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Context: The Y-Balance Test Lower Quarter (YBT-LQ) is a widely utilized tool for evaluating dynamic postural control, requiring a combination of mobility and strength. This study aimed to investigate the combined relationship between isometric thigh muscle strength and joint kinematics on YBT-LQ performance. Design: Cross-sectional laboratory study. Methods: Isometric quadriceps and hamstrings strength were measured before the YBT-LQ in 39 healthy participants (27 females and 12 males). The test was performed under 3-dimensional markerless motion capture, where joint kinematics were extracted from the maximum reach position from each direction. Three multivariable linear regression models were then used to determine the strongest combination of predictors for YBT-LQ performance. Results: Greater hamstrings strength and increased knee flexion, ankle dorsiflexion, and trunk ipsilateral-flexion joint angles explained 56.8% (P <.001) of the variance in anterior reach. Hip flexion, knee flexion, and ankle dorsiflexion angles were the strongest predictors for posteromedial reach distance, explaining 73.0% of the variance (P <.001). Last, 43.3% (P <.001) of the variance in posterolateral reach distance was predicted by hamstring strength and knee-flexion angle. Conclusions: These results emphasize the importance of hamstring strength in YBT-LQ performance across different reach directions. Additionally, the kinematics illustrate a potential movement strategy for maximizing reach distance on the YBT-LQ in healthy individuals. Clinicians can utilize this information to guide interventions aimed at improving dynamic postural control, particularly by focusing on increasing hamstring strength and testing for impairments in specific movement patterns. [ABSTRACT FROM AUTHOR]

The mechanical efficiency of human locomotion has been studied extensively. The mechanical efficiency of the whole body occasionally exceeds muscle efficiency during bouncing type gaits. It is thought to occur due to elasticity and stiffness of the tendinomuscular system and neuromuscular functions, especially stretch reflexes. In addition, the lower limb joint kinetics affect mechanical efficiency. We investigated the impact of varying external work on mechanical efficiency and lower limb kinetics during repeated sledge jumping. Fifteen male runners performed sledge jumping for 4 minutes at 3 different sledge inclinations. Lower limb kinematics, ground reaction forces, and expired gases were analyzed. Mechanical efficiency did not differ according to sledge inclination. Mechanical efficiency correlated positively with the positive mechanical work of the knee and hip joints and the negative contribution of the hip joints. Conversely, it correlated negatively with both the positive and negative contributions of the ankle joint. This may be attributable to the greater workload in this study versus previous studies. To achieve greater external work, producing more mechanical energy at the proximal joint and transferring it to the distal joint could be an effective strategy for improving mechanical efficiency because of the greater force-generating capability of distal joint muscles. [ABSTRACT FROM AUTHOR]

Purpose: To compare the kinematic profile of 2 underwater pullout breaststroke techniques. Methods: Sixteen swimmers (9 men, 20.67 [2.71] y old; 7 women, 18.86 [0.83] y old) performed 3 × 25-m breaststroke using 2 pullout breaststroke techniques: Fly-Kick first and Combined. A speedometer was used to assess the peak and the mean velocity during the glide, propulsion, and recovery phases of both techniques, as well as for the total underwater sequence. The underwater distance was retrieved from video footage and was considered for each pullout technique. The range of motion of the knee during the fly-kick was also retrieved, and the time to complete the 25 m was considered the performance outcome, accompanied by the mean velocity, stroke rate, stroke length, and stroke index. Results: Velocity–time series showed different profiles between pullout techniques (P ≤.05) mostly in the glide and propulsion phases for males and females, respectively. The mean velocity of 25 m was shown to be greater in females when using the Fly-Kick first technique (P =.05, d = 0.36). Greater values in total underwater distance and knee range of motion were also observed for this technique in both cohorts. Conclusions: Female swimmers presented a higher performance when using the Fly-Kick first technique. Different kinematic profiles arise when swimmers use different underwater pullout techniques where the Fly-Kick first may allow them to reach higher kinematical standard. [ABSTRACT FROM AUTHOR]

Following anterior cruciate ligament reconstruction (ACLR), patients exhibit abnormal walking mechanics and quadriceps dysfunction. Quadriceps dysfunction has been largely attributed to muscle atrophy and weakness. While important, these factors do not capture intrinsic properties of muscle that govern its ability to generate force and withstand load. While fascicle abnormalities after ACLR have been documented in early stages of recovery (<12 mo), long-term effects of ACLR on fascicle mechanics remain unexplored. We evaluated quadriceps fascicle mechanics during walking 3 years post-ACLR and examined the relationship with knee mechanics. Participants included 24 individuals with ACLR and 24 Controls. Linear mixed models compared the ACLR, Contralateral, and Controls limbs for (1) quadriceps strength, (2) fascicle architecture and mechanics, and (3) knee mechanics. No difference in strength or overall fascicle length excursions was found between limbs. The ACLR limb exhibited longer fascicles at heel strike and peak knee extension moment (P <.001–.004), and smaller fascicle angles at heel strike, peak knee extension moment, and overall suppressed fascicle angle excursions (P <.001–.049) relative to the Contralateral and/or Control limb. This indicates an abnormality in fascicle architecture and mechanics following ACLR and suggests abnormalities in contractile function that cannot be explained by muscle weakness and may contribute to long-term gait irregularities. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of knee joint range of motion (RoM) on the torque–velocity relationship and fatigue in the knee extensor muscles of 7 young (median = 26 y) and 7 older (68 y) adults. Each leg was assigned a RoM (35° or 75°) over which to perform a torque–velocity protocol (maximal isokinetic contractions, 60–300°·s−1) and a fatigue protocol (120 maximal contractions at 120°·s−1, 0.5 Hz). Six older participants were unable to reach 300°·s−1 over 35°. Therefore, the velocity eliciting 75% of peak torque at 60°·s−1 (V75, °·s−1) was calculated for each RoM from a fit of individual torque–velocity curves (60–240°·s−1), and ΔV75 (35°–75°) was determined. Fatigue (final torque/initial torque) was used to calculate Δfatigue (35°–75°). ΔV75 was not different from 0 in young (−28.3°·s−1 [−158.6 to 55.7], median [range], P =.091) or older (−18.5°·s−1 [−95.0 to 23.9], P =.128), with no difference by age (P =.710). In contrast, fatigue was greater for 75° in young (Δfatigue = 25.9% [17.5–30.3], P =.018) and older (17.2% [11.9–52.9], P =.018), with no effect of age (P =.710). These data indicate that, regardless of age, RoM did not alter the torque–velocity relationship between 60 and 240°·s−1, and fatigue was greater with a larger RoM. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the effect of attentional focus instructions on the biomechanical variables associated with the risk of anterior cruciate ligament injury of the knee joint during a drop landing task using a time series analysis. Ten female volleyball players (age: 20.4 ± 0.8 years, height: 169.7 ± 7.1 cm, mass: 57.6 ± 3.1 kg, experience: 6.3 ± 0.8 years) performed landings from a 50 cm height under three different attentional focus conditions: (1) external focus (focus on landing as soft as possible), (2) internal focus (focus on bending your knees when you land), and (3) control (no-focus instruction). Statistical parameter mapping in the sagittal plane during the crucial first 30% of landing time showed a significant effect of attentional focus instructions. Despite the similarity in landing performance across foci instructions, adopting an external focus instruction promoted reduced vertical ground reaction force and lower sagittal flexion moment during the first 30% of execution time compared to internal focus, suggesting reduced knee loading. Therefore, adopting an external focus of attention was suggested to reduce most biomechanical risk variables in the sagittal plane associated with anterior cruciate ligament injuries, compared to internal focus and control condition. No significant differences were found in the frontal and horizontal planes between the conditions during this crucial interval. [ABSTRACT FROM AUTHOR]

Bilateral gait symmetry is an essential requirement for normal walking since asymmetric gait patterns increase the risk of falls and injuries. While human gait control heavily relies on the contribution of sensory inputs, the role of sensory systems in producing symmetric gait has remained unclear. This study evaluated the influence of vision as a dominant sensory system on symmetric gait production. Ten healthy adults performed treadmill walking with and without vision. Twenty-two gait parameters including ground reaction forces, joint range of motion, and other spatial–temporal gait variables were evaluated to quantify gait symmetry and compared between both visual conditions. Visual block caused increased asymmetry in most parameters of ground reaction force, however mainly in the vertical direction. When vision was blocked, symmetry of the ankle and knee joint range of motion decreased, but this change did not occur in the hip joint. Stance and swing time symmetry decreased during no-vision walking while no significant difference was found for step length symmetry between the two conditions. This study provides a comprehensive analysis to reveal how the visual system influences bilateral gait symmetry and highlights the important role of vision in gait control. This approach could be applied to investigate how vision alters gait symmetry in patients with disorders to help better understand the role of vision in pathological gaits. [ABSTRACT FROM AUTHOR]

Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés) before and after typical dance-specific choreography. Lower-extremity kinetic data were collected from 14 healthy female dancers during a series of sautés performed before and after 3 minutes of dance. Percent contributions of the lower-extremity joints to the whole-limb mechanical energy expenditure during ground contact were calculated. The jumps performed at the beginning were compared with the jumps at the end of the dance choreography. Dancers maintained the jump rate and consistent whole-limb mechanical energy expenditure between the jump series. As expected, for both jump series, the sautés had greater relative energetic contribution from the ankle and knee as compared with lesser contribution from the hip and toe. However, we observed lesser contribution from the knee and greater contribution from the hip after a 3-minute dance. After performing typical dance choreography, the dancers demonstrated a distal to proximal redistribution of individual joints' contribution to whole-limb mechanical energy expenditure. [ABSTRACT FROM AUTHOR]

We proposed an end-to-end deep learning convolutional neural network (DCNN) for region-of-interest based multi-parameter quantification (RMQ-Net) to accelerate quantitative ultrashort echo time (UTE) MRI of the knee joint with automatic multi-tissue segmentation and relaxometry mapping. The study involved UTE-based T1 (UTE-T1) and Adiabatic T1ρ (UTE-AdiabT1ρ) mapping of the knee joint of 65 human subjects, including 20 normal controls, 29 with doubtful-minimal osteoarthritis (OA), and 16 with moderate-severe OA. Comparison studies were performed on UTE-T1 and UTE-AdiabT1ρ measurements using 100%, 43%, 26%, and 18% UTE MRI data as the inputs and the effects on the prediction quality of the RMQ-Net. The RMQ-net was modified and retrained accordingly with different combinations of inputs. Both ROI-based and voxel-based Pearson correlation analyses were performed. High Pearson correlation coefficients were achieved between the RMQ-Net predicted UTE-T1 and UTE-AdiabT1ρ results and the ground truth for segmented cartilage with acceleration factors ranging from 2.3 to 5.7. With an acceleration factor of 5.7, the Pearson r-value achieved 0.908 (ROI-based) and 0.945 (voxel-based) for UTE-T1, and 0.733 (ROI-based) and 0.895 (voxel-based) for UTE-AdiabT1ρ, correspondingly. The results demonstrated that RMQ-net can significantly accelerate quantitative UTE imaging with automated segmentation of articular cartilage in the knee joint.

Context: The hamstrings are the most commonly injured muscle in sports and are especially injury prone in lengthened positions. Measuring knee muscle strength in such positions could be relevant to establish injury risk. Handheld dynamometry has been shown to be a valid, reliable, and practical tool to measure isometric muscle strength clinically. The aim of this study was to assess the validity and reliability of the assessment of isometric knee muscle strength with a handheld dynamometer (HHD) at various muscle lengths, by modifying the hip and knee angles during testing. Design: Concurrent validity and test--retest reliability. Methods: Thirty young healthy participants were recruited. Hamstring and quadriceps isometric strength was measured with a HHD and with an isokinetic dynamometer, over 2 testing sessions, in a randomized order. Isometric strength was measured on the right lower limb in 6 different positions, with the hip at either 0° or 80° of flexion and the knee at either 30°, 60°, or 90° of flexion. Pearson and Spearman correlations were used to assess the validity, and intraclass correlation coefficients were calculated to establish the test--retest reliability of the HHD. Results: Good to excellent reliability and moderate to high validity were found in all the tested muscle length positions, except for the hamstrings in a seated position with the knee extended at 30°. Conclusions: The use of a HHD is supported in the clinical setting to measure knee muscle strength at varying muscle lengths in healthy adults, but not for the hamstrings in a lengthened position (hip flexed and knee extended). These results will have to be confirmed in sport-specific populations. [ABSTRACT FROM AUTHOR]

Context: A reduced knee extensor moment (KEM) in the involved limb and asymmetry in the KEM during landing tasks are observed after anterior cruciate ligament reconstruction (ACLR). There is limited information about the association of kinetic and kinematic parameters with the KEM during landing after ACLR. This study investigated the association of the anterior--posterior center of pressure (AP-COP) position, vertical ground reaction force (VGRF), and lower limb joint angles with the KEM during landing in female athletes following ACLR. Design: Cross-sectional study. Methods: Twenty-two female athletes who underwent ACLR performed a drop vertical jump at 7.9 (1.7) months after surgery. We evaluated the KEM, AP-COP position, VGRF, and sagittal plane hip, knee, and ankle angles using a 3-dimensional motion analysis system with force plates. Results: The peak KEM in the involved limb was significantly smaller than that in the uninvolved limb during landing (1.43 [0.33] N·m/kg/m vs 1.84 [0.41] Nm/kg/m, P = .001). The VGRF in the involved limb was significantly smaller than that in the uninvolved limb (11.9 [2.3] N/kg vs 14.6 [3.5] N/kg, P = .005). The limb symmetry index of the KEM was predicted by that of the VGRF (P < .001, R² = .621, β = 0.800). The KEM was predicted by the AP-COP position in the involved limb (P = .015, R² = .227, β = 0.513) and by the VGRF in the uninvolved limb (P = .018, R² = .213, β = 0.500). No significant correlation was noted between the KEM and the lower limb joint angles. Conclusions: The AP-COP position and VGRF were associated with the KEM during landing. Evaluating the VGRF and AP-COP position, not the lower limb joint angles, may contribute to understanding the KEM during double-leg landing after ACLR in the clinical setting. [ABSTRACT FROM AUTHOR]

Context: Anterior cruciate ligament injuries are directly related to the control of dynamic knee valgus in the landing of a jump, and this is mainly due to the correct activation and neuromuscular function of the lower-extremity muscles. The aim of the study is to assess the relationship between lower limb muscle activity during a single-legged drop jump and knee frontal plane projection angle (FPPA). Design: A correlation study. Methods: Thirty healthy collegiate female athletes were included in the study. Main outcomes measures were peak knee FPPA and muscle activity (% of maximal voluntary isometric contraction). Peak knee FPPA during a single-legged drop jump test was identified using a 2-dimensional motion analysis system. Muscle activity was assessed using a surface electromyograph for gluteus maximus, gluteus medius, biceps femoris, semitendinosus, vastus medialis quadriceps, vastus lateralis quadriceps, medial gastrocnemius, and lateral gastrocnemius. All variables were assessed for both dominant and nondominant limbs. A correlation analysis between peak knee FPPA and muscle activity was performed. Statistical significance was set at P <.05. Results: A mean peak knee FPPA of 14.52° and 13.38° was identified for dominant and nondominant limb single-legged drop jump test, respectively. Muscle activity (% of maximal voluntary isometric contraction) for muscles assessed ranged from 43.97% to 195.71% during the single-legged drop jump test. The correlation analysis found no significant correlation between any of the muscles assessed and peak knee FPPA during the single-legged drop jump test (Pearson coefficient between −.3 and.1). Conclusions: There is no association between muscle activity from the lower limb muscles and the knee FPPA during a single-legged drop jump in female athletes. Thus, different muscle properties should be assessed in order to understand such an important movement as the knee FPPA during a jump. [ABSTRACT FROM AUTHOR]

BACKGROUND: The polyarticular nature of Osteoarthritis (OA) tends to manifest in multi-joints. Associations between cartilage health in connected joints can help identify early degeneration and offer the potential for biomechanical intervention. Such associations between hip and knee cartilages remain understudied. PURPOSE: To investigate T1p associations between hip-femoral and acetabular-cartilage subregions with Intra-limb and Inter-limb patellar cartilage; whole and deep-medial (DM), deep-lateral (DL), superficial-medial (SM), superficial-lateral (SL) subregions. STUDY TYPE: Prospective. SUBJECTS: Twenty-eight subjects (age 55.1 ± 12.8 years, 15 females) with none-to-moderate hip-OA while no radiographic knee-OA. FIELD STRENGTH/SEQUENCE: 3-T, bilateral hip, and knee: 3D-proton-density-fat-saturated (PDFS) Cube and Magnetization-Prepared-Angle-Modulated-Partitioned-k-Space-Spoiled-Gradient-Echo-Snapshots (MAPSS). ASSESSMENT: Ages of subjects were categorized into Group-1 (≤40), Group-2 (41-50), Group-3 (51-60), Group-4 (61-70), Group-5 (71-80), and Group-6 (≥81). Hip T1p maps, co-registered to Cube, underwent an atlas-based algorithm to quantify femoral and acetabular subregional (R2-R7) cartilage T1p. For knee Cube, a combination of V-Net architectures was used to segment the patellar cartilage and subregions (DM, DL, SM, SL). T1p values were computed from co-registered MAPSS. STATISTICAL TESTS: For Intra-and-Inter-limb, 5 optimum predictors out of 13 (Hip subregional T1p, age group, gender) were selected by univariate linear-regression, to predict outcome (patellar T1p). The top five predictors were stepwise added to six linear mixed-effect (LME) models. In all LME models, we assume the data come from the same subject sharing the same random effect. The best-performing models (LME-modelbest) selected via ANOVA, were tested with DM, SM, SL, and DL subregional-mean T1p. LME assumptions were verified (normality of residuals, random-effects, and posterior-predictive-checks). RESULTS: LME-modelbest (Intra-limb) had significant negative and positive fixed-effects of femoral-R5 and acetabular-R2 T1p, respectively (conditional-R2 = 0.581). LME-modelbest (Inter-limb) had significant positive fixed-effects of femoral-R3 T1p (conditional-R2 = 0.26). DATA CONCLUSION: Significant positive and negative T1p associations were identified between load-bearing hip cartilage-subregions vs. ipsilateral and contralateral patellar cartilages respectively. The effects were localized on medial subregions of Inter-limb, in particular. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 1.

