Hip arthroscopy in staging avascular necrosis of the femoral head

The purposes of this study were to evaluate how accurately current imaging modalities predict the quality of the articular surface in avascular necrosis (AVN) of the femoral head and to provide arthroscopic correlation to current staging modalities. An arthroscopic classification system, derived from the work of Marcus et al, was used to prospectively stage the articular surface in 23 hips with AVN using plain radiographs, magnetic resonance imaging (MRI), and arthroscopy. There was little correlation between all three diagnostic modalities. These findings were not statistically significant. Patients with stage IV disease had the widest variation in the appearance of the articular surface. This study shows poor correlation in the staging of AVN using current imaging techniques. Magnetic resonance imaging has been shown to be inadequate at assessing the articular cartilage. Therefore, either arthroscopy or direct visualization is required for accurate evaluation and staging, especially in stage IV disease.

MR imaging of patellar dislocation and relocation

Patellar dislocation and relocation (PDR) typically occurs suddenly after trauma or torsional stress on the extensor mechanism. Clinical evaluation after patellar dislocation/relocation usually reveals a swollen knee that is difficult to examine. Radiographs may show hemathroses and a minority of patients will have a chip fracture of the patella. Magnetic resonance (MR) imaging features seen with PDR include disruption or sprain of the medial retinaculum, lateral patellar tilt or subluxation, lateral femoral condylar and medical patellar osseous contusions, osteochondral injury, damage to Hoffa's fat pad, and joint effusion. Up to one third of patients will also show concomitant injury to the major ligaments of the knee or menisci. Without repair of the primary injury, redislocation occurs in greater than one half of patients. Consequently, surgical correction is often advocated. This article reviews the factors predisposing to PDR, the activities associated with PDR, the clinical, radiographic, and MR imaging features of PDR, and (briefly) therapy for this injury.

Neurologic dysfunction in patients with rheumatoid arthritis of the cervical spine. Predictive value of clinical, radiographic and MR imaging parameters

The aim of this study was to evaluate if subjective symptoms, radiographic and especially MR parameters of cervical spine involvement, can predict neurologic dysfunction in patients with severe rheumatoid arthritis (RA). Sequential radiographs, MR imaging, and neurologic examination were performed yearly in 46 consecutive RA patients with symptoms indicative of cervical spine involvement. Radiographic parameters were erosions of the dens or intervertebral joints, disc-space narrowing, horizontal and vertical atlantoaxial subluxation, subluxations below C2, and the diameter of the spinal canal. The MR features evaluated were presence of dens and atlas erosion, brainstem compression, subarachnoid space encroachment, pannus around the dens, abnormal fat body caudal to the clivus, cervicomedullary angle, and distance of the dens to the line of McRae. Muscle weakness was associated with a tenfold increased risk of neurologic dysfunction. Radiographic parameters were not associated. On MR images atlas erosion and a decreased distance of the dens to the line of McRae showed a fivefold increased risk of neurologic dysfunction. Subarachnoid space encroachment was associated with a 12-fold increased risk. Rheumatoid arthritis patients with muscle weakness and subarachnoid space encroachment of the entire cervical spine have a highly increased risk of developing neurologic dysfunction.

The role of hip arthroscopy in the evaluation of avascular necrosis

This prospective study evaluated the correlation between plain radiographs, magnetic resonance imaging (MRI), and diagnostic arthroscopy in the staging of avascular necrosis of the femoral head. Fifty-two hips in 46 patients were prospectively staged using radiographic and MRI staging systems. Patients subsequently underwent hip arthroscopy to visualize the articular surface prior to considering salvage of the femoral head and debride delaminated osteochondral fragments. Weighted Kappa analysis revealed only moderate correlation between MRI and plain radiographs (K=.11), MRI and arthroscopy (K=.21), and plain radiographs and arthroscopy (K=.19). Six (46%) of 13 patients with a radiographically apparent subchondral fracture demonstrated collapse of the articular surface at arthroscopy. Four (24%) of 17 hips with >2 mm of collapse of the femoral head on plain radiographs demonstrated fragmentation of the osteochondral surface of the femoral head at arthroscopy. In 5 patients with flattening of the femoral head, 3 patients had delamination of both the femoral and acetabular surfaces. In regard to labral pathology, 5 of 22 post-collapse hips also had large bucket handle tears of the labrum. Arthroscopy of the hip revealed osteochondral degeneration that was not detected by plain radiographs or MRI in 36% of post-collapse femoral heads.

