***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The aim of this study was to evaluate whether  anterior cruciate ligament ( ACL ) reconstruction using the double bundle technique ( DB ) improves stability in the knee compared with the single bundle technique ( SB ) with the femoral tunnel in a more horizontal position ( 2 or 10 o’clock ) . We conducted a r and omized , prospect i ve study . Forty patients were r and omized to the DB group ( 20 patients ) and the SB group ( 20 patients ) .  Four-str and ed semitendinosus and gracilis autologous grafts were used in the SB group and in the DB group the conventional four tunnel technique was carried out using the same tendons . The IKDC complete form was used for the preoperative evaluation , and in the follow-up the IKDC subjective knee evaluation form , IKDC current health assessment form and IKDC knee examination form were used . Anteroposterior ( AP ) laxity was evaluated by st and ardised and forced radiology in all patients . No significant preoperative between-group differences were found . During the follow-up , no differences were found between groups , except for significant between-group differences ( P < 0.05 ) between the preoperative and postoperative evaluations . The IKDC index also showed significant differences in the 2-year follow-up . Median scores increased from 48 ( range 41–54 ) to 81 ( range 75–87 ) ( P = 0.01 ) in the SB group and from 52 ( range 46–58 ) to 80 ( range 72–88 ) ( P = 0.02 ) in the DB group . There were no significant differences between the groups in terms of functional scores . In conclusion , the 2 and 10 o’clock placements showed no significant differences between SB and DB techniques in the pivot-shift test , manual and radiological anterior posterior laxity and IKDC scores . However , significant between-group differences were found between the preoperative and postoperative evaluations Twenty-six patients with anteroposterior ( AP ) laxity of the knee , associated with torn anterior cruciate ligament ( ACL ) , were prospect ively r and omized for arthroscopic lower femoral tunnel placed single- or double-bundle reconstruction using hamstring tendons . We evaluated AP and rotational stabilities under regular loads ( a 100-N anterior load and a 1.5-N m external – internal load ) before and after ACL reconstruction , comparing single- and double-bundle reconstruction with our original device for applying quantitative tibial rotation and the navigation system intraoperatively . No significant differences were found between the two groups in AP displacement and total range of tibial rotation at 30 ° and 60 ° of knee flexion . We found that a lower femoral tunnel placed single-bundle reconstruction  reproduced AP and rotational stability as well as double-bundle reconstruction after reconstruction intraoperatively Purpose To prospect ively assess the anterior tibial translation and rotational kinematics of the knee joint as well as the clinical outcome after  single-bundle ( SB ) and double-bundle ( DB ) anterior cruciate ligament ( ACL ) reconstruction .  Methods Forty-two patients r and omly underwent single-bundle ( Group SB , n = 21 ) or double-bundle ( Group DB , n = 21 ) ACL reconstruction using hamstring tendon autografts .  Anterior tibial translation and rotatory laxity were measured prior to and after fixation of the graft during reconstruction under the guidance of a navigation system . Clinical outcome measurements included the evaluation of the joint stability and functional status . Results Anterior tibial translation and rotatory laxity were improved significantly at all degrees of knee flexion in both groups . The postoperative total rotation ( sum of internal and external rotation ) at 30 ° and 60 ° ( 26.6 ° vs. 24.0 ° ; 28.7 ° vs. 25.1 ° ) as well as postoperative change in external rotation at 60 ° ( −1.4 ° vs. −4.6 ° ) , and a change in total rotation at 30 ° and 60 ° ( −7.0 ° vs. −11.5 ° ; −6.1 ° vs. −8.9 ° ) differed between the two groups , with better stability in the DB group . At 2 years follow-up , IKDC subjective satisfaction score was significantly different between two groups ( 70.9 vs. 79.6 ) , while manual and instrumented laxity , pivot shift tests , modified Lysholm score , Tegner activity score , thigh muscle strengths were not different . Correlation analysis showed little correlations between anterior laxity tests at follow-up , and the kinematic variables measured by navigation during surgery while pivot shift test , IKDC subjective satisfaction score , modified Lysholm score , and Tegner activity score were mainly correlated with navigation-measured rotations in both groups . Conclusions The kinematic tests in this study found evidence suggesting that the DB ACL reconstruction  improved rotatory laxity better than the SB ACL reconstruction at 30 ° and 60 ° of flexion , but there was no difference in functional outcome at 2 years follow-up between SB and DB groups . Level of evidence Prospect i ve comparative study , Level II We conducted a prospect i ve r and omised study of anatomical single-bundle ( A-SB group ) versus double-bundle ( A-DB group ) anterior cruciate ligament ( ACL ) reconstruction using the hamstrings tendons . Twenty patients with unilateral ACL deficiency were r and omised into two groups . We created the bone tunnels at the position of the original insertion of the anteromedial bundle footprint and posterolateral bundle footprint in the A-DB group and at the central position between these two bundles in the A-SB group . All of the patients were tested before ACL reconstruction and one year after surgery . The KT-1000 measurements , isokinetic muscle peak torque and heel-height difference were evaluated and the general knee condition was assessed by Lysholm score . For pre- and postoperative stability assessment , we used the six-degrees-of-freedom of knee kinematic measurement system using an electromagnetic device ( the EMS ) for quantitative assessment during the Lachman test and the pivot shift test . There were no significant differences in the KT-1000 measurements , isokinetic muscle peak torque , heel-height difference , and Lysholm score at one-year follow-up between these two groups . The EMS data showed there were significant differences in the acceleration of the pivot shift test between the operated knee and the contralateral normal knees in the A-SB group . In conclusion , clinical outcomes were equally good in both groups . However , the EMS data showed the anatomical double-bundle ACL reconstruction tended to be biomechanically superior to the single-bundle reconstruction Purpose The purpose of this study was to compare subjective , objective and radiographic outcome of the lateralized single-bundle bone-patellar tendon-bone autograft with a non-anatomical double-bundle hamstring tendons autograft anterior cruciate ligament ( ACL ) reconstruction technique at long-term follow-up . Methods Seventy-nine non-consecutive r and omized patients ( 42 men ; 37 women ) with unilateral ACL insufficiency were prospect ively evaluated , before and after ACL reconstruction by means of the above-mentioned techniques , with a minimum follow-up of 8 years ( range 8–10 years ; mean 8.6 years ) . In the double-bundle hamstrings technique , we used one tibial and one femoral tunnel combined with one “ over-the-top ” passage , cortical staple ’s fixation and we left intact hamstrings ’ tibial insertion . Patients were evaluated subjectively and objective ly , using IKDC score , Tegner level , manual maximum displacement test with KT-2000 ™ arthrometer . Radiographic evaluation was performed according to IKDC grading system , and re-intervention rate for meniscal lesions was also recorded . Results The subjective and objective IKDC were similar in both groups while double-bundle hamstrings group showed significantly higher Tegner level ( P = 0.0007 ) , higher passive range of motion recovery ( P = 0.0014 ) , faster sport resumption ( P = 0.0052 ) , lower glide pivot-shift phenomenon ( P = 0.0302 ) and lower re-intervention rate ( P = 0.0116 ) compared with patellar tendon group . Radiographic evaluation showed significant lower objective degenerative changes in double-bundle hamstrings group at final follow-up ( P = 0.0056 ) . Conclusion Although both techniques provide satisfactory results , double-bundle ACL reconstruction shows better functional results , with a faster return to sport activity , a lower re-operation rate and lower degenerative knee changes Purpose The effect of double-bundle ACL reconstruction on knee kinematics has recently been studied by several authors under controlled laboratory conditions however little evidence has been derived from dynamic in vivo evaluations . This study hypothesized that tibial rotation during pivoting motor tasks would be better restored after double-bundle ACL reconstructions when compared with single-bundle procedures . Methods Twenty patients with a chronic ACL rupture were r and omly assigned to receive a single- or double-bundle ACL reconstruction . Both knees were evaluated pre-operatively by kinematic 3-D gait analysis while performing low- and high-dem and motor tasks , including pivoting . At 6 months post-operatively , measurements were repeated in 16 patients . Ten healthy , sex- and age-matched subjects with no history of lower limb pathology formed the control group . The tibial rotational excursion was set as the dependent variable . Results The results indicate that at 6 months after surgery both “ anatomic ” single- and double-bundle ACL reconstruction are able to restore tibial rotational excursion when compared with the contralateral knees and with control knees from uninjured subjects . Chronic ACL-deficient patients show an increase in tibial rotation in both knees during high-dem and pivoting tasks . Conclusions Both “ anatomic ” single- and double-bundle ACL reconstruction adequately restore tibial rotational excursion in a human , “ in vivo ” kinematic model . As knee stability