Periprosthetic fractures are osteoporotic fractures: missed opportunities for osteoporosis diagnosis.

Joint replacement surgery is common in older adults, leading to increasing periprosthetic fracture (PPFx) occurrence. We reviewed all PPFx seen over a 4-year period at an academic hospital. Clinical osteoporosis could be diagnosed based on existing data in 104 (67%) at the time of PPFx. Periprosthetic fractures are generally osteoporosis-related. PURPOSE: Periprosthetic fractures (PPFx) cause morbidity, mortality, and cost. This study's purpose was to describe osteoporosis-related data available at the time of PPFx. METHODS: The electronic medical record (EMR) of PPFx patients seen over 4 years in a university orthopedic practice were reviewed. Demographic data and osteoporosis relevant parameters were collected. Prior DXA studies were reviewed, and L1 Hounsfield unit (HU) measurements were performed on CT scans obtained within 2 years before PPFx. Clinical osteoporosis was defined as prior diagnosis, prescribed osteoporosis treatment, T-score ≤ - 2.5, HU ≤ 100, or prior fracture. RESULTS: Records of 156 PPFx patients (115 F/41 M), mean (SD) age 75.4 (11.9), were reviewed. Almost all 153/156 (98%) of these fractures were femoral. Falls caused 139 (89%); 12 (8%) were spontaneous. Mean time post-arthroplasty was 7.9 (6.3) years. Prior fragility fracture(s) occurred in 72 (46%); 14 were PPFx. Osteoporosis was previously diagnosed in 45 (29%) and medications prescribed in 41 (26%). Prior to PPFx, DXA data were available in 62, mean (SD) lowest T-score was - 1.9 (0.9) and was ≤ - 2.5 in 19. CT data were available in 46; mean (SD) L1 HU was 79.0 (29.4) and was ≤ 100 in 35. Based on existing data, clinical osteoporosis could have been diagnosed in 104 (67%) at the time of PPFx. CONCLUSION: Periprosthetic fractures are osteoporosis-related. They occur in older adults, often female, and result from falls; BMD, when assessed, is low. Data available at the time of PPFx often allows osteoporosis diagnosis; this should prompt evaluation and pharmacologic treatment consideration.

Systemic Osteoporosis and Osteopenia Among Periprosthetic Fractures After Total Hip Arthroplasty.

BACKGROUND: Most periprosthetic fractures following total hip arthroplasty (THA) are fragility fractures that qualify patients for osteoporosis diagnoses. However, it remains unknown how many patients were diagnosed who had osteoporosis before injury or received the proper evaluation, diagnosis, and treatment after injury. METHODS: We identified 171 Vancouver B2 (109) and B3 (62) periprosthetic femur fractures treated with a modular fluted tapered stem from 2000 to 2018 at one institution. The mean patient age was 75 years (range, 35 to 94), 50% were women, and the mean BMI was 29 (range, 17 to 60). We identified patients who had osteoporosis or osteopenia diagnoses, a fracture risk assessment tool (FRAX), bone mineral density (BMD) testing, an endocrinology consult, and osteoporosis medications. Age-appropriate BMD testing was defined as no later than one year after the recommended ages of 65 (women) or 70 years (men). The mean follow-up was 11 years (range, 4 to 21). RESULTS: Falls from standing height caused 94% of fractures and thus, by definition, qualified as osteoporosis-defining events. The prevalence of osteoporosis diagnosis increased from 20% before periprosthetic fracture to 39% after (P < 0.001). The prevalence of osteopenia diagnosis increased from 13% before the fracture to 24% after (P < 0.001). The prevalence of either diagnosis increased from 24% before fracture to 44% after (P < 0.001). No patients had documented FRAX scores before fracture, and only 2% had scores after. The prevalence of BMD testing was 21% before fracture and 22% after (P = 0.88). By the end of the final follow-up, only 16% had received age-appropriate BMD testing. The proportion of patients who had endocrinology consults increased from 6% before the fracture to 25% after (P < 0.001). The proportion on bisphosphonate therapy was 19% before fracture and 25% after (P = 0.08). CONCLUSIONS: Although most periprosthetic fractures following THA are fragility fractures that qualify patients for osteoporosis diagnoses, there remain major gaps in diagnosis, screening, endocrinology follow-up, and treatment. Like non-arthroplasty fragility fractures, a systematic approach is needed after periprosthetic fractures.

Periprosthetic fractures: an unrecognized osteoporosis crisis.

