Magnetic resonance imaging of the knee.

Magnetic resonance imaging (MRI) has revolutionised diagnostic imaging of the knee. It has evolved significantly since Kean described healthy and pathologic knee anatomy in 1983. This innovative technology allows superior soft-tissue detail with multiplanar imaging capability that provides accurate evaluation of intra- and extra-articular structures of the knee not demonstrated with other imaging modalities. The development and advancements in MRI and the introduction of high-resolution coils have provided a noninvasive, nonoperator dependent, cost effective means to diagnose knee pathology. MRI is well tolerated by patients, widely accepted by evaluating physicians, and assists in distinguishing pathologic knee conditions that may have similar clinical signs and symptoms (i.e. meniscal tears, osteochondral lesions). This paper presents an overview of MRI of the knee and focuses on the MRI findings in a number of common pathologic conditions.

Ability of chronic wound fluids to degrade peptide growth factors is associated with increased levels of elastase activity and diminished levels of proteinase inhibitors.

The stability of peptide growth factors exposed to fluids from healing surgical wounds and from nonhealing chronic wounds was examined in vitro. (125)I-Labeled transforming growth factor-beta1 or platelet-derived growth factor-BB was incubated with fluids from healing surgical wounds and fluids from venous stasis or pressure ulcers. Fluids from healing surgical wounds had no appreciable effect on the level of (125)I corresponding to intact growth factor. In contrast, incubation with fluids from several venous stasis or pressure ulcers resulted in significant degradation of these growth factors. Degradation was blocked by broad-spectrum serine proteinase inhibitors and by specific inhibitors of neutrophil elastase. Levels of elastase activity in wound fluids correlated with the ability to degrade peptide growth factors. Further comparisons showed qualitative and quantitative differences in the endogenous proteinase inhibitors, alpha2-macroglobulin and alpha1-antiproteinase. These results could explain, in part, the variable growth factor levels which have been found in chronic wounds. More importantly, the ability of some chronic nonhealing wounds to rapidly degrade exogenously added growth factors has important implications with regard to past and future clinical attempts to use peptide growth factors to treat these types of problem wounds.