Acetabular osteophytes highly correlated with symptomatic FAI pain

KEYSTONE, Colo. – Radiographic assessment of femoroacetabular impingement (FAI) uses a host of signs for diagnosis; however, researchers presenting a study here revealed that acetabular osteophytes and an anterior-posterior femoral offset may be the two most accurate.

Anil S. Ranawat, MD, and colleagues studied 60 consecutive patients (23 men and 37 women) with unilateral symptomatic hip pain, 54 of whom had positive signs for FAI. The investigators used the nonsymptomatic side as a matched cohort.

“We wanted to investigate the incidence of these radiographic findings and see if there are gender differences, and then compare these to pain scores to see if there is any correlation with the radiographic signs,” he said at the American Orthopaedic Society for Sports Medicine 2009 Annual Meeting.

All 60 patients had 2 X-rays -- AP pelvic and a cross-table lateral view -- and two fellowship-trained radiologists read the radiographs using computer software to assess 32 parameters.

They used WOMAC and Lysholm scores to correlate the X-ray findings and pain. Prediction of symptoms was carried out by logistic regression analysis using the backward stepwise method in the SPSS 16, Ranawat said.

Comparing the symptomatic to the asymptomatic hips, the researchers found that the symptomatic hips had higher pain scores, had more femoral head osteophytes and had less evidence of pincer disease, “which is kind of counterintuitive,” he said.

Comparing the genders, Ranawat and his colleagues found that women had more acetabular abnormalities, smaller head diameters, more circular femoral heads, more signs of coxa profunda, and had greater range of motion, he said.

In terms of the correlations, the researchers found that anterior-posterior femoral offset correlated to the worst pain scores.

“One of the most important findings was any degree of acetabular osteophytes increased the probability that this was a symptomatic hip,” Ranawat said.

“We know that there are a lot of abnormal radiographic findings in hip pathology. We don’t really understand the incidence, and we really don’t know what the relationship is to the presentation of FAI,” he said. “Hip studies have shown that the radiographic features of symptomatic hip pain are very much consistent with FAI: a decreased range of motion and signs of early arthritic changes. Our data collaborate a lot of this, and there are clear gender differences in these patients.”

Reference:
Ranawat AS, Dominique A, Rothenfluh MD, et al. Radiographic predictors of symptomatic femoroacetabular impingement. Presented at the American Orthopaedic Society for Sports Medicine 2009 Annual Meeting. July 9-12, 2009. Keystone, Colo.