Stress fractures in elderly patients

Effect of age on ankle biomechanics and tibial compression during stair descent

BACKGROUND

Stress fracture is a concern among older adults, as age-related decrements in ankle neuromuscular function may impair their ability to attenuate tibial compressive forces experienced during daily locomotor tasks, such as stair descent. Yet, it is unknown if older adults exhibit greater tibial compression than their younger counterparts when descending stairs.

RESEARCH QUESTION

Do older adults exhibit differences in ankle biomechanics that alter their tibial compression during stair descent compared to young adults, and is there a relation between tibial compression and specific changes in ankle biomechanics?

METHODS

Thirteen young (18-25 years) and 13 older (> 65 years) adults had ankle joint biomechanics and tibial compression quantified during a stair descent. Discrete ankle biomechanics (peak joint angle and moment, and joint stiffness) and tibial compression (maximum and impulse) measures were submitted to an independent t-test, while ankle joint angle and moment, and tibial compression waveforms were submitted to an independent statistical parametric mapping t-test to determine group differences. Pearson correlation coefficients (r) determined the relation between discrete ankle biomechanics and tibial compression measures for all participants, and each group.

RESULTS

Older adults exhibited smaller maximum tibial compression (p = 0.004) from decreases in peak ankle joint angle and moment between 17 % and 34 % (p = 0.035), and 20-31 % of stance (p < 0.001) than young adults. Ankle biomechanics exhibited a negligible to weak correlation with tibial compression for all participants, with peak ankle joint moment and maximum tibial compression (r = -0.48 ± 0.32) relation the strongest. Older adults typically exhibited a stronger relation between ankle biomechanics and tibial compression (e.g., r = -0.48 ± 0.47 vs r = -0.27 ± 0.52 between peak ankle joint moment and maximum tibial compression).

SIGNIFICANCE

Older adults altered ankle biomechanics and decreased maximum tibial compression to safely execute the stair descent. Yet, specific alterations in ankle biomechanics could not be identified as a predictor of changes in tibial compression.

Atraumatic Bilateral Patella Fracture in Middle-Aged Female: A Rare Case Report

The patella is the largest sesamoid bone in the body and an important structure of the extensor apparatus which is under undue stress during flexion and extension of the knee. Bilateral fracture of the patella without trauma is a very rare event and may be multifactorial without a single cause. A repetitive stress reaction in a previously predisposed bone can be an important cause. We report a case of a 45-year-old female with a nontraumatic bilateral transverse patella fracture with loss of extensor mechanism. A stable surgical fixation for such a displaced fracture with a good rehabilitation program can lead to a good functional outcome.

Microstructural fatigue fracture behavior of glycated cortical bone

The current study aims to simulate fatigue microdamage accumulation in glycated cortical bone with increased advanced glycation end-products (AGEs) using a phase field fatigue framework. We link the material degradation in the fracture toughness of cortical bone to the high levels of AGEs in this tissue. We simulate fatigue fracture in 2D models of cortical bone microstructure extracted from human tibias. The results present that the mismatch between the critical energy release rate of microstructural features (e.g., osteons and interstitial tissue) can alter crack initiation and propagation patterns. Moreover, the high AGEs content through the increased mismatch ratio can cause the activation or deactivation of bone toughening mechanisms under cyclic loading. The fatigue fracture simulations also show that the lifetime of diabetic cortical bone samples can be dependent on the geometry of microstructural features and the mismatch ratio between the features. Additionally, the results indicate that the trapped cracks in cement lines in the diabetic cortical microstructure can prevent further crack growth under cyclic loading. The present findings show that alterations in the materials heterogeneity of microstructural features can change the fatigue fracture response, lifetime, and fragility of cortical bone with high AGEs contents. Cortical bone models are created from microscopy images taken from the cortical cross-section of human tibias. Increased glycation contents in the cortical bone sample can change the crack growth trajectories.

