Wiki 700 vs 800 icd9 codes

[desertsteph65]

I am studying for my COSC. This may be a stupid question but I thought 700 codes were diseases and 800 codes were injuries. On one of the questions in the workbook, it states patient injured shoulder while jet skiing. This was an old AC tear that he re-injured. The answer key picks all 700 codes and I had all 800 codes. What is the difference between the codes?
thanks

 

[mitchellde]

a re- injury, a chronic injury, a recurrent injury are all coded with the 7xx.xx codes. only the initial acute injury is coded with the 8xx.xx codes

 

[desertsteph65]

Thank You for clearing that up for me.