Continuous periprosthetic bone loss but preserved stability for a collum femoris-preserving stem: follow-up of a prospective cohort study of 21 patients with dualenergy X-ray absorptiometry and radiostereometric analysis with minimum 8 years of follow-up

Background and purpose — We previously described a decrease in bone mineral density (BMD) in the calcar region 2 years after insertion of the collum femoris-preserving (CFP) stem, but the implants were stable. Now we have examined the long-term changes in periprosthetic BMD and stability of the CFP stem. Patients and methods — We conducted a minimum 8-year follow-up of 21 patients from our original investigation. We examined periprosthetic BMD by dual-energy X-ray absorptiometry (DEXA) and implant stability by radiostereometric analysis (RSA). Results — Between 2 and 8 years 1 stem was revised due to aseptic loosening. Between 2 and 8 years we found a 14% (95% confidence interval [CI] 9–19) reduction in BMD in Gruen zone 6 and 17% (CI 6–28) in Gruen zone 7. From baseline the reduction in BMD was 30% (CI 23–36) in Gruen zone 6, 39% (CI 31–47) in Gruen zone 7, and 19% (CI 14–23) in Gruen zone 2. Between 2 and 8 years, RSA (n = 17) showed a mean translation along the stem axis of 0.02mm (CI –0.02 to 0.06) and a mean rotation around the stem axis of 0.08° (CI –0.26 to 0.41). From baseline mean subsidence was 0.07 mm (CI –0.16 to 0.03) and mean rotation around the stem axis was 0.23° (CI –0.23 to 0.68) at 8 years. Interpretation — There was continuous loss of proximomedial BMD at 8 years while the CFP stem remained stable. Proximal periprosthetic bone loss cannot be prevented by this stem.

Predicting Bone Remodeling in Response to Orthopedic Implantations: Computational Study Using a Mechano-Biochemical Model

Periprosthetic bone loss following orthopedic implantations is a serious concern leading to the premature failure of the implants. Therefore, investigating bone remodeling in response to orthopedic implantations is of paramount importance for the purpose of designing long lasting prostheses. In this study, a predictive bone remodeling model (Thermodynamic-based model) was employed to simulate the long-term response of femoral density to total hip arthroplasty (THA), bone fracture plating and intramedullary (IM) nailing. The ability of the model in considering the coupling effect between mechanical loading and bone biochemistry is its unique characteristic. This research provided quantitative data for monitoring bone density changes throughout the femoral bone. The results obtained by the thermodynamic-based model agreed well with the bone morphology and the literature. The study revealed that the most significant periprosthetic bone loss in response to THA occurred in calcar region (Gruen zone 7). Conversely, the region beneath the hip stem (Gruen zone 4) experienced the lowest bone mineral density (BMD) changes. It was found that the composite hip implant and IM nail were more advantageous over the metallic ones as they induced less stress shielding and provided more uniform bone density changes following the surgery. The research study also showed that, due to plating, the areas beneath the bone fracture plate experienced severe bone loss. However, some level of bone formation was observed at the vicinity of the most proximal and distal screw holes in both lateral and anterior plated femurs. Furthermore, in terms of long-term density distributions, the anterior plating was not superior to the lateral plating.

Predicting Bone Remodeling in Response to Orthopedic Implantations: Computational Study Using a Mechano-Biochemical Model

Periprosthetic bone loss following orthopedic implantations is a serious concern leading to the premature failure of the implants. Therefore, investigating bone remodeling in response to orthopedic implantations is of paramount importance for the purpose of designing long lasting prostheses. In this study, a predictive bone remodeling model (Thermodynamic-based model) was employed to simulate the long-term response of femoral density to total hip arthroplasty (THA), bone fracture plating and intramedullary (IM) nailing. The ability of the model in considering the coupling effect between mechanical loading and bone biochemistry is its unique characteristic. This research provided quantitative data for monitoring bone density changes throughout the femoral bone. The results obtained by the thermodynamic-based model agreed well with the bone morphology and the literature. The study revealed that the most significant periprosthetic bone loss in response to THA occurred in calcar region (Gruen zone 7). Conversely, the region beneath the hip stem (Gruen zone 4) experienced the lowest bone mineral density (BMD) changes. It was found that the composite hip implant and IM nail were more advantageous over the metallic ones as they induced less stress shielding and provided more uniform bone density changes following the surgery. The research study also showed that, due to plating, the areas beneath the bone fracture plate experienced severe bone loss. However, some level of bone formation was observed at the vicinity of the most proximal and distal screw holes in both lateral and anterior plated femurs. Furthermore, in terms of long-term density distributions, the anterior plating was not superior to the lateral plating.

