Periprosthetic Mass after Total Hip Replacement / 대한고관절학회지

PURPOSE: To analyze the characteristics and causes of periprosthetic huge mass which occur after treatment by total hip arthroplasty. MATERIALS AND METHODS: Of the patients who had undergone total hip arthroplasty from January 2000 to October 2007, we retrospectively evaluated the 10 patients who suffered huge soft tissue mass. Five of these patients had received metal-on-metal bearing (group 1) prostheses, and the other 5 had received metal-on-polyethylene bearings (group 2). We evaluated the size and location of the mass, the extent of osteolysis, and the hematologic and pathologic examination results. RESULTS: Roentgenographically, the location of the masses varied from the acetabular area to the distal femoral stem. The mean mass diameter of all 10 patients was 14.6 cm(7-21 cm)x6.2 cm(3-9 cm)x7.2 cm(4-12 cm). Osteolytic lesions were found in 3 group 1 patients and 3 patients in group 2. High counts of lymphocytes and eosinophils were present in group 1. High counts of macrophages were present in group 2. CONCLUSION: The occurrence of osteolysis and huge soft mass after total hip arthroplasty is thought to be related to foreign body reaction by polyethylene wear particles and metal hypersensitivity. Outside-in patterned cortical thinning was considered to be indicative of a long standing periprosthetic soft tissue mass effect.

Paralabral Cysts and Their Correlation with Acetabular Disorder / 대한고관절학회지

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 25.1x12.5x13.8 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.