Cost effectiveness of teriparatide and PTH(1-84) in the treatment of postmenopausal osteoporosis

Albiflorin Promotes Osteoblast Differentiation and Healing of Rat Femoral Fractures Through Enhancing BMP-2/Smad and Wnt/β-Catenin Signaling

Fracture healing is related to osteogenic differentiation and mineralization. Recently, due to the unwanted side effects and clinical limitations of existing treatments, various natural product-based chemical studies have been actively conducted. Albiflorin is a major ingredient in Paeonia lactiflora, and this study investigated its ability to promote osteogenic differentiation and fracture healing. To demonstrate the effects of albiflorin on osteoblast differentiation and calcified nodules, alizarin red S staining and von Kossa staining were used in MC3T3-E1 cells. In addition, BMP-2/Smad and Wnt/β-catenin mechanisms known as osteoblast differentiation mechanisms were analyzed through RT-PCR and western blot. To investigate the effects of albiflorin on fracture healing, fractures were induced using a chainsaw in the femur of Sprague Dawley rats, and then albiflorin was intraperitoneally administered. After 1, 2, and 3 weeks, bone microstructure was analyzed using micro-CT. In addition, histological analysis was performed by staining the fractured tissue, and the expression of osteogenic markers in serum was measured. The results demonstrated that albiflorin promoted osteoblastogenesis and the expression of RUNX2 by activating BMP-2/Smad and Wnt/β-catenin signaling in MC3T3-E1 cells. In addition, albiflorin upregulated the expression of various osteogenic genes, such as alkaline phosphatase, OCN, bone sialoprotein, OPN, and OSN. In the femur fracture model, micro-CT analysis showed that albiflorin played a positive role in the formation of callus in the early stage of fracture recovery, and histological examination proved to induce the expression of osteogenic genes in femur tissue. In addition, the expression of bone-related genes in serum was also increased. This suggests that albiflorin promotes osteogenesis, bone calcification and bone formation, thereby promoting the healing of fractures in rats.

A novel economic framework to assess the cost-effectiveness of bone-forming agents in the prevention of fractures in patients with osteoporosis

A novel cost-effectiveness model framework was developed to incorporate the elevated fracture risk associated with a recent fracture and to allow sequential osteoporosis therapies to be evaluated. Treating patients with severe osteoporosis after a recent fracture with a bone-forming agent followed by antiresorptive therapy can be cost-effective compared with antiresorptive therapy alone. Incorporating these novel technical attributes in economic evaluations can support appropriate policy and reimbursement decision-making.

PURPOSE

To develop a cost-effectiveness model accommodating increased fracture risk after a recent fracture and treatment sequencing.

METHODS

A micro-simulation cost-utility model was developed to accommodate both treatment sequencing and increased risk with recent fracture. The risk of fracture was estimated and simulated using the FRAX® algorithms combined with Swedish registry data on imminent fracture relative risk. In the base-case cost-effectiveness analysis, a sequential treatment starting with a bone-forming agent for 12 months followed by an antiresorptive agent for 48 months initiated immediately after a major osteoporotic fracture (MOF) in a 70-year-old woman with a T-score of 2.5 or less was compared to an antiresorptive treatment alone for 60 months. The model was populated with data relevant for a UK population reflecting a personal social service perspective.

RESULTS

The cost per additional quality-adjusted life year (QALY) gained in the base-case setting was estimated at £34,584. Sensitivity analyses revealed the sequential treatment to be cost-saving compared with administering a bone-forming treatment alone. Without simulating an elevated fracture risk immediately after a recent fracture, the cost per QALY changed from £34,584 to £62,184.

CONCLUSION

Incorporating imminent fracture risk in economic evaluations has a significant impact on the cost-effectiveness when evaluating fracture prevention treatments in patients with osteoporosis who sustained a recent fracture. Bone-forming treatment followed by antiresorptive therapy can be cost-effective compared to antiresorptive therapy alone depending on treatment acquisition costs.

Cost-effectiveness of romosozumab for the treatment of postmenopausal women with severe osteoporosis at high risk of fracture in Sweden

Romosozumab is a novel bone-building drug that reduces fracture risk. This health economic analysis indicates that sequential romosozumab-to-alendronate can be a cost-effective treatment option for postmenopausal women with severe osteoporosis at high risk of fracture.

PURPOSE

To estimate the cost-effectiveness of sequential treatment with romosozumab followed by alendronate ("romosozumab-to-alendronate") compared with alendronate alone in patients with severe osteoporosis at high risk of fracture in Sweden.

