Tunnel enlargement after anterior cruciate ligament reconstruction in patients with post-operative septic arthritis.

Tunnel enlargement is a frequent issue after ACL reconstruction and the "synovial bathing effect" is thought to be among the biological factors contributing to this phenomenon. Since the amount and the pressure of the synovial fluid inside the knee joint are higher and the length of its presence is longer in patients with post-operative septic arthritis after ACL reconstruction, we reviewed the tunnel enlargement in these cases in order to better evaluate this phenomenon in such a hostile environment. The null hypothesis of this study was that the highly represented phenomenon of the "synovial bathing effect" that occurs in an infected ACL reconstruction would not affect the amount of post-operative tunnel widening. A case-control study was done. At a mean follow up of 10 months (range 9-11 months) eight patients with septic arthritis following ACL reconstruction (group A) were radiologically reviewed using a CT scan and the diameters of femoral and tibial tunnels were measured. The results were compared with a control group (B) of uncomplicated ACL reconstruction cases operated by the same surgeon using the same technique. Although patients of Group A experienced a bigger amount of tunnel enlargement than patients of group B both on femoral (9.53 +/- 1.07 vs. 9.35 +/- 1.52 mm) and tibial side (10.07 +/- 1.3 vs. 9.92 +/- 0.74 mm), no clinical or statistically significant differences were detected between the groups (P > 0.05). No significant tunnel enlargement could be detected in patients of group A when compared with patients of group B. This seems to minimize the role of biological factors contributing to tunnel widening.