Diffuse pigmented villonodular synovitis in a college football player

In retrospect, it is evident that our patient had signs of PVS on initial presentation: suprapatellar pouch effusion and swelling out of proportion to discomfort. In addition, his first MRI scan showed characteristics of PVS: thickening and enhancement. Difficulty in reaching the diagnosis of PVS was aided by his asymptomatic return to football. Further confusing the issue, his initial presentation was directly associated with trauma, which is not pathognomonic for PVS. In conclusion, diffuse pigmented villonodular synovitis can be recognized early on MRI scans, which should be carefully examined, especially in the presence of large suprapatellar effusions. Diffuse PVS can be successfully treated with arthroscopic subtotal synovectomy.

Are magnetic resonance flexion views useful in evaluating the cervical spine of patients with rheumatoid arthritis?

OBJECTIVE

To determine whether MR imaging in flexion adds value relative to imaging in the neutral position with respect to displaying involvement of the subarachnoid space, brainstem and spinal cord.

DESIGN AND PATIENTS

T1-weighted MR images of the cervical spine in 42 rheumatoid arthritis patients with cervical spine involvement were obtained and analyzed prospectively. We assessed changes between images obtained in the neutral position and following active flexion, especially horizontal atlantoaxial and subaxial motion, presence or absence of brainstem compression, subarachnoid space involvement at the atlantoaxial and subaxial level and the cervicomedullary angle. Vertical atlantoaxial subluxation and the amount of pannus were correlated with motion and change in subarachnoid space.

RESULTS

The flexion images showed horizontal atlantoaxial motion in 21 patients and subaxial motion in one patient. The flexion view displayed brainstem compression in only one patient. Involvement of the subarachnoid space increased at the atlantoaxial level in eight (19%) patients (P=0.004) and at the level below C2 in five (12%) patients (P=0.03). There were no patients with a normal subarachnoid space in neutral position and compression in the flexed position. The cervicomedullary angle changed significantly with flexion. Vertical atlantoaxial subluxation and the amount of pannus did not show a significant correlation with motion or subarachnoid space involvement.

CONCLUSION

MR imaging in the flexed position shows a statistically significant narrowing of the subarachnoid space at the atlantoaxial level and below C2. Cord compression is only observed on flexion views if the subarachnoid space in neutral position is already decreased. MR imaging in the flexed position might be useful, since subarachnoid space involvement may be an indicator for the development of neurologic dysfunction.

Magnetic resonance imaging of the musculoskeletal system. Part 9. Primary Tumors

Magnetic resonance imaging, because of its exquisite soft tissue contrast, has dramatically improved the ability to preoperatively stage primary osseous and soft tissue neoplasms. This technique also has allowed the monitoring of the effects of chemotherapy and the screening for recurrence of neoplasms. The role of magnetic resonance imaging in the preoperative evaluation of the patient with a suspected primary osseous or soft tissue neoplasm is outlined, instances where magnetic resonance imaging potentially may make a specific diagnosis are outlined, the importance of gadolinium enhancement as an adjunct to native magnetic resonance imaging is stressed, and an algorithm for followup of patients after chemotherapy or definitive surgical treatment is presented. In all cases, the magnetic resonance images should be correlated with the plain film, which is still an important aspect of the diagnosis of osseous lesions.

Usefulness of radiography in differentiating enchondroma from central grade 1 chondrosarcoma

OBJECTIVE

The purpose of this study was to evaluate clinical symptoms and radiographic features that allow radiologists to differentiate between enchondroma and central grade 1 chondrosarcoma. Such differentiation is important because of differences in management.

