Is Acetabulum Retroversion Caused by Pelvis Dysfunction?

1. More athletes are being diagnosed with hip impingement.
2. Hip impingement and osteoarthritis may be caused by a rotated pelvis, specifically acetabulum retroversion.

Hip impingement and hip osteoarthritis are becoming more prevalent diagnoses for hip pain. Unfortunately, the causes of these conditions are not well established. One possible theory for these conditions is the presence of acetabular retroversion.

The acetabulum is the concave surfaces in the pelvis where the femoral head lies. Acetabular retroversion occurs when the acetabulum faces in a more posterolateral orientation.

For impingement cases, acetabluar retroversion is thought to cause a pincer type impingement, where the femoral neck contact the anterior rim of the acetabulum during hip motion.

In hip osteoarthritis, acetabular retroversion can alter the resting position femoral head on the acetabluar theoretically impairing the congruence of the joint and increase joint stress.

Possible Cause of Acetabular Retroversion

Recent studies suggest changes in the pelvis position, specifically changes in anterior and posterior pelvic tilt and with pelvic rotation. Many used to believe alterations in hip rotation were from too much or too little growth, but they may in fact occur from an asymmetry in the pelvis. Shi (2013) found patients with sacroiliac joint disorders had a great mean difference in left to right iliac crest width, suggesting that the two innominate bones are rotated differently in patients with SIJD.

Classification of Acetabular Retroversion

The acetabular is typically oriented 15 – 20 degrees anterior from the horizontal plane, while less than 14 degrees is considered moderate retroversion and 10 degrees of less is severe retroversion.  

Sacroilial Joint Dysfunction

Determining if the SI joint can influence retroversion is still not well understood. However, if the the innominate is externally and posteriorly rotated, then acetabular retroversion would follow. Unfortunately, the tests for identifying SI joint dysfunction are unreliable (Potter 1985). Now, a combination of tests can improve thereliability, but not greatly (Laslett 1994). 

Now What?

Unfortunately, we do not know the true cause of acetabular retroversion until more research is done comparing SI joint dysfunction and radiographs. This research could hopefully correlate these two findings and provide some more evidence. Nonetheless, acetabular retroversion is being more evident from early adapters in youth sports, requiring more research. 

However, improving the SI joint is likely an area to assess and hopefully treat if someone is having hip impingement or osteoarthritis. This is possible through many techniques, most commonly soft tissue techniques.

References:

1. Cibulka MT. Sacroiliac joint dysfunction as a reason for the development of acetabular retroversion: a new theory. Physiother Theory Pract. 2013 Dec 18. [Epub ahead of print].
2. Shi NN, Shen GQ, He SY, Guo RB. [X-ray characteristics of sacroiliac joint disorders and its clinical significance]. Zhongguo Gu Shang. 2013 Feb;26(2):102-6. Chinese.
3. Laslett M, Aprill CN, McDonald B, Young SB.Diagnosis of sacroiliac joint pain: validity of individual provocation tests and composites oftests. Man Ther. 2005 Aug;10(3):207-18.
4. Potter NA, Rothstein JM. Intertester reliability for selected clinical tests of the sacroiliac joint. nPhys Ther. 1985 Nov;65(11):1671-5.