Knee Biomechanics Research Articles

Sex-specific knee biomechanics in persons with and without knee osteoarthritis: a systematic review and meta-analysis

Sex-specific knee biomechanics in persons with and without knee osteoarthritis: a systematic review and meta-analysis

Anatomical Landmark Technique for Femoral Tunnel Placement of Lateral Extra-Articular Tenodesis

The anterolateral ligament is a crucial part of the anterolateral complex of the knee, providing rotator stability to the knee and being a primary restraint to tibial internal rotation. Lateral extra-articular tenodesis added to anterior cruciate ligament reconstruction can reduce pivot shift without sacrificing the range of motion or increasing the risk of osteoarthritis. A 7- to 8-cm longitudinal skin incision is made and a 9.5- to 10-cm × 1- cm wide iliotibial band graft is dissected, leaving the distal attachment intact. The free end is whip stitched. One of the most important steps during the procedure is the identification of the site of attachment of the iliotibial band graft. The leash of vessels, fat pad, lateral supracondylar ridge, and fibular collateral ligament serve as important landmarks. The tunnel is drilled from the lateral femoral cortex with a guide pin and reamer pointing 20 to 30° anteriorly and proximally while the arthroscope visualizes the femoral anterior cruciate ligament tunnel. The graft is routed under the fibular collateral ligament. The graft is fixed with a bioscrew while the knee is kept in 30° flexion and the tibia is kept in neutral rotation. We believe that lateral extra-articular tenodesis gives the anterior cruciate ligament graft a good chance for faster healing along with addressing anterolateral rotatory instability. Choosing a correct fixation point is very important to restore normal knee biomechanics.

A BIOMECHANICAL ASSESSMENT OF ZIMMER BIOMET'S NEXGEN TOTAL KNEE ARTHROPLASTY AS COMPARED WITH HEALTHY OLDER ADULTS

Total knee arthroplasty (TKA) aims to alleviate pain and restore joint biomechanics to an equivalent degree to age-matched peers.Zimmer Biomet's Nexgen TKA was the most common implant in the UK between 2003 and 2016. This study compared the biomechanical outcomes of the Nexgen implant against a cohort of healthy older adults to determine whether knee biomechanics is restored post-TKA.Patients with a primary Nexgen TKA and healthy adults >55 years old with no musculoskeletal deficits or diagnosis of arthritis were recruited locally.Eligible participants attended one research appointment. Bilateral knee range of motion (RoM) was assessed with a goniometer. A motorised arthrometer (GENOUROB) was then used to quantify the anterior-posterior laxity of each knee. Finally, gait patterns were analysed on a treadmill. An 8-camera Vicon motion capture system generated the biomechanical model.Preliminary statistical analyses were performed in SPSS (α = 0.05; required sample size for ongoing study: n=21 per group).The patient cohort (n=21) was older and had a greater BMI than the comparative group (n=13). Patients also had significantly poorer RoM than healthy older adults. However, there were no inter-group differences in knee laxity, walking speed or cadence. Gait kinematics were comparable in the sagittal plane during stance phase. Peak knee flexion during swing phase was lower in the patient group, however (49.0° vs 41.1°).Preliminary results suggest that knee laxity and some spatiotemporal and kinematic parameters of gait are restored in Nexgen TKA patients.While knee RoM remains significantly poorer in the patient cohort, an average RoM of >110° was achieved. This suggests the implant provides sufficient RoM for most activities of daily living. Further improvements to knee kinematics may necessitate additional rehabilitation.Future recruitment drives will concentrate on adults over the age of 70 for improved inter-group comparability.