Total joint replacement is common and increasing. Many of these patients have low bone mineral density preoperatively, and arthroplasty leads to bone loss. As falls are common before and after arthroplasty, it is unsurprising that periprosthetic fractures, defined as those associated with an orthopedic device, whether a joint replacement or other internal fixation devices, are not rare. These fractures engender morbidity and mortality comparable to osteoporosis-related hip fractures but remain largely unrecognized and untreated by osteoporosis/metabolic bone disease clinicians. Indeed, recent osteoporosis guidelines are silent regarding periprosthetic fractures. The purposes of this clinical review are to briefly describe the epidemiology of arthroplasty procedures and periprosthetic fractures, raise awareness that these fractures are osteoporosis-related, and suggest approaches likely to reduce their occurrence. Notably, bone health evaluation is essential following the occurrence of a periprosthetic fracture to reduce subsequent fracture risk. Importantly, in addition to such secondary fracture prevention, primary prevention, i.e., bone health assessment and optimization prior to elective orthopedic procedures, is appropriate.

MRI-based vertebral bone quality score: relationship with age and reproducibility.

Vertebral bone quality (VBQ) score is an opportunistic measure of bone mineral density using routine preoperative MRI in spine surgery. VBQ score positively correlates with age and is reproducible across serial scans. However, extrinsic factors, including MRI machine and protocol, affect the VBQ score and must be standardized. PURPOSE: The purposes of this study were to determine whether VBQ score increased with age and whether VBQ remained consistent across serial MRI studies obtained within 3 months. METHODS: This retrospective study evaluated 136 patients, age 20-69, who received two T1-weighted lumbar MRI within 3 months of each other between January 2011 and December 2021. VBQ(L1-4) score was calculated as the quotient of L1-L4 signal intensity (SI) and L3 cerebral spinal fluid (CSF) SI. VBQ(L1) score was calculated as the quotient of L1 SI and L1 CSF SI. Regression analysis was performed to determine correlation of VBQ(L1-4) score with age. Coefficient of variation (CV) was used to determine reproducibility between VBQ(L1-4) scores from serial MRI scans. RESULTS: One hundred thirty-six patients (mean ± SD age 44.9 ± 12.5 years; 53.7% female) were included in this study. Extrinsic factors affecting the VBQ score included patient age, MRI relaxation time, and specific MRI machine. When controlling for MRI relaxation/echo time, the VBQ(L1-4) score was positively correlated with age and had excellent reproducibility in serial MRI with CV of 0.169. There was excellent agreement (ICC > 0.9) of VBQ scores derived from the two formulas, VBQ(L1) and VBQ(L1-4). CONCLUSION: Extrinsic factors, including MRI technical factors and age, can impact the VBQ(L1-4) score and must be considered when using this tool to estimate bone mineral density (BMD). VBQ(L1-4) score was positively correlated with age. Reproducibility of the VBQ(L1-4) score across serial MRI is excellent especially when controlling for technical factors, supporting use of the VBQ score in estimating BMD. The VBQ(L1) score was a reliable alternative to the VBQ(L1-4) score.

Proposed bone health screening protocol to identify total knee arthroplasty patients for preoperative DXA.

This study evaluates a novel, simple bone health screening protocol composed of patient sex, age, fracture history, and FRAX risk to identify total knee arthroplasty patients for preoperative DXA. Findings supported effectiveness, with sensitivity of 1.00 (CI 0.92-1.00) and specificity of 0.54 (CI 0.41-0.68) when evaluating for clinical osteoporosis. PURPOSE: Bone health optimization is a process where osteoporotic patients are identified, evaluated via modalities such as dual-energy X-ray absorptiometry (DXA), and treated when indicated. There are currently no established guidelines to determine who needs presurgical DXA. This study evaluates the effectiveness of a simple screening protocol to identify TKA patients for preoperative DXA. METHODS: This prospective cohort study began on September 1, 2019, and included 100 elective TKA patients. Inclusion criteria were ≥ 50 years and primary TKA. All patients obtained routine clinical DXA. The screening protocol defining who should obtain DXA included meeting any of the following: female ≥ 65, male ≥ 70, fracture history after age 50, or FRAX major osteoporotic fracture risk without bone mineral density (BMD) adjustments ≥ 8.4%. Osteoporosis was defined by the World Health Organization (WHO) criteria (T-score ≤ - 2.5) or clinically (T-score ≤ - 2.5, elevated BMD-adjusted FRAX risk, or prior hip/spine fracture). Sensitivity and specificity were calculated. RESULTS: The study included 68 females and 32 males, mean age 67.2 ± 7.7. T-score osteoporosis was observed in 16 patients while 43 had clinical osteoporosis. Screening criteria recommending DXA was met by 69 patients. Screening sensitivity was 1.00 (CI 0.79-1.00) and specificity was 0.37 (CI 0.27-0.48) for identifying patients with T-score osteoporosis. Similar sensitivity of 1.00 (CI 0.92-1.00) and specificity of 0.54 (CI 0.41-0.68) were found for clinical osteoporosis. CONCLUSIONS: A simple screening protocol identifies TKA patients with T-score and clinical osteoporosis for preoperative DXA with high sensitivity in this prospective cohort study.

