Hip Dysplasia Pain Discovery

Hip Dysplasia Pain Discovery

Increased amounts of pain chemicals found in adult hip dysplasia patients.


Some types of arthritis are caused by inflammation, or by internal chemical responses that eventually lead to deterioration of the joint surfaces and abnormal joint motion. However, hip dysplasia is thought to occur in the opposite sequence where the inadequate socket causes abnormal joint motion, damage to the joint surfaces and tears in the rim of the socket (torn labrum). There may be loose pieces of joint surface or worn out spots where bone rubs against bone. This is somewhat like having a rock in your shoe that will cause a blister or worse if it’s not removed as early as possible. This type of pain is considered mechanical pain because the painful sensation is from the damage itself and not from inflammation. However, that may not be the complete explanation.

Chinese researchers at Shanghai University School of Medicine have found that adults with painful hip dysplasia have an increased amount of a chemical in the blood and in the hip joint that increases the painful sensations and also causes inflammation.  That chemical is called Substance P and increases the sensitivity to pain. Perhaps that’s the body’s way of getting attention so the person seeks help quickly, but that’s not always possible, especially for people with advanced deterioration who are told to wait as long as possible because the only solution is a total hip replacement. Even younger people waiting for reconstructive surgery may have more pain as a result of this chemical and as a result of inflammation on top of the damaged joint or damaged supporting structures.

Doctors often prescribe ibuprofen and other medicines to settle down inflammation and that helps some people but not others. The purpose of these medicines is to get by until surgery can mend the problem, but surgery needs to be postponed as long as possible for hip replacements because the artificial parts start wearing out the moment they are put to use.

This research showing a specific protein that increases pain sensation may help develop medicines that can decrease pain better than non-specific pain medicines like NSAIDs, Tylenol and some of the nutritional supplements that are on the market today. It may turn out that there are some ways to specifically block Substance P and help decrease the pain until surgery can be performed.

Reference: Wang H, et al, “Increasing substance P levels in serum and synovial tissues from patients with developmental dysplasia of the hip (DDH).” BMC Musculoskelet Disord. 2014 Mar 19;15:92.