Advanced glycation and glycoxidation end products in bone

Hyperglycemia and oxidative stress, enhanced in diabetes and aging, result in excessive accumulation of advanced glycation and glycoxidation end products (AGEs/AGOEs) in bone. AGEs/AGOES are considered to be "the missing link" in explaining increased skeletal fragility with diabetes, aging, and osteoporosis where increased fracture risk cannot be solely explained by bone mass and/or fall incidences. AGEs/AGOEs disrupt bone turnover and deteriorate bone quality through alterations of organic matrix (collagen and non-collagenous proteins), mineral, and water content. AGEs and AGOEs are also associated with bone fragility in other conditions such as Alzheimer's disease, circadian rhythm disruption, and cancer. This review explains how AGEs and AGOEs accumulate in bone and impact bone quality and bone fracture, and how AGES/AGOEs are being targeted in preclinical and clinical investigations for inhibition or removal, and for prediction and management of diabetic, osteoporotic and insufficiency fractures.

Age and Female Sex Are Important Risk Factors for Stress Fractures: A Nationwide Database Analysis

BACKGROUND

Stress fractures are caused by micro-trauma due to repetitive stress on bone, common in active individuals and athletes. Previous studies demonstrate that the weightbearing bones of the lower extremities incur stress fractures most often, especially in women and older adults.

HYPOTHESIS

Prior literature does not quantify the difference in frequency of stress fractures among different genders, age groups, or body mass indices (BMIs). We hypothesized that older female patients would have higher rates of lower extremity stress fractures than male patients.

STUDY DESIGN

Epidemiological research.

LEVEL OF EVIDENCE

Level 3.

METHODS

Records of female and male patients with lower extremity stress fractures from 2010 to 2018 were identified from the PearlDiver administrative claims database using the International Classification of Diseases (ICD)-9/ICD-10 codes. Stress fractures were classified by ICD-10 diagnosis codes to the tibial bone, proximal femur, phalanges, and other foot bones. Comorbidities were incorporated into a regression analysis.

RESULTS

Of 41,257 stress fractures identified, 30,555 (70.1%) were in women and 10,702 (25.9%) were in men. Our sample was older (>60 years old) (37.3%) and not obese (BMI <30 kg/m², 37.1%). A greater proportion of female patients with stress fracture were older (P < 0.001) and had foot stress fractures (P < 0.001), while a greater proportion of male patients with stress fracture were younger than 19 years (P < 0.001) and had metatarsal (P < 0.001), hip (P = 0.002), and tibia stress fractures (P < 0.001).

CONCLUSION

Stress fractures commonly occur in women and older adults with low BMIs. Metatarsal and tibia stress fractures were the most common, and a greater proportion of women had foot stress fractures.

CLINICAL RELEVANCE

Our study examined the large-scale prevalence of different lower extremity stress fractures among a wide patient population sample of varying ages and BMIs. These findings can help clinicians identify active populations at greater risk for stress fracture injuries.

Bringing Mechanical Context to Image-Based Measurements of Bone Integrity

PURPOSE OF REVIEW

Image-based measurements of bone integrity are used to estimate failure properties and clinical fracture risk. This paper (1) reviews recent imaging studies that have enhanced our understanding of the mechanical pathways to bone fracture and (2) discusses the influence that inter-individual differences in image-based measurements may have on the clinical assessment of fracture risk RECENT FINDINGS: Increased tissue mineralization is associated with improved bone strength but reduced fracture toughness. Trabecular architecture that is important for fatigue resistance is less important for bone strength. The influence of porosity on bone failure properties is heavily dependent on pore location and size. The interaction of various characteristics, such as bone area and mineral content, can further complicate their influence on bone failure properties. What is beneficial for bone strength is not always beneficial for bone toughness or fatigue resistance. Additionally, given the large amount of imaging data that is clinically available, there is a need to develop effective translational strategies to better interpret non-invasive measurements of bone integrity.

Effect of ageing on microstructure and fracture behavior of cortical bone as determined by experiment and Extended Finite Element Method (XFEM)