METHODS

A microsimulation model with a Markov structure was used to simulate fractures, costs, and quality-adjusted life years (QALYs), for women treated with romosozumab-to-alendronate or alendronate alone. Patients aged 74 years with a recent major osteoporotic fracture (MOF) were followed from the start of treatment until the age of 100 years or death. Treatment with romosozumab for 12 months was followed by alendronate for up to 48 months or alendronate alone with a maximum treatment duration of 60 months. The analysis had a societal perspective. Efficacy of romosozumab and alendronate were derived from phase III randomized controlled trials. Resource use and unit costs were collected from the literature. Cost-effectiveness was estimated using incremental cost-effectiveness ratio (ICER) with QALYs as effectiveness measures.

RESULTS

The base case analysis showed that sequential romosozumab-to-alendronate treatment was associated with 0.089 additional QALYs at an additional cost of €3002 compared to alendronate alone, resulting in an ICER of €33,732. At a Swedish reference willingness-to-pay per QALY of €60,000, romosozumab-to-alendronate had a 97.9% probability of being cost-effective against alendronate alone. The results were most sensitive to time horizon, persistence assumptions, patient age, and treatment efficacy.

CONCLUSION

The results of this study indicate that sequential romosozumab-to-alendronate can be a cost-effective treatment option for postmenopausal women with severe osteoporosis at high risk of fracture.

Systematic evidence of health economic evaluation of drugs for postmenopausal osteoporosis: A quality appraisal

This paper systematically and critically reviewed all published economic evaluations of drugs for the treatment of postmenopausal osteoporosis. A systematic search was conducted using relevant databases for economic evaluations to include all relevant English articles published between January 2008 to January 2020. After extracting the key study characteristics, methods and outcomes, we evaluated each article using the Quality of Health Economic Studies (QHES) and the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) instruments. A total of 49 studies met the inclusion criteria. Majority of studies were funded by the industry and reported favorable cost-effectiveness. Based on the QHES total scores, studies (n = 35) were found to be industry-funded with higher QHES mean 82.44 ± 8.69 as compared with nonindustry funding studies (n = 11) with mean 72.22 ± 17.67. The overall mean QHES scores were found to be higher 79.06 ± 11.84, representing high quality (75–100) compared to CHEERS scores (%) 75.03 ± 11.21. The statistical pairwise comparison between CHEERS mean (75.03 ± 11.21) and QHES mean (79.06 ± 11.84) were not statistically significant (P = 0.10) whereas, QHES score showed higher means as compared to CHEERS. This study suggests the overall quality of the published literatures was relatively few high-quality health economic evaluation demonstrating the cost-effectiveness of drugs for postmenopausal osteoporosis, and the majority of the literature highlights that methodological shortcoming.

Cost-effectiveness Analysis of Sequential Treatment of Abaloparatide Followed by Alendronate Versus Teriparatide Followed by Alendronate in Postmenopausal Women With Osteoporosis in the United States

BACKGROUND

The US Food and Drug Administration has recently approved abaloparatide (ABL) for treatment of women with postmenopausal osteoporosis (PMO) at high risk of fracture. With increasing health care spending and drug prices, it is important to quantify the value of newly available treatment options for PMO.

OBJECTIVE

To determine cost-effectiveness of ABL compared with teriparatide (TPTD) for treatment of women with PMO in the United States.

METHODS

A discrete-event simulation (DES) model was developed to assess cost-effectiveness of ABL from the US health care perspective. The model included three 18-month treatment strategies with either placebo (PBO), TPTD, or ABL, all followed by additional 5-year treatment with alendronate (ALN). High-risk patients were defined as women with PMO ⩾65 years old with a prior vertebral fracture. Baseline clinical event rates, risk reductions, and patient characteristics were based on the Abaloparatide Comparator Trial in Vertebral Endpoints (ACTIVE) trial.

RESULTS

Over a 10-year period, the DES model yielded average total discounted per-patient costs of $10 212, $46 783, and $26 837 and quality-adjusted life-years (QALYs) of 6.742, 6.781, and 6.792 for PBO/ALN, TPTD/ALN, and ABL/ALN, respectively. Compared with TPTD/ALN, ABL/ALN accrued higher QALYs at lower cost and produced an incremental cost-effectiveness ratio (ICER) of $333 266/QALY relative to PBO/ALN. In high-risk women, ABL/ALN also had more QALYs and less cost over TPTD/ALN and yielded an ICER of $188 891/QALY relative to PBO/ALN. Conclusion and Relevance: ABL is a dominant treatment strategy over TPTD. In women with PMO at high risk of fracture, ABL is an alternative cost-effective treatment.

