Hip Fracture in Patients With Non-Dialysis-Requiring Chronic Kidney Disease

Two Weeks of Continuous Opioid Treatment in an Adenine-Induced Mouse Model of Chronic Kidney Disease Exacerbates the Bone Inflammatory State and Increases Osteoclasts

Patients with chronic kidney disease (CKD) report high pain levels, but reduced renal clearance eliminates many analgesic options; therefore, 30-50% of CKD patients have chronic opioid prescriptions. Opioid use in CKD is associated with higher fracture rates. Opioids may directly alter bone turnover directly through effects on bone cells and indirectly via increasing inflammation. We hypothesized that continuous opioid exposure would exacerbate the high bone turnover state of CKD and be associated with elevated measures of inflammation. Male C57Bl/6J mice after 8 weeks of adenine-induced CKD (AD) and non-AD controls (CON) had 14-day osmotic pumps (0.25-µL/hr release) containing either saline or 50-mg/mL oxycodone (OXY) surgically implanted in the subscapular region. After 2 weeks, all AD mice had elevated blood urea nitrogen, parathyroid hormone, and serum markers of bone turnover compared to controls with no effect of OXY. Immunohistochemical staining of the distal femur showed increased numbers of osteocytes positive for the mu opioid and for toll-like receptor 4 (TLR4) due to OXY. Osteocyte protein expression of tumor necrosis factor-α (TNF-α) and RANKL were higher due to both AD and OXY so that AD + OXY mice had the highest values. Trabecular osteoclast-covered surfaces were also significantly higher due to both AD and OXY, resulting in AD + OXY mice having 4.5-fold higher osteoclast-covered surfaces than untreated CON. These data demonstrate that opioids are associated with a pro-inflammatory state in osteocytes which increases the pro-resorptive state of CKD.

Risk factors for hip and vertebral fractures in chronic kidney disease: the CRIC study

Fracture risk is high in chronic kidney disease (CKD) and underlying pathophysiology and risk factors may differ from the general population. In a cohort study of 3939 participants in the chronic renal insufficiency cohort (CRIC), we used Cox regression to test associations of putative risk factors with the composite of first hip or vertebral fracture assessed using hospital discharge codes. Mean age was 58 years, 45% were female, 42% were Black, and 13% were Hispanic. There were 82 hip and 24 vertebral fractures over a mean (SD) 11.1 (4.8) years (2.4 events per 1000 person-years [95% CI: 2.0, 2.9]). Measured at baseline, diabetes, lower body mass index (BMI), steroid use, proteinuria, and elevated parathyroid hormone (PTH) were each associated with fracture risk after adjusting for covariates. Lower time-updated estimated glomerular filtration rate (eGFR) was associated with fractures (HR 1.20 per 10 mL/min/1.73m2 lower eGFR; 95% CI: 1.04, 1.38) as were lower time-updated serum calcium and bicarbonate concentrations. Among time-updated categories of kidney function, hazard ratios (95% CI) for incident fracture were 4.53 (1.77, 11.60) for kidney failure treated with dialysis and 2.48 (0.86, 7.14) for post-kidney transplantation, compared with eGFR ≥60. Proton pump inhibitor use, dietary calcium intake, measures of vitamin D status, serum phosphate, urine calcium and phosphate, and plasma fibroblast growth factor-23 were not associated with fracture risk. In conclusion, lower eGFR in CKD is associated with higher fracture risk, which was highest in kidney failure. Diabetes, lower BMI, steroid use, proteinuria, higher serum concentrations of PTH, and lower calcium and bicarbonate concentrations were associated with fractures and may be modifiable risk factors.

Inhibition of RANKL improves the skeletal phenotype of adenine-induced chronic kidney disease in mice

Skeletal fragility and high fracture rates are common in CKD. A key component of bone loss in CKD with secondary hyperparathyroidism is high bone turnover and cortical bone deterioration through both cortical porosity and cortical thinning. We hypothesized that RANKL drives high bone resorption within cortical bone leading to the development of cortical porosity in CKD (study 1) and that systemic inhibition of RANKL would mitigate the skeletal phenotype of CKD (study 2). In study 1, we assessed the skeletal properties of male and female Dmp1-cre RANKLfl/fl (cKO) and control genotype (Ranklfl/fl; Con) mice after 10 wk of adenine-induced CKD (AD; 0.2% dietary adenine). All AD mice regardless of sex or genotype had elevated blood urea nitrogen and high PTH. Con AD mice in both sexes had cortical porosity and lower cortical thickness as well as high osteoclast-covered trabecular surfaces and higher bone formation rate. cKO mice had preserved cortical bone microarchitecture despite high circulating PTH as well as no CKD-induced increases in osteoclasts. In study 2, male mice with established AD CKD were either given a single injection of an anti-RANKL antibody (5 mg/kg) 8 wk post-induction of CKD or subjected to 3×/wk dosing with risedronate (1.2 μg/kg) for 4 wk. Anti-RANKL treatment significantly reduced bone formation rate as well as osteoclast surfaces at both trabecular and cortical pore surfaces; risedronate treatment had little effect on these bone parameters. In conclusion, these studies demonstrate that bone-specific RANKL is critical for the development of high bone formation/high osteoclasts and cortical bone loss in CKD with high PTH. Additionally, systemic anti-RANKL ligand therapy in established CKD may help prevent the propagation of cortical bone loss via suppression of bone turnover.

Poor prognosis and risk factors of nonoperative treatment hip fracture patients with end-stage renal disease

This study aims to summarize the prognosis and risk factors of nonoperative treatment patients of hip fracture with end-stage renal disease (ESRD). A total of 113 individuals of hip fracture with nonoperative treatment were retrospectively enrolled, 38 patients with ESRD were defined as the observation group, and the other 75 patients without ESRD were served as the control group. The difference in 30-day and 1-year mortality rate between the 2 groups was compared. The effects of risk factors on survival were estimated by the Cox proportional-hazards model. The survival difference was estimated by the method of Kaplan-Meier. In the subsequent subgroup analysis of the observation group, as before, the Cox proportional-hazards model and the Kaplan-Meier method were used. The 1-year mortality rate of the observation group was considerably higher than that of the control group, which was 86.84% and 32.0%, respectively (P < .005). For nonoperative treatment hip fracture subjects, ESRD, age ≥ 82, BMI (BMI) < 20, high Charlson Comorbidity Index (CCI) and low Barthel Index (BI) were associated with a low survival curve (P < .05). In the subsequent multivariable subgroup analyses, for nonoperative treatment hip fracture subjects with ESRD, high CCI and low BI were also the independent risk factors of mortality. For nonoperative treatment hip fracture subjects, ESRD, old age, low BMI, high CCI and low BI were the independent risk factors of mortality. For hip fracture subjects with ESRD, nonoperative treatment was associated with excess high 1-year mortality rate, especially for patients with high CCI and low BI.

Low muscle strength and physical function contribute to falls in hemodialysis patients, but not muscle mass

INTRODUCTION

Patients on hemodialysis (HD) have a higher incidence of fractures than the general population. Sarcopenia is frequently observed in patients on HD; however, the association of falls with sarcopenia and its diagnostic factors, including muscle mass, muscle strength, and physical function, are incompletely understood.

METHODS

This prospective cohort study was conducted at a single center. Sarcopenia was assessed according to the 2019 Asian Working Group for Sarcopenia diagnostic criteria. Muscle mass was measured the bioelectrical impedance method. Grip strength was evaluated to assess muscle strength, while the Short Physical Performance Battery (SPPB) was used to assess physical function. Falls and their detailed information were surveyed every other week.

RESULTS

This study analyzed 65 HD patients (median age, 74.5 [67.5-80.0] years; 33 women [49.2%]). Sarcopenia was diagnosed in 36 (55.4%) patients. During the 1-year observation period, 31 (47.7%) patients experienced accidental falls. The falls group had lower median grip strength than the non-falls group (14.7 [11.4-21.8] kg vs. 22.2 [17.9-27.6] kg; p < 0.001). The median SPPB score was also lower in the falls versus non-falls group (7.0 [5.0-11.0] vs. 11.0 [8.0-12.0]; p = 0.009). In adjusted multiple regression analysis, diagnostic factors, including grip strength (B = 0.96, p = 0.04, R2 = 0.19) and SPPB (B = 1.11, p = 0.006, R2 = 0.23), but not muscle mass, were independently associated with fall frequency.

CONCLUSIONS

The frequency of falls in HD patients was related to muscle strength and physical function, but not muscle mass.

Changes in Bone Quality after Treatment with Etelcalcetide

INTRODUCTION

Secondary hyperparathyroidism is associated with osteoporosis and fractures. Etelcalcetide is an intravenous calcimimetic for the control of hyperparathyroidism in patients on hemodialysis. Effects of etelcalcetide on the skeleton are unknown.

