Parasymphyseal insufficiency fractures of the os pubis

Twelve parasymphyseal insufficiency fractures of the os pubis are described in eight osteopenic postmenopausal women, three of whom had rheumatoid arthritis. The fractures involved both right and left pubic bones in three women. Radiographically lesions often appear deceptively destructive and malignant. In six patients, biopsy was performed and showed no tumor. Biopsy can be avoided in an osteopenic woman with recent increased activity, pubic pain, and the characteristic pubic lesion.     

Vacuum phenomena in insufficiency fractures of the sacrum

Objective. Insufficiency fractures of the sacrum are found in women who have undergone radiation therapy to the lower abdomen as well as those suffering from osteoporosis of postmenopausal, steroid-induced, or primary biliary cirrhosis-related origin. Increased up-take in bone scintigraphy and osteolytic changes in these fractures can be misinterpreted as bone metastases, leading to unnecessary biopsies and other procedures in the ensuing search for non-existent primary tumor.Patients. In eight female patients averaging 69.4 years of age, insufficiency fracture of the sacrum was diagnosed by computed tomography (CT) and bone scintigraphy. Three underwent a total of five MRI examinations. Malignancy was excluded by histology in two patients and follow-up of at least 6 months in the remainder. Retrospective analysis of CT scans of 13 patients with metastases in the sacrum revealed no vacuum phenomena.Results. In seven of eight patients with insufficiency fracture of the sacrum, vacuum phenomena were shown on CT examination. The gas was localized centrally within the ventral part of the fracture in three patients; gas was located in ten adjacent sacro-iliac joints of six patients.Conclusions. The vacuum phenomenon may be an incidental finding in osteoarthritis of the sacro-iliac joint, but it has not been previously recognized in IFS. The presence of intra-articular vacuum phenomena in the sacro-iliac joints in combination with a sacral fracture and vacuum phenomena located within the sacral fracture supports a diagnosis of insufficiency fracture or may indeed be the clue by which this diagnosis is established. Insufficiency fractures of the sacrum are a well-known complication in women who have undergone radiation therapy of the pelvis or are suffering from postmenopausal, steroid-induced, or primary biliary cirrhosis-related osteoporosis [1–11]. These fractures are characterized by increased activity on radionuclide bone scans. The lateral masses of the sacrum contain large amounts of hematopoetic bone marrow and are therefore often the site of bone metastasis. Increased uptake in bone scintigraphy in lateral masses of the sacrum and osteolytic destructions on radiographs and computed tomography (CT), especially in patients with a history of a tumor elsewhere, are suggestive of skeletal metastasis, prompting biopsies and additional diagnostic procedures to find a primary tumor [2]. We present seven out of eight patients with insufficiency fractures of the sacrum, in whom we observed vacuum phenomena within the fracture or in the adjacent sacroiliac joints, indicating the benignity of the lesion. This phenomenon has not been recognized previously.     

Magnetic resonance imaging in osteomalacic insufficiency fractures of the pelvis

AIMS: To report the magnetic resonance imaging (MRI) findings of osteomalacic insufficiency fractures of the pelvis. MATERIALS AND METHODS: In all, 12 persons presenting with chronic pelvic pain and with a definitive diagnosis of osteomalacia (OM) were enrolled in this study. Radiological work-up included direct radiographs (n = 12), computed tomography (n = 5), scintigraphy (n = 12) and MRI (n = 12). The location of the insufficiency fractures and corresponding MRI appearances were evaluated. Depending on the presence or absence of signal intensity around the fractures, the lesions were grouped into active and chronic forms. RESULTS: A total of 34 insufficiency fractures were depicted on imaging studies. MRI demonstrated 33 of the lesions. All the insufficiency fractures were seen as a hypointense lines or fissures on T1- and T2-weighted and STIR MR images. There was a high frequency of insufficiency fractures at the sacrum and iliac bone (16/34, 47%). Overall, 11 chronic-type (no abnormal signal intensity around the fissure) and 22 active-type (abnormal signal intensity around the fissure) insufficiency fractures were detected by MRI. Follow-up MR examinations of 2 subjects showed that abnormal signal intensity had disappeared after appropriate treatment. CONCLUSION: The results of this study showed that the iliac and sacral bones are frequently involved in patients with OM. MRI can determine the clinical activity of the disease, and can monitor the response to treatment of the active type of insufficiency fractures.     