BIOMECHANICAL INDICATORS OF SUCCESS AFTER TOTAL KNEE ARTHROPLASTY PREDICTED WITH PREOPERATIVE CLINICAL MEASUREMENTS

This study examined pre-operative measures to predict post-operative biomechanical outcomes in total knee arthroplasty (TKA) patients.Twenty-eight patients (female=12/male=16, age=63.6±6.9, BMI=29.9±7.4 kg/m2) with knee osteoarthritis scheduled to undergo TKA were included. All surgeries were performed by the same surgeon (GD) with a subvastus approach. Patients visited the gait lab within one-month prior to surgery and 12 months following surgery. At the gait lab, patients completed the knee injury and osteoarthritis outcome score (KOOS), a timed up and go (TUG), maximum knee flexion and extension strength evaluation, and a walking task. Variables of interest included the five KOOS sub-scores, TUG time, maximum knee flexion and extension strength normalized to body weight, walking speed, and peak knee biomechanics variables (flexion angle, abduction moment, power absorption). A Pearson's correlation was used to identify significantly correlated variables which were then inputted into a multiple regression.No assumption violations for the multiple regression existed for any variables. Pre-operative knee flexion and extension strength, TUG time, and age were used in the multiple regression. The multiple regression model statistically significantly predicted peak knee abduction moment, post-operative walking speed, and post-operative knee flexion strength. All four variables added statistically significantly to the prediction p<.05.Pre-operative KOOS values did not correlate with any biomechanical indicators of post-operative success. Age, pre-operative knee flexion and extension strength, and TUG times predicted peak knee abduction moment, which is associated with medial knee joint loading. These findings stress the importance of pre-surgery condition, as stronger individuals achieved better post-operative biomechanical outcomes. Additionally, younger patients had better outcomes, suggesting that surgeons should not delay surgery in younger patients. This delay in surgery may prevent patients from achieving optimal outcomes. Future studies should utilize a hierarchical multiple regression to identify which variables are most predictive.

Effect of Heading a Soccer Ball as an External Focus During a Drop Vertical Jump Task.

Research has demonstrated that performing a secondary task during a drop vertical jump (DVJ) may affect landing kinetics and kinematics. To examine the differences in the trunk and lower extremity biomechanics associated with anterior cruciate ligament (ACL) injury risk factors between a standard DVJ and a DVJ while heading a soccer ball (header DVJ). Descriptive laboratory study. Participants comprised 24 college-level soccer players (18 female and 6 male; mean ± SD age, 20.04 ± 1.12 years; height, 165.75 ± 7.25 cm; weight, 60.95 ± 8.47 kg). Each participant completed a standard DVJ and a header DVJ, and biomechanics were recorded using an electromagnetic tracking system and force plate. The difference (Δ) in 3-dimensional trunk, hip, knee, and ankle biomechanics between the tasks was analyzed. In addition, for each biomechanical variable, the correlation between the data from the 2 tasks was calculated. Compared to the standard DVJ, performing the header DVJ led to significantly reduced peak knee flexion angle (Δ = 5.35°; P = .002), knee flexion displacement (Δ = 3.89°; P = .015), hip flexion angle at initial contact (Δ = -2.84°; P = .001), peak trunk flexion angle (Δ = 13.11°; P = .006), and center of mass vertical displacement (Δ = -0.02m; P = .010), and increased peak anterior tibial shear force (Δ = -0.72 N/kg; P = .020), trunk lateral flexion angle at initial contact (Δ = 1.55°; P < .0001), peak trunk lateral flexion angle (Δ = 1.34°; P = .003), knee joint stiffness (Δ = 0.002 N*m/kg/deg; P = .017), and leg stiffness (Δ = 8.46 N/kg/m; P = .046) compared to those in standard DVJs. In addition, individuals' data for these variables were highly and positively correlated between conditions (r = 0.632-0.908; P < .001). The header DVJ task showed kinetic and kinematic parameters that suggested increased risk of ACL injury as compared with the standard DVJ task. Athletes may benefit from acquiring the ability to safely perform header DVJs to prevent ACL injury. To simulate real-time competition situations, coaches and athletic trainers should incorporate such dual tasks in ACL injury prevention programs.

Knee joint underloading does not evolve after a two-week reintroduction to running program after anterior cruciate ligament reconstruction

ObjectivesKnee underloading patterns have been reported mid- and long-term after return to running post-ACLR, but changes in these patterns during the reintroduction to running are unknown. We evaluated knee biomechanics in individuals within 6 months of ACL-R at the start and completion of a reintroduction to running program. DesignLongitudinal laboratory study. SettingThree-dimensional running biomechanics during instrumented treadmill running. Participants24 participants post-ACL-R with hamstring autograft and 24 healthy, matched controls. Main outcome measuresTibiofemoral joint (TFJ) and patellofemoral joint (PFJ) contact forces, peak knee extension moment and peak knee flexion angle. ResultsSignificant LIMB∗GROUP interactions (all p < 0.05) but no TIME effects were found. PFJ and TFJ contact forces, peak knee flexion angle and peak knee extensor moment were lower (all p < 0.001) on the injured-limb compared to both contralateral-limb and CONTROL. PFJ and TFJ contact forces and peak knee flexion, knee extension moment were greater (all p < 0.01) on the contralateral-limb of ACL-R compared to CONTROL. There was no change in knee biomechanics after two weeks of the reintroduction to running. ConclusionsClinicians should be aware that substantial and persistent knee underloading does not resolve upon reintroduction to running after ACL-R. Level of evidenceLongitudinal observational study, level III.

