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Please explain to me how it is possible to have hip pain from pressure on a nerve in the low back. I had a nerve block at L5 and it completely took away my hip and lower leg pain.

Pain that begins in one body part or region but is felt somewhere else is called referred pain. There are some referred pain patterns that are well-known and physicians are aware of these. For example, pain from hip osteoarthritis can be felt in the front of the thig, the back of the thigh, and front of the knee, along the shin (lower leg), and even down into the calf. But other patterns of referred pain can be more difficult to understand and explain. Your nerve block at L5 in the lumbar spine is a good example. From animal studies we know that messages via the L4 to S1 level nerves do go to the posterior area of the hip capsule. In other words, it is possible that hip joint pain is transmitted along the L5 spinal nerve. This may be why the spinal nerve injection at L5 relieved the pain. But if the pain was really coming from the degenerated hip, then it makes sense that a lidocaine (numbing) injection into the hip joint would provide pain relief. But that hasn't been confirmed in human studies. Scientists suspect perhaps there are central mechanisms at play. Central mechanisms is a term used to describe pain messages that are transferred via the spinal cord to the brain. Once the pain message is sent along this pathway, the body doesn't seem to know how to turn the message off -- even when pressure is removed from the nerve. There is much we still do not understand about pain -- local pain, referred pain, radiating pain, central pain mechanisms. These are just a few examples of different types of pain patterns and pain mechanisms. Scientists continue to explore and study pain phenomenon in order to determine the origin and help patients find specific ways to alleviate their pain.

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