Cost-effectiveness of teriparatide compared with alendronate and risedronate for the treatment of postmenopausal osteoporosis patients in Iran

Background: Hip, vertebral and wrist fractures are the most common consequences of osteoporosis. This study aimed at analyzing the cost-effectiveness of teriparatide (CinnoPar®), compared with alendronate and risedronate, in the treatment of women aged 60 and over with postmenopausal osteoporosis in Iran. Methods: A decision tree model with a 2-year time horizon was used to compare treatment with teriparatide (CinnoPar®) with the following treatment strategies: two years of treatment with alendronate and two years of treatment with risedronate in women aged 60 years and over or those at risk of osteoporosis. Cost per QALY was calculated for 3 treatment strategies from the model. After base case analysis, one-way sensitivity analysis was performed on key parameters of the model to assess their impact on the study results and the cost-effectiveness of different treatment strategies and the model robustness. TreeAge Pro 2006 software was used for modeling and data analysis. Results: Incremental cost-effectiveness ratio (ICER) of alendronate and teriparatide than risedronate (base treatment) were US$- 2178.03 and US$483,783.67 per QALY, respectively. Therefore, the dominant and cost-effective treatment option was alendronate. In the one-way sensitivity analysis, the impact of annual 25% increase or decrease in the teriparatide cost on its ICER was remarkable. Also, reducing the discount rate from 0.03 to 0.0 had the greatest impact on the ICER of the teriparatide. Conclusion: The treatment strategy of teriparatide is more expensive than risedronate and alendronate and is associated with very little increase in QALYs. A significant reduction in teriparatide price and a limit in its use only for high-risk women and for acute and short-term treatment courses can contribute to its cost-effectiveness.

Effects of teriparatide versus alendronate for treatment of postmenopausal osteoporosis: A meta-analysis of randomized controlled trials

OBJECTIVES

Osteoporosis remains a clinical challenge. Teriparatide is an anabolic drug and alendronate is an antiresorptive agent; both are used in the treatment of osteoporosis. Comprehensive reviews investigating the comparative safety and efficacy of teriparatide versus alendronate are scarce. Therefore, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the safety and efficacy of teriparatide versus alendronate for the treatment of postmenopausal osteoporosis.

METHODS

We conducted a comprehensive literature review of the PubMed, EMBASE, Cochrane Controlled Trials Registry, and the China Academic Journal Network Publishing databases for relevant RCTs of teriparatide versus alendronate in postmenopausal osteoporosis patients. Outcome measures were percentage change in lumbar spine and femoral neck bone mineral density (BMD) and incidence of vertebral and nonvertebral fractures. Effect size was reported as weighted mean differences (WMDs) for continuous outcomes and odds ratios (OR) for dichotomous outcomes, with associated 95% confidence intervals (CIs).

RESULTS

Six trials involving 618 patients were included. The meta-analysis demonstrated a significant increase in lumbar spine BMD (WMD: 3.46, 95% CI: 2.15-4.77, P < .00001), but not femoral neck BMD (WMD = 1.50, 95% CI: 0.04-2.95, P = .04), in postmenopausal osteoporosis patients treated with teriparatide compared with alendronate for 6 to 18 months. These beneficial effects were apparent in the lumbar spine at 12 months of treatment (WMD: 4.49, 95% CI: 2.57-6.40, P < .01). Teriparatide was not superior to alendronate in reducing fracture risk (OR: -0.03, 95% CI: -0.12 to 0.07; P = .52).

CONCLUSION

Teriparatide may be superior to alendronate for increasing lumbar spine BMD in postmenopausal osteoporosis. The efficacy and safety of long-term teriparatide and alendronate treatment in postmenopausal osteoporosis should be further investigated in clinical trials.

Perception of severe osteoporosis amongst medical doctors in South Korea: Awareness, impact, and treatment

OBJECTIVES

Little is currently known about the issues surrounding management and treatment of severe osteoporosis in South Korea. Our objective was to assess doctors' views on the perception, diagnosis, and treatment of severe osteoporosis.

METHODS

Face-to-face interviews were conducted (16 February-13 March 2015) with 100 doctors (specialists in orthopedic surgery, endocrinology, neurosurgery, family medicine, or rheumatology) who treated ≥5 severe osteoporosis (T-score ≤ -2.5, plus fracture) patients per month. Respondent demographic characteristics, their perception of severe osteoporosis, its impact and treatment, and their views on current practice and unmet needs were assessed.