Overview of the different personalized total knee arthroplasty with robotic assistance, how choosing?

Current limitations in total knee arthroplasty (TKA) function and patient satisfaction stimulated us to question our practice. Our understanding of knee anatomy and biomechanics has evolved over recent years as we now consider that a more personalized joint reconstruction may be a better-targeted goal for TKA. Implant design and surgical techniques must be advanced to better reproduce the anatomy and kinematics of native knees and ultimately provide a forgotten joint. The availability of precision tools as robotic assistance surgery can help us recreate patient anatomy and ensure components are not implanted in a position that may compromise long-term outcomes. Robotic-assisted surgery is gaining in popularity and may be the future of orthopedic surgery. However, moving away from the concept of neutrally aligning every TKA dogma opens the door to new techniques emergence based on opinion and experience and leads to a certain amount of uncertainty among knee surgeons. Hence, it is important to clearly describe each technique and analyze their potential impacts and benefits. Personalized TKA techniques may be classified into 2 main families: unrestricted or restricted component orientation. In the restricted group, some will aim to reproduce native ligament laxity versus aiming for ligament isometry. When outside of their boundaries, all restricted techniques will induce anatomical changes. Similarly, most native knee having asymmetric ligaments laxity between compartments and within the same compartment during the arc of flexion; aiming for ligament isometry induces bony anatomy changes. In the current paper, we will summarize and discuss the impacts of the different robotic personalized alignment techniques, including kinematic alignment (KA), restricted kinematic alignment (rKA), inverse kinematic alignment (iKA), and functional alignment (FA). With every surgical technique, there are limitations and shortcomings. As our implants are still far from the native knee, it is primordial to understand the impacts and benefits of each technique. Mid to long data will help us in defining the new standards.

Combined Medial Patellofemoral Ligament, Medial Quadriceps Tendon-Femoral Ligament, and Medial Patellotibial Ligament Reconstruction for Patellar Instability: A Technical Note

Lateral patellar dislocations often occur in a young, athletic population of recurrent dislocators with generalized laxity and an interest in returning to an active lifestyle. A recent appreciation for the distal patellotibial complex has directed surgeons toward attempting to re-create the native anatomy and knee biomechanics during medial patellar reconstructive procedures. By reconstructing the medial patellotibial ligament (MPTL) in addition to the medial patella-femoral ligament (MPFL) and medial quadriceps tendon-femoral ligament (MQTFL), the current article describes a potentially more stable construct that can be utilized in patients with subluxation with the knee in full extension, patellar instability with the knee in deep flexion, genu recurvatum, and generalized hyperlaxity. Additionally, the current technique utilizes a tibialis anterior allograft. The purpose of this Technical Note is to describe, in detail, the current authors' technique for a combined MPFL, MQTFL, and MPTL reconstruction.

Effects of a Home-Based Foot–Ankle Exercise Program with Educational Booklet for Foot Dysfunctions in People with Diabetic Neuropathy: Results of the FOCA-II Randomized Controlled Clinical Trial

Exercise rehabilitation and education are important strategies for preventing the progression of diabetic neuropathy-related musculoskeletal deficits. The purpose of this randomized controlled trial was to investigate the effect of an 8-week home-based foot–ankle exercise program using an educational booklet on clinical outcomes (foot muscle strength and functionality; functional balance; diabetic neuropathy symptoms and severity; tactile and vibratory sensitivities; plantar pressure distribution; and foot–ankle, knee, and hip biomechanics during gait). Fifty participants with neuropathy were randomly allocated into an intervention group (59.1 ± 6.4 years, 23.5 ± 4.8 kg/m2, males = 6, females = 19) that performed the exercises for 8 weeks and a control group (56.5 ± 9.4 years, 22.9 ± 3.6 kg/m2, males = 5, females = 20) that received usual care recommendations. Generalized estimating equation method and intention-to-treat approaches were adopted. No significant differences were found for any clinical outcome after 8 weeks. Heel contact area increased in the intervention group compared to controls (p = 0.043, mean difference = 2.7 cm) and heel peak pressure was increased in controls compared to intervention (group effect p = 0.020, mean difference = -64.16 kPa) at 8 weeks. Controls showed increased joint moments for the hip at heel strike (p = 0.007) and for the knee and hip at push off over 8 and 16 weeks (p &lt; 0.001 and p = 0.009, respectively). Although the intervention is easy to perform and showed a good adherence (72%), home-based foot–ankle exercise programs are unlikely to sufficiently modify the main risk factors related to foot ulcers and to change foot–ankle kinematics and kinetics.

