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Douglas R Pedersen,1 Georges Y El-Khoury,2 Dan R Thedens,3 Mothana Saad-Eldine,1 Phinit Phisitkul,1 Annunziato Amendola4 1Department of Orthopaedics and Rehabilitation, 2Department of Radiology, University of Iowa Hospitals and Clinics, 3Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA, 4Department of Orthopaedics and Sports Medicine, Duke University Medical School, Durham, NC, USA Background: Bone contusions are frequently encountered in magnetic resonance imaging (MRI) evaluation of knee anterior cruciate ligament (ACL) injuries. Their role as indicators of injury severity remains unclear, primarily due to indeterminate levels of joint injury forces and to a lack of preinjury imaging.Purpose: The purpose of this study was to 1) quantify bone contusion pathogenesis following traumatic joint injuries using fixed imaging follow-ups, and 2) assess the feasibility of using longitudinal bone contusion volumes as an indicator of knee injury severity.Study design: Prospective sequential MRI follow-ups of a goat cohort exposed to controlled stifle trauma in vivo were compared to parallel clinical MRI follow-ups of a human ACL tear patient series.Methods: Reproducible cartilage impact damage of various energy magnitudes was applied in a survival goat model, coupled with partial resection of anterior portions of medial menisci. Both emulate injury patterns to the knee osteochondral structures commonly encountered in human ACL injury imaging as well as instability from resultant ligament laxity. Longitudinal clinical MRI sequences portrayed stifle bone contusion evolution through 6 months after the inciting event.Results: In the first 2 weeks, biological response variability dominated the whole-joint response with no apparent correlation to trauma severity. Control goats subjected to partial meniscectomy alone exhibited minimal bone response. Thereafter, 0.6 J impact bone contusions portrayed a faster rate of resolution than those induced by 1.2 J cartilage impacts.Conclusion: Bone contusion sizes combined with time of persistence are likely better measures of joint injury severity than isolated bone contusion volume. Keywords: bone contusion, contusion pathogenesis, anterior cruciate ligament, magnetic resonance imaging, knee, knee injury severity

Purpose: To retrospectively assess the diagnostic efficacy of radiography in detecting vertebral body fractures of the thoracic spine compared with MDCT, to assess the confounding factors reducing the diagnostic efficacy, and to investigate the outcomes of radiographically overlooked patients.Materials and Methods: Two hundred fifty-five patients suspected of thoracic spine fractures were enrolled. We assessed the diagnostic efficacy of radiography for the patients sub-grouped based on five confounding factors: chest abnormalities, head injuries, cervical spine fractures, upper extremity injuries, and age of 65 years or older. We investigated the outcomes of radiographically overlooked patients.Results: Three hundred fifty-one vertebral body fractures were detected. The per-fracture sensitivities and specificities were 55 % and 94 % for vertebral body fractures and 41 and 99 % for unstable fractures. In patients with upper extremity injuries or aged 65 years or older, radiography was less sensitive in detecting the unstable fractures (P < 0.05). Nineteen patients were overlooked by radiography; two had neurological deficits and needed surgical fixation; 15 with no neurological deficit were conservatively treated with uneventful outcomes.Conclusion: Radiography had low sensitivity but high specificity. In daily practice, primary use of MDCT is beneficial for patients with neurological deficit or upper extremity injuries or elderly patients. [ABSTRACT FROM AUTHOR]

Objective: To date semiquantitative whole-organ scoring of knee osteoarthritis (OA) relies on 1.5 Tesla (T) Magnetic resonance imaging (MRI) systems. Less costly 1.0 T extremity systems have been introduced that offer superior patient comfort, but may have limitations concerning field-of-view and image quality. The aim of this study was to compare semi-quantitative (SQ) scoring on a 1.0 T system using 1.5 T MRI as the standard of reference.Methods: The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of individuals who have or are at high risk for knee OA. A sample of 53 knees was selected in which MRI was performed on a 1.0 T extremity system as well as on a 1.5 T scanner applying a comparable sequence protocol. MRIs were read according to the Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Agreement was determined using weighted kappa statistics. Sensitivity, specificity and accuracy were assessed using the 1.5 T readings as the reference standard. In addition the number of non-readable features was assessed.Results: Agreement (w-kappa) for seven main WORMS features (cartilage, bone marrow lesions (BMLs), osteophytes, meniscal damage and extrusion, synovitis, effusion) ranged between 0.54 (synovitis) and 0.75 (cartilage). Sensitivity ranged between 68.1% (meniscal damage) and 88.1% (effusion). Specificity ranged between 63.6% (effusion) and 96.4% (BMLs). Although the overall rate of non-readable features was very low, it was higher for the 1.0 T system (1.9% vs 0.2%).Conclusions: Semiquantitative whole organ scoring can be performed using a 1.0 T peripheral scanner with a moderate to high degree of agreement and accuracy compared to SQ assessment using a 1.5 T whole body scanner. Our results are comparable to the published inter- and intra observer exercises obtained from 1.5 T systems. Sensitivity to change of longitudinal scoring was not evaluated in this cross-sectional design and should be investigated in future validation studies. [ABSTRACT FROM AUTHOR]

