Lateral Impact Research Articles

Performance evaluation of innovative composite wall system under extreme loads

ABSTRACT Current reports on accidents in urban areas reveal the devastation of boundary walls and the consequent risks to human lives and property damage. The present study proposes to mitigate such risks through the development and application of a robust and shock-absorbent composite wall system to replace the normal concrete wall system. The paper adopted a comprehensive Finite Element (FE) study using ABAQUS and used the three-dimensional validated model to initially evaluate the selected four different innovative wall systems (Polypropylene fibre-reinforced composite, ECC-Concrete, ECC-Rubberised concrete, and Rubberised concrete-Concrete composite walls) to evaluate their structural performances under lateral impact and blast loads. The most suitable composition of the wall system is identified after comparing the impact resistance, blast resistance, and the energy absorption capacity of all the selected wall structures. Then, an optimisation study on the best-performed composite is conducted to propose the most appropriate geometric parameters for the composite wall. ECC-Rubberised concrete composite wall shows the least deflection at the selected magnitudes of impact loads and blast loads compared to the other walls. The energy absorption capacity of the ECC-Rubberised concrete composite wall is the highest among all the walls including the normal concrete wall.

Lateral femoral impaction fractures during an ACL tear extend posteriorly on the weight-bearing area of the tibiofemoral joint.

Posterior elongation of the physiological terminal sulcus (TS) due to lateral femoral condyle impaction fracture (LFC-IF) after an anterior cruciate ligament (ACL) tear could potentially decrease the weight-bearing area of the tibiofemoral joint, decrease the tension on lateral meniscus and cause flattening of the LFC which would influence rotational knee motion and cause anisometry of the lateral and anterolateral stabilizers. Therefore, the purpose of the study was to assess if the LFC-IF elongates the physiological TS posteriorly. One hundred patients magnetic resonance images (MRIs) (75 males, 25 females, mean age 32.2 years, SD = 8.2) were included with a 1:1 ratio between the full-thickness ACL tear group and the control group (patients with knee MRI performed due to other reasons, with no tear of ACL on MRI and negative clinical tests). Two independent raters evaluated the sagittal T1-weighted preselected MRI scans. The principal measurement of interest was the distance from the intersection of the Blumensaat line with subchondral bone to the posterior border of the TS/LFC-IF. The median distance from the Blumensaat line to the posterior border of the TS/LFC-IF was significantly higher in the ACL tear group: 14.3 mm, interquartile range (IQR) = 11.6-16.4 mm versus control group: 12.8 mm, IQR = 9.0-15.0 mm, p = 0.038. Intrarater and inter-rater reliabilities were >0.90. LFC-IF after full-thickness ACL tear significantly elongates the physiological TS in the posterior direction. Level III.

Residual behaviour and damage assessment of UHPC-filled double-skin steel tubular columns after lateral impact

Ultra-high performance concrete (UHPC)-filled double-skin steel tubular (DST) column has great potential to be used in the protective structures. Although its lateral impact behaviour has been well understood, the residual behaviour after lateral impact remains unexplored. As a result, this study extensively investigated the residual behaviour and damage assessment of UHPC-filled DST columns after lateral impact. Firstly, a set of six DST columns were designed and tested under lateral impact, followed by static axial compression. In addition, two intact columns were subjected to static axial compression for comparative analysis. Secondly, the refined finite element models were developed and validated using the current test data, and the impact resistant mechanism of UHPC-filled DST columns with different impact locations was analysed. Thirdly, the suitability of different damage indexes for the damage assessment of impacted UHPC-filled DST columns was evaluated. Two damage indexes, the ratio of mid-height deflection to column height (R1), and the ratio of local deflection to the column diameter (R2), were proposed for the DST columns. Finally, two types of machine learning-based models were developed to predict the impact damage of UHPC-filled DST columns. The prediction models were interpreted locally and globally using the additive feature attribution method Shapley Additive Explanation (SHAP). The machine learning-based prediction models can rapidly evaluate the damage extent of impacted UHPC-filled DST column, which hold great significance for the selection of strengthening and retrofitting schemes.