METHODS

In a single-arm, open-label, 36-week prospective trial, we hypothesized that etelcalcetide improves bone quality and strength without damaging bone-tissue quality. Participants were 18 years or older, on hemodialysis ≥1 year, without calcimimetic exposure within 12 weeks of enrollment. We measured pretreatment and post-treatment areal bone mineral density by dual-energy X-ray absorptiometry, central skeleton trabecular microarchitecture by trabecular bone score, and peripheral skeleton volumetric bone density, geometry, microarchitecture, and estimated strength by high-resolution peripheral quantitative computed tomography. Bone-tissue quality was assessed using quadruple-label bone biopsy in a subset of patients. Paired t tests were used in our analysis.

RESULTS

Twenty-two participants were enrolled; 13 completed follow-up (mean±SD age 51±14 years, 53% male, and 15% White). Five underwent bone biopsy (mean±SD age 52±16 years and 80% female). Over 36 weeks, parathyroid hormone levels declined 67%±9% ( P < 0.001); areal bone mineral density at the spine, femoral neck, and total hip increased 3%±1%, 7%±2%, and 3%±1%, respectively ( P < 0.05); spine trabecular bone score increased 10%±2% ( P < 0.001); and radius stiffness and failure load trended to a 7%±4% ( P = 0.05) and 6%±4% increase ( P = 0.06), respectively. Bone biopsy demonstrated a decreased bone formation rate (mean difference -25±4 µ m 3 / µ m 2 per year; P < 0.01).

CONCLUSIONS

Treatment with etelcalcetide for 36 weeks was associated with improvements in central skeleton areal bone mineral density and trabecular quality and lowered bone turnover without affecting bone material properties.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

The Effect of Etelcalcetide on CKD-MBD (Parsabiv-MBD), NCT03960437.

Angiotensin II receptor blockers and bone fracture in chronic kidney disease patients: the Fukuoka kidney disease Registry Study

BACKGROUND

Angiotensin II receptor blockers (ARBs) reportedly reduce the risk of developing bone fractures; however, this association remains unclear among patients with chronic kidney disease (CKD).

METHODS

This was a cross-sectional study of 3380 CKD patients enrolled in the Fukuoka Kidney disease Registry Study, a multicenter prospective observational cohort study of non-dialysis-dependent CKD patients. The patients were divided into two groups, those taking ARBs and those who were not. Logistic regression models were used to examine the association between ARBs and bone fracture.

RESULTS

Approximately 67.0% of the participants were on ARBs, and 6.3% had a history of bone fracture. The history of bone fracture was significantly lower in patients with prescribed ARB and remained significant even after multivariable adjustment (odds ratio, 0.68; 95% confidence interval, 0.51-0.93). Other antihypertensive drugs, such as thiazide diuretics, which were reportedly helpful in preventing fractures, did not alter the bone fracture history and did not change among ARB users and non-users.

CONCLUSIONS

The present study showed that administering ARB was significantly associated with a lower frequency of bone fracture history.

Functional Outcomes After High-Energy Lisfranc Injuries

BACKGROUND

Midfoot fractures and dislocations are infrequent and functional outcomes following Lisfranc injuries have not been well described. The purpose of this project was to explore functional outcomes following operative treatment of high-energy Lisfranc injury.

METHODS

A retrospective cohort of 46 adults with tarsometatarsal fractures and dislocations treated at a single Level 1 trauma center were reviewed. Demographic, medical, social, and injury features of these patients and their injuries were recorded. Foot Function Index (FFI) and Short Musculoskeletal Function Assessment (SMFA) surveys were collected after mean 8.7 years' follow-up. Multiple linear regression was performed to identify independent predictors of outcome.

RESULTS

Forty-six patients with mean age 39.7 years completed functional outcome surveys. Mean SMFA scores were 29.3 (dysfunction) and 32.6 (bothersome). Mean FFI scores were 43.1 (pain), 43.0 (disability), and 21.7 (activity), with a mean total score of 35.9. FFI pain scores were worse than published values for fractures of the plafond (33, P = .04), distal tibia (33, P = .04), and talus (25.3, P = .001). Lisfranc injury patients reported worse disability (43.0 vs 29, P = .008) and total FFI scores (35.9 vs 26, P = .02) compared with distal tibia fractures. Tobacco smoking was an independent predictor of worse FFI (P < .05) and SMFA emotion and bothersome scores (P < .04). Chronic renal disease was a predictor of worse FFI disability (P = .04) and SMFA subcategory scores (P < .04). Male sex was associated with better scores in all SMFA categories (P < .04). Age, obesity, or open injury did not affect functional outcomes.

CONCLUSION

Patients reported worse pain by FFI after Lisfranc injury compared to other injuries about the foot and ankle. Tobacco smoking, female sex, and preexisting chronic renal disease are predictive of worse functional outcome scores, warranting further study in a larger sample, as well as counseling of long-term consequences of this injury.

LEVEL OF EVIDENCE

Level IV, retrospective, prognostic.

Efficacy and safety of medications for osteoporosis in kidney transplant recipients or patients with chronic kidney disease: A meta-analysis

This study conducted a meta-analysis to analyze the efficacy and safety of osteoporosis medications in kidney transplant recipients and patients with chronic kidney disease (CKD). PubMed, Embase, the Cochrane Central Register of Controlled Trials were searched from the date of their inception through October 21, 2022. We performed a meta-analysis of the efficacy and safety of osteoporosis medications in adult patients with stage 3-5 CKD or kidney transplant recipients enrolled in randomized clinical trials (RCTs). We calculated the standard mean deviations with 95% confidence intervals (CI) for bone mineral density (BMD) and T scores after 6 and 12 months treatment, pooled odds ratio and 95% CI for fracture risk, and summarized adverse events. The inclusion criteria were met by 27 studies. Out of this, 19 studies were included for the meta-analysis. In stage 3-4 CKD patients, alendronate increased lumbar spine BMD. In patients at stage 5 CKD and undergoing hemodialysis, alendronate and raloxifene increased lumbar spine BMD. After 6 months, the BMD of kidney transplant recipients was seen to be significantly increased; however, there was no difference after 12 months, and the risk of fracture did not reduce. Thus, there is no evidence that these medications reduce the risk of fracture, and their effect on BMD and fracture remains unproven. These medications may increase the incidence of adverse events and their safety needs to be further evaluated. Therefore, we cannot draw a definitive conclusion about the efficacy and safety of osteoporosis medications in the above group of patients.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Current Status of Mineral and Bone Disorders in Transplant Recipients

Most patients with end-stage kidney disease undergoing kidney transplantation are affected by the chronic kidney disease-mineral and bone disorder. This entity encompasses laboratory abnormalities, calcification of soft tissues, and the bone abnormalities of renal osteodystrophy that together result in an increased risk of fracture, cardiovascular events, and mortality. Although many biochemical disturbances associated with end-stage kidney disease improve in the first year after transplantation, hyperparathyroidism commonly persists, and residual changes of renal osteodystrophy are slow to resolve. When superimposed on common, traditional risk factors, post-transplant glucocorticoid treatment, the possibility of tubular disturbances and post-transplant chronic kidney disease, rates of incident fracture remain high. This review examines hormonal and biochemical changes before and after kidney transplantation, fracture risk assessment tools and imaging modalities, a staged approach to management and concerns associated with antiresorptive and anabolic therapies. A multidisciplinary approach is proposed as the best means to improve patient-level outcomes.

Transcription factor HNF4α2 promotes osteogenesis and prevents bone abnormalities in mice with renal osteodystrophy

Renal osteodystrophy (ROD) is a disorder of bone metabolism that affects virtually all patients with chronic kidney disease (CKD) and is associated with adverse clinical outcomes including fractures, cardiovascular events, and death. In this study, we showed that hepatocyte nuclear factor 4α (HNF4α), a transcription factor mostly expressed in the liver, is also expressed in bone, and that osseous HNF4α expression was dramatically reduced in patients and mice with ROD. Osteoblast-specific deletion of Hnf4α resulted in impaired osteogenesis in cells and mice. Using multi-omics analyses of bones and cells lacking or overexpressing Hnf4α1 and Hnf4α2, we showed that HNF4α2 is the main osseous Hnf4α isoform that regulates osteogenesis, cell metabolism, and cell death. As a result, osteoblast-specific overexpression of Hnf4α2 prevented bone loss in mice with CKD. Our results showed that HNF4α2 is a transcriptional regulator of osteogenesis, implicated in the development of ROD.

Comprehensive Associations between Acidosis and the Skeleton in Patients with Kidney Disease

SIGNIFICANCE STATEMENT

Renal osteodystrophy (ROD) contributes substantially to morbidity in CKD, including increased fracture risk. Metabolic acidosis (MA) contributes to the development of ROD, but an up-to-date skeletal phenotype in CKD-associated acidosis has not been described. We comprehensively studied associations between acidosis and bone in patients with CKD using advanced methods to image the skeleton and analyze bone-tissue, along with biochemical testing. Cross-sectionally, acidosis was associated with higher markers of bone remodeling and female-specific impairments in cortical and trabecular bone quality. Prospectively, acidosis was associated with cortical expansion and trabecular microarchitectural deterioration. At the bone-tissue level, acidosis was associated with deficits in bone mineral content. Future work investigating acidosis correction on bone quality is warranted.

