Imaging Features and Management of Stress, Atypical, and Pathologic Fractures

Reviewing superficial bone lesions: What the radiologist needs to know

Superficial bone lesions arise from the outer components of the bone, from the cortex to the periosteum. Such superficial lesions are often challenges during imaging reporting, and their incorrect interpretation may lead to inadequate management. We present a literature review regarding these lesions according to a standardized division into tumoral and non-tumoral lesions. We also provide a guide for their proper assessment on different imaging modalities. Knowledge of the specific imaging features that aid in the determination of the lesion origin and estimation of the risk of malignancy is fundamental for the radiologist to contribute to adequate patient management.

An emergency medicine review: Multiple myeloma and its complications

INTRODUCTION

Multiple myeloma (MM) and its complications carry a high rate of morbidity and mortality.

OBJECTIVE

This review evaluates MM and its complications, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

MM is the second most common hematologic cancer and associated with monoclonal plasma cell proliferation. The presentation of MM varies, ranging from few symptoms to end organ injury and failure. The most common presenting findings include anemia, bone pain, renal injury, fatigue, hypercalcemia, and weight loss. While clinical outcomes have improved with known therapies, a variety of complications may occur. Anemia is the most common hematologic complication, though hyperviscosity syndrome, bleeding, and coagulopathy may occur. Renal injury is common, and hypercalcemia is the result of bone demineralization. Infection is a major cause of morbidity and mortality. Osteolytic bone disease is a significant feature of MM, present in 70 % of patients, which may result in pathologic and insufficiency fractures. The most serious neurologic complication includes spinal cord compression, and other neurologic complications include peripheral neuropathy and intracranial involvement. Cardiac toxicity may occur with MM therapies, and there is also increased risk of venous thromboembolism. Endocrine complications may also occur, including adrenal insufficiency and thyroid dysfunction.

CONCLUSIONS

An understanding of the complications of MM can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Frequency and clinical implications of findings on true whole-body 18F-FDG PET in the assessment of breast cancer

INTRODUCTION

In the assessment of breast cancer using 18-F FDG PET/CT, the incremental clinical benefit in performing a true whole-body PET/CT (with a field of view (FOV) from the vertex to the toes) over a limited whole-body PET/CT (with a FOV from the base of skull to the mid-thighs) is uncertain.

METHODS

Two hundred and one studies of 120 patients who underwent staging or restaging true whole body 18F-FDG PET/CT for breast cancer were retrospectively identified. Any abnormal hypermetabolic or structural focus outside the limited FOV was recorded and characterised, and referenced with the patient's known disease status and any symptomatology.

RESULTS

A total of 18 (9.0%) studies had FDG avid and/or structural abnormalities detected outside the limited whole-body FOV which were identified as malignant. Seventeen out of 18 (94.4%) were skeletal and of these, 15/17 (88.2%) were located within the lower limbs. In three cases, there were de novo findings but identified in the presence of interval progression of other metastases within the limited whole-body FOV. None of these additional findings is known to have resulted in a change to staging or clinical management.

CONCLUSION

In the assessment of breast cancer, a true whole-body PET/CT can reveal metastases outside the limited whole-body FOV, but these are unlikely to be encountered in isolation and therefore may have little bearing on clinical stage or management. Ultimately, while the choice of FOV should still be based on the individual patient situation, routine utilisation of the true whole-body FOV in the asymptomatic patient may not be necessary.

Prevalence and Characteristics of Pathological Fractures in Patients Referred to Specialist Palliative Care: A Retrospective Study From India

Background: Prevalence of pathological fractures in palliative care is less studied. This study aimed to determine the annual prevalence of pathological fractures and describe the characteristics and treatments in patients with pathological fractures referred to a specialist palliative care clinic in a tertiary care cancer center in India. Methods: Data of adult cancer patients newly referred to the specialist palliative care clinic over 1 year with a clinico-radiological diagnosis of pathological fracture was included. Key outcomes of interest were annual prevalence, clinical characteristics, symptoms and treatments offered. Results: 75 out of 5800 (1.29%) patients newly referred to the clinic over 1 year had pathological fractures. Lung cancer was the most common primary diagnosis (n = 23).Dorsal spine (n = 25) was the most common site of fracture. Pain was the predominant symptom. Mean pain score was 7.04(SD = 1.75) and 42 patients (56%) required strong opioids for analgesia. Only 11 (16%) patients underwent surgical fixation. Median duration from diagnosis of cancer to occurrence of fracture was found to be 329 days. Treatment goals changed to best supportive care in 33 patients (44%) post fracture. Patients with bone and soft tissue neoplasms and those who received only chemotherapy previously had a higher risk of occurrence of fractures. Conclusion: Annual prevalence of pathological fractures in patients referred to the specialist palliative care clinic was 1.29%. It was associated with significant symptom burden and affected oncological treatments. Close monitoring of patients with bone metastases is crucial and proactive implementation of prophylactic measures to prevent such skeletal related events is warranted.

Machine learning models based on CT radiomics features for distinguishing benign and malignant vertebral compression fractures in patients with malignant tumors

BACKGROUND

Radiomics has become an important tool for distinguishing benign and malignant vertebral compression fractures (VCFs). It is more clinically significant to concentrate on patients who have malignant tumors and differentiate between benign and malignant VCFs.

PURPOSE

To explore the value of multiple machine learning (ML) models based on CT radiomics features for differentiating benign and malignant VCFs in patients with malignant tumors.

MATERIAL AND METHODS

This study retrospectively analyzed 78 patients with malignant tumors accompanied by VCFs, 45 patients with benign VCFs, and 33 patients with malignant VCFs. A total of 140 lesions (86 benign lesions, 54 malignant lesions) were ultimately included in this study. All patients were divided into training sets (n = 98) and validation sets (n = 42) according to the 7:3 ratio. The radiomics features were screened and dimensioned, and multiple radiomics ML models were constructed. The receiver operating characteristic (ROC) curve was performed to assess the diagnostic performance.

RESULTS

Five radiomics features were included in the model. All the ML models built have good diagnostic efficiency, among which the support vector machine (SVM) model performs better. The area under the curve (AUC), sensitivity, specificity, and accuracy in the training set were 0.908, 0.816, 0.883, and 0.857, respectively, while those in the validation set were 0.911, 0.647, 0.92, and 0.81, respectively.

CONCLUSION

A variety of ML models built based on CT radiomics features have good value for differentiating benign and malignant VCFs in malignant tumor patients, and the SVM model has a better performance.

