Extension of lumbar spine infection into osteoarthritic hip through psoas abscess.

We present a case of pyogenic lumbar discitis and septic hip arthritis, accompanied by a psoas abscess and pyogenic iliopsoas bursitis, for which the correct diagnosis was delayed. The patho-mechanism was speculated to be initial hematogenous infection in the lumbar spine that spread along the psoas muscle as a psoas abscess and then extended into the hip joint via the iliopsoas bursa. For an early correct diagnosis, clinicians should be aware that the lumbar spine and hip joint regions communicate through the psoas muscle space and iliopsoas bursa, making it possible for infection to spread.