Purpose: To evaluate the correlation between MRI findings and hip joint lesions evaluated by arthroscopy in patients affected by paralabral cyst.
Materials and Methods: Of patients treated by hip arthroscopy from Jan 1996 to Mar 2010, 17 cases symptomatic of paralabral cyst as observed by preoperative MRI were analyzed. The presence of an acetabular labrum tear, and the location and size of the cyst were evaluated using both preoperative MRI and intraoperative arthroscopy. Visual analogue scale (VAS), modified Harris hip scale, and Hip outcome score results were compared as determined by the two assessment methods.
Results: According to the MRI findings, the locations of the cysts included 5 cases in the anterosuperior, 2 anterior, 4 anteroinferior, 2 posterosuperior and 4 posteroinferior. The mean size of all cysts was 25.1×12.5×13.8 mm³. Postoperatively, the mean VAS score for all patients improved from 7.7 to 1.5, their modified Harris hip score improved from 58.8 to 90.7, and their Hip outcome score improved from 54 to 93.5.
Conclusion: Painful paralabral cyst was mainly associated with an acetabular labral tear and we concluded that observation of paralabral cyst upon preoperative MRI provided indirect evidence of proximal acetabular labral pathology.

Keywords: Hip, Paralabral cyst, Acetabular labral tear