BACKGROUND

Renal osteodystrophy is a state of impaired bone quality and strength. Metabolic acidosis (MA) is associated with alterations in bone quality including remodeling, microarchitecture, and mineralization. No studies in patients with CKD have provided a comprehensive multimodal skeletal phenotype of MA. We aim to describe the structure and makeup of bone in patients with MA in the setting of CKD using biochemistry, noninvasive imaging, and histomorphometry.

METHODS

The retrospective cross-sectional analyses included 180 patients with CKD. MA was defined as bicarbonate ≤22 mEq/L. We evaluated circulating bone turnover markers and skeletal imaging with dual energy x-ray absorptiometry and high-resolution peripheral computed tomography. A subset of 54 participants had follow-up. We assessed associations between baseline and change in bicarbonate with change in bone outcomes. Histomorphometry, microCT, and quantitative backscatter electron microscopy assessed bone biopsy outcomes in 22 participants.

RESULTS

The mean age was 68±10 years, 54% of participants were male, and 55% were White. At baseline, acidotic subjects had higher markers of bone turnover, lower areal bone mineral density at the radius by dual energy x-ray absorptiometry, and lower cortical and trabecular volumetric bone mineral density and impaired trabecular microarchitecture. Over time, acidosis was associated with opposing cortical and trabecular effects: cortical expansion but trabecular deterioration. Bone-tissue analyses showed reduced tissue mineral density with increased heterogeneity of calcium distribution in acidotic participants.

CONCLUSIONS

MA is associated with multiple impairments in bone quality. Future work should examine whether correction of acidosis improves bone quality and strength in patients with CKD.

Impaired renal function is an independent risk factor for complications after surgery for femoral neck fracture

BACKGROUND

The metabolic abnormalities that occur secondary to chronic kidney disease (CKD) increase the risk of femoral neck fractures compared to the general population. The purpose of this study is to determine whether impaired renal function is an independent risk factor for complications after surgery for femoral neck fracture.

METHODS

The ACS-NSQIP database was reviewed for patients who underwent total hip arthroplasty, hemiarthroplasty and open reduction internal fixation (ORIF) for femoral neck fractures between 2007 and 2018. Patients were split into cohorts based on calculated estimated glomerular filtration rate. Demographic information, comorbidities, and 30-day complications were analysed with univariate and multivariate analyses using chi-square, Fischer's exact and analysis of variance testing.

RESULTS

The total number of patients for the study was 163,717. Patients with CKD stage 4 and 5 had an increased rate of any complication (39.1 and 36.7% respectively) compared with higher eGFRs (p < 0.001). Similarly, 30-day mortality was increased at 6.0% and 6.7% for both stage 4 and 5 (p < 0.001). By multivariate regression, those with CKD Stage 4 and 5 were at increased risk for any complication compared to patients with a normal preoperative eGFR of 90-120 (p < 0.001).

CONCLUSIONS

This study demonstrated that patients with CKD Stage 4 and 5 are at increased risks of all complications, including death, renal, pulmonary and thromboembolic disease. Therefore, these patients should be cared for from a multidisciplinary approach with close attention to postoperative medications and fall prevention to help mitigate the risk of complications in the immediate postoperative period.

Association of Chronic Kidney Disease and Complications Following Acute Torsional Ankle Fracture

BACKGROUND

Although chronic kidney disease (CKD) has been associated with poor outcomes following traumatic fractures, there is a scarcity of literature describing the effect on outcomes of ankle fractures. We will examine the impact of CKD on clinical outcomes following torsional ankle fracture, including complications and unplanned surgical procedures.

METHODS

A retrospective review of 1981 adult patients with torsional ankle fractures treated at a level 1 trauma center was performed to identify patients with CKD based on glomerular filtration rate. Demographic, injury, and treatment-related characteristics were collected. Outcomes included any unplanned procedure: implant removal, debridement, revision, arthrodesis, and amputation; in addition to complications of superficial infection, deep infection, and implant irritation. Patients with CKD were matched with patients without CKD by propensity score matching. Univariate comparisons between groups were conducted using chi-square and Mann-Whitney U tests.

RESULTS

136 patients (68 with CKD and 68 without CKD) were analyzed. Of the 68 patients with CKD, the mean stage of disease was 3.7 with 24% on dialysis for a mean length of 4.1 years. Patients without CKD were more likely to undergo primary ORIF (100% vs 54%, P < .001). Thirty-five percent of patients with CKD had surgical complications vs 19% in the cohort without (P = .07). Patients with open fractures, dislocation, and chronic kidney disease were, respectively, 5.19, 3.77, and 3.91 times more likely to have any complication (P = .02, P = .05, P = .05). Patients with CKD were more likely to undergo unplanned arthrodesis (P = .01). Only dislocation was an independent predictor for unplanned procedure (odds ratio = 5.08, P = .026).

CONCLUSION

Following torsional ankle fracture, CKD is associated with increased likelihood of having a complication or an unplanned arthrodesis. Open fractures and dislocation at time of injury are also associated with complications. Our findings encourage caution about surgical treatment of ankle fractures in patients with CKD.

LEVEL OF EVIDENCE

Level III, retrospective, comparative, prognostic.

Cortical porosity occurs at varying degrees throughout the skeleton in rats with chronic kidney disease

Cortical porosity develops in chronic kidney disease (CKD) and increases with progressing disease. Cortical porosity is likely a prominent contributor to skeletal fragility/fracture. The degree to which cortical porosity occurs throughout the skeleton is not fully known. In this study, we assessed cortical bone porosity via micro-computed tomography at multiple skeletal sites in rats with progressive chronic kidney disease. We hypothesized that cortical porosity would occur in long bones throughout the body, but to a lesser degree in flat bones and irregular bones. Porosity was measured, using micro-CT, at 17 different skeletal sites in 6 male rats with CKD. Varying degrees of porosity were seen throughout the skeleton with higher porosity in flat and irregular bone (i.e. parietal bone, mandible) vs. long bones (p = 0.01) and in non-weightbearing bones vs. weightbearing bones (p = 0.01). Porosity was also higher in proximal sites vs. distal sites in long bones (p < 0.01 in all comparisons). There was large heterogeneity in porosity within skeletal sites across rats and within the same rat across skeletal sites. Correlations showed cortical porosity of the proximal tibia was positively associated with porosity at the other sites with the strongest correlation to the parietal bone and the weakest to the ulna. Overall, our data demonstrates varying and significant cortical bone porosity across the skeleton of animals with chronic kidney disease. These data point to careful selection of skeletal sites to assess porosity in pre-clinical studies and the potential for fractures at multiple skeletal sites in patients with CKD.

25-OH vitamin D threshold for optimal bone mineral density in elderly patients with chronic kidney disease

Introduction: Vitamin D deficiency is common in chronic kidney disease (CKD) and is associated with lower bone mineral density (BMD), decreased muscle strength, and increased hip fracture risk. Guidelines have suggested targeting 25-OH vitamin D (25(OH)D) levels between 20 and 30 ng/ml. However, vitamin D metabolism is altered in CKD, and threshold levels for optimal BMD are unknown. Methods: We included 1097 patients with hip fractures. CKD was defined as estimated glomerular filtration rate <60 ml/min/1.73 m (Mucsi et al., Clin. Nephrol., 2005, 64(4), 288-294) and low BMD defined as T score ≤ -2.5 at femoral neck. We assessed the association of 25(OH)D with low BMD in patients with and without CKD: using the conventional threshold 25(OH)D < 30 ng/dl, as well as a new threshold. Results: CKD was present in 479 (44%) patients. Using a threshold of 25(OH)D < 30 ng/ml, there were no significant differences in patients with CKD and low BMD when compared to the other groups. We identified 27 ng/ml as a better threshold with the Youden index. Using 25(OH)D < 27 ng/ml as a threshold, 360 of 482 patients (74.7%) with low 25(OH)D had low BMD, compared to only 185/276 (67%) of patients with adequate vitamin D, p = 0.02, which was irrespective of the presence or absence of CKD. Furthermore, patients with CKD and 25(OH)D < 27 ng/ml had a higher odds ratio of mortality upon follow-up, 1.61, 95% CI: 1.08-2.39, compared to those with CKD and 25(OH)D ≥ 27 ng/ml. Conclusion: We find that 25(OH)D < 27 ng/ml is associated with low BMD in patients with and without CKD. Further prospective studies targeting vitamin D repletion to at least 27 ng/ml and the outcome of hip fractures will be useful to validate these findings.

Association between cause of kidney failure and fracture incidence in a national US dialysis population cohort study

Background

Whether fracture rates, overall and by fracture site, vary by cause of kidney failure in patients receiving dialysis is unknown.

Methods

Using the US Renal Data System, we compared fracture rates across seven causes of kidney failure in patients who started dialysis between 1997 and 2014. We computed unadjusted and multivariable adjusted proportional sub-distribution hazard models, with fracture events (overall, and by site) as the outcome and immunoglobulin A nephropathy as the reference group. Kidney transplantation and death were competing events.