Intraoperative physician assessment of bone: correlation to bone mineral density.

This study evaluated the intraoperative physician assessment (IPA) of bone status at time of total knee arthroplasty. IPA was highly correlated with distal femur and overall bone mineral density. When IPA identifies poor bone status, formal bone health assessment is indicated. PURPOSE: Intuitively, intraoperative physician assessment (IPA) would be an excellent measure of bone status gained through haptic feedback during bone preparation. However, no studies have evaluated the orthopedic surgeon's ability to do so. This study's purpose, in patients undergoing total knee arthroplasty (TKA), was to relate IPA with (1) the lowest bone mineral density (BMD) T-score at routine clinical sites; and (2) with distal femur BMD. METHODS: Seventy patients undergoing TKA by 3 surgeons received pre-operative DXA. Intraoperatively, bone quality was assessed on a 5-point scale (1 excellent to 5 poor) based on tactile feedback to preparation. Demographic data, DXA results, and IPA score between surgeons were compared by factorial ANOVA. Lowest T-score and distal femur BMD were associated with IPA using Spearman's correlation. RESULTS: The mean (SD) age and BMI were 65.8 (7.6) years and 31.4 (5.1) kg/m2, respectively. Patient demographic data, BMD, and IPA (mean [SD] = 2.74 [1.2]) did not differ between surgeons. IPA correlated with the lowest T-score (R = 0.511) and distal femur BMD (R = 0.603-0.661). Based on the lowest T-score, no osteoporotic patients had an IPA above average, and none with normal BMD was classified as having poor bone. CONCLUSIONS: IPA is highly correlated with local (distal femur) and overall BMD. This study supports the International Society for Clinical Densitometry position that surgeon concern regarding bone quality should lead to bone health assessment. As IPA is comparable between surgeons, it is logical this can be widely applied by experienced orthopedic surgeons. Future studies evaluating IPA at other anatomic sites are indicated.

Advances in Osteoporosis Therapy: Focus on Osteoanabolic Agents, Secondary Fracture Prevention, and Perioperative Bone Health.

PURPOSE OF REVIEW: This review summarizes recently published data and other developments around osteoanabolic osteoporosis therapies in patients with very high fracture risk, including those undergoing bone-related surgery. RECENT FINDINGS: Two osteoanabolic agents, abaloparatide and romosozumab, were recently approved for treatment of patients with osteoporosis at high fracture risk. These agents, along with teriparatide, are valuable for primary and secondary fracture prevention. Orthopedic surgeons are well positioned to facilitate secondary fracture prevention via referrals to fracture liaison services or other bone health specialist colleagues. This review aims to help surgeons understand how to identify patients with sufficiently high fracture risk to warrant consideration of osteoanabolic therapy. Recent evidence around the perioperative use and potential benefits of osteoanabolic agents in fracture healing and other orthopedic settings (e.g., spinal fusion and arthroplasty) in individuals with osteoporosis is also discussed. Osteoanabolic agents should be considered for patients with osteoporosis at very high fracture risk, including those with prior osteoporotic fractures and those with poor bone health who are undergoing bone-related surgery.

Humeral BMD can be Measured With DXA and Is Lower in the Surgical Arm After Total Shoulder Arthroplasty.

