QUANTITATIVE-ANALYSIS OF SYNOVIAL FIBROSIS IN THE INFRAPATELLAR FAT PAD BEFORE AND AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

We performed quantitative analysis of synovial fibrosis in the infrapa tellar fat pad in 26 patients who underwent arthroscopically assisted anterior cruciate ligament reconstructions. Twelve patients underwent reconstruction with patellar tendon autografts, and 14 had reconstruct ions with semitendinosus and gracilis tendon autografts. Synovial samp les were obtained at the time of reconstruction from 10 patients and a t second-look arthroscopy from all 26 patients. Sections from quick-fr ozen samples were stained with either hematoxylin and eosin or Fast gr een and Sirius red. We used sodium hydroxide in absolute methanol to e lute the Fast green and Sirius red stains, and the total collagen cont ent of each section was estimated by measuring the optical density of the eluted solution. The volume of each section was determined on a co mputer using an imaging program, and collagen content per unit of tiss ue was calculated. Median collagen content was 15.3 mu g/mm(3) for the preoperative samples, 25.1 mu g/mm(3) for the group with patellar ten don autografts, and 27.1 mu g/mm(3) for the group with hamstring tendo ns autografts. Analysis of preoperative and postoperative paired sampl es revealed a significant increase in synovial collagen after anterior cruciate ligament reconstruction. We observed increased fibrosis in p atients who had pain on exertion or stiffness in squatting after the r econstructive surgery.