Search

To determine the functional recovery, active reincorporation, and anteroposterior and rotational stability of patients undergoing anterior cruciate ligament (ACL) reconstruction using arthroscopy techniques with simple-bundle (SB) or double-bundle (DB). The following databases were searched: PubMed, Embase (Elsevier platform), the Cochrane Central Register of Controlled Trials (Wiley platform), Web of Science, and CINAHL. Level I and II studies involving anterior cruciate ligament arthroscopy were included in the search. Records were screened by title and abstract and assessed the risk of bias of selected studies. Meta-analyses using RevMan 5.3 software were conducted on the following outcomes: knee functionality, objective measurements of knee stability, rotational knee stability and knee anterior stability, sports reincorporation, and subjective assessments. Twenty-four studies of patients undergoing ACL reconstruction were included in the qualitative and quantitative synthesis (1707 patients) for Lysholm score, Subjective International Knee Documentation Committee (IKDC) score, Tegner score, KT-1000/2000, Lachman test, Objective IKDC score, and Pivot-Shift test. A return to pre-injury level showed a significant decrease in the Lysholm score (mean difference, - 0.99; 95% CI - 1.71 to - 0.40; P = 0.007) and Tegner score (mean difference, - 0.07; 95% CI, - 0.13 to - 0.01; P = 0.02) at DB reconstruction, similar to the knee functionality outcome of the subjective IKDC score (mean difference - 1.42; 95% CI - 2.46 to - 0.38; P = 0.007). There is no clear or significant difference in clinical stability and knee function or in sports incorporation with the true difference occurring in the subjective assessment., (© 2021. The Author(s).)

Background: Rupture of the anterior cruciate ligament (ACL) is a well-known risk factor for the development of posttraumatic osteoarthritis (PTOA), but patients with the "same injury" can have vastly different trajectories for the onset and progression of disease. Minor subcritical injuries preceding the critical injury event may drive this disparity through preexisting tissue pathologies and sensory changes., Purpose: To investigate the role of subcritical injury on ACL rupture risk and PTOA through the evaluation of pain behaviors, joint mechanics, and tissue structural change in a mouse model of knee injury., Study Design: Controlled laboratory study., Methods: Ten-week-old male C57BL/6J mice were allocated to naïve control and subcritical knee injury groups. Injury was induced by a single mechanical compression to the right hindlimb, and mice were evaluated using joint histopathology, anteroposterior joint biomechanics, pain behaviors (mechanical allodynia and hindlimb weightbearing), and isolated ACL tensile testing to failure at 1, 2, 4, or 8 weeks after injury., Results: Subcritical knee injury produced focal osteochondral lesions in the patellofemoral and lateral tibiofemoral compartments with no resolution for the duration of the study (8 weeks). These lesions were characterized by focal loss of proteoglycan staining, cartilage structural change, chondrocyte pathology, microcracks, and osteocyte cell loss. Injury also resulted in the rapid onset of allodynia (at 1 week), which persisted over time and reduced ACL failure load ( P = .006; mean ± SD, 7.91 ± 2.01 N vs 9.37 ± 1.01 N in naïve controls at 8 weeks after injury), accompanied by evidence of ACL remodeling at the femoral enthesis., Conclusion: The present study in mice establishes a direct effect of a single subcritical knee injury on the development of specific joint tissue pathologies (osteochondral lesions and progressive weakening of the ACL) and allodynic sensitization. These findings demonstrate a predisposition for secondary critical injuries (eg, ACL rupture) and an increased risk of PTOA onset and progression (structurally and symptomatically)., Clinical Relevance: Subcritical knee injuries are a common occurrence and, based on this study, can cause persistent sensory and structural change. These findings have important implications for the understanding of risk factors of ACL injury and subsequent PTOA, particularly with regard to prevention and management strategies following an often underreported event.

Objective: The purpose of this study was to determine the effects of lower extremity motor control exercises on knee proprioception, muscle strength, and functional level in patients with anterior cruciate ligament reconstruction (ACL-R)., Materials and Methods: Thirty-two of the 57 patients with ACL-R using tibialis anterior allografts were divided into two groups. Group I: lower extremity motor control exercises were added to the standard rehabilitation program. Group II: standard rehabilitation program was applied. Effects of lower extremity motor control exercises on quadriceps and hamstring muscles strength, knee joint position sense, and hop test were evaluated., Results: There were no differences in muscle strength and endurance of the quadriceps and hamstring between the operative and nonoperative sides in Group I ( p > 0.05) while there were significant differences in strength of the quadriceps and hamstring between the operative and nonoperative sides in Group II ( p < 0.05). There were significant differences in the endurance of the quadriceps and hamstring and knee joint position sense at 15°, 45°, and 75° between the operative sides of the patients in both groups ( p < 0.05)., Conclusions: The neuromuscular control exercises program was found to be more effective in reducing the difference in strength while the standard program was found to be more effective in reducing the difference in endurance between the operated knee and the other knee. This study revealed that neuromuscular control exercises should also be used to improve knee proprioception sense following ACL-R., Competing Interests: All authors have no conflicts of interest with respect to the data collected and procedures used within this study., (Copyright © 2019 Defne Kaya et al.)

Objective: The objective was to compare muscle activation and knee mechanics during gait between participants with non-traumatic knee osteoarthritis (OA), post-traumatic knee OA, and healthy adults., Design: Participants with non-traumatic knee OA (n = 22), post-traumatic knee OA (n = 19), and healthy adults (n = 22) completed gait trials for this observational, cross-sectional study. Post-traumatic OA group had a history of traumatic anterior cruciate ligament (ACL) rupture. Surface electromyography (EMG) measured activation of seven lower extremity muscles. Motion capture cameras and force plates measured motion and force data. Principal component analysis (PCA) determined waveform characteristics (principal components) from EMG, knee angle, and knee external moment waveforms. Analysis of variance (ANOVA) examined group differences in principal component scores (PC-scores). Regression analyses examined if a variable that coded for OA group could predict PC-scores after accounting for disease severity, alignment, and lateral OA., Results: There was lower gastrocnemius EMG amplitudes (P < 0.01; ANOVA) in the post-traumatic OA group compared to healthy group. Non-traumatic OA group had higher vastus lateralis, vastus medialis, and rectus femoris EMG compared to post-traumatic OA group (P = 0.01 to 0.04) in regression analyses. Also, non-traumatic OA group had higher and prolonged lateral hamstring EMG compared to healthy (P = 0.03; ANOVA) and post-traumatic OA (P = 0.04; regression) groups respectively. The non-traumatic OA group had lower knee extension (P < 0.05) and medial rotation (P < 0.05) moments than post-traumatic and healthy groups., Conclusions: Muscle activation and knee mechanics differed between participants with non-traumatic and post-traumatic knee OA and healthy adults. These OA subtypes had differences in disease characteristics that may impact disease progression., (Copyright © 2019 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Little effort has been directed towards the consequence of an injury on joint angular velocity. We hypothesized that the magnitude of knee joint angular velocity would be decreased after injury. Four injury groups were investigated in an ovine model: (1) anterior cruciate ligament (ACL) and medial collateral ligament (MCL) transection (ACL/MCL Tx) (n = 5), (2) lateral meniscectomy (Mx) (n = 5), (3) partial ACL transection (p-ACL Tx) (n = 5), and (4) partial-ACL and MCL transection (p-ACL/MCL Tx) (n = 5). The magnitude of the angular velocities decreased in the subjects of all groups at multiple points of the gait cycle. The maximum angular velocities during stance and the maximum extension angular velocities during swing were decreased in 15/20 and 17/20 subjects, respectively. There were strong correlations between morphological osteoarthritis scores and the reduction in the maximum extension angular velocities during swing 40 weeks post-p-ACL Tx and 20 weeks post-ACL/MCL Tx. There was no correlation between the decrease of the angular velocity and morphological osteoarthritis scores in the Mx group and the p-ACL/MCL Tx group. The reduction in angular velocity may be a helpful addition as a surrogate measure of OA risk after ACL injury, and could have clinical significance after further investigation in humans.