Bone fracture is a severe health concern; therefore, understanding the causes of bone fracture are crucial. This paper investigates the microstructure and fracture behaviour of cadaveric cortical bone of two different groups (Young, n= 6; Aged, n=7). The microstructure is obtained from µ-CT images, and the material parameters are measured with nanoindentation. Fracture behaviour in transverse and longitudinal orientations is investigated experimentally and numerically. The results show that the Haversian canal (HC) size increases and the osteon wall thickness (OWT) decreases significantly in the aged group, whereas a nonsignificant difference is found in tissue properties. The crack initiation (J_ic) and crack growth (J_grow) toughness of the aged group are found to be significantly lower (p<0.01) than the young group in the transverse orientation; however, for the longitudinal orientation, only the value of J_ic in the aged group is found significantly lower. Further, a 4-phase XFEM (based on micro-CT image) model is developed to investigate the crack propagation behaviour in both orientations. For the transverse orientation, results show that in the aged group, the crack initially follows the cementline and then penetrates the osteon, whereas, in the young group, it propagates along the cementline. These results are in agreement with experimental results where the decrease in J_grow is more significant than the J_ic in the aged group. This study suggests that ageing leads to a larger HC and reduced OWT, which weakens the crack deflection ability and causes fragility fracture. Further, the XFEM results indicate that the presence of a small microcrack in the vicinity of a major crack tip causes an increase in the critical stress intensity factor.

Training Load Capacity, Cumulative Risk, and Bone Stress Injuries: A Narrative Review of a Holistic Approach

Bone stress injuries (BSIs) are a common orthopedic injury with short-term, and potentially long-term, effects. Training load capacity, influenced by risk factors, plays a critical role in the occurrence of BSIs. Many factors determine how one's body responds to repetitive loads that have the potential to increase the risk of a BSI. As a scientific community, we have identified numerous isolated BSI risk factors. However, we have not adequately analyzed the integrative, holistic, and cumulative nature of the risk factors, which is essential to determine an individual's specific capacity. In this narrative review, we advocate for a personalized approach to monitor training load so that individuals can optimize their health and performance. We define “cumulative risk profile” as a subjective clinical determination of the number of risk factors with thoughtful consideration of their interaction and propose that athletes have their own cumulative risk profile that influences their capacity to withstand specific training loads. In our narrative review, we outline BSI risk factors, discuss the relationship between BSIs and training load, highlight the importance of individualizing training load, and emphasize the use of a holistic assessment as a training load guide.

Vitamin D history part III: the "modern times"-new questions for orthopaedic practice: deficiency, cell therapy, osteomalacia, fractures, supplementation, infections

PURPOSE

The nutritional basis for rickets was described between 1880 and 1915, at the same period of discovery of other "vital substances" or vitamins. In contrast, rickets could also be prevented or cured by sunshine. But as the capacity to produce vitamin D depends on exposure to ultraviolet B rays (UVB) from sunlight or artificial sources, vitamin D became one of the most frequently used "drugs" in the twentieth century to compensate for insufficient exposure to UVB of humans. Furthermore, as the understanding of vitamin D metabolism grew during the twentieth century, other concerns than rickets occurred for the orthopaedic surgeon: In recent history, deficiency is explored as being an associated factor of different bone pathologies as fracture or prosthetic infection. The aim of this review is to analyze these new data on vitamin D.

MATERIALS AND METHODS

During the twentieth century, there were many concerns for the orthopaedic surgeon: sources and synthesis of vitamin D, regulation of the calcium deposition process for both children and adults, when vitamin D deficiency is observed, and what the best method of vitamin D supplementation is. As target genes regulated by vitamin D are not limited to those involved in mineral homeostasis, orthopedists recently discovered that vitamin D might prevent periprosthetic infection.

RESULTS

The primary source (80%) of vitamin D is dermal synthesis related to the sun. Dietary sources (20%) of vitamin D are fat fishe, beef, liver, and eggs. Vitamin D is produced industrially to be used in fortified foods and supplements. Maintenance of skeletal calcium balance is mediated through vitamin D receptors. Progenitor cells, chondrocytes, osteoblasts, and osteoclasts contain these receptors which explains the role of vitamin D in cell therapy, in the prevention of rickets and osteomalacia. Despite fortified foods, the prevalence of deficiency remains endemic in north latitudes. However, the definition of vitamin D insufficiency or deficiency remains controversial. Vitamin D has been evaluated in patients undergoing fractures and elective orthopaedic procedures Although supplementation may not be able to prevent or cure all the orthopaedic pathologies, oral supplementation is able to improve the vitamin D levels of deficient patients. These vitamin D level improvements might be associated with better functional and clinical outcomes after some surgical procedures and improvement of immunity to decrease the risk of infection in arthroplasties.

