Histopathologic assessment of healed osteochondral fractures

Purpose: To assess the histopathologic features of healed tissue to define its biological and biomechanical properties after internal fixation of oste ochondral fractures. Type of Study: Cohort study. Methods: The general prin ciple of management of detached acute ostcochondral fractures is reattachme nt of the fragment by internal fixation. but the opinions on the quality an d structure of the healed tissue that will be obtained after treatment is c ontroversial. This study included 13 patients with acute osteochondral frac tures who were treated arthroscopically and had surgical fixation providing joint-surface congruity. Patients with osteochondral fractures too small f or fixation or with the overlying cartilage frayed, and patients with assoc iated injuries were excluded from the study. The mean age of patients was 1 7 years (9 to 24 years). In 2 cases the fractures were localized at medial, in 7 at lateral femoral condyles, and in 4 at the patella. Internal fixati on materials were K-wires for I case, Herbert screws for 3, and mini cancel lous screws for 9 cases. The mean follow-up period was 6.3 years (3 to 13 y ears). On second-look arthroscopy, congruity of the joint surfaces and heal ed fractures was observed in all cases. Beside removal of the implant, punc h biopsies were performed extending to the osteochondral junction; biopsy s pecimens were taken front the junction of the articular margin of the fragm ent and the edge of the remainder of the articular surface. Results: On his tologic examination of the specimens, scarce mature chondrocytes among rege nerative stroma, which dyed more eosinophilic than the basophilic chondral stroma and which had a chondrocyte-like appearance, were seen. Maturation o f histologic architecture to hyaline or articular cartilage was not recorde d in any of these cases. Conclusions: The clinical results did not correlat e with the histologic findings. Despite the protected joint surface congrue nce, restoration of the hyaline cartilage at the chondral junctions could n ot be obtained.