BACKGROUND: As arthroplasty leads to bone loss, we hypothesized that humeral bone mineral density (BMD) is lower after total shoulder arthroplasty (TSA) in the operative versus non-operative arm. However, there is no clinical approach to measure humeral BMD with dual-energy x-ray absorptiometry (DXA). The purposes of this pilot study were to develop DXA methodology to measure humerus BMD, propose humerus regions of interest (ROIs), compare TSA BMD to the non-operative arm, correlate humeral BMD with standard sites, and evaluate measurement reproducibility. METHODOLOGY: Thirty-eight adults 1-5 years post-TSA had standard clinical DXA scans plus full humerus scans using the atypical femur fracture feature; precision was assessed in a subset (n = 32). Six custom ROIs were used to measure BMD throughout the humerus. Radius and humeral BMD were compared between arms by paired t-test and correlated ipsilaterally using Pearson's Correlation. Custom ROI BMD precision was assessed using the International Society for Clinical Densitometry (ISCD) advanced precision calculator. RESULTS: Study included 38 subjects (24M/14F), with mean (SD) age and time post-surgery of 69.6 (7.7) years and 2.5 (1.3) years respectively. BMD was lower (p < 0.01) at all custom humerus sites (3.8% to 8.2%) on the surgical side but not different at radius sites. Humeral BMD correlated positively with ipsilateral ultra-distal and 1/3 radius (r = 0.54 to 0.86; p < 0.05). Custom BMD precision (%CV) ranged from 6.0-16.0%. CONCLUSIONS: Humerus BMD can be measured using DXA and is lower in the TSA arm. Radius BMD correlated with humeral BMD but was not lower in the surgical arm. BMD precision was worse than usual clinical sites; use of software optimized for the femur is a notable limitation and likely contributes to suboptimal precision. Further study to assess the clinical utility of humeral BMD is needed. Automation and optimization of these measurements should improve precision.

Femur and Tibia BMD Measurement in Elective Total Knee Arthroplasty Candidates.

Distal femur BMD declines ∼20% following total knee arthroplasty (TKA) potentially leading to adverse outcomes. BMD knowledge before and following TKA might allow interventions to optimize outcomes. We hypothesized that distal femur and proximal tibial BMD could be reproducibly measured with existing DXA technology. Elective TKA candidates were enrolled and standard clinical DXA plus bilateral PA and lateral knee scans acquired. Manual regions of interest (ROIs) were placed at distal femur and proximal tibia sites based on required TKA machining and periprosthetic fracture location. Intra- and inter-rater BMD reliability was assessed by intra-class correlation (ICC). Custom and standard proximal femur BMD were correlated by linear regression and paired t test evaluated BMD differences between planned surgical and contralateral side. One hundred subjects (68F/32M), mean (SD) age and BMI of 67.2 (7.7) yr and 30.8 (4.8) kg/m2 were enrolled. Lowest clinical BMD T-score was < -1.0 in 65% and ≤ -2.5 in 16%; 34 had prior fracture. BMD reproducibility at all custom ROIs was excellent; ICC > 0.96. Mean BMD at custom ROIs ranged from 0.903 to 1.346 g/cm2 in the PA projection and 0.891 to 1.429 g/cm2 in the lateral. Lower BMD values were observed at the proximal tibia, while the higher measurements were at the femur condyle. Custom knee ROI BMD was highly correlated (p < 0.0001) with total and femur neck with better correlation at ROIs adjacent to the joint (R2 = 0.62-0.67, 0.49-0.55 respectively). In those without prior TKA (n = 76), mean BMD was lower (2.8%-6.6%; p < 0.05) in the planned surgical leg at all custom ROIs except the PA tibial regions. Individual variability was present with 82% having a custom ROI with lower BMD (up to 53%) in the planned operative leg. Distal femur and proximal tibial BMD can be measured using custom ROIs with good reproducibility. Suboptimal bone status is common in TKA candidates and distal femur/proximal tibia BMD is often lower on the planned operative side. Routine distal femur/proximal tibial BMD measurement might assist pre-operative interventions, surgical decision-making, subsequent care and outcomes. Studies to evaluate these possibilities are indicated.

Proceedings of the 2021 Santa Fe Bone Symposium: Advances in the Management of Osteoporosis and Metabolic Bone Diseases.

The 2021 Virtual Santa Fe Bone Symposium was held August 5-8, with over 300 registered attendees from throughout the USA, and at least 18 other countries. This annual meeting focuses on applying advances in basic science and clinical research to the care of patients with osteoporosis and those with inherited and acquired disorders of bone metabolism. Participants represented a broad range of medical disciplines with an interest in skeletal diseases. These included physicians of many specialties and practice settings, fellows, advanced practice providers, fracture liaison service (FLS) coordinators, clinical researchers, and bone density technologists. There were lectures, case presentations, and panel discussions, all followed by interactive discussions. Breakout sessions included an FLS workshop, Bone Health TeleECHO workshop, special interest groups, meet-and-greet the faculty, and satellite symposia. The agenda covered topics of interest such as strategies for the use of osteoanabolic therapy, prevention of periprosthetic fractures, management of atypical femur fractures, what we know and don't know about vitamin D, advances in the use of dual-energy X-ray absorptiometry in the assessment of skeletal health, controversies and conundrums in osteoporosis care, skeletal health in transgender patients, management of patients with hypophosphatasia and hypophosphatemia, and treat-to-target approaches for managing patients with osteoporosis. The Proceedings of the 2021 Virtual Santa Fe Bone Symposium consists of highlights of each presentation with current strategies for optimizing the care of patients with skeletal disorders.