OBJECTIVE: Realignment osteotomy performed concomitantly with cartilage restoration typically requires early restricted weightbearing and can add significant morbidity, potentially leading to an increased risk of early perioperative complications. The purpose of this study was to compare the 30-day complication rates after isolated cartilage restoration (ICR) versus concomitant cartilage restoration and osteotomy (CRO) using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. DESIGN: NSQIP registries between 2006 and 2019 were queried using Current Procedural Terminology codes to identify patients undergoing ICR (autologous chondrocyte implantation, osteochondral autograft transfer, or osteochondral allograft transplantation) and CRO (with concomitant high tibial osteotomy, distal femoral osteotomy, and/or tibial tubercle osteotomy). Complications rates between treatment groups were compared using multivariate logistic regression analyses adjusted for sex, age, steroid use, and respiratory status. RESULTS: A total of 773 ICR and 97 CRO surgical procedures were identified. Mean patient ages were 35.9 years for the ICR group and 31.2 years for the CRO group. Operative time was significantly longer in the CRO group (170.8 min) compared with the ICR group (97.8 min). Multivariate analysis demonstrated no significant differences in rates of PE, VTE, and all-cause readmission between the ICR and CRO groups. No events of wound disruption, SSI and reoperation were found in the CRO group, while the ICR group was characterized by low rates of wound disruption, reoperation, and SSI (

Purpose: This preregistered trial investigated how 6 weeks of unilateral flywheel leg-curl and hip-extension training impact isokinetic, isometric, and flywheel strength and power outcomes. Methods: The study involved 11 male university athletes (age 22 [2] y; body mass 77.2 [11.3] kg; height 1.74 [0.09] m) with one leg randomly allocated to flywheel training and one leg to control. Unilateral eccentric and isometric knee-flexion torque and flywheel unilateral leg-curl and hip-extension peak power were tested. Training intensity and volume (3–4 sets of 6 + 2 repetitions) were progressively increased. Results: The intervention enhanced hip-extension concentric (P <.01, d = 1.76, large) and eccentric (P <.01, d = 1.33, large) peak power more than the control (significant interaction effect). Similarly, eccentric (P =.023, d = 1.05, moderate) peak power was enhanced for the leg curl. No statistically significant differences between conditions were found for isokinetic eccentric (P =.086, d = 0.77, moderate) and isometric (P =.431, d = 0.36, small) knee-flexor strength or leg-curl concentric peak power (P =.339, d = 0.52, small). Statistical parametric mapping analysis of torque–angle curves also revealed no significant (P >.05) time–limb interaction effect at any joint angle. Conclusion: Unilateral flywheel hamstring training improved knee-flexor eccentric peak power during unilateral flywheel exercise but not flywheel concentric, isokinetic eccentric, or isometric (long-lever) knee-flexor strength. [ABSTRACT FROM AUTHOR]

Chronic exposure to high tibiofemoral joint (TFJ) contact forces can be detrimental to knee joint health. Load carriage increases TFJ contact forces, but it is unclear whether medial and lateral tibiofemoral compartments respond similarly to incremental load carriage. The purpose of our study was to compare TFJ contact forces when walking with 15% and 30% added body weight. Young healthy adults (n = 24) walked for 5 minutes with no load, 15% load, and 30% load on an instrumented treadmill. Total, medial, and lateral TFJ contact peak forces and impulses were calculated via an inverse dynamics informed musculoskeletal model. Results of 1-way repeated measures analyses of variance (α =.05) demonstrated total, medial, and lateral TFJ first peak contact forces and impulses increased significantly with increasing load. Orthogonal polynomial trends demonstrated that the 30% loading condition led to a curvilinear increase in total and lateral TFJ impulses, whereas medial first peak TFJ contact forces and impulses responded linearly to increasing load. The total and lateral compartment impulse increased disproportionally with load carriage, while the medial did not. The medial and lateral compartments responded differently to increasing load during walking, warranting further investigation because it may relate to risk of osteoarthritis. [ABSTRACT FROM AUTHOR]

Foot stance and club type's relationship with lead knee joint biomechanics and possible involvement with injury incidences in amateur golfers have not been evaluated. This study included 16 male right-handed amateur golfers who performed golf swings with 2 different foot stances (straight and open) using 4 different club types (driver, 3 iron, 6 iron, and 9 iron) while standing on 2 force plates in a motion capture laboratory. A custom program calculated the kinematics and kinetics of the lead knee. Overall, the open stance reduced most translations, rotations, forces, and torques of the lead knee in all 4 club types when compared with the straight stance. The open stance reduced the rotation motion (−28%), compressive force (−5%), and rotation torque (−9%) when compared with the straight stance, which are the highest contributors to grinding of cartilage. The driver club had significantly larger values in most translations, rotations, forces, and torques when compared among the 4 club types. The open stance reduced the rotation motion, compressive force, and rotation torque in the lead knee joint compared with the straight stance. Lead knee joint biomechanics should be monitored to reduce injury in amateur golfers. [ABSTRACT FROM AUTHOR]

It is not currently possible to directly and noninvasively measure in vivo patellofemoral joint contact force during dynamic movement; therefore, indirect methods are required. Simple models may be inaccurate because patellofemoral contact forces vary for the same knee flexion angle, and the patellofemoral joint has substantial out-of-plane motion. More sophisticated models use 3-dimensional kinematics and kinetics coupled to a subject-specific anatomical model to predict contact forces; however, these models are time consuming and expensive. We applied a principal component analysis prediction and regression method to predict patellofemoral joint contact forces derived from a robust musculoskeletal model using exclusively optical motion capture kinematics (external approach), and with both patellofemoral and optical motion capture kinematics (internal approach). We tested this on a heterogeneous population of asymptomatic subjects (n = 8) during ground-level walking (n = 12). We developed equations that successfully capture subject-specific gait characteristics with the internal approach outperforming the external. These approaches were compared with a knee-flexion based model in literature (Brechter model). Both outperformed the Brechter model in interquartile range, limits of agreement, and the coefficient of determination. The equations generated by these approaches are less computationally demanding than a musculoskeletal model and may act as an effective tool in future rapid gait analysis and biofeedback applications. [ABSTRACT FROM AUTHOR]

Previous research has shown that there are differences in mechanical energy, kinematics, and muscle activation when comparing walking on level and incline surfaces, especially on inclines above 15%. Muscle activations are significantly different while walking on extreme inclines, suggesting a different coordination pattern. We utilized continuous relative phase to assess walking kinematic coordination with respect to increased incline angles. Twelve healthy, college-aged individuals walked for 7 inclines of 1 minute each on a motorized treadmill at 3 mph at 0%, 5%, 10%, 15%, 20%, 25%, and 30% inclines. Kinematic data were collected during the last 20 seconds of each stage (120 Hz). Segmental and joint angles and angular velocities in the sagittal plane were calculated, from which continuous relative phase was determined for 3 joint couples: hip–knee, hip–ankle, and knee–ankle. There were significant differences in the coordination patterns during the first part of the contact phase in the hip–knee and hip–ankle couplings between the 0% and 30% inclines, with all 3 joint couplings becoming more in-phase at inclines above 15%. Importantly, the hip–knee coupling changed significantly from more out-of-phase to more in-phase between 10% and 15% incline. Shifting lower-extremity joint coordination in response to extreme inclines identifies potential coordinative strategies to achieve steep walking. [ABSTRACT FROM AUTHOR]

PurposeTo develop a 3D phase modulated UTE adiabatic T1ρ (PM-UTE-AdiabT1ρ ) sequence for whole knee joint mapping on a clinical 3 T scanner.MethodsThis new sequence includes six major features: (1) a magnetization reset module, (2) a train of adiabatic full passage pulses for spin locking, (3) a phase modulation scheme (i.e., RF cycling pair), (4) a fat saturation module, (5) a variable flip angle scheme, and (6) a 3D UTE Cones sequence for data acquisition. A simple exponential fitting was used for T1ρ quantification. Phantom studies were performed to investigate PM-UTE-AdiabT1ρ 's sensitivity to compositional changes and reproducibility as well as its correlation with continuous wave-T1ρ measurement. The PM-UTE-AdiabT1ρ technique was then applied to five ex vivo and five in vivo normal knees to measure T1ρ values of femoral cartilage, meniscus, posterior cruciate ligament, anterior cruciate ligament, patellar tendon, and muscle.ResultsThe phantom study demonstrated PM-UTE-AdiabT1ρ 's high sensitivity to compositional changes, its high reproducibility, and its strong linear correlation with continuous wave-T1ρ measurement. The ex vivo and in vivo knee studies demonstrated average T1ρ values of 105.6 ± 8.4 and 77.9 ± 3.9 ms for the femoral cartilage, 39.2 ± 5.1 and 30.1 ± 2.2 ms for the meniscus, 51.6 ± 5.3 and 29.2 ± 2.4 ms for the posterior cruciate ligament, 79.0 ± 9.3 and 52.0 ± 3.1 ms for the anterior cruciate ligament, 19.8 ± 4.5 and 17.0 ± 1.8 ms for the patellar tendon, and 91.1 ± 8.8 and 57.6 ± 2.8 ms for the muscle, respectively.ConclusionThe 3D PM-UTE-AdiabT1ρ sequence allows volumetric T1ρ assessment for both short and long T2 tissues in the knee joint on a clinical 3 T scanner.

