What diagnosis codes would be assigned to a patient with prepatellar bursitis due to a prior crushing knee injury?

The correct choice assigns the diagnosis codes M70.42 and S87.02xS for a patient with prepatellar bursitis resulting from a prior crushing knee injury.

M70.42 specifically indicates "prepatellar bursitis," which is inflammation of the bursa located in front of the kneecap. This code is appropriate as it clearly specifies the condition being treated.

The second part of the code, S87.02xS, corresponds to sequela of a crushing injury of the knee. This implies that the patient has a history of a knee injury that continues to have effects, such as chronic bursitis in this case. The 'xS' at the end designates it as a sequela code, demonstrating that the bursitis is a consequence of the prior injury.

This choice effectively captures both the current condition and its causative event, providing a clear and accurate representation of the patient’s health status for billing and medical records. In contrast to other choices, which either misidentify the effects of the prior injury or incorrectly classify the bursitis, this selection represents a thorough understanding of how to utilize the coding structure to reflect a patient's history and their current diagnosis.