Rationale for Bone Health Optimization in Patients Undergoing Orthopaedic Surgery.

Osteoporosis is common, affecting more than 40 million people, and is associated with increased fracture risk, loss of independence, chronic pain, and disability. Osteoporosis is underdiagnosed and undertreated even after fracture where secondary fracture prevention has been shown to be cost effective in reducing further fracture risk and mortality. Osteoporosis is also undiagnosed in patients undergoing orthopaedic and spine surgery in up to one-third of cases and negatively affects outcomes, need for revision surgery, and risk of complications. The diagnosis of osteoporosis was previously based on bone mineral density; however, recent clinical definitions include T-scores less than -2.5, the presence of hip and spine fractures, and high fracture risk. Surgeons should adopt bone health optimization for elective surgery. This program screens patients to determine whether a bone mineral density test is indicated and provides counseling for nutritional supplements, elimination of toxins, fall risk assessment, and education regarding bone health. Following assessment, patients meeting the criteria for osteoporosis are referred to a bone health specialist or a fracture liaison program. Both antiresorptive and anabolic antiosteoporotic medications appear effective at improving outcomes and reducing complications of orthopaedic and spine surgery, although a delay in surgery may be required.

The Basics of Bone Physiology, Healing, and Osteoporosis.

Osteoporosis is a skeletal condition characterized by decreased bone mineral density and poor bone quality with resultant greater fracture risk. There has been a focus on bone mineral density deficiency, which is easily measured with dual-energy x-ray absorptiometry and managed with pharmaceutic medications. More recently, impaired bone quality independent of bone mineral density has been recognized as a potential cause of fragility fracture and poor bone healing. Many conditions lead to poor bone quality; the most common is vitamin D deficiency and others are genetic causes and other nutritional deficits. In addition, the cellular and molecular changes associated with osteoporosis are being investigated and are potential targets for treatment. Treatment of patients with poor bone health include nutritional supplementation with vitamin D and calcium, weight-bearing exercises, and antiosteoporotic medications when warranted. Antiosteoporotic medications include antiresorptive drugs such as diphosphonate and denosumab that inhibit osteoclastic bone resorption. Anabolic agents such as teriparatide, abaloparatide, and romosozumab stimulate osteoblastic differentiation and bone formation. All these agents are effective in reducing fracture risk.

Preoperative bone health assessment and optimization in spine surgery.

OBJECTIVE: The purpose of this investigation was to characterize the bone health in preoperative spine surgery patients. This information will provide a framework to understand the needs and methods for providing bone health optimization in elective spine surgery patients. METHODS: A retrospective study of 104 patients undergoing bone health optimization was performed. Patients were selected based on risk factors identified by the surgeon and suspected compromised bone health. Evaluation included history and examination, laboratory investigations, and bone mineral density (BMD) at 3 sites (femoral neck, lumbar spine, and radius). Patients' bone status was classified using WHO criteria and expanded criteria recommended by the National Osteoporosis Foundation (NOF). The 10-year Fracture Risk Assessment Tool (FRAX) scores of the hip and major osteoporotic fracture (MOF) were calculated with and without femoral neck BMD, with spine BMD, and with the trabecular bone score (TBS). Antiresorptive and anabolic agents were provided in accordance with meeting NOF criteria for treatment of osteoporosis. RESULTS: The mean patient age was 69.0 years, and 81% of patients were female. The mean historical height loss was 5.6 cm, and 54% of patients had a history of fracture. Secondary osteoporosis due to chronic renal failure, inflammatory arthritis, diabetes, and steroid use was common (51%). The mean 25-hydroxy vitamin D was 42.4 ng/ml and was normal in 81% of patients, with only 4 patients being deficient. The mean T-scores were -2.09 (SD 0.71) of the femoral neck, -0.54 (1.71) of the lumbar spine, and -1.65 (1.38) of the distal radius. These were significantly different. The 10-year FRAX MOF score was 20.7%, and that for hip fracture was 6.9% using the femoral neck BMD and was not significantly different without the use of BMD. The FRAX risk-adjusted score using the lumbar spine BMD and TBS was significantly lower than that for the hip. Osteoporosis was present in 32.1% according to WHO criteria compared with 81.6% according to NOF criteria. Antiresorptive medications were recommended in 31 patients and anabolic medications in 44 patients. CONCLUSIONS: Surgeons can reliably identify patients with poor bone health by using simple criteria, including historical height loss, history of fracture, comorbidities associated with osteoporosis, analysis of available imaging, and calculation of FRAX score without BMD. High-risk patients should have BMD testing and bone health assessment. In patients with osteoporosis, a comprehensive preoperative bone health assessment is recommended and, if warranted, pharmacological treatment should be started.