Investigating the long-term outcomes and efficacy of surgical intervention in patients with adolescent idiopathic scoliosis and Cobb angles ranging between 40 and 50 degrees.

Patients with adolescent idiopathic scoliosis (AIS) are either managed with non-operative strategies or surgery depending on the severity of lateral curvature and impact on quality of life. However, supportive evidence for the appropriate treatment approach is lacking in AIS patients with Cobb angles between 40 and 50 degrees. Therefore, we investigated differences in long-term patient-centered outcomes in AIS patients with Cobb angles between 40 and 50 degrees who received either operative or non-operative management. A total of 919 patients aged 10-21years old with adolescent idiopathic scoliosis and 40-50 degree Cobb angles were identified from the HARMS Study Group (HSG) registry and dichotomized based on operative or non-operative management. Baseline and 2year follow-up SRS-22 scores from these patients were analyzed for significant differences between the total score values, domain values, and the magnitude of score change over time using multiple comparisons analyses. Multivariable regressions adjusting for age, body mass index, location of spinal deformity, and management strategy were also performed. Operative versus non-operative strategy was significantly, independently associated with differences in SRS-22 total and domain scores over time (effect likelihood ratio test, p < 0.03 for all regressions). Operatively managed patients had significantly greater improvement in SRS-22 total and domain scores over the follow-up duration compared to non-operatively managed patients (p < 0.02 for all comparisons). This preliminary analysis suggests that operatively managed patients may have had better long-term outcomes than non-operatively managed patients within this AIS subpopulation. These findings support the need for further prospective investigation to determine the optimal management strategy to improve evidence-based, patient-reported outcomes for AIS patients with Cobb angles between 40 and 50 degrees. Level III.

Biomechanical characteristics of ligament injuries in the knee joint during impact in the upright position: a finite element analysis

BackgroundOur study aims to examine stress–strain data of the four major knee ligaments—the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL)—under transient impacts in various knee joint regions and directions within the static standing position of the human body. Subsequently, we will analyze the varying biomechanical properties of knee ligaments under distinct loading conditions.MethodsA 3D simulation model of the human knee joint including bone, meniscus, articular cartilage, ligaments, and other tissues, was reconstructed from MRI images. A vertical load of 300 N was applied to the femur model’s top surface to mimic the static standing position, and a 134 N load was applied to the impacted area of the knee joint. Nine scenarios were created to examine the effects of anterior, posterior, and lateral external forces on the upper, middle, and lower regions of the knee joint.ResultsThe PCL exhibited the highest stress levels among the four ligaments when anterior loads were applied to the upper, middle, and lower parts of the knee, with maximum stresses at the PCL-fibula junction measuring 59.895 MPa, 27.481 MPa, and 28.607 MPa, respectively. Highest stresses on the PCL were observed under posterior loads on the upper, middle, and lower knee areas, with peak stresses of 57.421 MPa, 38.147 MPa, and 26.904 MPa, focusing notably on the PCL-tibia junction. When a lateral load was placed on the upper knee joint, the ACL showed the highest stress 32.102 MPa. Likewise, in a lateral impact on the middle knee joint, the ACL also had the highest stress of 29.544 MPa, with peak force at the ACL-tibia junction each time. In a lateral impact on the lower knee area, the LCL had the highest stress of 22.279 MPa, with the highest force at the LCL-fibula junction. Furthermore, the maximum stress data table indicates that stresses in the ligaments are typically higher when the upper portion of the knee is affected compared to when the middle and lower parts are impacted.ConclusionsThis study recommends people avoid impacting the upper knee and use the middle and lower parts of the knee effectively against external forces to minimize ligament damage and safeguard the knee.

