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.

Input: Consider Input: Abstract: Twenty patients were examined by standard radiography and roentgen stereophotogrammetric analysis (RSA) during a two-year period after total hip arthroplasty. Eleven of the acetabular components migrated cranially and three femoral components migrated distally. This migration was most rapid during the first four months after operation. Our findings support the possibility that mechanical loosening is initiated by thermal injury during polymerisation of the cement; the less frequent migration of the metallic femoral component compared with the polyethylene acetabular component may be because the metal acts as a heat sink. Standard radiographs were inadequate for assessment of early mechanical loosening, whereas RSA could reveal migration within four months of the arthroplasty.

Output: Follow-Up Studies

Input: Consider Input: Abstract: The ability of extracranial-intracranial bypass surgery to alter favorably the natural history of ischemic cerebrovascular disease remains in question. A recently completed prospective randomized multicenter cooperative trial failed to confirm the hypothesis that the procedure prevents further cerebral ischemia in patients with atherosclerotic internal carotid artery or middle cerebral artery disease. We analyze findings of the study in detail, including possible effects on the natural history of the disease beyond the immediate perioperative period. Potential sources of bias that may have unpredictably affected the study are discussed. These include observational bias (patient and therapist not blinded), "randomization-to-treatment" bias (high morbidity after randomization but before operation), and "prerandomization" or allocation bias (patients in the study representing a selected sample of the population with cerebrovascular disease). The extensive analysis of secondary subgroups with small numbers of patients is discussed in light of the statistical methods used. Two particular classes of patients not addressed in the study who might benefit from the procedure are defined. They are patients failing the best available medical therapy and patients with clearly documented hemodynamic compromise. Possible indications for bypass surgery are suggested for the various lesions in light of the trial and of recent reports on the natural history and pathophysiology of ischemic cerebrovascular disease. Selected cases illustrating these indications are presented.

Output: Adult

Input: Consider Input: Abstract: In a cross-sectional survey of 652 workers in a western red-cedar sawmill, we obtained data on symptoms, pulmonary function, immediate skin reactivity to common allergens, nonspecific bronchial responsiveness, total IgE level, and sensitization to plicatic acid conjugated with human serum albumin as measured by RAST. Dust exposure was estimated by personal and area sampling for total dust during a work shift and cumulative exposure by duration of employment. Seven percent of the workers had an elevated RAST, and 20% had nonspecific bronchial hyperresponsiveness. Elevation in RAST was associated with bronchial hyperresponsiveness. Almost half (46%) of the workers with RAST elevation had bronchial hyperresponsiveness compared to 18% in workers with no RAST elevation. The association was unaffected by total IgE level or by limiting the analysis to workers without respiratory symptoms and was most apparent in younger workers. Bronchial hyperresponsiveness was associated with increased prevalence of respiratory symptoms as well as with lower levels of pulmonary function. The likelihood of bronchial hyperresponsiveness increased with increasing age but was unrelated to the dust-exposure concentration. RAST elevation was unrelated to employment duration or dust exposure and was not associated with an increased prevalence of symptoms or lower levels of pulmonary function independent of bronchial hyperresponsiveness. We conclude that plicatic acid-specific IgE and nonspecific bronchial hyperresponsiveness are associated in western red-cedar workers and that this association may reflect a causal connection.
Output: Adult