MATERIALS AND METHODS

Clinical symptoms and location and size of 35 enchondromas and 43 central grade 1 chondrosarcomas were analyzed. Radiographic features were assessed independently by three observers. The chi-square test and linear discriminant analysis were used to identify features with discriminating strength. Kappa values were calculated to validate the consistency of observations among observers. A consensus diagnosis made by histology and long-term follow-up was used as the standard.

RESULTS

No statistically significant correlation was found between clinical symptoms and the benign or malignant nature of the neoplasms. Grade 1 chondrosarcomas were more likely to be found in the axial skeleton and in flat bones. Also, chondrosarcomas were significantly larger than enchondromas (p < .001). Ill-defined margins and lobulated contours were the only morphologic features seen on radiographs that allowed significant discrimination (p = .004 and .009, respectively). An optimal combination of four radiographic features still left 72 of the 78 lesions with a 10-90% probability of malignancy, indicative of poor discriminating power. Kappa values generally showed poor to fair agreement.

CONCLUSION

Location in the axial skeleton and size greater than 5 cm are the most reliable predictors of central grade 1 chondrosarcoma. Morphologic features seen on radiographs and clinical symptoms do not improve the ability to differentiate between enchondromas and central grade 1 chondrosarcomas.

Dedifferentiated chondrosarcoma in patients with multiple osteochondromatosis: report of a case and review of the literature

Multiple osteochondromatosis (MOS) is a familial disorder of autosomal dominant transmission characterized by the development of multiple exostoses and often derangements of epiphyseal cartilage, sometimes resulting in long bone growth retardation. Patients with the disorder appear to be at increased risk for developing secondary chondrosarcomas. Rarely, dedifferentiated chondrosarcomas may also occur. We report a single case of a 27-year-old man with multiple osteochondromatosis who developed a fatal dedifferentiated chondrosarcoma. Radiographically, the neoplasm arose from the pelvis completely destroying the left pubic ramus. Subsequently, the patient underwent preoperative chemotherapy followed by a left external hemipelvectomy. On pathologic examination, the tumor was characterized by high-grade pleomorphic sarcoma sharply juxtaposed to a low-grade chondrosarcoma. The patient ultimately died of widespread metastatic sarcoma.

Magnetic resonance imaging of the musculoskeletal system. Part 4. The knee

Since its introduction to musculoskeletal imaging in the early 1980s, magnetic resonance imaging has proven to be an excellent technique for evaluating patients with knee problems. Studies have shown it to be accurate in the identification of abnormalities of the menisci, ligaments, patellofemoral joints, and other soft tissue and osseous structures in the knee. The main advantages of magnetic resonance imaging are its noninvasive nature and its high accuracy and negative predictive value in evaluating the menisci and anterior cruciate ligament. Magnetic resonance imaging has been shown to be useful in the detection and diagnosis of various traumatic and nontraumatic knee abnormalities. It has also proved useful in the diagnosis of occult or unsuspected bone lesions. Magnetic resonance imaging can therefore help in the selection of those patients who need therapeutic arthroscopy. There is evidence that magnetic resonance imaging of the knee is a cost effective screening technique when used in conjunction with the clinical findings in patients who are candidates for arthroscopy. Magnetic resonance imaging of the knee is still a relatively expensive modality.

Medial collateral ligament injuries of the knee: ultrasonographic findings

The aims of our study were (1) to describe the ultrasonographic findings of the injured medial collateral ligament of the knee and (2) to assess the usefulness of ultrasonography in both evaluating the presence and location of the medial collateral ligament injuries and predicting the prognoses for the patients. The study group consisted of 16 patients with the clinical diagnosis of medial collateral ligament injury. We also examined 20 knee joints in 10 volunteers who had no history of injury to the knee. To predict prognoses, we divided the patients into two groups on the basis of the location of medial collateral ligament injuries. A thickened and heterogeneously hypoechoic appearance of the medial collateral ligament was considered abnormal. The normal medial collateral ligament was a thin and moderately homogeneous hypoechoic band with an average thickness of 4.3 mm (range, 3.3 to 5.6 mm) at the femoral attachment and of 2.3 mm (range, 1.3 to 3.2 mm) at the tibial attachment. All injured medial collateral ligament structures were thickened and heterogeneously hypoechoic. According to the criteria for grading of medial collateral ligament injury with stress view, 10 patients had grade III medial collateral ligament tears, three had grade II tears, and none had grade I injuries. In 15 (94%) of 19 knees, a correct diagnosis could be made with ultrasonography. Ultrasonography is useful in evaluating isolated medial collateral ligament injuries and in predicting patient outcome on the basis of the location of the medial collateral ligament injuries.

