287. DOI: 10.1302/2046-3758.86.BJR-2018-0300.R1

Aims. Dual mobility (DM) implants have been shown to reduce the dislocation rate after total hip arthroplasty (THA), but there remain concerns about the use of cobalt chrome liners inserted into titanium shells. The aim of this study was to assess the clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) at mid-term follow-up in young, active patients receiving a modular DM THA. Methods. This was a prospective study involving patients aged < 65 years, with a BMI of < 35 kg/m. 2. , and University of California, Los Angeles activity score of > 6 who underwent primary THA with a modular cobalt chrome acetabular liner, highly cross-linked polyethylene mobile bearing, and a cementless titanium femoral stem. Patient-reported outcome measures, whole blood metal ion levels (μg/l), and periprosthetic femoral BMD were measured at baseline and at one, two, and five years postoperatively. The results two years postoperatively for this cohort have been previously reported. Results. A total of 43 patients were enrolled. At minimum follow-up of five years, 23 (53.4%) returned for clinical and radiological review, 25 (58.1%) had metal ion analysis performed, 19 (44.2%) underwent dual energy x-ray absorptiometry scans, and 25 (58%) completed a pain-drawing questionnaire. The mean modified Harris Hip Scores improved significantly from 54.8 (SD 19) preoperatively to 93.08 (SD 10.5) five years postoperatively (p < 0.001). One patient was revised for aseptic acetabular loosening. The mean cobalt levels increased from 0.065 μg/l (SD 0.03) to 0.08 (SD 0.05) and the mean titanium levels increased from 0.35 (SD 0.13) to 0.78 (SD 0.29). The femoral BMD ratio decreased in Gruen Zone 1 (91.9%) at five years postoperatively compared with the baseline scores at six weeks potoperatively. The femoral BMD ratio was maintained in Gruen zones 2 to 7. Conclusion. The use of a modular DM component and a cementless, tapered femoral stem shows excellent mid-term survivorship with minimal concerns for corrosion and metal ion release in a cohort of young, active patients undergoing primary THA. Cite this article: Bone Joint J 2021;103-B(7 Supple B):73–77

This study aimed to A) establish a protocol for measuring periprosthetic bone mineral density (BMD) of the proximal humerus following implant arthroplasty, and B) compare the differences in the periprosthetic BMD values 4–9 years after surface replacement and stemmed arthroplasties of the proximal humerus. The study design was of retrospective independent samples cohorts, of patients who had received a proximal humeral arthroplasty between January 1992 and December 1996 in a tertiary referral shoulder unit of a UK hospital. The exclusion criteria were A) patient unavailable for study, B) patient refusal, C) inadequate information of dependent and independent variables, or D) obvious measurement errors. All available patients underwent DEXA scanning of the proximal humerus using a Lunar DPXL scanner fitted with Orthopaedic Hip software version 1.3. Replicable patient positioning with a special jig was used. On a predetermined format of Gruen equivalent zones and sub-zones, BMD values in gm/cm. 2. were plotted. Cortical thickness on plain radiographs was recorded for each zone. Femoral neck DEXA scan was performed to obtain a proportionate value of BMD of the proximal humerus, in order to eliminate the effect of confounding variables. Confounding variables accounted for were age, gender, height, weight, activity level, indication for surgery, duration of implantation, dominance, type of arthroplasty (hemi or total) and use of cemented or uncemented stemmed implants. Statistical analysis was performed using Microsoft excel as well as SPSS software. Initially, 58 shoulders in 52 patients were recruited. 6 patients declined to participate for ill health, 6 had moved out of the area and 8 did not attend or reply. Of the remaining 31 shoulders in 25 patients, 2 patients had an obviously erroneous DEXA reading. 29 shoulders in 23 patients were finally analysed, which included 10 male and 19 female shoulders. Average age was 67.5 years and average time since surgery was 6 years 2 months. Indications for surgery were RA in 14, OA in 8 and other reasons in 7. Of 29 shoulders, 20 received a total replacement, 9 a hemiarthroplasty. The inevitable obliquity of the image caused some difficulties in maintaining accuracy and difficulties were observed due to limitation of the software to measure thin cortices and to distinguish between the cement and bone. There was no significant correlation between gross cortical thickness and BMD values, and the average periprosthetic BMD was 0.54 g/cm. 2. Surface replacement implants were associated with relative preservation of proximal medial cortex and higher BMD values in this region. BMD values were consistently higher at the level of stem tip for the stemmed implants. No such phenomenon was observed for the surface replacement prostheses. Hemiarthroplasty was associated with relatively higher BMD values in the proximal medial cortical region than total arthroplasty

