Acetabular Retroversion Possible Cause of Pain Later in Life Among Those with Developmental Dysplasia of the Hip
Developmental dysplasia of the hip is a dislocation of the hip that affects one or both hips from birth. It can range from mild and not noticeable until the child walks to severe and immediately identified. While in most cases the condition can be treated successfully, it has been found that later on in life, patients are prone to hip problems that can be related back to the dysplasia. Although doctors don't know exactly why there could be later life problems with the hip, such as osteoarthritis, one theory is that the pressing of part of the femur (thigh bone) against the pelvic wall could result in tissue damage over the years.
The authors of this article examined how often there was this type of pressure caused by acetabular retroversion (part of the femur tilting back or turning onto the pelvic bone) and how it could relate to patients with developmental dysplasia of the hip. To do this, researchers recruited 59 patients (52 females) who had been diagnosed with developmental dysplasia of the hip as a child. Combined, they had a total of 96 hips with developmental dysplasia. Their age at the time of the study was an average of 40.1 years, ranging from 15 to 60 years. Eleven patients had received treatment for congenital dislocation of the hip. Of 48 patients, 69 hips were symptomatic, which means they were causing pain and discomfort. The hip dysplasia group was compared with a control group of 44 subjects (40 females), who ranged in age from 52 to 83 years, with an average of 75.1 years. No-one in the control group had any hip abnormalities or degeneration.
The researchers took x-rays of all subjects, looking at the joint and at movement, measuring angles that the hips could bend comfortably. Computed tomography scans (CT scans) were also performed on the patients with developmental dysplasia. Upon examination for the study, 69 hips were reported as painful in the study group.
The results showed that 18 percent, or 17 of the 96 hips, in the study group had developed acetabular retroversion and the angle at which they could bend was smaller than those who did not have the problem. In the control group, who did not have hip problems, there this affected only 4 percent, or two of 50 hips. There were also signs of acetabular anteversion, where the top of the bone tilted forward, but this occurred in far fewer hips and at smaller angles.
The onset of pain in adulthood began, on average at 27.9 years of age in those patients with the positive acetabular retroversion because of damage within the joint. Among the hips without this, the average age of pain onset was 40.5 years. Patients with acetabular retroversion had almost a four times higher risk of pain onset than those with acetabular anteversion. And, body mass index also played a role in the onset of hip pain.
The authors concluded that there was a connection between earlier developmental dysplasia of the hip and later onset of hip pain, caused by acetabular retroversion.
Masanori Fujii, MD, et al. Acetabular Retroversion in Developmental Dysplasia of the Hip. In The Journal of Bone & Joint Surgery. February 2010. Vol. 92. No. 4. Pp. 895-903.