CONCLUSION

Vitamin D deficiency is frequent and concerns millions of people in the world. It is therefore normal to find hypovitaminosis in various orthopaedic populations including trauma and arthroplasties. However, we do not know exactly if this phenomenon only reflects the general prevalence of vitamin D deficiency or has an influence on the outcome of some pathologies on specific populations at risk. After the success of treatment of rickets, it is disappointing that we are still wondering in the twenty-first century whether supplementation of a substance synthetized millions of years ago by plankton and necessary for growth of all the animals may improve (or not) clinical and functional outcomes of a simple fracture in humans.

Running ground reaction force complexity at the initial stance phase increased with ageing

Running mechanics could be influenced by some degenerative musculoskeletal changes associated with ageing. However, the shoe effect on ground reaction force (GRF) amplitude and complexity of older runners is still unclear. The objective of our study was to assess the effects of age and shoe on amplitude and complexity of GRF during treadmill running. In total, 20 healthy runners were recruited. GRF data were collected for 13 younger runners and seven older runners during running on an instrumented treadmill at 3.5 m/s. Maximum vertical loading rate and GRF variables were generated. Sample entropy of GRF during the first 20% of the stance phase was calculated to assess GRF complexity. Age and shoe type did not significantly affect the maximal loading rate and GRF. Older participants exhibited higher anteroposterior and vertical GRF sample entropy compared to younger runners. In conclusion, the amplitudes of GRF were not influenced by age group, which indicated that muscle strength in the older runners tested could fulfil mechanical demand (e.g., shock absorption, force generation) during running. However, the increased GRF complexity in initial stance phase with ageing could be a result of reduced muscle contraction coordination and smoothness of force production.

Early diagnosis of femoral neck stress fractures may decrease incidence of bilateral progression and surgical interventions: A case report and literature review

INTRODUCTION

Early intervention in femoral neck stress fractures (FNSFs) can be self- limiting, but they have an insidious presentation. High index of suspicion for an occult fracture is necessary to avoid bilateral progression and/or operative interventions.

CASE PRESENTATION

A 83-year-old female, non-athlete, presents with multiple comorbidities and progressive bilateral FNSFs. Initially the patient presented with groin pain and radiographs demonstrated a non-displaced compression type fracture of the right femoral neck without any inciting events. Subsequently, during a post-operative visit of her right hip, a work-up for new onset contralateral groin pain revealed a non-displaced tension type fracture on the left femoral neck. Both FNSFs were treated with percutaneous cannulated screw fixation.

DISCUSSION

Vitamin D deficiency, poor nutrition, and osteoporosis have been associated with developing stress fractures. This presents an interesting question of whether these frequently referenced risk factors play an interrelated role. Treatment algorithms are controversial, but have been successful in preventing the progression of occult stress fractures. Yet, identification of FNSFs represents a major challenge in diagnosis for clinicians.

CONCLUSION

This case report documents an uncommon fracture pattern in the elderly population. With an aging population, it is pertinent to avoid missed opportunities for prompt diagnosis and implementation of noninvasive methods of treatment. Therefore, paying attention to the risk factors with a high index of suspicion would be ideal.

Stress fractures in older athletes: a case report and literature review

The incidence of stress injuries in older athletes is increasing, associated with a more active older population. The same principles apply for its prevention and treatment, but older athletes usually present a more adverse outcome. It is mandatory to raise awareness to this common, but frequently neglected pathology.

Women with previous stress fractures show reduced bone material strength

Background and purpose - Bone fragility is determined by bone mass, bone architecture, and the material properties of bone. Microindentation has been introduced as a measurement method that reflects bone material properties. The pathogenesis of underlying stress fractures, in particular the role of impaired bone material properties, is still poorly understood. Based on the hypothesis that impaired bone material strength might play a role in the development of stress fractures, we used microindentation in patients with stress fractures and in controls. Patients and methods - We measured bone material strength index (BMSi) by microindentation in 30 women with previous stress fractures and in 30 normal controls. Bone mineral density by DXA and levels of the bone markers C-terminal cross-linking telopeptide of type-1 collagen (CTX) and N-terminal propeptide of type-1 procollagen (P1NP) were also determined. Results - Mean BMSi in stress fracture patients was significantly lower than in the controls (SD 72 (8.7) vs. 77 (7.2); p = 0.02). The fracture subjects also had a significantly lower mean bone mineral density (BMD) than the controls (0.9 (0.02) vs. 1.0 (0.06); p = 0.03). Bone turnover-as reflected in serum levels of the bone marker CTX-was similar in both groups, while P1NP levels were significantly higher in the women with stress fractures (55 μg/L vs. 42 μg/L; p = 0.03). There was no correlation between BMSi and BMD or bone turnover. Interpretation - BMSi was inferior in patients with previous stress fracture, but was unrelated to BMD and bone turnover. The lower values of BMSi in patients with previous stress fracture combined with a lower BMD may contribute to the increased propensity to develop stress fractures in these patients.

