Anterior cruciate ligament reconstruction after unicompartmental knee arthroplasty

Abstract 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.