Residual Load-Carrying Capacity of Hybrid FRP-UHPC-Steel Double-Skin Tubular Column after Lateral Impact

Residual Load-Carrying Capacity of Hybrid FRP-UHPC-Steel Double-Skin Tubular Column after Lateral Impact

Lateral impact performance of pitting corroded CFST columns for offshore applications

This study investigates the lateral impact performance of circular concrete-filled steel tube (CFST) columns with pitting corrosion. A comprehensive set of 15 CFST specimens was meticulously constructed, including 3 non-corroded specimens used as controls and 12 specimens subjected to varying pitting corrosion conditions. These conditions included different depths, numbers of corrosion pits, and pitting corrosion distributions. Additionally, an extensive Finite Element Analysis (FEA) was conducted to gain detailed insights into the instantaneous dynamic responses of CFST columns with pitting corrosion under lateral impact. The FEA included failure mechanism investigation, stress and strain analyses, bending moment responses, strain rate changes, and energy transformations. The experimental and FEA results reveal that pitting corrosion significantly affects the dynamic behavior of CFST columns, demonstrating reductions in impact force and flexural capacity due to pitting corrosion, and highlighting the influence of corrosion depth, number of pits, and distribution on column behavior. Finally, a simplified model incorporating the effects of pitting corrosion was proposed to estimate the dynamic flexural strength of pitting corroded CFST columns. The results provide valuable insights for designing and assessing the structural integrity of CFST members in marine environments.

The impact protection behavior of UHPC composite structure on RC columns

In order to prevent the reinforced concrete (RC) structures from being damaged under the overload impact, a new type of composite structure—ultra-high performance concrete (UHPC)–Bio-inspired honeycomb column thin-walled structure (BHTS) was designed in this paper. A scale model with a scaling factor of 1:10 was made. The experimental tests and numerical simulations of RC column and UHPC composite structure were carried out. By comparing the impact force, displacement, shear force, bending moment and energy absorption, the protective effect of the UHPC-BHTS composite structure on RC columns under lateral impact load was evaluated. Then, the failure process of RC column was analyzed, the UHPC-BHTS composite structure absorbed 76.42% of the impact kinetic energy under the higher energy input condition, the shear failure with large damage to the RC column can be converted into bending failure with small damage. At the same time, a new damage assessment method was used to evaluate the RC column. The results show that the RC column with UHPC-BHTS composite structure can effectively protects the RC column structural integrity under impact. The design and modeling methods in this research can provide a useful reference for anti-collision design in practical engineering.

Thin-walled FRP-concrete-steel tubular tower with a top mass block subjected to lateral impact loading: Experimental study and FE analysis

Thin-walled hollow steel tube towers (HSTs), frequently utilized as a wind turbine tower, are facing challenges such as corrosion and local buckling in their service life. To enhance the anti-corrosion capacity and local buckling resistance, an FRP tube and an annular concrete layer can be employed to protect the HST, thus forming a novel member: thin-walled FRP-concrete-steel tubular towers (TW-FCSTs). Using a horizontal vehicle impact system, this study investigated the impact behavior of five large-scale TW-FCSTs, each with a top mass block to mimic the rotor and nacelle of wind turbine. All specimens were designed with a large diameter (300 mm) and a large void ratio (0.73 or 0.82). The experimental results revealed that: (1) Under lateral impact loading, TW-FCSTs displayed a global flexural failure mode, accompanied by localized concavity damage; (2) The inertial effect was enlarged by the top mass block, affecting the dynamic response of TW-FCSTs; (3) the increase of steel thickness led to higher energy dissipation but lower local deformation; (4) the increase of void ratio resulted in larger local deformation but smaller lateral global displacement. Finally, based on LS-DYNA, FE models were utilized to simulate the dynamic responses of TW-FCSTs with a top mass block.

