Anterior cruciate ligament reconstruction (ACLR) aims to restore knee stability. However, there is limited knowledge regarding the evolution of spatiotemporal gait variables in the first postoperative months, which is crucial for optimizing exercises protocols.

To identify spatiotemporal gait differences between the preoperative period and 15, 30, and 60 days after ACLR.

A longitudinal study was conducted with participants undergoing ACLR, followed by up to 60 days of physical therapy. Gait was assessed using GAITRite® in the preoperative period and at 15, 30, and 60 days postoperative (PO). Single support, double support, swing phase, and stance phase were analyzed using the generalized estimating equation model with specific syntax and the Bonferroni post hoc test in SPSS®, with a 5 % significance.

Sixteen participants were evaluated (13 men and 3 women), with a mean age of 26 year (SD = 7.57), weight of 82 kg (SD = 17), and height of 1.72 m (SD = 0.89). Comparison between the ACLR and control limbs revealed significant differences at PO15: single support (P < 0.005), swing phase (P < 0.009), and stance phase (P < 0.009). In the ACLR limb, differences were found in single support between preoperative and PO15 (P < 0.0001) and PO30 (P = 0.021), as well as between PO15 and PO30 (P = 0.001). For double support, significant differences were observed between preoperative and PO15 (P < 0.0001), PO30 (P < 0.0001), between PO15 and PO30 (P < 0.0001), PO15 and PO60 (P < 0.0001), and PO30 and PO60 (P < 0.0001). The swing phase showed differences between preoperative and PO30 (P = 0.010) and between PO30 and PO60 (P < 0.0001). In the stance phase, differences were observed between preoperative and PO30 (P = 0.012) and between PO30 and PO60 (P < 0.0001). In the uninjured limb, differences were found in single support between preoperative and PO30 (P = 0.007) and PO30 and PO60 (P < 0.0001). For double support, differences were observed between preoperative and PO15 (P < 0.0001), PO30 (P < 0.0001), between PO15 and PO30 (P < 0.0001), and PO15 and PO60 (P < 0.0001). PO30 was different from PO60 (P < 0.0001). The swing phase indicated differences between preoperative and PO15 (P = 0.001) and PO30 (P = 0.016). PO15 was different from PO30 (P = 0.003) and PO60 (P = 0.001), and PO30 was different from PO60 (P = 0.006). In the stance phase, significant differences were found between preoperative and PO15 (P = 0.001), PO30 (P = 0.015), between PO15 and PO30 (P = 0.003), PO15 and PO60 (P = 0.001), and between PO30 and PO60 (P = 0.008).

On PO15, the ACLR limb exhibited lower single support, a longer swing phase, and a shorter stance phase. Additionally, at PO15, single support was lower, and double support was greater. In the uninjured limb, at PO15, double support and stance phase were greater, while the swing phase was shorter. At PO30, the ACLR limb showed a decrease in single support.

There are significant differences in gait between the two lower limbs up to 60 days after ACLR, emphasizing the importance of targeting exercises strategies for each phase of the gait cycle and physical function.