An important finding of this study was that both techniques, large-size graft diameter and combination with extra-articular tenodesis, decreased the failure rate of ACL-R, rotatory laxity, and improvement of clinical outcome. However, the ACLR-LET combination group was superior to the large ACL-graft diameter group. The hypothesis was confirmed. This may be explained by the fact that, in the knee in the ACLR-LET combination group, there are two points of fixations, but in the ACL-R with large graft diameter group, there is only one point of fixation.
In regard to group A, with an 8.5–11 mm graft diameter, graft failure occurred in two (4.1%) of 48 cases. One case occurred without trauma at 6 weeks, which may be related to the faulty technique or failed graft healing. The second case occurred two years postoperatively, just before a follow-up examination with new significant trauma. Superior results were noted by Tang et al.  in their retrospective study on 394 patients. Graft failure was zero if the graft diameter was greater than 8 mm. The Swedish group  reported a decreased likelihood of graft failure after ACL-R in 560 cases with an increment in the hamstring autograft diameter between 7.0 and 10.0 mm. For every increment of 0.5 mm in the hamstring graft diameter, the likelihood of graft failure after primary ACL-R was 0.86 times lower. A biomechanical study  that tested 6 to 9 mm hamstring allograft diameters suggested that increasing tendon graft diameters by 1 to 2 mm will significantly lead to better graft strength.
In regard to group B with the ACL-LET combination, graft failure occurred in one (2.1%) of 47 cases. This is comparable to the multicentric study of Getgood . Graft-failure after the ACLR-LET combination was 4% out of 291 patients after 2 years. In a systematic study with an ACLR-LET combination, Grassi et al.  reported an ACL graft failure rate of 3.6% after different follow-up periods. After 20 years, in their long-term study with the ACLR-LET combination, Zaffagnini et al. found a failure rate of 2% of 52 patients
Rotatory instability markedly improved from preoperative to postoperatively, as identified by the pivot shift test (Fig. 5). In regard to group A, a positive pivot shift test was detected in 3 (6.5%) patients. This is comparable to Jurkonis et al., who found a positive pivot shift test in 8% of 88 patients, after 2 years with a graft diameter of 10 mm. To our knowledge, no other report in the literature, tested the role of graft diameter on rotatory laxity.
In regard to group B, a positive pivot shift test was detected in one (2.1%) patient. However, Guzzini et al. found in a group of female players after 4 years of combined reconstruction a positive pivot shift test grade I in 6.3% of their patients. Grassi et al.  found in their systemic review of 628 patients that 15% of patients with the ACLR-LET combination had a positive pivot shift test grade I, 1% had a grade II, and 1% had a grade III. These findings would actually support the conclusion of the review by Dodds et al., who stated that, the combined ACLR-LET reduces residual pivot shift test and improves the postoperative kinematics of the knee.
The combination of ACLR - LET (group B) decreases rotatory instability more than a triple graft ACL-R, with increased diameter (group A). The positive pivot shift test at follow-up (Fig. 5) was 2.1% versus 6.5%, respectively. However, the difference was statistically non-significant (P-value 0.32234). Biomechanical cadaver studies  support this conclusion; an ACL-R alone may be insufficient to restore internal tibial rotation to normal knee values, but a combined ACLR-LET can restore its rotational laxity. Zaffagnini et al. reported that, extraarticular augmentation reduces the stress on the intraarticular portion of the graft, allowing better integration and representing a restraint to peripheral rotations.
However, combined ACLR-LET can over-constrain internal rotation of the knee when the anterolateral capsule is intact . Hence, there is a concern that the addition of LET to the lateral side of the joint may increase the risk of post-traumatic OA . However, a recent systematic review found that, radiographic evidence of OA was not significantly increased in patients where ACL-R was augmented with LET compared to ACL-R alone .
In group A, the subjective IKDC score was 90.94% (Table 2). This agrees with Rhatomy et al., who found the IKDC score was 85.07 for the group with a large graft diameter of > 8 mm. Jurkonis et al. found the subjective IKDC score to be 89.24 after 2 years with a graft diameter of 10 mm. In group B, the subjective IKDC score was 91.9 points (Table 2). This is comparable to Zaffagnini et al. in their study, the IKDC score was 94.3 points for the ACL-LET combination. However, this score is better than Grassi et al. , who found in their systemic analysis to the combination of ACLR-LET, the IKDC score was 83.3 points. Getgood et al. found in their multicenteric study with a combination of ACLR- LET on 589 patients, the IKDC score was 87.3% after 2 years.
The subjective IKDC score is a predictive factor for the return to sports . Excellent IKDC scores (58 (63%) patients) were associated with a return to sport participation at a previous level in the current study (Table 6) than patients with lower scores. This agrees with Cheecharern et al. , who found high IKDC scores were associated with sports re-participation.
Objective IKDC scores were normal or nearly normal in group A in 43 (93.4%) patients (Table 2). Similar results were obtained by Jurkonis et al..The score was 94.3%, with a graft diameter of 10 mm.
Regarding group B, objective IKDC scores were normal or nearly normal in 44 (95.6%) patients (Table 2). Grassi et al. found the scores in a combined ACLR-LET to be normal or nearly normal in 86.2% of patients. Ferretti et al. found it normal or nearly normal in 100% of patients after 10 years.
In this study, the relationship between the clinical outcome and age, weight (BMI) and gender were examined. Concerning age correlation, age had a significant negative correlation to the subjective IKDC (in both groups A and B, p value < 0.00001) (Table 3). This result agrees with Magnitskaya et al. , who found patients below 30 years of age had higher IKDC score values within the first year of primary ACL-R. This means that being younger is associated with higher clinical performance.
BMI had a non-significant correlation with IKDC scores (p value was 0.257742 for group A and 0.495094 for group B) (Table 4). However, Kowalchuk et al., found higher BMI was correlated with lower IKDC scores. Gender had no correlation with IKDC scores (Table 5). This agrees with Tan et al., in a systemic review, who found IKDC scores were comparable between sexes.
The aim of ACL surgery is to improve knee stability, minimize the chance of failure, and optimize the return to pre-injury levels of sports. According to this study, this can be achieved by increasing the graft diameter or by combing it with extra-articular augmentation, or by both techniques in one patient.
As a conclusion, both large graft-diameter and combination with extra-articular tenodesis decrease ACL-graft failure rates, postoperative rotatory instability and improve clinical outcome. However, the combination of anterior cruciate ligament reconstruction with extra-articular tenodesis was more effective than large-sized graft cruciate ligament reconstruction.
The limitations of the study include that, most patients were not sports players and were not involved in contact pivoting sports as a risk factor for return to sports. Along with this, a short follow-up period of 2 years. However, despite our appreciation of the limitations of our investigation, we believe that the results of this study could be useful in the future development of prospective comparative studies.