Description
【Objectives】
Positive pivot shift (PS) has been detected in 20-40% after anterior cruciate ligament (ACL) reconstruction. Residual grade 2- or 3-positive PS test in 0-20% of patients following the ACL reconstruction (ACLR). Positive PS test after the ACLR correlates with worsening functional outcomes. several surgical techniques have been developing to reduce the residual positive PS and restore the rotational instability.
The purpose of this study was to investigate the presence of the PS phenomenon in the non-injured side and the related factors in patients with ACL injuries.
【Methods】
139 patients (75 male and 64 female, 27years old) who underwent the primary ACLR and 50 patients who underwent the post screw removal surgery one year after the ACLR between July 2021 and June 2023 at our hospital were included in this study. Patients with a history of contralateral ACL injury were excluded.
The PS test was quantitatively measured using a three-dimensional electromagnetic sensor under general anesthesia just before the surgery.
The PS test was determined as a positive in case the tibial posterior translation was detected.
In the primary ACLR, patients were divided into two groups; the positive PS (PS+) group and the negative PS (PS-) group in the non-injured knee. Patients’ general background, the presence of knee hyperextension, and the tibial posterior acceleration during the PS test (m/s2) of both sides of the knee were investigated.
In patients with the removal surgery, the positive PS rate was investigated in both the injured and non-injured knee.
【Results】
The PS-positive were detected in 62 patients (44.6%) on the non-injured knee.
There were no significant differences in age and gender between the two groups, and the significant differences were found in the presence of the knee hyperextension (p < 0.05), and the tibial posterior acceleration in the affected side (5.81 ± 4.40 m/s2 in the PS+ group vs. 4.29 ± 2.27 m/s2 in the PS- group) (p < 0.01).
In cases of the removal surgery, the residual PS on the affected side was observed in 26 cases (60%). Among them, 13 cases (50%) were in PS+ group, and 13 cases (50%) were in PS- group.
The residual PS was found in 13/17 (76.5%) in the PS+ group and 13/33 (39.4%) in the PS- group (p < 0.05).
【Conclusions】
About half of the ACL-injured patients have provided the positive PS phenomenon on the non-injured side.
The tibial posterior acceleration of the injured knee was significantly bigger in the PS+ group than the PS- group.
In addition, 50% who had the residual positive PS one year after ACLR belonged to the PS+ group.
In cases who have the positive PS in the non-injured knee, it wound be the possibility that the residual PS was detected even after the ACLR.
