Femoral Tunnel Enlargements Following Arthroscopic ACL Reconstruction

Park, Seung Rim; Kim, Hyoung Soo; Kang, Joon Soon; Lee, Woo Hyoung; Lee, Seung Kyu; Chung, Hyun Kee

Abstract

Enlargement of bone tunnels has been noted on plain X-rays following arthroscopic ACL reconstruction. The cause of this widening is unclear, but it has been hypothesized that it may be due to either mechanical or biological cases. Ishibashi et al. reported anatomical proximal fixation resulted in the most stable reconstructed knee, with increasing instability as the level of fixation moved away from the tibial plateau. The purpose of this study is to determine if any difference exists in the amount of enlargement of the femoral tunnel following arhotoscopic ACL reconstruction with position of interference screw fixation and instability, and to know the factors which affected to the enlargement of the femoral tunnels. Total 39 patients were retrospectively reviewed for tunnel measurements radiologically at one year post-operation. (27 patients received bone-patellar tendon-bone autograft, 12 patients received bone-patellar tendon-bone autograft and Kennedy LAD-ligament augmentation device). The surgery was performed using an arthroscopic single and double incision technique. AP and lateral X-rays were obtained and the tunnels were measured by two independent observers using a digital caplper. The measurements were made at the widest part of the tunnel. Correction for magnification was performed by comparing the measured width of the interference screw used for fixation of the graft with its actual width. Statistical analysis was performed using a one-way analysis of variance(ANOVA) and t-test. 1. Radiographic tunnel enlargement of femoral side was average 2.42 mm (bone-patellar tendon-bone autograft : 2.36 mm, Kennedy-LAD and autograft : 2.56 mm)(p>0.05). 2. According to the position of the interference screw, the femoral tunnel enlargement were 2.25 mm in anatomical fixation, 2.40 mm in mid-tunnel fixation, 2.62 mm in mid-tunnel fixation, 2.62 mm in outer-tunnel fixation(p < 0.05). 3. The femoral enlargement according to the overall results(Clancy, 1982) were 2.39 mm in above good result group and 2.50 mm in below fair result group(p < 0.05). Tunnel enlargement group of femoral side was related to a distance between femoral articular surface and the position of interference screw. We conclude that femoral tunnel enlargement following arthoscopic bone tendon-bone ACL reconstruction is related to the mechanical effect rather than the properties of grafts and the clinical results.