Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

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: Mechanical loosening of total hip prostheses. A radiographic and roentgen stereophotogrammetric study.

Input: Consider Input: Abstract: To establish the prevalence of Mycoplasma hominis and Ureaplasma urealyticum in infants up to 3 months of age with suspected sepsis, blood, cerebrospinal fluid, and urine specimens from 203 patients with clinical signs and symptoms of sepsis were cultured for Mycoplasma in addition to routine bacterial cultures. Proved bacterial infections were identified in 24 patients, four of whom had bacteremia. M. hominis and U. urealyticum were not isolated from any of the 191 blood and 199 CSF specimens tested. Of 170 specimens of urine cultured for Mycoplasma, M. hominis was isolated in six patients, U. urealyticum in nine patients, and both organisms in one patient. Twelve of the positive cultures were voided urine specimens, and four were suprapubic bladder aspiration specimens. Genital mycoplasmas appear to be uncommon causes of sepsis or meningitis in young infants. Further studies are required to assess their role in abnormal conditions of the urinary tract in childhood.

Output: Role of genital mycoplasmas in young infants with suspected sepsis.

Input: Consider Input: Abstract: Mathematical models have been used since 1976 in an attempt to predict the progression of chronic renal failure. These models have used the serum creatinine level as either a reciprocal or logarithmic plot against time. The accuracy of such predictions are characterized by either a correlation coefficient (r value) or prediction error (time at which dialysis was predicted minus time at which dialysis actually occurred). Retrospectively, we analyzed 37 children who progressed to end-stage renal disease, grouped them by their respective primary diseases, and calculated both r values and prediction error for each individual and group. Although r values for each group (with the exception of patients less than 1 year of age) were comparable, prediction errors were widely disparate among the various groupings. Individuals within each of the groups had disparate values even though identical r values were present. These observations indicate that predictive models using serum creatinine levels are of limited clinical use and are least useful for patients younger than 1 year of age.
Output: Prediction of the progression of chronic renal failure in children: are current models accurate?