Anterior cruciate ligament (ACL) rupture accounts for 50% of all knee ligament injuries and is related to sports practice in young and active patients. ACL reconstruction (ACLR) contributes to improving knee function, reducing joint instability, and assisting the patient in returning to their activities. However, even after reconstruction surgery and well-structured rehabilitation programs, residual rotational instability may remain in up to 30% of patients, which highlights the importance of assessing stability, balance, and postural control. However, although there are studies showing the impact on joint stability, there is still no knowledge about postural control in different periods of the postoperative period.

To establish the differences in bipedal and unipedal postural control before and after 15, 30, 60 and 120 days after ACL reconstruction surgery.

This is a pilot study evaluating 13 participants with ACL injury and surgical reconstruction who underwent analysis of bipedal and unipedal postural control before and after 15, 30, 60 and 120 days using a force platform. The variables analyzed were the center of pressure area (COP), anteroposterior amplitude (AAP), mediolateral amplitude (AML), anteroposterior velocity (VAP) and mediolateral velocity (VML). Three repetitions in bipedal support and three in unipedal support on the lower limb subjected to ACLR were evaluated. The mean of the attempts was considered as the result. The results were established by Repeated Measures Analysis of Variance. The assumptions were verified using Mauchly's sphericity test and when they were not assumed, an analysis was performed using the Greenhouse-Geisser correction. The F test, if a significant difference was identified, the Bonferroni multiple correction test was used. Significance was set at 5%. Analyses were performed using IBM-SPSS 29.

The participants were 10 men and 03 women, aged 25.09 (6.44) years, weighed 79.27 (16.67) kilos and measured 170.45 (8.64) centimeters in height. Postural control in the bipedal position showed no differences between the moments evaluated for COP (P = 0.107), AAP (P = 0.217), AML (P = 0.269), VAP (P = 0.432) and VML (P = 0.477). When the participants were in unipedal support, COP showed significant improvement (P = 0.025) with a difference between the preoperative moments (7.76 (2.17)) and after 120 days of surgery (5.93 (1.30)). The variables AAP (P = 0.085), AML (P = 0.089), VAP (P = 0.669) and VML (P = 0.248) did not show any changes.

ACLR improves postural control in single-leg stance by reducing the area of the center of pressure 120 days after surgery. These results establish the improvement in lower limb stability after ACLR.

Residual rotational instability may remain in up to 30% of patients. However, it is noted that ACLR has a beneficial impact on joint stability in different periods of the postoperative period, especially after 120 days of surgery.