## 4 Discussion
Less variability was seen when the QT autograft was chosen. Our measurements were performed 3 and 6 months post-surgery, but our results are similar to these previous ones (HT: 1.7 mm (SD 1.4) at 3 months and 1.5 mm (SD 1.4) at 6 months in our study vs. 3.1 mm (SD 1.3) in [PERSON] et al. ; QT: 0.9 mm (SD 0.7) at 3 months and 1.3 mm (SD 1.0) at 6 months for in study vs. 1.1 mm (SD 0.9) in [PERSON] et al.). We presented our results as a median (minimum-maximum; mean (SD)) because non-parametric tests were used, but in this case, for a better understanding, we showed the mean (SD). [PERSON] et al. [26], in their study where all patients were older than 18 years, measured the side-to-side knee stability with a Rolineter. After a little more than a year from surgery, no statistical difference was found between the QT and HT autografts. [PERSON] et al. [21] also studied the QT as a possible autograft. Although they compared it with the bone-patellar tendon-bone (BPTB) autograft, there were no statistical side-to-side differences between the grafts, using a KT-2000 (MEDmetric Corp, San Diego, CA, USA) arthrometer. They concluded that the QT graft has a comparable performance to that of the BPTB graft for ACL reconstruction, with less donor site morbidity. [PERSON] et al. [27] obtained the same results as [PERSON] et al. They made it clear that the QT is a viable option for ACL reconstruction. [PERSON] et al. [28] in their study obtained even more significant results. They concluded that, even though functional testing, knee laxity and re-rupture rates of the HT and QT grafts were similar, there was a tendency for a higher graft failure in highly active patients treated with the HT autograft. From reviewed studies and our results, we can clearly conclude that the QT is an excellent choice for ACL repair. It would be interesting to investigate the biological or mechanical properties that may influence the QT graft performance. It is known that tenocytes are the predominant cells in tendons and ligaments. They produce collagen and have an important role in donor site healing, regeneration after graft harvesting and ligamentization of the graft. It is assumed that they may promote a better knee functional outcome after QT harvesting due to the higher abundance of tenocytes and collagen in the QT than in other tendons. [29; 30]. Another reason may be hamstrings sparing. Hamstrings are important for knee stability. They are involved in the rotational, translational and varus/valgus stability of the knee. Their loss during HT harvesting before regeneration significantly alters the knee kinematics and stability [31]. The latest evidence of early rehabilitation after ACLR showed that there was no difference between the unsupervised and the supervised programs for laxity, subjective function, functional outcomes, strength and atrophy, as well as that the duration of the rehabilitation did not play a leading role in the laxity and subjective function [32]. However, the laxity measurement 3 months post-op with an acceptable side-to-side difference could allow the physiotherapist to adjust the home-based exercise program,putting more focus on limb strength symmetry and delaying the running-based exercises. The laxity measures 6 months after the ACLR with an acceptable laxity difference up to 1.5 mm could allow starting sports-based tasks and returning to sports activities. It has been reported that the outcomes after ACLR, in general, are not different according to sex [33]. Postoperative ligamentous laxity was reported to be similar in males and females after ACLR using the HT autograft [34; 35]. In our study, we found a statistically significant difference in knee laxity 3 months post ACLR with the HT autograft in favor of the female group. However, [PERSON] et al., in their systematic review and meta-analysis, stated that females had inferior outcomes in instrumented laxity [36]. We suggest that these results could help to understand and plan the rehabilitation process.