The local concentration of Ca2+ correlates with BMP7 expression and osseointegration in patients with total hip arthroplasty

Background A successful osseointegration of total hip arthroplasty (THA) relies on the interplay of implant surface and bone marrow microenvironment. This study was undertaken to investigate the impact of perioperative biochemical molecules (Ca2+, Mg2+, Zn2+, VD, PTH) on the bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells) in the metaphyseal region of the femoral head, and further on the bone mineral density (BMD) of Gruen R3. Methods Bone marrow aspirates were obtained from the discarded metaphysis region of the femoral head in 51 patients with THA. Flow cytometry was used to measure the Stro-1+ expressing cells. ELISA was used to measure the concentrations of bone morphologic proteins (BMP2 and BMP7) and the content of TRACP5b in serum. TRAP staining was used to detect the osteoclast activity in the hip joint. The perioperative concentrations of the biochemical molecules above were measured by radioimmunoassay. The BMD of Gruen zone R3 was examined at 6 months after THA, using dual-energy X-ray absorptiometry (DEXA). Results Our data demonstrated that the concentration of Ca2+ was positively correlated with BMP7 expression, and with the postoperative BMD of Gruen zone R3. However, the concentration of Mg2+ had little impact on the R3 BMD, although it was negatively correlated with the expression of BMP7. Osteoclast activity in hip joint tissue of patients with femoral neck fractures was increased. Compared with the patients before THA, the levels of TRACP5b in serum of patients after THA were decreased. The data also suggested that the other biochemical molecules, such as Zn2+, VD, and PTH, were not significantly correlated with any bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells). The postoperative R3 BMD of patients of different gender and age had no significant difference. Conclusions These results indicate the local concentration of Ca2+ may be an indicator for the prognosis of THA patients.

The local concentration of Ca2+ correlates with BMP7 expression and osseointegration in patients with total hip arthroplasty

Background: A successful osseointegration of total hip arthroplasty (THA) relies on the interplay of implant surface and bone marrow microenvironment. This study was undertaken to investigate the impact of perioperative biochemical molecules (Ca2+, Mg2+, Zn2+, VD, PTH) on the bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells) in the metaphyseal region of the femoral head, and further on the bone mineral density (BMD) of Gruen R3. Methods: Bone marrow aspirates were obtained from the discarded metaphysis region of the femoral head in 51 patients with THA. Flow cytometry was used to measure the Stro-1+ expressing cells. ELISA was used to measure the concentrations of bone morphologic proteins (BMP2 and BMP7) and the content of TRACP5b in serum. TRAP staining was used to detect the osteoclast activity in the hip joint. The perioperative concentrations of the biochemical molecules above were measured by radioimmunoassay. The BMD of Gruen zone R3 was examined at 6 months after THA, using dual-energy X-ray absorptiometry (DEXA).Results: Our data demonstrated that the concentration of Ca2+ was positively correlated with BMP7 expression, and with the postoperative BMD of Gruen zone R3. However, the concentration of Mg2+ had little impact on the R3 BMD, although it was negatively correlated with the expression of BMP7. Osteoclast activity in hip joint tissue of patients with femoral neck fractures was increased. Compared with the patients before THA, the levels of TRACP5b in serum of patients after THA were decreased. The data also suggested that the other biochemical molecules, such as Zn2+, VD, and PTH, were not significantly correlated with any bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells). The postoperative R3 BMD of patients of different gender and age had no significant difference.Conclusions: These results indicate the local concentration of Ca2+ may be an indicator for the prognosis of THA patients.