Results

Among 491 496 individuals, with a median follow-up of 2.0 (25%, 75% range 0.9–3.9) years, 62 954 (12.8%) experienced at least one fracture. Patients with diabetic nephropathy, vasculitis or autosomal polycystic kidney disease (ADPKD) had the highest (50, 46 and 40 per 1000 person-years, respectively), and patient with lupus nephritis had the lowest (20 per 1000 person-years) fracture rates. After multivariable adjustment, diabetic nephropathy [hazard ratio (HR) 1.43, 95% confidence interval 1.33–1.53], ADPKD (HR 1.37, 1.26–1.48), vasculitis (HR 1.22, 1.09–1.34), membranous nephropathy (HR 1.16, 1.02–1.30) and focal segmental glomerulosclerosis (FSGS) (HR 1.13, 1.02–1.24) were associated with a significantly higher, and lupus nephritis with a significantly lower (HR 0.85, 0.71–0.98) fracture hazard. The hazards for upper extremity and lower leg fractures were significantly higher in diabetic nephropathy, ADPKD, FSGS and membranous nephropathy, while the hazard for vertebral fracture was significantly higher in vasculitis. Our findings were limited by the lack of data on medication use and whether fractures were traumatic or non-traumatic, among other factors.

Conclusions

Fracture risk, overall and by fracture site, varies by cause of end-stage kidney disease. Future work to determine underlying pathogenic mechanisms contributing to differential risks might inform more tailored treatment strategies. Our study was limited by lack of data regarding numerous potential confounders or mediators including medications and measures or bone biomarkers.

Chemical evidence for the tradeoff-in-the-nephron hypothesis to explain secondary hyperparathyroidism

Background

Secondary hyperparathyroidism (SHPT) complicates advanced chronic kidney disease (CKD) and causes skeletal and other morbidity. In animal models of CKD, SHPT was prevented and reversed by reduction of dietary phosphate in proportion to GFR, but the phenomena underlying these observations are not understood. The tradeoff-in-the-nephron hypothesis states that as GFR falls, the phosphate concentration in the distal convoluted tubule ([P]_DCT]) rises, reduces the ionized calcium concentration in that segment ([Ca⁺⁺]_DCT), and thereby induces increased secretion of parathyroid hormone (PTH) to maintain normal calcium reabsorption. In patients with CKD, we previously documented correlations between [PTH] and phosphate excreted per volume of filtrate (E_P/C_cr), a surrogate for [P]_DCT. In the present investigation, we estimated [P]_DCT from physiologic considerations and measurements of phosphaturia, and sought evidence for a specific chemical phenomenon by which increased [P]_DCT could lower [Ca⁺⁺]_DCT and raise [PTH].

Methods and findings

We studied 28 patients (“CKD”) with eGFR of 14–49 mL/min/1.73m² (mean 29.9 ± 9.5) and 27 controls (“CTRL”) with eGFR > 60 mL/min/1.73m² (mean 86.2 ± 10.2). In each subject, total [Ca]_DCT and [P]_DCT were deduced from relevant laboratory data. The Joint Expert Speciation System (JESS) was used to calculate [Ca⁺⁺]_DCT and concentrations of related chemical species under the assumption that a solid phase of amorphous calcium phosphate (Ca₃(PO₄)₂ (am., s.)) could precipitate. Regressions of [PTH] on eGFR, [P]_DCT, and [Ca⁺⁺]_DCT were then examined. At filtrate pH of 6.8 and 7.0, [P]_DCT was found to be the sole determinant of [Ca⁺⁺]_DCT, and precipitation of Ca₃(PO₄)₂ (am., s.) appeared to mediate this result. At pH 6.6, total [Ca]_DCT was the principal determinant of [Ca⁺⁺]_DCT, [P]_DCT was a minor determinant, and precipitation of Ca₃(PO₄)₂ (am., s.) was predicted in no CKD and five CTRL. In CKD, at all three pH values, [PTH] varied directly with [P]_DCT and inversely with [Ca⁺⁺]_DCT, and a reduced [Ca⁺⁺]_DCT was identified at which [PTH] rose unequivocally. Relationships of [PTH] to [Ca⁺⁺]_DCT and to eGFR resembled each other closely.

Conclusions

As [P]_DCT increases, chemical speciation calculations predict reduction of [Ca⁺⁺]_DCT through precipitation of Ca₃(PO₄)₂ (am., s.). [PTH] appears to rise unequivocally if [Ca⁺⁺]_DCT falls sufficiently. These results support the tradeoff-in-the-nephron hypothesis, and they explain why proportional phosphate restriction prevented and reversed SHPT in experimental CKD. Whether equally stringent treatment can be as efficacious in humans warrants investigation.

Dysfunction in dynamic, but not static balance is associated with risk of accidental falls in hemodialysis patients: a prospective cohort study

Background

Patients with chronic kidney disease undergoing hemodialysis (HD) have a high incidence of falls. Impairment of balance function is a risk factor for falls in the general elderly, and no report examining the association between balance dysfunction and fall incidence in HD patients exists.

Methods

This prospective cohort study was conducted at a single center. The timed-up-and-go test (TUG) as a dynamic balance function was performed and length of the center of pressure (CoP) as a static balance function was measured before and after the HD session at baseline. Data of the number and detailed information of accidental falls for 1 year were collected. Multiple regression analyses were performed to assess the relationships between the number of falls and balance function.

Results

Forty-three patients undergoing HD were enrolled in the study. During 1 year of observation, 24 (55.8%) patients experienced accidental falls. TUG time was longer, and CoP was shorter in the post-HD session than in the pre-HD session. Adjusted multiple regression analyses showed that the number of accidental falls was independently associated with TUG time in the pre-HD session (B 0.267, p < 0.001, R² 0.413) and that in the post-HD session (B 0.257, p < 0.001, R² 0.530), but not with CoP.

Conclusions

Dynamic balance was associated with fall incidence in maintenance HD patients. The evaluation and intervention of dynamic balance function might reduce the risk of falls in HD patients.

Trial registration

This study was carried out with the approval of the Niigata Rinko Hospital Ethics Committee (approval number 2005–92) (Registered on December 11, 2019) and registered in The University Hospital Medical Information Network (registration number 000040618).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02877-6.

The effect of CKD on intertrochanteric fracture treated with proximal femoral nail anti-rotation: A 7-year study

Background

Intertrochanteric fracture is one of the most burdensome osteoporotic fractures in the elderly. Chronic kidney disease is associated with sarcopenia, especially in its advanced stages and, thus may impact functional status. Combining an intertrochanteric fracture with advanced CKD may diminish results after surgical fixation. This study aims to distinguish whether CKD affects the result of intertrochanteric fracture fixation in terms of mechanical and functional outcomes.

Methods

A retrospective study reviews all intertrochanteric fractures treated with PFNA fixation from 2012 to 2018. 445 patients were classified into 5 stages of CKD and divided by eGFR = 90 ml/min/1.73 m² into CKD and non-CKD group and by eGFR = 30 ml/min/1.73 m² into advanced CKD and non-advanced CKD group. The primary outcome was one year Harris Hip Score (HHS). Secondary outcomes were medical complications, surgical complications, and a 1-year mortality rate.

Results

Harris Hip Scores (HHS) were not different between non-CKD and CKD groups (eGFR <90 mL/min/1.73 m²). However, there was a difference between non-advanced CKD and advanced CKD groups (eGFR <30 mL/min/1.73 m²) (p < 0.001). Medical complications were not different, except for sepsis in CKD stage 5 compared with stage 1 (p = 0.023). Even though AO/OTA types were more severe in the advanced CKD group, surgical complications and 1-year mortality were not different.

Conclusion

Advanced stage CKD treated with PFNA fixation is associated with lower functional outcomes at one year. Sepsis is more prone to occur after surgery in CKD stage 5.

Level of evidence

Level III; Retrospective cohort study.

Magnesium exposure increases hip fracture risks in patients with chronic kidney disease: a population-based nested case-control study

This population-based study demonstrates a strong link between Mg-containing antacid exposure and hip fracture risk in nondialysis CKD and dialysis patients. As an Mg-containing antacid, MgO is also commonly used as a stool softener, which can be effortlessly replaced by other laxatives in CKD patients to maintain bone health.

PURPOSE

Bone fracture is a severe complication in chronic kidney disease (CKD) patients, leading to disability and reduced survival. In CKD patients, blood magnesium (Mg) concentrations are usually above the normal range due to reduced kidney excretion of Mg. The present study examines the association between Mg-containing antacid exposure and the risk of hip fracture of CKD patients.

METHODS

In this nationwide nested case-control study, we enrolled 44,062 CKD patients with hip fracture and 44,062 CKD matched controls, among which the mean age was 77.1 years old, and 87.9% was nondialysis CKD.

