The enigma of stress fractures in the pediatric age: clarification or confusion through the new imaging modalities

Intra-epiphyseal stress injury of the proximal tibial epiphysis: preliminary experience of magnetic resonance imaging findings

Stress induced injuries affecting the physeal plate or cortical bone in children and adolescents, especially young athletes, have been well described. However, there are no reports in the current English language literature of stress injury affecting the incompletely ossified epiphyseal cartilage. We present four cases of stress related change to the proximal tibial epiphysis (PTE) along with their respective magnetic resonance imaging (MRI) appearances ranging from subtle oedema signal to a pseudo-tumour like appearance within the epiphyseal cartilage. The site and pattern of intra-epiphyseal injury is determined by the type of tissue that is affected, the maturity of the skeleton and the type of forces that are transmitted through the tissue. We demonstrate how an awareness of the morphological spectrum of MRI appearances in intra-epiphyseal stress injury and the ability to identify concomitant signs of stress in other nearby structures can help reduce misdiagnosis, avoid invasive diagnostic procedures like bone biopsy and reassure patients and their families.

Tibial stress phenomena and fractures: imaging evaluation

This study aims to evaluate the various imaging modalities used to diagnose tibial stress-fractures/phenomena and determine which of these are most useful and definitive. The plain film, computed tomography (CT), magnetic resonance (MR), and nuclear medicine findings in a 20-patient cohort, ranging from ages 10 to 21 years with an average of 16 years, were reviewed. The male to female ratio was recorded as was the incidence of right or left, or bilateral extremity involvement. Thereafter, each imaging modality was evaluated for positive findings. Twelve of the patients had pretibial swelling on plain films, 10 a thickened cortex, to a visible fracture on plain films and 13 had increased short-tau inversion recovery (STIR) signal in the post tibial (marrow) and pretibial (subperiosteum) areas on MR imaging. No CT studies were performed. One positive nuclear medicine study was available. Although there are a number of imaging modalities which can be used to evaluate the tibial stress/fracture phenomena problem, it would appear that plain films and MR studies are most useful. If plain films do not show a fracture and further information is required, an MR study is most appropriate.

Stress fractures in the young athlete: a pictorial review

Stress fractures are an uncommon but important source of pain and disability in young athletes. The presentation and differential diagnosis of stress fractures in young athletes differs from that of older athletes. This pictorial review outlines the pathogenesis and imaging features of stress fractures. Other pathologies that can mimic stress fractures and the advantages of the use of magnetic resonance imaging will be discussed. An imaging algorithm for a suspected stress fracture is suggested.

Scapular stress fracture initially masquerading as tumor or infection

We present a case of a scapular stress fracture in a 17-year-old athletic male that was initially thought to be a neoplasm. Radiographs showed a lesion at the neck of the glenoid with aggressive features. A subsequent MRI and bone scan supported a diagnosis of either tumor or infection. However, before a scheduled bone biopsy, a screening chest CT for pulmonary metastases revealed features of a healing stress fracture. The patient ceased intense athletic activity and four weeks later experienced a continued decrease in shoulder symptoms. A followup shoulder CT confirmed a healing fracture. This case illustrates how a stress fracture at an uncommon location may mimic a neoplasm. CT provides complementary information to radiography and MRI and helps establish a definitive diagnosis.

Displaced stress fracture of the femoral neck in young active adults

Stress fractures of the femoral neck in healthy individuals are rare and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders and, thereby, following amenorrhoea and osteoporosis. The majority of fractures of the femoral neck are undisplaced. However, they might progress into displaced fractures with avascular necrosis of the femoral head and following development of osteoarthritis as a probable consequence even when treated properly. Early diagnosis with MRI or radionuclide scanning in patients with a history of pain in the groin region during training might be crucial in detecting the fractures at early stages; thereby preventing possible complications following surgical treatment of displaced fractures. The authors present a report of two young adults who developed displaced fractures of the femoral neck and were treated with closed reduction and internal fixation.

Stress fractures of the femoral diaphysis in children: a report of 5 cases and review of literature

The authors report five new cases of the stress fracture of the femoral diaphysis in children. These injuries usually occurred without a history of recent increase of activity. Recently regained normal activity after long-term immobilization and a fibrous cortical defect were predisposing factors. The periosteal reactions were usually identified in the initial radiograph and were not confined to the medial cortex of the distal femur; they might occur in any part of the femoral diaphysis, and also concomitantly on the multiple cortex. The atypical radiographic presentations frequently required MRI for differential diagnosis. Even though the MRI may be confusing to the inexperienced observer, it can lead to the diagnosis of a stress fracture with confidence, negating the need for biopsy. Clinicians should be aware of this diagnostic entity in the differential diagnosis of femoral diaphyseal lesions in children because the occurrence might be more common than reported. Serial simple radiographic examinations taken at intervals to look for the evidence of progressive fracture healing and the restriction of activity or immobilization may be an adequate approach for management.

Distinction of Long Bone Stress Fractures from Pathologic Fractures on Cross-Sectional Imaging: How Successful Are We?