When interpreting musculoskeletal radiographs, a radiologist must be able to identify a lytic lesion and provide a definitive diagnosis or a reasonable differential diagnosis for the lesion. This article addresses these issues and details a rational and systematic approach to such lesions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to make a direct comparison between lumbar spine radiographs of incoming college football players and of an age-matched control group to determine whether there is a higher prevalence of lumbar spine abnormalities in football players before competing at the Division I level. We reviewed 187 lumbar spine radiographs. Of these, 104 were taken as a standard part of the preparation physical examination for incoming college football players. The remaining 83 radiographs were taken during routine preemployment physicals at a local factory. Each radiograph was read independently by three separate orthopaedic radiologists in a blinded fashion. Data were collected and statistically evaluated for 13 variables. The rate of spondylolysis was only 4.8% in our group of athletes and 6.0% in the control group (not significantly different). Only in the category of degenerative changes was a significant difference found. The control group had a 16.9% incidence of disk space narrowing and spurring and the football players had a 6.7% incidence. The remainder of the variables were not significantly different between the two groups. Our findings differ from previously published reports and indicate that football players entering college at the Division I level may have a similar prevalence of radiographic lumbar spine abnormalities, including spondylolysis and spondylolisthesis, as age-matched controls. [ABSTRACT FROM AUTHOR]

Fractures of the lower extremity are common reasons for visits to family physicians. Some lower extremity fractures are especially likely to be missed. Examples of lesions that commonly go unrecognized include sacral insufficiency or fatigue fracture, fracture of the femoral neck (especially if the fracture is nondisplaced and/or impacted), tibial plateau fracture, Segond fracture (vertical fracture of the lateral tibia), patellar fracture, calcaneal fracture of the foot, Lisfranc fracture/dislocation of the tarsometatarsal apparatus, and Jones fracture of the fifth metatarsal. Lower extremity fracture in children may suggest the possibility of child abuse, especially in the case of multiple or bilateral fractures. [ABSTRACT FROM AUTHOR]

Family physicians often are required to evaluate patients who present with acute skeletal trauma. The first of this two-part series discusses the features and evaluation of some commonly missed fractures and dislocations of the upper limb, excluding the hand. Dislocations of the sternoclavicular joint are infrequent and often missed. Clavicular fractures in adults usually are not hard to diagnose. Acromioclavicular joint dislocations represent about 10 percent of all dislocation injuries to the shoulder girdle. Forty percent of all dislocations occur at the glenohumeral joint. Scapular fractures are often a result of significant force. Multiple views should be obtained in adults with a suspected fracture of the elbow. Complications in fractures of the wrist are strongly related to the location of the fracture. [ABSTRACT FROM AUTHOR]

Skeletal dysplasia encompasses a heterogeneous group of over 400 genetic disorders. They are individually rare, but collectively rather common with an approximate incidence of 1/5000. Thus, radiologists occasionally encounter skeletal dysplasias in their daily practices, and the topic is commonly brought up in radiology board examinations across the world. However, many radiologists and trainees struggle with this issue because of the lack of proper resources. The radiological diagnosis of skeletal dysplasias primarily rests on pattern recognition-a method that is often called the "Aunt Minnie" approach. Most skeletal dysplasias have an identifiable pattern of skeletal changes composed of unique findings and even pathognomonic findings. Thus, skeletal dysplasias are the best example to which the Aunt Minnie approach is readily applicable., (© 2021. The Author(s).)