Purpose: To compare the effects of graded hypoxia during exhaustive intermittent cycling on subsequent rapid and maximal torque-production capacity. Methods: Fifteen well-trained cyclists repeated intermittent cycling bouts (15 s at 30% of anaerobic power reserve; rest = 45 s) until exhaustion at sea level (FiO2 ∼0.21/end-exercise arterial oxygen saturation ∼96%), moderate hypoxia (FiO2 ∼0.16/∼90%), and severe hypoxia (FiO2 ∼0.12/∼79%). Rapid (rate of torque development [RTD]) and maximal isometric torque-production capacities of the knee extensors were assessed at baseline (visit 1) and exhaustion (visits 2–4). Results: Exercise capacity decreased with hypoxia severity (39 [30], 22 [13], and 13 [6] cycle efforts in sea level, moderate hypoxia, and severe hypoxia, respectively; P =.002). Changes in maximal-voluntary-contraction torque between baseline and postexercise in all conditions were not statistically significant (pooled values: −2.6% [5.7%]; P =.162). Peak RTD measured postexercise was reduced below baseline in all conditions (–21.5% [5.1%]; P ≤.015). Compared with baseline, absolute RTD values were lower at 0- to 30-millisecond (–35.1% [5.3%], P ≤.020), 0- to 50-millisecond (–40.0% [3.9%], P ≤.002), 0- to 100-millisecond (–30.7% [3.7%], P ≤.001), and 0- to 200-millisecond (–18.1% [2.4%], P ≤.004) time intervals in all conditions. Conclusions: Exhaustive intermittent cycling induces substantial yet comparable impairments in RTD of knee extensors between normoxia and moderate to severe hypoxia. [ABSTRACT FROM AUTHOR]

Purpose: After anterior cruciate ligament reconstruction (ACL-R), knee muscle strength symmetry is used as part of the return-to-sport criteria. However, little is known about the changes in the force–velocity (F–V) relationship, which could affect athletic performance. This study investigated the F–V relationship of knee muscles at 4 and 8 months after ACL-R, using the 2-point method tested by isokinetic dynamometry. Methods: A total of 103 physically trained individuals (24.6 [9.3] y, 59.2% male) who underwent primary ACL-R were included. Demographic information and surgery characteristics were collected at 6 weeks postoperatively. Isokinetic knee flexors' and extensors' peak torques were measured at 60° and 240° per second in the concentric mode at 4 and 8 months postoperative. Peak torques and angular velocities were converted to force and linear velocity for calculating maximum isometric force (F0) and the slope of the regression line (F–V slope). Results: At 4 and 8 months postoperative, F0 was significantly lower and F–V slope was significantly less steep (less negative) on the operated leg compared with the nonoperated leg for knee extensors (P <.001) and flexors (P <.001–.002). The limb symmetry index calculated using F0 was lower than the limb symmetry indexes assessed at 60° and 240° per second, especially for knee flexors (P <.001). The use of patellar tendon grafts was associated with lower F0 and a less steep F–V slope compared with hamstring tendon grafts (P <.010). Conclusion: The isokinetic 2-point model assessing the F–V relationship provides additional and relevant insight for evaluating knee muscle strength after ACL-R. [ABSTRACT FROM AUTHOR]

In this narrative review, we explore developments in the field of computational musculoskeletal model personalization using the Physiome and Musculoskeletal Atlas Projects. Model geometry personalization; statistical shape modeling; and its impact on segmentation, classification, and model creation are explored. Examples include the trapeziometacarpal and tibiofemoral joints, Achilles tendon, gastrocnemius muscle, and pediatric lower limb bones. Finally, a more general approach to model personalization is discussed based on the idea of multiscale personalization called scaffolds. [ABSTRACT FROM AUTHOR]

Context: Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military. Design: Prospective cohort study. Methods: Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period. Results: A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94–1.14; P =.49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87–1.06; P =.47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02–1.10; P =.01), and the odds ratio was 1.02 (95% CI, 0.98–1.07; P =.29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus. Conclusions: Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine if hamstring-strain-injury risk factors related to muscle structure and morphology differed between rugby union players and controls. Methods: The biceps femoris long head (BFlh) fascicle length and passive muscle stiffness and relative and absolute muscle volume of knee flexors (KF) and extensors (KE) were measured in 21 male subelite rugby players and 21 male physically active nonathletes. Results: BFlh fascicle length was significantly longer (mean difference [MD] = 1.6 [1.7] cm) and BFlh passive muscle stiffness was significantly higher in rugby players (MD = 7.8 [14.8] kPa). The absolute BFlh (MD = 71.9 [73.3] cm3), KF (MD = 332.3 [337.2] cm3), and KE (MD = 956.3 [557.4] cm3) muscle volumes were also significantly higher in rugby players. There were no significant differences in the relative BFlh and KF muscle volumes. The relative KE muscle volumes were significantly higher in rugby players (MD = 2.3 [3.7] cm3/kg). However, the percentage BFlh fascicle length:KE (MD = −0.1% [0.1%]), BFlh/KE (MD = −0.9% [1.9%]), and KF:KE (MD = −4.9% [5.9%]) muscle volume ratios were significantly lower in the rugby players. BFlh muscle volume significantly correlated with BFlh fascicle length (r =.59, r2 =.35) and passive muscle stiffness (r =.46, r2 =.21). Conclusion: Future prospective studies should examine whether there are threshold values in BFlh passive muscle stiffness and BFlh fascicle length:KE, BFlh:KE, and KF:KE muscle volume ratios for predicting hamstring strain injuries. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine i) pain phenotypes (PP) in people with early-stage knee osteoarthritis (EKOA); ii) the longitudinal association between the phenotypes and pain worsening at two years. DESIGN: We studied participants with EKOA from the Multicenter Osteoarthritis Study defined as pain intensity ≤3/10, Kellgren and Lawrence grade ≤2, intermittent pain none to sometimes, and no constant pain. Two models of PP were explored. Model A included pressure pain thresholds, temporal summation, conditioned pain modulation, pain catastrophizing, sleep quality, depression, and widespread pain (WSP). In Model B, gait characteristics, quadriceps strength, comorbidities, and magnetic resonance imaging features were added to Model A. Latent Class Analysis was used to create phenotypes, and logistic regression was used to determine their association with pain worsening. RESULTS: 750 individuals (60% females), mean age [standard deviation (SD)]: 60.3 (9.4) were included in Model A and 333 individuals (60% females), mean age (SD): 59.4 (8.1) in Model B. 3-class and 4-class solutions were chosen for Model A and Model B. In Model A, the most severe phenotype was dominated by psychosocial factors, WSP, and measures of nervous system sensitization. Similarly in Model B, the Model A phenotype plus gait variables, quadriceps strength, and comorbidities were dominant. Surprisingly, none of the phenotypes in either model had a significant relationship with pain worsening. CONCLUSION: Phenotypes based upon various factors thought to be important for the pain experience were identified in those with EKOA but were not significantly related to pain worsening. These phenotypes require validation with clinically relevant endpoints.

