Differences in Acetabular Rim Thickness in Patients with Unilateral Symptomatic Pincer-Type Femoroacetabular Impingement. Issue 7 (18th July 2016)

• Record Type: Journal Article
• Authors: Weber, Alexander E.; Kuhns, Benjamin; Cvetanovich, Gregory; Inoue, Nozomu; Nho, Shane Jay
• Is Part Of: Orthopaedic journal of sports medicine. Volume 4:Issue 7(2016.)Supplement 4
• Publication Date: 2016-07-18
• Subjects: Sports medicine -- Periodicals; Orthopedics -- Periodicals; Arthroscopy -- Periodicals; Arthroplasty -- Periodicals; Knee -- Surgery -- Periodicals; 616.7
• DOI: 10.1177/2325967116S00146
• Languages: English
• ISSNs: 2325-9671

Abstract

Objectives: The objective of this study was to identify the location and magnitude of difference in acetabular rim morphology between the symptomatic and asymptomatic acetabula in a cohort of patients with symptomatic unilateral pincer-type FAI. Methods: After IRB approval, computed tomography (CT) scans of 43 patients (22 males, 21 females) diagnosed with unilateral pincer-type FAI were obtained. CT images of both hips were imported in DICOM format and segmented into 3-dimensional (3D) hemi-pelvises using 3D reconstruction software (Mimics, Materialise, Leuven, Belgium). The point-cloud data of the asymptomatic hemi-pelvis was mirrored onto the symptomatic side. Protrusion of the symptomatic side was recorded as a positive value and appeared as red on the color map (Figure 1). Data was collected in 3° intervals and analyzed by quadrant using the clock face method; reflecting the 12-3, 3-6, 6-9, and 9-12 o'clock positions. Results: The symptomatic acetabular rim was on average 0.39 ± 0.36 mm thicker than the corresponding location on the asymptomatic rim. When the acetabular clock face was broken up into quadrants, reflecting the 12-3, 3-6, 6-9, and 9-12 o'clock positions, the 12-3 o'clock position demonstrated the greatest difference between symptomatic and asymptomatic sides (Table 1). The 12-3 o'clock quadrant demonstrated significantly greater difference between symptomatic and asymptomatic sides (0.53±0.22 mm) as compared to the 3-6 o'clock position (0.39±0.27 mm; p=0.006), the 6-9 o'clock position (0.34±0.05 mm; p<0.001), and the 9-12 o'clock position (0.33±0.03; p<0.001). There was no correlation between gender and magnitude of difference at any location. Conclusion: Small changes in acetabular rim morphology, on the order of 0.5 mm or less can be the difference between symptomatic pincer-type FAI and the asymptomatic state. Knowledge of the healthy, unaffected side in unilateral FAI may provide a better template for rim recession rather than broadly applying previously described anterior or lateral center-edge angle parameters.