Biomechanical analysis of different levels of constraint in TKA during daily activities

BackgroundNumerous total knee prosthetic implants are currently available on the orthopedic market, and this variety covers a set of different levels of constraint: among the various models available, a significant role is covered by mobile bearing cruciate-retaining design with an ultra-congruent insert, mobile bearing cruciate-retaining design, fixed-bearing posterior stabilized prosthesis and fixed-bearing constrained condylar knee. A biomechanical comparative study among them could therefore be helpful for the clinical decision-making process. This study aimed to compare the effect of these different levels of constraint in the knee biomechanics of a patient, in three different configurations representing the typical boundary conditions experienced by the knee joint during daily activities.MethodThe investigation was performed via finite element analysis with a knee model based on an already published and validated one. Four different types of prosthesis designs were analyzed: two mobile-bearing models and two fixed-bearing models, each one having a different level of constraint. The different designs were incorporated in to the 3D finite element model of the lower leg and analyzed in three different configurations reproducing the landing and the taking-off phases occurring during the gait cycle and chair-rising. Implant kinetics (in terms of polyethylene contact areas and contact pressure), polyethylene and tibial bone stresses were calculated under three different loading conditions for each design.ResultsThe tibial stress distribution in the different regions of interest of the tibia remains relatively homogeneous regardless of the type of design used. The main relevant difference was observed between the mobile and fixed-bearing models, as the contact areas were significantly different between these models in the different loading conditions. As a consequence, significant changes in the stress distribution were observed at the interface between the prosthetic components, but no significant changes were noted on the tibial bone. Moreover, the different models exhibited a symmetrical medial and lateral distribution of the contact areas, which was not always common among all the currently available prostheses (i.e. medial pivot designs).ConclusionThe changes of the prosthetic implant did not induce a big variation of the stress distribution in the different regions of the tibial bone, while they significantly changed the distribution of stress at the interface between the prosthetic components.

Delivering Load-Modifying Gait Retraining Interventions via Telehealth in People With Medial Knee Osteoarthritis: A Pilot Randomized Placebo-Controlled Clinical Trial.

We aimed to investigate the effects of delivering 3 gait retraining interventions (toe-in, toe-out, and placebo gait) on proxy measures of medial knee load (early- and late-stance peak knee adduction moment [KAM], KAM impulse, and varus thrust) in people with knee osteoarthritis, using a hybrid model of face-to-face and telehealth-delivered sessions over 5 months. This was an originally planned 3-arm randomized placebo-controlled clinical trial. However, during the 2021 COVID-19 outbreak and lockdown in Sydney, Australia, the study became a pilot randomized controlled trial with the remainder of interventions delivered via telehealth. Nine individuals with symptomatic medial knee osteoarthritis were allocated to receive either a toe-in, toe-out, or posture re-education (placebo) gait retraining intervention. Primary outcomes of early- and late-stance peak KAM, KAM impulse, and varus thrust were assessed at baseline and follow-up. Eight participants returned for their follow-up gait assessment. Participants in both active intervention groups (toe-in and toe-out) achieved foot progression angle changes at follow-up. Overall, knee biomechanics in the placebo group did not change at follow-up. It is possible to achieve biomechanical changes in individuals with medial knee osteoarthritis when delivering gait retraining interventions via a hybrid model of face-to-face and telehealth.