Regional improvements in lumbosacropelvic Hounsfield units following teriparatide treatment.

OBJECTIVE: Opportunistic Hounsfield unit (HU) determination from CT imaging has been increasingly used to estimate bone mineral density (BMD) in conjunction with assessments from dual energy x-ray absorptiometry (DXA). The authors sought to compare the effect of teriparatide on HUs across different regions in the pelvis, sacrum, and lumbar spine, as a surrogate measure for the effects of teriparatide on lumbosacropelvic instrumentation. METHODS: A single-institution retrospective review of patients who had been treated with at least 6 months of teriparatide was performed. All patients had at least baseline DXA as well as pre- and post-teriparatide CT imaging. HUs were measured in the pedicle, lamina, and vertebral body of the lumbar spine, in the sciatic notch, and at the S1 and S2 levels at three different points (ilium, sacral body, and sacral ala). RESULTS: Forty patients with an average age of 67 years underwent a mean of 20 months of teriparatide therapy. Mean HUs of the lumbar lamina, pedicles, and vertebral body were significantly different from each other before teriparatide treatment: 343 ± 114, 219 ± 89.2, and 111 ± 48.1, respectively (p < 0.001). Mean HUs at the S1 level for the ilium, sacral ala, and sacral body were also significantly different from each other: 124 ± 90.1, -10.7 ± 61.9, and 99.1 ± 72.1, respectively (p < 0.001). The mean HUs at the S2 level for the ilium and sacral body were not significantly different from each other, although the mean HU at the sacral ala (-11.9 ± 52.6) was significantly lower than those at the ilium and sacral body (p = 0.003 and 0.006, respectively). HU improvement occurred in most regions following teriparatide treatment. In the lumbar spine, the mean lamina HU increased from 343 to 400 (p < 0.001), the mean pedicle HU increased from 219 to 242 (p = 0.04), and the mean vertebral body HU increased from 111 to 134 (p < 0.001). There were also significant increases in the S1 sacral body (99.1 to 130, p < 0.05), S1 ilium (124 vs 165, p = 0.01), S1 sacral ala (-10.7 vs 3.68, p = 0.04), and S2 sacral body (168 vs 189, p < 0.05). CONCLUSIONS: There was significant regional variation in lumbar and sacropelvic HUs, with most regions significantly increasing following teriparatide treatment. The sacropelvic area had lower HU values than the lumbar spine, more regional variation, and a higher degree of correlation with BMD as measured on DXA. While teriparatide treatment resulted in HUs > 110 in the majority of the lumbosacral spine, the HUs in the sacral ala remained suggestive of severe osteoporosis, which may limit the effectiveness of fixation in this region.

Osteoporosis in spine surgery patients: what is the best way to diagnose osteoporosis in this population?

OBJECTIVE: The goal of this study was to compare different recognized definitions of osteoporosis in patients with degenerative lumbar spine pathology undergoing elective spinal fusion surgery to determine which patient population should be considered for preoperative optimization. METHODS: A retrospective review of patients in whom lumbar spine surgery was planned at 2 academic medical centers was performed, and the rate of osteoporosis was compared based on different recognized definitions. Assessments were made based on dual-energy x-ray absorptiometry (DXA), CT Hounsfield units (HU), trabecular bone score (TBS), and fracture risk assessment tool (FRAX). The rate of osteoporosis was compared based on different definitions: 1) the WHO definition (T-score ≤ -2.5) at total hip or spine; 2) CT HU of < 110; 3) National Bone Health Alliance (NBHA) guidelines; and 4) "expanded spine" criteria, which includes patients meeting NBHA criteria and/or HU < 110, and/or "degraded" TBS in the setting of an osteopenic T-score. Inclusion criteria were adult patients with a DXA scan of the total hip and/or spine performed within 1 year and a lumbar spine CT scan within 6 months of the physician visit. RESULTS: Two hundred forty-four patients were included. The mean age was 68.3 years, with 70.5% female, 96.7% Caucasian, and the mean BMI was 28.8. Fracture history was reported in 53.8% of patients. The proportion of patients identified with osteoporosis on DXA, HUs, NBHA guidelines, and the authors' proposed "expanded spine" criteria was 25.4%, 36.5%, 75%, and 81.9%, respectively. Of the patients not identified with osteoporosis on DXA, 31.3% had osteoporosis based on HU, 55.1% had osteoporosis with NBHA, and 70.4% had osteoporosis with expanded spine criteria (p < 0.05), with poor correlations among the different assessment tools. CONCLUSIONS: Limitations in the use of DXA T-scores alone to diagnose osteoporosis in patients with lumbar spondylosis has prompted interest in additional methods of evaluating bone health in the spine, such as CT HU, TBS, and FRAX, to inform guidelines that aim to reduce fracture risk. However, no current osteoporosis assessment was developed with a focus on improving outcomes in spinal surgery. Therefore, the authors propose an expanded spine definition for osteoporosis to identify a more comprehensive cohort of patients with potential poor bone health who could be considered for preoperative optimization, although further study is needed to validate these results in terms of clinical outcomes.