EFFECTS OF NORMAL AGING ON LOWER EXTREMITY LOADING AND COORDINATION DURING RUNNING IN MALES AND FEMALES

BACKGROUND

Runners sustain high injury rates. As greater numbers of individuals continue to run past the age of 60, normal physiological changes that occur with aging may further contribute to injuries. Male and female runners demonstrate different mechanics and injury rates. However, whether these mechanics further diverge as runners age and whether or not this potential divergence in mechanics may or may not be associated with a potential for increased injury risk is unknown.

HYPOTHESIS/PURPOSE

The purpose of this study was to compare measures of loading and lower extremity coupling during running with respect to age and sex. It was hypothesized that males and females would demonstrate increasingly diverging mechanics with increased age.

METHODS

Forty-one subjects were placed in four groups: younger males (n=13), younger females (n=6), older males (n=16), and older females (n=6). Ten running trials were collected and analyzed for each subject. Kinematic data were collected and reconstructed using a nine-camera motion analysis system and commercial software. Vertical loading rate (VLR), initial (GRF1) and peak vertical ground reaction force (GRF2) and lower leg joint coupling were calculated for each subject. Analysis was performed using a 2-factor ANOVA (sex X age) to determine differences between groups during the stance phase of running.

RESULTS

Compared to younger subjects, older subjects demonstrated higher GRF1 per body weight (Y: 1.70 (0.19), O: 1.96 (0.23), p < 0.01), higher VLR in body weight/second (Y: 44.17 (6.73), O: 52.76 (8.39), p < 0.01) and lower GRF2 per body weight (Y: 2.47 (0.18), O: 2.35 (0.18), p=0.04). However, no differences existed between males and females or further diverged in the older subjects. There were no differences between or within groups in joint coupling. Finally, no significant differences were seen between sexes and no interactions were found between any variables in the current study.

CONCLUSIONS

Older runners experience greater GRF1 and VLR and lower GRF2. These are factors previously associated with tibial loading and stress fractures. Males and females do not differ on these factors suggesting older female runners may be at no greater risk than younger runners or male runners for lower extremity bony injury based on normal mechanics.

LEVEL OF EVIDENCE

3.

[Pathological and metabolic bone diseases: Clinical importance for fracture treatment]

Pathological and metabolic bone diseases are common and relevant occurrences in orthopedics and trauma surgery; however, fractures are often treated as being the illness itself and not seen as the symptom of an underlying bone disease. This is why further diagnostics and systemic treatment options are often insufficiently considered in the routine treatment of fractures. This review focuses on osteoporosis, osteopetrosis, hypophosphatasia and Paget's disease of bone.In patients with osteoporotic vertebral or proximal femur fractures, pharmaceutical treatment to prevent subsequent fractures is an integral part of fracture therapy together with surgical treatment. Osteopetrosis is caused by compromised osteoclastic bone resorption; therefore, even in the face of an elevated bone mass, vitamin D3 supplementation is crucial to avoid clinically relevant hypocalcemia. Unspecific symptoms of the musculoskeletal system, especially together with stress fractures, are typically found in patients suffering from hypophosphatasia. In these patients measurement of alkaline phosphatase shows reduced enzyme activity. Elevated levels of alkaline phosphatase are found in Paget's disease of bone where bisphosphonates are still the treatment of choice.