Diagnostic Accuracy of Dual-Energy CT for Bone Stress Injury of the Lower Limb

Background Because of its ability to help assess the presence of subtle morphologic changes in bone and bone marrow edema, dual-energy CT (DECT) could be an alternative to MRI in the diagnosis of bone stress injury that includes a stress fracture (SF) and stress reaction (SR). Purpose To determine the diagnostic accuracy of DECT in identifying bone stress injury of the lower limb using MRI as the reference standard. Materials and Methods This prospective study, conducted between June 2021 and January 2024, included consecutive patients clinically suspected of having stress injury (SF or SR) of the lower limb (leg, ankle, or foot). Imaging diagnosis was based on the absence or presence of cortical or periosteal changes, bone marrow edema, or a fracture line. The diagnostic performance of four blinded independent readers was determined for the entire cohort and for the subset of participants without fracture lines. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated. Interobserver agreement was evaluated with Kendall coefficient of concordance (W). Results A total of 184 patients (mean age, 58 years ± 17 [SD]; 97 male) were enrolled. At MRI, 107 of 184 participants (58%) had positive diagnoses, including 70 with SF and 37 with SR. The mean overall sensitivity and specificity were 91% (390 of 428; 95% CI: 0.85, 0.95) and 93% (287 of 308; 95% CI: 0.87, 0.97), respectively, with an AUC of 0.94 (95% CI: 0.91, 0.97). Among patients without fracture lines (n = 114), the mean overall sensitivity and specificity of DECT were 79% (117 of 148; 95% CI: 0.65, 0.88) and 93% (287 of 308; 95% CI: 0.87, 0.97), respectively, with an AUC of 0.87 (95% CI: 0.81, 0.94). The interobserver agreement was very good for diagnosis of SF and SR combined (Kendall W = 0.90) and SR alone (Kendall W = 0.84). Conclusion DECT helped to accurately diagnose bone stress injury of the lower limb by identifying fracture lines and osseous stress reactions. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Breighner in this issue.

Atypical Metatarsal Fractures: Report of Five Clinical Cases

Atypical fractures are well elucidated when they occur in the femur and are related to the use of bisphosphonates. Prolonged therapy with this drug leads to excessive suppression of bone remodeling, which makes the bone more brittle. In general, they are caused by minimal trauma or are atraumatic. This type of fracture is also reported in other bony sites, such as the metatarsus. Some reports and studies on atypical metatarsal fractures have been published, but further investigations are required to better understand this type of fracture and establish the proper diagnosis, treatment and conduct. The present study is a report of five cases of patients who presented metatarsal fractures during therapy with bisphosphonates. All patients were female, had osteoporosis as a preexisting disease, were taking bisphosphonates, presented fractures that were either atraumatic or caused by minimal trauma, and the imaging examination showed a transverse meta-diaphyseal fracture of the fifth metatarsal shaft with thickening of the lateral cortex, image characteristics similar to the criteria used by the American Society for Bone and Mineral Research (ASMBR) to define atypical femur fractures.

Atraumatic Fractures in Multi-Morbid Older Adults: A Series of Five Cases and Review of Literature

Atraumatic fractures (ATFs) are a fragility fracture subtype with occasional medicolegal issues. ATFs are defined as fractures because of a "low-energy mechanism that is usually considered incapable of producing a fracture." They are an underreported disorder, with epidemiological variations. ATF phenomena were previously reported not only in older adults, but also in children, young adults, older adults, and animals. This study is a short retrospective case series exploring atraumatic fractures in a tertiary care university hospital. Over a period of two years, a total of seven ATF cases were identified. However, only five fulfilled the inclusion criteria. Local causes of pathologic fractures (e.g., metastasis) and elder abuse or neglect were excluded. Comparison of the cases' clinical profile, fracture profile, and management was done. All five cases were frail females with significant osteotoxic burdens from medications and multi-morbidities. ATF presentations included typical (as pain) and atypical (as painless, loud crack, and sudden giveaway) symptomatology. One ATF had a coincident unexplained aseptic fever. Three cases had more than one fracture (fracture cascade), confirmed and followed up by x-rays. All the cases were managed conservatively except for one case that underwent hip hemiarthroplasty. Plans of care included managing the osteotoxic multi-morbidities burden, focusing on the whole body, not only on the fracture or bone. The study provided insights about challenges in presentations of ATF (as the bone fracture acute phase reaction: osteogenic aseptic fever). Risk factors are classically assumed to be osteoporosis, but it is usually systemic and multifactorial. A high risk of fracture warning sign could help decrease ATF occurrence or fracture cascades. Four ATF categories were detected to help healthcare systems identify high-risk patients and raise awareness among medical staff, families, and caregivers. Future studies of the at-risk groups are needed to understand ATF knowledge gaps, challenges, and the best treatments.

[Stress injuries of bone in children and adolescents]

Stress injuries of bone in childhood and adolescence are the result of an imbalance between physical stress on the growing musculoskeletal system and its intrinsic resilience. Children who are very active in sports are particularly affected. The classical stress injuries mainly occur in the area of the lower leg, the metatarsus and the lower lumbar spine due to the disproportionate load on healthy bone; however, overuse syndromes can also occur in the area of the growth plates and possibly lead to growth plate disorders. The anamnesis usually shows stress-related pain that has existed for a long time without trauma. As part of the differential diagnosis, a stress injury must first be included in the considerations due to it being a rare entity. An X‑ray examination can show the first signs of a stress reaction. In the event of a conspicuous periosteal reaction, a malignant event must also be considered. As a rule, the MRI examination is then groundbreaking and in some rare cases biopsies have to be considered. The treatment of stress injuries is usually conservative. Recurrences should be counteracted by exercise control.

[Contemporary imaging examinations for (suspected) stress fractures]

Stress fractures belong to the group of atraumatic fractures. A low-impact and repetitive load is the underlying cause and no fracture would occur under physiological circumstances. The conventional X‑ray examination remains the initial imaging modality when a stress fracture is suspected. In contrast, magnetic resonance imaging (MRI) is the gold standard and is also used to rule out other pathological changes. Computed tomography (CT) should be included if the MRI findings are unclear. New techniques, such as dual energy computed tomography (DECT) and magnetic resonance bone imaging (MR bone) should be used more frequently in practice in the future and become increasingly more important for the correct diagnosis.

