Bioactive glass granules versus standard autologous and allogeneic bone grafts: a randomized trial of 49 adult bone tumor patients with a 10-year follow-up.

BACKGROUND AND PURPOSE: As a synthetic bone void filler, bioactive glasses (BGs) may enhance angiogenesis and osteogenesis. In this randomized trial, we compared the clinical efficacy of BG granules and standard bone grafts in patients undergoing surgery for benign bone tumors. PATIENTS AND METHODS: 49 recruited patients were randomized to receive BG granules or undergo conventional bone grafting to fill defects following tumor removal. As the standard of care, small-sized defects were filled with autologous graft, and large-sized defects were filled with allogeneic graft. The primary endpoint was treatment success at 1 year, defined by no reoperation, no tumor recurrence, and no device-related adverse events. Secondary endpoints included patient-reported outcomes (Rand-36 and pain scores) and quantitative assessment of blood flow and metabolic activity by means of 18F-fluoride PET/CT imaging. As an off-trial group, 15 children and adolescents (age < 18 years) underwent tumor removal and BG-filling, without randomization. RESULTS: At 1-year, 21 of 25 BG-treated patients (risk estimate 0.84, 95% confidence interval [CI] 0.70-0.98) and 20 of 24 patients in the standard of care group (0.83, CI 0.68-0.98) met the criteria for treatment success. The groups had similar Rand-36 scores. In patients with small defects, BG filling was associated with shorter operative time and less postoperative pain at 1 month. In patients with large defects, blood flow was similar, but BG-filled defects showed higher metabolic activity than allograft-filled defects at 1-year. The survey of the postoperative period ≥10 years revealed no BG-related adverse events. INTERPRETATION: BG granules had similar overall rates of treatment success compared with autografts and allografts, but large-scale trials are needed for the confirmation of clinical equivalence. The extended metabolic activity confirms the expected cellular responses of osseointegrated BG granules.

Bone Mineral Density and Cortical-Bone Thickness of the Distal Radius Predict Femoral Stem Subsidence in Postmenopausal Women.

BACKGROUND: The distal radius is an optional site for evaluation of bone quality in postmenopausal women before cementless total hip arthroplasty. We hypothesized that dual-energy X-ray absorptiometry (DXA) and pulse-echo ultrasonometry of the distal radius may help discriminate subjects at high risk of femoral stem subsidence. METHODS: A prospective cohort of postmenopausal women with primary hip osteoarthritis underwent total hip arthroplasty with implantation of a parallel-sided femoral stem. Postoperative stem migration was measured using radiostereometric analysis. Preoperatively, subjects had multisite DXA measurement of bone mineral density (BMD) and pulse-echo ultrasonometry of the cortical-bone thickness. The diagnostic abilities of these methods to discriminate <2 mm and ≥2 mm femoral stem subsidence were tested. RESULTS: The accuracy of the distal radius BMD and cortical-bone thickness of the distal radius were moderate (area under the curve, 0.737 and 0.726, respectively) in discriminating between <2 mm and ≥2 mm stem subsidence. Women with low cortical-bone thickness of the radius were more likely (odds ratio = 6.7; P = .002) to develop stem subsidence ≥2 mm. These subjects had lower total hip BMD (P = .007) and reduced thickness of the medial cortex of the proximal femur (P = .048) with lower middle (P < .001) and distal (P = .004) stem-to-canal fill ratios. CONCLUSION: Femoral stem stability and resistance to subsidence are sensitive to adequate bone stock and unaltered anatomy. DXA and pulse-echo ultrasonometry of the distal radius may help discriminate postmenopausal women at high risk of stem subsidence.

Good stability of a cementless, anatomically designed femoral stem in aging women: a 9-year RSA study of 32 patients.