Mechanism and improvement for tail vehicle swaying of power-centralized EMUs

The swing phenomenon of the tail vehicle will reduce the stability of the train operation, and even seriously deteriorate the ride comfort of passengers. In response to the relevant railway department, this paper reported the different dynamics performances in tail vehicle swaying when power-concentrated EMUs passed through a tunnel under push/pull operation. To analyze the characteristics and mechanism of the EMU tail swaying, field tests and numerical simulations were conducted. Firstly, through the on-track test, it was found that under push operation, the EMU tail continued to sway at a frequency of 1.3 Hz inside the tunnel, while under pull operation, only a swing of 1.7 Hz appeared at the tunnel entrance. Subsequently, through a simulation analysis, it was found that under push operation, the vortex-induced vibration of the tail carbody occurred inside the tunnel, leading to the sustained swing with a carbody hunting frequency of 1.3 Hz; under pull operation, due to the aerodynamic effect of the tunnel entrance, the secondary lateral stop had an abnormal elastic collision with the bogie frame, and the lateral impact on the bottom of the tail carbody caused a swing of 1.7 Hz, which was verified by the field test. Finally, for the motor vehicle of the EMU tail, two improvement measures of yaw damper optimization were proposed to alleviate the EMU tail swaying inside the tunnel. Furthermore, the research results can provide a reference for the aerodynamic swing problem of other trains, which has certain engineering significance.

Characteristics and control of impact vibration and noise in rail belt conveyor

The rail belt conveyor is an innovative energy-saving belt conveyor. Revolutionizing the traditional roller support, it utilizes interval-spaced carriages to support the conveyor belt. The study of impact vibrations in rail belt conveyors remains underexplored in current research. This paper investigates the impact vibration and noise characteristics of the wheel–rail-steel structure coupling system, as well as their control and optimization strategies. First, vibration and noise measurements were conducted along the track. Results indicate that impact vibrations and noise originating from expansion joints and inserted joints fall within the frequency range of 1.5 kHz–5 kHz. Particularly noteworthy is the pronounced impact noise near inserted joints, with dominant frequencies ranging from 1.5 kHz to 2.5 kHz. Further investigation has revealed that the impacts on inserted joints encompass interactions between the wheel and rail, as well as between different sections of the rail itself. Next, the characteristics of filler materials such as polyurethane rubber, silicone, polyurethane resin, and epoxy resin were analyzed and compared. The experimental results show that filling rubber in expansion joints can reduce lateral impact vibrations by 61% and vertical impact vibrations by 66%. Additionally, the sound pressure level was reduced by approximately 1.7 dBA. Finally, welding the guiding rail to its preceding rail and grinding the welded surface effectively eliminated the composite impact vibrations and sharp noise at the inserted joint, resulting in a decrease of approximately 3 dBA in the sound pressure level. This paper provides guidance on the structural improvement and acoustic optimization of rail belt conveyors.

Numerically efficient analysis of FRP confined CFST members under lateral low-velocity impact loading

Numerically efficient analysis of FRP confined CFST members under lateral low-velocity impact loading