BackgroundObesity influences the development of osteoarthritis via low-grade inflammation. Progression of local inflammation (= synovitis) increased with weight gain in overweight and obese women compared to stable weight. Synovitis could be associated with subcutaneous fat (SCF) around the knee. Purpose of the study was to investigate the effect of weight loss on synovitis progression and to assess whether SCF around the knee mediates the relationship between weight loss and synovitis progression.MethodsWe included 234 overweight and obese participants (body mass index [BMI] ≥ 25 kg/m2) from the Osteoarthritis Initiative (OAI) with > 10% weight loss (n = 117) or stable overweight (

BACKGROUND: The incidence of medial collateral ligament injuries in the knee joint is easy to lead to secondary meniscus and cartilage damage, and longterm chronic damage can lead to the occurrence of osteoarthritis. At present, there are few studies on the mechanics of meniscus and articular cartilage injury caused by medial collateral ligament rupture. OBJECTIVE: To investigate the effect of different degrees of medial collateral ligament injury on the biomechanics of meniscus and cartilage of knee joint. METHODS: The CT and MRI examinations of the knee joint of a healthy volunteer were performed to obtain the image data. The scanning data were imported into Mimics, Geomagic, and Solidworks software in turn. After registration and fusion, a 3D model of normal knee joint was established. On this basis, models of medial collateral ligament injury in different degrees of knee joint were simulated, which were divided into four groups, including: (1) medial collateral ligament was intact; (2) deep medial collateral ligament fracture; (3) superficial medial collateral ligament fracture; (4) complete rupture of medial collateral ligament. Finally, Ansys software was introduced to apply three modes of loads to the knee joint: (1) 10 N·m valvaration torque was applied to the top of the femur. (2) A 4 N·m internal torque was applied to the top of the femur. (3) A 4 N·m external torque was applied to the top of the femur. The effects of four groups of models on knee biomechanics under different loads were analyzed. RESULTS AND CONCLUSION: (1) In the extension position of the knee joint, when a 10 N·m valgus torque was applied to the knee joint, the overall stress of the posterolateral meniscus increased with different degrees of medial collateral ligament injuries, while the stress of the articular cartilage did not change significantly. The peak stress of the posterolateral meniscus increased significantly with superficial medial collateral ligament rupture. (2) In the knee extension position, when a 4 N·m internal rotation torque was applied to the knee joint, the overall stress of the medial and lateral meniscus increased after different degrees of medial collateral ligament injury. When superficial medial collateral ligament rupture occurred, the peak stress of the meniscus shifted from the anterior horn of the medial meniscus to the anterior horn of the lateral meniscus. (3) In the knee extension position, applying a 4 N·m external rotation torque to the knee joint, the peak stress of the posterolateral meniscus increased more significantly than that of the medial meniscus, and the stress of the articular cartilage changed less. (4) These results show that the risk of meniscus injury secondary to superficial medial collateral ligament rupture is much higher than that of deep medial collateral ligament rupture when the knee is in extension, and the lateral meniscus is more vulnerable to injury than the medial meniscus. Both superficial medial collateral ligament and deep medial collateral ligament play an important role in the rotational stability of the knee joint. [ABSTRACT FROM AUTHOR]

Background: Accurate measurement of the hip-knee-ankle (HKA) angle is essential for informed clinical decision-making in the management of knee osteoarthritis (OA). Knee OA is commonly associated with varus deformity, where the alignment of the knee shifts medially, leading to increased stress and deterioration of the medial compartment. The HKA angle, which quantifies this alignment, is a critical indicator of the severity of varus deformity and helps guide treatment strategies, including corrective surgeries. Current manual methods are labor-intensive, time-consuming, and prone to inter-observer variability. Developing an automated model for HKA angle measurement is challenging due to the elaborate process of generating handcrafted anatomical landmarks, which is more labor-intensive than the actual measurement. This study aims to develop a ResNet-based deep learning model that predicts the HKA angle without requiring explicit anatomical landmark annotations and to assess its accuracy and efficiency compared to conventional manual methods. Methods: We developed a deep learning model based on the variants of the ResNet architecture to process lower limb radiographs and predict HKA angles without explicit landmark annotations. The classification performance for the four stages of varus deformity (stage I: 0°–10°, stage II: 10°–20°, stage III: > 20°, others: genu valgum or normal alignment) was also evaluated. The model was trained and validated using a retrospective cohort of 300 knee OA patients (Kellgren-Lawrence grade 3 or higher), with horizontal flip augmentation applied to double the dataset to 600 samples, followed by fivefold cross-validation. An extended temporal validation was conducted on a separate cohort of 50 knee OA patients. The model's accuracy was assessed by calculating the mean absolute error between predicted and actual HKA angles. Additionally, the classification of varus deformity stages was conducted to evaluate the model's ability to provide clinically relevant categorizations. Time efficiency was compared between the automated model and manual measurements performed by an experienced orthopedic surgeon. Results: The ResNet-50 model achieved a bias of − 0.025° with a standard deviation of 1.422° in the retrospective cohort and a bias of − 0.008° with a standard deviation of 1.677° in the temporal validation cohort. Using the ResNet-152 model, it accurately classified the four stages of varus deformity with weighted F1-score of 0.878 and 0.859 in the retrospective and temporal validation cohorts, respectively. The automated model was 126.7 times faster than manual measurements, reducing the total time from 49.8 min to 23.6 sec for the temporal validation cohort. Conclusions: The proposed ResNet-based model provides an efficient and accurate method for measuring HKA angles and classifying varus deformity stages without the need for extensive landmark annotations. Its high accuracy and significant improvement in time efficiency make it a valuable tool for clinical practice, potentially enhancing decision-making and workflow efficiency in the management of knee OA. [ABSTRACT FROM AUTHOR]

This study aimed to analyze and predict various types of knee pain in knee osteoarthritis (KOA) patients based on Semi-Quantitative MRI Osteoarthritis Knee Score (SQ-MOAKS) features. The goal was to identify structural abnormalities in the knee joint associated with different types of pain, thereby aiding in the development of personalized treatment plans. Subjects were selected from the Osteoarthritis Initiative (OAI) database, including 297 patients who underwent both SQ-MOAKS assessment on knee MRI images and WOMAC knee pain assessment. Univariate and multivariate logistic regression analyses were used for feature selection, followed by the construction of multi-risk factor models and corresponding nomograms for each pain type. The predictive values of the models were evaluated using ROC curves and related metrics (AUC, accuracy, sensitivity, specificity), and the DeLong test was used to assess the significance of differences between various ROCs and AUCs. Significant associations were found between specific SQ-MOAKS features and different types of knee pain. Bone marrow lesions (BML) and cartilage morphology (CM) features were crucial in predicting the walking pain and rest pain, while osteophytes (OS) were more associated with nocturnal pain and pain during stair climbing. The models demonstrated high predictive accuracy, particularly for walking pain and rest pain. This study demonstrated that SQ-MOAKS features could effectively predict different types of knee pain, revealing the structural basis of knee pain in KOA patients. These results prompted the use of SQ-MOAKS in developing personalized treatment strategies, enhancing clinical decision-making, and improving patient quality of life. [ABSTRACT FROM AUTHOR]

Background: Combining arthroscopic microfractures (MF) with platelet-rich plasma (PRP) complexes is a potential approach for treating knee cartilage injuries. However, effective treatment of cartilage injuries in the knee joint remains a challenge. Objective: To evaluate the clinical effects of a platelet-rich complex based on MF surgery for treating knee cartilage injuries. Methods: We selected 120 patients with knee cartilage injury and divided them into observation and experimental groups according to the use of a platelet-rich complex. Preoperative and postoperative follow-up visit data were retrospectively collected and analyzed. Results: Preoperative visual acuity scores between the two groups were comparable (P>0.05). At 3 and 6 months postoperatively, the scores were lower in the experimental group than in the control group (P<0.05). The preoperative Lysholm knee scores and Tegner activity were similar (P>0.05) but greater in the experimental group at 3 and 6 months postoperatively (P<0.05). Postoperative complications were similar between the two groups according to Fisher’s exact test (P=1.00). Conclusion: The platelet-rich complex based on MF surgery treatment of knee cartilage injuries exhibited a better clinical effect and is an easy-to-operate and effective method worthy of clinical consideration. [ABSTRACT FROM AUTHOR]

Osteoporosis (OP) is the most prevalent and common bone disease, especially knee osteoporosis. It significantly disables sufferers all over the world. Although laborious and prone to user variation, manual diagnosis, segmentation, and annotation of knee joints continue to be the preferred way to diagnose OP in clinical procedures. Therefore, many deep learning algorithms, particularly the convolutional neural network (CNN), have been created to increase clinical workflow efficiency to overcome the shortcomings of the widely used method as above. Medical imaging procedures can show hidden structures in a volumetric view, particularly those that generate three-dimensional (3D) pictures like MRI. We created a dataset of 240 pictures from patients who had knee X-rays and skeletal bone mineral density assessments at the same time. Four convolutional neural networks (CNN) models were used to analyse the X-ray images and deep neural networks for clinical covariances to determine the degree of osteoporosis. Additionally, we investigated ensemble models that included each CNN with a clinical covariance. For every network, scores for accuracy and error rate were computed. ResNet and Alexnet displayed the highest levels of accuracy when the CNN models were tested using knee X-rays with normal, low BMD, and osteoporosis. An ensemble of DNN with Alexnet, ResNet, and both ResNet and Alexnet are employed resulting in improved accuracy. The ensemble of best-performing CNN and DNN is proposed to diagnose osteoporosis more accurately. The proposed method has produced a highly accurate osteoporosis diagnosis. [ABSTRACT FROM AUTHOR]