Background and purpose - We previously reported a transient, bone mineral density (BMD)-dependent early migration of anatomically designed hydroxyapatite-coated femoral stems with ceramic-ceramic bearing surfaces (ABG-II) in aging osteoarthritic women undergoing cementless total hip arthroplasty. To evaluate the clinical significance of the finding, we performed a follow-up study for repeated radiostereometric analysis (RSA) 9 years after surgery. Patients and methods - Of the 53 female patients examined at 2 years post-surgery in the original study, 32 were able to undergo repeated RSA of femoral stem migration at a median of 9 years (7.8-9.3) after surgery. Standard hip radiographs were obtained, and the subjects completed the Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index outcome questionnaires. Results - Paired comparisons revealed no statistically significant migration of the femoral stems between 2 and 9 years post-surgery. 1 patient exhibited minor but progressive RSA stem migration. All radiographs exhibited uniform stem osseointegration. No stem was revised for mechanical loosening. The clinical outcome scores were similar between 2 and 9 years post-surgery. Interpretation - Despite the BMD-related early migration observed during the first 3 postoperative months, the anatomically designed femoral stems in aging women are osseointegrated, as evaluated by RSA and radiographs, and exhibit good clinical function at 9 years.

Is Model-based Radiostereometric Analysis Suitable for Clinical Trials of a Cementless Tapered Wedge Femoral Stem?

BACKGROUND: In clinical trials of THA, model-based radiostereometric analysis (RSA) techniques may be less precise than conventional marker-based RSA for measurement of femoral stem rotation. We verified the accuracy and clinical precision of RSA based on computer-aided design models of a cementless tapered wedge femoral stem. QUESTIONS: We asked: (1) Is the accuracy of model-based RSA comparable to that of marker-based RSA? (2) What is the clinical precision of model-based RSA? METHODS: Model-based RSA was performed using combined three-dimensional computer-aided design models of the stem and head provided by the implant manufacturer. The accuracy of model-based RSA was compared with that of marker-based RSA in a phantom model using micromanipulators for controlled translation in three axes (x, y, z) and rotation around the y axis. The clinical precision of model-based RSA was evaluated by double examinations of patients who had arthroplasties (n = 24) in an ongoing trial. The clinical precision was defined as being at an acceptable level if the number of patients needed for a randomized trial would not differ from a trial done with conventional marker-based RSA (15-25 patients per group). RESULTS: The accuracy of model-based RSA was 0.03 mm for subsidence (translation along the y axis) (95% CI for the difference between RSA measurements and actual displacement measured with micrometers, -0.03-0.00) and 0.39° for rotation around the y axis (95% CI, -0.41 to -0.06). The accuracy of marker-based RSA was 0.06 mm for subsidence (95% CI, -0.04-0.01; p = 0.728 compared with model-based RSA) and 0.18° for the y axis rotation (95% CI, -0.23 to -0.07; p = 0.358). The clinical precision of model-based RSA was 0.14 mm for subsidence (95% CI for the difference between double examinations, -0.02-0.04) and 0.79° for the y axis rotation (95% CI, -0.16-0.18). CONCLUSIONS: The accuracy of model-based RSA for measurement of the y axis rotation was not quite as high as that of marker-based RSA, but its clinical precision is at an acceptable level. CLINICAL RELEVANCE: Model-based RSA may be suitable for clinical trials of cementless tapered wedge femoral stem designs.

Increased migration of uncemented acetabular cups in female total hip arthroplasty patients with low systemic bone mineral density. A 2-year RSA and 8-year radiographic follow-up study of 34 patients.