OBJECTIVE

The objectives of our study were to define CT and MRI features that distinguish pathologic fractures from stress fractures and to compare the performance of CT and MRI with radiography.

MATERIALS AND METHODS

Two reviewers retrospectively reviewed 45 MR images, 37 CT scans, and 43 radiographs in 59 patients (30 biopsy-proven pathologic fractures and 29 stress fractures followed to resolution). The features observed on MRI were abnormal bone marrow (well-defined, ill-defined); intracortical, periosteal, or muscle T1 or T2 signal; endosteal scalloping; and a soft-tissue mass. The features seen on CT were marrow abnormality and character (well-defined, ill-defined, permeative, moth-eaten), endosteal scalloping, periosteal reaction (benign, aggressive), and a soft-tissue mass. Reviewers rated their confidence for diagnosing a pathologic fracture on a 1-3 scale (< 50%, 50-95%, > 95% sure, respectively) with each technique. Performance of each technique was defined by reviewer accuracy and area under the receiver operating characteristic curve (Az); the frequency with which the MRI and CT features were associated with pathologic and stress fractures was calculated.

RESULTS

For both reviewers, accuracy for differentiating pathologic from stress fractures was highest on MRI (accuracy/Az: reviewer 1, 98%/0.97; reviewer 2, 93%/0.99); CT (reviewer 1, 88%/0.83; reviewer 2, 82%/0.90) was less accurate than radiography (reviewer 1, 94%/0.98; reviewer 2, 88%/0.96). On MRI, pathologic fractures compared with stress fractures exhibited well-defined T1 marrow signal (83% vs 7%, respectively; p < 0.001), endosteal scalloping (58% vs 0%, p < 0.001), muscle signal (83% vs 48%, p = 0.026), and a soft-tissue mass (67% vs 0%, p < 0.001). On CT, pathologic fractures compared with stress fractures exhibited marrow abnormality (84% vs 17%, respectively; p = 0.001), endosteal scalloping (44% vs 0%, p = 0.006), and aggressive periosteal reaction (36% vs 0%, p = 0.04).

CONCLUSION

MRI is useful for distinguishing pathologic from stress fractures, especially after inconclusive radiographic findings. Specifically, pathologic fractures exhibit well-defined T1 marrow alterations, endosteal scalloping, and adjacent soft-tissue abnormalities.

Imaging of stress fractures in the athlete

Osseous stress fractures and stress reactions represent the effect of abnormal repetitive stress on normal bone. An accurate and thorough clinical history and sequential radiographs often suffice 40 make the diagnosis especially when the fracture occurs in one of the common locations, such as the tibia, metatarsals, or calcaneus. In cases that are atypical in location or clinical presentation the authors rely more on MR imaging, radionuclide bone scanning, and occasionally CT. MR imaging detects early changes of osseous stress injury and allows precise definition of anatomy and extent of injury, and is the preferred modality for evaluating the continuum of osseous manifestations of stress injury. MR imaging is useful in evaluating shin splints, early osseous stress injuries, and overt stress fracture. In the elite athlete prompt diagnosis and early rehabilitation are the goals.

Bone scintigraphy in screening of torture survivors

BACKGROUND

In most developed countries, survivors of physical torture inflicted for political, religious, or ethnic reasons face ever more stringent review when seeking asylum. In Austria, asylum seekers are required by immigration authorities to undergo medical examination as part of the review. Bone scintigraphy can detect bone lesions that are not detectable clinically or radiologically. We assessed the value of bone scintigraphy as corroboration of alleged injuries.

METHODS

Human-rights organisations referred 25 asylum seekers to us from countries where torture is practised. We included patients who claimed to have been beaten by the security forces in their home country because of political or religious conviction or ethnic origin. Injuries had been inflicted 4 months to 5 years earlier. The patients (three women, 22 men) from 12 countries were categorised retrospectively into two groups: group A (n=12), tortured with blows from hard objects, and group B (n=13), tortured with blows from fists and kicks. We also used a control group of 25 individuals with the same age and sex distribution from the same countries who had no history of torture.

FINDINGS

In group A, bone scans showed abnormalities in the area of alleged injury in all patients, whereas radiography was positive in only five patients. In group B, bone scans in the alleged areas of damage were positive in seven patients, but radiography yielded no positive outcomes. Among the controls there was one abnormal scan due to a known coxarthrosis.

INTERPRETATION

Our preliminary results suggest that bone scintigraphy is a sensitive, non-invasive tool to document trauma some years after the actual injury.

Update on imaging of orthopedic infections

Although the diagnosis of infection is only a small part of the orthopedist's job description, it is a important part. This article discusses the fundamentals of orthopedic infections and highlights the refinements on this topic from a radiologic perspective. In addition to reviewing the imaging appearance of musculoskeletal infections in bone and the surrounding soft tissues, we focus on the advantages and disadvantages of five imaging methods: radiography, sonography, CT, scintigraphy, and MR imaging. Finally, we review three specific situations that have garnered substantial attention in recent medical literature: chronic recurrent multifocal osteomyelitis, musculoskeletal infections in AIDS patients, and pedal infections in diabetic patients.