High tibial osteotomy with ACL reconstruction

Knee malalignment in coronal and sagittal can alter knee biomechanics especially in anterior cruciate ligament (ACL) deficient knee that easily underdiagnosed and can endangered the reconstructed ACL to failure. Varus deformity is one of the coronal knee malalignment that shown increased tension on ACL and contribute to medial compartment degeneration. Sagittal malalignment also shown related effects on native ACL and reconstructed one. Increased posterior tibial slope will increase anterior tibia translation in weight-bearing and increase stress received by the reconstructed ACL. Eventually will leads to failure of the reconstructed ACL. High tibial osteotomy (HTO) can be utilized for deformity correction to create more biomechanically stable knee. ACL reconstruction can be performed simultaneously with HTO to achieve better outcomes and reduce re-tear rate of the reconstructed ACL.

The biomechanical effects of insoles with different cushioning on the knee joints of people with different body mass index grades.

Background: Enhancing knee protection for individuals who are overweight and obese is crucial. Cushioning insoles may improve knee biomechanics and play a significant protective role. However, the impact of insoles with varying cushioning properties on knee joints in individuals with different body mass index (BMI) categories remains unknown. Our aim was to investigate the biomechanical effects of insoles with different cushioning properties on knee joints across different BMI grades. Methods: Gravity-driven impact tests were used to characterize the cushioning properties of three types of Artificial Cartilage Foam (ACF18, 28, and 38) and ethylene-vinyl acetate (EVA) insoles. Knee joint sagittal, coronal, and vertical axis angles and moments were collected from healthy-weight (BMI 18.5-23.9kg/m2, n = 15), overweight (BMI 24.0-27.9kg/m2, n = 16), and obese (BMI ≥28.0kg/m2, n = 15) individuals randomly assigned four different insoles during a drop jump. The Kruskal-Wallis test and mixed model repeated measures analysis of variance were used to compare differences among cushioning and biomechanical data across various insoles, respectively. Results: ACF showed higher cushioning than EVA, and ACF38 was the highest among the three types of ACF (all p < 0.001). During the drop jump, the knee flexion angles and moments of the ACF insoles were lower than those of the EVA insoles, the knee adduction angles of the ACF18 and ACF28 insoles were lower than those of the EVA insoles, and ACF18 insoles increased the first cushion time (all p < 0.05) for all participants in whom biomechanical variables demonstrated no interactions between insoles and BMI. Regarding the BMI-dependent biomechanical variables, compared with the EVA insoles, ACF28 insoles decreased the knee flexion angle and ACF38 insoles decreased the knee adduction and rotation moment in the healthy-weight group; ACF18 insoles decreased the knee flexion angle and ACF38 insoles decreased the knee moment in the overweight group; ACF28 insoles decreased the knee flexion and adduction moment, and ACF38 insoles decreased the knee flexion angle and rotation moment in the obese group (all p < 0.05). Conclusion: Insoles with higher cushioning properties could improve knee biomechanics and provide better knee joint protection in people across different BMI ranges.

Passive stiffness of the quadriceps predicts the incidence of clinical knee osteoarthritis in twelve months.

Quadriceps weakness is a known risk factor for the onset of knee osteoarthritis (OA). In addition to muscle weakness, increased passive stiffness of the quadriceps may affect knee biomechanics and hence contribute to the pathogenesis of knee OA. However, the association between quadriceps stiffness and the risk of knee OA development has not been prospectively investigated. The aim of this study was to investigate how baseline quadriceps passive stiffness predicts the incidence of clinical knee OA at the 12-month follow-up. Prospective cohort study. University laboratory. Community-dwelling adults aged 60-80 years were recruited. We excluded participants with: 1) knee pain or known arthritis; 2) knee injury; 3) knee or hip joint replacement, 4) cognitive impairment; or 5) neurological conditions. At baseline, passive stiffness of the three superficial quadriceps muscle heads (rectus femoris [RF], vastus lateralis [VL], and vastus medialis oblique [VMO]) was evaluated using shear-wave ultrasound elastography. Knee muscle (quadriceps and hamstrings) strength was tested using a Cybex dynamometer. Knee OA was defined based on clinical criteria 12 months after baseline measurements. Generalized estimating equations were used to examine the associations of quadriceps stiffness and knee muscle strength with the risk of knee OA, controlling for age, sex, Body Mass Index, comorbidities, and activity level. The analyses included 158 knees (58.2% females, age: 65.6±4.1 years). Twenty-eight knees (17.7%) were classified as having clinical OA at 12 months. Compared with the lowest stiffness tertiles, the highest stiffness tertiles of the RF (relative risk =5.31, 95% CI: 1.34-21.0), VMO (4.15, 1.04-16.6), and total superficial quadriceps (6.35, 1.48-27.3) at baseline were significantly associated with a higher risk of knee OA at the follow-up. The highest strength tertile of quadriceps has a trend of association with a lower risk of knee OA than the lowest tertile (0.18, 0.03-1.25, P=0.083). Greater passive stiffness of the quadriceps at baseline was associated with a higher risk of clinical knee OA incidence at the 12-month follow-up. Interventions for reducing the passive stiffness of the quadriceps should be included in preventative training programs for older adults.