ASSESSMENT OF LATERALIZATION AND HANDWRITING QUALITY IN YOUNG ELEMENTARY SCHOOL STUDENTS

Dominant lateralization refers to the phenomenon of having a leading extremity or leading sense during the execution of complex psychomotor activities. Writing represents a complex human ability and simultaneously the most complex form of linguistic activity, which includes knowledge, skills, and the art of proper letter formation. This study explores the relationship between lateralization and handwriting quality with the aim of identifying children with dysgraphic handwriting. The sample consisted of 90 younger elementary school students (third, fourth, and fifth grade), aged 8 to 11 years (AS = 9.93; SD = 0.84), of both genders (46 boys and 44 girls). The Handwriting Dysgraphia Assessment Test was used to assess handwriting quality. Dominant upper extremity lateralization was assessed using tests from the Sovak Test Battery (1979), while visual lateralization was assessed using a test from the General Defectology Diagnostics Practicum. The research was conducted at an elementary school in Trebinje, during February and March 2024. Research results show that a significant percentage of younger elementary school children have dysgraphic (21.1%) or severely dysgraphichandwriting (35.6%). Among the majority of participants, right-handed upper extremity dominance was observed (86.7%) along with right visual dominance (82.2%), with coordinated visual and upper extremity lateralization present in 88.9% of children. The results of investigation of the impact of uncoordinated upper extremity and visual lateralization on dysgraphic handwriting did not demonstrate statistical significance. Although our results did not confirm a link between lateralization and handwriting quality, for younger elementary school children with uncoordinated upper extremity and visual lateralization, exercises focusing on directing, practicing, and stabilizing lateralization are recommended.

Investigation of high-performance alkali-activated slag concrete-filled steel tubular members under lateral impact

This paper studied the behaviour of High-performance Alkali-activated slag Concrete-Filled Steel Tubular members under transverse impact along with axial compression. Combining alkali-activated slag concrete with concrete-filled steel tubes provides a novel composite material incorporating the benefits of alkali-activated slag concrete and steel tubes. Alkali-activated slag concrete, known for its environmentally beneficial traits compared to traditional concrete, improves sustainability, while concrete-filled steel tube increases structural stability. Seven specimens composed of one hollow tube and six high-performance alkali-activated slag concrete-filled steel tubular specimens were tested using a drop hammer test setup to enhance our understanding of the structural performance of high-performance alkali-activated slag concrete-filled steel tubular members. A finite element analysis model was then established to broadly compare the impact resistance of circular high-performance alkali-activated slag concrete-filled steel tubular members. The mid-span displacement and impact test durations of specimens subjected to lateral impact and axial compression were assessed using a high-speed video camera called Phantom V411. This analysis includes the examination of maximum impact load, impact plateau value, maximum displacement, residual displacement, indentation, impact duration and strain responses, and an investigation into the failure modes of the specimens. The obtained results closely align with the experimental outcomes, indicating the effectiveness of the FEA model in predicting the behaviour of circular high-performance alkali-activated slag concrete-filled steel tubular members.

Calculation of Lateral Logging Response and Environmental Impact Factor Analysis for Small Borehole Array

This paper refines an optimized array lateral logging tool designed for small boreholes, leveraging existing technologies. The tool features four investigation depth curves, and resistivity response curves are derived through finite element model simulations considering variables such as borehole size, mud characteristics, invasion zone features, resistive annuli, formation rock properties, and formation resistivity anisotropy. The findings included the following: (1) Increasing the wellbore diameter uniformly decreased resistivity across all four investigation depths, positively correlating with borehole size. When mud resistivity (Rm) exceeded formation resistivity (Rt), resistivity curves became distorted. (2) For high- and low-invasion models, the ratio of the deepest to the shallowest investigation depth curves ranged from 1 to 8 and 0.6 to 0.9, respectively, with maximum separation at an invasion depth of 0.5–0.8 m. (3) Under invasion conditions with annuli, an invasion zone depth and annulus width around 0.4 m yield well separated the resistivity curves for all depths. Low- and high-resistivity annuli of 2 m and 0.7 m, respectively, can cause curve intersections. (4) When the formation thickness exceeded 0.2 m, the tool accurately reflected formation resistivity variations and demonstrated effective layer identification in multi-layer conditions. (5) In anisotropic formations, resistivity was negatively correlated with the anisotropy coefficient (λ) as it changed from 2 to 4. The instrument can be fully utilized in the exploration of thin interlayers in oil and gas, significantly enhancing the accuracy of resource identification and extraction technologies.