Intraosseous pneumatocyst of the iliac bone

Intraosseous pneumatocyst of the iliac bone is usually an innocuous incidental finding with characteristic radiographic features. Because this entity is uncommon and has not been described in the orthopaedic literature, many orthopaedic surgeons are unfamiliar with the entity. Three cases of intraosseous pneumatocyst of the iliac bone are presented to illustrate some of the imaging features to assist in recognizing it for what it is: an innocuous incidental finding that should not prompt invasive procedures such as a biopsy.

Change in trabecular architecture as measured by fractal dimension

The objective of this work was to expose dried trabecular bone material to a decalcifying environment and to quantify the change in the spatial distribution of the bone with a fractal measure. Digitized radiographic images were produced from four separate slices of human vertebral bone as they dissolved within a solution of nitric acid. Pixel data from a region of interest (ROI) within the trabecular bone were used to estimate the time-dependent change in fractal dimension of the ROI as the bone dissolved. Results demonstrated that a change in the spatial distribution of trabecular material may be expressed in terms of a concurrently changing estimate of the fractal dimension.

Synovial osteochondromatosis

Primary or idiopathic synovial osteochondromatosis is an uncommon condition probably caused by synovial metaplasia and typically resulting in multiple calcified periarticular bodies. Synovial osteochondromatosis also may occur secondary to other joint disorders. This article reviews the pathogenesis, pathologic features, clinical features, and radiologic imaging of synovial osteochondromatosis. The differentiation of synovial osteochondromatosis from other conditions associated with periarticular calcified bodies is discussed.

Imaging of the total knee arthroplasty

We have reviewed the essentials of TKA imaging. Because the purpose of a knee arthroplasty is to relieve pain and improve function, radiographs should be viewed in the context of these goals.

Three-dimensional MRI of the glenoid labrum

The objective of this study was to assess the accuracy of three-dimensional (3D) magnetic resonance imaging (MRI) reformation in the evaluation of tears of the glenoid labrum complex (GLC). Fifty-five shoulders were evaluated by MRI using standard spin-echo sequences. Gradient-refocused-echo axial projections were used to assess the GLC on the two-dimensional (2D) studies. Three-dimensional Fourier transform multiplanar gradient-recalled imaging with a resolution of 0.7 mm was also performed in all patients. Independent analyses of the anterior and posterior labra were performed in a blinded manner for both the 2D and 3D studies by three experienced musculoskeletal radiologists. Observations of the imaging studies were compared with the videoarthroscopic findings. The appearance of the GLC was rated on a scale of 0 to 4 (0-2 = normal, 3, 4 = abnormal or torn). The diagnostic confidence was averaged from the three reader's scores. Anterior labral tears were effectively detected with sensitivities of 89% and 96% and specificities of 96% and 100% (P < 0.0001) for the 2D and 3D studies, respectively. For posterior labral tears, the sensitivity and specificity of the 2D method were 47% and 98%, respectively. The sensitivity and specificity of the 3D volume sequence were 53% and 98%, respectively. The lower sensitivity of both imaging methods for detecting posterior labral tears may be influenced by the smaller number (n = 5) of arthroscopically confirmed cases in our study and reflects the difficulty of visualizing the posteroinferior borders of the GLC with present MRI techniques.