Comparison of proprioception, strength, and dynamic balance between aquatic and cycling trainings after arthroscopic partial meniscectomy during early rehabilitation in young male athletes

Arthroscopic partial meniscectomy (APM) strives to preserve knee biomechanics and function after the meniscal rupture. However, patients undergoing APM experience long-term impacts like proprioceptive deficit and functional decline. This study aimed to examine and compare the effects of aquatic and leg cycling trainings on young athletes undergone APM. Ninety-seven male athletes with APM were assigned to aquatic training group (ATG, n = 49) and cycling training group (CTG, n = 48). Both intervention trainings were conducted three times a week for 6 weeks after 2 weeks of APM. The rehabilitation training was the same in each session. The International Knee Documentation Committee (IKDC) questionnaire scores, knee joint position sense, Y-balance test, and isokinetic knee strength were measured before and after the interventions. Significant improvements were observed after the trainings regarding measured variables for both ATG and CTG groups. Comparison of the two groups found that ATG group had higher scores in IKDC and Y-balance test, greater muscle power, and lower absolute error in the joint position sense test compared to the CTG group. ATG and CTG are thus considered effective training interventions in early rehabilitation phase following the APM. Moreover, ATG may be more conducive than CTG in improving subjective knee symptoms, proprioception, and muscle power.

Relationship Between Knee Biomechanics and Pain in People With Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

Our primary aim was to determine the cross-sectional relationship between knee biomechanics during gait and pain in people with medial knee osteoarthritis. Our secondary aim was to evaluate differences in knee biomechanics between symptomatic and asymptomatic participants with medial knee osteoarthritis. Four online databases were searched from inception to July 2021. Eligible studies included people with medial/nonspecific knee osteoarthritis and a reported relationship between knee biomechanics during gait and pain or biomechanics of symptomatic and asymptomatic participants. Two reviewers independently extracted data and evaluated risk of bias. Random-effects meta-analyses were performed when three or more studies reported the same biomechanical variable for pooling (knee adduction moment [KAM], KAM impulse, varus thrust, and peak knee flexion moment [KFM]). Forty studies were included. Methodological quality ranged from 4 to 9/10. Forty-seven unique biomechanical variables were reported. For the KAM, there was no correlation with pain for peak values pooled (early stance and overall) (r=0.00, 95% confidence interval [95% CI]: -0.12, 0.11, k=16), a small negative correlation for early stance peak alone (r = -0.09, 95% CI -0.18, -0.002, k=12), and a medium positive correlation for the overall peak during stance (r=0.30, 95% CI 0.17, 0.42, k=4). Metaregression identified that body mass index moderated the peak KAM-pain relationship (P < 0.001). KAM impulse had a small positive correlation with pain (r=0.23, 95% CI 0.04, 0.40, k=5), and people with varus thrust had 3.84 greater odds of reporting pain compared with people without (95% CI 1.72, 8.53, k=3). Meta-analyses for the peak KFM and pain correlation and secondary aim were nonsignificant. Some knee gait biomechanics were associated with pain in this cohort. Longitudinal studies are required to determine causality.

Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running.

Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown. Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs. Cohort pilot study. Level 3. A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed. KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment (R2 = 0.35;P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb (R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment (R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb. These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR. Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

Do exist differences in kinematics and EMG of the hip and knee between male runners with and without patellofemoral pain in different running speeds?

