Dual-energy X-ray Absorptiometry Monitoring with Trabecular Bone Score: 2019 ISCD Official Position.

Trabecular bone score (TBS) is a textural index that evaluates pixel gray-level variations in the lumbar spine image by dual-energy X-ray absorptiometry. It provides an indirect assessment of trabecular microarchitecture that is an independent predictor of fracture risk. TBS does not appear to be clinically useful to monitor the skeletal effects of bisphosphonates and denosumab, but is potentially useful as a component of monitoring the skeletal effects of teriparatide and abaloparatide. The least significant change (LSC) for TBS can be conservatively estimated to be about 5.8% (the largest LSC in published data) or calculated by a dual-energy X-ray absorptiometry facility using the same methodology that is used for bone mineral density (BMD) precision assessment to calculate BMD LSC. A review of the best available evidence at the 2019 ISCD Position Development Conference concluded that the role of TBS in monitoring antiresorptive therapy is unclear and that TBS is potentially useful for monitoring anabolic therapy. For patients treated with teriparatide or abaloparatide, a statistically significant increase in TBS may represent a clinically meaningful improvement in trabecular structure. A significant decrease of TBS may represent a worsening of trabecular structure, suggesting the need for further clinical assessment and possible change in treatment strategies. Since BMD measures bone quantity and TBS measures bone quality, these tests can be considered complementary in assessing fracture risk and response to therapy in appropriate patients.

Non-BMD DXA measurements of the hip.

Hip fracture is one of the most serious complications of osteoporosis. More than 50% of hip and other fractures occur in patients without densitometric osteoporosis. Therefore, areal bone mineral density (aBMD) may not be the best way to assess fracture risk. In order to improve assessment of fracture risk, many other approaches have been taken. At the present time, the Fracture Risk Algorithm (FRAX©) is one of the most notable ways to improve assessment of fracture risk. However, since early in the initiation of the dual energy x-ray absorptiometry (DXA) era, several non-BMD DXA approaches to the assessment of hip fracture risk have been proposed. This review will cover some of those methodologies, including hip-axis length (HAL), hip-structural analysis (HSA), finite element analysis (FEA) by DXA, and body composition of the thigh by DXA (BCT). These methods have been utilized in models of hip fracture occurrence and in pharmacological clinical trials. How they should be used in clinical practice or if they should be used in clinical practice is more of an issue. In addition, we will discuss the recent proposal of the use of Long Femur Scan Field in the effort to diagnose atypical femoral fractures.

Stress fractures about the tibia, foot, and ankle.

In competitive athletes, stress fractures of the tibia, foot, and ankle are common and lead to considerable delay in return to play. Factors such as bone vascularity, training regimen, and equipment can increase the risk of stress fracture. Management is based on the fracture site. In some athletes, metabolic workup and medication are warranted. High-risk fractures, including those of the anterior tibial diaphysis, navicular, proximal fifth metatarsal, and medial malleolus, present management challenges and may require surgery, especially in high-level athletes who need to return to play quickly. Noninvasive treatment modalities such as pulsed ultrasound and extracorporeal shock wave therapy may have some benefit but require additional research.

Peripheral dual-energy X-ray absorptiometry in the management of osteoporosis: the 2007 ISCD Official Positions.

Peripheral assessment of bone density using photon absorptiometry techniques has been available for over 40 yr. The initial use of radio-isotopes as the photon source has been replaced by the use of X-ray technology. A wide variety of models of single- or dual-energy X-ray measurement tools have been made available for purchase, although not all are still commercially available. The Official Positions of the International Society for Clinical Densitometry (ISCD) have been developed following a systematic review of the literature by an ISCD task force and a subsequent Position Development Conference. These cover the technological diversity among peripheral dual-energy X-ray absorptiometry (pDXA) devices; define whether pDXA can be used for fracture risk assessment and/or to diagnose osteoporosis; examine whether pDXA can be used to initiate treatment and/or monitor treatment; provide recommendations for pDXA reporting; and review quality assurance and quality control necessary for effective use of pDXA.

Prescreening tools to determine who needs DXA.