Background: Combined rupture of the anterior cruciate ligament (ACL) and patellar tendon (PT) is a rare injury pattern. Currently, little evidence exists to help guide management decisions for these patients., Methods: A systematic literature search was conducted using PubMed (MEDLINE) and Scopus (EMBASE and MEDLINE) for all articles reporting on combined rupture of the ACL and PT. The characteristic injury mechanisms, common presentation findings, and outcomes of simultaneous and staged treatment strategies were determined to provide guidance for the management of this uncommon injury pattern. An additional case report from our institution is also reported., Results: Overall, 17 studies met the inclusion criteria and were included in our qualitative review. The mean age at injury was 30 years (range, 15-50 years). A high-energy injury with a rapid deceleration event through a flexed knee on a fixed foot is commonly described as the mechanism of injury. Anterior cruciate ligament rupture was missed on initial clinical examination in 24.1% compared with 17.2% for PT rupture. Injuries to the medial collateral ligament and menisci occured in 65.5% of cases. Outcome scores were reported in 41.4% (12/22) of patients undergoing staged or simultaneous repair. The Lysholm score postoperatively was 96 ± 3.3 for the staged group compared with 85.3 ± 18.6 for simultaneous repair. There were no clear differences between range of motion, time to return to sport, and complication rates between the groups., Conclusions: A high index of suspicion is required to detect concomitant ACL injuries when assessing high-energy PT ruptures. Simultaneous or staged protocols to address both injuries are safe and effective management strategies for this rare combined injury pattern., Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Our previous studies used tibial compression overload to induce anterior cruciate ligament (ACL) rupture in mice, while others have applied similar or greater compressive magnitudes without injury. The causes of these differences in injury threshold are not known. In this study, we compared knee injury thresholds using a "prone configuration" and a "supine configuration" that differed with respect to hip, knee, and ankle flexion, and utilized different fixtures to stabilize the knee. Right limbs of female and male C57BL/6 mice were loaded using the prone configuration, while left limbs were loaded using the supine configuration. Mice underwent progressive loading from 2 to 20 N, or cyclic loading at 9 N or 14 N (n = 9-11/sex/loading method). Progressive loading with the prone configuration resulted in ACL rupture at an average of 10.2 ± 0.9 N for females and 11.4 ± 0.7 N for males. In contrast, progressive loading with the supine configuration resulted in ACL rupture in only 36% of female mice and 50% of male mice. Cyclic loading with the prone configuration resulted in ACL rupture after 15 ± 8 cycles for females and 24 ± 27 cycles for males at 9 N, and always during the first cycle for both sexes at 14 N. In contrast, cyclic loading with the supine configuration was able to complete 1,200 cycles at 9 N without injury for both sexes, and an average of 45 ± 41 cycles for females and 49 ± 25 cycles for males at 14 N before ACL rupture. These results show that tibial compression configurations can strongly affect knee injury thresholds during loading., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background/objective: The menisci of the mammalian knee joint balance the incongruence between femoral condyle and tibial plateau and thus menisci absorb and distribute high loads. Degeneration processes of the menisci lead to pain syndromes in the knee joint. The origin of such degenerative processes on meniscal tissue is rarely understood and may be described best as an imbalance of anabolic and catabolic metabolism. A standardized animal model of meniscal degeneration is needed for further studies. The aim of the current study was to develop a porcine animal model with early meniscal degeneration., Material and Methods: Resection of the anterior cruciate ligament (ACLR) was performed on the left knee joints of eight Göttingen minipigs. A sham operation was carried out on the right knee joint. The grade of degeneration was determined 26 weeks after the operation using histology and magnetic resonance imaging (MRI). Furthermore, the expression of 14 genes which code for extracellular matrix proteins, catabolic matrix metalloproteinases and inflammation mediators were analyzed., Results: Degenerative changes were detected by a histological analysis of the medial meniscus after ACLR. These changes were not detected by MRI. In terms of their gene expression profile, these degenerated medial menisci showed a significantly increased expression of COL1A1., Conclusion: This paper describes a new animal model for early secondary meniscal degeneration in the Göttingen minipig. Histopathological evidence of the degenerative changes could be described. This early degenerative changes could not be seen by NMR imaging.

Objective: To evaluate the clinical effects of arthroscopic reconstruction of anterior cruciate ligament (ACL) and minimally invasive reconstruction of posteromedial corner (PMC)., Methods: There were 22 cases of ACL and PMC tear were performed with reconstruction from March 2012 to February 2014. The patients were 29.4 years old on average, including 8 males and 14 females. ACL reconstruction was performed under arthroscopy and PMC reconstruction was performed minimally invasively through the ACL incision. The stability of knee was assessed by anterior drawer test,Lachman test,vulgus stress test and Slocum test. The function of knee was assessed by Lysholm score and Tegner activity rating. MRI of knee was checked 12 months after operation., Results: The stability tests of all patients were negative at 2 and 6 months after operation, and there was one positive case in anterior drawer test and another positive case in vulgus stress test at 12 months after operation. Lysholm score of all patients 12 months after operation was 96.8 +/- 6.8, which was significantly better than 32.0 +/- 11.2 before operation. Tegner activity rating of all patients at 12 months postoperatively was 6.1 +/- 0.9, which was significantly better than 0.9 +/- 0.5 before operation. It showed the grafts were very well in the MRI 12 months postoperatively., Conclusion: Arthroscopic ACL reconstruction and minimally invasive PMC reconstruction can restore the stability of knee.

Background: Open-wedge high tibial osteotomy is considered to be an effective treatment for medial compartmental osteoarthritis. It is generally admitted that tibial slope increases after open-wedge high tibial osteotomy and decreases after closing-wedge high tibial osteotomy. Young patients with anterior cruciate ligament (ACL) deficiency along with medial compartment osteoarthritis need a combined procedure of ACL reconstruction along with high tibial osteotomy to regain physiological knee kinematics and to avoid chondral damage., Materials and Methods: We retrospectively analysed data from 30 patients who underwent arthroscopic ACL reconstruction along with medial opening-wedge osteotomy from Jan 2004 to June 2012 with a minimum follow up of 2 years. The pre-operative and post-operative posterior tibial slopes were measured. Functional outcome was analysed using clinico-radiological criteria, IKDC scoring and Lysholm score., Results: Post-operative patients improved both clinically and functionally. The patients who had posterior tibial slope >5° decrease, compared to patients who had less <5° decrease, had better functional scores (IKDC and Lysholm score), which was statistically significant (p < 0.05)., Conclusion: Our study has shown that decreasing the tibial slope >5° compared to pre-operative value has functionally favourable effect on the reconstructed ACL graft and outcome. It is known that increasing slope causes an anterior shift in tibial resting position that is accentuated under axial loads. This suggests that decreasing tibial slope may be protective in an ACL deficient knee. Hence by placing the tricortical graft posterior to midline in the opening wedge reduces the posterior tibial slope and thereby reduces the stress on the graft leading to better functional outcome.

Purpose: Knee function, whether anterior cruciate ligament (ACL)-deficient or ACL-reconstructed, is related to many conditions, and no single biomechanical variable can be used to definitively assess knee performance. The purpose of this study was to investigate the relationship between extension and flexion muscle strength and knee function in patients prior and following ACL reconstruction., Methods: 44 ACL-deficient patients with a mean age of 26.6 years were tested between 3 and 6 months following an acute injury and 2 years following ACL reconstruction. All reconstructed patients underwent surgical reconstruction within 6 months of ACL injury using bone-patellar tendon and interference screws. The Cincinnati knee rating system was used to assess knee function. Muscle strength was assessed with the Biodex™ Dynamometer. Isokinetic concentric and eccentric flexion and extension peak torque (Nm/kg) was tested at three different speeds: 60°/s, 120°/s and 180°/s. Isometric strength was tested in 30° and 60° of knee flexion. Both the involved and non-involved legs were tested to calculate symmetry indices., Results: The mean Cincinnati score in the ACL-deficient patient was 62.0 ± 14.5 (range 36-84) and increased to 89.3 ± 9.5 (range 61-100) in the ACL-reconstructed patient. Significant relationships between knee function and muscle strength in the ACL-deficient group were observed for knee symmetry indices (r = 0.38-0.50, p = 0.0001-0.05). In the ACL-reconstructed group significant relationships between knee functionality were observed for isometric and isokinetic peak torque of the involved limb (r = 0.46-0.71, p = 0.0001-0.007)., Conclusion: The findings of this study suggest that neither extension nor flexion peak torque were correlates of knee function in the ACL-deficient knee. However, leg symmetry indices were correlated to knee function. In the ACL-reconstructed knee, knee symmetry indices were not related to knee function but extension and flexion isokinetic concentric and isometric peak torque were.

Objective: To evaluate the early clinical effects of arthroscopic treatment for cruciate ligament cysts of the knee., Methods: From September 2008 to January 2014, 23 patients with cruciate cysts were treated with arthroscopic surgery. There were 11 males and 17 females, with an average age of 28.3 years old (ranged, 16 to 56 years old). Twenty patients had injuries on the right knee and 8 patients had injuries on the left knee. Eight patients had a history of injury,5 patients had a history of chronic injury,and the other 15 patients had no obvious reasons for the symptom. Before the operation, 24 patients were clearly diagnosed as the cruciate ligament cysts of knee joint,and 4 patients were diagnosed as other problems of the knee, but the diagnosis were corrected after the operation. According to the MRI before the surgery,all the patients could be divided into 3 types: 14 were type I, 6 were type II, 8 were type III. After the operation, the patients were suggested to have a rest for 2 weeks, and take exercises everyday at the same time. The knee range of motion, Lysholm score, International Knee Documentation Committee (IKDC) 2000 subjective score, GLASGOW criteria, and McMurray test, pivot shift test, and anterior drawer test were observed to evaluate clinical results., Results: All the incisions healed at the first stage without complications. Twenty-five patients were followed up, and the duration ranged from 12 to 52 months, with a mean of 26.7 months. Three patients accepted the reconstruction of ACL or tightened elongated ACL using bipolar radio frequency. The Lysholm score increased from preoperative 59.80 +/- 6.58 to 75.32 +/- 6.49 at the latest follow-up; IKDC 2000 score increased from preoperative 65.36 +/- 6.26 to 81.00 +/- 5.76 at the latest follow-up. According to GLASGOW criteria,23 patients got an excellent result and 2 good., Conclusion: It has a satisfactory curative effect on ACL reconstruction using bipolar radio frequency. It has advantages of firm fixation, simple and secure operation as well as quick postoperative recovery. It's very important to check the MRI before operations, and carefully seek the cysts during the operations, avoiding the omission of any cysts,especially the cases of multiple cysts. Finally, patients should take exercises actively after operations.

