Imaging of osteoarthritis from the ankle through the midfoot.

Ankle, hindfoot, and midfoot osteoarthritis (OA) is most commonly posttraumatic and tends to become symptomatic in younger patients. It often results from instability due to insufficiency of supportive soft tissue structures, such as ligaments and tendons. Diagnostic imaging can be helpful to detect and characterize the distribution of OA, and to assess the integrity of these supportive structures, which helps determine prognosis and guide treatment. However, the imaging findings associated with OA and instability may be subtle and unrecognized until the process is advanced, which may ultimately limit therapeutic options to salvage procedures. It is important to understand the abilities and limitations of various imaging modalities used to assess ankle, hindfoot, and midfoot OA, and to be familiar with the imaging findings of OA and instability patterns.

Magnetic resonance imaging of musculoskeletal infections.

Magnetic resonance imaging (MRI) is a powerful imaging modality in the evaluation of musculoskeletal (MSK) soft tissue, joint, and bone infections. It allows prompt diagnosis and assessment of the extent of disease, which permits timely treatment to optimize long-term clinical outcomes. MRI is highly sensitive and specific in detecting the common findings of MSK infections, such as superficial and deep soft tissue oedema, joint, bursal and tendon sheath effusions, lymphadenopathy, bone marrow oedema, erosive bone changes and periostitis, and bone and cartilage destruction and sequestration. Contrast-enhanced MRI allows detection of non-enhancing fluid collections and necrotic tissues, rim-enhancing abscesses, heterogeneously or diffusely enhancing phlegmons, and enhancing active synovitis. Diffusion-weighted imaging (DWI) is useful in detecting soft-tissue abscesses, particularly in patients who cannot receive gadolinium-based intravenous contrast. MRI is less sensitive than computed tomography (CT) in detecting soft-tissue gas. This article describes the pathophysiology of pyogenic MSK infections, including the route of contamination and common causative organisms, typical MR imaging findings of various soft tissue infections including cellulitis, superficial and deep fasciitis and necrotizing fasciitis, pyomyositis, infectious bursitis, infectious tenosynovitis, and infectious lymphadenitis, and of joint and bone infections including septic arthritis and osteomyelitis (acute, subacute, and chronic). The authors also discuss MRI findings and pitfalls related to infected hardware and diabetic foot infections, and briefly review standards of treatment of various pyogenic MSK infections.

Transphyseal involvement of pyogenic osteomyelitis is considerably more common than classically taught.

OBJECTIVE: Radiologists are taught that pyogenic osteomyelitis in children rarely crosses the growth plate because terminal vessels of nutrient arteries loop at the physis, predisposing the metaphysis to hematogenous infection. However, we note that MRI frequently shows osteomyelitis involving both sides of the physis. The purpose of this article is to document our observation that pyogenic osteomyelitis crosses the growth plate more frequently in the pediatric patient population than is classically taught. MATERIALS AND METHODS: All pediatric patients (age, 2-16 years) with clinically suspected osteomyelitis from 2004 to 2009 were reviewed for transphyseal disease on a consensus basis. To reveal the statistical significance, we applied a z test to our results. We quantified rare as 20% or less and used a z test to determine whether 27 of 32 (81%) differed from rare. RESULTS: Of 32 subjects, 81% showed transphyseal infection. In our study, the z test revealed that transphyseal infection occurred significantly more often than what would be considered rare (z = 4.75, p < 0.01). CONCLUSION: In our pediatric patient population, we have documented a higher frequency of transphyseal osteomyelitis (81%) than metaphyseal osteomyelitis in pyogenic infections. When our findings are statistically compared with an expected rate of 20%, they cannot be attributed to chance alone. This raises some doubt regarding the conventional understanding of pediatric pyogenic osteomyelitis.

Hypothenar hammer syndrome: Case report and literature review.

Hypothenar hammer syndrome is a rare but serious cause of digital ischemia and morbidity. Presented here is a case of a manual laborer who had symptoms of digital ischemia after acute hyperextension injury to the ring finger. Magnetic resonance imaging revealed thrombosed ulnar artery aneurysm. Etiology, presentation, and current treatments are reviewed.