Comparative study on the impact behaviors of CFWST columns reinforced with steel spiral and tube

To obtain superior corrosion resistance and impact resistance, as well as good economic benefits, two new types of composite structure called as steel tube internally-reinforced concrete-filled weathering steel tube (STRCFWST) and steel spiral internally-reinforced concrete-filled weathering steel (SSRCFWST) columns are proposed and compared in terms of their impact resistance in this paper. Eleven impact tests were conducted and three parameters comprising steel spiral diameter, wall thicknesses of outer and inner steel tube were considered to evaluate their influences on the lateral impact behaviors. Results show the presence of inner steel tube and reinforcement cage significantly enhances the impact resistance while slightly decreases the energy absorption capacity. Increasing inner steel tube wall thickness helps to improve the impact resistance, however the contribution is not so good as that produced by increasing the outer steel tube wall thickness, whilst varying steel spiral diameter almost has no impact. Numerical models were developed by ABAQUS/Explicit and verified via the test, based on which the full-range behaviors of STRCFWST, SSRCFWST and unreinforced concrete-filled weathering steel tube (CFWST) columns under impact loading were compared and discussed. It is demonstrated that steel tube and reinforcement cage provide little confinement on concrete infill under impact. With the same internal steel ratio, inner steel tube makes a greater contribution to sectional bending moment resistance and energy absorption as compared to the reinforcement cage.

Energy absorption of foam-filled TPMS-based tubular lattice structures subjected to quasi-static lateral crushing

Aluminium foam and TPMS-based tubular lattice structures (T-TLS) were of interest due to their superior energy absorption capabilities and inherent lightweight characteristics. However, their synergistic functionality in a composite form remained unexplored. In pursuit of augmenting the crashworthiness characteristics, aluminum foam was filled into T-TLS to form foam-filled T-TLS. FE models were established and validated using lateral crushing experiments. Foam-filled T-TLS exhibited higher energy absorption (EA) compared to the sum of empty T-TLS and foam filler, primarily attributed to the interaction between T-TLS and foam filler. Compared to single circular filled tubes (SCFT) with the same outer sizes and mass, foam-filled T-TLS revealed markedly enhanced crashworthiness, with EA and SEA values being 3.5–3.9 times and 4.0–4.7 times that of SCFT, respectively. Subsequently, parametric investigations underscored the evident influences of relative densities of T-TLS and foam filler, tube thickness and diameter on crashworthiness of foam-filled T-TLS. Finally, a multi-objective optimization was performed to derive optimized configurations by using non-dominated sorting genetic algorithm II (NSGA-II) and radial basis function (RBF) metamodels. In comparison with the baseline designs, the optimal results demonstrated significant enhancements in crashworthiness, with SEA increasing by 173.3 to 206.6 %. The present work provided a new paradigm in the design and development of advanced energy absorbers characterized by high-efficiency energy dissipation under lateral impact scenarios.

Experimental and numerical study on influence of impact mass and velocity on failure mode of RC columns under lateral impact

Reinforced concrete (RC) structures may encounter impact loads during service life, such as vehicle collisions, ship strikes, and explosions. Limited existing impact tests on RC columns and piers have yet to fully reveal the column impact performance and its relationship with structural or load parameters. To explore the effects of impact mass and velocity, which determine the impact energy, on the impact performance of RC columns, pendulum impact tests on nine RC columns were performed utilizing a specially designed loading setup. The test variables included the impact mass and velocity of the pendulum, as well as the slenderness ratio and stirrup ratio of the columns. During the tests, the impact force and velocity of the pendulum, as well as the axial force, displacement, and acceleration of the columns, were measured. Additionally, the damage evolution of each specimen was recorded using a high-speed camera. One-side shear failure, two-side shear failure near the impact point, and shear failure at the column bottom end were observed during the tests. The results indicated that, under similar impact energy, as the impact velocity increased, the specimens with the low stirrup ratio transitioned from one-side shear failure to two-side shear failure. An enhancement in the impact resistance of the columns was observed when the stirrup ratio was increased, or the slenderness ratio decreased. For the enhanced columns, shear failure was avoided at lower impact velocities; however, at the maximum impact velocity, end shear failure or one-side shear failure yet occurred. Additionally, a parametric analysis using LS-DYNA finite element software further clarified the effects of impact velocity and mass on the dynamic response and failure mode of RC columns.