Association of Vitamin D With Stress Fractures: A Retrospective Cohort Study

Vitamin D is an essential, fat-soluble nutrient that is a key modulator of bone health. Despite the gaining popularity throughout published medical studies, no consensus has been reached regarding a serum vitamin D level that will guarantee adequate skeletal health in a patient with an increased functional demand. The purpose of the present investigation was to examine the serum concentrations of vitamin D in patients with confirmed stress fractures. A total of 124 patients were included in our retrospective cohort study. Of the 124 patients, 53 had vitamin D levels measured within 3 months of diagnosis. An association was seen in patients with a stress fracture and vitamin D level measured, as 44 (83.02%) of the 53 patients had a serum 25-hydroxyvitamin D level <40 ng/mL. Although an association was seen at our institution in patients with stress fractures and a serum vitamin D concentration <40 ng/mL, a larger and prospective investigation is warranted to further understand the effect of vitamin D level and stress fracture prevention in an active, nonmilitary population.

Intact bone vitality and increased accumulation of nonmineralized bone matrix in biopsy specimens of juvenile osteochondritis dissecans: a histological analysis

BACKGROUND

Although commonly proposed to be the starting point of juvenile osteochondritis dissecans (JOCD), avascular osteonecrosis (AVN) has been an inconsistent finding in histological studies. Analysis of early-stage lesions is required to elucidate the origins of OCD and justify proper treatment.

PURPOSE

To analyze histological sections of JOCD lesions with special emphasis on bone vitality.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Of 64 patients with 74 JOCD lesions (20 females, mean age, 11.4 years; 44 males, mean age, 12.7 years), 34 required surgery because of lesion instability or failed nonoperative treatment. From 9 patients, 11 histological specimens were obtained. Lesions were classified according to the International Cartilage Repair Society (ICRS). Two additional histological control sections were harvested from children without JOCD manifestation. Undecalcified histological sections were histomorphometrically analyzed. To analyze the skeletal health of the patients, biochemical analyses with special emphasis on bone metabolism were performed.

RESULTS

Histologically, no osteonecrosis was visible in any of the cases. Osteocyte distribution was similar among OCD lesions and controls. ICRS OCD I lesions (n = 6) showed no intralesional separation. In ICRS OCD II and III lesions (n = 5), there was a subchondral fracture concomitant with histological characteristics of active repair mechanism (increased bone formation: osteoid volume P = .008, osteoblast number P = .046; resorption: osteoclast number P = .005; and tissue fibrosis compared with controls). Instead, in ICRS OCD I lesions, subchondral osteoid volume (P = .010) and osteoblast number (P = .046) were significantly increased compared with controls; however, no active repair mechanisms (no increased bone resorption or fibrous tissue) were detected, suggesting a focal lack of mineralization. Fifty-seven of 64 patients (89.1%) showed a vitamin D deficiency. The median vitamin D serum level of the patients with ICRS OCD I lesions was 13.6 µg/L.

CONCLUSION

In the present study, osteonecrosis was not found in histological specimens of JOCD. As a secondary finding, focal accumulations of nonmineralized bone matrix indicating a lack of mineralization in ICRS OCD I lesions were revealed. This finding correlated with a low level of vitamin D in the affected children.

Risk factors for tibial stress injuries: a case-control study

OBJECTIVE

To identify physical and behavioral characteristics related to the incidence of tibial stress injuries (TSIs).

DESIGN

Case-control study. No clinical care was conducted.

SETTING

Research laboratories in the San Francisco (the United States) and Gold Coast (Australia) areas.

PARTICIPANTS

Forty-eight patients (21 men and 27 women) with acute TSI, and 36 (16 men and 20 women) age-matched, sex-matched, height-matched, weight-matched, and activity-matched controls with no history of TSI.

INDEPENDENT VARIABLES

Height, weight, body mass index, bone, lean and fat mass, lower limb alignment anomalies, foot type, orthotics, calcium, recent weight change, menstrual history, oral contraceptive use, medications, smoking, alcohol, sleep, training type, and intensity. Differences in continuous variables were tested using 1-way analysis of variance. Categorical variable comparisons were performed with Fisher exact test.

MAIN OUTCOME MEASURE

Tibial stress injury.