BACKGROUND AND PURPOSE: Low bone mineral density (BMD) may jeopardize the initial component stability and delay osseointegration of uncemented acetabular cups in total hip arthroplasty (THA). We measured the migration of uncemented cups in women with low or normal BMD. PATIENTS AND METHODS: We used radiostereometric analysis (RSA) to measure the migration of hydroxyapatite-coated titanium alloy cups with alumina-on-alumina bearings in THA of 34 female patients with a median age of 64 (41-78) years. 10 patients had normal BMD and 24 patients had low systemic BMD (T-score ≤ -1) based on dual-energy X-ray absorptiometry (DXA). Cup migration was followed with RSA for 2 years. Radiographic follow-up was done at a median of 8 (2-10) years. RESULTS: Patients with normal BMD did not show a statistically significant cup migration after the settling period of 3 months, while patients with low BMD had a continuous proximal migration between 3 and 12 months (p = 0.03). These differences in cup migration persisted at 24 months. Based on the perceived risk of cup revision, 14 of the 24 cases were "at risk" (proximal translation of 0.2 to 1.0 mm) in the low-BMD group and 2 of the 10 cases were "at risk" in the normal-BMD group (odds ratio (OR) = 8.0, 95% CI: 1.3-48). The radiographic follow-up showed no radiolucent lines or osteolysis. 2 cups have been revised for fractures of the ceramic bearings, but none for loosening. INTERPRETATION: Low BMD contributed to cup migration beyond the settling period of 3 months, but the migrating cups appeared to osseointegrate eventually.

Local delivery of a selective androgen receptor modulator failed as an anabolic agent in a rat bone marrow ablation model.

BACKGROUND AND PURPOSE: Selective androgen receptor modulators (SARMs) have been developed to have systemic anabolic effects on bones and muscles without the adverse effects of steroidal androgens. One unexplored therapeutic option is the targeted application of SARMs for the enhancement of local new bone formation. We evaluated the osteogenic efficacy of a locally released SARM (ORM-11984). METHODS: ORM-11984 was mixed with a copolymer of L-lactide and ɛ-caprolactone (PLCL). An in vitro dissolution test confirmed the sustainable release of ORM-11984 from the matrix. A bone marrow ablation model was used in female Sprague-Dawley rats. Implants containing 10%, 30%, or 50% ORM-11984 by weight or pure PLCL were inserted into the medullary canal of the ablated tibia. At 6 and 12 weeks, the volume of intramedullary new bone and the perimeter of bone-implant contact were measured by micro-computed tomography and histomorphometry. RESULTS: Contrary to our hypothesis, there was a negative correlation between the amount of new bone around the implant and the dose of ORM-11984. There was only a mild (and not statistically significant) enhancement of bone formation in ablated bones subjected to the lowest dose of the SARM (10%). INTERPRETATION: This study suggests that intramedullary/endosteal osteogenesis had a negative, dose-dependent response to locally released SARM. This result highlights the complexity of androgenic effects on bones and also suggests that there are biological limits to the targeted local application of SARMs.

Adherence of hip and knee arthroplasty studies to RSA standardization guidelines. A systematic review.

BACKGROUND AND PURPOSE: Guidelines for standardization of radiostereometry (RSA) of implants were published in 2005 to facilitate comparison of outcomes between various research groups. In this systematic review, we determined how well studies have adhered to these guidelines. METHODS: We carried out a literature search to identify all articles published between January 2000 and December 2011 that used RSA in the evaluation of hip or knee prosthesis migration. 2 investigators independently evaluated each of the studies for adherence to the 13 individual guideline items. Since some of the 13 points included more than 1 criterion, studies were assessed on whether each point was fully met, partially met, or not met. RESULTS: 153 studies that met our inclusion criteria were identified. 61 of these were published before the guidelines were introduced (2000-2005) and 92 after the guidelines were introduced (2006-2011). The methodological quality of RSA studies clearly improved from 2000 to 2011. None of the studies fully met all 13 guidelines. Nearly half (43) of the studies published after the guidelines demonstrated a high methodological quality and adhered at least partially to 10 of the 13 guidelines, whereas less than one-fifth (11) of the studies published before the guidelines had the same methodological quality. Commonly unaddressed guideline items were related to imaging methodology, determination of precision from double examinations, and also mean error of rigid-body fitting and condition number cutoff levels. INTERPRETATION: The guidelines have improved methodological reporting in RSA studies, but adherence to these guidelines is still relatively low. There is a need to update and clarify the guidelines for clinical hip and knee arthroplasty RSA studies.