Background Landing with poor knee sagittal plane biomechanics has been identified as a risk factor for Anterior Cruciate Ligament (ACL) injury. However, it is unclear if the horizontal hop test battery reflects knee function and biomechanics. Hypothesis/Purpose To investigate the correlation between clinical limb symmetry index (LSI) and landing and propulsion knee biomechanics during the hop test battery using markerless motion capture. Study Design Cross-sectional biomechanics laboratory study Methods Forty-two participants with and without knee surgery (age 28.0 ± 8.0 years) performed the hop test battery which consisted of a single hop for distance, crossover hop, triple hop, and 6-m timed hop in the order listed. Eight high speed cameras were used to collect simultaneous 3D motion data and Theia 3D (Theia Markerless Inc.) was used to generate 3D body model files. Lower limb joint kinematics were calculated in Visual3D. Correlation (Spearman's ρ) was computed between clinical LSI and symmetry in peak and initial contact (IC) knee flexion angle during propulsion and landing phases of each movement. Results In the single hop, clinical LSI showed positive correlation with kinematic LSI at peak landing (ρ= 0.39, p=0.011), but no correlation at peak propulsion (ρ= -0.03, p=0.851). In the crossover hop, non-significant correlations were found in both propulsion and landing. In the triple hop, positive correlation was found at peak propulsion (ρ= 0.38, p=0.027), peak landing (ρ= 0.48 -- 0.66, p<0.001), and last landing IC (ρ= 0.45, p=0.009). In the timed hop, peak propulsion showed positive correlation (ρ= 0.51, p=0.003). Conclusions Single hop and triple hop distance symmetry reflected landing biomechanical symmetry better than propulsion symmetry. Poor scores on the hop test battery reflect asymmetrical knee landing biomechanics, emphasizing the importance of continuing to use the hop test battery as part of clinical decision making. Level of Evidence 3b [ABSTRACT FROM AUTHOR]

Purpose: To develop a comprehensive and validated personalized scoring system based on anatomical characteristics to predict the probability of failure to return to sport after medial patellofemoral ligament reconstruction in patients with patellar dislocation. Methods: 312 patients with medial patellofemoral ligament reconstruction in our hospital from 2013 to 2023 were included. Demographic and anatomical characteristics were collected retrospectively. A backward stepwise approach was used to identify independent predictors, and a nomogram was constructed to predict the probability of recurrence. The predictive performance was evaluated by receiver operating characteristic curves, calibration diagram and decision curve analysis. Results: Multivariate analysis showed that increased tibial tubercle–trochlear groove (TT-TG) distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta were independent risk factors for failure of return to sport after medial patellofemoral ligament reconstruction. Validation of this column graph in the training cohort and validation cohort showed strong predictive power, with areas under the curve of 0.850 and 0.844, respectively. The nomogram has good calibration and good clinical practicability. Conclusion: The study developed a personalized predictive nomogram with 4 predictors (increased TT-TG distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta) that allowed surgeons to stratify the risk of failure to return to sport after medial patellofemoral ligament reconstruction and recommend skeletal surgery for patients with these factors. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Background: Periarticular local infiltration analgesia (LIA) has become a widely used method for postoperative pain management after unicompartmental knee arthroplasty (UKA). However, the efficacy of using magnesium sulphate or sodium bicarbonate in LIA cocktails during UKA is not yet clear. The present study aimed to evaluate whether the modified LIA has advantages in pain control and joint function recovery after UKA surgery. Methods: Sixty-one patients who underwent UKA were enrolled and randomly assigned to receive periarticular infiltration of a modified cocktail (comprising ropivacaine, epinephrine, dexamethasone, magnesium sulphate, and sodium bicarbonate) or a conventional cocktail (comprising ropivacaine, epinephrine, dexamethasone, ketorolac, and morphine). The outcomes included the consumption of patient-controlled intravenous analgesia (PCIA) medication used for postoperative analgesia, pain score, early joint functional recovery, discharge time, and complication rates. Results: In the first 12 h after surgery, the conventional cocktail was not superior to the modified cocktail in terms of visual analogue scale (VAS) scores. However, beginning on the second postoperative day, the analgesic effect was significantly prolonged in the modified group, leading to lower VAS scores and better knee functional recovery. Additionally, patients in the modified group required less pain medication via PCIA, both within the first 24 h and cumulatively up to 48 h after surgery. Both groups had similar rates of complications. Conclusions: The present modification of a conventional cocktail significantly prolonged the analgesic effect and reduced pain medication consumption after UKA surgery, which was associated with better functional recovery in the early postoperative days. Trial registration: Chinese Clinical Trial Registry, ChiCTR2200060500. 21 March 2023. [ABSTRACT FROM AUTHOR]

Total knee arthroplasty (TKA) is a widely performed surgical intervention designed to relieve pain and restore function in patients with severe knee joint degeneration, most commonly due to osteoarthritis. This procedure involves replacing the damaged knee joint with a prosthetic implant, providing significant improvements in mobility and quality of life. While TKA is beneficial for many, the individuals who stand to gain the most are those with advanced knee arthritis unresponsive to conservative treatments, typically aged 60 and above, experiencing activity‐related pain and functional limitations. Identifying patients with the highest potential for positive outcomes is critical to maximizing the benefits of this transformative surgery. Goal of this editorial is to give a critical view on today's common practice of arthroplasty surgery. [ABSTRACT FROM AUTHOR]

The study aimed to clarify the difference in the support leg dynamics and its mechanical role in producing the interaction torque acting on the kicking leg knee between female and male soccer players. Three-dimensional motion (500 Hz) and the ground reaction force (1000 Hz) were captured during the instep kicking of twenty female and twenty male players. Powers due to the support leg knee joint torque and the interaction torque were computed. A significantly smaller positive power of the interaction torque due to the support leg action seen in female players concurred with a significantly smaller positive knee joint power in the support leg. In contrast, female players exhibited a comparable positive power of the interaction torque due to the kicking leg action. Female players had a unique, more inclined lower leg posture of the kicking leg to compensate for their lesser power of the interaction torque due to the support leg action, thereby achieving a comparable magnitude of the power of the total interaction torque. Based on the dynamic background, they maintain a comparable lower leg angular velocity to that of male players immediately before ball impact. [ABSTRACT FROM AUTHOR]

High jump is a power-demanding motor task. Jumpers extend the take-off leg joints with maximum effort, but kinetic requirements (i.e. torque/power) for each joint are unclear. Here we show the inter-joint differences in the kinetic exertion related to the flight height in high jump trials by 16 male high jumpers (personal best record: 1.90–2.35 m). For the knee joint, both maximum net power and maximum norm of torque were significantly and positively correlated with flight height, with a stronger correlation for maximum net power (r = 0.70) than for maximum norm of torque (r = 0.52). For the hip joint, maximum norm of torque was significantly correlated with flight height (r = 0.62), but maximum net power (r = 0.36) was not. Both torque and power exhibited the proximal-to-distal sequence (from hip to ankle). The norm of ground reaction force peaked almost simultaneously with the hip torque while external net power peaked with knee power. We suggest that the required musculoskeletal function of each joint differs even in the same task. We suggest that it may be effective to adapt the different training programme between joints to improve performance. Jumpers should prioritise torque exertion for the hip and power exertion for the knee. [ABSTRACT FROM AUTHOR]

Conventional low-pass filtering of 3D motion capture signals prior to estimating knee joint moments and ACL injury risk has known limitations. This study aimed to evaluate the fractional Fourier filter (FrFF), which employs a time-varying cut-off frequency, for assessing peak knee moments during common ACL injury risk screening tasks. Ground reaction force and motion data were collected from 23 team sport athletes performing 45° unanticipated sidesteps and drop jumps. Peak knee abduction, internal rotation and non-sagittal moments were estimated using inverse dynamics after five different low-pass filter approaches were applied (FrFF vs. four variations of a fourth-order Butterworth filter). The FrFF produced peak knee moments larger than "matched" (i.e. force and motion cut-off frequencies were equivalent) and closer to "unmatched" (i.e. force and motion cut-offs were different) Butterworth filter approaches and removed problems with representing foot-to-ground impact peaks. Participants with larger peak moments were identified as "at risk" of injury irrespective of filter approach, but the FrFF identified "at risk" classifications conventional approaches did not. Preliminary evidence suggests that the FrFF displays enhanced sensitivity to movement strategies that induce high knee loads. This was most evident for sidestepping, with more research warranted to optimise the FrFF for drop jumps. [ABSTRACT FROM AUTHOR]