RESULTS

Of 416 doctors approached, 100 completed the survey (24% response rate). Most doctors (90%) specialized in orthopedic surgery, endocrinology, or neurosurgery. When diagnosing severe osteoporosis, most doctors (79%) considered both bone mineral density and fracture. Almost all doctors (≥91%) ranked disease impact and seriousness highly, but much fewer (≤25%) doctors thought society agreed. Most doctors (89%) had concerns with current treatments, switching treatments because of the efficacy and safety of bisphosphonates (>89%), the efficacy of selective estrogen receptor modulators (>71%), and the high cost of parathyroid hormone (>73%). Parathyroid hormone was ranked highest for efficacy and was preferentially prescribed to severe osteoporosis patients (mean 32.2% of prescriptions) compared with osteoporosis patients overall (3.7%). "Limitations with reimbursement" was the most commonly cited (76%) unmet need.

CONCLUSIONS

There are concerns with the safety, efficacy, and affordability of current treatments for severe osteoporosis in South Korea, as well as a perceived lack of disease awareness amongst patients and doctors.

Dedicated Perioperative Hip Fracture Comanagement Programs are Cost-effective in High-volume Centers: An Economic Analysis

BACKGROUND

Osteoporotic hip fractures are common injuries typically occurring in patients who are older and medically frail. Studies have suggested that creation of a multidisciplinary team including orthopaedic surgeons, internal medicine physicians, social workers, and specialized physical therapists, to comanage these patients can decrease complication rates, improve time to surgery, and reduce hospital length of stay; however, they have yet to achieve widespread implementation, partly owing to concerns regarding resource requirements necessary for a comanagement program.

QUESTIONS/PURPOSES

We performed an economic analysis to determine whether implementation of a comanagement model of care for geriatric patients with osteoporotic hip fractures would be a cost-effective intervention at hospitals with moderate volume. We also calculated what annual volume of cases would be needed for a comanagement program to "break even", and finally we evaluated whether universal or risk-stratified comanagement was more cost effective.

METHODS

Decision analysis techniques were used to model the effect of implementing a systems-based strategy to improve inpatient perioperative care. Costs were obtained from best-available literature and included salary to support personnel and resources to expedite time to the operating room. The major economic benefit was decreased initial hospital length of stay, which was determined via literature review and meta-analysis, and a health benefit was improvement in perioperative mortality owing to expedited preoperative evaluation based on previously conducted meta-analyses. A break-even analysis was conducted to determine the annual case volume necessary for comanagement to be either (1) cost effective (improve health-related quality of life enough to be worth additional expenses) or (2) result in cost savings (actually result in decreased total expenses). This calculation assumed the scenario in which a hospital could hire only one hospitalist (and therapist and social worker) on a full-time basis. Additionally, we evaluated the scenario where the necessary staff was already employed at the hospital and could be dedicated to a comanagement service on a part-time basis, and explored the effect of triaging only patients considered high risk to a comanagement service versus comanaging all geriatric patients. Finally, probabilistic sensitivity analysis was conducted on all critical variables, with broad ranges used for values around which there was higher uncertainty.

RESULTS

For the base case, universal comanagement was more cost effective than traditional care and risk-stratified comanagement (incremental cost effectiveness ratios of USD 41,100 per quality-adjusted life-year and USD 81,900 per quality-adjusted life-year, respectively). Comanagement was more cost effective than traditional management as long as the case volume was more than 54 patients annually (range, 41-68 patients based on sensitivity analysis) and resulted in cost savings when there were more than 318 patients annually (range, 238-397 patients). In a scenario where staff could be partially dedicated to a comanagement service, universal comanagement was more cost effective than risk-stratified comanagement (incremental cost effectiveness of USD 2300 per quality-adjusted life-year), and both comanagement programs had lower costs and better outcomes compared with traditional management. Sensitivity analysis was conducted and showed that the level of uncertainty in key variables was not high enough to change the core conclusions of the model.

CONCLUSIONS

Implementation of a systems-based comanagement strategy using a dedicated team to improve perioperative medical care and expedite preoperative evaluation is cost effective in hospitals with moderate volume and can result in cost savings at higher-volume centers. The optimum patient population for a comanagement strategy is still being defined.

LEVEL OF EVIDENCE

Level 1, Economic and Decision Analysis.

