## 4 Discussion  
The main finding of this study was that no differences were found between the proprioceptive versus the conservative postoperative rehabilitation, in the functional nor in the proprioception outcomes of the operated limbs. Although the rehabilitation program with the proprioceptive elements provided better knee stability, the difference was clinically meaningless. Therefore, the results of the current study suggest that there is no advantage to function in doing proprioceptive rehabilitation exercises following the ACL reconstruction, when compared with a traditional strengthening program. The results of the current study are similar to those of [PERSON] et al. (2013) and [PERSON] et al. (2014). [PERSON] et al. investigated patients after semitendinos' tendon ACL reconstruction. 10 participants were enrolled in a 12-week training program: five were assigned to the proprioceptive program and five to the isotonic one. [PERSON] et al. investigated 19 patients during 14 weeks: 14 were rehabilitated with the proprioception exercises and 15 with the strengthening exercises. We expanded the number of participants to 40: 20 rehabilitated with the proprioceptive elements and 20 with a conservative rehabilitation program, and prolonged the rehabilitation protocols to 6 months. Despite the increased number of participants and prolongation of the rehabilitation, the hypothesis that proprioceptive training would improve functional activity more than strengthening exercises was not supported. Recent studies by [PERSON] et al. on patients after the ACL reconstruction using tibialis anterior allografts, found that the proprioceptive training could significantly improve quadriceps and hamstring muscle strength after 6 months of training ([PERSON] et al., 2015). Additionally, [PERSON] et al., who studied patients after arthroscopic reconstruction of the ACL using an autogenous bone-patellar tendon-bone, found that the neuromuscular training resulted in improvement in the functional tests ([PERSON] et al., 2015). A specific neurocognitive and perceptive rehabilitation treatment was more efficient that the common physical therapy in the [PERSON] et al. study on patients after ACL reconstruction with patellar tendon ([PERSON] et al., 2015). These results are in clear contradiction to our conclusions. Moreover, all of these researchers found no statistically significant differences between studied groups in the subjective assessments. The strength of our study is that we have found a significant statistical relationship between the results of the subjective evaluation of the knee function and the values of the difference in the tibia shift in relation to the thigh, which confirms the important role of mechanical stabilization of the joint for its stability. This argues in favor of treating anterior instability with ACL reconstruction. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Subjective Test** & **Objective Test** & **r** & \(\boldsymbol{p}\) \\ \hline IKDC & Pk Trq/weight Ext & 0.615 & 0.004 \\ IKDC & Pk Trq—weight Ext & \(-\)0.614 & 0.004 \\ IKDC & VPC & \(-\)0.667 & 0.001 \\ Lachman & STRD\_EC & \(-\)0.645 & 0.002 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Subjective-objective tests correlation. r—Spearman Rho coefficient. \(p\) values are indicated. STRD_EC—deviations from the resultant of STR mean axes, eyes closed; VPC—Visual-proprioceptive control coefficient. In the presented work, only one patient received a score below good in the Lysholm scale, and eight subjects in IKDC scale. All of these patients with low self-esteem of the function of the operated limb were the subjects from the group rehabilitated without the elements of proprioceptive training. They also had lower values of strength and endurance parameters of the knee extensors. These results are similar to those presented in the literature on the assessment of proprioception and knee function [10].