Weight-Bearing CT with Maximum Ankle Dorsiflexion to Identify Impingement and Tibial Plafond Stress Fracture: A Case Report

CASE

A 25-year-old male pole vaulter presented with several months of right ankle pain. Radiographs showed an anterior tibial osteophyte with a small intra-articular body suggesting impingement. Weight-bearing computed tomography (CT) revealed an associated tibial plafond stress fracture. Subsequent arthroscopy with osteophyte resection and loose body removal significantly improved symptoms, and he gradually resumed training.

CONCLUSION

Stress fractures should always be considered in athletes with ankle pain. A unique aspect of this case was the use of weight-bearing CT in diagnosis and surgical planning. To our knowledge, this is the first described case in which weight-bearing CT was used in this fashion.

Suggestion of a Novel Classification Based on the Anatomical Region and Type of Bilateral Fatigue Femoral Fractures

Purpose: Bilateral fatigue femoral fractures (BFFF) represent an extremely rare clinical entity. The present study introduces a novel classification, in order to categorize the BFFFs and provide a thorough review of all these, so far in the literature, reported cases. Methods: The BFFF were classified taking into account the anatomical region of the femoral fracture; (fh): femoral head, (sc): sub-capital, (pt): peri-trochanteric, (st): sub-trochanteric, (s): shaft, (d): distal femur and the fracture type (complete or incomplete); type I: bilateral incomplete fractures, type II: unilateral incomplete fracture, and type III: bilateral complete fractures. Type III was further subdivided into type IIIA: bilateral non-displaced fractures, type IIIB: unilateral displaced fracture, and type IIIC: bilateral displaced fractures. Furthermore, a meticulous review of the PubMed and MEDLINE databases was conducted to locate all articles reporting these injuries. Results: A total of 38 patients (86.8% males), with a mean age of 25.3 years, suffering BFFFs were identified from the literature search. The mean time interval from symptoms' onset to diagnosis was 54 days. According to the proposed classification, 2.6% of the fractures were categorized as type I (h), 36.8% as type I (sc), 2.6% as type I(st/s), 7.9% as type I (s), 2.6% as type I (d), 5.4% as type II (fh), 26.3% as type II (sc), 2.6% as type IIIA (st), 2.6% as type IIIA (d), 5.4% as type IIIB (sc), 2.6% as type IIIB (d) and 2.6% as type IIIC (sc). Surgery was performed in 52.6%, while non-operative treatment was followed in 47.4% of the population. Regarding the fracture type, 75% of type I fractures were conservatively treated, while 91.7% and 66.6% of type II and III fractures were surgically treated. For patients treated conservatively, the mean time from diagnosis to return to previous status was 260 days, while for patients treated surgically, 343 days. Conclusions: BFFFs, although rare, may pose a diagnostic and therapeutic challenge. The present classification offers valuable information and may act as a guide for the management of these patients.

Position Statement: Atypical Femoral Fracture from the Korean Society for Bone and Mineral Research in 2023

As the aging population increases, the number of patients with osteoporosis is gradually rising. Osteoporosis is a metabolic bone disease characterized by low bone mass and the microarchitectural deterioration of bone tissue, resulting in reduced bone strength and an increased risk of low-energy or fragility fractures. Thus, the use of anti-resorptive agents, such as bisphosphonates (BPs), to prevent osteoporotic fractures is growing annually. BPs are effective in reducing hip and other fractures. However, the longer a patient takes BPs, the higher the risk of an atypical femoral fracture (AFF). The exact mechanism by which long-term BP use affects the development of AFFs has not yet been clarified. However, several theories have been suggested to explain the pathogenesis of AFFs, such as suppressed bone remodeling, impaired bone healing, altered bone quality, and femoral morphology. The management of AFFs requires both medical and surgical approaches. BPs therapy should be discontinued immediately, and calcium and vitamin D levels should be evaluated and supplemented if insufficient. Teriparatide can be used for AFFs. Intramedullary nailing is the primary treatment for complete AFFs, and prophylactic femoral nailing is recommended if signs of an impending fracture are detected.

Clinical Characterization of Oral and Maxillofacial Tumors and Tumor-Like Lesions in Children and Adolescents

PURPOSE

To investigate the clinical characteristics of oral and maxillofacial tumors in children and adolescents.

METHODS

This is a retrospective study of patients who had oral and maxillofacial tumors under the age of 18 years and were treated at the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from January 1990 to July 2021 (31 y). Their general conditions, pathological diagnosis, gender, age, and anatomical location were counted to analyze their morbidity and composition characteristics.

RESULTS

This study contained 5405 cases, including 2903 male patients and 2502 female patients, with a median age of 9 years. Peak incidence was observed in the 14 to 18 years age group. The mandible (22.15%), maxilla (11.75%), and tongue (9.25%) were the most common sites of incidence. Malignant and intermediate type tumors accounted for 13.04%, benign tumors and tumor-like lesions for 55.67%, most often occurs in the maxillofacial bone, of which fibro-osseous lesions constitute an important part. Cysts accounted for 31.29%. Among the tumors occurring in the jaws, the most common malignant type was sarcoma, and ameloblastoma was the most common benign tumor. Malignant jaw tumors were mostly treated by resection, 10.64% by fibular flap reconstruction. While benign jaw tumors and tumor-like lesions were mostly treated by resection or curettage.

CONCLUSIONS

The distribution of anatomical location and pathological types of oral and maxillofacial tumors in children has certain characteristics, so that the selection of their treatment options is different from that of adults due to the consideration of the growth and developmental characteristics of children.

Bone Stress Injuries at the Ankle and Foot

Bone stress injuries (BSIs) are a frequent finding in athletes, particularly of the foot and ankle. A BSI is caused by recurring microtrauma to the cortical or trabecular bone exceeding the repair capacity of normal bone. The most frequent fractures at the ankle are low risk, characterized by a low risk for nonunion. These include the posteromedial tibia, the calcaneus, and the metatarsal diaphysis. High-risk stress fractures have a higher risk for nonunion and need more aggressive treatment. Examples are the medial malleolus, navicular bone, and the base of the second and fifth metatarsal bone.Imaging features depend on the primary involvement of cortical versus trabecular bone. Conventional radiographs may remain normal up to 2 to 3 weeks. For cortical bone, early signs of BSIs are a periosteal reaction or the "gray cortex sign," followed by cortical thickening and fracture line depiction. In trabecular bone, a sclerotic dense line may be seen. Magnetic resonance imaging enables early detection of BSIs and can differentiate between a stress reaction and a fracture. We review typical anamnestic/clinical findings, epidemiology and risk factors, imaging characteristics, and findings at typical locations of BSIs at the foot and ankle that may help guide treatment strategy and patient recovery.