Aims. Modular dual mobility (DM) prostheses in which a cobalt-chromium liner is inserted into a titanium acetabular shell (vs a monoblock acetabular component) have the advantage of allowing supplementary screw fixation, but the potential for corrosion between the liner and acetabulum has raised concerns. While DM prostheses have shown improved stability in patients deemed ‘high-risk’ for dislocation undergoing total hip arthroplasty (THA), their performance in young, active patients has not been reported. This study’s purpose was to assess clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) in young, active patients receiving a modular DM acetabulum and recently introduced titanium, proximally coated, tapered femoral stem design. Patients and Methods. This was a prospective study of patients between 18 and 65 years of age, with a body mass index (BMI) < 35 kg/m. 2. and University of California at Los Angeles (UCLA) activity score > 6, who received a modular cobalt-chromium acetabular liner, highly crosslinked polyethylene mobile bearing, and cementless titanium femoral stem for their primary THA. Patients with a history of renal disease and metal hardware elsewhere in the body were excluded. A total of 43 patients (30 male, 13 female; mean age 52.6 years (. sd. 6.5)) were enrolled. All patients had a minimum of two years’ clinical follow-up. Patient-reported outcome measures, whole blood metal ion levels (ug/l), and periprosthetic femoral BMD were measured at baseline, as well as at one and two years postoperatively. Power analysis indicated 40 patients necessary to demonstrate a five-fold increase in cobalt levels from baseline (alpha = 0.05, beta = 0.80). A mixed model with repeated measures was used for statistical analysis. Results. Mean Harris Hip Scores improved from 54.1 (. sd. 20.5) to 91.2 (. sd. 10.8) at two years postoperatively (p < 0.001). All patients had radiologically well-fixed components, no patients experienced any instability, and no patients required any further intervention. Mean cobalt levels increased from 0.065 ug/l (. sd. 0.03) preoperatively to 0.30 ug/l (. sd. 0.51) at one year postoperatively (p = 0.01) but decreased at two years postoperatively to 0.16 ug/l (. sd. 0.23; p = 0.2). Four patients (9.3%) had a cobalt level outside the reference range (0.03 ug/l to 0.29 ug/l) at two years postoperatively, with values from 0.32 ug/l to 0.94 ug/l. The mean femoral BMD ratio was maintained in Gruen zones 2 to 7 at both one and two years postoperatively using this stem design. At two years postoperatively, mean BMD in the medial calcar was 101.5% of the baseline value. Conclusion. Use of a modular DM prosthesis and cementless, tapered femoral stem has shown encouraging results in young, active patients undergoing primary THA. Elevation in mean cobalt levels and the presence of four patients outside the reference range at two years postoperatively demonstrates the necessity of continued surveillance in this cohort. Cite this article: Bone Joint J 2019;101-B:365–371