Role of MRI in the diagnosis of insufficiency fractures of the sacrum and acetabular roof

 Objective. To review the risk factors and the radiological appearance of insufficiency fractures of the sacrum and acetabular roof. Design and patients. Twenty patients with sacral and acetabular roof insufficiency fractures were reviewed retrospectively. There were 16 women (80%) and 4 males (age range 48–86 years, excluding an 8-year-old boy). Thirteen patients had a known tumour, and nine had received pelvic irradiation. All patients, except one who was asymptomatic, presented with low back or hip pain. In patients with a known tumor, metastases were suspected. Plain radiography (20), bone scintigrams (16), MR examinations (20), and bone densitometry (14) were performed. Nine patients also each had a CT scan. Results and conclusions. In three cases the CT scan performed 10–25 days after onset of symptoms was interpreted as normal. MR examination performed a few days after the CT scan showed in each of these three patients a fracture line with a band of edema. Scintigraphy was very sensitive, but the H-shaped pattern of sacral uptake, specific for an insufficiency fracture, was detected in only three of 16 cases. The earliest MR sign was medullary edema, seen as early as 18 days after the onset of symptoms. On spin echo (SE) T1-weighted images (T1WI), the hypointense signal of edema could mask a fracture line. On SE T2WI the fracture line could be detected within the hyperintense edema (10 of 17 patients with examinations including SE T2WI). However, in four patients a fracture of the sacrum was not seen on T2WI, these having been obtained in the axial plane. For this reason, intravenous gadolinium was injected, revealing a fracture line in 12 of 14 examinations, or fat suppression sequences were performed, revealing a fracture line in five of five cases. The total number of fractures detected was 17 [15 fractures of the sacrum (bilateral in 10 cases) and two of the acetabular roof]. At a later stage, the edema resolved and the fracture was clearly seen. The two cases of fracture of the acetabular roof were easily recognized at MRI, particularly in the sagittal plane.     

Intrafracture fluid: a new diagnostic sign of insufficiency fractures of the sacrum and ilium

MRI is generally regarded as being sensitive but non-specific for the detection of insufficiency fractures affecting the sacrum and pelvic ring. The finding of intrafracture fluid is described in two elderly patients with insufficiency fractures. This MR feature is believed to be a new diagnostic sign of these fractures affecting the sacrum and ilium.     

Insufficiency fractures of the sacrum

Insufficiency fractures of the sacrum are not uncommon. Shared imaging features on radionuclide bone scan, CT, and MR images include linear vertical abnormalities, and unilateral or bilateral distribution. This pattern may be considered sufficiently characteristic to allow a confident correct diagnosis to be made. Radiologists need to have a greater awareness of this condition.     

Time-dependent changes of insufficiency fractures of the sacrum: intraosseous vacuum phenomenon as an early sign

Sacral insufficiency fractures develop over a period of time and show time-dependent changes. We report on 15 CT examinations of 5 patients with early-stage insufficiency fractures of the sacrum. In 4 patients only irregular sclerosis without distinct fracture lines was present in 7 of 8 fractures. Of these 4 patients; 3 exhibited intraosseous gas inclusions in a ventral part of a lateral mass; 5 of 8 fractures disclosed a ventral cortical break. When distinct fracture lines had developed in 1 patient, intraosseous vacuum phenomenon had disappeared. Fracture lines evolve over weeks to months and show central bone absorption. The fractures can heal as demonstrated in 4 of 6 fractures in 3 patients, can persist over 1 year without significant changes or can progress to pseudoarthrosis with bone destruction similar to neuropathic joint disease. Intraosseous vacuum phenomena can persist to this stage. Intraosseous vacuum phenomenon is recognized as a potential finding in the early stage of sacral insufficiency fracture, which also is true for irregular sclerosis and ventral cortical disruption. Correspondence to: A. Stäbler     

Stress fractures in the spine and sacrum

Stress fractures of the pars, pedicle, and sacrum are important considerations in the differential diagnosis of lower back pain in the child or adolescent athlete. A thorough history and physical examination as well as a high index of suspicion are essential when assessing a patient with lower back pain. Diagnostic imaging, including radiographs, bone scans, CT scans, and other imaging modalities are important for further narrowing the diagnosis. The early identification and proper management of stress fractures of the pars, pedicle, and sacrum are integral in the prevention of stress fractures in the adolescent athlete population. This article reviews current concepts in the assessment and management of stress fractures of the lumbosacral spine, particularly of the pars (spondylolysis), pedicles, and sacrum.     