Purpose: The satisfaction-of-search (SOS) effect occurs when an abnormality on an image is missed because another is found. The aim of this experiment was to test whether severe distracting fractures control the magnitude of SOS on other fractures when both appear in a single CT image., Methods: The institutional review board approved this study. The experimental (SOS) condition included 35 cervical spine CT cases, all of which contained severe cervical spine injuries. For each of these cases, a similar case was found that had no injuries. Image modification software was developed to add simulated fractures to each pair of cases, with and without a major injury. Sixteen different minor fractures were added to 16 of the 35 pairs of images. The 35 cases without native injuries constituted a control (non-SOS) condition mixed in a random order. Twenty radiologists read 35 mixed cases in each of two sessions. False-positive evaluations were collected only for cases without simulated fractures., Results: An SOS effect on the detection of simulated fractures was not observed. There was a nonsignificant (P = .07) finding of poorer detection in the presence of cases with severe injuries. However, the magnitude of the effect was no greater than has been observed for less severe distracting injuries., Conclusions: The outcome agrees with the results of two previous experiments that failed to yield an SOS effect associated with detecting severe injuries, suggesting that the severity of a distracting injury does not determine whether a second injury is discovered., (Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

More children are participating in organized and recreational athletics at a younger age. It has been well documented that increased athletic specialization and year-round activities have resulted in higher incidences of overuse injuries, including stress fractures and stress reactions. Initially, stress fractures can be radiographically occult. Continued stress on the injured bone or cartilage can lead to progressive radiographic changes. Because of the prevalence of these injuries, both orthopedic surgeons and radiologists should be aware of the radiographic and magnetic resonance imaging (MRI) features of common stress fractures in children. This article reviews frequently encountered stress fractures involving various bones in the pediatric population.

Background: Use of three-dimensional (3D) color volume-rendered (VR) images has been reported to be more time-efficient compared to that of cross-sectional computed tomography (CT) images for the diagnosis of peroneal tendon dislocation. However, the diagnostic performance of this technique has not been studied., Purpose: To test diagnostic accuracy of 3D color VR CT images of ankle for peroneal tendon dislocation in patients with acute calcaneal fractures., Material and Methods: The study consisted of 121 ankle CT studies from 105 consecutive patients (85 men, 20 women; mean age, 42 years; age range, 16-75 years) with acute calcaneal fractures. Peroneal tendon dislocation was diagnosed on multiplanar CT images by consensus of two experienced musculoskeletal radiologists, which served as the reference standard. Three other musculoskeletal radiologists independently reviewed 3D images alone on a workstation. The readers determined whether or not there was peroneal tendon dislocation using three degrees of certainty (definite, probable, and possible). Diagnostic performance of 3D images for peroneal tendon dislocation was evaluated by calculating the sensitivities, specificities, and area under the receiver-operating characteristic (ROC) curves., Results: Forty-eight (40%) out of 121 studies showed peroneal tendon dislocation based on the expert readings using multiplanar reformatted images. Sensitivities/specificities of 3D images measured 0.92/0.81, 0.88/0.90, and 0.81/0.92 for three readers, respectively. The area under the proper binormal ROC curve based on all three readers (0.93, 0.94, and 0.92) measured 0.93 with a 95% confidence interval of 0.89-0.98., Conclusion: Diagnostic accuracy of 3D images is comparable to, but not as good as that of MPR images for the diagnosis of peroneal tendon dislocation in patients with acute calcaneal fractures., (© The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Objective: To examine the cross-sectional association of whole-knee synovitis assessed by contrast-enhanced magnetic resonance imaging (CEMRI) with radiographic tibiofemoral osteoarthritis (OA), non-CEMRI-assessed cartilage damage, and meniscal status., Methods: Multicenter Osteoarthritis Study (MOST) is a cohort study of people with or at high risk of knee OA. Subjects are a subset of MOST who volunteered for both CEMRI and non-CEMRI. Using CEMRI, synovitis was assessed at 11 sites and graded 0-2 at each site. Presence of "whole-knee synovitis" was defined as the synovitis score of ≥ 1 at any site from each knee. Cartilage and meniscal damage was evaluated using non-CEMRI based on the Whole Organ MRI Score. Logistic regression was used to assess associations of synovitis with radiographic OA (Kellgren-Lawrence grade ≥ 2), widespread cartilage damage, and meniscal damage, adjusting for age, sex, and body mass index (BMI). Additional analyses were performed excluding subjects who had chondrocalcinosis on radiography and those taking antiinflammatory medications., Results: Four hundred four subjects were included (mean age 58.8 ± 7.0 yrs, BMI 29.6 ± 4.9 kg/m(2), 45.5% women). On CEMRI, the maximum synovitis score across 11 sites in each knee was 0 in 106 knees (26.2%), 1 in 135 (33.4%), and 2 in 163 (40.4%). Synovitis was associated with radiographic OA [adjusted OR (aOR) 3.25, 95% CI 1.98-5.35] and widespread cartilage damage (aOR 1.91, 95% CI 1.24-2.92). Severe meniscal damage showed a borderline significant association with synovitis (aOR 1.74, 95% CI 0.99-3.04). Additional analyses as described did not notably change the results., Conclusion: CEMRI-detected synovitis is strongly associated with tibiofemoral radiographic OA and MRI-detected widespread cartilage damage.