Risk prediction of second hip fracture by bone and muscle density of the hip varies with time after first hip fracture: A prospective cohort study.

Purpose: Predictors of 'imminent' risk of second hip fracture are unknown. The aims of the study were to explore strength of hip areal bone mineral density (aBMD), and muscle area and density for predicting second hip fracture at different time intervals. Methods: Data of the Chinese Second Hip Fracture Evaluation were analyzed, a longitudinal study to evaluate the risk of second hip fracture (of the contralateral hip) by using CT images obtained immediately after first hip fracture. Muscle cross-sectional area and density were measured of the gluteus maximus (G.MaxM) and gluteus medius and minimus (G.Med/MinM) and aBMD of the proximal femur at the contralateral unfractured side. Patients were followed up for a median time of 4.5 years. Separate Cox models were used to predict second hip fracture risk at different time intervals after first event adjusted for age, sex, BMI and diabetes. Results: The mean age of subjects with imminent (within 1st or 2nd year) second hip fracture was 79.80 ± 5.16 and 81.56 ± 3.64 years. In the 1st year after the first hip fracture, femoral neck (FN) aBMD predicted second hip fracture (HR 5.88; 95 % CI, 1.32-26.09). In the remaining years of follow-up after 2nd year, muscle density predicted second hip fracture (G.MaxM HR 2.13; 95 % CI, 1.25-3.65,G.Med/MinM HR 2.10; 95 % CI, 1.32-3.34). Conclusions: Our results show that femoral neck aBMD is an important predictor for second hip fracture within the first year and therefore suggest supports the importance concept of early and rapid-acting bone-active drugs to increase hip BMD. In addition, the importance of muscle density predicting second hip fracture after the second year suggest post hip fracture rehabilitation and exercise programs could also be important to reduce muscle fatty infiltration.

Characterization of porous glass fiber-reinforced composite (FRC) implant structures: porosity and mechanical properties.

The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC). Implants made of the FRC structures are intended for cranial applications. The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix. Four groups of porous FRC specimens were prepared with a different amount of resin matrix. Control group contained specimens of fibers, which were bound together with sizing only. Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method. Mechanical properties of the specimens were measured with a tensile test. The amount of resin matrix in the specimens had an effect on the microstructure. Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content. In control group, total porosity was 94.2 % (median). Correlations with resin content were obtained for all micro-CT based parameters except TbPf. The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content. The tensile strength in control group was 18.9 MPa (median). There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters. This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed.

MicroRNAs miR-96, miR-124, and miR-199a regulate gene expression in human bone marrow-derived mesenchymal stem cells.

MicroRNAs are small non-coding RNAs that control gene expression at the post-transcriptional level by binding to 3'-untranslated regions (3'-UTR) of their target mRNAs. They present a promising tool to delineate the molecular mechanisms regulating differentiation of human mesenchymal stromal cells (hMSCs) and to improve the controlled differentiation of hMSCs in therapeutic applications. Here we show that three microRNAs, miR-96, miR-124, and miR-199a, were differentially expressed during osteogenic, adipogenic, and chondrogenic induction of human bone marrow-derived MSCs. miR-96 expression was increased during osteogenesis and adipogenesis, but not during chondrogenesis. miR-124 was exclusively expressed in adipocytes, whereas miR-199a was upregulated in osteoblasts and chondrocytes. Furthermore, functional studies with synthetic miRNA precursors and inhibitors demonstrated that miR-96, miR-124, and miR-199a regulated the expression of genes important for hMSC differentiation, such as aggrecan, transcription factor SOX9, and fatty acid binding protein 4 (FABP4). Modulation of miR-96, miR-124, and miR-199a expression may thus be useful in specific targeting of hMSC differentiation, for e.g., MSC-based therapies. J

Polysaccharide-coated thermosets for orthopedic applications: from material characterization to in vivo tests.