An Ion-Exchangeable MOF with Reversible Dehydration and Dynamic Structural Behavior (NH4 )2 [Zn2 (O3 PCH2 CH2 COO)2 ]⋠5 H2 O (BIRM-1).

(NH4 )2 [Zn2 (O3 PCH2 CH2 COO)2 ]⋅5 H2 O (BIRM-1) is a new metal phosphonate material, synthesized through a simple hydrothermal reaction between zinc nitrate and 3-phosphonopropionic acid, using urea and tetraethylammonium bromide as the reaction medium. In common with other metal-organic framework materials, BIRM-1 has a large three-dimensional porous structure providing potential access to a high internal surface area. Unlike most others, it has the advantage of containing ammonium cations within the pores and has the ability to undergo cation exchange. Additionally, BIRM-1 also exhibits a reversible dehydration behavior involving an amorphization-recrystallization cycle. The ability to undergo ion exchange and dynamic structural behavior are of interest in their own right, but also increase the range of potential applications for this material. Here the crystal structure of this new metal phosphonate and its ion exchange behavior with K+ as an exemplar are studied in detail, and its unusual structure-reviving property reported.

Use of Bone Health Evaluation in Orthopedic Surgery: 2019 ISCD Official Position.

This position development conference (PDC) Task Force examined the assessment of bone status in orthopedic surgery patients. Key questions included which orthopedic surgery patients should be evaluated for poor bone health prior to surgery and which subsets of patients are at high risk for poor bone health and adverse outcomes. Second, the reliability and validity of using bone densitometry techniques and measurement of specific geometries around the hip and knee before and after arthroplasty was determined. Finally, the use of computed tomography (CT) attenuation coefficients (Hounsfield units) to estimate bone quality at anatomic locations where orthopedic surgery is performed including femur, tibia, shoulder, wrist, and ankle were reviewed. The literature review identified 665 articles of which 198 met inclusion exclusion criteria and were selected based on reporting of methodology, reliability, or validity results. We recommend that the orthopedic surgeon be aware of established ISCD guidelines for determining who should have additional screening for osteoporosis. Patients with inflammatory arthritis, chronic corticosteroid use, chronic renal disease, and those with history of fracture after age 50 are at high risk of osteoporosis and adverse events from surgery and should have dual energy X-ray absorptiometry (DXA) screening before surgery. In addition to standard DXA, bone mineral density (BMD) measurement along the femur and proximal tibia is reliable and valid around implants and can provide valuable information regarding bone remodeling and identification of loosening. Attention to positioning, selection of regions of interest, and use of special techniques and software is required. Plain radiographs and CT provide simple, reliable methods to classify the shape of the proximal femur and to predict osteoporosis; these include the Dorr Classification, Cortical Index, and critical thickness. Correlation of these indices to central BMD is moderate to good. Many patients undergoing orthopedic surgery have had preoperative CT which can be utilized to assess regional quality of bone. The simplest method available on most picture archiving and communications systems is to simply measure a regions of interest and determine the mean Hounsfield units. This method has excellent reliability throughout the skeleton and has moderate correlation to DXA based on BMD. The prediction of outcome and correlation to mechanical strength of fixation of a screw or implant is unknown.

Executive Summary of the 2019 ISCD Position Development Conference on Monitoring Treatment, DXA Cross-calibration and Least Significant Change, Spinal Cord Injury, Peri-prosthetic and Orthopedic Bone Health, Transgender Medicine, and Pediatrics.