Tophaceous gout presenting as a soft tissue mass in an unusual location can pose a diagnostic challenge for radiologists. Tophi sometimes occur in a variety of unusual anatomic locations making them difficult to distinguish from tumors such as sarcomas. We report two cases of gout in the extensor mechanism of the knee, with imaging findings that were initially concerning for a neoplasm. One mass occurred in the patellar tendon and the other mass involved the quadriceps tendon. Both lesions had enigmatic imaging findings and to arrive at a definitive diagnosis, incisional biopsies were performed.

Objective: Synovitis is thought to be a secondary phenomenon in the osteoarthritis (OA) process and the menisci might be triggers of localized synovitis. The aim was to assess the cross-sectional associations of posterior horn meniscal damage with perimeniscal synovitis, and with synovitis posterior to the posterior cruciate ligament (PCL) using contrast enhanced (CE) MRI., Design: The Multicenter Osteoarthritis (MOST) Study is a longitudinal observational study of subjects with or at risk for knee OA. Subjects are a subset of MOST who were examined with 1.5T CE MRI and had semiquantitative synovitis (scored from 0 to 2 at 11 locations) and meniscal readings (scored with WORMS from 0 to 4) available. Logistic regression was used to assess the association of posterior meniscal damage and perimeniscal synovitis in the same compartment, and between posterior meniscal damage and synovitis posterior to the PCL., Results: Three hundred and seventy seven knees were included (mean age 61.1 years±6.9, mean BMI 29.6±4.9, 44.3% women). The odds for ipsi-compartmental perimeniscal synovitis were increased for knees with medial posterior horn meniscal damage (adjusted odds ratio [aOR] 2.5, 95% confidence intervals [95% CI] 1.3,4.8), but not for lateral damage (aOR 1.7, 95% CI 0.4,6.6). No positive associations were found for meniscal damage and presence of synovitis posterior to the PCL (aOR 0.9, 95% CI 0.6,1.5)., Conclusions: Meniscal damage of the posterior horns is associated with ipsi-compartmental perimensical synovitis. No associations were found for posterior horn meniscal damage with synovitis posterior to the PCL, which suggests that synovitis posterior to the PCL is likely to be triggered by different pathomechanisms., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: To assess the diagnostic performance of signal changes in Hoffa's fat pad (HFP) assessed on non-contrast-enhanced (CE) magnetic resonance imaging (MRI) in detecting synovitis, and the association of pain with signal changes in HFP on non-CE MRI and peripatellar synovial thickness on CE MRI., Methods: The Multicenter Osteoarthritis (MOST) Study is an observational study of individuals who have or are at high risk for knee OA. All subjects with available non-CE and CE MRIs were included. Signal changes in HFP were scored from 0 to 3 in two regions using non-CE MRI. Synovial thickness was scored from 0 to 2 on CE MRI in five peripatellar regions. Sensitivity, specificity and accuracy of HFP signal changes were calculated considering synovial thickness on CE MRI as the reference standard. We used logistic regression to assess the associations of HFP changes (non-CE MRI) and synovial thickness (CE MRI) with pain from walking up or down stairs, after adjusting for potential confounders., Results: A total of 393 subjects were included. Sensitivity of infrapatellar and intercondylar signal changes in HFP was high (71% and 88%), but specificity was low (55% and 30%). No significant associations were found between HFP changes on non-CE MRI and pain. Grade 2 synovial thickness assessed on CE MRI was significantly associated with pain after adjustments for potential confounders., Conclusion: Signal changes in HFP detected on non-CE MRI are a sensitive but non-specific surrogate for the assessment of synovitis. CE MRI identifies associations with pain better than non-CE MRI., (Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of this experiment was to test whether radiographs of major injuries, those having serious consequences for life and limb, produce a satisfaction-of-search (SOS) effect on the detection of subtle, nondisplaced test fractures., Methods: Institutional review board approval and informed consent from 24 participants were obtained. Seventy simulated patients with multiple trauma injuries were constructed from radiographs of 3 different anatomic areas demonstrated only skeletal injuries. Readers evaluated each patient under 2 conditions: first, in the non-SOS condition, no injuries were present in the first anatomic images, and second, in the SOS condition, the first anatomic images included major injuries requiring immediate medical intervention. The SOS effect was measured on detection accuracy using receiver operating characteristic analysis for subtle test fractures presented on examinations of the second or third anatomic areas., Results: Satisfaction-of-search reduction in receiver operating characteristic experiments for detecting subtle test fractures with the addition of a major injury was not observed., Conclusions: Satisfaction of search was absent when major injuries were presented on radiographs. This finding rejects the hypothesis that SOS arises primarily from injuries requiring major intervention. Similar results have been found previously when major injuries were presented on CT but test fractures were presented on radiographs. This new finding rejects the possibility that SOS is absent because added and test fractures appear on different imaging modalities., (Copyright © 2012 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome is a distinct clinical entity representing involvement of the musculoskeletal and dermatologic systems. It is well known to rheumatologists because of characteristic skin manifestations and polyarthropathy. However, few reports exist in the orthopaedic literature. It is important to be aware of sAPHO syndrome as it can mimic some of the more common disease entities such as infection, tumor, and other inflammatory arthropathies. Anterior chest wall pain centered at sternoclavicular and sternocostal joints is an important and characteristic clinical finding which can point to its diagnosis. A patient may undergo different diagnostic tests and invasive procedures such as biopsies before a diagnosis is made. Imaging can be helpful by offering a detailed evaluation of the abnormalities. More importantly it helps in revealing subclinical foci of involvement due to the polyostotic nature of the disease. The treatment is mostly nonsurgical. NSAIDS are the first line agents. However multiple new agents are being used for refractory cases. Surgery is reserved to treat complications.