ObjectivePatellofemoral pain (PFP) presents a higher prevalence in female runners, while PFP in male is somehow neglected. Moreover, the effects of progressive greater running speed have not been reported. This study investigates the influence of progressive greater running speed on lower limb tridimensional kinematics and muscle activation (EMG) in male runners with PFP while compared with controls. DesignCross-Sectional Design. MethodsThirteen runners with PFP and 18 controls ran in a treadmill under three different speeds: 9, 11, and 13 km/h. Principal component scores from kinematic data and EMG onset and amplitude were used to compare groups through the Mann-Whitney test at each running speed. ResultsMale PFP subjects presented increased hip internal rotation at 11 km/h and increased hip and knee internal at 13 km/h, as well as reduced knee adduction at all speeds. PFP subjects also ran with delayed and shorter vastus medialis oblique pre-activation compared with normal subjects. ConclusionsThis study demonstrated that PFP increased knee and hip internal rotation at higher demand running, therefore, it is important to evaluate the transverse plane of the hip and knee biomechanics in male runners with PFP to optimize the rehabilitation and reconditioning method of these subjects.

Robust automatic hexahedral cartilage meshing framework enables population-based computational studies of the knee.

Osteoarthritis of the knee is increasingly prevalent as our population ages, representing an increasing financial burden, and severely impacting quality of life. The invasiveness of in vivo procedures and the high cost of cadaveric studies has left computational tools uniquely suited to study knee biomechanics. Developments in deep learning have great potential for efficiently generating large-scale datasets to enable researchers to perform population-sized investigations, but the time and effort associated with producing robust hexahedral meshes has been a limiting factor in expanding finite element studies to encompass a population. Here we developed a fully automated pipeline capable of taking magnetic resonance knee images and producing a working finite element simulation. We trained an encoder-decoder convolutional neural network to perform semantic image segmentation on the Imorphics dataset provided through the Osteoarthritis Initiative. The Imorphics dataset contained 176 image sequences with varying levels of cartilage degradation. Starting from an open-source swept-extrusion meshing algorithm, we further developed this algorithm until it could produce high quality meshes for every sequence and we applied a template-mapping procedure to automatically place soft-tissue attachment points. The meshing algorithm produced simulation-ready meshes for all 176 sequences, regardless of the use of provided (manually reconstructed) or predicted (automatically generated) segmentation labels. The average time to mesh all bones and cartilage tissues was less than 2min per knee on an AMD Ryzen 5600X processor, using a parallel pool of three workers for bone meshing, followed by a pool of four workers meshing the four cartilage tissues. Of the 176 sequences with provided segmentation labels, 86% of the resulting meshes completed a simulated flexion-extension activity. We used a reserved testing dataset of 28 sequences unseen during network training to produce simulations derived from predicted labels. We compared tibiofemoral contact mechanics between manual and automated reconstructions for the 24 pairs of successful finite element simulations from this set, resulting in mean root-mean-squared differences under 20% of their respective min-max norms. In combination with further advancements in deep learning, this framework represents a feasible pipeline to produce population sized finite element studies of the natural knee from subject-specific models.

A decellularized and sterilized human meniscus allograft for off-the-shelf meniscus replacement

PurposeMeniscus tears are one of the most frequent orthopedic knee injuries, which are currently often treated performing meniscectomy. Clinical concerns comprise progressive degeneration of the meniscus tissue, a change in knee biomechanics, and an early onset of osteoarthritis. To overcome these problems, meniscal transplant surgery can be performed. However, adequate meniscal replacements remain to be a great challenge. In this research, we propose the use of a decellularized and sterilized human meniscus allograft as meniscal replacement.MethodsHuman menisci were subjected to a decellularization protocol combined with sterilization using supercritical carbon dioxide (scCO2). The decellularization efficiency of human meniscus tissue was evaluated via DNA quantification and Hematoxylin & Eosin (H&E) and DAPI staining. The mechanical properties of native, decellularized, and decellularized + sterilized meniscus tissue were evaluated, and its composition was determined via collagen and glycosaminoglycan (GAG) quantification, and a collagen and GAG stain. Additionally, cytocompatibility was determined in vitro.ResultsHuman menisci were decellularized to DNA levels of ~ 20 ng/mg of tissue dry weight. The mechanical properties and composition of human meniscus were not significantly affected by decellularization and sterilization. Histologically, the decellularized and sterilized meniscus tissue had maintained its collagen and glycosaminoglycan structure and distribution. Besides, the processed tissues were not cytotoxic to seeded human dermal fibroblasts in vitro.ConclusionsHuman meniscus tissue was successfully decellularized, while maintaining biomechanical, structural, and compositional properties, without signs of in vitro cytotoxicity. The ease at which human meniscus tissue can be efficiently decellularized, while maintaining its native properties, paves the way towards clinical use.