Atraumatic Isolated Bilateral Fibular Shaft Fragility Fracture: A Rare Case

Fragility fractures, a form of stress fracture brought on by physiological stress on weak bones, are not common. It might be challenging to diagnose a fragility fracture since a standard radiograph shows signs of fracture repair rather than the actual fracture. We present a case of a 32-year-old woman who has been complaining of both leg pain for the last 4 months and has been unable to stand for the last 1 week. Further analysis revealed that her vitamin D levels were insufficient.

Pathological fracture due to primary bone lymphoma in a patient with a history of prostate cancer: A case report and review of literature

Primary bone lymphoma (PBL) is a rare extranodal presentation within lymphomas and primary bone malignancies. Pathologic fracture (PF) is a common complication of metastatic bone disease but is, rarely, the presentation of a primary bone tumor. We report a case of an 83-year-old man with a history of untreated prostate cancer, presenting with atraumatic fracture of his left femur after months of intermittent pains and weight loss. Radiographic workup revealed a lytic lesion suspicious for PF secondary to metastatic prostate cancer; however, initial core biopsy results were inconclusive for malignancy. A complete blood count with differential and complete metabolic panel was within normal limits. During surgical fixation and nailing of the femur, a reaming biopsy was performed as a repeat measure and revealed diffuse large B-cell lymphoma. Staging with positron emission tomography and computed tomography found no evidence of lymphatic or visceral involvement and chemotherapy was promptly initiated. This case highlights the diagnostic workup challenges for PF secondary to PBL, especially in the setting of concurrent malignancy. Because of the non-specific presentation of a lytic lesion on imaging associated with atraumatic fracture, we highlight PBL as an important diagnostic consideration.

Imaging of bone marrow pitfalls with emphasis on MRI

Normal marrow contains both hematopoietic/red and fatty/yellow marrow with a predictable pattern of conversion and skeletal distribution on MRI. Many variations in normal bone marrow signal and appearances are apparent and the reporting radiologist must differentiate these from other non-neoplastic, benign or neoplastic processes. The advent of chemical shift imaging has helped in characterising and differentiating more focal heterogeneous areas of red marrow from marrow infiltration. This review aims to cover the MRI appearances of normal marrow, its evolution with age, marrow reconversion, variations of normal marrow signal, causes of oedema-like marrow signal, and some common non-neoplastic entities, which may mimic marrow neoplasms.

Imaging of common hip pathologies in runners

Running is an increasingly popular sport and form of exercise. Because of the importance of the hip in the biomechanics involved with running, forming the primary connection between the axial and appendicular skeleton of the lower extremities, accurate diagnosis and reporting of hip pathology are vital for appropriate management. This review provides an overview of the most common hip pathologies and injuries encountered in runners. Radiologic studies, primarily conventional radiography and magnetic resonance imaging (MRI) provide useful diagnostic information and should be used in combination with clinical findings to help guide therapeutic management.

Fracture through Pre-Existing Tarsal Coalition: A Narrative Review

Tarsal coalitions are abnormal fibrous or bony connections between the tarsal bones of the foot. While not always symptomatic, coalitions can cause pain, alterations in forefoot and hindfoot morphology, and alterations in foot and ankle biomechanics. Previous research has described the association of tarsal coalitions with fractures of the lower extremity. Multiple reports of acute fracture in the presence of tarsal coalition have been presented, as have reports of stress fractures of the foot and ankle with concomitant coalition, insidious in onset and thought to be related to aberrancies in foot and ankle biomechanics. The purpose of this review is to discuss the biomechanics seen in tarsal coalitions and to describe reports of fracture occurring concomitantly with tarsal coalitions. We will discuss diagnostic options and treatment approaches in the setting of fracture with preexisting tarsal coalition.

Isolated bilateral fibular insufficiency fractures: Case report of an unusual entity

Insufficiency fractures are a type of stress fractures that occur due to physiological stress on weakened bones. These have certain sites of predilection of which an uncommon site is fibular shaft. Isolated bilateral fibular fractures have previously only been reported twice, where the causes were repeated trauma and fatigue fracture. Insufficiency fractures of both fibula in isolation have not previously been reported. We present this case where a young patient presented with these fractures and was found to have vitamin D deficiency on subsequent investigations.

Additional Imaging is of Limited Value in Traumatic Hip Fractures With a History of Distant Malignancy and No Suspicious Lesion on Plain Radiographs

OBJECTIVE

To determine the value of obtaining additional preoperative imaging in patients with a traumatic hip fracture and a history of malignancy in whom plain radiographs show no lesion suspicious for metastases.

DESIGN

Retrospective review.

SETTING

Teaching NHS Trust in the United Kingdom, over an 8-year period treating 4421 hip fractures.

PATIENTS/PARTICIPANTS

Three hundred sixty-seven patients with hip fracture and a history of malignancy at a site distant to the hip. Three hundred thirty patients had a history of trauma and no lesion on the plain radiograph suspicious for metastases.

MAIN OUTCOMES MEASUREMENTS

Whether obtaining additional imaging preoperatively (MRI, CT, and bone scan) identified metastases or affected management.

RESULTS

32/330 patients had further preoperative imaging, none of which demonstrated a pathological fracture secondary to malignancy. On follow-up, 3/330 (0.9%) cases were found to have occult metastasis at the hip fracture site. All 3 had only plain radiographs before surgery. In 2, this was identified on histological examination of intraoperative samples, and in 1, radiologically as a metastatic metaphyseal lesion 18 months after a hemiarthroplasty. Only in the latter case, preoperative identification of hip metastasis could have altered surgical management. Patients undergoing further preoperative imaging waited significantly longer for surgery (35 ± 26 vs. 51 ± 26 hours, P = 0.0011).

CONCLUSIONS

In the absence of a suspicious metastatic lesion on initial plain radiographs, further preoperative imaging is unlikely to identify a lesion that will affect management and confers significant delays to surgery. Sending intraoperative histological samples may help guide postoperative oncological management, but further work is needed to prove its utility.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Fracture through tracking pin sites following a robotic-assisted total knee arthroplasty

The use of computer-navigated, robotic-assisted total knee arthroplasty (TKA) is expanding as the result of widespread efforts to improve the precision of implant placement and to restore mechanical, anatomic, and kinematic alignment. The procedure requires placement of femoral and tibial pins to mount the robotic tracking system. Fractures through tracking pin sites following robotic-assisted TKA are rare; only 30 cases have been reported to our knowledge. It is probable that this complication will become more frequent as the use of robotic-assisted TKAs continues to grow. We report the case of a 67-year-old female who suffered a fracture of the femur through two pin sites 3 months after a robotic-assisted TKA. We believe that this report is the first case in the radiologic literature. Our case demonstrates some of the difficulties of recognizing this complication and raises questions about appropriate post-operative imaging.