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

Purpose. The study aim was to assess how the periprosthetic bone density of the MiniHip™ changed in the course of the first year. Is there a correlation between the decrease in bone density with CCD angle or stem size? Are there other variables influencing the changes in bone density?. Material and Methods. 62 patients aged 25–78 years (34 women, 28 men) were implanted with a MiniHip total hip replacement during 2011 and 2012 through an anterolateral minimally invasive (ALMI) approach. Pre-operative diagnosis was osteoarthritis in 49 patients, dysplasia in 7, femoral necrosis in 4 and femoral neck fracture in 2 cases. As a primary variable the periprosthetic bone mineral density (BMD) was measured postoperatively within the first 2 weeks as a baseline measurement. Follow-up measurements were performed at 3, 6 and 12 months postoperatively. Statistical analysis was conducted to show any differences. Results. There is an initial post-operative loss of BMD in the first 3 months due to surgery and inactivity, with a significant decrease in the periprosthetic BMD proximally in Gruen Zones 1 (10.05%), 2 (12.37%) and 7 (10.05%) and distally in Gruen Zone 4 (6.9%). The density in the remaining Gruen regions also decreased but was not significant. In the following 3 months, the decrease in this Gruen regions continues without being significant. But after 6 months the bone mineral density shows a regeneration. At 12 months compared with the 6 months results there is an increase in BMD in Gruen Zones 1 (5.09%) and 7 (2.82%), also an increase in Gruen Zone 3 (1.75%) and 4 (1.78%) [Fig. 1]. A significant correlation between stem size and proximally bone loss in Gruen zones 1 & 7 was seen. In Gruen zone 1, there is also a correlation between bone loss and femoral neck angle, whereas this correlation was not significant in Gruen zone 7, but showing the same tendency. The analysis of covariables showed no dependencies of the results to sex, diagnosis or bearing surfaces. Conclusion. The MiniHip shows a loss of bone mineral density immediately post-operatively. After the initial decrease there was an increase especially in the proximal Gruen zones 1 and 7. Compared to other cementless short stems there was a lower bone density decrease [Fig. 2]. MiniHip™ loads the proximal femur in a more physiological way, which may preserve more bone in zones 1 and 7

We measured bone mineral density (BMD) in the proximal femur by dual-energy X-ray absorptiometry (DEXA) in 20 patients after cemented total hip arthroplasty over a period of one year. We found a statistically significant reduction in periprosthetic BMD after six months on the medial side and on the lateral side adjacent to the mid and distal thirds of the prosthesis. At one year after operation there was a mean 6.7% reduction in BMD in the region of the calcar and a mean 5.3% increase in BMD in the femoral shaft distal to the tip of the implant. These changes reflect a pattern of reduced stress in the proximal femur and increased stress around the tip of the prosthesis. They support current concepts of bone remodelling in the proximal femur in response to prosthetic implantation

We investigated prospectively the bone mineral density (BMD) of the proximal femur after implantation of a tapered rectangular cementless stem in 100 patients with a mean age of 60 years (16 to 87). It was determined using dual energy x-ray absorptiometry, performed one week after surgery and then every six months until the end-point of five years. The BMD increased significantly in Gruen zones 2, 4 and 5 by 11%, 3% and 11% respectively, and decreased significantly in Gruen zones 1, 6 and 7 by 3%, 6% and 14% respectively, over the five-year period. The net mean BMD did not change over this time period. The changes in the BMD were not confined to the first 12 months after surgery. This investigation revealed no change in the overall periprosthetic BMD, but demonstrated a regional redistribution of bone mass from the proximal to distal zones

We investigated the effect of the Birmingham hip resurfacing (BHR) arthroplasty on the bone mineral density (BMD) of the femur. A comparative study was carried out on 26 hips in 25 patients. Group A consisted of 13 patients (13 hips) who had undergone resurfacing hip arthroplasty with the BHR system and group B of 12 patients (13 hips) who had had cementless total hip arthroplasty with a proximal circumferential plasma-spray titanium-coated anatomic Ti6A14V stem. Patients were matched for gender, state of disease and age at the time of surgery. The periprosthetic BMD of the femur was measured using dual-energy x-ray absorptiomentry of the Gruen zones at two years in patients in groups A and B. The median values of the BMD in zones 1 and 7 were 99% and 111%, respectively. The post-operative loss of the BMD in the proximal femur was significantly greater in group B than in group A. These findings show that the BHR system preserves the bone stock of the proximal femur after surgery

