Evaluation of the Bone Bridge Between the Bone Tunnels After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction

Abstract

Background: Double-bundle anterior cruciate ligament (ACL) reconstruction is a technically demanding procedure; it requires drilling 2 tibial and 2 femoral tunnels. Tunnel communication, whether intraoperative or postoperative, is a serious complication: It jeopardizes knee stability and graft function. Hypothesis: During double-bundle ACL reconstruction, special aimers would be helpful to avoid intraoperative bone bridge fracture. The bone bridge between the bone tunnels would maintain its structural integrity, and no tunnel communication would be observed postoperatively because of tunnel widening. Study design: Case series; Level of evidence, 4. Methods: This prospective study included 32 patients undergoing double-bundle ACL reconstruction. A multidetector computed tomography study was performed at a mean of 17 months postoperatively. The thickness of the bone bridge between the bone tunnels was measured in the femoral and tibial sides on an axial and sagittal plane, respectively, at 3 locations: the level of the joint line, the midportion of the bone bridge, and the base of the bone bridge. The bone density of the bone bridge was measured in Hounsfield units in the same locations. Bone density of the anterior tibial cortex and lateral femoral condyle was measured for comparisons. Results: Tunnel communication occurred intraoperatively in 1 patient on the tibial side at the level of the joint line. In the rest of the patients, a well-defined triangular bone bridge was present between the 2 tunnels in the femoral and tibial sides. The thickness at the apex of the bone bridge was 2.0 and 2.2 mm for the femur and tibia, respectively. In addition, the density of the bone bridge at its apex was similar to that of cortical bone. Conclusion: This study demonstrated that double-bundle ACL reconstruction, as used with anatomic aimers, produces a low rate of tunnel convergence. The bone bridge remains intact postoperatively, although it is thin at the level of the joint line.