Anterior cruciate ligament reconstruction after unicompartmental knee arthroplasty.

PURPOSE

ACL deficiency may cause abnormal knee kinematics and is associated with a tenfold increase in surgical failures after unicompartmental knee arthroplasty, such as aseptic loosening of the tibial compartment and medial bearing instability. The current investigators hypothesized that in a knee with UKA, single-bundle ACL reconstruction would restore tibiofemoral translation to levels similar to those of the intact ACL.

METHODS

Two fresh frozen pelvis-to-toes specimens (four paired knees) were used. On each knee, medial unicompartmental knee arthroplasty was performed by a single surgeon. ACL reconstructions were performed by conventional single-bundle technique. Three trials of Lachman and pivot shift tests were performed and recorded for each knee with the ACL-intact, after sectioning the ACL and after single-bundle ACL reconstruction. A mechanized pivot shifter was used to perform the pivot shift maneuvers. A surgical navigation system (Praxim Grenoble, France) simultaneously tracked tibiofemoral kinematics.

RESULTS

There was a significant difference in lateral compartment translation during the Lachman and pivot shift tests between the ACL-intact/UKA knee and the ACL-deficient/UKA knee (P < 0.05). There was no significant difference in lateral compartment translation during the Lachman and pivot shift tests between the intact/UKA knee and the ACL-reconstructed/UKA knee (n.s.).

CONCLUSIONS

For both the Lachman test and the pivot shift test, single-bundle ACL reconstruction restored kinematics in the UKA knee to magnitudes similar to those in the ACL-intact knee.