Objectives: To introduce a comprehensive and reliable scoring system for the assessment of whole-knee joint synovitis based on contrast-enhanced (CE) MRI., Methods: Multicenter Osteoarthritis Study (MOST) is a cohort study of people with, or at high risk of, knee osteoarthritis (OA). Subjects are an unselected subset of MOST who volunteered for CE-MRI. Synovitis was assessed at 11 sites of the joint. Synovial thickness was scored semiquantitatively: grade 0 (<2 mm), grade 1 (2-4 mm) and grade 2 (>4 mm) at each site. Two musculoskeletal radiologists performed the readings and inter- and intrareader reliability was evaluated. Whole-knee synovitis was assessed by summing the scores from all sites. The association of Western Ontario and McMaster Osteoarthritis Index pain score with this summed score and with the maximum synovitis grade for each site was assessed., Results: 400 subjects were included (mean age 58.8±7.0 years, body mass index 29.5±4.9 kg/m(2), 46% women). For individual sites, intrareader reliability (weighted κ) was 0.67-1.00 for reader 1 and 0.60-1.00 for reader 2. Inter-reader agreement (κ) was 0.67-0.92. For the summed synovitis scores, intrareader reliability (intraclass correlation coefficient ( ICC)) was 0.98 and 0.96 for each reader and inter-reader agreement (ICC) was 0.94. Moderate to severe synovitis in the parapatellar subregion was associated with the higher maximum pain score (adjusted OR (95% CI), 2.8 (1.4 to 5.4) and 3.1 (1.2 to 7.9), respectively)., Conclusions: A comprehensive semiquantitative scoring system for the assessment of whole-knee synovitis is proposed. It is reliable and identifies knees with pain, and thus is a potentially powerful tool for synovitis assessment in epidemiological OA studies.

Infectious spondylodiscitis is an uncommon disease with increasing incidence that typically presents with abnormalities in two adjacent vertebral bodies and the intervening disk. We describe two cases that initially presented with imaging abnormalities in only a single vertebral body. Both patients had a history of lumbar back pain and elevated inflammatory markers, but the lack of classical spondylodiscitis imaging findings led to diagnostic delay and confusion. It is likely that the incidence of atypical presentations of spondylodiscitis will increase as the disease incidence increases and imaging is performed at an earlier stage. It is important to recognize the disease early because early diagnosis is the key to preventing serious complications like epidural abscess and spinal cord compression.