RESULTS

As compared to non-users, Mg-containing antacid users were significantly more likely to experience hip fracture (adjusted odds ratio (OR) 1.36, 95% CI, 1.32 to 1.41; p < 0.001). Subgroup analysis showed that such risk exists in both nondialysis CKD patients and long-term dialysis patients. In contrast, aluminum or calcium-containing-antacid use did not reveal such association. Next, we examined the influence of Mg-containing antacid dosage on hip fracture risk, the adjusted ORs in the first quartile (Q1), Q2, Q3, and Q4 were 1.20 (95% CI, 1.15 to 1.25; p < 0.001), 1.35 (95% CI, 1.30 to 1.41; p < 0.001), 1.49 (95% CI, 1.43 to 1.56; p < 0.001), and 1.54 (95% CI, 1.47 to 1.61; p < 0.001), respectively, showing that such risk exists regardless of the antacid dosage. A receiver operating characteristic curve analysis demonstrated that the best cutoff value of the exposed Mg dose to discriminate the hip fracture is 532 mEq during the follow-up period.

CONCLUSION

This population-based study demonstrates a strong link between Mg-containing antacid exposure and the hip fracture risk in both nondialysis CKD and dialysis patients.

Cortical porosity development and progression is mitigated after etelcalcetide treatment in an animal model of chronic kidney disease

PURPOSE

Chronic kidney disease (CKD) leads to increased bone fragility and risk of fracture. Cortical deteriorations, including cortical porosity, are key factors in fracture susceptibility in CKD. Since secondary hyperparathyroidism is common in CKD individuals and contributes to cortical deterioration, we hypothesized that reducing parathyroid hormone (PTH) may modulate CKD-induced cortical porosity. The goal of this pilot study was to assess the effects of lowering PTH, via the preclinical analogue of the FDA-approved calcimimetic etelcalcetide (KP-2326), on the development and progression of cortical pores in the setting of CKD.

METHODS

Male Cy/+ Sprague Dawley rats with clinical biochemistries consistent with CKD (N = 8) were assigned to the study. At 30-32 weeks of age, cortical bone was assessed via In vivo μCT and blood collected for biochemistries to create baseline measures. Calcimimetic treatment with KP-2326 (KP) was then administered 3× weekly for 2-4 weeks. Cortical bone and biochemical parameters were repeated at study endpoint (33-37 wks of age). A group of age- and cohort-matched CKD rats (N = 4) were utilized as untreated controls.

RESULTS

Untreated CKD rats had significantly increased cortical porosity over time, while porosity in KP-treated CKD rats was not significantly changed over time. Individual pore analysis revealed that pore area was significantly higher for expanding pores in untreated CKD rats compared to KP-treated CKD rats. Mechanical properties of KP-treated animal femora were similar to historical values of age-matched CKD animals and lower than those of age-matched non-diseased animals.

CONCLUSION

Our pilot preclinical study demonstrates that etelcalcetide treatment can mitigate the progression of cortical bone changes in an animal model of CKD through suppression of pre-existing cortical pore expansion and limiting the size of new pore development. While stabilization of porosity is beneficial it remains likely that infilling of porosity will be needed to positively affect mechanical properties of bones in the setting of CKD.

Chronic kidney disease and risk of postoperative cardiovascular events in elderly patients receiving hip fracture surgery

INTRODUCTION

The long-term risk of cardiovascular events caused by chronic kidney disease (CKD) is well described in the general population. Less is known concerning the risk of postoperative cardiovascular events in geriatric hip fracture patients with CKD.

METHODS

This study involved patients at least 65 years of age who received surgery for acute hip fracture between January 2000 and April 2016. We identified CKD patients with a baseline diagnosis of CKD or an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² at admission. Each CKD patient was matched, for age, gender, fracture type, and year of admission, with 4 control non-CKD patients. The primary endpoint was a compositepostoperative cardiovascular events, including pulmonary embolism, angina pectoris, myocardial infarction, heart failure, arrhythmia, stroke, and death. Conditional logistic regression was used to evaluate the association between CKD and the outcome after adjusting for potential confounders including age, gender, fracture type, body mass index, preexisting comorbidities, history of cardiovascular events, and the Charlson Comorbidity Index (CCI).

RESULTS

Three hundred and seventy-five CKD patients were matched with 1,438 non-CKD patients. The mean age of the CKD patients was 81.9 ± 7.0 (mean ± SD), 69.9% were females, and 59.2% had an intertrochanteric fracture. Compared to non-CKD patients, CKD patients had a higher proportion of preexisting comorbidities, including hypertension, coronary heart disease, heart failure, and type 2 diabetes (all p < 0.05). The risk of postoperative cardiovascular events was 125.3 per 1000 persons (95%CI, 91.8-158.8) in CKD patients and 64.7 per 1000 persons (95%CI, 52.0-77.4) in non-CKD patients. A 1.96-fold risk of cardiovascular events after hip fracture surgery was found in CKD patients than those without CKD (adjusted OR, 1.96; 95%CI, 1.23-3.12).

CONCLUSION

Patients with CKD were more likely to have cardiovascular events after hip fracture surgery than those without CKD. Appropriate preoperative cardiovascular risk assessment and corresponding preventive and therapeutic measures should be given to this vulnerable population to mitigate such complications.

Kidney Function Change and All-Cause Mortality in Denosumab Users with and without Chronic Kidney Disease

Denosumab is approved for osteoporosis treatment in subjects with and without chronic kidney disease (CKD). Confirmation is required for its safety, treatment adherence, renal function effect, and mortality in patients with CKD. A retrospective cohort study was conducted to compare new users of denosumab in terms of their two-year drug adherence in all participants (overall cohort) and CKD participants (CKD subcohort), which was defined as baseline estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m². The eGFR was calculated using the 2021 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. We defined high adherence (HA) users as receiving three or four doses and low adherence (LA) users as receiving one or two doses. All-cause mortality was analyzed using Kaplan–Meier curves and Cox regression models. In total, there were 1142 subjects in the overall cohort and 500 subjects in the CKD subcohort. HA users had better renal function status at baseline than LD users in the overall cohort. A decline in renal function was only observed among LD users in the overall cohort. In the CKD subcohort, no baseline renal function difference or renal function decline was demonstrated. The all-cause mortality rate of HA users was lower than LA users in both the overall cohort and CKD. A randomized control trial is warranted to target this unique population to confirm our observations.

Effects of osteoporosis medications on bone fracture in patients with chronic kidney disease

PURPOSE OF THE STUDY

The risk of bone fracture is high in patients with chronic kidney disease (CKD), and aggressive treatment to reduce fragility fracture risk is the major strategy. However, the outcomes of osteoporosis medications in patients with CKD remain unclear.

STUDY DESIGN

Patients with stage 3-5 CKD during 2011-2019 were enrolled. Patients were divided into two groups based on receiving osteoporosis medications (bisphosphonates, raloxifene, teriparatide or denosumab) or not. Two groups were matched at a 1:1 ratio by using propensity scores. The outcomes of interest were bone fractures, cardiovascular (CV) events and all-cause mortality. Cox proportional hazard regression models were applied to identify the risk factors. Additional stratified analyses by cumulative dose, treatment length and menopause condition were performed.

RESULTS AND CONCLUSIONS

67 650 patients were included. After propensity score matching, 1654 patients were included in the study and control group, respectively. The mean age was 70.2±12.4 years, and 32.0% of patients were men. After a mean follow-up of 3.9 years, the incidence rates of bone fracture, CV events and all-cause mortality were 2.0, 1.7 and 6.5 per 1000 person-months, respectively. Multivariate analysis results showed that osteoporosis medications reduced the risk of CV events (HR, 0.35; 95% CI, 0.18 to 0.71; p=0.004), but did not alleviate the risks of bone fracture (HR, 1.48; 95% CI, 0.73 to 2.98; p=0.28) and all-cause mortality (HR, 0.93; 95% CI, 0.67 to 1.28; p=0.65). Stratified analysis showed that bisphosphonates users have most benefits in the reduction of CV events (HR, 0.26; 95% CI, 0.11 to 0.64; p=0.003). In conclusion, osteoporosis medications did not reduce the risk of bone fractures, or mortality, but improved CV outcomes in patients with CKD.

Usefulness of cortical thickness ratio of the third metacarpal bone for prediction of major osteoporotic fractures

Objective

Patients with rheumatoid arthritis (RA) are at high risk for osteoporotic fractures. We developed an index called the third metacarpal cortical thickness ratio (CTR), which reflects bone mineral density (BMD) in RA patients. A longitudinal study was conducted to verify the usefulness of CTR during the follow-up period.

Methods

Patients with RA who underwent dual energy X-ray absorptiometry (DXA) and hand X-ray simultaneously were monitored for disease activity and activities of daily living at 3-month intervals, and BMD and CTR were measured at 1-year intervals. Mean CTR during follow-up was tested for correlation with mean BMD at both the lumbar spine (LS) and femoral neck (FN) during follow-up. Correlations were examined, including other variants potentially correlated with BMD. The risk ratio of accidental major osteoporotic fractures (MOF) in the variance including CTR and BMD was evaluated.