Background: Recent literature has demonstrated that involvement in pivoting sports at the time of injury, increased posterior-inferior tibial slope (PITS), anterolateral capsular ligament (ALCL) disruptions, and combined lateral meniscal lesions all contribute to a higher grade of pivot shift after acute anterior cruciate ligament (ACL) injuries., Purpose: To identify risk factors associated with grade 3 pivot shift after acute ACL injuries., Study Design: Case-control study; Level of evidence, 3., Methods: A database of patients undergoing primary ACL reconstruction from 2009 to 2015 after acute ACL injuries was retrospectively reviewed. A total of 30 patients (30 knees) with grade 3 pivot shift were identified as the study group. Moreover, 30 patients (30 knees) with grade 1 and 30 patients (30 knees) with grade 2 pivot shift were randomly chosen as the 2 control groups. All pivot-shift tests were performed with the patients under anesthesia. Predictors of grade 3 pivot shift that were explored included patient age, sex, time from injury to surgery, pivoting sports involvement at the time of injury, lateral PITS, medial PITS, ALCL disruptions, preoperative KT-1000 arthrometer side-to-side difference, and combined lateral or medial meniscal lesions. Comparisons were performed between the study group and the 2 control groups. Univariable and multivariable logistic regressions were used to identify independent risk factors that were associated with grade 3 pivot shift., Results: Univariable and multivariable logistic regressions between the study group and the 2 control groups showed that pivoting sports involvement at the time of injury (odds ratio1 [OR1; grade 3 vs grade 1 pivot shift with grade 1 = reference], 11.88; 95% CI, 1.94-149.91; OR2 [grade 3 vs grade 2 pivot shift with grade 2 = reference], 3.41; 95% CI, 1.92-22.60), abnormal degree of lateral PITS (OR1, 14.41; 95% CI, 1.69-174.78; OR2, 6.41; 95% CI, 1.48-47.70), ALCL disruptions (OR1, 8.28; 95% CI, 1.71-117.14; OR2, 4.96; 95% CI, 1.07-28.75), and combined lateral meniscal lesions (OR1, 27.56; 95% CI, 5.48-240.52; OR2, 5.83; 95% CI, 1.21-38.56) were independent risk factors of grade 3 pivot shift after acute ACL injuries., Conclusion: For acute ACL injuries, the best set of predictors of grade 3 pivot shift were pivoting sports involvement at the time of injury, abnormal lateral PITS, ALCL disruptions, and combined lateral meniscal lesions. These results may provide additional information for counseling patients on residual laxity and risks for graft rerupture after ACL reconstruction., (© 2015 The Author(s).)

Background: The ovine stifle joint is an ideal preclinical model to study knee joint biomechanics. Knowledge of the ovine ligamentous and meniscal loading during normal gait is currently limited., Methods: The in vivo kinematics of the ovine stifle joint (N=4) were measured during "normal" gait using a highly accurate instrumented spatial linkage (ISL, 0.3±0.2mm). These motions were reproduced in vitro using a unique robotic testing platform and the loads carried by the anterior/posterior cruciate ligaments (ACL/PCL), medial/lateral collateral ligaments (MCL/LCL), and medial/lateral menisci (MM/LM) during gait were determined., Results: Considerable inter-subject variability in tissue loads was observed. The load in the ACL was near zero at hoof-strike (0% gait) and reached a peak (100 to 300N) during early-stance (~10% gait). The PCL reached a peak load (200 to 500N) just after hoof-strike (~5% gait) and was mostly unloaded throughout the remainder of stance. Load in the MCL was substantially lower than the cruciate ligaments, reaching a maximum of 50 to 100N near the beginning of stance. The LCL carried a negligible amount of load through the entire gait cycle. There was also a major contribution of the MM and LM to load transfer from the femur to the tibia during normal gait. The total meniscal load reached a maximum average between 350 and 550N during gait., Conclusion: Knowledge of joint function during normal motion is essential for understanding normal and pathologic joint states. The considerable variability in the magnitudes and patterns of tissue loads among animals simulates clinical variability in humans., Level of Evidence: III., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Introduction: Anterior cruciate ligament injuries are closely associated with excessive loading and motion about the off axes of the knee, i.e. tibial rotation and knee varus/valgus. However, it is not clear about the 3-D mechanical actions of the lateral and medial hamstring muscles and their differences in loading the ACL. The purpose of this study was to investigate the change in anterior cruciate ligament strain induced by loading the lateral and medial hamstrings individually., Methods: Seven cadaveric knees were investigated using a custom testing apparatus allowing for six degree-of-freedom tibiofemoral motion induced by individual muscle loading. With major muscles crossing the knee loaded moderately, the medial and lateral hamstrings were loaded independently to 200N along their lines of actions at 0°, 30°, 60° and 90° of knee flexion. The induced strain of the anterior cruciate ligament was measured using a differential variable reluctance transducer. Tibiofemoral kinematics was monitored using a six degrees-of-freedom knee goniometer., Results: Loading the lateral hamstrings induced significantly more anterior cruciate ligament strain reduction (mean 0.764 [SD 0.63] %) than loading the medial hamstrings (mean 0.007 [0.2] %), (P=0.001 and effect size=0.837) across the knee flexion angles., Conclusion: The lateral and medial hamstrings have significantly different effects on anterior cruciate ligament loadings. More effective rehabilitation and training strategies may be developed to strengthen the lateral and medial hamstrings selectively and differentially to reduce anterior cruciate ligament injury and improve post-injury rehabilitation., Clinical Relevance: The lateral and medial hamstrings can potentially be strengthened selectively and differentially as a more focused rehabilitation approach to reduce ACL injury and improve post-injury rehabilitation. Different ACL reconstruction procedures with some of them involving the medial hamstrings can be compared to each other for their effect on ACL loading., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: Individuals frequently involved in jumping, pivoting or cutting are at increased risk of knee injury, including anterior cruciate ligament (ACL) tears. We sought to use meta-analytic techniques to establish whether neuromuscular and proprioceptive training is efficacious in preventing knee and ACL injury and to identify factors related to greater efficacy of such programs., Methods: We performed a systematic literature search of studies published in English between 1996 and 2014. Intervention efficacy was ascertained from incidence rate ratios (IRRs) weighted by their precision (1/variance) using a random effects model. Separate analyses were performed for knee and ACL injury. We examined whether year of publication, study quality, or specific components of the intervention were associated with efficacy of the intervention in a meta-regression analysis., Results: Twenty-four studies met the inclusion criteria and were used in the meta-analysis. The mean study sample was 1,093 subjects. Twenty studies reported data on knee injury in general terms and 16 on ACL injury. Maximum Jadad score was 3 (on a 0-5 scale). The summary incidence rate ratio was estimated at 0.731 (95% CI: 0.614, 0.871) for knee injury and 0.493 (95% CI: 0.285, 0.854) for ACL injury, indicating a protective effect of intervention. Meta-regression analysis did not identify specific intervention components associated with greater efficacy but established that later year of publication was associated with more conservative estimates of intervention efficacy., Conclusion: The current meta-analysis provides evidence that neuromuscular and proprioceptive training reduces knee injury in general and ACL injury in particular. Later publication date was associated with higher quality studies and more conservative efficacy estimates. As study quality was generally low, these data suggest that higher quality studies should be implemented to confirm the preventive efficacy of such programs.

Purpose: This mechanical study using an in vitro porcine model compared composite interference screw fixation of soft tissue ACL grafts in tibial tunnels., Methods: Forty-eight porcine profundus tendons and tibiae were divided into four groups of 12 closely matched specimens. Equivalent diameter grafts were assigned to each group. Tibial bone tunnels were drilled to 0.5mm greater than graft diameter. Grafts were fixed in tunnels using one 10 × 35 mm composite interference screw designed by four different manufacturers. Maximal insertion torque and perceived within group mechanical testing outcome predictions were recorded. Constructs were potted and loaded into a six degrees of freedom clamp that placed the servohydraulic device tensile loading vector in direct tunnel alignment. Constructs were pre-loaded to 25 N, pre-conditioned between 0 and 50 N for 10 cycles (0.5 Hz), submaximally tested between 50 and 250 N for 500 cycles (one hertz) and load to failure tested at 20mm/min., Results: Statistically significant differences were not observed between groups for displacement during submaximal cyclic loading, yield load, displacement at yield load, stiffness, ultimate load at failure and displacement at ultimate load. One composite screw group displayed a slightly greater proportion of specimens that required use of more than one screw during insertion., Conclusions: Under highly controlled conditions groups displayed comparable fixation., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The structures in the posterolateral corner of the knee, which stabilize the joint, are often involved in injuries to the posterior cruciate ligament. Familiar structures include the anterior cruciate ligament, posterior cruciate ligament, tibial collateral ligament, and menisci. Less familiar are the structures of the posterolateral corner, the most important of which are the fibular collateral ligament, popliteus tendon, and popliteofibular ligament, which resist varus angulation, external rotation, or posterior translation of the tibia. Injury to the posterolateral corner can be assessed with the posterolateral drawer, dial, reverse pivot shift, external rotation recurvatum, and varus stress tests. The purpose of this review is to highlight the posterolateral corner of the knee and injuries to its structures so that physicians can more accurately diagnose these injuries and provide appropriate treatment. Management focuses on restoring the fibular collateral ligament, popliteofibular ligament, and, in certain cases, the popliteus tendon.