Total knee arthroplasty with long tibial stem for tibial stress fractures with knee osteoarthritis: Two birds with one stone

PURPOSE

The treatment and outcome of tibial stress fractures concomitant with knee osteoarthritis (OA) are complicated. The aim of this study was to evaluate the functional and radiological outcome of total knee arthroplasty with long tibial stem as a treatment for patients having knee OA and tibial stress fracture.

METHODS

Patients who were diagnosed to have proximal tibia stress fracture along with knee OA at our institution between June 2013 and November 2018 were included in our study. All patients underwent total knee arthroplasty with long tibial stem. Preoperative and postoperative functional assessments were done according to range of movement of the knee joint, knee society score and knee injury and OA outcome score. Descriptive analysis was carried out by mean and standard deviation for quantitative variables, frequency and proportion for categorical variables.

RESULTS

Twelve patients were included in the study. All patients were found to have stress fractures in the proximal half of tibia and extra-arthrosis. Four patients had non-union/delayed union, and 8 patients had acute fractures. The average preoperative range of movement was 88.1°, which improved to 116.3° at 3 months following surgery. It was found that the fracture has healed in all cases. Mean knee society score improved from 32.9 preoperatively to 89.3 at 1 year follow-up. Knee injury and OA outcome score improved from a mean score of 28.3 preoperatively to 81.1 at 1 year follow-up.

CONCLUSION

Stress fractures can occur in the proximal tibia in patients with knee OA. Total knee arthroplasty with tibial stem provides a suitable solution for both conditions. Additional plating or bone graft is unlikely to be required.

Femoral Neck Stress Fracture of a Male, Healthy Marathon Runner - Case Report and Literature Review

In the present report, a case of a healthy, 38-year-old male recreational marathon runner who presented in the emergency department is discussed. He was diagnosed with a stress fracture of the femoral neck and treated surgically using a dynamic hip screw (DHS). One year after surgery, the patient was able to return to most of his previous sports activities. In the present report, the existing literature on the subject is exhibited and the points of interest in terms of incidence, risk factors, diagnosis, classification, treatment, and long-term outcome are analyzed. We suggest operative treatment of stress fractures of the femoral neck even in cases of complete undisplaced ones. This way, the risk of a displacement is counteracted, and patients can quickly return to daily activities without having to withstand long-term immobilization.

Beyond the Hip Labrum: A Pictorial Review

Magnetic resonance arthrography and 3T magnetic resonance imaging of the hip are a technique commonly performed in young, physically active patients presenting with pain relating to the hip, with the focus on assessing for the presence of labral tears and femoroacetabular impingement. Abnormal signal within the labrum can be misleading, however, as labral tears are a frequent incidental finding and have been identified in a large proportion of the asymptomatic population. A range of extralabral conditions can cause hip-related pain in young patients, including pathology related to the bones, joints, and periarticular soft tissues. It is vital that the radiologist is aware for these pathologies and examines for them even in the presence of a confirmed labral tear. In this article, we review a range of common extralabral pathologies responsible for hip pain and highlight review areas that aid in their diagnosis.

Lower-extremity fatigue fracture detection and grading based on deep learning models of radiographs

OBJECTIVES

To identify the feasibility of deep learning-based diagnostic models for detecting and assessing lower-extremity fatigue fracture severity on plain radiographs.

METHODS

This retrospective study enrolled 1151 X-ray images (tibiofibula/foot: 682/469) of fatigue fractures and 2842 X-ray images (tibiofibula/foot: 2000/842) without abnormal presentations from two clinical centers. After labeling the lesions, images in a center (tibiofibula/foot: 2539/1180) were allocated at 7:1:2 for model construction, and the remaining images from another center (tibiofibula/foot: 143/131) for external validation. A ResNet-50 and a triplet branch network were adopted to construct diagnostic models for detecting and grading. The performances of detection models were evaluated with sensitivity, specificity, and area under the receiver operating characteristic curve (AUC), while grading models were evaluated with accuracy by confusion matrix. Visual estimations by radiologists were performed for comparisons with models.

RESULTS

For the detection model on tibiofibula, a sensitivity of 95.4%/85.5%, a specificity of 80.1%/77.0%, and an AUC of 0.965/0.877 were achieved in the internal testing/external validation set. The detection model on foot reached a sensitivity of 96.4%/90.8%, a specificity of 76.0%/66.7%, and an AUC of 0.947/0.911. The detection models showed superior performance to the junior radiologist, comparable to the intermediate or senior radiologist. The overall accuracy of the diagnostic model was 78.5%/62.9% for tibiofibula and 74.7%/61.1% for foot in the internal testing/external validation set.

CONCLUSIONS

The deep learning-based models could be applied to the radiological diagnosis of plain radiographs for assisting in the detection and grading of fatigue fractures on tibiofibula and foot.

KEY POINTS

• Fatigue fractures on radiographs are relatively difficult to detect, and apt to be misdiagnosed. • Detection and grading models based on deep learning were constructed on a large cohort of radiographs with lower-extremity fatigue fractures. • The detection model with high sensitivity would help to reduce the misdiagnosis of lower-extremity fatigue fractures.

Metastasis of submandibular Adenoid cystic carcinoma to the femur bone causing pathological fracture: A case report

Introduction: Adenoid cystic carcinoma (ACC) is a rare head and neck malignancy and is likely to be diagnosed in the major salivary glands. It's also known for its slow clinical course and prolonged survival unless no distant metastasis occurs. Even after a long period from the detection of the primary tumor, metastasis to the lung, brain, liver, and bone has a tendency to occur. Case presentation: We report a 53-year-old man who presented with a pathological femur fracture thirteen years after the presentation of submandibular ACC. Our patient reported an improved patient-reported outcome after undergoing resection hemiarthroplasty for his bone metastasis. Conclusion: We tried to accentuate the importance of periodical visits for the probability of distant metastasis and the work-up if it's necessary in such a rare case. It should be kept in mind that proper management of bone metastasis may lead to improvements in the quality of life.