Comparison of axial T1 spin-echo and T1 fat-saturation magnetic resonance imaging techniques in the diagnosis of chondromalacia patellae

To test the diagnostic value of T1 spin-echo and T1 fat-saturated magnetic resonance images (MRIs), we reviewed axial T1-weighted images with and without fat saturation in 20 patients with clinically suspected chondromalacia of the patella. All scans were obtained on 1.5-MR units. The scans were randomly ordered and reviewed independently at different times by two radiologists without knowledge of the arthroscopy results. The sensitivity of the individual techniques for detecting grade 3 or 4 chondromalacia patellae was 92% for fat-saturated axial T1-weighted images alone, and 67% for axial T1-weighted images without fat saturation. The sensitivity of the combined techniques was 100% for grades 3 and 4 and 90% for all grades (0 to 4). Chondromalacia patellae is diagnosed more accurately by using T1 fat saturation than by using T1 spin-echo images. With a combination of the two techniques, accuracy is 90% to 100%.

MR diagnosis of superior labral anterior posterior (SLAP) injuries of the glenoid labrum: value of routine imaging without intraarticular injection of contrast material

OBJECTIVE

Superior labral anterior posterior (SLAP) lesions are peculiar types of tears that involve the superior and anterior aspects of the glenoid labrum and extend posteriorly. The biceps tendon may also be involved in the injury. There have been conflicting reports in the literature about the value of MR imaging in depicting these injuries. Some authors have advocated imaging in special planes and, more recently, the use of intraarticular injection of contrast material to facilitate the diagnosis of SLAP injuries. Symptoms of SLAP injury of the glenoid labrum are nonspecific, and patients are often imaged according to routine imaging protocols that include images in axial, oblique coronal, and oblique sagittal planes using spin-echo pulse sequences. Intraarticular injection of contrast material is not part of routine MR imaging of the shoulder. We sought to determine the value of routine MR imaging without intraarticular contrast enhancement in the diagnosis of SLAP injuries of the glenoid labrum.

MATERIALS AND METHODS

The MR images of eight patients with arthroscopically proved SLAP lesions were selected for this study. The MR imaging appearance of the glenoid labrum, biceps tendon attachment, and rotator cuff tendons were retrospectively evaluated in the axial, oblique coronal, and oblique sagittal planes in each case. The findings were correlated with the surgical observations.

RESULTS

All eight patients showed an abnormal labrum on the coronal MR images, on 88% of the axial images, and on 50% of the sagittal images. An oblique or horizontal linear focus of increased signal was seen to traverse the labrum in 50% of the cases on sagittal images. Fifty percent of the cases also showed an intraarticular body, presumably representing the displaced fragment of a bucket-handle tear, on all imaging planes (the MR "Cheerio" sign).

CONCLUSION

Routine MR imaging of the shoulder without intraarticular injection of contrast material is useful in the diagnosis of SLAP injuries of the glenoid labrum.

MRI of knee ligaments

The stability of the knee depends on the integrity of its ligaments. Pain, clinical history, and nonspecific physical findings may hinder clinical diagnosis of acute ligamentous injury. Most major knee ligaments have uniform low signal intensity on all imaging sequences, and diagnosis of injury is based on periligamentous soft tissue edema, increased signal within the ligament, or disrupted structures. Correlation of of findings from routine sagittal, coronal, and axial MRI scans usually yields a definitive diagnosis of knee ligamentous injury. This article reviews normal anatomy, function, mechanism of injury, and normal and pathological MRI findings of the major knee ligaments.

Isolated subacromial bursal fluid on MRI of the shoulder in symptomatic patients: correlation with arthroscopic findings

Fluid in the subacromial bursa (SAB) is a common finding on magnetic resonance (MR) images of the shoulder, and the implications of this finding have not been clarified. We retrospectively reviewed and correlated the MR features with arthroscopic findings in 21 symptomatic patients who had fluid in the SAB on MR imaging without demonstrable rotator cuff tear. Rotator cuff impingement was the most frequent surgical finding (42.9%). Other frequent surgical observations were glenoid labrum abnormality (28.6%), bursitis (19%), and supraspinatus tendinitis (14.3%). Distribution of acromial types was similar to that reported by Bigliani et al., and impingement was evenly distributed among acromial types in our study population. We conclude that in our patient population group the MR finding of isolated SAB fluid in symptomatic patients is highly likely to be associated with the finding of other abnormalities in the shoulder joint at surgery.