The long-term stability and success of orthopedic implants depend on the osseointegration process, which is strongly influenced by the biomaterial surface. A promising approach to enhance implant integration involves the modification of the surface of the implant by means of polymers that mimic the natural components of the extracellular matrix, for example, polysaccharides. In this study, methacrylate thermosets (bisphenol A glycidylmethacrylate/triethyleneglycol dimethacrylate), a widely used composition for orthopedic and dental applications, have been coated by electrostatic deposition of a bioactive chitosan-derivative. This polysaccharide was shown to induce osteoblasts aggregation in vitro, to stimulate cell proliferation and to enhance alkaline phosphatase activity. The coating deposition was studied by analyzing the effect of pH and ionic strength on the grafting of the polysaccharide. Contact angle studies show that the functionalized material displays a higher hydrophilic character owing to the increase of surface polar groups. The mechanical properties of the coating were evaluated by nanoindentation studies which point to higher values of indentation hardness and modulus (E) of the polysaccharide surface layer, while the influence of cyclic stress on the construct was assessed by fatigue tests. Finally, in vivo tests in minipigs showed that the polysaccharide-based implant showed a good biocompatibility and an ability for osseointegration at least similar to that of the titanium Ti6Al4V alloy with roughened surface.

Low BMD affects initial stability and delays stem osseointegration in cementless total hip arthroplasty in women: a 2-year RSA study of 39 patients.

BACKGROUND AND PURPOSE: Immediate implant stability is a key factor for success in cementless total hip arthroplasty (THA). Low bone mineral density (BMD) and age-related geometric changes of the proximal femur may jeopardize initial stability and osseointegration. We compared migration of hydroxyapatite-coated femoral stems in women with or without low systemic BMD. PATIENTS AND METHODS: 61 female patients with hip osteoarthritis were treated with cementless THA with anatomically designed hydroxyapatite-coated femoral stems and ceramic-ceramic bearing surfaces (ABG-II). Of the 39 eligible patients between the ages of 41 and 78 years, 12 had normal systemic BMD and 27 had osteopenia or osteoporosis. According to the Dorr classification, 21 had type A bone and 18 had type B. Translational and rotational migration of the stems was evaluated with radiostereometric analysis (RSA) up to 2 years after surgery. RESULTS: Patients with low systemic BMD showed higher subsidence of the femoral stem during the first 3 months after surgery than did those with normal BMD (difference = 0.6, 95% CI: 0.1-1.1; p = 0.03). Low systemic BMD (odds ratio (OR) = 0.1, CI: 0.006-1.0; p = 0.02), low local hip BMD (OR = 0.3, CI: 0.1-0.7; p = 0.005) and ageing (OR = 1.1, CI: 1.0-1.2; p = 0.02) were risk factors for delayed translational stability. Ageing and low canal flare index were risk factors for delayed rotational stabilization (OR = 3, CI: 1.1-9; p = 0.04 and OR = 1.1, CI: 1.0-1.2; p = 0.02, respectively). Harris hip score and WOMAC score were similar in patients with normal systemic BMD and low systemic BMD. INTERPRETATION: Low BMD, changes in intraosseous dimensions of the proximal femur, and ageing adversely affected initial stability and delayed osseointegration of cementless stems in women.

Denosumab in Cementless Total Hip Arthroplasty: Multivariate Reanalysis of 3D Femoral Stem Migration and the Influence on Outliers.