Lumbar Pedicular Stress Fracture Post-laminectomy: a Case Report

We present the case of a 74-year-old male suffering from degenerative lumbar spinal stenosis with neurogenic claudication resulting in reduced walking distance. MR imaging indicated spinal canal stenosis at the level of L3–L4 and L4–L5 due to degenerative discopathy, discal extrusion, and facet arthrosis. After conservative treatment had failed, a multilevel laminectomy was performed. Four months postoperatively, the patient developed a stress fracture of the L4 pedicle. Pedicular stress fractures are uncommon and few case reports are found in the literature. Usually, they occur due to contralateral spondylolysis or congenital anomalies. The findings in this case however suggest a change of biomechanical load over the pedicle due to spinal surgery. An overview of the literature concerning spinal instability after laminectomy is provided. Spinal decompressive surgery can significantly change the biomechanical forces on the spinal structures, resulting in important postoperative complications. Whether pedicle stress fracture in this case is a result of pre- or postoperative circumstances remains a subject for discussion.

Educational Case: Osteoid Osteoma

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

Report of Missed Non-Hodgkin's Lymphoma Presenting as Pathological Tibial Fracture

Pathological fractures usually occur in patients with known malignancies, though pathological fracture may be the first sign of cancer. Malignant pathological fractures most commonly represent metastatic lung, breast, kidney, thyroid, or prostate cancer and typically occur in the spine, pelvis, femur, and humerus. We present the case of a 71-year-old female with an atraumatic tibial fracture in which further imaging was not pursued. Five months later, she was diagnosed with non-Hodgkin’s lymphoma. Pathological proximal tibial fracture is an exceedingly rare presentation of lymphoma; however, diagnostic delay could likely have been avoided if a thorough workup had been pursued. Our case highlights the importance of careful examination of all patients presenting with a low-energy fracture, particularly when constitutional symptoms suggestive of cancer are present. All patients with pathological fractures should receive a thorough physical examination that includes lymph node palpation. 

Progression of atypical femur stress fracture after discontinuation of bisphosphonate therapy

Atypical femur fracture (AFF) is an uncommon complication of long-term bisphosphonate use, but the risk declines substantially after treatment cessation. We report a case of a 70-year-old woman with osteopenia treated with alendronate for 9 years who presented with right mid-thigh pain and radiographic findings of focal lateral cortical thickening in the right mid-femur and lateral cortex irregularity in the proximal-mid left femur. Alendronate was discontinued, but she remained on estrogen for menopausal symptoms. Four years later, a horizontal linear translucent defect was seen in the right mid-femur area of cortical hypertrophy, consistent with an incomplete AFF. The patient underwent prophylactic intramedullary rodding of the right femur and estrogen was discontinued. Three years later (7 years after initial presentation), the cortical irregularities in the left femur were more prominent and three small horizontal linear translucent defects were now evident, consistent with early incomplete atypical fracture development. The patient also suffered a wrist fracture. She was treated with teriparatide for 1.5 years with resolution of the translucent defects in the left but not the right femur, although abnormal thickening of the lateral cortex persisted in both femurs. Our case demonstrates incomplete atypical femur fracture progression in a patient with long-term bisphosphonate exposure, even after treatment cessation. These findings highlight the importance of follow-up for patients who develop diaphyseal femur stress fractures and the potential for early healing with anabolic therapy. This case also demonstrates the challenge in managing older patients with incomplete AFF at risk for progression to complete AFF and osteoporotic fracture.

Stress Imaging of Bone

This article defines stress injury, including insufficiency and fatigue fractures. The pathophysiology and risk factors for development of stress injuries are also discussed. The most common locations, including specific imaging examples, are reviewed with an emphasis on early detection and differentiation of high-risk and low-risk locations. Optimal imaging modalities with associated imaging findings are covered, as well as some potential pitfalls to avoid. The importance of correlating imaging findings with symptoms and the prognostic value of imaging grading are also discussed.

Avascular necrosis of the first metatarsal head in a young female adult: A case report and review of literature

BACKGROUND

This case study describes an atypical presentation of avascular necrosis (AVN) of the first metatarsal head, which is largely unfounded in the literature.

CASE SUMMARY

A healthy 24-year-old female initially presented with pain at the first metatarsophalangeal joint (MTPJ) and was diagnosed with AVN by physical examination and magnetic resonance imaging. The patient demonstrated atypically poor progress in recovery, despite being in otherwise good health and being of young age, with no history of corticosteroid or alcohol use. The patient also did not have any history or clinical features of autoimmune disease or vasculitis, such as systemic lupus erythematosus. The patient was managed with conservative treatment for 18 mo, which allowed for gradual return of full range of motion of the first MTPJ and subsiding pain, permitting the patient to return to high-intensity sports training and full weight-bearing. Throughout her recovery, many differential diagnoses were ruled out through specific investigations leading to further reinforcement of the diagnosis of AVN of the 1^st metatarsal head.

CONCLUSION

Atypical AVN may occur with no predisposing risk factors. Treatment is mainly conservative, with unclear guidelines in literature on management.

[Radiological aspects in the diagnostics of pathological fractures]

Radiological diagnostics play a key role in the identification and assessment of pathological fractures. Conventional projection radiography is still the mainstay of imaging investigations. With knowledge of the patient history, the morphology and location of a fracture as well as concomitant findings, such as osteolysis or periosteal reactions can add valuable information on the origin of the fracture. Magnetic resonance imaging (MRI) is the imaging modality of choice for the local diagnostic work-up as it provides insights into the medullary cavity and visualizes potential extraosseous tumor tissue in the fracture zone. Computed tomography (CT) imaging provides valuable information on the morphological features of fractures and is useful for the planning of the surgical approach. Furthermore, it is the modality of choice for whole-body staging. In most cases of pathological fractures without a history of malignancy, a biopsy and histological work-up is recommended.

Pathological fracture in paediatric bone tumours and tumour-like lesions: A predictor of benign lesions?

OBJECTIVE

To determine the incidence and causes of pathological fractures in paediatric bone tumours and tumour-like lesions, and to determine if they are predictive of benign lesions.

METHODS AND MATERIALS

Retrospective review of children with suspected bone tumours referred to a specialist musculoskeletal oncology service between September 2019 and August 2020. Data recorded included patient age and gender, lesion location, the presence of a pathological fracture on the initial plain radiograph, and the final diagnosis made either by image-guided biopsy/curettage or based on typical imaging features.