RESULTS

Tibial stress injury cases had 2.7% more fat (P < 0.001) and 2.6% less muscle (P < 0.001) as well as lower trochanteric bone mineral content (BMC) (P < 0.001), lumbar spine (LS) area (P < 0.001), femoral neck BMC (P < 0.001), length (P < 0.05), area (P < 0.001), cortical width (P < 0.01), cross-sectional moment of inertia (P < 0.001), and index of bending strength (P < 0.001) than controls. Controls had lower LS BMC (P < 0.01), length (P < 0.001), and broadband ultrasound attenuation (P < 0.001). The use of orthotic insoles was more prevalent in TSI cases than controls (25% vs 5.6%, respectively; P < 0.02), as were foot anomalies (56.3% vs 27.8%, respectively; P = 0.01).

CONCLUSIONS

Tibial stress injury cases had lower lean and higher fat mass, a tendency for smaller bones, and for foot anomalies compared with uninjured matched controls. bone mineral density was normal for both groups.

CLINICAL RELEVANCE

Enhancing lean mass and limiting gains in fat may provide some protection against TSI. Individuals with small skeletal frames are advised to increase training loads particularly gradually and to reduce training intensity at the first sign of pain in the shins.

Stress fracture of the pelvis and lower limbs including atypical femoral fractures-a review

Stress fractures, that is fatigue and insufficiency fractures, of the pelvis and lower limb come in many guises. Most doctors are familiar with typical sacral, tibial or metatarsal stress fractures. However, even common and typical presentations can pose diagnostic difficulties especially early after the onset of clinical symptoms. This article reviews the aetiology and pathophysiology of stress fractures and their reflection in the imaging appearances. The role of varying imaging modalities is laid out and typical findings are demonstrated. Emphasis is given to sometimes less well-appreciated fractures, which might be missed and can have devastating consequences for longer term patient outcomes. In particular, atypical femoral shaft fractures and their relationship to bisphosphonates are discussed. Migrating bone marrow oedema syndrome, transient osteoporosis and spontaneous osteonecrosis are reviewed as manifestations of stress fractures. Radiotherapy-related stress fractures are examined in more detail. An overview of typical sites of stress fractures in the pelvis and lower limbs and their particular clinical relevance concludes this review.

Teaching Points

• Stress fractures indicate bone fatigue or insufficiency or a combination of these.

• Radiographic visibility of stress fractures is delayed by 2 to 3 weeks.

• MRI is the most sensitive and specific modality for stress fractures.

• Stress fractures are often multiple; the underlying cause should be evaluated.

• Infratrochanteric lateral femoral fractures suggest an atypical femoral fracture (AFF); endocrinologist referral is advisable.

The effect of parathyroid hormone and teriparatide on fracture healing

INTRODUCTION

Daily subcutaneous injections of parathyroid hormone (PTH), and its synthetic peptide fragment, teriparatide (PTH 1-34, TPTD), have a net anabolic effect on bone and prevent osteoporotic fractures. TPTD is currently approved for this indication worldwide. Because of the anabolic effect, there is an interest in a role for TPTD (and, where available, human PTH 1-84) in improving bone healing after a fracture. PTH has been studied in animal fracture healing models and in a limited number of human trials. We have reviewed current literature regarding possible mechanisms and efficacy for PTH and TPTD to improve the healing process in the setting of various types of fractures.

AREAS COVERED

Our review focuses first on the role of PTH in normal bone. We then discuss mechanisms of normal bone healing as well as delayed and impaired fracture healing. We summarize pertinent animal data and then review human studies utilizing PTH or TPTD for fracture healing. In particular, we examine unique situations including osteoporotic fractures, diabetes, stress fractures, delayed or poor healing and combination with bisphosphonate therapy.

EXPERT OPINION

Available data indicate there is likely an important role for TPTD and PTH in promoting fracture healing in selected patients, but more clinical trial data are needed.

The pathophysiology, diagnosis, and management of foot stress fractures

INTRODUCTION

There is an increasing prevalence of osteoporosis, and with it a rise in the diagnosis of stress fractures. Postmenopausal women are particularly at risk of stress fractures. This review article describes the pathophysiology of foot stress fractures and the latest diagnostic and treatment strategies for these common injuries.