Aim: Stress-shielding is a common problem after uncemented THA that may lead to proximal femoral atrophy and consecutive aseptic loosening. Methods: In 143 patients with 154 uncemented CLS-stems periprosthetic bone mineral density (BMD) was measured using DXA after a mean of 12 years (10–15) postoperatively (T1). Five years later the same group of patients was examined at a mean of 17 years (range: 15–20) (T2) using the identical protocol. Results: We obtained a complete prospective set of data of two consecutive DXA measurements in 76 cases (32 men, 44 women). In all cases regular bone ongrowth did occur and there were no signs of radiographic loosening (T1 and T2). On radiographic evaluation there was no significant change in periprosthetic bone formation in all Gruen zones between T1 and T2. There was no significant change in activity and BMD. In male patients we found no significant changes in periprosthetic BMD (netavg T1–T2: −1,19%, p< 0,01), in female patients there was no significant difference either (netavg T1–T2: −1,32%,p< 0,01). We analyzed the differences in BMD in all Gruen zones (zone 1–7) comparing T1 and T2 and found no significant differences in any zone (p< 0,01). Conclusion: This study showed that there is no significant change in periprosthetic bone mineral density in the long term using the uncemented CLS stem. There was not a single case of stress shielding in the long term. Once osseous integration has occurred the periprostethic BMD changes remain minimal in the long term

We aimed to evaluate the precision and longitudinal sensitivity of measurement of bone mineral density (BMD) in the pelvis and to determine the effect of bone cement on the measurement of BMD in femoral regions of interest (ROI) after total hip arthroplasty (THA). A series of 29 patients had duplicate dual-energy x-ray absorptiometry (DXA) scans of the hip within 13 months of THA. Pelvic analyses using 3- and 4-ROI models gave a coefficient of variation (CV) of 2.5% to 3.6% and of 2.5% to 4.8%, respectively. Repeat scans in 17 subjects one year later showed a significant change in BMD in three regions using the 4-ROI model, compared with change in only one region with the 3-ROI model (p < 0.05). Manual exclusion of cement from femoral ROIs increased the net CV from 1.6% to 3.6% (p = 0.001), and decreased the measured BMD by 20% (t = 12.1, p < 0.001). Studies of two cement phantoms in vitro showed a small downward drift in bone cement BMD giving a measurement error of less than 0.03 g/cm. 2. /year associated with inclusion of cement in femoral ROIs. Changes in pelvic periprosthetic BMD are best detected using a 4-ROI model. Analysis of femoral ROI is more precise without exclusion of cement although an awareness of its effect on the measurement of the BMD is needed

Purpose. Use of a large femoral head metal-on-metal bearing in total hip arthroplasty may offer an advantage in terms of dislocation rates and more natural joint kinematics. The acetabular component is more rigid however in these prostheses and if not placed accurately can lead to increased levels of metal ion release. A prospective randomized controlled trial was conducted to quantify bone mineral density on the acetabular side, as well as compare metal ion levels from a standard metal-on-polyethylene bearing to a large head metal-on-metal bearing in primary total hip arthroplasty. Method. Fifty patients were randomized to receive total hip arthroplasty with either the CONSERVE A-Class Total Hip with BFH femoral head or the Lineage acetabular component with polyethylene insert and cobalt chrome femoral head. There were 27 females (11 BFH) and 23 males (14 BFH), with a mean overall age of 61.6 (range 47.7–73.2). Serum levels of cobalt, chromium, and titanium were measured at regular intervals up to two years. Harris Hip Score, WOMAC, UCLA, and RAND-36 were completed at these same intervals. Standard radiographs as well as periprosthetic BMD were performed. Results. Bone mineral density in acetabular zones II, III, and IV was greater in the BFH group compared with the metal on poly group (p= 0.030, 0.046, and 0.019 respectively). Serum levels of cobalt (2.31 microg/mL vs 0.23 microg/mL, p=<0.001) and chromium (1.53 microg/mL vs 0.21 microg/mL, p=<0.001) were statistically higher in the BFH group compared with the metal-on-polyethylene group at one year post-op. There was no significant difference in serum titanium levels between groups. Conclusion. At short term follow up the load transfer to the acetabular bony bed differed between the two groups, with the more rigid shells demonstrating increased BMD in certain zones when compared with metal on poly. Serum levels of certain ions were 7–15 fold higher in the metal-on-metal large femoral head design compared with a standard metal-on-polyethylene. We await results on any clinical differences in performance and complications in this group of patients. Systemic implications of these ion levels are not known and further study is warranted

