Here are a few tips for building an ICD-10-PCS code. Grab an ICD-10-PCS book, start in the index, and reference the root operation (a list of root operations with their definitions is found in Appendix A). Next, reference the body part, and any other specifications in the sub-terms of the index.
You will have a few characters provided by the index at this point. Find the corresponding table in the middle section of the ICD-10-PCS book correlating to your characters, for example we will be looking for 0MNP.
Staying in the row, next select the other characters from each column as appropriate. If the procedure is performed openly, 0 will be the fifth character (0MNP0..), if it is performed endoscopically, then 4 will be the fifth character(0MNP4..). The only options for character 6 and 7 are both ZZ. so put the code to sleep! 0MNPZZ is the code for an open release of a ligament in the left knee.
Of course, there is a lot much more detail to building an ICD-10-PCS code, this is just the beginning. Guidelines printed in the beginning of the code book provide essential information in building codes. Have fun!