To answer important questions in the fields of monitoring with densitometry, dual-energy X-ray absorptiometry machine cross-calibration, monitoring, spinal cord injury, periprosthetic and orthopedic bone health, transgender medicine, and pediatric bone health, the International Society for Clinical Densitometry (ISCD) held a Position Development Conference from March 20 to 23, 2019. Potential topics requiring guidance were solicited from ISCD members in 2017. Following that, a steering committee selected, prioritized, and grouped topics into Task Forces. Chairs for each Task Force were appointed and the members were co-opted from suggestions by the Steering Committee and Task Force Chairs. The Task Forces developed key questions, performed literature searches, and came up with proposed initial positions with substantiating draft publications, with support from the Steering Committee. An invited Panel of Experts first performed a review of draft positions using a modified RAND Appropriateness Method with voting for appropriateness. Draft positions deemed appropriate were further edited and presented at the Position Development Conference meeting in an open forum. A second round of voting occurred after discussions to approve or reject the positions. Finally, a face-to-face closed session with experts and Task Force Chairs, and subsequent electronic follow-up resulted in 34 Official Positions of the ISCD approved by the ISCD Board on May 28, 2019. The Official Positions and the supporting evidence were submitted for publication on July 1, 2019. This paper provides a summary of the all the ISCD Adult and Pediatric Official Positions, with the new 2019 positions highlighted in bold.

Osteoporosis Is Common and Undertreated Prior to Total Joint Arthroplasty.

BACKGROUND: Osteoporosis is common in total joint arthroplasty (TJA) patients and likely contributes to the increasing incidence of periprosthetic fracture. Despite this, the prevalence of osteoporosis in patients undergoing elective TJA is inadequately studied. We hypothesize that preoperative osteoporosis is underrecognized and undertreated in the TJA population. The purpose of this study is to report preoperative osteoporosis screening rates and prevalence prior to TJA and rates of pharmacologic osteoporosis treatment in the TJA population. METHODS: This is a retrospective case series of 200 consecutive adults (106F, 94M) aged 48-92 years who underwent elective TJA (100 total hip, 100 total knee) at a single tertiary-care center. Charts were retrospectively reviewed to determine preoperative osteoporosis risk factors, prior dual-energy X-ray absorptiometry (DXA) testing, and prior osteoporosis pharmacotherapy. Fracture risk was estimated using the Fracture Risk Assessment Tool and the National Osteoporosis Foundation criteria for screening and treatment were applied to all patients. RESULTS: One hundred nineteen of 200 patients (59.5%) met criteria for DXA testing. Of these 119, 21 (17.6%) had DXA testing in the 2 years prior to surgery, and 33% had osteoporosis by T-score. Forty-nine patients (24.5%) met National Osteoporosis Foundation criteria for pharmacologic osteoporosis treatment, and 11 of these 49 received a prescription for pharmacotherapy within 6 months before or after surgery. CONCLUSION: One quarter of TJA patients meet criteria to receive osteoporosis medications, but only 5% receive therapy preoperatively or postoperatively. This lack of preoperative osteoporosis screening and treatment may contribute to periprosthetic fracture risk.

Unrecognized Osteoporosis Is Common in Patients With a Well-Functioning Total Knee Arthroplasty.

BACKGROUND: Peri-prosthetic fractures after total knee arthroplasty (TKA) are associated with poorer outcomes and high costs. We hypothesize that osteoporosis is under-recognized in the TKA population. The purpose of this study is to report osteoporosis prevalence in a healthy cohort of patients with well-functioning TKA and to compare prevalence between males and females. METHODS: This study is a cross-sectional study of 30 adults (15 males/15 females) aged 59-80 years without known bone health issues who volunteered to undergo routine dual-energy X-ray absorptiometry 2-5 years (average 3.2 ± 0.8) after primary unilateral TKA. These data plus clinical risk factors were used to estimate fracture risk via the Fracture Risk Assessment Tool and skeletal status (normal, osteopenic, osteoporotic) was determined based on the World Health Organization definition. The National Osteoporosis Foundation criteria for treatment were applied to all patients. RESULTS: Six of 30 (20%) patients had T-score ≤ -2.5. Eighteen of 30 (60%) patients had T-score between -1 and -2.5 and 6 (20%) patients had T-score ≥ -1. Five patients with normal or osteopenic bone mineral density (BMD) had occult vertebral fractures. Eleven of 30 (36.7%) patients met National Osteoporosis Foundation criteria for pharmacologic treatment. CONCLUSION: The prevalence of occult osteoporosis meeting treatment guidelines after TKA is substantial in this sample (36.7%). BMD and osteoporosis prevalence are similar between men and women. This underappreciated prevalence of osteoporosis may contribute to peri-prosthetic fracture risk. Arthroplasty surgeons and bone health specialists must be aware of post-operative changes in bone density. These data support the further study of post-operative osteoporosis and consideration of routine BMD screening after TKA. LEVEL OF EVIDENCE: III.