Perioperative patient-specific factors-based nomograms predict short-term periprosthetic bone loss after total hip arthroplasty

Background Although medical intervention of periprosthetic bone loss in the immediate postoperative period was recommended, not all the patients experienced periprosthetic bone loss after total hip arthroplasty (THA). Prediction tools that enrolled all potential risk factors to calculate an individualized prediction of postoperative periprosthetic bone loss were strongly needed for clinical decision-making. Methods Data of the patients who underwent primary unilateral cementless THA between April 2015 and October 2017 in our center were retrospectively collected. Candidate variables included demographic data and bone mineral density (BMD) in spine, hip, and periprosthetic regions that measured 1 week after THA. Outcomes of interest included the risk of postoperative periprosthetic bone loss in Gruen zone 1, 7, and total zones in the 1st postoperative year. Nomograms were presented based on multiple logistic regressions via R language. One thousand Bootstraps were used for internal validation. Results Five hundred sixty-three patients met the inclusion criteria were enrolled, and the final analysis was performed in 427 patients (195 male and 232 female) after the exclusion. The mean BMD of Gruen zone 1, 7, and total were decreased by 4.1%, 6.4%, and 1.7% at the 1st year after THA, respectively. 61.1% of the patients (261/427) experienced bone loss in Gruen zone 1 at the 1st postoperative year, while there were 58.1% (248/427) in Gruen zone 7 and 63.0% (269/427) in Gruen zone total. Bias-corrected C-index for risk of postoperative bone loss in Gruen zone 1, 7, and total zones in the 1st postoperative year were 0.700, 0.785, and 0.696, respectively. The most highly influential factors for the postoperative periprosthetic bone loss were primary diagnosis and BMD in the corresponding Gruen zones at the baseline. Conclusions To the best of our knowledge, our study represented the first time to use the nomograms in estimating the risk of postoperative periprosthetic bone loss with adequate predictive discrimination and calibration. Those predictive models would help surgeons to identify high-risk patients who may benefit from anti-bone-resorptive treatment in the early postoperative period effectively. It is also beneficial for patients, as they can choose the treatment options based on a reasonable expectation following surgery.

Perioperative patient-specific factors-based nomograms predict short-term periprosthetic bone loss after total hip arthroplasty

Background: Although medical intervention of periprosthetic bone loss in the immediate postoperative period was recommended, not all the patients experienced periprosthetic bone loss after total hip arthroplasty (THA). Prediction tools that enrolled all potential risk factors to calculate an individualized prediction of postoperative periprosthetic bone loss were strongly needed for clinical decision-making. Methods: Data of the patients underwent primary unilateral cementless THA between April 2015 and October 2017 in our center were retrospectively collected. Candidate variables included demographic data and bone mineral density (BMD) in spine, hip and periprosthetic regions that measured 1 week after THA. Outcomes of interest included the risk of postoperative periprosthetic bone loss in Gruen zone 1, 7 and total zones in the 1st postoperative year. Nomograms were presented based on multiple logistic regressions via R language. 1000 Bootstraps were used for internal validation. Results: 563 patients met the inclusion criteria were enrolled, and the final analysis was performed in 427 patients (195 male and 232 female) after the exclusion. The mean BMD of Gruen zone 1, 7, and total were decreased by 4.1%, 6.4%, and 1.7% at the 1st year after THA, respectively. 61.1% of the patients (261/427) experienced bone loss in Gruen zone 1 at the 1st postoperative year, while there were 58.1% (248/427) in Gruen zone 7 and 63.0% (269/427) in Gruen zone total. Bias-corrected c-index for risk of postoperative bone loss in Gruen zone 1, 7 and total zones in the 1st postoperative year were 0.700, 0.785, and 0.696, respectively. The most highly influential factors for the postoperative periprosthetic bone loss were primary diagnosis and BMD in the corresponding Gruen zones at the baseline. Conclusions: To the best of our knowledge, our study represented the first time to use the nomograms in estimating the risk of postoperative periprosthetic bone loss with adequate predictive discrimination and calibration. Those predictive models would help surgeons to identify high-risk patients who may benefit from anti-bone-resorptive treatment on the early postoperative period effectively. It is also beneficial for patients, as they can choose the treatment options based on a reasonable expectation following surgery.

