Intraosseous lipomas originating from simple bone cysts.

PURPOSE: Fatty or part-fatty intraosseous lesions are occasionally encountered while imaging the skeletal system. A number of case reports have proposed involution of calcaneal bone cysts to intraosseous lipomas, but this has never been proven. This paper sets out to prove that simple bone cysts (SBCs) can involute to fatty lesions indistinguishable from intraosseous lipomas. MATERIALS AND METHODS: The pathology and PACS databases at 2 specialist orthopedic hospitals were retrospectively interrogated for all cases of intraosseous lipomas or SBCs with cross-sectional imaging follow-up for SBCs and precursor or follow-up imaging for intraosseous lipomas, in the time period from August 2007 to December 2016. For intraosseous lipoma cases, these were only included if change in imaging appearances was observed. RESULTS: There was no case of change in the appearance in intraosseous lipomas. Six cases of SBC with cross-sectional imaging follow-up were identified in one participating hospital and none in the other. The 6 cases were comprised of 4 male and 2 female patients. Two were located in the proximal humerus, one in the proximal tibia, and 3 in the os calcis. All cases demonstrated filling in of the cystic lesion with fat from the periphery, in 2 cases complete filling in, and in 4 cases partial fatty conversion. CONCLUSION: SBCs can heal with fatty conversion of the cystic cavity, with partly cystic remnants. It is proposed that at least part of the so-called intraosseous lipomas are healed simple bone cysts.

Stress Injuries of the Spine in Sports.

Spine sports stress injuries account for a significant amount of time loss at play in athletes, particularly if left unrecognized and allowed to progress. Spondylolysis makes up most of these stress injuries. This article focuses on spondylolysis, bringing together discussion from the literature on its pathomechanics and the different imaging modalities used in its diagnosis. Radiologists should be aware of the limitations and more importantly the roles of different imaging modalities in guiding and dictating the management of spondylolysis. Other stress-related injuries in the spine are also discussed including but not limited to pedicle fracture and apophyseal ring injury.

Correction to: Consensus document for the diagnosis of prosthetic joint infections: a joint paper by the EANM, EBJIS, and ESR (with ESCMID endorsement).

The authors regret to inform the readers that one of the author's name in the original publication of this article was spelled incorrectly as Victor Casar-Pullicino. The correct spelling is Victor N. Cassar-Pullicino and is now presented correctly in this article.

Multiple long bone cysts revealed by MRI in trichorhinophalangeal syndrome type II predisposing to pathological fractures.

Trichorhinophalangeal syndrome type II is a rare genetic disorder with the few published case reports mainly reporting the radiographic skeletal manifestations. There are no published imaging reports of long bone cysts involving multiple bones in this condition. We report a unique case of bone cysts involving multiple long bones detected with MRI in a patient with trichorhinophalangeal syndrome type II complicated by a subsequent pathological fracture. It is possible that the bone cysts are a previously undescribed feature of this syndrome; however, the evidence is insufficient to establish a definite association. Chromosomal abnormality identified in this patient is consistent with trichorhinophalangeal syndrome type II with no unusual features. Although the nature of these bone cysts is unclear, they are one of the causes of the known increased fracture risk observed in this syndrome.

Paget Disease of Bone.

Paget disease (PD) is a common disease of bone associated with abnormal bone turnover that in turn is due to an imbalance between osteoclastic and osteoblastic activity. There is good evidence that PD is reducing in incidence, prevalence, and severity. The disease is most often asymptomatic and is usually detected incidentally on imaging examinations performed for other reasons. The features of PD are relatively specific on radiographs and computed tomography. However, the appearances on magnetic resonance imaging are subtle and nonspecific, although it has become the initial imaging choice for several clinical indications including back pain, neurologic dysfunction, and knee pain. It is therefore important to be familiar with the various imaging appearances of this relatively common disease in an increasingly aging population. In this article we discuss the various imaging appearances of PD and its complications.

Neuropathic osteoarthropathy with and without superimposed osteomyelitis in patients with a diabetic foot.