Orthopedic pathology of the lower extremities: scintigraphic evaluation in the thigh, knee, and leg

Radionuclide imaging (RI) of the osseous and nonosseous structures of the thigh, knee, and leg provide important diagnostic and prognostic information upon which the orthopedic surgeon can base treatment planning and management decisions. 99mTc-MDP scintigraphy is essential in overuse injuries such as stress fractures and shin splints. RI is important in assessing complications of trauma. It is the only imaging modality able to assess the magnitude of physeal stimulus caused by femoral fractures and to predict a favorable or unfavorable outcome of leg length by semiquantitative analysis; SPECT imaging can detect and locate decreased metabolism associated with posttraumatic closure of the physeal plate to predict growth arrest and deformities. Three-phase bone imaging (TPBI) is essential to differentiate hypervascular from avascular nonunions and follow delayed union. In osteonecrosis of the knee, bone scintigraphy precedes radiography changes even in stage l of the disease. 99mTc-MDP and 99mTc-HIG imaging are powerful tools in determining the outcomes of osteoarthritis and rheumatoid arthritis, respectively. Bone scintigraphy can also detect chronic ligament and acute and chronic meniscal lesions. The combined use of TPBI, gallium-67 citrate imaging, and indium-111 or 99mTc-HMPAO labeled leukocytes is important to diagnose and differentiate acute from chronic osteomyelitis, and to detect infected knee prostheses. Thallium-201 chloride imaging and 99mTc-sestamibi imaging have an important role in the assessment of tumor response to chemotherapy and in the quantification of tumor viability.

Stress fractures in skeletally immature patients

Stress fractures are a common injury in an active population. As children become increasingly involved in organized sports, the recognition of stress fractures and differentiation from infections or neoplasms requires a knowledge of their most common sites, presentation, and clinical course. We retrospectively reviewed 34 stress fractures in 32 skeletally immature patients from June 1977 to May 1993. Age, fracture location, treatment, time to union or healing, associated conditions, complications, radiographs, and clinical outcome were recorded. Fifty percent of patients were involved in sports; the most common complaint was pain with activity. The most common site was the tibia (47%) followed by the fibula (21%) and femur (12%). All had resolution of symptoms and returned to normal activity. All but two healed with either activity modification or cast immobilization. The radiographic findings included early periosteal callus formation that rapidly consolidated to new bone on serial studies. A careful history, physical examination, and radiographs can help diagnose most common stress fractures in the skeletally immature individual and can differentiate stress fractures from infection or neoplasm with appropriate conservative treatment.

Stress fractures of the fibula in the first few years of life (report of six cases)

Fibular stress fractures in children in the first few years of life are not well known and are often confused with osteomyelitis or malignant bone tumour. This misdiagnosis is followed by nuclear scan, computerized tomography (CT), magnetic resonance (MR) imaging and even biopsy. All these investigations are unnecessary as plain X-rays show diagnostic radiographic findings and misdiagnosis is highly unlikely when they are evaluated in the context of clinical findings.

Where are we with nuclear medicine in pediatrics?

The practice of nuclear medicine in children is different from that in adults. Technical considerations including immobilization, dosing of radiopharmaceuticals, and instrumentation are of major importance. Image magnification and the capability to perform single-photon emission tomography are essential to performing state of the art pediatric nuclear medicine. New advances in instrumentation with multiple detector imaging, the possibility of clinical positron emission tomography imaging in children, and new radiopharmaceuticals will further enhance pediatric scintigraphic imaging. This review highlights advances in pediatric nuclear medicine and discusses selected clinical problems.

Fatigue fracture of the sacrum in a child

Fatigue fractures involving the sacrum are extremely rare, and to our knowledge no occurrence of such a fracture in a child has been reported in the English-language literature. These fractures may mimic primary bone tumours or infection, and it is important to make an accurate diagnosis so that unnecessary biopsy can be avoided. We report a fatigue fracture of the sacrum in an 11-year-old child following prolonged aerobic exercise.

Femoral stress fractures in children

Stress fractures reported in the medical literature almost exclusively affect young athletes, military recruits and patients with metabolic bone disease. The classification of stress-induced bone injury is somewhat confused and includes "fatigue" stress fractures which occur in previously normal bones and "insufficiency" stress fractures which occur in bones weakened by various causes. Femoral stress fractures in children are extremely rare, and we report 5 cases in young patients who sustained their injuries during the course of normal play activities. It is well-known that these lesions can simulate malignant lesions; however, we believe that careful review of the radiographs in the context of the clinical history can in many cases lead to the correct diagnosis being made and obviate the need for further intervention.

Stress fracture of the fibula in the first decade of life. Report of eight cases

Stress fracture of fibula in athletes and ballet dancers is a well recognised entity. Fibular fractures in children in the first decade of life who are not active in sport or ballet dancing are not well known and often diagnosed as osteomyelitis or malignant bone tumour. This misdiagnosis may be followed by CT, nuclear scan or MR. All these investigations are not necessary and biopsy if performed might even be misleading. The plain X-rays show diagnostic radiographic findings and a misdiagnosis is highly unlikely especially when they are evaluated in the context of clinical findings.