MR imaging of patellar tendinitis

To identify magnetic resonance (MR) imaging characteristics of normal patellar tendons and those affected by tendinitis, the authors evaluated MR images obtained in 10 healthy volunteers, in 50 patients who underwent MR imaging for evaluation of knee structures other than the patellar tendon, in 11 patients with patellar tendinitis, and in two athletes with patellar tendon injuries. Normal tendons had uniformly low signal intensity on T1-, T2-, and proton-density-weighted images and displayed distinct margins, and the anteroposterior (AP) diameter slightly increased proximally to distally. It was concluded that the AP diameter of a normal tendon, in its proximal portion, should not exceed 7 mm. In patellar tendinitis, the tendon showed increased signal intensity on T1-, T2-, and proton-density-weighted images and increased AP diameter proximally. The margins of affected tendons were indistinct, especially posterior to the thickened segment. In all groups studied, women had thicker proximal tendons than did men.

Radiologic findings of diseases involving the maxilla and mandible

The purpose of this pictorial essay is to illustrate the radiologic appearances of diseases involving the maxilla and mandible. The high prevalence of dental disease results in inflammatory, infectious, and reactive processes that must be distinguished from more serious conditions with similar radiologic features. Because of their association with odontogenic tissues, lesions of the maxilla and mandible may have radiologic findings not seen in other bones. Furthermore, nonodontogenic cysts and tumors that occur elsewhere in the skeleton may exhibit unique radiologic characteristics when associated with teeth. This pictorial essay presents the radiologic characteristics of inflammatory lesions, developmental abnormalities, fibroosseous lesions, benign cysts and tumors, and malignant lesions of the maxilla and mandible.

Case report 733. Calcific tendinitis of the origin of the medial and lateral heads of the rectus femoris muscle and the anterior iliac spin (AIIS)

Calcific tendinitis at the site of origin of the rectus femoris muscle is a rare lesion. Presumed to be formed by deposition of hydroxyapatite crystals, this entity may be confused with other lesions such as os acetabuli or posttraumatic abnormalities. The characteristic location and appearance of the calcifications in a symptomatic patient with no history of trauma should allow diagnosis and subsequent symptomatic therapy.

Plain and computed radiography for detecting experimentally induced pneumothorax in cadavers: implications for detection in patients

Pneumothorax was induced in cadavers to determine the effects of patient positioning and imaging modality (conventional screen-film and computed radiography) on radiographic findings. Chest radiography, with cadavers in the supine frontal, erect frontal, and left lateral decubitus positions, was performed at baseline and after injection of incremental quantities of air into the pleural space. Five radiologists independently interpreted each radiograph. The ability of the radiologists to diagnose pneumothorax varied by cadaver position and depended on volume of air. Overall, the left lateral decubitus view was most sensitive (88%) for diagnosis of pneumothorax, followed by the erect (59%) and supine (37%) views. Receiver operating characteristic curves and multiple repeated measures analysis of variance revealed no statistically significant difference between diagnostic proficiency with conventional screen-film radiography and that with computed radiography. The authors conclude that the lateral decubitus view is superior to the erect and supine views for pneumothorax detection and that conventional and computed radiography perform similarly in pneumothorax detection.

Vacuum phenomenon simulating meniscal or cartilaginous injury of the knee at MR imaging

In five patients undergoing magnetic resonance imaging of the knee after athletic injuries, the authors identified a vacuum phenomenon that simulated medial meniscal or joint compartment cartilaginous abnormality. A cadaveric knee was injected with air, and the findings were re-created. The presence of air or gas between the articular surfaces of the tibia and femur can simulate meniscal or cartilaginous injury.