A systematic review of cost-effectiveness analyses of drugs for postmenopausal osteoporosis

BACKGROUND

Given the limited availability of healthcare resources and the recent introduction of new anti-osteoporosis drugs, the interest in the cost effectiveness of drugs in postmenopausal osteoporosis remains and even increases.

OBJECTIVE

This study aims to identify all recent economic evaluations on drugs for postmenopausal osteoporosis, to critically appraise the reporting quality, and to summarize the results.

METHODS

A literature search using Medline, the National Health Service Economic Evaluation database and the Cost-Effectiveness Analysis Registry was undertaken to identify original articles published between January 1, 2008 and December 31, 2013. Studies that assessed cost effectiveness of drugs in postmenopausal osteoporosis were included. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) statement was used to assess the quality of reporting of these articles.

RESULTS

Of 1,794 articles identified, 39 studies fulfilled the inclusion criteria. They were conducted in 14 different countries and nine active interventions were assessed. When compared with no treatment, active osteoporotic drugs were generally cost effective in postmenopausal women aged over 60-65 years with low bone mass, especially those with prior vertebral fractures. Key drivers of cost effectiveness included individual fracture risk, medication adherence, selected comparators and country-specific analyses. Quality of reporting varied between studies with an average score of 17.9 out of 24 (range 7-21.5).

CONCLUSION

This review found a substantial number of published cost-effectiveness analyses of drugs in osteoporosis in the last 6 years. Results and critical appraisal of these articles can help decision makers when prioritizing health interventions and can inform the development of future economic evaluations.

Cost-effectiveness analysis of fixation options for intertrochanteric hip fractures

BACKGROUND

Intertrochanteric hip fractures are a major source of morbidity and financial burden, accounting for 7% of osteoporotic fractures and costing nearly $6 billion annually in the United States. Traditionally, "stable" fracture patterns have been treated with an extramedullary sliding hip screw whereas "unstable" patterns have been treated with the more expensive intramedullary nail. The purpose of this study was to identify parameters to guide cost-effective implant choices with use of decision-analysis techniques to model these common clinical scenarios.

METHODS

An expected-value decision-analysis model was constructed to estimate the total costs and health utility based on the choice of a sliding hip screw or an intramedullary nail for fixation of an intertrochanteric hip fracture. Values for critical parameters, such as fixation failure rate, were derived from the literature. Three scenarios were evaluated: (1) a clearly stable fracture (AO type 31-A1), (2) a clearly unstable fracture (A3), or (3) a fracture with questionable stability (A2). Sensitivity analysis was performed to test the validity of the model.

RESULTS

The fixation failure rate and implant cost were the most important factors in determining implant choice. When the incremental cost for the intramedullary nail was set at the median value ($1200), intramedullary nailing had an incremental cost-effectiveness ratio of $50,000/quality-adjusted life year when the incremental failure rate of sliding hip screws was 1.9%. When the incremental failure rate of sliding hip screws was >5.0%, intramedullary nails dominated with lower cost and better health outcomes. The sliding hip screw was always more cost-effective for A1 fractures, and the intramedullary nail always dominated for A3 fractures. As for A2 fractures, the sliding hip screw was cost-effective in 70% of the cases, although this was highly sensitive to the failure rate.

CONCLUSIONS

Sliding hip screw fixation is likely more cost-effective for stable intertrochanteric fractures (A1) or those with questionable stability (A2), whereas intramedullary nail fixation is more cost-effective for reverse obliquity fractures (A3). These conclusions are highly sensitive to the fixation failure rate, which was the major influence on the model results.

A systematic review of models used in cost-effectiveness analyses of preventing osteoporotic fractures

This review was aimed at the evolution of health economic models used in evaluations of clinical approaches aimed at preventing osteoporotic fractures. Models have improved, with medical continuance becoming increasingly recognized as a contributor to health and economic outcomes, as well as advancements in epidemiological data. Model-based health economic evaluation studies are increasingly used to investigate the cost-effectiveness of osteoporotic fracture preventions and treatments. The objective of this study was to carry out a systematic review of the evolution of health economic models used in the evaluation of osteoporotic fracture preventions. Electronic searches within MEDLINE and EMBASE were carried out using a predefined search strategy. Inclusion and exclusion criteria were used to select relevant studies. References listed of included studies were searched to identify any potential study that was not captured in our electronic search. Data on country, interventions, type of fracture prevention, evaluation perspective, type of model, time horizon, fracture sites, expressed costs, types of costs included, and effectiveness measurement were extracted. Seventy-four models were described in 104 publications, of which 69% were European. Earlier models focused mainly on hip, vertebral, and wrist fracture, but later models included multiple fracture sites (humerus, pelvis, tibia, and other fractures). Modeling techniques have evolved from simple decision trees, through deterministic Markov processes to individual patient simulation models accounting for uncertainty in multiple parameters. Treatment continuance has been increasingly taken into account in the models in the last decade. Models have evolved in their complexity and emphasis, with medical continuance becoming increasingly recognized as a contributor to health and economic outcomes. This evolution may be driven in part by the desire to capture all the important differentiating characteristics of medications under scrutiny, as well as the advancement in epidemiological data relevant to osteoporosis fractures.