In cementless total hip arthroplasty, adequate implant stability is necessary for the success of osseointegration and rapid clinical recovery. Postoperative femoral stem migration, measured by radiostereometric analysis (RSA), defines the initial stability achieved during surgical implantation. In a recent trial of 65 postmenopausal women randomized 1:1 denosumab:placebo, denosumab failed to reduce the initial migration of a cementless femoral stem despite the successful prevention of periprosthetic bone loss. The trial applied the current RSA standard, which examined stem migration on an axis-by-axis basis and did not consider more complex three-dimensional (3D) migration. Therefore, we performed a reanalysis of the trial data using a multivariate hierarchical linear mixed model (LMM). As an additional limitation, the data included influential outliers. Women with normal bone mineral density exhibited significantly (p = 0.036) less stem subsidence compared with osteopenic and osteoporotic women. Denosumab significantly decreased the variance of stem migration in osteopenic and osteoporotic women. The mean magnitude of 3D stem migration did not differ between denosumab-treated and placebo-treated women (p = 0.820). After application of a common statistical definition for RSA outlier identification, there were eight (12%) outliers, six in the placebo group and two in the denosumab group (p = 0.149). After exclusion of the outliers, the repeated LMM analysis demonstrated a trending difference in 3D stem migration (p = 0.086), with a significant difference of z-axis rotation (valgus-varus tilt) of the femoral stem (p = 0.029). The observed effect size was small and without clinically important differences in postoperative recovery. Based on a Monte Carlo simulation with random-generated 3D migration data, multivariate LMM showed greater statistical power than univariate analyses. The application of hierarchical LMM facilitated the analysis of implant migration as a factual 3D event. The observed trend in the lower number of RSA outliers in denosumab-treated subjects warrants powered large-scale trials. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Instrumented spondylodesis in degenerative spondylolisthesis with bioactive glass and autologous bone: a prospective 11-year follow-up.

A prospective long-term follow-up study of bioactive glass (BAG)-S53P4 and autogenous bone (AB) used as bone graft substitutes for posterolateral spondylodesis in treatment of degenerative spondylolisthesis during 1996 to 1998 was conducted. The surgical procedure was a standardized instrumented posterolateral fusion that used USS/VAS. BAG was implanted on the left side of the fusion bed and AB on the right side. The operative outcome was evaluated on x-rays and computed tomography scans, and a clinical examination was also performed. Seventeen patients (12 women, 5 men) participated in the 11-year follow-up. The mean Oswestry Disability Index score at the follow-up was 21 (range 0 to 52), compared with 49 (range 32 to 64) at the preoperative time. A solid bony fusion was seen on computed tomography scans on the AB side in all patients and on the BAG side in 12 patients. The fusion rate of all fusion sites (n=41) for BAG as a bone substitute was 88% at the L4/5 level and 88% at the L5/S1 level. The use of BAG as a bone graft extender can be considered as a good alternative in spinal surgery in the future.

Contributing factors to the initial femoral stem migration in cementless total hip arthroplasty of postmenopausal women.

In cementless total hip arthroplasty (THA), femoral stems rely on the initial press-fit fixation against cortical bone to achieve osseointegration. Decreased bone mineral density (BMD) in postmenopausal women poses natural difficulties in achieving axial and rotational femoral stem stability. The present study examined contributing demographic, surgery-related and postoperative factors in determining the magnitude of early stem migration prior to osseointegration. A prospective cohort of 65 postmenopausal women with hip osteoarthritis (Dorr type A or B femur anatomy) underwent THA with implantation of an uncemented parallel-sided femoral component. Postoperative femoral stem translation and rotation were measured using model-based radiostereometric analysis. Based on analysis of covariance, which controlled for outliers and randomized antiresorptive treatment with denosumab or placebo, none of the analyzed demographics (including BMI) and surgery-related variables (including the stem-to-canal fil ratio) was associated with stem subsidence. Stem subsidence (mean 1.8 mm, 95% CI 1.2 to 2.4) occurred even in women with normal hip BMD. Total hip BMD and postoperative walking activity (measured three months after surgery) were significantly associated with stem rotation, and height acted as a confounding factor. The effect of walking activity on stem rotation was significant at 5 months (p = 0.0083) and at 11 months (p = 0.0117). This observation confirms the previous results of instrumented hip prostheses on torsional moments affecting stems during daily activities. High-resolution imaging modalities of local bone quality are needed to explore reasons for RSA-measurable stem subsidence even in women with normal hip BMD.