Radiation-induced insufficiency fractures of the pelvis: evaluation with 99mTc-methylene diphosphonate scintigraphy.

99mTc-methylene diphosphonate (99mTc-MDP) bone scans in 80 patients, 30-80 years old (average, 62 years old) with uterine cancer who received high doses of radiation (10-60 Gy; average, 46 Gy) were reviewed retrospectively to evaluate the frequency of pelvic insufficiency fractures caused by radiotherapy and to study the appearance of the fractures on bone scans. Bone scans in 29 of 80 patients showed abnormalities in the pelvis: insufficiency fractures were identified in 27 patients (34%) and osseous metastases were found in two patients (3%). The fractures and metastases were diagnosed by CT and were confirmed by observing the patients' clinical courses. Fractures were identified in 27 (39%) of 69 postmenopausal women and in none of 11 premenopausal patients (p greater than .05). Fractures were found in 21 (84%) of 25 patients who had pelvic pain and in six (11%) of 55 patients who were asymptomatic (p greater than .001). Scintigrams in patients with fractures showed more than one fracture in most patients (85%), and fractures were often symmetric (67%). Scintigrams in two patients with osseous metastases showed increased activity in an iliac wing that was outside the radiation field. Our results suggest that a marked increase in insufficiency fractures occurs after radiation therapy, especially in postmenopausal patients. A symmetric area of increased uptake of radionuclide is a characteristic scintigraphic appearance of an insufficiency fracture.     

骶骨骨折的形态学特点及生物力学研究

目的探讨骶骨骨折的形态学及生物力学特点，为临床手术治疗提供科学依据。方法采集人体新鲜骨盆骨骼标本10具，行动态冲击试验和静态压缩试验，测量动态骨折时的一系列动力学参数，确定骨折的动力学特性；并取骶骨翼骨折块、骶骨孔块和骶边缘骨折块，进行组织学观察。结果(1)骶骨骨折的形态与受到冲击能量大小有关。低能的冲击加载，大都是发生髂骨或髋臼、髋髂嵴骨折。当高能量冲击时，骶骨发生以下三种方式骨折(按Denis骶骨骨折分类)：Ⅰ型骨折为骶骨翼骨折，Ⅱ型骨折为骶骨孔骨折，Ⅲ型骨折为中央椎管骨折，Ⅰ型、Ⅱ型和Ⅲ型骨折均可累及一侧神经根损伤或两侧神经根损伤。(2)骶骨的动态破坏机制与静态破坏机制两者在力学性质上有很大的不同，不但极限载荷不同，而且前者随应变速率的提高而快速增加，冲击能量达到25J以上会产生劈裂状通过骶骨孔骨折，并累及神经根损伤；当低于20J时，以发生髂骨骨折和骶骨骨折为多，处于20～25J之间易产生Ⅰ型骨折；而静态试验大多为髂骨或髋臼骨折；(3)骶骨的骨板开裂，层状交劈裂，分离哈佛板呈脆性断裂，导致骨板分离，也有少数横断骨板，形成裂隙错位。结论动态冲击试验以骶骨DenisⅠ型和Ⅱ型骨折居多，常累及一侧或两侧神经根损伤，骶骨骨折与其微观结构形态、骨小梁分布、骨陷窝与哈佛系统相联系。而静态压缩试验大多为髂骨或髋臼骨折，周围组织损伤轻。     

Avulsion fractures of the pelvis

Avulsion fractures of the pelvic apophyses are seen infrequently but they show a consistent pattern in mechanism, patient's age, symptoms, physical findings, and roentgenographic appearance. Some disagreement exists in the literature concerning the treatment of these fractures. This study indicates that early diagnosis and a carefully directed nonoperative treatment program will produce positive results for avulsion fractures of the pelvis. Twenty-seven cases of acute avulsion fracture of the pelvis were successfully treated in a directed nonoperative program.     

