ePoster #811 - ISHA Annual Scientific Meeting 2016

The Accuracy of X-Ray Based Radiographic Parameters of Pincer Type Deformity and the Prevalence in General Korean Population

Sung Hoon Yang, MD, Gwangju KOREA, REPUBLIC OF
Dong Hwi Kim, MD, Gwangju SOUTH KOREA
Yong Chul Jeon, MD, Gwangju KOREA, REPUBLIC OF
Sang Hong Lee, MD, PhD, Gwangju KOREA, REPUBLIC OF
Suenghwan Jo, MD, PhD, Gwangju SOUTH KOREA

Chosun University Hospital, Gwangju, KOREA, REPUBLIC OF

FDA Status Not Applicable

Summary: The study indicated nearly 20% of Korean population has pincer type morphology and checking the prominent ischial spine sign can provide highest accuracy for detecting retroversion of the acetabulum.

Introduction : The prevalence and diagnostic criteria for cam type impingement has been well described but there is limited study on pincer type impingement. This study aims to investigate the 1) accuracy of x-ray based radiologic signs of Pincer criteria and 2) to report the prevalence of radiologic signs of pincer morphology in general Korean Population. Materials and methods : The study comprises of 504 patients between age 18 and 60 years who had taken pelvic computed tomography (CT) scan between January 2011 and December 2015 due to a traumatic event. Exclusion criteriaes were the patients who did not have accurate pelvis anteroposterior radiography, diagnosed with pelvic or acetabular fracture and presence of protrusion acetabula (deep acetabular socket). The x-ray based radiographic signs including cross over sign, posterior wall sign and prominent ischial tuberosity sign were checked by two evaluators. To evaluate whether the x-ray based parameters accurately reflects the retroversion of the acetabulum, the axial CT scan was utilized to measure the cranial version of the acetabulum. Each x-ray based radiographic parameters were compared with the CT based version measurements to evaluated whether they accurately reflects the retroversion of the pelvis. Also, the prevalence of overall radiographic pincer deformity were calculated. Results : The cross over sign was positive in 18.4%, posterior wall sign in 17.9% and ischial tuberosity sign in 16.3%. The cranial version of the acetabulum as measured by CT axial view, showed retroversion in 7.9% of the subjects while the prevalence was 13.6% for the central retroversion. Among the x-ray based parameters for detecting retroversion of the acetabulum, ischial tuberosity sign showed the highest sensitivity (83.3%) while all three parameters had high specificity (76%). For detecting central retroversion, sensitivity was low for all three parameters while sensitivity was uniformly high. With the parameters used, the radiologic pincer morphology was observed in 16 to 18% of the subjects. Conclusions : The current study indicates that for the radiologic diagnosis of the pincer type deformity, checking the prominent ischial spine sign will provide highest accuracy to detect the retroversion of the acetabulum. Also, the study suggests overall prevalence of pincer type morphology was observed in approximately 16-18% of the general Korean population.