The cost effectiveness of teriparatide as a first-line treatment for glucocorticoid-induced and postmenopausal osteoporosis patients in Sweden

Background

This paper presents the model and results to evaluate the use of teriparatide as a first-line treatment of severe postmenopausal osteoporosis (PMO) and Glucocorticoid-induced osteoporosis (GIOP). The study’s objective was to determine if teriparatide is cost effective against oral bisphosphonates for two large and high risk cohorts.

Methods

A computer simulation model was created to model treatment, osteoporosis related fractures, and the remaining life of PMO and GIOP patients. Natural mortality and additional mortality from osteoporosis related fractures were included in the model. Costs for treatment with both teriparatide and oral bisphosphonates were included. Drug efficacy was modeled as a reduction to the relative fracture risk for subsequent osteoporosis related fractures. Patient health utilities associated with age, gender, and osteoporosis related fractures were included in the model. Patient costs and utilities were summarized and incremental cost-effectiveness ratios (ICERs) for teriparatide versus oral bisphosphonates and teriparatide versus no treatment were estimated.

For each of the PMO and GIOP populations, two cohorts differentiated by fracture history were simulated. The first contained patients with both a historical vertebral fracture and an incident vertebral fracture. The second contained patients with only an incident vertebral fracture. The PMO cohorts simulated had an initial Bone Mineral Density (BMD) T-Score of −3.0. The GIOP cohorts simulated had an initial BMD T-Score of −2.5.

Results

The ICERs for teriparatide versus bisphosphonate use for the one and two fracture PMO cohorts were €36,995 per QALY and €19,371 per QALY. The ICERs for teriparatide versus bisphosphonate use for the one and two fracture GIOP cohorts were €20,826 per QALY and €15,155 per QALY, respectively.

Conclusions

The selection of teriparatide versus oral bisphosphonates as a first-line treatment for the high risk PMO and GIOP cohorts evaluated is justified at a cost per QALY threshold of €50,000.

Effect of dietary calcium on spinal bone fusion in an ovariectomized rat model

OBJECTIVE

To evaluate the effect of calcium supplementation on spinal bone fusion in ovariectomized (OVX) rats.

METHODS

Sixteen female Sprague Dawley rats underwent bilateral ovariectomy at 12 weeks of age to induce osteoporosis and were randomly assigned to two groups : control group (n=8) and calcium-supplemented group (OVX-Ca, n=8). Autologous spinal bone fusion surgery was performed on both groups 8 weeks later. After fusion surgery, the OVX-Ca group was supplemented with calcium in drinking water for 8 weeks. Blood was obtained 4 and 8 weeks after fusion surgery. Eight weeks after fusion surgery, the rats were euthanized and the L4-5 spine removed. Bone fusion status and fusion volume were evaluated by manual palpation and three-dimensional computed tomography.

RESULTS

The mean fusion volume in the L4-5 spine was significantly greater in the OVX-Ca group (71.80±8.06 mm(3)) than in controls (35.34±8.24 mm(3)) (p<0.01). The level of osteocalcin, a bone formation marker, was higher in OVX-Ca rats than in controls 4 weeks (610.08±10.41 vs. 551.61±12.34 ng/mL) and 8 weeks (552.05±19.67 vs. 502.98±22.76 ng/mL) after fusion surgery (p<0.05). The level of C-terminal telopeptide fragment of type I collagen, a bone resorption marker, was significantly lower in OVX-Ca rats than in controls 4 weeks (77.07±12.57 vs. 101.75±7.20 ng/mL) and 8 weeks (69.58±2.45 vs. 77.15±4.10 ng/mL) after fusion surgery (p<0.05). A mechanical strength test showed that the L4-5 vertebrae in the OVX-Ca group withstood a 50% higher maximal load compared with the controls (p<0.01).

CONCLUSION

Dietary calcium given to OVX rats after lumbar fusion surgery improved fusion volume and mechanical strength in an ovariectomized rat model.