Computed tomography for occult fractures of the proximal femur,pelvis, and sacrum in clinical practice: single institution,dual-site experience

Purpose

The purpose of this study was to evaluate the diagnostic performance of CT for assessment of occult fractures of the proximal femur, pelvis, and sacrum.

Materials and methods

A retrospective review was performed on patients who received a CT of the hip or pelvis for suspected occult fracture after negative or equivocal radiographs performed within 24 h. The official radiology report was utilized for the determination of CT findings and calculation of sensitivity and specificity. Surgical reports, MRI reports, and clinical follow-up were used as the standard of reference. Sensitivity and specificity were calculated with 95% confidence intervals.

Results

Seventy-four patients received CT of the hip or pelvis for clinical concern for occult fracture after negative or equivocal radiographs. By the reference standard, a total of 40 fractures were present in 25/74 (33.8%) patients, including 35 conservatively treated fractures of the greater trochanter, pelvis, and sacrum, and 5 operatively treated proximal femoral fractures. A total of 14/74 (18.9%) of patients had an MRI within 1 day of CT. MRI identified an operatively treated femoral neck fracture not seen on CT and an operatively treated intertrochanteric fracture, which CT described as a greater trochanteric fracture. There were two false negative conservatively treated pelvic fractures not seen on CT but diagnosed on MRI. On a per-patient basis, CT had an overall sensitivity of 88% (22/25; 95% confidence intervals 69–97%), specificity of 98% (48/49; 95% confidence intervals 89–100%), and negative predictive value of 94%. For the five operative proximal femoral fractures, the sensitivity of CT was 60% (3/5; 95% confidence intervals 15–95%), specificity was 99% (68/69; 95% confidence intervals 92–100%), and negative predictive value was 97%.

Conclusions

In the clinical setting of suspected occult fracture, the sensitivity of clinical CT reports for detection of any type of fracture of the proximal femur, pelvis, or sacrum was 88%. For the small number of operatively treated proximal femoral fractures seen in the study, sensitivity of CT was 60% (3/5) and negative predictive value was 97%, although the relatively few patients needing fixation precludes statistical analysis.

     

Radiation induced fractures of sacrum: CT diagnosis

Sacral insufficiency fracture due to bone atrophy may develop as a complication of irradiation of pelvic malignancies. Pain is the presenting symptom and the clinical diagnoses most often considered are recurrence of the original malignancy and metastatic disease. Computed tomography provides the most specific information helpful for the detection of these fractures and for exclusion of recurrent malignancy.     

Iliac insufficiency fractures

Twenty-five post-menopausal women with one or more insufficiency fractures of the pelvic ring are reported. In 80% of cases the fractures were multiple and a total of 79 insufficiency fractures was identified. Twelve iliac insufficiency fractures were present in 11 patients located at one of three sites: above and parallel to the acetabular roof ("supra-acetabular"), extending diagonally across the iliac ala from the greater sciatic notch ("oblique iliac"), and adjacent to the sacro-iliac joint ("superomedial iliac"). The plain radiographic appearances of these iliac fractures were typically subtle with ill defined medullary sclerosis, due to trabecular compression, the cardinal sign. Scintigraphy revealed the fractures as foci of increased activity which, in the presence of multiple pelvic insufficiency fractures, may be mistaken for metastatic disease. Computed tomography can be helpful in confirming the presence of suspected fractures, revealing further occult fractures and also excluding the likelihood of malignancy.     

Supraacetabular insufficiency fractures

Insufficiency fractures in the supraacetabular region were identified in five women, aged 55-83 years. Factors contributing to the diminished resistance of their bones included postmenopausal osteoporosis, steroid therapy, radiation therapy, and rheumatoid arthritis. The supraacetabular fractures were seen on routine radiographs as hazy bands of sclerosis located immediately above and parallel to the acetabular roof. All five patients had additional fractures in the spine or pelvis. Supraacetabular insufficiency fractures may be an unsuspected cause of hip pain, especially in older women.     

Acetabular insufficiency fractures

Isolated acetabular insufficiency fractures are relatively uncommon occurrences that are difficult to diagnose if not suspected. Patients may present with variable signs and symptoms including emergent, incapacitating hip pain. Plain radiography is typically negative. Early diagnosis is important because most patients respond well to conservative therapy. This report describes three cases of isolated insufficiency fractures of the acetabulum diagnosed by magnetic resonance imaging (MRI).