Purpose: To assess the association of prevalent bone marrow edema-like lesions (BMLs) and full-thickness cartilage loss with incident subchondral cyst-like lesions (SCs) in the knee to evaluate the bone contusion versus synovial fluid intrusion theories of SC formation., Materials and Methods: The Multicenter Osteoarthritis study is a longitudinal study of individuals who have or are at risk for knee osteoarthritis. The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all participants. Magnetic resonance images were acquired at baseline and 30-month follow-up and read semiquantitatively by using the Whole-Organ Magnetic Resonance Imaging Score system. The tibiofemoral and patellofemoral joints were subdivided into 14 subregions. BMLs and SCs were scored from 0 to 3. Cartilage morphology was scored from 0 to 6. The association of prevalent BMLs and full-thickness cartilage loss with incident SCs in the same subregion was assessed by using logistic regression with mutual adjustment for both predictors., Results: A total of 1283 knees were included. After adjustment for full-thickness cartilage loss, prevalent BMLs showed a strong and significant association with incident SCs in the same subregion, with an odds ratio of 12.9 (95% confidence interval [CI]: 8.9, 18.6). After adjustment for BMLs, prevalent full-thickness cartilage loss showed a significant but much less important association with incident SCs in the same subregion (odds ratio, 1.4; 95% CI: 1.0, 2.0). There was no apparent relationship between severity of full-thickness cartilage loss at baseline and incident SCs., Conclusion: Prevalent BMLs strongly predict incident SCs in the same subregion, even after adjustment for full-thickness cartilage loss, which supports the bone contusion theory of SC formation., ((c) RSNA, 2010.)

Facet joint septic arthritis is a rare but severe infection with the possibility of significant morbidity resulting from local or systemic spread of the infection. Pain is the most common complaint on presentation followed by fever, then neurologic impairment. While the lumbar spine is involved in the vast majority of cases presented in the literature, the case presented here occurred in the cervical spine. The patient presented with a three week history of neck and left shoulder pain and was diagnosed by MRI when his pain did not respond to analgesics and muscle relaxants. The only predisposing factor was a history of diabetes mellitus and the infection most likely resulted from hematogenous spread. MRI is highly sensitive in diagnosing septic arthritis and it is the preferred modality for demonstrating the extent of infection and secondary complications including epidural and paraspinal abscesses as seen in this case. Without familiarity with this entity's predisposing factors, clinical symptoms and appropriate lab/imaging work up, many patients experience a delay in diagnosis. Treatment involves long term parenteral antibiotics or percutaneous drainage. Surgical debridement is reserved for cases with severe neurologic impairment. The incidence of facet joint septic arthritis is increasing likely related to patient factors (increasing number of patients >50 yo, immunosuppressed patients, etc), advancement in imaging technology, availability of MRI, and heightened awareness of this rare infection which is the aim of this case presentation.

Background: CT-guided biopsy is a minimally invasive diagnostic method of evaluating musculoskeletal lesions. Other options include incisional and excisional biopsy with the possibility of intraoperative frozen section. The clinician's decision to order a CT-guided biopsy requires an understanding of the likelihood that this biopsy will affect treatment This requires an understanding of both diagnostic yield and accuracy. Furthermore, the clinical utility of a biopsy is affected by factors other than the yield and accuracy as the clinical setting may render a technically diagnostic biopsy unhelpful., Methods: A retrospective review of the electronic record at an orthopedic oncology referral center identified all patients who had undergone CT-guided percutaneous needle biopsy of musculoskeletal lesions after being evaluated by an orthopedic oncologist in clinic over a period of 5 years. 53 CT-guided biopsies of bone lesions and 16 CT-guided biopsies of soft tissue lesions were identified. The diagnostic yield (rate of obtaining tissue from which the pathologist could report a diagnosis) and clinical utility (rate at which biopsy results guided treatment decisions) were calculated and statistically compared., Results: The overall diagnostic yield of CT-guided bone biopsies was 94% (50 of 53 biopsies) and the clinical utility was 70% (37 of 53 biopsies). In the first 2 years of the study the diagnostic yield was 95% (21 of 22 biopsies) and the clinical utility was 86% (19 of 22 biopsies). In the remaining 3 years the diagnostic yield was 91% (28 of 31 biopsies) and the clinical utility was 58% (18 of 31 biopsies). This decrease in clinical utility over time was statistically significant (p = 0.01). Suspicion of metastasis resulted in a diagnostic yield of 100% (11/11) and a clinical utility of 91% (10/11). Suspicion of primary tumor resulted in a diagnostic yield and clinical utility of 93% (39/42) and 67% (28/42), respectively. This difference in clinical utility was statistically significant (p = 0.02). The diagnostic yield of CT-guided soft tissue biopsies was 75% (12 of 16 biopsies) and the clinical utility was 69% (11 of 16 biopsies). The diagnostic yield was significantly lower for soft tissue biopsy than bone biopsy (p = 0.01). There was no relationship between the rate of diagnostic biopsies and the evaluating pathologist or the location of the lesion within the body., Conclusions: CT-guided biopsy is useful in the diagnosis of musculoskeletal lesions, however, its clinical utility is substantially lower than its diagnostic accuracy and yield due to a significant rate of diagnostic biopsies that fail to guide treatment, particularly when a primary lesion is suspected. The disparity in clinical utility based on preoperative suspicion of metastasis was even greater in our study than previously shown. CT-guided percutaneous needle biopsy is much more likely to guide treatment in the setting of suspected bone metastasis as opposed to biopsies of suspected primary bone lesions and soft tissue lesions.