Volumetric Bone Mineral Density in Cementless Total Hip Arthroplasty in Postmenopausal Women: Effects on Primary Femoral Stem Stability and Clinical Recovery.

BACKGROUND: In cementless total hip arthroplasty, femoral stems should preferably not migrate at all postoperatively. This goal is difficult to achieve in postmenopausal women with impaired bone quality. Here, we explored the clinical importance of initial stem migration, measured by radiostereometric analysis (RSA), in women who underwent quantitative computed tomography (CT) of the involved hip preoperatively. METHODS: A prospective cohort of 65 postmenopausal women (mean age, 69 years) with hip osteoarthritis and Dorr type-A or B femoral anatomy underwent total hip arthroplasty with implantation of a tapered, single-wedge femoral stem. Volumetric bone mineral density (BMD) was measured using quantitative CT. Femoral stem translation and rotation were measured using model-based RSA within 3 days after the surgical procedure and were repeated at 3, 5, and 11 months. Postoperative recovery parameters included walking speed, walking activity, and patient-reported outcome measures. Subjects were categorized into 2 groups according to the magnitude of initial 5-month stem subsidence (<2 mm or ≥2 mm); RSA outliers (n = 7) were analyzed separately. RESULTS: Subjects with stem subsidence of ≥2 mm (mean, 3.09 mm [95% confidence interval (CI), 2.70 to 3.47 mm]) had lower intertrochanteric volumetric BMD (p = 0.008). Subjects with subsidence of <2 mm (mean, 0.80 mm [95% CI, 0.51 to 1.09 mm]) had faster improvement of patient-reported outcome measures and exhibited faster walking speed (p = 0.007) and greater walking activity (p = 0.010) at 11 months as well as better Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (p = 0.002) and RAND 36-Item Health Survey mental component scores (p = 0.006) at 2 years. All cohort stems were osseointegrated at 2 years. CONCLUSIONS: Femoral stem stability and resistance to subsidence were sensitive to adequate intertrochanteric volumetric BMD. Low intertrochanteric volumetric BMD was associated with greater stem migration. With initial migration, clinical recovery was slower and patient-reported outcome measures were less satisfactory. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Female patients with low systemic BMD are prone to bone loss in Gruen zone 7 after cementless total hip arthroplasty.

BACKGROUND AND PURPOSE: Factors that lead to periprosthetic bone loss following total hip arthroplasty (THA) may not only depend on biomechanical implant-related factors, but also on various patient-related factors. We investigated the association between early changes in periprosthetic bone mineral density (BMD) and patient-related factors. PATIENTS AND METHODS: 39 female patients underwent cementless THA (ABG II) with ceramic-ceramic bearing surfaces. Periprosthetic BMD in the proximal femur was determined with DXA after surgery and at 3, 6, 12, and 24 months. 27 patient-related factors were analyzed for their value in prediction of periprosthetic bone loss. RESULTS: Total periprosthetic BMD was temporarily reduced by 3.7% at 3 months (p < 0.001), by 3.8% at 6 months (p < 0.01), and by 2.6% at 12 months (p < 0.01), but recovered thereafter up to 24 months. Preoperative systemic osteopenia and osteoporosis, but not the local BMD of the operated hip, was predictive of bone loss in Gruen zone 7 (p = 0.04), which was the only region with a statistically significant decrease in BMD (23%, p < 0.001) at 24 months. Preoperative serum markers of bone turnover predicted the early temporary changes of periprosthetic BMD. The other patient-related factors failed to show any association with the periprosthetic BMD changes. INTERPRETATION: Female patients with low systemic BMD show greater bone loss in Gruen zone 7 after cementless THA than patients with normal BMD. Systemic DXA screening for osteoporosis in postmenopausal patients before THA could be used to identify patients in need of prophylactic anti-resorptive therapy.