Purpose: The purpose of this study is to determine the difference in the concentrations of testosterone, 17-β estradiol and progesterone between male patients with and without ACL rupture, as well as the possible effect of these hormones on generalized joint laxity., Methods: Male subjects with non-contact knee joint injury were included in this study. Two groups were formed: the examined group, consisting of subjects with ACL rupture and the control group consisting of patients without ACL rupture. After this, the patients from these two groups were paired off on the basis of three factors, level of professional involvement in sports (including the type of sports activity), left or right side of the body and the age of the subjects. In the end, there were 29 pairs (58 subjects). The concentration of sex hormones was determined from saliva specimens with the aid of the Salimetrics enzyme immunoassay. The testing of generalized joint laxity was performed with the aid of the "laxity score" according to Beighton et al., Results: Subjects with ACL rupture have highly statistically significantly greater concentrations of testosterone (p < 0.01), statistically significantly greater concentrations of 17-β estradiol (p < 0.05), and a highly statistically significantly greater generalized joint laxity score than subjects with an intact ACL (p < 0.01)., Conclusion: Increased concentrations of testosterone or 17-β estradiol may be a risk factor leading to ACL rupture. Also, generalized joint laxity may be a factor leading to ACL rupture, but none of the monitored hormones can be set down as the cause of its existence. Young male athletes with higher concentrations of testosterone and greater hyperelasticity should plan preventive programs of physiotherapy for ACL preservation since they present a vulnerable group susceptible to ACL rupture., Level of Evidence: Diagnostic study, Level II.

Background: Despite interventions, anterior cruciate ligament ruptures can cause long-term deficits. To assist in identifying and treating deficiencies, 3D-motion analysis is used for objectivizing data. Conventional statistics are commonly employed to analyze kinematics, reducing continuous data series to discrete variables. Conversely, functional data analysis considers the entire data series., Methods: Here, we employ functional data analysis to examine and compare the entire time-domain of knee-kinematic curves from one-leg hops between and within three groups. All subjects (n=95) were part of a long-term follow-up study involving anterior cruciate ligament ruptures treated ~20 years ago conservatively with physiotherapy only or with reconstructive surgery and physiotherapy, and matched knee-healthy controls., Findings: Between-group differences (injured leg, treated groups; non-dominant leg, controls) were identified during the take-off and landing phases, and in the sagittal (flexion/extension) rather than coronal (abduction/adduction) and transverse (internal/external) planes. Overall, surgical and control groups demonstrated comparable knee-kinematic curves. However, compared to controls, the physiotherapy-only group exhibited less flexion during the take-off (0-55% of the normalized phase) and landing (44-73%) phase. Between-leg differences were absent in controls and the surgically treated group, but observed during the flight (4-22%, injured leg>flexion) and the landing (57-85%, injured leg

Background: Since the 1980's several artificial ligaments were used for reconstruction of the anterior cruciate ligament (ACL) serving different complications. The aim of this study was to assess the clinical and functional outcomes of primary ACL reconstruction using the Ligament Augmentation Reconstruction System (LARS™) with a minimum follow-up of 10-years. The LARS™ presents a synthetic material consisting of non-absorbing polyethylene terephthalate fibres used for ligament reconstruction., Methods: Outcomes of 18 patients who underwent arthroscopic ACL reconstruction using the LARS™ system between 2000 and 2004 with a minimum follow-up of 10 years were observed. The International Knee Documentation Committee score (IKDC), Visual Analog Scale (VAS), Lysholm score, and Tegner Activity Scale were assessed. Clinical assessment was performed by Lachman testing, assessment of side-to-side difference on KT-2000 testing and plain radiography evaluation of osteoarthritis., Results: There were seven males and 11 females, mean age 29 years (range, 18 to 44 years) and a mean follow-up of 151.5 months. Five patients (27.8%) sustained a re-rupture of the LARS™ system and underwent revision surgery after a mean time of 23 months and four patients (22.2%) presented with a re-rupture. The average IKDC score was 76.60 ± 18.18, the average Lysholm score was 88.00 ± 10.07 and the average Tegner activity score was five at final follow-up., Conclusion: Our results indicate that the LARS™ system should currently not be suggested as a potential graft for primary reconstruction of the ACL. In special cases, however, the LARS™ system can serve as an alternative graft., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Purpose: To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee., Methods: Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12)., Results: The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups., Conclusion: Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles., Level of Evidence: Randomised controlled trial, Level II.

Background: The motions causing noncontact anterior cruciate ligament (ACL) injury remain unclear. Tibiofemoral bone bruises are believed to be the result of joint impact near the time of ACL rupture. The locations and frequencies of these bone bruises have been reported, but there are limited data quantifying knee position and orientation near the time of injury based on these contusions., Hypothesis: Knee position and orientation near the time of noncontact ACL injury include extension and anterior tibial translation., Study Design: Descriptive laboratory study., Methods: Magnetic resonance images of 8 subjects with noncontact ACL injuries were acquired within 1 month of injury and were subsequently analyzed. All subjects exhibited bruises on both the femur and tibia in both medial and lateral compartments. The outer margins of bone and the bone bruise surfaces were outlined on each image to create a 3-dimensional model of each subject's knee in its position during magnetic resonance imaging (MRI position). Numerical optimization was used to maximize overlap of the bone bruises on the femur and tibia and to predict the position of injury. Flexion angle, valgus orientation, internal tibial rotation, and anterior tibial translation were measured in both the MRI position and the predicted position of injury. Differences in kinematics between the MRI position, which served as an unloaded reference, and the predicted position of injury were compared by use of paired t tests., Results: Flexion angle was near full extension in both the MRI position and the predicted position of injury (8° vs 12°; P = .2). Statistically significant increases in valgus orientation (5°; P = .003), internal tibial rotation (15°; P = .003), and anterior tibial translation (22 mm; P < .001) were observed in the predicted position of injury relative to the MRI position., Conclusion: These results suggest that for the bone bruise pattern studied, landing on an extended knee is a high risk for ACL injury. Extension was accompanied by increased anterior tibial translation (22 mm), internal tibial rotation (15°), and valgus rotation (5°) in the predicted position of injury relative to the MRI position., Clinical Relevance: This study provides novel data characterizing the motions associated with ACL injury, information critical to improving strategies aimed at injury prevention., (© 2015 The Author(s).)

Purpose: The purpose of this study was to determine the difference in the concentrations of testosterone, 17-β estradiol and progesterone between female patients with and without ACL rupture and the possible effect of these hormones on generalised joint laxity., Methods: Female subjects with non-contact knee joint injury were included in this study. They were divided into two groups: the examined group, consisting of female subjects with ACL rupture, and the control group, consisting of female patients without ACL rupture. In the next step, the patients from these two groups were paired off on the basis of three factors: the level of professional sports involvement (including the type of sports activity), the side of the body where the injury had occurred (left or right) and the age of the subjects. In the end, there were 12 pairs (24 subjects). The concentrations of sex hormones were established from saliva specimens with the aid of the Salimetrics enzyme immunoassay. Generalised joint laxity was tested with the aid of the "laxity score" according to Beighton, Solomon and Soskolne., Results: Female subjects with ACL rupture had significantly lower concentrations of testosterone (p < 0.01), significantly lower concentrations of 17-β estradiol (p < 0.05) and significantly lower concentrations of progesterone (p < 0.01) than female subjects with intact ACL., Conclusions: Decreased concentrations of testosterone, 17-β estradiol or progesterone may be a risk factor leading to ACL rupture. The concentrations of these hormones do not affect generalised joint laxity. Additional research on a larger group of patients is necessary to further determine the effects of these hormones on generalised joint laxity and ACL ruptures. Young female athletes with lower concentrations of sex hormones are more prone to anterior cruciate ligament rupture which is why they need to reduce their sports activities during the pre-ovulatory phase of the menstrual cycle, when these concentrations are additionally reduced.

Hormones such as estradiol have an effect on human connective tissue, making women more susceptible to knee injuries. Indeed, women have a greater risk for non-contact injuries of anterior cruciate ligament (ACL) compared to men when participating in the same sports. The purpose of the present study was to examine the difference in ACL laxity after an eccentric exercise in the lower limbs in young healthy women between oral contraceptive pill (OCP) users and non-OCP users to see the effect of OCP on ACL laxity. Forty young healthy women participated in the experiments (25 with normal menstrual cycle and 15 with taking OCP). ACL laxity and a visual analog pain scale were measured before and after a bout of squat. OCP users had more pain than non-OCP users after heavy exercise (p < 0.001). Both groups showed a significant reduction in ACL laxity on the 2nd day after exercise (p < 0.05). While ACL laxity was always less in the OCP group, when expressed as a percent change from baseline, the ACL laxity change was similar in both groups (p > 0.05). We found that there was no statistically significant difference in ACL laxity recovery over time in response to the delayed onset muscle soreness after a bout of squat between two groups. However, health professionals working with young female adults should recognize that OCP users with less ACL laxity are at higher risk for having knee injuries because of ACL stiffness when doing exercise.