Purpose: To assess baseline factors that may predict fast tibiofemoral cartilage loss over a 30-month period., Materials and Methods: The Multicenter Osteoarthritis (MOST) study is a longitudinal study of individuals who have or who are at high risk for knee osteoarthritis. The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all participants. Magnetic resonance (MR) images were read according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) system. Only knees with minimal baseline cartilage damage (WORMS < or = 2.5) were included. Fast cartilage loss was defined as a WORMS of at least 5 (large full-thickness loss, less than 75% of the subregion) in any subregion at 30-month follow-up. The relationships of age, sex, body mass index (BMI), ethnicity, knee alignment, and several MR features (eg, bone marrow lesions, meniscal damage and extrusion, and synovitis or effusion) to the risk of fast cartilage loss were assessed by using a multivariable logistic regression model., Results: Of 347 knees, 90 (25.9%) exhibited cartilage loss, and only 20 (5.8%) showed fast cartilage loss. Strong predictors of fast cartilage loss were high BMI (adjusted odds ratio [OR], 1.11; 95% confidence interval [CI]: 1.01, 1.23), the presence of meniscal tears (adjusted OR, 3.19; 95% CI: 1.13, 9.03), meniscal extrusion (adjusted OR, 3.62; 95% CI: 1.34, 9.82), synovitis or effusion (adjusted OR, 3.36; 95% CI: 0.91, 12.4), and any high-grade MR-depicted feature (adjusted OR, 8.99; 95% CI: 3.23, 25.1)., Conclusion: In participants with minimal baseline cartilage damage, the presence of high BMI, meniscal damage, synovitis or effusion, or any severe baseline MR-depicted lesions was strongly associated with an increased risk of fast cartilage loss. Patients with these risk factors may be ideal subjects for preventative or treatment trials.

This article discusses the indications for CT in the management of acute fractures and postoperative complications related to orthopedic procedures. The current clinical use of CT in spine injuries, pelvic/acetabular fractures, and major fractures in the extremities is discussed. Multidetector CT techniques to minimize metal artifacts and common hardware complications are reviewed.

A single fracture of the ring of a vertebra is a rare injury of the spine. In this report, we present five single fractures of the posterior ring of the cervical spine below the atlas from four patients after motor vehicle accidents. Initial radiographs failed to show any of these fractures; all were detected by computed tomography. Single ring fractures are stable and none of our patients presented with a neurological deficit. Patients were treated conservatively with a cervical collar or a cervicothoracic brace. They all recovered without any neurological abnormalities.

Acetabular fractures are often complex injuries and the result of high-energy trauma with associated injuries. Understanding and classification of these rare injuries using radiography can be difficult and are much facilitated by the addition of computed tomography (CT). The purpose of this paper is to briefly review some of the underlying physical principles and technical factors for multidetector CT (MDCT) and to describe its use and imaging findings in the evaluation of acetabular fractures. Using MDCT with two-dimensional multiplanar reformatted (MPR) images and three-dimensional volume rendered images, the supplemental oblique radiographic Judet views can be omitted. MDCT is now an indispensable tool in preoperative imaging of acetabular fractures and also in postoperative imaging in complicated cases. Not only is MDCT excellent for a general overview but also for detailed imaging of fracture extent, joint congruency, step-offs or gaps in the joint surface, and entrapped osteochondral fragments.

Chronic foot pain is a common and often disabling clinical complaint that can interfere with a patient's routine activities. Despite careful and detailed clinical history and physical examination, providing an accurate diagnosis is often difficult because chronic foot pain has a broad spectrum of potential causes. Therefore, imaging studies play a key role in diagnosis and management. Initial assessment is typically done by plain radiography; however, magnetic resonance imaging has superior soft-tissue contrast resolution and multiplanar capability, which makes it important in the early diagnosis of ambiguous or clinically equivocal cases when initial radiographic findings are inconclusive. Computed tomography displays bony detail in stress fractures, as well as in arthritides and tarsal coalition. Bone scanning and ultrasonography also are useful tools for diagnosing specific conditions that produce chronic foot pain.

