Prevalence of Radiographic Morphology of Anterior Inferior Iliac Spine in the Thai Population
Thienpratharn S, MD1,2, Punyawatthananukool A, MD3, Lektrakul N, MD3, Lertwanich P, MD1
Affiliation : 1 Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand 2 School of Orthopedics, Institute of Medicine, Suranaree University of Technology, Nakhon Ratchasima, Thailand 3 Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Background : Subspine impingement, one of the causes of hip pain, is related to an abnormal morphology of the anterior inferior
iliac spine (AIIS). AIIS morphology is evaluated using Hetsroni’s classification (types I to III).
Objective : The purpose of the present study was to determine the prevalence of AIIS morphology in the Thai population.
Materials and Methods: The pelvic three-dimensional computerized tomography (3D CT) reconstructions of patients were
evaluated retrospectively. The inclusion criterion was an age between 18 and 50 years. The exclusion criteria were hips with a joint-
space width less than 3.5 mm, hips with center-edge angles less than 20 degrees, patients with primary or secondary tumors around
the hips, and hips with acetabular fractures. A series of four, 3D CT images of each patient, comprising anteroposterior, 30-degree
oblique, 60-degree oblique, and lateral views, were independently reviewed by two physicians. Both raters repeated the evaluations
after a 2-week interval. The differences between the raters were resolved by consensus.
Results : The 3D CT reconstruction images of 112 hips of 75 patients with an average age of 38.8 years were evaluated. Forty-one
patients (55%) were male. The most common AIIS morphology was type II, which was found in 72 hips (64%), followed by type
I (40 hips, 36%). There were no hips with type III morphology in this series. There was also no significant difference in the AIIS
morphologies of the males and females.
Conclusion : The most common AIIS morphology in the Thai population is type II, followed by type I.
Keywords : Anterior inferior iliac spine, Subspine impingement, Hip impingement, Hip pain, Groin pain