The local concentration of Ca2+ correlates with BMP7 expression and osseointegration in patients with total hip arthroplasty

Background: A successful osseointegration of total hip arthroplasty (THA) relies on the interplay of implant surface and bone marrow microenvironment. This study was undertaken to investigate the impact of perioperative biochemical molecules (Ca2+, Mg2+, Zn2+, VD, PTH) on the bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells) in the metaphyseal region of the femoral head, and further on the bone mineral density (BMD) of Gruen R3. Methods: Bone marrow aspirates were obtained from the discarded metaphysis region of the femoral head in 51 patients with THA. Flow cytometry was used to measure the Stro-1+ expressing cells. ELISA was used to measure the concentrations of bone morphologic proteins (BMP2 and BMP7). The perioperative concentrations of the biochemical molecules above were measured by radioimmunoassay. The BMD of Gruen zone R3 was examined at 6 months after THA, using dual-energy X-ray absorptiometry (DEXA).Results: Our data demonstrated that the concentration of Ca2+ was positively correlated with BMP7 expression, and with the postoperative BMD of Gruen zone R3. However, the concentration of Mg2+ had little impact on the R3 BMD, although it was negatively correlated with the expression of BMP7. The data also suggested that the other biochemical molecules, such as Zn2+, VD, and PTH, were not significantly correlated with any bone marrow osteogenetic factors (BMP2, BMP7, Stro-1+ cells). The postoperative R3 BMD of patients of different gender and age had no significant difference.Conclusions: These results indicate the local concentration of Ca2+ may be an indicator for the prognosis of THA patients.

Perioperative Patient-specific Factors-based Nomograms Predict Short-term Periprosthetic Bone Loss After Total Hip Arthroplasty

Background Although medical intervention of periprosthetic bone loss in the immediate postoperative period was recommended, not all the patients experienced periprosthetic bone loss after total hip arthroplasty (THA). Prediction toolsthat enrolledallpotential risk factors to calculate an individualized prediction of postoperative periprosthetic bone loss were strongly needed for clinical decision-making.MethodsData of the patients underwent primary unilateral cementless THA between April 2015 and October 2017 in our center were retrospectively collected. Candidate variables included demographic data and bone mineral density (BMD) in spine, hip and periprosthetic regions that measured 1 week after THA. Outcomes of interest included the risk of postoperative periprosthetic bone loss in Gruen zone 1, 7 and total zones in the 1st postoperative year. Nomograms were presented based on multiple logistic regressions via R language.Bootstrap was used for internal validation. Results 427 patients (195 male and 232 female) were included in this study.The mean BMD of Gruen zone 1, 7,and total were decreased by 4.1%, 6.4%, and 1.7% at the 1st year after THA, respectively. 61.1% of the patients (261/427) experienced bone loss in Gruen zone 1 at the 1st postoperative year, while there were 58.1% (248/427) in Gruen zone 7 and 63.0% (269/427) in Gruen zone total. Bias-corrected c-index for risk of postoperative bone lossin Gruen zone 1, 7 and total zones in the 1st postoperative year were 0.700, 0.785, and 0.696, respectively. The most highly influential factor for the postoperative periprosthetic bone loss was the BMD in the corresponding Gruen zones at the baseline.ConclusionsThe present study presented the perioperative factors-based nomograms for predicting periprosthetic bone loss after THA with adequate predictive discrimination and calibration.Those tools would helpsurgeons to identify high-risk patients who may benefit from anti-bone-resorptive treatment on the early postoperative period effectively. Such prediction model could also provide patients with reasonable expectations following surgery, which may improve satisfaction and patient compliance.