Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Ex Input:
Abstract: Two cases of osteochondritis dissecans of the talar dome treated by closed percutaneous drilling are presented to illustrate a procedure for high-risk patients. The operation is performed with the aid of an image intensifier. The ostoechondral fragment is percutaneously drilled to avoid open operation and osteotomizing the medial malleolus.

Ex Output:
Adolescence

Ex Input:
Abstract: Pillars of calcification are rarely found in the skin. An interesting case is described where rows of new bone developed in the skin which had been grafted 31 years previously to cover partial skin thickness burns of the shin. The problems of heterotropic ossification are discussed.

Ex Output:
Adult

Ex Input:
Abstract: Paired maternal and umbilical vein blood samples were obtained from 15 women and the plasma antithrombin III activity and fibrinopeptide A concentration measured. Women with preeclampsia had significantly lower antithrombin III activities and higher fibrinopeptide A concentrations (P less than .05) than normals. However, there were no significant differences between the two groups of fetuses. Thus, thrombin generation was not increased in the fetuses delivered from preeclamptic women.

Ex Output:
Antithrombin III