2-BUNDLE ACL RECONSTRUCTION IMPROVES CONTROL OF THE PIVOT SHIFT IN-VIVO

Background: Studies have shown that normal tibio-femoral rotational kinematics is not regained following single-bundle ACL reconstruction and that 14–30% of patients may have a residual “pivot glide”. It has been suggested that 2-bundle reconstruction could better control this laxity, but this not been demonstrated conclusively in-vivo . This study tested the hypothesis that 2-bundle ACL reconstruction improves the control of the Pivot Shift. Methods: We measured the mean maximum tibial translation and coupled rotation occurring during the pivot shift (using a previously validated surgical navigation based methodology) in 35 consecutive patients undergoing hamstrings ACL reconstruction. 17 patients had a standard single-bundle reconstruction and 18 patients a 4-tunnel, 2-bundle reconstruction. 10 pivot shift tests were performed pre- and post operatively by a single operator and the differences compared. Results: The two groups were equally age and sex matched. There was no difference in pre-operative pivot shift measurements. 2-bundle reconstruction decreased the tibial rotation occurring with the pivot shift test more than single-bundle reconstruction (Table 1). There was no detectable difference in the control of tibial translation. Conclusions: This study quantifies, in-vivo, the differences between single and 2-bundle ACL reconstruction in controlling pivot shift. It suggests that anatomic, 2-bundle ACL reconstructions could reduce pivot instability more effectively than a single-bundle. Whether the 10% additional control of the rotational component of the pivot improves functional stability or is necessary every patient and, in the longer term, limits the development of gonarthrosis secondary to abnormal motions, remains to be seen