Purpose: To evaluate knee laxity after anatomic ACL reconstruction with additional suture repair of a medial meniscus tear., Methods: Kinematics of the intact knee were determined in 12 human cadaver specimens in response to a 134-N anterior tibial load (aTT) and a combined rotatory load of 10 Nm valgus and 4 Nm internal tibial rotation (aTTPS) using a robotic/universal force moment sensor testing system. Subsequently, the ACL was resected following the creation of a standardized tear of the medial meniscus, a standard meniscus repair and an ACL reconstruction using an anatomic single-bundle (6) or an anatomic double-bundle technique (6). Knee kinematics were determined following every sub-step., Results: Significant increase of aTT in the ACL-deficient knee was found (p ≤ 0.001) with a further increase in the ACL-deficient knee with additional medial meniscal rupture (p ≤ 0.001). ACL reconstructions significantly decreased aTT compared with the ACL and meniscus-ruptured knee. No significant differences were seen between the intact knee and the ACL-reconstructed knee with additional meniscal repair (p < 0.05). In response to a simulated pivot shift, aTTPS in the intact knee significantly increased in the ACL-deficient knee and meniscus-ruptured knee (p = 0.005). No significant differences in knee kinematics were found between SB as well as DB ACL reconstruction with additional medial meniscal repair compared with the intact knee. Comparison of SB versus DB ACL reconstruction did not reveal any significant differences in a simulated Lachman test or simulated pivot shift test (n.s.)., Conclusions: aTT as well as aTTPS significantly increased with ACL deficiency compared with the intact knee; additional medial meniscal rupture further increased aTT. Anatomic ACL reconstruction with medial meniscal repair did not reveal significant differences in knee kinematics compared with the intact knee. Comparison of anatomic SB versus DB ACL reconstruction with additional repair of the medial meniscus did not show significant differences neither in a simulated Lachman nor in a simulated pivot shift test.

Background: ACL reconstruction aims to restore knee function and stability; however, rotational stability may not be completely restored by use of standard intraarticular reconstruction alone. Although individual studies have not shown the superiority of combined ACL reconstruction compared with isolated intraarticular reconstruction in terms of function and stability, biomechanical principles suggest a combined approach may be helpful, therefore pooling (meta-analyzing) the available randomized clinical studies may be enlightening., Questions/purposes: We performed a meta-analysis to determine whether combining extraarticular with intraarticular ACL reconstruction would lead to: (1) similar knee function measured by the IKDC evaluation, return-to-activity, and Tegner Lysholm scores, compared with isolated intraarticular reconstruction; (2) increased stability measured by pivot shift and instrumented Lachman examination; and (3) any differences in complications and adverse events?, Methods: To identify randomized controlled trials (RCTs) comparing combined intra- and extrarticular ACL reconstruction (combined reconstruction) with intraarticular ACL reconstruction only, we searched MEDLINE, EMBASE, SPORTDiscus, Latin American and Caribbean Health Sciences (LILACS), and the Cochrane Central Register of Controlled Trials, and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The main outcomes we sought were patient function and stability and complications after ACL reconstruction. Of 386 identified studies, eight RCTs were included (n=682 participants; followup, 12-84 months; men to women ratio, 2.17:1) in our meta-analysis. Study quality (internal validity) was assessed using the Cochrane risk-of-bias tool; in general, we found a moderate quality of evidence of the included studies., Results: When functional outcomes were compared, we found no difference between patients who underwent intraarticular ACL reconstruction only and those who underwent combined reconstruction (IKDC, return-to-activity, and Tegner Lysholm scores). However, patients who underwent combined reconstruction were more likely to show improved stability based on the pivot shift test (risk ratio [RR], 0.95; 95% CI, 0.91-0.99; p=0.02) and Lachman test (RR, 0.93; 95% CI, 0.88-0.98; p=0.01). In addition, our meta-analysis found no difference between the two treatments in terms of general complications or adverse events (RR, 1.31; 95% CI, 0.70-2.34; p=0.40) and the proportion of patients whose reconstructions failed (RR, 2.88; 95% CI, 0.73-11.47; p=0.13)., Conclusion: Combined intra- and extraarticular ACL reconstruction provided marginally improved knee stability and comparable failure rates but no difference in patient-reported functional outcomes scores. Complications and adverse events such as knee stiffness may be underreported and technical factors such as graft placement were difficult to evaluate. Future studies are needed to determine whether the small differences in additional stability warrant the potential morbidity of the additional extraarticular procedure and to determine long-term failure rates.

Despite general agreement on the effects of knee valgus and internal tibial rotation on anterior cruciate ligament (ACL) loading, compelling debate persists on the interrelationship between these rotations and how they contribute to the multi-planar ACL injury mechanism. This study investigates coupling between knee valgus and internal tibial rotation and their effects on ACL strain as a quantifiable measure of injury risk. Nineteen instrumented cadaveric legs were imaged and tested under a range of knee valgus and internal tibial torques. Posterior tibial slope and the medial tibial depth, along with changes in tibiofemoral kinematics and ACL strain, were quantified. Valgus torque significantly increased knee valgus rotation and ACL strain (p<0.020), yet generated minimal coupled internal tibial rotation (p=0.537). Applied internal tibial torque significantly increased internal tibial rotation and ACL strain and generated significant coupled knee valgus rotation (p<0.001 for all comparisons). Similar knee valgus rotations (7.3° vs 7.4°) and ACL strain levels (4.4% vs 4.9%) were observed under 50 Nm of valgus and 20 Nm of internal tibial torques, respectively. Coupled knee valgus rotation under 20 Nm of internal tibial torque was significantly correlated with internal tibial rotation, lateral and medial tibial slopes, and medial tibial depth (R(2)>0.30; p<0.020). These findings demonstrate uni-directional coupling between knee valgus and internal tibial rotation in a cadaveric model. Although both knee valgus and internal tibial torques contribute to increased ACL strain, knee valgus rotation has the ultimate impact on ACL strain regardless of loading mode., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: Quick changes of direction during running (cutting) are necessary for successful performance of many sports but are associated with noncontact anterior cruciate ligament (ACL) injuries. Currently, it is not known how biomechanics associated with fast performance of cutting tasks relate to the mechanics associated with increased risk for injury. Without this knowledge, the technique emphasized in injury prevention programs may be at odds with the demands of cutting tasks. The purposes of this study were to 1) identify whole body and/or joint mechanics that are related to completion times of 45° and 90° cuts and, from these variables, 2) determine which variables are predictors of performance (i.e., completion time) and/or ACL injury risk (i.e., peak knee adductor moment)., Methods: Whole body and joint biomechanics were analyzed during the execution of two sidestep cutting maneuvers (to 45° and 90°) in 25 healthy experienced soccer players. Pearson correlation coefficients and stepwise multiple regression were used to analyze relations between variables., Results: The variables predictive of 45° cut performance included hip extensor moment and hip sagittal plane power generation as well as medial-lateral center-of-mass to center-of-pressure separation distance. This separation distance was also predictive of peak knee adductor moment. During the 90° cut, medial-lateral ground reaction force impulse and hip frontal plane power generation were predictive of performance whereas hip internal rotation and knee extensor moment were predictive of peak knee adductor moment., Conclusions: These relations have important implications for ACL injury prevention programs. Although restricting frontal and transverse plane movement has been emphasized in many programs, these movement recommendations may not be appropriate for cutting tasks performed at greater angles.

Purpose: The purpose of this study was to examine the effect of changing toe direction on knee kinetics and kinematics associated with anterior cruciate ligament injury during drop vertical jumps., Methods: Fourteen females performed drop vertical jumps under three toe conditions (natural, toe-in, and toe-out). The knee kinetics and kinematics during landing were evaluated using a motion analysis system. Results under three toe conditions were compared using a one-way repeated measures analysis of variance and a post hoc Bonferroni test., Results: Toe-in landing was associated with a significantly greater knee abduction angle, tibial internal rotation angle, and knee abduction moment than the natural and toe-out conditions. Toe-out landing was associated with significantly greater tibial internal rotational angular velocity., Conclusions: Changing toe direction significantly affects knee kinetics and kinematics during landing. It is important to avoid changing toe direction excessively inward or outward during landing to prevent the increases in knee abduction and tibial internal rotation which might increase the risk of ACL injury., Level of Evidence: Prognosis, Level IV.