Soft tissue and bone infection involving the foot is one of the most common long-term complications of diabetes mellitus, implying a serious impairment in quality of life for patients in the advanced stages of the disease. Neuropathic osteoarthropathy often coexists and differentiating between these two entities is commonly challenging, but crucial, as the management may differ substantially. The importance of correct diagnosis cannot be understated and effective management requires a multidisciplinary approach owing to the complicated nature of therapy in such patients. A missed diagnosis has a high likelihood of major morbidity for the patient, including limb amputation, and over-diagnosis results in a great socioeconomic challenge for healthcare systems, the over-utilization of healthcare resources, and the unwise use of antibiotics. Diagnosis is largely based on clinical signs supplemented by various imaging modalities such as radiography, MR imaging, and hybrid imaging techniques such as F-18 fluorodeoxyglucose-positron emission tomography. In the interests of the management of diabetic foot complications, this review article is aimed on the one hand at providing radiologists with important clinical knowledge, and on the other hand to equip clinicians with relevant radiological semiotics.

The SAPHO syndrome revisited with an emphasis on spinal manifestations.

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome includes a group of chronic, relapsing, inflammatory musculoskeletal disorders with similar manifestations, in particular synovitis, hyperostosis, and osteitis, which may or may not be associated with neutrophilic skin eruptions such as palmoplantar pustulosis and acne conglobata. The syndrome occurs at any age, can involve any skeletal site, and its imaging appearances are variable, depending on the stage/age of the lesion and imaging method. The diagnosis is difficult if there is no skin disease. Awareness of the imaging appearances, especially in the spine, may help the radiologist in avoiding misdiagnosis (e.g., infection, tumor) and unnecessary invasive procedures, while facilitating early diagnosis and selection of an effective treatment. In this article, we provide an overview of the radiological appearances of SAPHO syndrome, focusing on the magnetic resonance imaging findings of vertebral involvement, and present relevant clinical and pathological features that assist early diagnosis.

Radiofrequency thermo-ablation of PVNS in the knee: initial results.

INTRODUCTION: Pigmented villonodular synovitis (PVNS) is normally treated by arthroscopic or open surgical excision. We present our initial experience with radiofrequency thermo-ablation (RF ablation) of PVNS located in an inaccessible location in the knee. MATERIALS: Review of all patients with histologically proven PVNS treated with RF ablation and with at least 2-year follow-up. RESULTS: Three patients met inclusion criteria and were treated with RF ablation. Two of the patients were treated successfully by one ablation procedure. One of the three patients had a recurrence which was also treated successfully by repeat RF ablation. There were no complications and all patients returned to their previous occupations following RF ablation. CONCLUSION: In this study we demonstrated the feasibility of performing RF ablation to treat PVNS in relatively inaccessible locations with curative intent. We have also discussed various post-ablation imaging appearances which can confound the assessment for residual/recurrent disease.

Image guided radiofrequency thermo-ablation therapy of chondroblastomas: should it replace surgery?

OBJECTIVE: To assess the safety and effectiveness of image-guided radiofrequency ablation (RF ablation) in the treatment of chondroblastomas as an alternative to surgery. MATERIALS AND METHODS: Twelve patients with histologically proven chondroblastoma at our institution from 2003 to date. We reviewed the indications, recurrences and complications in patients who underwent RF ablation. RESULTS: Twelve patients were diagnosed with chondroblastoma. Out of these, 8 patients (6 male, 2 female, mean age 17 years) with chondroblastoma (mean size 2.7 cm) underwent RF ablation. Multitine expandable electrodes were used in all patients. The number of probe positions needed varied from 1 to 4 and lesions were ablated at 90 °C for 5 min at each probe position. The tumours were successfully treated and all patients became asymptomatic. There were no recurrences. There were 2 patients with knee complications, 1 with minor asymptomatic infraction of the subchondral bone and a second patient with osteonecrosis/chondrolysis. CONCLUSION: Radiofrequency ablation appears to be a safe and effective alternative to surgical treatment with a low risk of recurrence and complications for most chondroblastomas. RF ablation is probably superior to surgery when chondroblastomas are small (less than 2.5 cm) with an intact bony margin with subchondral bone and in areas of difficult surgical access.

Prevalence of extraforaminal nerve root compression below lumbosacral transitional vertebrae.

