## 3 Discussion
Instead of supervising ROM and weight bearing directly, we designed contraindications for training in sports centers based on the patient's subjective feelings and/or symptoms while indirectly observing the patient in the sports center. In our case, the treatment was considered effective because the patient was willing to return. Thus, in clinical practice, it is necessary to selectively attempt home-based training while considering patient adherence. In Phase I, knee flexion AROM and PROM recovered significantly. In the conservative protocol, hamstring resistance exercises are restricted for the first six weeks [63]. However, after closed-kinetic chain training, squats, and various other exercises in the current case, both knee flexion AROM and PROM improved (Table 2). Furthermore, the thigh circumference of the affected side recovered, and muscle atrophy was resolved. After confirming that weight bearing was possible, the program proceeded to Phase II, and a water exercise was added to restore the balance and function of the injured leg. This broke the existing rules for the four recovery stages (1. recovery stage, 2. repair stage, 3. strength stage, and 4. functional stage), and the patient recovered quickly without any risk. The patient was transferred to full functional activity one month after rehabilitation. As shown in Table 2, AROM of the injured leg recovered to the same level as that of the uninjured leg, and the goal of ROM recovery to 125\({}^{\circ}\) within 3-6 weeks was achieved [23]. The criterion that the quadriceps index for recovery should be at least 75% higher than that of the unaffected side was also met [50], and a value > 90% was observed. In Phase III, the difficulty of the balance and proprioceptive exercises increased through star excursion and trampoline movements with added weight, and strength was improved by increasing the weight. Early return to sport after an injury is important for team performance, and studies examining the time from isolated meniscal tears to return to play are rare. Regardless of such rarity, meniscal repairs are often performed in young athletes. After surgery, it is generally recommended for the athlete to return to competitive sports involving frequent physical contact only after 4-6 months [27; 51; 52; 53; 54; 55]. However, in the current case, only 71 days were required to complete all rehabilitation phases. In another study, it was reported that it takes 5.6 months on average for the recovery of an isolated meniscal tear [17]. Therefore, it can be said that the effectiveness of the function-oriented, aggressive rehabilitation protocol used in this study was proven. The ultimate goal of recovery is to create a problem-free state 5-10 years after surgery [64]. However, because the failure rate of patients who undergo accelerated rehabilitation after meniscal repair is 10% after 3.5-20 months [40; 50], the recurrence of injuries needs to be considered. In this context, we measured subjective function, isokinetic strength, and performance at a 10-year follow-up. We observed that the isokinetic muscle strength of the affected side exceeded 90% of that of the unaffected side. The results of the performance and subjective function measurements also suggested that the effect of the injury as an active player was eliminated. In particular, as is evident from the evaluation of single-leg forward, lateral, and medial hops (Table 4), no asymmetry between the injured and non-injured legs was observed in functional movements. After the follow-up, we prioritized evaluating the functional fitness required in sports situations to confirm that there were no problems for the patient with performing athletic activities. Our study has certain limitations. First, although the player quickly returned to the game after the rehabilitation exercises, an assessment of fitness function was not conducted immediately after completion of the rehabilitation program.