Purpose: To identify patient concomitant injury and surgical characteristics associated with 6-month excellent functional and isokinetic testing results following anterior cruciate ligament (ACL) reconstruction., Methods: Patients that underwent ACL reconstruction by a single surgeon had isokinetic and functional testing performed with excellent 6-month outcome defined as greater than 85 % in isokinetic strength and 90 % in functional tests (excellent 6-month group vs. delayed 6-month group). Patient concomitant injury and surgical factors were then analysed in univariate and multivariate statistical models to assess which characteristics predicted the excellent 6-month group., Results: The 224 patients included 93 males and 131 females, with median age of 22 (range 12-59) years, body mass index (BMI) of 25.4 (range 17-44), and median Tegner activity score of 6 (range 2-10). Fifty-two patients (23 %) were included in the excellent 6-month group, while 172 patients (77 %) were in the delayed 6-month group. In univariate analysis, favourable factors with the excellent 6-month outcome group were younger age (24 vs. 27; p = 0.01), lower BMI (24.5 vs. 26.2; p = 0.03), and minimal articular cartilage damage (71 vs. 56 %; p = 0.048). In multivariate analysis, a negative effect was observed for patients older than 30 years that had ACL reconstruction with autograft (p = 0.0004)., Conclusion: Factors significantly associated with excellent 6-month functional and isokinetic test results following ACL reconstruction included younger age, lower BMI, and minimal cartilage degeneration. The use of allograft was associated with improved functional and strength testing after ACL reconstruction in patients over 30 years of age., Level of Evidence: Prognostic/therapeutic study, Level III.

Purpose: The purpose of this study was to compare the early functional recovery using biomechanical properties between anterior cruciate ligament (ACL)- and posterior cruciate ligament (PCL)-reconstructed patients and to determine the biomechanical deficit of PCL-reconstructed patients compared to ACL-reconstructed patients., Methods: A motion analysis system was used to measure and calculate kinematic and kinetic data for 10 patients who underwent PCL-reconstructed patients [experimental group (group 1)], 10 ACL-reconstructed patients (group 2), and 10 healthy subjects (group 3) during 45°, 90°, 135°, and 180° cutting and turn running tasks. Groups 1 and 2 were assessed at 3 (return to daily activity) and 6 months (return to light sports) postoperatively., Results: At 3 months postoperatively, compared to groups 2 and 3, group 1 showed a decrease in knee flexion angle, extension moment, valgus moment, external rotational moment, ground reaction force, and increased hamstring-quadriceps ratio. At 6 months postoperatively, results from group 1 resembled those of groups 2 and 3 over time., Conclusions: Patients who underwent PCL reconstruction showed some biomechanical deficits in performance of activities requiring rotation, compared to those who underwent ACL reconstruction. Therefore, the modification of a rehabilitation programme for patients who underwent PCL reconstruction would be necessary for improvement of the biomechanical properties during performance of dynamic activities., Level of Evidence: Case-control study, Level III.

Controversy in management of athletes exists after anterior cruciate ligament (ACL) injury and reconstruction. Consensus criteria for evaluating successful outcomes following ACL injury include no reinjury or recurrent giving way, no joint effusion, quadriceps strength symmetry, restored activity level and function, and returning to preinjury sports. Using these criteria, the success rates of current management strategies after ACL injury are reviewed and recommendations are provided for the counseling of athletes after ACL injury., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Meniscal root tears are an increasingly recognized subset of meniscal injury. The menisci are critical secondary stabilizers of the anterior cruciate ligament (ACL). The kinematic effect of lateral meniscus posterior root tear in the setting of ACL injury is not known., Purpose/hypothesis: The purpose of this study was to determine the effect of tear of the lateral meniscal root on stability of the ACL-deficient knee. The hypothesis was that disruption of the lateral meniscal root will further destabilize the ACL-deficient knee during a simulated pivot shift., Study Design: Controlled laboratory study., Methods: Pivot-shift testing of 8 fresh-frozen cadaveric knees was performed after attachment of photoreflective flags and preparation of CT scans. Each knee was mounted in a custom activity simulator and dynamically loaded from 15° to 90° of flexion with all the permutations of the following: iliotibial band force (50, 75, 100, 125, 150, and 175 N), internal rotation moments (1, 2, and 3 N·m), and valgus moments (5 and 7 N·m). In addition, anterior stability tests were performed by applying a 90-N anterior force to the tibia at flexion angles of 15°, 30°, 45°, 60°, and 90°. During each test, the anterior tibial translation and rotation of the tibia were measured with a high-resolution multiple infrared camera motion analysis system for the following 3 conditions: ACL-intact (ACL-I), ACL-deficient (ACL-D), and ACL-deficient/lateral meniscal posterior root avulsion (ACL-D/LMR-A)., Results: A pivot-shift phenomenon was observed in the ACL-D and ACL-D/LMR-A conditions. The mean tibial translation of the lateral tibial condyle during the pivot-shift maneuver was 2.62 ± 0.53 mm for the ACL-I knees, 6.01 ± 0.51 mm for the ACL-D knees (P value vs. intact: .0005), and 8.13 ± 0.75 mm for the ACL-D/LMR-A knees (P value vs intact: <.0001). During the pivot-shift maneuver, translation was significantly increased in the ACL-D/LMR-A condition compared with the ACL-D condition (P = .0146). Compared with the intact group, anterior tibial translation during the Lachman maneuver also increased at 30° and 90° of flexion in the ACL-D group (P < .0001) and the ACL-D/LM group (P < .0001). No statistically significant difference was found between the ACL-D and ACL-D/LMR-A groups during the Lachman maneuver at 30° and 90° (P = .16 and .72, respectively)., Conclusion: A tear of the lateral meniscal posterior root further reduces the stability of the ACL-deficient knee during rotational loading., Clinical Relevance: This study shows that lateral meniscal root injury further destabilizes the ACL-deficient knee and thus advances the concept that the lateral meniscus is a secondary stabilizer of the knee under pivot-shift loading. In the absence of stronger evidence, the study data suggest a rationale for surgical repair of lateral meniscal root tears encountered in the setting of ACL tears., (© 2015 The Author(s).)

In addition to biomechanical disturbances, peripheral joint injuries (PJIs) can also result in chronic neuromuscular alterations due in part to loss of mechanoreceptor-mediated afferent feedback. An emerging perspective is that PJI should be viewed as a neurophysiological dysfunction, not simply a local injury. Neurophysiological and neuroimaging studies have provided some evidence for central nervous system (CNS) reorganization at both the cortical and spinal levels after PJI. The novel hypothesis proposed is that CNS reorganization is the underlying mechanism for persisting neuromuscular deficits after injury, particularly muscle weakness. There is a lack of direct evidence to support this hypothesis, but future studies utilizing force-matching tasks with superimposed transcranial magnetic stimulation may be help clarify this notion., (© 2014 Wiley Periodicals, Inc.)

Background: An anterior cruciate ligament injury may lead to deteriorations in postural stability. The goal of this study was to evaluate postural stability during the transition from double-leg stance to single-leg stance of both legs in anterior cruciate ligament injured subjects and non-injured control subjects with a standardized methodology., Methods: Fifteen control subjects and 15 anterior cruciate ligament injured subjects (time after injury: mean (SD)=1.4 (0.7) months) participated in the study. Both groups were similar for age, gender, height, weight and body mass index. Spatiotemporal center of pressure outcomes of both legs of each subject were measured during the transition from double-leg stance to single-leg stance in eyes open and eyes closed conditions. Movement speed was standardized., Findings: The center of pressure displacement after a new stability point was reached during the single-leg stance phase was significantly increased in the anterior cruciate ligament injured group compared to the control group in the eyes closed condition (P<.001). No significant different postural stability outcomes were found between both legs within both groups (P>.05). No significant differences were found during the transition itself (P>.05)., Interpretation: The anterior cruciate ligament injured group showed postural stability deficits during the single-leg stance phase compared to the non-injured control group in the eyes closed condition. Using the non-injured leg as a normal reference when evaluating postural stability of the injured leg may lead to misinterpretations, as no significant differences were found between the injured and non-injured leg of the anterior cruciate ligament injured group., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Cyclops lesion was previously described as a fibrous lesion with a granulation tissue core originating from the tibial insertion of the anterior cruciate ligament (ACL) graft. Recently, two case reports described inverted cyclops lesions, which originated from the femoral aspect of the ACL. Both cyclops and inverted cyclops lesions are usually associated with a block to knee extension. Here we present a case of an 18-year-old female who developed a painful inverted cyclops lesion originating from the femoral notch above hamstring autograft without restriction to knee range of motion 20 months after arthroscopically assisted ACL reconstruction. The case is followed by literature review on presentation, diagnosis, and treatment of cyclops and inverted cyclops lesions.

Purpose: To describe current evidence on single- and double-bundle anterior cruciate ligament (ACL) reconstruction, in terms of differences in knee kinematics, functional outcomes, patient-reported outcomes and graft failures., Methods: An electronic search was made using PubMed (MEDLINE), EMBASE and Cochrane Library. Studies published from January 1995 to August 2011 were included, and an updated search was made in PubMed in July 2012. Therapeutic studies, level of evidence I-III, for isolated primary ACL tears written in English comparing single- and double-bundle reconstruction reporting clinical outcome were included. Quality appraisal based on Cochrane Collaboration's tool for assessing risk of bias was performed., Results: Of 7,154 potentially eligible studies, 60 papers were included (25 randomised controlled trials, 21 prospective comparative studies, 14 retrospective comparative studies), comprising 4,146 patients (2,072 single-bundle, 2,074 double-bundle). Minor differences were found between study types. An analysis of graft failures revealed fewer re-ruptures in double-bundle reconstruction than single-bundle, 19 and 44, respectively. Up to 45 % of the studies reported a superior outcome in double-bundle reconstruction in terms of antero-posterior laxity, measured with the Lachman, anterior drawer, KT-1000/2000 and navigation. Measurements of rotatory laxity revealed superior results in double-bundle reconstruction measured with pivot shift and navigation in 18/42 (8/15 anatomically reconstructed) and 9/20 studies, respectively. 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. However, detailed statistical analyses of the included studies divided into homogeneous groups are needed to avoid reporting bias and to confirm any statistical difference.