Results

A total of 300 patients, 40 men and 260 women, were enrolled. Mean follow-up length was 49.6 months. CTR was significantly associated with BMD in FN using a multivariate model of linear regression analysis (p < 0.0001), whereas CTR was significantly associated with BMD in LS using only a univariate model (p < 0.01). The only variant with a significantly higher risk ratio for incident MOF was the presence of prevalent MOF. CTR and BMD did not show a significantly higher risk ratio using Cox regression analysis.

Conclusion

CTR correlated significantly with BMD even during follow-up, especially in FN. However, CTR and BMD were not risk factors for major MOF.

•

Correlation between cortical thickness ratio of the third metacarpal bone and incident osteoporotic fracture was evaluated.

•

Correlations were confirmed using longitudinal as well as cross-sectional studies.

•

The CTR did not show a significant higher risk ratio for the development of osteoporotic fractures, though BMD also did not

•

Possibility in which the RA patient causes the incidental fracture by the reason except for the bone density is indicated.

Polypharmacy, chronic kidney disease, and incident fragility fracture: a prospective cohort study

INTRODUCTION

Polypharmacy is associated with an increased risk of fracture in aging populations, but no study has accounted for the impact of kidney function on this association. This study aimed to examine the association between polypharmacy and incident fragility fracture based on chronic kidney disease (CKD) status.

MATERIALS AND METHODS

Participants were 2023 patients (55% men; mean age, 69 years) of Sado General Hospital enrolled in the Project in Sado for Total Health (PROST) between June 2008 and December 2016. Among these, 65%, 28%, and 7% had non-CKD, non-dialysis-dependent CKD, and dialysis-dependent CKD, respectively. Multivariable Cox proportional hazards analysis was conducted with adjustments for potential confounders.

RESULTS

Prevalences of polypharmacy (≥ 5 medications) and hyperpolypharmacy (≥ 10 medications) among participants were 43% and 9% for non-CKD, 62% and 23% for non-dialysis-dependent CKD, and 85% and 34% for dialysis-dependent CKD, respectively. During a median follow-up of 5.6 years, 256 fractures occurred. More medications were associated with a higher risk of fractures. Specifically, compared to participants without polypharmacy, adjusted hazard ratios were 1.32 (95% CI 0.96-1.79) and 1.99 (1.35-2.92) for those with polypharmacy and hyperpolypharmacy, respectively, after adjusting for osteoporosis risk factors, CKD status, and comorbidities. No effect modification by CKD status was observed (interaction P = 0.51). Population-attributable fractions of hyperpolypharmacy for fracture were 9.9% in the total cohort and 42.1% in dialysis-dependent CKD patients.

CONCLUSION

Hyperpolypharmacy is associated with an increased risk of fragility fracture regardless of CKD status, and has a strong impact on incident fragility fractures in dialysis-dependent CKD patients.

Perioperative Management and Outcomes of Hip Fracture Patients with Advanced Chronic Kidney Disease

Aims

To explore clinical characteristics, perioperative management and outcomes of Hip Fracture patients with advanced Chronic Kidney Disease (HF-aCKD) compared to the general Hip Fracture population without aCKD (HF-G) within a large volume tertiary hospital in Western Australia.

Methods

Retrospective chart review of patients admitted with hip fracture (HF) to a single large volume tertiary hospital registered on Australian and New Zealand Hip Fracture Registry (ANZHFR). We compared baseline demographic and clinical frailty scale (CFS) of HF-aCKD (n = 74), defined as eGFR < 30 mls/min/1.73 m2, with HF-G (n = 452) and determined their outcomes at 120 days.

Results

We identified 74 (6.97%) HF patients with aCKD. General demographics were similar in HF-aCKD and HF-G populations. 120-days mortality for HF-aCKD was double that of HF-G population (34% vs 17%, P = .001). For dialysis patients, 120-days mortality was triple that of HF-G population (57%). Except for the fit category of HF-aCKD group, higher CFS was associated with higher 120-days mortality in both groups.  Of all HF-aCKD patients, 96% had operative intervention and 48% received blood transfusion. There were no new starts to dialysis peri-operatively. Each point reduction in eGFR below 12 mL/min/1.73 m2 was associated with 3% increased probability of death in hospital.

Conclusions

120-days mortality was double in HF-aCKD and triple in HF-dialysis that of the HF-G within our institution. Clinical frailty scale can be useful in predicting mortality after HF in frail aCKD patients. High rate of blood transfusions was observed in HF-aCKD group. Further studies with larger HF-aCKD numbers are required to explore these associations in detail.

The Impact of High Dose Glucocorticoids on Bone Health and Fracture Risk in Systemic Vasculitides

Systemic vasculitides are a range of conditions characterized by inflammation of blood vessels which may manifest as single organ or life-threatening multisystem disease. The treatment of systemic vasculitis varies depending on the specific disease but historically has involved initial treatment with high dose glucocorticoids alone or in conjunction with other immunosuppressive agents. Prolonged glucocorticoid treatment is frequently required as maintenance treatment. Patients with small and large vessel vasculitis are at increased risk of fracture. Osteoporosis may occur due to intrinsic factors such as chronic inflammation, impaired renal function and to a large extent due to pharmacological therapy with high dose glucocorticoid or combination treatments. This review will outline the known mechanism of bone loss in vasculitis and will summarize factors attributing to fracture risk in different types of vasculitis. Osteoporosis treatment with specific consideration for patients with vasculitis will be discussed. The use of glucocorticoid sparing immunosuppressive agents in the treatment of systemic vasculitis is a significant area of ongoing research. Adjunctive treatments are used to reduce cumulative doses of glucocorticoids and therefore may significantly decrease the associated fracture risk in patients with vasculitis. Lastly, we will highlight the many unknowns in the relation between systemic vasculitis, its treatment and bone health and will outline key research priorities for this field.

Recent Advances in the Role of Diet in Bone and Mineral Disorders in Chronic Kidney Disease

PURPOSE OF REVIEW

Chronic kidney disease mineral and bone disease (CKD-MBD) is a common complication of kidney disease and is strongly influenced by diet. The purpose of this manuscript is to review recent advances in the role of diet in CKD-MBD over the last 5 years.

RECENT FINDINGS

Many of the recent studies examining the role of diet in CKD-MBD have focused on the adverse effects of high phosphorus consumption on bone health and metabolism. In general, the studies have shown that high phosphorus consumption worsens markers of bone and mineral metabolism but that eating a diet with a calcium to phosphorus ratio closer to 1:1 can attenuate some of these effects. Recent studies also showed that dietary counseling is efficacious for improving markers of CKD-MBD. High consumption of phosphorus aggravates CKD-MBD. Dietary counseling may ameliorate these effects, for example, by consuming diets with higher calcium to phosphorus ratios.

Toxic Effects of Indoxyl Sulfate on Osteoclastogenesis and Osteoblastogenesis

Uremic toxins, such as indoxyl sulfate (IS) and kynurenine, accumulate in the blood in the event of kidney failure and contribute to further bone damage. To maintain the homeostasis of the skeletal system, bone remodeling is a persistent process of bone formation and bone resorption that depends on a dynamic balance of osteoblasts and osteoclasts. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates the toxic effects of uremic toxins. IS is an endogenous AhR ligand and is metabolized from tryptophan. In osteoclastogenesis, IS affects the expression of the osteoclast precursor nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) through AhR signaling. It is possible to increase osteoclast differentiation with short-term and low-dose IS exposure and to decrease differentiation with long-term and/or high-dose IS exposure. Coincidentally, during osteoblastogenesis, through the AhR signaling pathway, IS inhibits the phosphorylation of ERK, and p38 reduces the expression of the transcription factor 2 (Runx2), disturbing osteoblastogenesis. The AhR antagonist resveratrol has a protective effect on the IS/AhR pathway. Therefore, it is necessary to understand the multifaceted role of AhR in CKD, as knowledge of these transcription signals could provide a safe and effective method to prevent and treat CKD mineral bone disease.

Musculoskeletal ambulation disability symptom complex as a risk factor of incident bone fragility fracture

Objectives

Influence of presenting musculoskeletal ambulation disability symptom complex (MADS) on occurrence of bone fragility fracture (BFF) is investigated with retrospective cohort study.

Methods

A total of 931 subjects joined in the study. Subjects were selected as bone fragility risk positive in the fracture assessment tool questionnaire. Their assumed risk factors were harvested from the medical records and X-ray pictures. They were followed up at least 8 years consecutively, and occurrence of incident BFF was set as primary endpoint. Each assumed risk factor including MADS was evaluated using Cox regression analysis. Subjects were divided into 2 groups according to presence of MADS (G-MADS and G-noMADS). Adjusted hazard ratios between the 2 groups was evaluated using Cox regression analysis. The statistical procedures were performed before and after propensity score matching (PSM) procedures in order to make parallel with assumed risk factors.