Clinical decision rules (CDRs) are designed to help physicians practice better. A number of CDRs to assist in identifying women with low bone mass have been developed since the mid 1990s, including SCORE, OST (OSTA), OSIRIS, SOFSURF, NOF, ABONE, pBW, ORAI, and weight-only-EPIDOS (which we have termed WO-E). This review discusses these CDRs in terms of development and validation cohorts and their sensitivity and specificity. The sensitivities of the available CDRs exceed 80% and specificities are about 50%. After much analysis, it appears that most experts prefer OST for its simplicity and SCORE for its flexibility, but there is no consensus on what risk factors to use in the CDRs and what regions of interest (spine, total hip, femoral neck, or a combination) to test with dual-energy x-ray absorptiometry (DXA). Because of the lack of consensus, there are barriers to the clinical application of these CDRs. Agreement on a single CDR for worldwide use is required to optimally fulfill the objective of identifying low bone mass.

Detection of vertebral fractures.

Despite the importance of vertebral compression fractures, there is much that remains uncertain. There is no "gold standard" for the definition which has led to epidemiologic and study differences. Height loss is a way to suspect vertebral fractures but it has its own issues. There are multiple radiographic systems for defining vertebral fractures, both prevalent and incident; risk factors for prevalent fractures have already been delineated. Recent studies have elucidated the risk factors for incident vertebral fractures including age, low weight, late menarche, lower bone mineral density, history of vertebral and nonvertebral fractures, smoking, and use of a walking aid. Fan beam densitometers have had improving ability to image the spine, a procedure now known as vertebral fracture assessment (VFA). Recently (in the United States) a CPT code and reimbursement was established. Yet, many vertebral fractures go undiagnosed, diagnosed but unreported, or reported but not utilized in patient care. Because of this, the International Osteoporosis Foundation developed a Vertebral Fracture Initiative for radiologists and the International Society for Clinical Densitometry began a VFA course. Both teaching programs use the semi-quantitative assessment of Genant to aid the radiologists and clinicians in detecting vertebral fractures.

Combination teriparatide and raloxifene therapy for postmenopausal osteoporosis: results from a 6-month double-blind placebo-controlled trial.

UNLABELLED: We compared combination treatment with teriparatide plus raloxifene with teriparatide alone in women with postmenopausal osteoporosis in a 6-month double-blind, placebo-controlled trial that measured biochemical markers of bone turnover and BMD. Markers of bone formation and spine BMD increased similarly with teriparatide alone and combination therapy. However, combination therapy induced a significantly smaller increase in bone resorption versus teriparatide alone and significantly increased total hip BMD versus baseline. INTRODUCTION: The effects of combining two approved treatments for osteoporosis with different modes of action were examined by comparing teriparatide [rhPTH(1-34)] monotherapy with combination teriparatide and raloxifene therapy. MATERIALS AND METHODS: A 6-month randomized, double-blind trial comparing teriparatide plus raloxifene (n = 69) versus teriparatide plus placebo (n = 68) was conducted in postmenopausal women with osteoporosis. RESULTS: Bone formation (N-terminal propeptide of type 1 collagen [PINP]) increased similarly in both treatment groups. However, the increase in bone resorption (serum C-terminal telopeptide of type I collagen [CTx]) in the combination group was significantly smaller than in the teriparatide-alone group (p = 0.015). Lumbar spine BMD significantly increased 5.19 +/- 0.67% from baseline in the teriparatide-alone group. In the combination group, lumbar spine (6.19 +/- 0.65%), femoral neck (2.23 +/- 0.64%), and total hip (2.31 +/- 0.56%) BMD significantly increased from baseline to study endpoint, and the increase in total hip BMD was significantly greater than in the teriparatide-alone group (p = 0.04). In the teriparatide-alone group, mean serum calcium levels increased from baseline to endpoint (0.30 +/- 0.06 mg/dl, p < 0.001), whereas mean serum phosphate remained unchanged. In the combination group, mean serum calcium was unchanged, and mean serum phosphate decreased (-0.20 +/- 0.06 mg/dl, p < 0.001) from baseline to endpoint. Changes in serum calcium (p < 0.001) and phosphate (p < 0.004) were significantly different between treatment groups. The safety profile of combination therapy was similar to teriparatide alone. CONCLUSIONS: Combination therapy increased bone formation to a similar degree as teriparatide alone. However, the increase in bone resorption was significantly less and total hip BMD significantly increased for combination therapy compared with teriparatide alone. Combination treatment with raloxifene may thus enhance the bone forming effects of teriparatide. Further studies over longer treatment duration that include fracture endpoints are necessary to fully ascertain the clinical significance of combination raloxifene plus teriparatide therapy in postmenopausal osteoporosis.