We present a sleeve fracture at the superior pole of the patella in a 12-year-old boy. Sleeve fractures at the inferior pole of the patella have been well described in the orthopedic and radiologic literature. However, a similar injury at the superior pole of the patella is relatively rare. We hope that awareness of this unusual injury and its imaging findings will allow timely diagnosis and intervention.

Atlas fractures commonly present more than two breaks in its ring structure because of the unique anatomy and the mechanism of injury. The incidence of a single break in the atlas ring is exceedingly rare. However, we encountered two cases of a single fracture of the atlas. One patient was struck by a falling tree on the right side of the head and the other was involved in a motor vehicle accident. Radiographs of the cervical spine failed to show a single fracture or other abnormalities. Computed tomography demonstrated the single fracture. The patients were treated conservatively with a cervical collar, and they both recovered completely. In this article, we present two cases of a single fracture of the atlas with a review of the literature.

Cervical spine injuries of children, though rare, have a high morbidity and mortality. The pediatric cervical spine is anatomically and biomechanically different from that of adults. Hence, the type, level and outcome of cervical spine injuries in children are different from those seen in adults. Normal developmental variants seen in children can make evaluation of the pediatric cervical spine challenging. This article reviews the epidemiology of pediatric cervical spine trauma, normal variants seen in children and specific injuries that are more common in the pediatric population. We also propose an evidence-based imaging protocol to avoid unnecessary imaging studies and minimize radiation exposure in children.

Rationale and Objectives: Satisfaction of search (SOS) occurs when an abnormality is missed because another abnormality has been detected. This research studied whether the severity of a detected fracture determines whether subsequent fractures are overlooked., Materials and Methods: Each of 70 simulated multitrauma patients presented examinations of three anatomic areas. Readers evaluated each patient under two experimental conditions: when the images of the first anatomic area included a fracture (the SOS condition), and when it did not (the control condition). The SOS effect was measured on detection accuracy for subtle test fractures presented on examinations of the second and third anatomic areas. In an experiment with 12 radiology readers, the initial SOS radiographs showed nondisplaced fractures of extremities, fractures associated with low morbidity. In another experiment with 12 different radiology readers, the initial examination, usually a computed tomography scan, showed cervical and pelvic fractures of the type associated with high morbidity. Because of their more direct role in patient care, the experiment using high morbidity SOS fractures was repeated with 17 orthopedic readers., Results: Detection of subtle test fractures was substantially reduced when fractures of low morbidity were added (P < .01). No similar SOS effect was observed in either experiment in which added fractures were associated with high morbidity., Conclusions: The satisfaction of search effect in skeletal radiology was replicated, essentially doubling the evidence for SOS in musculoskeletal radiology, and providing an essential contrast to the absence of SOS from high-morbidity fractures.

The unique ability of magnetic resonance (MR) imaging to visualize injuries of bone, cartilage, bone marrow, and supporting soft tissue structure makes it ideally suited for the evaluation of musculoskeletal trauma. Magnetic resonance imaging also offers exquisitely detailed anatomical information on the musculoskeletal system. The widespread availability of MR imaging and the constantly improving technology make it the imaging modality of choice for the patients with a musculoskeletal trauma. This review discusses the role and applications of MR imaging for musculoskeletal trauma. It covers traumatic conditions of the musculoskeletal system, including hemarthrosis, lipohemarthrosis, stress fracture, occult fractures, cartilage injuries, the muscle and tendon trauma, avulsion injuries, extensor mechanism injuries, and traumatic conditions of joints.

Recent advances in cross-sectional imaging, particularly in CT and MR imaging, have given these modalities a prominent role in the diagnosis of fractures of the extremities. This article describes the clinical application and imaging features of cross-sectional imaging (CT and MR imaging) in the evaluation of patients who have occult fractures of the extremities. Although CT or MR imaging is not typically required for evaluation of acute fractures, these modalities could be helpful in the evaluation of the occult osseous injuries in which radiographic findings are equivocal or inconclusive.

Two adult patients are described with multifocal osteolytic lesions radiologically simulating a vascular tumor. One patient had multiple bones involved. Histologically, the individual lesions had the features of the nidus of osteoid osteoma/osteoblastoma. A review of the English language medical literature yielded only one other reported case with similar features. The process is designated as osteoblastomatosis to indicate its bone-forming character, prominent osteoblast proliferation, and multiplicity. The cases are distinguished from multifocal/multicentric osteoid osteoma and osteoblastoma, and from benign and malignant vascular tumors.