RESULTS

231 patients were included with 233 lesions (138 males and 93 females with mean age 10.5 years, range 3 months-18 years). Final diagnosis was based on histology in 85 (36.5%) cases and imaging in 148 (63.5%) cases, 52 (22.3%) lesions classed as non-neoplastic, 139 (59.7%) as benign and 42 (18%) as malignant. Pathological fractures were seen in 41 cases (17.6%) at presentation, involving the humerus in 19 (46.3%), the femur in 14 (34.1%), the tibia in 3 (7.3%), the fibula and radius in two each (4.9%) and the second toe proximal phalanx in 1 (2.4%) (p < 0.001). The commonest underlying lesions included simple bone cyst (n = 17; 41.5%) and non-ossifying fibroma (n = 10; 24.4%). Only 4 cases (9.75%) were malignant, one case each of osteosarcoma, Ewing sarcoma, leukaemia and BCOR undifferentiated round cell sarcoma. Pathological fracture occurred in 27.7% of non-malignant lesions and 9.5% of malignant lesions, this difference being statistically significant (p < 0.001).

CONCLUSION

Pathological fractures were seen in 17.6% of paediatric bone tumours, tumour-like lesions, being significantly associated with humeral location and non-malignant diagnosis.

ADVANCES IN KNOWLEDGE

Demonstrates the frequency, location and underlying diagnosis of pathological fractures in paediatric bone tumour and tumour-like lesions.

Bilateral Tibial Stress Fractures and Osteoporosis in a Young Patient

Stress fractures result from microscopic bone injury due to repetitive submaximal stress and include fatigue and insufficiency fracture components. Fatigue fractures generally occur in runners and athletes and are caused by abnormal physical load on the bone. On the other hand, insufficiency fractures are generally seen in the elderly secondary to osteoporosis, typically involving the pelvis and surrounding bones. Insufficiency fracture occurs as a result of normal loading in the abnormal bone. In this case report, we describe a young patient with bilateral tibial stress fractures with both fatigue and insufficiency components.

Atraumatic fractures of the femur

Atraumatic fractures of femur, although not as common as traumatic fractures, are frequently encountered in the clinical practice. They present with non-specific symptoms and can be occult on initial imaging making their diagnosis difficult, sometimes resulting in complications. Overlapping terminologies used to describe these fractures may hamper effective communication between the radiologist and the clinician. In this article, we review various atraumatic fractures of femur, terminologies used to describe them, their imaging findings and differential diagnosis. The article also describes the aetiology, pathophysiology and relevant biomechanics behind these fractures. An approach to atraumatic femoral fractures has been outlined.

Combined radiomics-clinical model to predict malignancy of vertebral compression fractures on CT

OBJECTIVES

To develop and validate a combined radiomics-clinical model to predict malignancy of vertebral compression fractures on CT.

METHODS

One hundred sixty-five patients with vertebral compression fractures were allocated to training (n = 110 [62 acute benign and 48 malignant fractures]) and validation (n = 55 [30 acute benign and 25 malignant fractures]) cohorts. Radiomics features (n = 144) were extracted from non-contrast-enhanced CT images. Radiomics score was constructed by applying least absolute shrinkage and selection operator regression to reproducible features. A combined radiomics-clinical model was constructed by integrating significant clinical parameters with radiomics score using multivariate logistic regression analysis. Model performance was quantified in terms of discrimination and calibration. The model was internally validated on the independent data set.

RESULTS

The combined radiomics-clinical model, composed of two significant clinical predictors (age and history of malignancy) and the radiomics score, showed good calibration (Hosmer-Lemeshow test, p > 0.05) and discrimination in both training (AUC, 0.970) and validation (AUC, 0.948) cohorts. Discrimination performance of the combined model was higher than that of either the radiomics score (AUC, 0.941 in training cohort and 0.852 in validation cohort) or the clinical predictor model (AUC, 0.924 in training cohort and 0.849 in validation cohort). The model stratified patients into groups with low and high risk of malignant fracture with an accuracy of 98.2% in the training cohort and 90.9% in the validation cohort.

CONCLUSIONS

The combined radiomics-clinical model integrating clinical parameters with radiomics score could predict malignancy in vertebral compression fractures on CT with high discriminatory ability.

KEY POINTS

• A combined radiomics-clinical model was constructed to predict malignancy of vertebral compression fractures on CT by combining clinical parameters and radiomics features. • The model showed good calibration and discrimination in both training and validation cohorts. • The model showed high accuracy in the stratification of patients into groups with low and high risk of malignant vertebral compression fractures.

Actual applications of magnetic resonance imaging in dentomaxillofacial region

Magnetic resonance imaging (MRI) is a versatile imaging modality utilized in various medical fields. Specifically used for evaluation of soft tissues, with non-ionizing radiation and multiplanar sections that has provided great guidance to diagnosis. Nowadays, use of MRI in dental practice is becoming more pervasive, especially for the evaluation of head-and-neck cancer, detection of salivary gland lesions, lymphadenopathy, and temporomandibular joint disorders. Understanding the basic principles, its recent advances, and multiple applications in dentomaxillofacial region helps significantly in the diagnostic decision making. In this article, the principle of MRI and its recent advances are reviewed, with further discussion on the appearance of various maxillofacial pathosis.

Grade 4 Distal Femur Stress Fracture in a Long-Distance Hiker on the Appalachian Trail

Although stress injuries are a common occurrence in sports medicine clinics, a distal femur stress fracture is less so. Early detection can result in a favorable prognosis and may prevent the need for surgical intervention. A misdiagnosis resulting in delay of care can result in significant complications. This case report documents a rare distal femur stress fracture in a long-distance hiker. A 35-y-old male presented to an orthopedic clinic in Pennsylvania with left knee pain after completing 1423 km (884 mi) of the Appalachian trail over a 4-mo period. He was attempting a thru-hike, a specialized type of backpacking focused on completing a trail from end-to-end. Thru-hiking of this trail involves backpacking between Georgia and Maine, covering about 3540 km (2200 mi) with approximately 141,580 m (464,500 ft) of gain/loss in elevation. His pain began 2 mo into his hike when he noted medial sided left knee discomfort. Over the following 2 mo he sought treatment at 2 different locations along the trail with etiology undetermined. Upon evaluation in Pennsylvania, history and physical exam were suggestive of a stress fracture. Radiologic studies confirmed a closed nondisplaced nonangulated grade 4 transverse fracture of the shaft of the distal left femur. The patient was instructed to terminate his hike immediately and he was placed on nonweight bearing status. This case illustrates the importance of considering a distal femur stress fracture for the differential diagnosis of persistent knee pain in a long-distance hiker.