DISCUSSION

There are numerous risk factors for stress fractures that have been identified in the literature. Reduced bone mineral density is an independent risk factor for delayed union. Prevention of stress fractures with training periodization and nutritional assessment is essential, especially in females. Diagnosis of stress fractures of the foot is based on history and diagnostic imaging, which include radiographs, ultrasound, therapeutic ultrasound, computed tomography, and bone scans; however, magnetic resonance imaging is still the gold standard. Treatment depends on the bone involved and the risk of nonunion, with high-risk fractures requiring immobilization or surgical intervention. Patients presenting with underlying bone mineral deficiency treated without surgery require a longer period of activity modification. Training rehabilitation protocols are described for those with low-risk stress fractures.

RESULTS

A useful algorithm is presented to guide the clinician in the diagnosis and management of such injuries.

Micronutrient Needs of the Elderly

Older adults are becoming a significant percentage of the world's population. A multitude of factors, from the normal aging process to the progression of chronic disease, influence the nutrition needs of this very diverse group of people. Appropriate micronutrient intake is of particular importance but is often suboptimal. Here we review the available data regarding micronutrient needs and the consequences of deficiencies in the ever growing aged population.

A case of bilateral stress fractures in an old woman: three years of pain

In elderly patients frequent episodes of joint pain of lower limbs exacerbated by stress and resistant to treatment occur frequently. This paper reports a case of a long lasting bilateral atraumatic knee pain with a final diagnosis of bilateral stress fractures of proximal tibia in osteoporotic postmenopausal woman. The distinctive trait of this case is that the fracture has set in bilaterally and associated with an isthmic L4-L5 spondylolisthesis in a patient afflicted by a decline in mood. This particular clinical picture has delayed the diagnosis and the suitable treatment for 3 years. Therapy for this type of patients must aim in the acute phase at pain relief and only after must be settled in a long term antiosteoporotic therapy. We choose clodronate acyd for pain relief and after strontium ranelate for osteoporosis prevention.

Medial malleolar insufficiency fracture of the ankle in an elderly patient with osteoporosis

Insufficiency fracture is a type of stress fracture, which is the result of normal stresses on abnormal bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. An early diagnosis is best made with a bone scan or magnetic resonance imaging, as radiographs may initially appear normal. Insufficiency fractures of the lower leg and ankle are less common. Furthermore, reports of medial malleolar insufficiency fracture without any history of trauma in elderly patients are extremely rare. Thus, we report a case with a medial malleolar insufficiency fracture of the ankle in an elderly patient with osteoporosis. This case shows that we should be aware of the possibility of encountering an uncommon medial malleolar insufficiency fracture as a cause of pain in the ankle region of an elderly patient with osteoporosis.

Predictors of 25-hydroxyvitamin D levels in HIV-infected patients in Hawai'i

HIV-infected individuals are at increased risk for several metabolic diseases, including low 25-hydroxyvitamin D [25(OH)D]. Data on the prevalence and risk factors for low 25(OH)D in HIV patients living in the tropics is scarce. Patients ≥ 40 years old on stable antiretroviral therapy were enrolled from March 2009 to July 2011 in Hawai'i (latitude 21° North). Chemiluminescent immunoassay (DiaSorin) was used to determine plasma 25(OH)D levels. Patients were grouped by whether 25(OH)D was collected in summer (May 1 - September 30) or winter (October 1 - April 30). Of 158 patients enrolled, 88 (56%) and 70 (44%) were enrolled in winter and summer, respectively. There were 57.6% Caucasians and 88% men. Over-all median (quartile1, quartile3) age was 51 (46, 57) years and median 25(OH)D was 32.4 (24.0, 41.0) ng/ml. Forty-three percent (n=68) had 25(OH)D<30.0 ng/ml. Median 25(OH)D levels were 29.6 (22.0, 38.0) ng/ml in winter and 36.9 (25.0, 44.5) ng/ml in summer (P = .01). Median body mass index (BMI) of winter patients was significantly higher (P = .03). By simple linear regression, log-transformed 25(OH)D was significantly associated with winter visit (β = -.0737, P = .01), ethnicity (Caucasian versus non-Caucasian, β = .1194, P < .01), BMI (β = -.0111, P < .01) and current use of zidovudine (β = -.1233, P = .03). In multiple linear regression, only Caucasian ethnicity (β = .1004, P < .01) and BMI (β = -.0078, P = .02) retained statistical significance. Seasonal variation in 25(OH)D was observed but the significance of winter visit was not preserved in the final multivariate model. Ethnicity and BMI were better predictors of 25(OH)D levels than season in the tropics.