Malignant peritoneal mesothelioma in childhood with long-term survival

A diffuse, well-differentiated, malignant peritoneal mesothelioma (MPM) developed in a nine-year-old girl. She received limited chemotherapy and radiation therapy and is alive and well without clinical evidence of disease 109 months after diagnosis. The neoplastic cells stained immunohistochemically for cytokeratin and epithelial membrane antigen but were unreactive with B72.3, anti-carcinoembryonic antigen, and anti-Leu-M1. Ultrastructurally, the tumor cells had abundant desmosomes, numerous tonofilament bundles, and variable-length microvilli. These findings confirm the mesothelial nature of the cells. Features consistent with malignancy included DNA aneuploidy by flow cytometric analysis and diffuse peritoneal involvement. The three previously described survivors with MPM were also premenarchal girls. Some MPMs in premenarchal girls have an indolent biologic behavior similar to that of low-grade peritoneal serous neoplasia or well-differentiated papillary mesothelioma in adult women.

Cunninghamella bertholletiae: an unusual agent of zygomycosis

Cunninghamella bertholletiae shares many of the features typical of the other agents causing zygomycoses. Those who are immunocompromised constitute the major patient population at risk; the agents as a group are aggressive, the disease is often disseminated, and the pathologic picture of vascular invasion and tissue infarction is common. Unlike other agents of zygomycoses, Cunninghamella bertholletiae infection remains difficult to treat successfully even after early diagnosis and appropriate therapy.

Septic sacroiliitis due to Proteus mirabilis

This case demonstrates the difficulty frequently encountered in making an early diagnosis of septic sacroiliitis. The proper use of appropriate laboratory tests and radiologic examinations can narrow the differential diagnosis significantly, with confirmation resting on culture results. Appropriate antibiotic therapy will depend on the organism isolated. When confronted by the typical clinical findings and supporting ancillary data of septic sacroiliitis, the physician should consider the possibility of an unusual organism such as Proteus mirabilis and should direct antibiotic therapy accordingly.

Pneumothorax following transbronchial biopsy. Low diagnostic yield with routine chest roentgenograms

A chest roentgenogram is commonly obtained after a transbronchial biopsy to exclude a pneumothorax. We hypothesized that these routine chest roentgenograms rarely demonstrate a pneumothorax in patients who have neither symptoms nor fluoroscopic findings of lung collapse. To test this hypothesis, we studied 305 consecutive patients undergoing bronchoscopy with fluoroscopically guided TBB. No patient without symptoms and fluoroscopic findings suggesting lung collapse had a pneumothorax demonstrated on the post-biopsy chest roentgenogram. At the University of Virginia, routine chest roentgenograms failed to demonstrate a single unsuspected pneumothorax among all patients undergoing TBB during a period of nearly six years. Given this low incidence of unsuspected pneumothorax, we conclude that routine chest roentgenograms have a low diagnostic yield and may not be necessary in all patients after fluoroscopically guided TBB.

Bilateral protrusio acetabuli in sickle cell anemia

Extreme bilateral protrusio acetabuli is an unusual complication of hematologic disease. We have described a patient with sickle cell anemia who had this complication probably as a result of osteopenia. Thus sickle cell anemia should be added to the list of potential causes of protrusio acetabuli.

Intra-osseous ganglion. Report of four cases and review of the literature

Intraosseous ganglia are histologically identical to their soft tissue counterparts. Most commonly seen adjacent to the hip, ankles, knee, or wrist, they are often mistaken for other neoplasms occurring in the epiphysis. We discuss the characteristic clinical, radiological, and pathologic features of four cases of intraosseous ganglia. Intraosseous ganglia should be included in the differential diagnosis of well-demarcated lucent epiphyseal lesions of bone.

Acute bilateral diffuse pulmonary shadowing after evacuation of hydatid mole

Acute bilateral diffuse pulmonary shadowing complicates the resection of hydatid mole approximately 10% of the time. Etiologic factors include trophoblastic emboli, pulmonary emboli, high output congestive failure, and DIC. Prompt recognition and emergency oxygen therapy with PEEP are imperative for survival.