Background: While measuring meniscal extrusion quantitatively is an early risk factor for knee osteoarthritis (KOA), the biomechanics involved in this process are not well understood. This study aimed to investigate the effects of varying degrees of medial and lateral meniscal extrusion and their material softening on knee osteoarthritis progression. Methods: Finite element analysis (FEA) was utilized to simulate varying degrees of meniscal extrusion (1–5 mm) in 72 knee joint models, representing progressive meniscal degeneration and material softening due to injury. Changes in von Mises stress of the cartilage and menisci and the load distribution on the tibial plateau's meniscus and cartilage were studied under balanced standing posture in both healthy and injured knees, and statistical analysis was performed using Spearman correlation. Results: Compared to healthy knees, peak stress in medial compartment tissues increased by over 40% with 4 mm of medial meniscus extrusion, and in lateral compartment tissues with 2 mm of lateral meniscus extrusion. Meniscus extrusion reduced the contact load between the meniscus and femoral cartilage but increased it between the tibial and femoral cartilages, with a maximum increase up to fivefold. Spearman correlation analysis indicated that meniscal extrusion significantly affected peak stress and contact loads in the respective knee compartment (p < 0.001), with a lesser impact on the opposite compartment. Notably, medial meniscal extrusion also significantly increased peak stress in the lateral tibial cartilage (p < 0.05). Conclusions: The quantitative analysis revealed that meniscal extrusion significantly affected the biomechanics of soft tissues within the same compartment, with limited impact on the opposite side. Specifically, Medial extrusion beyond 4 mm significantly affected the biomechanics of the medial compartment, while lateral extrusion over 2 mm had a similar impact on the lateral compartment. Meniscal softening, without altering joint contact characteristics, primarily affected the biomechanics of the meniscus itself, with minimal impact on other soft tissues. [ABSTRACT FROM AUTHOR]

A major barrier that hampers our understanding of the precise anatomic distribution of pain sensing nerves in and around the joint is the limited view obtained from traditional two dimensional (D) histological approaches. Therefore, our objective was to develop a workflow that allows examination of the innervation of the intact mouse knee joint in 3D by employing clearing‐enabled light sheet microscopy. We first surveyed existing clearing protocols (SUMIC, PEGASOS, and DISCO) to determine their ability to clear the whole mouse knee joint, and discovered that a DISCO protocol provided the optimal transparency for light sheet microscopy imaging. We then modified the DISCO protocol to enhance binding and penetration of antibodies used for labeling nerves. Using the pan‐neuronal PGP9.5 antibody, our protocol allowed 3D visualization of innervation in and around the mouse knee joint. We then implemented the workflow in mice intra‐articularly injected with nerve growth factor (NGF) to determine whether changes in the nerve density can be observed. Both 3D and 2D analytical approaches of the light sheet microscopy images demonstrated quantifiable changes in midjoint nerve density following 4 weeks of NGF injection in the medial but not in the lateral joint compartment. We provide, for the first time, a comprehensive workflow that allows detailed and quantifiable examination of mouse knee joint innervation in 3D. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence This study aimed to assess the short‐term clinical efficacy of combining posterior meniscal root repair with meniscal centralization technology in the treatment of medial meniscus posterior root tears (MMPRTs) and notable meniscus extrusion.In this retrospective analysis, patients aged 43–76 years with only chronic posterior root tears of the medial meniscus and notable extrusion were followed up for 12–14 months. Inclusion criteria: (1) persistent medial knee joint pain affecting daily life, presenting with joint space tenderness; (2) showing the ineffectiveness of conservative treatment for a minimum of 3 months; conservative treatment includes non‐invasive methods such as nonsteroidal anti‐inflammatory drugs, physical therapy and massage, but does not include intra‐articular injections. (3) Kellgren–Lawrence Grades 0–II osteoarthritis (OA) of the knee joint; and (4) diagnosis of a posterior root tear of the medial meniscus with notable meniscus extrusion confirmed through knee‐joint plain magnetic resonance imaging (MRI) scans, where coronal image revealed a meniscus body extrusion of ≥3 mm. Exclusion criteria: (1) Kellgren–Lawrence Grades III–IV OA in the knee joint; (2) presence of knee joint infection or other structural damage to the knee joint; (3) history of previous knee joint surgery; (4) demonstrating joint instability or abnormal lower‐limb alignment (varus deformity >5°); and (5) presence of severe mental illness, coagulation disorders, or other serious medical conditions. The Lysholms score, the Hospital for Special Surgery (HSS) knee score, the visual analogue scale (VAS) score and meniscal extrusion values were evaluated before and after surgery in 23 patients through a comparative analysis.The results of the follow‐up conducted 12–14 months post‐operatively indicated a significant improvement in the patients' conditions. In particular, the Lysholms scores (preoperative: 50.9 ± 10.2; 1‐year post‐surgery: 72.0 ± 8.4), HSS knee scores (preoperative: 45.9 ± 10.6; 1‐year post‐surgery: 79.1 ± 11.1) and VAS scores (preoperative: 4.0 ± 1.1; 1‐year post‐surgery: 0.9 ± 0.7) exhibited notable enhancements. Furthermore, compared to the preoperative values, the degree of meniscus extrusion measured by coronal MRI of the knee joint significantly improved post‐operatively (preoperative: 3.7 ± 0.8 mm; 1‐year post‐surgery: 2.2 ± 0.6 mm). These findings all yielded a p < 0.05, signifying statistical significance.In patients with chronic MMPRTs and notable extrusion, a combination of posterior meniscal root repair and centralization technology can effectively restore meniscus function and rectify the medial meniscus displacement, resulting in favourable short‐term clinical outcomes.Level IV. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is the most common joint disease, which mainly damages articular cartilage and involves the whole joint tissue. It has the characteristics of long course, repeated symptoms and high disability rate, and the incidence trend is gradually increasing. Tetramethylpyrazine (TMP) is the main alkaloid active substance in Ligusticum wallichii, a traditional Chinese medicine, which has the effect of promoting blood circulation and dredging collaterals, and has a good effect on the treatment of early OA, but its molecular mechanism has not been fully clarified so far. Based on network pharmacology, molecular docking simulation and animal experiments, this study explored the target and molecular mechanism of TMP in the treatment of OA. Methods: We used PubChem, SwissTargetPrediction, and PharmMapper databases to predict the molecular structure and potential targets of TMP. GeneCards and DisGeNET databases were used to predict the relevant targets of OA. Apply UniProt database to convert targets into unified gene names, and proofread and remove duplicate gene names. The intersection targets of TMP and OA obtained on venny2.1.0 website were submitted to the STRING database to construct a PPI network. CytoScape 3.8.2 software was used to analyze the PPI network and obtain the sub-network modules and 10 key targets. The intersection targets of TMP and OA were analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment using DAVID 6.8 database. The intersecting targets of TMP and OA, the biological process of GO enrichment, and KEGG signaling pathway were imported into Cytoscape 3.8.2 software to construct the TMP-target-pathway network diagram. Use molecular docking technology to simulate the interaction between TMP molecules and key targets, and predict the binding mode and binding ability. Animal models of rabbit knee osteoarthritis were prepared, and magnetic resonance imager (MRI) and fluorescence quantitative PCR (RT-qPCR) were used to observe the effect of TMP in treating OA as well as the expression of key target genes. Results: 585 potential targets of TMP, 3,857 potential targets of OA, and 49 intersecting targets of TMP and OA were obtained. The top 10 key target genes were obtained, in order of ranking: ALB, ESR1, IL10, CAT, F2, MPO, C3, CYP3A4, CYP2C9, ANXA1. GO and KEGG analysis implied that the key targets might act on OA by affecting endothelial cell permeability, peri-articular microcirculatory status, NETs production, activation of complement system and coagulation pathway, regulation of immune function of macrophages and T cells, and substance metabolism pathway in vivo , etc. The molecular mechanism might involve the formation of neutrophil extracellular trap, regulation of the actin cytoskeleton, complement and coagulation cascades, and T cell receptor signaling pathways, etc. Molecular docking simulations showed that the binding energy of IL10 and ANXA1 to TMP was greater than -5Kal/mol, but the other key target proteins showed better binding to TMP, and the binding energy was less than -5 kcal/mol. Animal experiments showed that TMP had a significant therapeutic effect on OA. The TMP group had significantly reduced knee joint effusion and bone marrow damage compared to the OA group (p < 0.05). The qRT-PCR results showed that compared with the OA group, the mRNA expression of ESR1, CAT, C3, CYP3A4, CYP2C9, and ANXA1 in the TMP group increased (p < 0.05), while there was no significant difference in mRNA expression of ALB, IL-10, F2, MPO, etc. (p > 0.05). Conclusion: TMP is effective in the treatment of OA, with multi-target and multi-pathway interactions. ESR1, CAT, C3, CYP3A4, CYP2C9, and ANXA1 may be potential targets for TMP treatment of OA. The molecular mechanism mainly involves the formation of neutrophil extracellular trap, regulation of the actin cytoskeleton, complement and coagulation cascades, and T cell receptor signaling pathways, etc. [ABSTRACT FROM AUTHOR]

