## 4 Discussion  
### Analysis of ACL Recovery  
The key finding of this study suggests that the use of a knee brace with resistance has a significant positive impact on rehabilitation after anterior cruciate ligament (ACL) reconstruction, particularly in terms of knee flexion range. Compared with the control group, the experimental group had a greater maximum joint range of motion during the knee support phase, especially during the longer postoperative recovery phase, suggesting that the knee brace with resistance was effective in promoting the recovery of knee range of motion. This improvement may be attributed to the controlled yet progressive resistance, which allows for graded rehabilitation intensity, thereby optimizing tissue adaptation without overloading healing structures--a critical factor in moderate to severe ACL injuries [20]. Compared with the results of previous studies, the present study provides more significant supporting evidence. It has been noted that although ordinary knee braces are helpful for recovery after ACL, their effect is more limited, especially in the longer-term recovery process, where they fail to significantly improve the joint range of motion [21]. This discrepancy may stem from differences in rehabilitation intensity, as traditional braces provide passive support rather than active resistance-based stimulation, which is particularly beneficial for patients with higher baseline impairment levels [22].  
Figure 7: Comparison of joint coordination between different groups at time point T3.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **EG** & **CG** & **t** & \(p\) & **ES** \\ \hline F\({}_{\text{ACL}}\) & 0.51 \(\pm\) 0.13 & 0.63 \(\pm\) 0.17 & \(-\)2.24 & 0.030 & 0.69 \\ \hline \hline \end{tabular} Note: The F\({}_{\text{ACL}}\) was standardized according to the body weight (BW) of the subjects.  
\end{table}
Table 5: Comparison of ACL forces between different groups.  
In this study, the knee brace with resistance showed significant advantages at the T2 and T3 moments, and especially at the T3 moment, the knee range of motion of the experimental group was significantly higher than that of the control group, which is consistent with the findings of previous studies. However, previous studies have usually failed to observe such a significant difference, especially at the time point after one month postoperatively [23]. One possible explanation is that earlier research often included heterogeneous patient populations with varying injury severity, whereas our study's protocol emphasized controlled resistance progression, which may have amplified functional gains in patients with more pronounced initial deficits. The results of the present study suggest that the band resistance knee brace was able to perform better one month postoperatively, contributing to accelerated recovery of joint function, especially in terms of the ability to flex the knee [24]. This improved effect may be related to the design principle of the resisted brace, which strengthens the muscles around the knee joint by providing moderate resistance, which in turn helps to restore joint stability and range of motion [25]. Notably, the resistance levels in our study were tailored to individual tolerance, ensuring that rehabilitation intensity aligned with tissue healing stages--an approach that may explain the superior outcomes compared to fixed-support bracing in prior work [26].