Exam category: Procedures → Extremity (Other)
Why it matters: This module ties Procedures back to Image Production — pathology changes tissue density, and density changes the technique you need, so the "additive vs. destructive" distinction is really the exposure-factor logic from earlier paths applied to a clinical finding.
Three special studies here — bone age, skeletal survey, and hip-to-ankle long bone measurement — each answers a single question about the skeleton as a whole (how mature is it, is there disease or injury anywhere in it, or how do the two legs compare) rather than focusing on one joint. Then there's a general principle that applies everywhere: pathology either adds bone density or destroys it, and your technique has to follow.
A bone age study asks how mature a child's skeleton is. It's ordered for growth-potential assessment, for forensic purposes, and to identify pathologic growth delays — malnutrition, endocrine disorders, cystic fibrosis. What is imaged in nearly every case is a single PA of the left hand and wrist, because the hand and wrist ossify on a fairly consistent schedule with many centers to read at once.
Two methods turn that image into an age:
Memory cue — match the picture, add up the score: Greulich-Pyle matches a picture; Tanner-Whitehouse adds up a score.
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A pediatrician orders a bone age study. What is imaged in nearly every case?
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