AAOS Now tests your knowledge of orthopaedic trivia. Take a minute and see how well you know your orthopaedic trivia—but don’t peek at the answers! An expanded explanation of the correct answers can be found in the online version, available at www.aaosnow.org

1. What is the correct term for the bone whose name means “little key”?
1. Sternum
2. Scapula
3. Clavicle
4. Xiphoid
2. For how many people was Sinding-Larsen-Johansson syndrome named?
1. One
2. Two
3. Three
4. Four
3. How many vertebra most commonly make up the coccyx?
1. Two
2. Three
3. Four
4. Five
4. Dupuytren contracture is most common in people of what ancestry?
1. Native American
2. Spanish
3. Viking
4. Japanese
5. Orthopaedists love their acronyms! How many of the following can you define?
1. PASTA
2. PLIF
3. DISI
4. SLAP
5. STIR sequence

If you have orthopaedic trivia you think would be of interest to AAOS Now readers, email it to aaoscomm@aaos.org;;

Answers
1-C. Clavicle is Latin for “little key.” Although most say the name reflects the shape of the bone, some suggest that it was so named because it appears to “close and lock” the bones of the chest

2-B. Two: Christian Magnus Flasen Sinding Larsen (Norwegian) and Sven Johannson (Swedish)

3-C. The coccyx usually is formed of four rudimentary vertebrae.

4-C. Although the cause of Dupuytren contracture is not well defined, it is known to run in families: 60% to 70% of individuals with Dupuytren contracture have a family history of the condition. It is most common in older (> 40 years) men (approximately 10:1 male:female) with Northern European ancestry (e.g., those with a Viking ancestry).

5-A. Partial articular supraspinatus tendon avulsion; B. Posterior lumbar interbody fusion; C. Dorsal intercalated segment instability; D. Superior labral tear from anterior to posterior; E. Short-tau inversion recovery