Results

Statistically significant risk factors within 5% were prevalent vertebral body fracture, disuse, MADS, cognitive disorder, hypertension, contracture, Parkinsonism, being female sex, hyperlipidemia, insomnia, T-score in the femoral neck ≤ −2.3, chronic kidney disease ≥ stage 2, chronic obstructive pulmonary diseases, glucocorticoid steroid administrated, and osteoarthritis in order of the adjusted hazard ratios (from highest to lowest). Adjusted hazard ratios between G-MADS and G-noMADS were 2.70 and 1.83 for before and after PSM, respectively.

Conclusions

MADS demonstrated as a significant risk factor of BFF occurrence. In treating osteoporosis, fall risk should be aware of as well as bone fragility risk.

Effect of chronic kidney disease on outcomes following proximal humerus fragility fracture surgery in diabetic patients: A nationwide population-based cohort study

BACKGROUND

The proximal humerus fracture (PHF) is the third most common fragility fracture. Diabetes mellitus (DM) and chronic kidney disease (CKD) are both risks for fragility fractures; however, the interplay of DM and CKD makes treatment outcomes unpredictable. This study aimed to investigate and compare early and late outcomes following proximal humerus fracture fixation surgery in diabetic patients with different renal function conditions.

METHODS

DM patients receiving PHF fixation surgery during 1998-2013 were recruited from Taiwan's National Health Insurance Research Database. According to their renal function, patients were divided into three study groups: non-chronic kidney disease (CKD), non-dialysis CKD, and dialysis. Outcomes of interest were early and late perioperative outcomes. Early outcomes included in-hospital newly-onset morbidities. Late outcomes included infection, revision, readmission, and all-cause mortality.

RESULTS

This study included a total of 10,850 diabetic patients: 2152 had CKD (non-dialysis CKD group), 196 underwent permanent dialysis (dialysis group), and the remaining 8502 did not have CKD (non-CKD group). During a mean follow-up of 5.56 years, the dialysis group showed the highest risk of overall infection, all-cause revision, readmission, and mortality compared to the non-dialysis CKD group and non-CKD group. Furthermore, subgroup analysis showed that CKD patients had a higher risk of surgical infection following PHF surgery than non-CKD patients in cases with a traffic accident or fewer comorbidities (Charlson Comorbidity Index, CCI <3) (P for interaction: 0.086 and 0.096, respectively). Also, CKD patients had an even higher mortality risk after PHF surgery than non-CKD patients, in females, those living in higher urbanization areas, or with more comorbidities (CCI ≥3) (P for interaction: 0.011, 0.057, and 0.069, respectively).

CONCLUSION

CKD was associated with elevated risks for infection, revision, readmission, and mortality after PHF fixation surgery in diabetic patients. These findings should be taken into consideration when caring for diabetic patients.

The Role of DMP1 in CKD-MBD

PURPOSE OF REVIEW

Chronic kidney disease-mineral and bone disorder (CKD-MBD) has become a global health crisis with very limited therapeutic options. Dentin matrix protein 1 (DMP1) is a matrix extracellular protein secreted by osteocytes that has generated recent interest for its possible involvement in CKD-MBD pathogenesis. This is a review of DMP1 established regulation and function, and early studies implicating DMP1 in CKD-MBD.

RECENT FINDINGS

Patients and mice with CKD show perturbations of DMP1 expression in bone, associated with impaired osteocyte maturation, mineralization, and increased fibroblast growth factor 23 (FGF23) production. In humans with CKD, low circulating DMP1 levels are independently associated with increased cardiovascular events. We recently showed that DMP1 supplementation lowers circulating FGF23 levels and improves bone mineralization and cardiac outcomes in mice with CKD. Mortality rates are extremely high among patients with CKD and have only marginally improved over decades. Bone disease and FGF23 excess contribute to mortality in CKD by increasing the risk of bone fractures and cardiovascular disease, respectively. Previous studies focused on DMP1 loss-of-function mutations have established its role in the regulation of FGF23 and bone mineralization. Recent studies show that DMP1 supplementation may fill a crucial therapeutic gap by improving bone and cardiac health in CKD.

T Scores, FRAX, Frailty Phenotype, Falls, and Its Relationship to Fractures in Patients on Maintenance Hemodialysis

Background:

Despite the magnitude of fracture and the consequences in patients receiving hemodialysis, optimal risk assessment tools in this population are not well explored. Frailty and falls—known risk factors for fracture in chronic kidney disease (CKD) and non-CKD populations—are common in patients receiving hemodialysis (HD) therapy. While the relationship between T scores in relation to fractures in patients receiving HD is recognized, there is a paucity of data to the additional contributions of fracture assessment tool (FRAX), frailty status, and falls in its relationship with fracture.

Objectives:

To evaluate the clinical utility of adding FRAX, frailty status, and falls to T scores at the femoral neck to determine whether it enhances fracture discrimination in patients on maintenance HD.

Design:

A cross-sectional observational study.

Setting:

Two main dialysis units in Regina, Saskatchewan, Canada.

Patients:

A total of 109 patients on maintenance HD at two dialysis units from January 1, 2017, to December 31, 2018, were included in the study.

Measurements:

Fracture (the main outcome) was documented based on the review of medical charts, self-recall, and additionally vertebral fractures were identified by an x-ray. Areal bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry (DXA). FRAX score was calculated using an online algorithm based on 11 clinical risk factors. We calculated the FRAX score for hip fracture and major osteoprotoic fracture with and without the inclusion of BMD. Frailty was assessed using the Fried criteria, which included assessments of unintentional weight loss, weakness (handgrip strength), slowness (walking speed), and questionnaires for physical activity and self-perceived exhaustion. Patients were enquired about the history and frequency of falls.

Methods:

A total of 131 patients underwent frailty assessments at the two dialysis units during the dialysis treatment. Following frailty assessments, they were referred for DXA scans and upon receipt of the results undertook FRAX questionnaires. They were additionally sent for lumbar x-rays and contacted for a history of falls. Association between the BMD-T score, FRAX, frailty status, falls, with fracture were examined with sequential multivariable logistic regression models. Differences were considered statistically significant at P values <.05.

Results:

A total of 109 patients were included in the data analysis. The composite of fracture occurred in 37.6% of patients. About 59.3% were identified as frail, and 29% of the participants had at least one fall in the last year. On multivariate regression analysis, each lower standard deviation (SD) in femoral neck T score was associated with 48% higher odds of fracture (odds ratio [OR] = 1.48; 95% confidence interval [CI] 1.20-1.68, P = .005). With the inclusion for FRAX scores (hip), the OR for fracture remained significant at 1.38 (OR = 1.38, 95% CI 1.04-1.63, P = .043). The addition of frailty status and history of falls did not further improve the model. Low T score and FRAX were both independent risk factors in patients on HD therapy.

Limitations:

This is a single-center study with a small sample size which limits the generalizability of the findings. Due to the cross-sectional study, associations identified may be difficult to interpret.

Conclusions:

Both BMD measurements by DXA and FRAX are useful tools to assess fracture in patients receiving HD. The addition of frailty status and history of falls is not associated with fractures in this population. Larger prospective studies are needed to determine whether the inclusion of frailty and falls to the conventional models will improve fracture assessment in the population receiving HD.

Trial Registration:

The study was not registered on a publicly accessible registry as it did not involve health care intervention on human participants.

Pharmacological interventions versus placebo, no treatment or usual care for osteoporosis in people with chronic kidney disease stages 3-5D

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for osteoporosis and is more prevalent among people with CKD than among people who do not have CKD. Although several drugs have been used to effectively treat osteoporosis in the general population, it is unclear whether they are also effective and safe for people with CKD, who have altered systemic mineral and bone metabolism.

OBJECTIVES

To assess the efficacy and safety of pharmacological interventions for osteoporosis in patients with CKD stages 3-5, and those undergoing dialysis (5D).

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 25 January 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials comparing any anti-osteoporotic drugs with a placebo, no treatment or usual care in patients with osteoporosis and CKD stages 3 to 5D were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their quality using the risk of bias tool, and extracted data. The main outcomes were the incidence of fracture at any sites; mean change in the bone mineral density (BMD; measured using dual-energy radiographic absorptiometry (DXA)) of the femoral neck, total hip, lumbar spine, and distal radius; death from all causes; incidence of adverse events; and quality of life (QoL). Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Seven studies involving 9164 randomised participants with osteoporosis and CKD stages 3 to 5D met the inclusion criteria; all participants were postmenopausal women. Five studies included patients with CKD stages 3-4, and two studies included patients with CKD stages 5 or 5D. Five pharmacological interventions were identified (abaloparatide, alendronate, denosumab, raloxifene, and teriparatide). All studies were judged to be at an overall high risk of bias. Among patients with CKD stages 3-4, anti-osteoporotic drugs may reduce the risk of vertebral fracture (RR 0.52, 95% CI 0.39 to 0.69; low certainty evidence). Anti-osteoporotic drugs probably makes little or no difference to the risk of clinical fracture (RR 0.91, 95% CI 0.79 to 1.05; moderate certainty evidence) and adverse events (RR 0.99, 95% CI 0.98 to 1.00; moderate certainty evidence). We were unable to incorporate studies into the meta-analyses for BMD at the femoral neck, lumbar spine and total hip as they only reported the percentage change in the BMD in the intervention group. Among patients with severe CKD stages 5 or 5D, it is uncertain whether anti-osteoporotic drug reduces the risk of clinical fracture (RR 0.33, 95% CI 0.01 to 7.87; very low certainty evidence). It is uncertain whether anti-osteoporotic drug improves the BMD at the femoral neck because the certainty of this evidence is very low (MD 0.01, 95% CI 0.00 to 0.02). Anti-osteoporotic drug may slightly improve the BMD at the lumbar spine (MD 0.03, 95% CI 0.03 to 0.04, low certainty evidence). No adverse events were reported in the included studies. It is uncertain whether anti-osteoporotic drug reduces the risk of death (RR 1.00, 95% CI 0.22 to 4.56; very low certainty evidence).