Our aim was to determine the precision of the measurements of bone mineral density (BMD) by dual-energy x-ray absorptiometry in the proximal femur before and after implantation of an uncemented implant, with particular regard to the significance of retro- and prospective studies. We examined 60 patients to determine the difference in preoperative BMD between osteoarthritic and healthy hips. The results showed a preoperative BMD of the affected hip which was lower by a mean of 4% and by a maximum of 9% compared with the opposite side. In addition, measurements were made in the operated hip before and at ten days after operation to determine the effect of the implantation of an uncemented custom-made femoral stem. The mean increase in the BMD was 8% and the maximum was 24%. Previous retrospective studies have reported a marked loss of BMD on the operated side. The precision of double measurements using a special foot jig showed a modified coefficient of variation of 0.6% for the non-operated side in 15 patients and of 0.6% for the operated femur in 20 patients. The effect of rotation on the precision of the measurements after implantation of an uncemented femoral stem was determined in ten explanted femora and for the operated side in ten patients at 10° rotation and in 20 patients at 30° rotation. Rotation within 30° influenced the precision in studies in vivo and in vitro by a mean of 3% and in single cases in up to 60%. Precise prediction of the degree of loss of BMD is thus only possible in prospective cross-sectional measurements, since the effect of the difference in preoperative BMD, as well as the apparent increase in BMD after implantation of an uncemented stem, is not known from retrospective studies. The DEXA method is a reliable procedure for determining periprosthetic BMD when positioning and rotation are strictly controlled

Periprosthetic bone loss is identified after inserting a hip prosthesis and is many times a result of stress shielding or altered loading of the proximal femur. Depending on the severity, the bone loss may threaten the prosthesis survival. The current study investigated the effect of cyclic etidronate therapy on periprosthetic and contralateral bone mineral density (BMD) in an one-year, prospective, randomized, double-blind study on 46 patients after cemented hip arthroplasty. Etidronate was administered orally in a regimen repeated every 14 weeks and periprosthetic BMD was measured with dual energy X-ray absorptiometry (DXA) in the total periprosthetic area and in the seven Gruen Zones at 1 week (baseline), 6 weeks, 3 months, 6 months, and 12 months postoperatively. In the etidronate group there were significant temporal BMD decreases measured in Gruen Zones 2, 3, 6, and 7 as well as in the entire proximal femur; the greatest decrease was 11.1% and was measured in Zone 2 at 12 months. Also in the etidronate group, there was a significant 3.4% increase in BMD of the spine at 12 months. In the placebo group there were significant temporal BMD decreases measured in Gruen Zones 1, 2, 3, 4, 6, and 7 as well as in the entire proximal; the greatest decrease was 16.4% and was measured in Zone 7 at 12 months. There were no significant differences between the mean BMD measurements of the etidronate and placebo groups with the exception of the mean percent change in the spine at 6 months and 12 months, and in Gruen Zone 3 at 6 months; in all three cases the etidronate group had significantly greater mean values. These findings suggest that cyclic etidronate therapy has no significant effect in surpressing the periprosthetic bone loss following cemented hip arthroplasty