OBJECTIVE: Although pathology at the first mobile segment above a lumbosacral transitional vertebra (LSTV) is a known source of spinal symptoms, nerve root compression below an LSTV, has only sporadically been reported. Our objective was to assess the prevalence of nerve root entrapment below an LSTV, review the causes of entrapment, and correlate with presenting symptoms. MATERIALS AND METHODS: A retrospective review of MR and CT examinations of the lumbar spine was performed over a 5.5-year period in which the words "transitional vertebra" were mentioned in the report. Nerve root compression below an LSTV was assessed as well as the subtype of transitional vertebra. Correlation with clinical symptoms at referral was made. MR and CT examinations were also reviewed to exclude any other cause of symptoms above the LSTV. RESULTS: One hundred seventy-four patients were included in the study. Neural compression by new bone formation below an LSTV was demonstrated in 23 patients (13%). In all of these patients, there was a pseudarthrosis present on the side of compression due to partial sacralization with incomplete fusion. In three of these patients (13%), there was symptomatic correlation with no other cause of radiculopathy demonstrated. A further 13 patients (57%) had correlating symptoms that may in part be attributable to compression below an LSTV. CONCLUSIONS: Nerve root compression below an LSTV occurs with a prevalence of 13% and can be symptomatic in up to 70% of these patients. This region should therefore be carefully assessed in all symptomatic patients with an LSTV.

Subchondral impaction fractures of the non-weight-bearing portion of the lateral femoral condyle.

OBJECTIVE: To document the first report of intra-articular, non-weight-bearing, impaction fractures of the lateral femoral condyle. MATERIALS & METHODS: Institutional Review Board and Regional Ethics Committee approval for this study was obtained and patient informed consent deemed unnecessary. We prospectively documented all potential cases of non-weight-bearing posterior subchondral impaction fractures of the femoral condyles diagnosed on magnetic resonance imaging (MRI) of the knee performed at our institution between January 2006 and December 2011. The cases were reviewed and discussed by three experienced musculoskeletal radiologists and only cases satisfying pre-defined MRI criteria were included. RESULTS: Sixteen cases of intra-articular impaction fractures in a posterior, non-weight-bearing area of the lateral femoral condyle were diagnosed in patients with a mean age of 40. Eight were associated with recreational sports activities and 4 with repeated kneeling. There were no fractures documented in the non-weight-bearing aspect of the medial femoral condyles. Proposed underlying mechanisms for development of this type of fracture are presented. CONCLUSION: Awareness, along with a high level of suspicion, that non-specific knee pain, especially in patients involved in athletic activities, could be due to intra-articular impaction fractures of the non-weight-bearing posterior aspect of the lateral femoral condyle is essential and MRI is the mainstay of diagnosis.

Venous air embolism in consecutive balloon kyphoplasties visualised on CT imaging.

OBJECTIVE: We noted a large amount of intravenous gas during balloon kyphoplasty on CT imaging. Formal assessment to understand the extent, possible causes and implications was undertaken. MATERIALS AND METHODS: Ten consecutive cases of balloon kyphoplasty were performed under general anaesthesia in the prone position, on a single vertebral level using a two-step technique under combined fluoroscopic and CT guidance. CT of the affected vertebra was performed before, after, and intermittently during the procedure. In 2 cases delayed CT was carried out in the supine position. RESULTS: Gas was seen on CT imaging, but not on conventional fluoroscopy. The gas is most likely to be air introduced during the procedure and was seen in the epidural and paravertebral venous plexus, posterior intercostal veins, renal veins, IVC and azygos vein. The average measured volume of gas seen on the post-procedure CT imaging was 1.07 mL, range 0.16-3.97 mL. There was no correlation of the measured amount of gas to the procedure duration or location, the use of a curette or the injected cement volume. Delayed CT in the supine position no longer showed air in the local venous system. CONCLUSIONS: Balloon kyphoplasty is associated with the fluoroscopically invisible introduction of air into the vertebral and paravertebral veins and deep systemic veins and is likely to be much more extensive than identified on CT imaging. There is potential for serious air embolism in kyphoplasty and if there is a sudden deterioration in patient condition during the procedure the possibility of this complication needs to be considered.

Entrapped intralesional marrow: a hitherto undescribed imaging feature of benign notochordal cell tumour.

We report two cases of histologically proven benign notochordal cell tumour (BNCT) with imaging evidence of entrapped intralesional marrow and discuss the relevance of previously undescribed imaging feature.

Ossicles of lumbar articular facets: normal variant or spondylolytic variant?