Background: Individuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control. Here, we therefore aimed to assess muscular activity during movements often used in ACL-rehabilitation and to characterize associations between deviations in muscular activity and specific altered movement patterns, using and further exploring the previously developed Test for substitution Patterns (TSP)., Methods: Sixteen participants (10 women) with unilateral ACL rupture performed Single and Double Leg Squats (SLS; DLS). Altered movement patterns were scored according to TSP, and Surface Electromyography (SEMG) was recorded bilaterally in six hip, thigh and shank muscles. To quantify deviations in muscular activity, SEMG ratios were calculated between homonymous muscles on injured and non-injured sides, and between antagonistic muscles on the same side. Correlations between deviations of injured/non-injured side SEMG ratios and specific altered movement patterns were calculated., Results: Injured/non-injured ratios were low at transition from knee flexion to extension in quadriceps in SLS, and in quadriceps and hamstrings in DLS. On injured side, the quadriceps/hamstrings ratio prior to the beginning of DLS and end of DLS and SLS, and tibialis/gastrocnemius ratio at end of DLS were lower than on non-injured side. Correlations were found between specific altered movement patterns and deviating muscular activity at transition from knee flexion to extension in SLS, indicating that the more deviating the muscular activity on injured side, the more pronounced the altered movement pattern. "Knee medial to supporting foot" correlated to lower injured/non-injured ratios in gluteus medius (rs = -0.73, p = 0.001), "lateral displacement of hip-pelvis-region" to lower injured/non-injured ratios in quadriceps (rs = -0.54, p = 0.03) and "displacement of trunk" to higher injured/non-injured ratios in gluteus medius (rs = 0.62, p = 0.01)., Conclusions: Deviations in muscular activity between injured and non-injured sides and between antagonistic muscular activity within injured as compared to non-injured sides indicated specific alterations in sensorimotor control of the lower limb in individuals with ACL rupture. Also, correlations between deviating muscular activity and specific altered movement patterns were suggested as indications of altered sensorimotor control. We therefore advocate that quantitative assessments of altered movement patterns should be considered in ACL-rehabilitation.

Background: In recent years, the scientific discussion has focused on new strategies to enable a torn anterior cruciate ligament (ACL) to heal into mechanically stable scar tissue. Dynamic intraligamentary stabilization (DIS) was first performed in a pilot study of 10 patients. The purpose of the current study was to evaluate whether DIS would lead to similarly sufficient stability and good clinical function in a larger case series., Methods: Acute ACL ruptures were treated by using an internal stabilizer, combined with anatomical repositioning of torn bundles and microfracturing to promote self-healing. Clinical assessment (Tegner, Lysholm, IKDC, and visual analogue scale [VAS] for patient satisfaction scores) and assessment of knee laxity was performed at 3, 6, 12, and 24 months. A one-sample design with a non-inferiority margin was chosen to compare the preoperative and postoperative IKDS and Lysholm scores., Results: 278 patients with a 6:4 male to female ratio were included. Average patient age was 31 years. Preoperative mean IKDC, Lysholm, and Tegner scores were 98.8, 99.3, and 5.1 points, respectively. The mean anteroposterior (AP) translation difference from the healthy contralateral knee was 4.7 mm preoperatively. After DIS treatment, the mean 12-month IKDC, Lysholm, and Tegner scores were 93.6, 96.2, and 4.9 points, respectively, and the mean AP translation difference was 2.3 mm. All these outcomes were significantly non-inferior to the preoperative or healthy contralateral values (p < 0.0001). Mean patient satisfaction was 8.8 (VAS 0-10). Eight ACL reruptures occurred and 3 patients reported insufficient subjective stability of the knee at the end of the study period., Conclusions: Anatomical repositioning, along with DIS and microfracturing, leads to clinically stable healing of the torn ACL in the large majority of patients. Most patients exhibited almost normal knee function, reported excellent satisfaction, and were able to return to their previous levels of sporting activity. Moreover, this strategy resulted in stable healing of all sutured menisci, which could lower the rate of osteoarthritic changes in future. The present findings support the discussion of a new paradigm in ACL treatment based on preservation and self-healing of the torn ligament.

Purpose of Review: To review the most recent literature on the epidemiology, diagnosis, treatment, and outcomes of pediatric anterior cruciate ligament injury., Recent Findings: There is an increasing prevalence of anterior cruciate ligament injuries in pediatric and adolescent athletes, and nonoperative management of these injuries results in worse outcomes than surgical reconstruction. Prevention exercise protocols are cost-effective in preventing this injury in adolescent athletes. A number of techniques are currently in practice that address anterior cruciate ligament injuries in the skeletally immature, but there is no consensus on the optimal technique., Summary: The reported clinical outcomes from anterior cruciate ligament reconstruction in young patients are favorable.

Background: The incidence of anterior cruciate ligament (ACL) injuries is two to eightfold greater in female compared with male athletes. Anatomic, hormonal, and neuromuscular factors have been associated with this disparity. This study compared gene expression and structural features in ruptured but otherwise normal ACL tissue from young female and male athletes., Methods: A biopsy sample of ruptured ACL tissue (which would normally have been discarded) was obtained intraoperatively from seven female and seven male athletes (12.7 to 22.6 years old). Each sample was divided into portions for histological and gene expression analyses. Specimens for gene analysis were frozen and ground, and RNA was extracted and purified. Microarray analysis was performed on RNA isolated from four female and three male study participants (13.9 to 18.5 years old) who had a noncontact injury. Genes with an expression level that differed significantly between these female and male athletes were grouped into functionally associated networks with use of IPA software (Qiagen). Three genes of interest were chosen for further validation by RT-qPCR (reverse transcription-quantitative polymerase chain reaction) analysis of the samples from all fourteen patients. Several statistical methods were used to examine sex-related differences., Results: Microarray analysis of the RNA isolated from the ruptured ACL tissue from the female and male athletes identified thirty-two genes with significant differential expression. Fourteen of these genes were not linked to the X or Y chromosome. IPA analysis grouped these genes into pathways involving development and function of skeletal muscle and growth, maintenance, and proliferation of cells. RT-qPCR confirmed significant differences in expression of three selected genes: ACAN (aggrecan) and FMOD (fibromodulin) were upregulated in female compared with male study participants, and WISP2 (WNT1 inducible signaling pathway protein 2) was downregulated. No morphological differences among the ruptured tissue from the various participants were apparent on histological examination., Conclusions: The genes identified in this study as differing distinctly according to sex produce major molecules in the ACL extracellular matrix. Significant upregulation of ACAN and FMOD (which regulate the matrix) and downregulation of WISP2 (which is involved in collagen turnover and production) may account for the weaker ACLs in female compared with male individuals., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose: To summarize and discuss the current knowledge on posterior lateral meniscus root tears., Methods: A comprehensive review of the MEDLINE database was carried out to identify relevant articles using different keywords (e.g. "meniscus root", "root tear", "meniscus avulsion", "radial tear" and "lateral meniscus"). The reference lists of the reviewed articles were searched for additional relevant articles., Results: Posterior lateral meniscus root tears are found in 7-12% of patients with a tear of the anterior cruciate ligament (ACL). Biomechanical studies have found an increase in lateral compartment contact pressure of approximately 50% after creation of a posterior lateral meniscus root tear. There is some evidence that the biomechanical consequences of these injuries are significantly influenced by the presence and integrity of the meniscofemoral ligaments. Clinical studies have found encouraging results after repair of posterior lateral meniscus root tears. Whether root repair can prevent the development of osteoarthritis is currently unknown., Conclusion: A posterior lateral meniscus root tear is a clinical relevant but most likely underrecognized concomitant injury in patients with a tear of the ACL. This article may support clinicians in diagnosing and treating this unique type of meniscus tear., Level of Evidence: V.

Objective: To evaluate knee proprioception in patients with anterior cruciate ligament (ACL) injuries and to assess the effectiveness of an exercise program consisting mainly of proprioception exercises addressing pain, proprioception, and functional status following ACL reconstruction., Materials and Methods: Twenty male patients, diagnosed with unilateral ACL injury and scheduled for reconstruction, participated in the study along with 16 age- and sex-matched healthy volunteers. Arthroscopic reconstruction of the ACL using autologous hamstring tendon was performed in every case by the same surgeon. After the operation, a six-month rehabilitation program was initiated. Knee proprioception, pain, and functional status were evaluated before and six months after the reconstruction. An isokinetic dynamometer was used to evaluate proprioception and a visual analog scale (VAS) and the Tegner Lysholm Knee Scoring Scale were used to evaluate pain and functional status respectively., Results: Preoperative proprioception loss was detected on the patients' injured side when compared to the uninjured side and to healthy volunteers (p = 0.00). A significant improvement was found in pain severity, proprioception, and functional capacity after the postoperative six-month rehabilitation program (p = 0.00)., Conclusion: Preoperative proprioception loss was detected in ACL-injured patients. The rehabilitation program predominantly consisting of proprioception exercises provided considerable improvement on knee proprioception and functional status.