AUTHORS' CONCLUSIONS

Among patients with CKD stages 3-4, anti-osteoporotic drugs may reduce the risk of vertebral fracture in low certainty evidence. Anti-osteoporotic drugs make little or no difference to the risk of clinical fracture and adverse events in moderate certainty evidence. Among patients with CKD stages 5 and 5D, it is uncertain whether anti-osteoporotic drug reduces the risk of clinical fracture and death because the certainty of this evidence is very low. Anti-osteoporotic drug may slightly improve the BMD at the lumbar spine in low certainty evidence. It is uncertain whether anti-osteoporotic drug improves the BMD at the femoral neck because the certainty of this evidence is very low. Larger studies including men, paediatric patients or individuals with unstable CKD-mineral and bone disorder are required to assess the effect of each anti-osteoporotic drug at each stage of CKD.

Adenine-induced chronic kidney disease induces a similar skeletal phenotype in male and female C57BL/6 mice with more severe deficits in cortical bone properties of male mice

Chronic kidney disease (CKD) causes bone loss, particularly in cortical bone, through formation of cortical pores which lead to skeletal fragility. Animal models of CKD have shown variability in the skeletal response to CKD between males and females suggesting sex may play a role in this variation. Our aim was to compare the impact of adenine-induced CKD on cortical parameters in skeletally mature male and female C57Bl/6 mice. After 10-weeks of adenine-induced CKD, both male and female adenine mice had high serum parathyroid hormone (PTH), high bone turnover, and cortical porosity compared to non-CKD controls. Both sexes had lower cortical thickness, but only male mice had lower cortical bone area. CKD imparted greater deficits in mechanical properties of male mice compared to female mice. These data demonstrate that both male and female mice develop high PTH/high bone turnover in response to adenine-induced CKD and that cortical bone phenotypes are slightly more severe in males, particularly in mechanical properties deficits.

Fluoride in Drinking Water, Diet, and Urine in Relation to Bone Mineral Density and Fracture Incidence in Postmenopausal Women

BACKGROUND

Although randomized controlled trials (RCTs) have demonstrated that high fluoride increases bone mineral density (BMD) and skeletal fragility, observational studies of low-dose chronic exposure through drinking water (<1.5mg/L, the maximum recommended by the World Health Organization) have been inconclusive.

OBJECTIVE

We assessed associations of fluoride in urine, and intake via diet and drinking water, with BMD and fracture incidence in postmenopausal women exposed to drinking water fluoride ≤1mg/L.

METHODS

Data were from participants in the Swedish Mammography Cohort-Clinical, a population-based prospective cohort study. At baseline (2004-2009), fluoride exposure was assessed based on urine concentrations (n=4,306) and estimated dietary intake (including drinking water) (n=4,072), and BMD was measured using dual energy X-ray absorptiometry. Incident fractures were ascertained via register-linkage through 2017. Residential history was collected to identify women with long-term consistent drinking water exposures prior to baseline.

RESULTS

At baseline, mean urine fluoride was 1.2mg/g creatinine (±1.9) and mean dietary intake was 2.2mg/d (±0.9), respectively. During follow-up, 850, 529, and 187 cases of any fractures, osteoporotic fractures, and hip fractures, respectively, were ascertained. Baseline BMD was slightly higher among women in the highest vs. lowest tertiles of exposure. Fluoride exposures were positively associated with incident hip fractures, with multivariable-adjusted hazard ratios of 1.50 (95% CI: 1.04, 2.17) and 1.59 (95% CI: 1.10, 2.30), for the highest vs. lowest tertiles of urine fluoride and dietary fluoride, respectively. Associations with other fractures were less pronounced for urine fluoride, and null for dietary fluoride. Restricting the analyses to women with consistent long-term drinking water exposures prior to baseline strengthened associations between fractures and urinary fluoride.

DISCUSSION

In this cohort of postmenopausal women, the risk of fractures was increased in association with two separate indicators of fluoride exposure. Our findings are consistent with RCTs and suggest that high consumption of drinking water with a fluoride concentration of ∼1mg/L may increase both BMD and skeletal fragility in older women. https://doi.org/10.1289/EHP7404.

Prognostic performance of clinical assessment tools following hip fracture in patients with chronic kidney disease

Purpose

People living with chronic kidney disease (CKD) are at a higher risk of hip fracture with an associated increased mortality risk compared to individuals without CKD. Our study aimed to evaluate the clinical assessment tools that best predict mortality risk following hip fracture for patients with CKD.

Methods

Patients with CKD G3b-5D admitted to Lancashire Teaching Hospitals NHS Foundation Trust, U.K. between June 2013 and Dec 2019 were included. The association between CKD and post-fracture mortality risk was evaluated. All patients were assessed using tools that evaluated frailty status, co-morbidity, pre-operative risk, functional status and cardiopulmonary fitness. Receiver operating characteristic curve analyses were performed to determine the prognostic accuracy of the assessment tools for 30 day and 1 year mortality following hip fracture in patients with CKD.

Results

397 patients fulfilled inclusion criteria with a mean age of 83.5 ± 9.2 years. Older age, female sex, intracapsular fracture and more severe CKD, co-morbidity and frailty status were all associated with an increased mortality risk. Patients with dialysis-dependent CKD and severe/very severe frailty had a hazard ratio for mortality of 2.55 (95% Cl 2.11–2.98) and 3.11 (95% Cl 2.47–3.93), respectively. The Clinical Frailty Scale demonstrated the best prognostic accuracy for both 30 day [Area Under the Curve (AUC) 0.91, 95% Cl 0.84–0.97] and 1 year mortality (AUC 0.93, 95% Cl 0.87–1.00).

Conclusion

Patients with advanced CKD and severe frailty have a high mortality risk following hip fracture. The Clinical Frailty Scale is an excellent prognostic tool for mortality in this setting and could be easily incorporated into routine clinical practice.

Mineral Bone Disorders in Kidney Transplantation

Bone disease after kidney transplantation is associated with an increased risk of fractures, morbidity, and mortality. Its pathophysiology is complex, involving multiple contributors including pretransplant bone disease, immunosuppressive medications, and changes in the parathyroid-bone-kidney axis. Risk scores, bone turnover markers, and noninvasive imaging modalities are only able to partially predict the fracture risk in kidney transplant recipients. The optimal management of bone disease after kidney transplantation has not yet been established, with only a limited number of randomized clinical trials evaluating the efficacy of treatment regimens in kidney transplant recipients. This review focuses on the pathophysiology, evaluation, prevention, and treatment of post-kidney transplant mineral and bone disease as guided by recent evidence.

Reversing cortical porosity: Cortical pore infilling in preclinical models of chronic kidney disease

PURPOSE

Chronic kidney disease (CKD) patients have a high incidence of fracture due in part to cortical porosity. The goal of this study was to study cortical pore infilling utilizing two rodent models of progressive CKD.

METHODS

Exp 1: Female C57Bl/6J mice (16-week-old) were given dietary adenine (0.2%) to induce CKD for 10 weeks after which calcium water supplementation (Ca-H2O; 1.5% and 3%) was given to suppress PTH for another 4 weeks. Exp 2: Male Cy/+ rats were aged to ~30 weeks with baseline porosity assessed using in vivo μCT. A second in vivo scan followed 5-weeks of Ca-H2O (3%) supplementation.

RESULTS

Exp 1: Untreated adenine mice had elevated blood urea nitrogen (BUN), parathyroid hormone (PTH), and cortical porosity (~2.6% porosity) while Ca-H2O lowered PTH and cortical porosity (0.5-0.8% porosity). Exp 2: Male Cy/+ rats at baseline had variable porosity (0.5%-10%), but after PTH suppression via Ca-H2O, cortical porosity in all rats was lower than 0.5%. Individual pore dynamics measured via a custom MATLAB code demonstrated that 85% of pores infilled while 12% contracted in size.

CONCLUSION

Ca-H2O supplementation causes net cortical pore infilling over time and imparted mechanical benefits. While calcium supplementation is not a viable clinical treatment for CKD, these data demonstrate pore infilling is possible and further research is required to examine clinically relevant therapeutics that may cause net pore infilling in CKD.