PURPOSE: The objective of this study was to establish the prevalence and significance of ossicles of lumbar articular facets (OLAF) in young athletes with backache diagnosed by multi-detector computed tomography (MDCT). MATERIALS AND METHODS: The MDCT examinations of the lumbar spine carried out for suspected spondylolysis on 46 consecutive symptomatic young athletes presenting to a sports injury clinic over a 1-year period were retrospectively reviewed. OLAF study included detailed correlation with the structural and morphological stress features of the posterior neural arches. This was then compared with a control group composed of 39 patients. RESULTS: Twenty-three OLAF were identified in 15 patients. Eleven of the 15 patients with ossicles had posterior element stress changes (PEST)/pars defects. In the control group, two OLAF were identified in two patients, one demonstrating PEST changes. CONCLUSION: The high prevalence of OLAF in young symptomatic athletes compared with the asymptomatic control group is indicative of stress fractures. The non-united articular process fractures should be regarded as part of the spectrum of stress-induced changes in the posterior neural arch in the same way as spondylolysis. MDCT with volumetric acquisition and multi-planar reformation is the most reliable investigation in the diagnosis of OLAF. KEY POINTS: 1) This CT study supports a traumatic aetiology for lumbar articular facets ossicles. 2) OLAF represent part of a spectrum of stress-induced changes in the posterior neural arch. 3) OLAF are associated with typical spondylolysis. 4) OLAF can be overlooked on reverse gantry angle computed tomography (RG-CT). 5) OLAF may account for some of the discrepancy between radionuclide and RG-CT studies.

Predictors of fracture healing in patients with recalcitrant nonunions treated with autologous culture expanded bone marrow-derived mesenchymal stromal cells.

The study reports the prospective outcome of treating severe recalcitrant fracture nonunion in patients with autologous bone marrow-derived mesenchymal stromal cells (BMSC) from 2003 to 2010 and analyze predictors of union. Autologous BMSC were culture expanded and inserted at nonunion site with or without carriers in addition to surgical stabilization of the fracture. Radiological union was ascertained by musculoskeletal radiologists on plain radiographs and/or CT scans. A logistic regression analysis was performed with cell-expansion parameters (cell numbers, cell doubling time) and known clinical factors (e.g., smoking and diabetes) as independent variables and fracture union as the dependent variable to identify the factors that influence bony healing. An Eq5D index score assessed the effect of treatment on general quality of health. A total of 35 patients (mean age 51+/-13 years) with established nonunion (median 2.9 years, 1-33) and, at least one failed nonunion surgery (median 4,1-14) received treatment. Fracture union was achieved in 21 patients (60%; 95%CI 44-75) at 2.6 years. Multiple penalized logistic regression revealed faster cell doubling time (p = 0.07), absence of diabetes (p = 0.003), less previous surgeries (p = 0.008), and lower age at cell implantation (p = 0.02) were significant predictors for fracture union. A significant increase in Eq5D index (p = 0.01) was noted with a mean rise of the score by 0.34 units (95%CI 0.11-0.58) at 1 year following the study. In summary, the study revealed cell doubling time as a novel in vitro parameter in conjunction with age, multiple surgeries, and diabetes as being significant predictors of the fracture union. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 37:1303-1309, 2019.

Magnetic resonance imaging of appendicular musculoskeletal infection.

Appendicular skeletal infection includes osseous and extraosseous infections. Skeletal infection needs early diagnosis and appropriate management to prevent long-term morbidity. Magnetic resonance imaging is the best imaging modality to diagnose skeletal infection early in most circumstances. This article describes the role of magnetic resonance imaging in relation to the other available imaging modalities in the diagnosis of skeletal infection. Special circumstances such as diabetic foot, postoperative infection, and chronic recurrent multifocal osteomyelitis are discussed separately.

Magnetic resonance imaging of spinal infection.

This article reviews the pathophysiology of spinal infection and its relevance for imaging. Magnetic resonance imaging (MRI) is the modality with by far the best sensitivity and specificity for spinal infection. The imaging appearances of spinal infection in MRI are outlined, and imaging techniques are discussed. The problems of clinical diagnosis are outlined. There is some emphasis on the MRI differentiation of pyogenic and nonpyogenic infection and on the differential diagnosis of spinal infection centered on the imaging presentation.