Pedestrian-ground contact injury protection method under the constraint of the vehicle-front end shape and its robust analysis

This research paper introduces a novel approach for protecting pedestrians from ground contact injuries through incorporating vehicle front-end shape constraints in the braking control method. The feasibility of the proposed method is evaluated through simulations, and its resilience to different disturbances is studied. Results indicate that the proposed method effectively manages vehicle movement by monitoring the first head-vehicle contact time (t1 ) between the pedestrian’s head and the vehicle. The simulations show that the proposed method reduces ground-related Weighted Injury Cost (WIC) by up to 84%, and the proportion of ‘safe’ mechanisms increases to 74%. The robustness of the braking control method is also evidenced by its high performance during disturbances such as changes in friction coefficient, lag time, and t1 . Furthermore, the anti-disturbance abilities of each vehicle shape are comparable except for t1 disturbance. There are no significant variations in the braking control protection effect between different friction coefficients and each t1 , but noticeable differences exist between lag times. Further analysis reveals that parameter disturbances affect the deceleration of the vehicle and the impact speed of the pedestrian and vehicle, leading to changes in the Vz (Vertical head-to-ground impact velocity), thorax acceleration, pelvic lateral impact force, and knee lateral bending angle, which subsequently increases the risk of pedestrian ground contact injuries. The proposed method offers an efficient solution for protecting pedestrians from ground contact injuries by controlling vehicle braking, highlighting its practical utility.

Outcomes After Single-Stage Anatomic Multiligament Knee Reconstruction With Early Range of Motion in Adolescents.

Multiligament knee injuries (MLKI), rare in adolescents, are challenging injuries that require complex surgical reconstruction. Historically, nonanatomic reconstructions have been associated with prolonged immobilization and failure to restore normal knee biomechanics, resulting in arthrofibrosis and high rates of graft failure. To describe the clinical and patient-reported outcomes (PROs) for adolescent patients treated with single-stage anatomic multiligament knee reconstruction. Case series; Level of evidence, 4. A single-center retrospective study was performed of patients ≤18 years old who underwent reconstruction of MLKIs by a single surgeon between 2014 and 2019 using a single-stage anatomic technique, with protected weightbearing and early range of motion. Complications were defined as infection, arthrofibrosis, deep vein thrombosis (DVT) or pulmonary embolus, and secondary surgery. PROs, including the pediatric version of the International Knee Documentation Committee (Pedi-IKDC) and the Tegner activity score, were obtained at a minimum of 2 years postoperatively. Included were 30 patients (21 male, 9 female; mean age, 15.4 years). The most common ligamentous reconstruction types were anterior cruciate ligament (ACL) + fibular collateral ligament (12 patients; 40%) and ACL + medial collateral ligament (9 patients; 30%). Three patients (10%) had secondary surgeries, including irrigation and debridement of a granuloma, a staged osteochondral allograft transplantation to a lateral femoral condyle impaction fracture, and repair of a medial meniscal tear and lateral femoral condyle fracture associated with new injuries 2 years after ACL + fibular collateral ligament reconstruction. Two patients (7%) developed arthrofibrosis and 1 patient (3%) developed DVT. PRO scores obtained at a mean of 37 months postoperatively included a mean Pedi-IKDC of 87 (range, 52-92) and a median highest Tegner score at any point postoperatively of 9 (range, 5-10). Of the patients who were athletes before their injury, 70% returned to the same or higher level of sport postoperatively. Reconstruction of MLKI in this series of adolescents with single-stage anatomic techniques and early range of motion resulted in low rates of secondary surgery, few complications, and good knee function as well as PRO scores at mean 3-year follow-up.