PURPOSE OF THE STUDY Recent trends in the experimental surgical management of a partial anterior cruciate ligament (ACL) rupture in animals show repair of an ACL lesion using novel biomaterials both for biomechanical reinforcement of a partially unstable knee and as suitable scaffolds for bone marrow stem cell therapy in a partial ACL tear. The study deals with mechanical testing of the newly developed ultra-high-molecular-weight polyethylene (UHMWPE) biomaterial anchored to bone with Hexalon biodegradable ACL/PCL screws, as a new possibility of intra-articular reinforcement of a partial ACL tear. MATERIAL AND METHODS Two groups of ex vivo pig knee models were prepared and tested as follows: the model of an ACL tear stabilised with UHMWPE biomaterial using a Hexalon ACL/PCL screw (group 1; n = 10) and the model of an ACL tear stabilised with the traditional, and in veterinary medicine used, extracapsular technique involving a monofilament nylon fibre, a clamp and a Securos bone anchor (group 2; n = 11). The models were loaded at a standing angle of 100° and the maximum load (N) and shift (mm) values were recorded. RESULTS In group 1 the average maximal peak force was 167.6 ± 21.7 N and the shift was on average 19.0 ± 4.0 mm. In all 10 specimens, the maximum load made the UHMWPE implant break close to its fixation to the femur but the construct/fixation never failed at the site where the material was anchored to the bone. In group 2, the average maximal peak force was 207.3 ± 49.2 N and the shift was on average 24.1 ± 9.5 mm. The Securos stabilisation failed by pullout of the anchor from the femoral bone in nine out of 11 cases; the monofilament fibre ruptured in two cases. CONCLUSIONS It can be concluded that a UHMWPE substitute used in ex-vivo pig knee models has mechanical properties comparable with clinically used extracapsular Securos stabilisation and, because of its potential to carry stem cells and bioactive substances, it can meet the requirements for an implant appropriate to the unique technique of protecting a partial ACL tear. In addition, it has no critical point of ACL substitute failure at the site of its anchoring to the bone (compared to the previously used PET/PCL substitute). Key words: knee stabilisation, stifle surgery, ultra-high-molecular-weight polyethylene, UHMWPE, nylon monofilament thread, biodegradable screw, bone anchor.

Arthroscopic anterior cruciate ligament (ACL) reconstruction using tendon grafts is the current gold standard for the treatment of ACL tears in active patients. However, many patients still experience residual knee instability, knee pain and progressive cartilage degeneration following ACL reconstruction. Recent developments in mesenchymal stem cell (MSC)-based approaches for treating musculoskeletal injuries have led to the application of MSCs for enhancing healing after ACL injuries. The purpose of this article is to review recent pre-clinical and clinical studies using MSCs for the enhancement of biologic healing of ACL injuries. Because of the success of pre-clinical studies, MSC-based approaches are now thought to be promising treatment options for enhancing biologic healing of ACL grafts and restoring the functional properties to the levels of the native ACL, and ultimately improving clinical outcomes.

Purpose: Posterior lateral meniscus root tears (PLMRTs) affect the intra-articular pressure distribution in the lateral compartment of the knee. The biomechanical consequences of these injuries are significantly influenced by the integrity of the meniscofemoral ligaments (MFLs). A newly introduced arthroscopic classification system for PLMRTs that takes MFL integrity into account has not yet been clinically applied but may be useful in selecting the optimal method of PLMRT repair., Methods: Prospective ACL reconstruction data were collected. Concomitant injuries of the lateral meniscus posterior horn were classified according to their shape and MFL status. The classifications were: type 1, avulsion of the root; type 2, radial tear of the lateral meniscus posterior horn close to the root with an intact MFL; and type 3, complete detachment of the posterior meniscus horn., Results: Between January 2011 and May 2012, 228 consecutive ACL reconstructions were included. Lateral and medial meniscus tears were identified in 38.2% (n = 87) and 44.7% (n = 102), respectively. Of the 87 lateral meniscus tears, 32 cases had PLMRTs; the overall prevalence of PLMRTs was 14% (n = 32). Two medial meniscus root tears were detected. All PLMRTs were classified according to the classification system described above, and the fixation procedure was adapted to the type of meniscus tear., Conclusion: The PLMRT tear is a common injury among patients undergoing ACL repair and can be arthroscopically classified into three different types. Medial meniscus root tears are rare in association with ACL tears. The PLMRT classification presented here may help to estimate the injury's impact on the lateral compartment and to identify the optimal treatment. These tears should not be overlooked, and the treatment strategy should be chosen with respect to the type of root tear., Level of Evidence: IV.

Purpose: To test if diameter of normal anterior cruciate ligament (ACL) can be measured by ultrasound (US), to see if there is a relationship between smaller ACL diameter and ACL injury, and to assess agreement between radiologists in measuring ACL diameter in cases and matched controls., Materials and Methods: In this ethics committee-approved study, maximum diameter of ACL near tibial insertion site was measured by static and dynamic US study in 25 normal contralateral knees of subjects who suffered noncontact ACL injury and in 25 matched control subjects., Results: ACL was visualized as a thick linear hypoechoic band inserted approximately 11 mm caudal to the tibial plateau and the intercondylar eminence. Maximum diameter of contralateral ACL near tibial insertion site among injured subjects was significantly smaller than in noninjured subjects (0.62 ± 0.07 cm versus 0.81 ± 0.06 cm; P < 0.0001). In the regression analysis, the diameter of ACL near tibial insertion site was found significantly proportional to body weight and not significantly associated to height, gender, and age., Conclusion: Diameter of normal ACL near tibial insertion site can be measured by US and the maximum diameter is significantly smaller among subjects with noncontact ACL injury. US is a promising modality that can be used as an excellent screening test to detect subjects especially aspiring athletes prone to ACL injury. Very strong agreement was observed between radiologists in measuring ACL diameter.

Background: This study compared lower extremity EMG activation and sagittal plane kinematics of subjects at a minimum of 2 years post-successful ACL reconstruction and rehabilitation during instrumented single leg hop testing., Methods: Comparisons were made based on subject responses to the following question, "compared to prior to your knee injury how capable are you now in performing sports activities"? Group 1=very capable, Group 2=capable, and Group 3=not capable. In addition to EMG (1000 Hz) and kinematic (60 Hz) data, subjective knee function, internal health locus of control, sports activity characteristics (intensity, frequency) pre-knee injury, and at follow-up were also compared., Results: Group 3 had lower perceived knee function, decreased perceived sports intensity, and more subjects with decreased sports activity intensity by two levels compared to pre-injury values. Perceived function scores, anterior laxity measurements and grades were similar between groups. During single leg hop propulsion and landing Group 1 (very capable) had greater involved lower extremity gluteus maximus and medial hamstring activation amplitudes than Group 3 (not capable). Perceived sports capability was related to better subjective knee function, and higher perceived sports activity intensity., Conclusion: Neuromuscular compensations suggesting a hip bias with increased gluteus maximus and medial hamstring activation were identified at the involved lower extremity among most subjects who perceived high perceived sports capability compared to pre-injury status. These compensations may be related to a permanent neurosensory deficit, and its influence on afferent pathway changes that influence CNS sensorimotor re-organization., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Anterior cruciate ligament (ACL) reconstruction using a single-bundle transtibial technique can achieve good or excellent results in more than 90% of patients, but anatomical and biomechanical studies have questioned its ability to restore knee function. The purpose of this study was to evaluate clinical and tomographic results (patient satisfaction, knee function, and tunnel location) of patients who underwent transportal or transtibial single-bundle ACL reconstruction., Methods: Seventy-one patients with ACL tears were included. Forty-one patients were treated by the single-bundle transportal technique and 30 patients were treated by the single-bundle transtibial technique. Clinical and tomographic data were analyzed in both groups., Results: After a minimum of 2-year period, the transportal group showed more patients with normal clinical tests than the transtibial group (Lachman [p=0.037], pivot shift [0.00], anterior drawer [0.002]; and arthrometer [0.002] tests). Regarding CT evaluation, transportal and transtibial groups obtained the following femoral central tunnel location (mean [SD]), as percentage: 30 (6.5) and 4.2 (6.4) in high-low axis; and 30.9 (5.9) and 33.2 (4.6) in the deep-shallow axis. Values in the tibial side were, respectively: 38 (6.5) and 46.0 (6.8) in the anterior-posterior axis; and 47.2 (2.5) and 46.9 (2.1) in the medial-lateral axis., Conclusion: CT findings showed that the transportal single-bundle technique positions the ACL tunnel closer to the native ACL footprint in both femur and tibia compared with the transtibial single-bundle technique. Moreover, mild asymptomatic instability and extension deficit were observed more often in the transtibial group., (Copyright © 2014 Elsevier B.V. All rights reserved.)