measurements by in vivo kinematic 3-D analysis more accurately represent actual knee loading during activities , the results of this study might better correlate with functional outcome after ACL reconstructions compared with static knee stability tests or ex vivo laboratory experiments . In such , the results of this dynamic study do not support the theoretical advantage of a double-bundle ACL reconstruction over an “ anatomic ” single-bundle ACL reconstruction . Level of evidence II Purpose Combinations of intra- and extra-articular procedures have been proposed for  anterior cruciate ligament reconstruction  with the aim of achieving an optimal control of translational and rotational knee laxities . Recently , the need for better reproducing the structural and functional behavior of the native anterior cruciate ligament led to the definition of anatomic double-bundle surgical approach . This study aim ed to quantitatively verify whether the in vivo static and dynamic behavior obtained using over-the-top single-bundle with extra-articular tenodesis reconstruction was comparable to the results achieved by anatomic double-bundle approach . Methods Thirty-five consecutive patients , with an isolated anterior cruciate ligament injury , were included in the study .  St and ard clinical laxities and pivot-shift test were quantified before and after anterior cruciate ligament reconstruction by means of a surgical navigation system dedicated to kinematic assessment ; displacements of medial and lateral compartment during stress tests were also analyzed . Results Single-bundle with extra-articular tenodesis approach presented statistically better laxity reduction in varus/valgus stress test at full extension and in internal/external rotation at 90 ° of flexion ; lateral plasty controlled better the lateral compartment during drawer test and varus/valgus stress test both at 0 ° and 30 ° of flexion and both the compartments during internal/external rotation at 90 ° of flexion . On the other h and , pivot-shift phenomenon was better controlled by anatomic double-bundle reconstruction . Conclusions Both the reconstructions worked similarly for static knee laxity .  The extra-articular procedure played an important role in better constraining the displacement of lateral tibial compartment , whereas the anatomic double-bundle reconstruction better restored the dynamic behavior of knee joint highlighted under pivot-shift stress test . Study design Case series A total of 108 patients with unilateral instability of the knee , associated with rupture of the anterior cruciate ligament , was prospect ively r and omised for arthroscopic single- or double-bundle reconstruction of the ligament using hamstring tendons . The same post-operative rehabilitation protocol was used for all . The patients were followed up for a mean of 32 months ( 24 to 36 ) . We measured the anterior laxity and joint position sense at different angles of flexion of the knee to determine whether both bundles in the double-bundle reconstruction contributed to the stability of the joint and proprioception . No significant difference was found between the two groups with regard to anterior laxity measured by the KT-2000 arthrometer with the knee at 20 degrees or 70 degrees flexion nor with regard to proprioception . A notchplasty was required less often in the double- compared with the single-bundle reconstruction . We did not find any advantage in a double-bundle as opposed to a single-bundle reconstruction in terms of stability or proprioception Double-bundle  anterior cruciate ligament ( ACL ) reconstruction is intended to replicate the anatomy and the function of the anteromedial and posterolateral bundles of the native ACL to improve patients ' satisfaction and knee stability . We prospect ively assigned 75 consecutive patients with an isolated ACL lesion to one of three sequential groups of 25 patients each . Group I received a single-bundle , single-incision transtibial ACL reconstruction . Groups II and III received a double-bundle reconstruction with a single-incision transtibial technique or a double-bundle , twoincision outside-in technique , respectively . We obtained subjective International Knee Documentation Committee and Knee Injury and Osteoarthritis Outcome Score evaluations and objective International Knee Documentation Committee scores and KT-1000 measurements preoperatively and at followup . All patients reached a minimum followup of 2 years . KT side-to-side difference in Groups I , II , and III were  
    Output:
    
Patient-reported outcome measures and functional outcomes did not differ to a large extent ; however , differences when identified were almost exclusively in favour of double-bundle reconstruction .
Conclusion Based on current evidence , double-bundle reconstruction appears to have fewer re-ruptures and less antero-posterior and rotatory laxity .
Furthermore , no differences were found in short-term patient-reported outcome measures or objective findings .