Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest were acquired . The lungs are clear . The heart size is normal . The mediastinal contours are normal . There are no pleural effusions . No pneumothorax is seen . Discontinuity of the cortex along the posterior aspect of the left seventh rib is consistent with a minimally displaced fracture . Subtle irregularity of the posterior 8th rib may represent a non-displaced fracture .
    OUTPUT:
    
1 . Minimally displaced fracture involving the posterior arch of the left seventh rib , and possibly also the left posterior 8th rib . 2 . No pneumothorax .