This study aimed to meticulously assess the effectiveness of hyaluronic acid (HA) in mitigating symptoms associated with monosodium iodoacetate (MIA)-induced osteoarthritis (OA) symptoms in rodent models and to investigate the underlying mechanistic pathways. Eight-week-old rats were randomly allocated to a normal control group and three experimental groups (n = 10 per group). The normal group did not undergo any treatment. The experimental groups were administered MIA for 1 week to induce osteoarthritis, and orally administered distilled water (control group), 2 mg/kg indomethacin (INDO group), or 20 mg/kg HA (HA20 group) daily for 4 weeks. The HA20 group showed a significant improvement in hind-paw weight-bearing distribution after 4 weeks compared to the control group. HA suppressed inflammatory responses by reducing the overproduction of prostaglandin E2 and leukotriene B4 and protected the vital components of the articular ECM, including glycosaminoglycans and aggrecan. HA treatment effectively reduced inflammation, protected cartilage by inhibiting MMP expression, and suppressed inflammatory mediator production. This study demonstrates that HA has potential to alleviate OA symptoms in a rodent model stimulated with MIA, rendering it a promising therapeutic agent for OA. [ABSTRACT FROM AUTHOR]

Purpose: Pain following arthroscopic knee surgery remains a controversial clinical problem. Intra-articular (IA) glucocorticoid injections have demonstrated the potential to provide better analgesia in some orthopedic surgeries; however, due to the lack of studies, its role in knee arthroscopies remain unclear. This systematic review aimed to evaluate the efficacy and safety of intra-articular glucocorticoids after arthroscopic knee surgery. Methods: A systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guideline, with literature search performed on Medline, Embase, and the Cochrane Library. This systematic review has been registered with the International Prospective Register of Systematic Reviews (PROSPERO; ID: CRD42024509749). Inclusion criteria included randomized controlled trials published in English comparing IA glucocorticoid to placebo in patients undergoing knee arthroscopy. Risk of bias for all included studies was assessed using the Cochrane Collaboration's risk of bias tool. Clinical outcomes compared were pain score: visual analogue scale (VAS) or International Knee Documentation Committee (IKDC), time to first analgesia requirement, analgesia consumption, range of motion (ROM), patient satisfaction, and complications. Results: A total of 7 studies (3 and 4 with evidence level I and II, respectively) involving 309 patients were included. All studies showed that IA glucocorticoids significantly decreased subjective pain scores. Three studies showed significantly longer duration to first postoperative analgesia use, while 6 showed significantly reduced postoperative analgesic administration with IA glucocorticoid use. Two studies showed significantly increased patient satisfaction with IA glucocorticoid (P = 0.001 and P = 0.01, respectively). No studies showed significant differences in complications such as nausea, vomiting, bradycardia, hypotension, or procedure-related adverse effects between the groups. Conclusion: Current available randomized controlled trials suggest that IA glucocorticoids can significantly reduce postoperative pain, delay, and minimize postoperative analgesia use, and improve patient satisfaction. No postoperative complications or adverse events were reported, reflecting its safety as a postoperative analgesic modality. [ABSTRACT FROM AUTHOR]

Background: Manipulation under anesthesia (MUA) has been recommended for refractory arthrofibrosis after anterior cruciate ligament (ACL) reconstruction. However, the effectiveness of MUA to restore normal kinematics of the arthrofibrotic knee is still unclear. The objective of this study was to evaluate tibiofemoral and patellofemoral kinematics in six degrees-of-freedom (6DOF) in patients with arthrofibrosis before and after MUA. Methods: Computed tomography and dual fluoroscopic imaging system were used to assess in vivo knee kinematics. Ten patients (6 women and 4 men; 32.6 ± 6.5y, 168.4 ± 7.8 cm, 61.8 ± 13.2 kg) were included in this study. The tibiofemoral and patellofemoral kinematics in 6DOF were collected before and one year after MUA. A simple analysis of variance was used to evaluate kinematic data of preoperative arthrofibrotic knee, postoperative arthrofibrotic knee, and the contralateral knee. Results: The patella in the postoperative arthrofibrotic knee shifted significantly more inferiorly compared to the preoperative knee at 45° (P = 0.010), 60° (P = 0.008), and 75° (P = 0.049) of flexion. The patellar flexion in the postoperative arthrofibrotic knee significantly increased at 45° (P = 0.048), 60° (P = 0.037), and 75° (P = 0.006) of flexion compared to the preoperative arthrofibrotic knee. The patellar tilt was significantly decreased at 60° (P = 0.006) and at 75° (P = 0.037) of knee flexion in the postoperative arthrofibrotic knee compared to the contralateral knee. MUA significantly increased tibial internal rotation angle in the arthrofibrotic knee at 45° (P = 0.047), at 60° (P = 0.033), and at 75° (P = 0.021) of knee flexion. Conclusions: MUA could restore normal patellar inferior shift, flexion, and tibial rotation compared to the contralateral side. However, the MUA could not restore normal patellar tilt of the arthrofibrotic knee. This indicated that improvement of patellar tilt should be emphasized in postoperative rehabilitation. Highlights: The abnormal knee kinematics has been thought to be an important factor contributing to the associated joint degeneration in patients with arthrofibrosis after ACL reconstruction. Despite the effectiveness of MUA in the ROM gains for patients with knee arthrofibrosis, the effectiveness of MUA to restore normal knee kinematics in patients with arthrofibrosis after ACL reconstruction is still unclear. The MUA could restore normal patellar inferior shift, flexion, and tibial rotation. The MUA could not restore normal patellar tilt of the arthrofibrotic knee, indicating that improvement of patellar tilt should be emphasized in postoperative rehabilitation. [ABSTRACT FROM AUTHOR]

Non-invasive assessment of joint status using acoustic emissions (AE) is a growing research area that has the potential to translate into clinical practice. The purpose of this study is to investigate the correlation of the knee's AE with measures of proprioception, self-assessment, and performance, as it can be hypothesised that, AE parameters will correlate with joint function metrics due to AE being recorded during interaction of the articular surfaces. Threshold to detect passive motion (TTDPM), Knee Osteoarthritis Outcome Scores (KOOS) and 5 times sit-to-stand test (5STS) were collected from 51 participant. Knee AE were recorded during cycling with 30 and 60 rpm cadences using two sensors in different frequency ranges and three modes of AE event detection. Weak (0.297, p = 0.048) to moderate (0.475, p = 0.001) Spearman's correlations were observed between longer 5STS time and AE parameters (i.e. higher median absolute energy, signal strength, longer AE event rise time and duration). Similarly, AE parameters shown correlation with lower KOOS, especially in the "Function in Sports and Recreation" and "Activities of Daily Living" subscales with correlation coefficients for higher median amplitude up to 0.441, p = 0.001 and 0.403, p = 0.004, respectively. The correlation with the TTDPM was not detected for most of the AE parameters. Additionally, a lower frequency sensor and 60 rpm cadence AE recordings showed higher correlations. Considering that this study included subjects from the general population and the number of participants with KOOS <70 was relatively small, higher correlations might be expected for clinically confirmed OA cases. Additionally, different ICCs might be expected for alternative signal parameters and proprioception assessment methods. Overall, the study confirms that AE monitoring offers an additional modality of joint assessment that reflects interaction between cartilage surfaces and can complement orthopaedic diagnostics, especially in the context of remote monitoring, drug testing, and rehabilitation. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence Despite the clinical utility of the pivot shift exam, the requisite applied forces and torques to elicit a pivot shift remain unclear. The purposes of this study are (1) to identify the greatest forces and torques applied to the knee during the pivot shift exam and (2) to evaluate if the applied loads differ among experienced surgeons.Three cadaveric hemipelvis‐to‐toe specimens (ages 53, 36 and 31 years; two males and one female) with no history of knee or hip injury were utilized. The experimental setup consisted of securing the hemipelvis to a mounting frame via an external fixator to simulate patient positioning during the clinical exam. The hemipelvis, femur, and tibia were spatially tracked by motion capture and the applied loads were measured using a 6‐axis force‐torque sensor. After sectioning the anterior cruciate ligament (ACL), three board‐certified sports medicine surgeons then performed the pivot shift exam on each specimen utilizing their preferred technique. Forces (compression‐distraction, anterior‐posterior, and medial‐lateral) and torques (varus‐valgus, internal‐external rotation, and flexion‐extension) applied to the knee joint immediately preceding the reduction of the proximal lateral tibia during each pivot shift exam were calculated.Compression was the largest applied force averaging 95 N ± 15 N for all surgeons and knees, which was at least 4.5 times greater, on average, than the applied anterior and applied medial tibial forces (p < 0.0001). Valgus was the largest of the three applied torques, averaging 8.5 ± 2.1 Nm. Internal rotation torque was 3.7 times less, on average, than the applied valgus torque (p < 0.0001). Each surgeon applied compressive force. However, anterior force was more variable among surgeons, with one of the three surgeons applying minimal anterior force (p ≤ 0.024). The magnitude of applied torques was similar among examiners (n.s).Compressive force and valgus torque were the predominant applied loads during the pivot shift exam. A lower magnitude of internal rotation torque was also applied. The anterior force was not consistently applied among examiners. These data can better inform clinical, cadaveric, and computational studies utilizing the pivot shift exam to assess knee biomechanics and can be used to educate trainees in conducting this complex manoeuvre.An in vitro biomechanic study. [ABSTRACT FROM AUTHOR]