Risk of complete atypical femur fracture with Oral bisphosphonate exposure beyond three years

Background

Bisphosphonate (BP) therapy has been associated with atypical femur fracture (AFF). However, the threshold of treatment duration leading to increased AFF risk is unclear. In a retrospective cohort of older women initiating BP, we compared the AFF risk associated with treatment for at least three years to the risk associated with treatment less than three years.

Methods

We used observational data from a large population of female members of an integrated healthcare system who initiated oral BP during 2002–2014. Women were retrospectively followed for incident AFF confirmed by radiologic adjudication. Demographic data, pharmacologic exposures, comorbidity, bone density, and fracture history were ascertained from electronic health records. Inverse probability weighting was used to estimate risk differences comparing the cumulative incidence (risk) of AFF if women discontinued BP within three years to the cumulative incidence of AFF if women continued BP for three or more years, adjusting for potential time-dependent confounding by the aforementioned factors.

Results

Among 87,820 women age 45–84 years who initiated BP (mean age 68.6, median T-score − 2.6, 14% with prior major osteoporotic fracture), 16,180 continued BP for three or more years. Forty-six confirmed AFFs occurred during follow-up in the two groups. AFF-free survival was greater for BP treatment < 3 years compared to treatment ≥3 years (p = 0.004 comparing areas under survival curves). At five years, the risk of AFF was 27 per 100,000 (95% confidence interval, CI: 8–46) if women received BP treatment < 3 years and 120 per 100,000 (95% CI: 56–183) if women received BP treatment ≥3 years (risk difference 93 per 100,000, 95% CI: 30–160). By ten years, the risks were 27 (95% CI: 8–46) and 363 (95% CI: 132–593) per 100,000 for BP treatment < 3 and ≥ 3 years, respectively (risk difference 336 per 100,000, 95% CI: 110–570).

Conclusions

Bisphosphonate treatment for 3 or more years was associated with greater risk of AFF than treatment for less than 3 years. Although AFFs are uncommon among BP-treated women, this increased risk should be considered when counseling women about long-term BP use. Future studies should further characterize the dose-response relationship between BP duration and incident AFF and identify patients at highest risk.

Use of Magnetic Resonance Imaging for Orthopedic Trauma and Infection in the Emergency Department

Conditions affecting the musculoskeletal system constitute a significant portion of medical emergencies in the United States, with traumatic injury and infection being two of the most common etiologies. Although physical examination and plain radiographs are often sufficient to guide diagnosis and treatment, there are myriad traumatic and infectious pathologies that are commonly missed or simply not detectable on plain radiographs. Advanced imaging is subsequently warranted for additional workup.Magnetic resonance imaging (MRI) has become an increasingly used imaging modality for musculoskeletal complaints in the emergency department due to its superior visualization of soft tissues, focal edematous changes, and occult osseous insults often not visible on plain radiographs. Although multiple studies have evaluated its utility in the workup of emergency musculoskeletal complaints, there remains a dearth of literature examining the use of MRI for certain occult diagnoses.Radiologists, emergency clinicians, and orthopedic surgeons must be knowledgeable of the indications for MRI in the emergency setting, as delayed diagnosis may contribute to increased morbidity and possibly mortality. This review summarizes the use of MRI in diagnoses relating to trauma or infection among patients presenting to the emergency department with a musculoskeletal complaint.

Musculoskeletal MRI of Nontraumatic Emergencies

A wide range of nontraumatic musculoskeletal conditions may require emergent or urgent management to avoid adverse clinical outcomes. These entities include bone and soft tissue infections, tissue necrosis, impending pathologic fracture or fungating tumor, and pseudoaneurysms. In this review, the magnetic resonance imaging appearance of these various entities is presented and discussed with the aim of improving radiologist and clinician recognition of the importance of key imaging findings in each case.

Solitary fibrous tumor of bone developing lung metastases on long-term follow-up

Solitary fibrous tumors are rare mesenchymal neoplasms of fibroblastic or myofibroblastic origin. Primary solitary fibrous tumors arising in bone are extremely rare and rarely metastasize. We present a case of solitary fibrous tumor where the diagnosis was delayed due to a failure to recognize the subtle, lytic lesion underlying a fracture of the left humerus. The patient underwent proximal humeral replacement and was followed closely with imaging of humerus and chest. A small lung metastasis was found on CT scan 38 months later and was resected. Two additional small metastases were found and resected 62 months after initial tumor resection. The purpose of this case report is both to highlight the radiologic challenges which can lead to overlooking a lytic lesion underlying a fracture and to show the importance of long-term follow-up in patients with solitary fibrous tumor.

[Radiologic diagnosis of pathologic fractures]

BACKGROUND

Pathologic fractures are fractures that occur without an adequate traumatic event due to focal benign or malignant skeletal lesions. The most common causes of pathologic fractures are cystic bone lesions, plasmocytoma or multiple myeloma, and the development of osseous metastases, which is increasing due to an aging general population and advances in cancer treatment. The differentiation of pathologic fractures from stress fractures, especially osteoporotic insufficiency fractures is crucial for correct treatment planning.

OBJECTIVES

This review intends to explain the imaging characteristics of pathologic fractures. Moreover, it explains the role of imaging when pathologic fractures are suspected. In addition, the Mirels' score and the SINS (Spinal Instability Neoplastic Score), which are powerful yet easy-to-use tools for the assessment of the fracture risk of benign or malignant bony lesions of the extremities and the vertebral column, shall be introduced.

MATERIALS AND METHODS

A PubMed literature search with the following terms was conducted: "pathologic fracture", "fatigue fracture", "insufficiency fracture", "treatment of pathologic fractures", "imaging of pathologic fractures", "fracture risk", "bone metastases", "MRI of pathologic fractures", "CT of pathologic fractures", "differentiation of pathologic and insufficiency fractures", "Mirels' score", "SINS" and "spinal instability neoplastic score".

RESULTS

The definitions of pathologic, fatigue, and insufficiency fractures are explained. Moreover, the role of imaging in the clinical workup of suspected pathologic fractures and the differentiation of pathologic fractures from fatigue or insufficiency fractures as well as common scoring systems to assess the fracture risk of pathologic fractures are described.