Cartilage injury after acute, isolated anterior cruciate ligament tear: immediate and longitudinal effect with clinical/MRI follow-up.

BACKGROUND: Anterior cruciate ligament (ACL) tears have been implicated in the development of osteoarthritis. Limited data exist on longitudinal follow-up of isolated ACL injury. HYPOTHESES: All isolated ACL tears are associated with some degree of cartilage injury that will deteriorate over time. There is a threshold of magnetic resonance imaging (MRI)-detectable cartilage injury that will correlate with adverse change in subjective patient-reported outcome measures. STUDY DESIGN: Cohort study, Level of evidence, 2. METHODS: The authors conducted a prospective, observational analysis of 42 knees in 40 patients with acute, isolated ACL injury (14 treated nonoperatively, 28 by reconstruction) with imaging at the time of injury and yearly follow-up for a maximum of 11 years. Morphologic MRI and quantitative T2 mapping was performed with validated outcome measures. RESULTS: All patients sustained chondral damage at initial injury. The adjusted risk of cartilage loss doubled from year 1 for the lateral compartment and medial femoral condyle (MFC) and tripled for the patella. By years 7 to 11, the risk for the lateral femoral condyle was 50 times baseline, 30 times for the patella, and 19 times for the MFC. There was increased risk of cartilage degeneration over the medial tibial plateau (MTP) (P = .047; odds ratio = 6.23; 95% confidence interval [CI], 1.03-37.90) and patella (P = .032; odds ratio = 4.88; 95% CI, 1.14-20.80) in nonsurgical patients compared with surgically treated patients. Size of the bone-marrow edema pattern was associated with cartilage degeneration from baseline to year 3 (P = .001 to .039). Each increase in the MFC Outerbridge score resulted in a 13-point decrease in the International Knee Documentation Committee subjective knee score (P = .0002). Each increase in the MTP resulted in a 2.4-point decrease in the activity rating scale (P = .002). CONCLUSION: All patients with acute, traumatic ACL disruption sustained a chondral injury at the time of initial impact with subsequent longitudinal chondral degradation in compartments unaffected by the initial "bone bruise," a process that is accelerated at 5 to 7 years' follow-up.

Cartilage imaging in sports medicine.

Magnetic resonance imaging (MRI) using cartilage-sensitive sequences has been shown to be an accurate, noninvasive method by which to detect articular cartilage injury and early degeneration. These are important management considerations in an athletic population. The advantages of MRI include the lack of ionizing radiation, direct multiplanar capabilities and high-contrast resolution of articular soft tissue structures. The present review details imaging strategies for assessing cartilage in the athletic population, defines the normal MRI appearance of articular cartilage, and illustrates the spectrum of articular cartilage lesions seen in various joints of the body.

New techniques in articular cartilage imaging.

Standardized magnetic resonance imaging (MRI) pulse sequences provide an accurate, reproducible assessment of cartilage morphology. Three-dimensional (3D) modeling techniques enable semiautomated models of the joint surface and thickness measurements, which may eventually prove essential in templating before partial or total joint resurfacing as well as focal cartilage repair. Quantitative MRI techniques, such as T2 mapping, T1 rho, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), provide noninvasive information about cartilage and repair tissue biochemistry. Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) demonstrate information regarding the regional anisotropic variation of cartilage ultrastructure. Further research strengthening the association between quantitative MRI and cartilage material properties may predict the functional capacity of native and repaired tissue. MRI provides an essential objective assessment of cartilage regenerative procedures.

Intracranial pyogenic abscess: imaging diagnosis utilizing recent advances in computed tomography and magnetic resonance imaging.

Intracranial abscesses are life-threatening medical emergencies with pyogenic debris accumulating in the brain. Delay in the diagnosis can result in significant morbidity and mortality. Computed tomography and magnetic resonance imaging play an important role in the diagnosis of brain abscesses. However, the classic ring-enhancing appearance of an intracranial abscess can be mimicked by several other entities, most notably a necrotic tumor. This paper reviews new advances in CT and MR for imaging patients with suspected brain abscess. The role of computed tomography (CT) perfusion and new magnetic resonance sequences including DWI sequences, ADC map, MR spectroscopy, FLAIR and post-contrast enhanced T1 weighted images will also be discussed.