Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives

Criteria for knee flexion range of motion and quadriceps strength to ascend and descend stairs 1 year after bilateral total knee arthroplasty: A cross-sectional study

BackgroundStair ascent/descent pose significant challenges after total knee arthroplasty (TKA); however, the exact knee flexion range of motion (ROM) and quadriceps strength requirements remain unclear.ObjectiveTo establish criteria for knee flexion ROM and quadriceps strength to determine independence in stair ascent/descent and evaluate the accuracy of the combination of these factors in patients with bilateral TKA.MethodsPatients with bilateral TKA were cross-sectionally assessed at 1 year postoperatively for independence in stair ascent/descent. Receiver operating characteristic curves provided cutoff values for knee flexion ROM and quadriceps strength. The area under the curves (AUC) of each factor and logistic regression models including both factors were evaluated.ResultsEighty-two participants were included. Fifty-eight participants could independently ascend and 52 could descend stairs, with equal cutoff values for both: 121° for knee flexion ROM (AUC: 0.66 and 0.67) and 1.09 Nm/kg for quadriceps strength (AUC: 0.70 and 0.73). Logistic regression models produced AUCs of 0.73 and 0.76 for ascent and descent, respectively.ConclusionsA quadriceps strength of 1.09 Nm/kg is a useful cutoff for independent stair ascent/descent, but combining it with knee flexion ROM did not enhance accuracy. Other functions such as coordination of the knee or other joints may influence stair performance post-TKA.

Rethinking the Assessment of Arthrogenic Muscle Inhibition After ACL Reconstruction: Implications for Return-to-Sport Decision-Making-A Narrative Review

Arthrogenic muscle inhibition (AMI) is a neuromuscular impairment commonly observed following anterior cruciate ligament reconstruction (ACLR). This condition, characterized by persistent quadricep inhibition due to altered afferent feedback, significantly impacts neuromuscular recovery, delaying return to running and sport. Despite advancements in rehabilitation strategies, AMI may persist for months or even years after ACLR, leading to muscle strength asymmetries, altered biomechanics, and an increased risk of reinjury. The mechanisms underlying AMI involve both peripheral (joint effusion, mechanoreceptor dysfunction) and central (corticospinal inhibition, neuroplasticity alterations) components, which collectively hinder voluntary muscle activation and movement control. AMI alters gait mechanics, reduces knee stability, and promotes compensatory patterns that increase injury risk. Current return-to-sport protocols emphasize strength symmetry and functional performance but often neglect neuromuscular deficits. A comprehensive assessment integrating neuromuscular, biomechanical, and proprioceptive evaluations is needed at specific stages to optimize rehabilitation and minimize reinjury risk. Future research should explore targeted interventions such as neuromuscular stimulation, cognitive-motor training, and advanced gait analysis to mitigate AMI's impact and facilitate a safer, more effective return to sport.

Comparative analysis of isokinetic parameters in individuals with and without chondromalacia patellae

INTRODUCTION

Chondromalacia patella (CMP) is characterizsed by cartilage degeneration, affects young adults, more women (2:1) and is responsible for 75% of knee pain complaints in the active population. The etiology is multifactorial and may be related to extrinsic factors (trauma and burden) and intrinsic factors (patellar malalignment and quadriceps weakness). Isokinetic dynamometry (ID) can aid in the detection of the causal factors of knee pain related to CMP.

OBJECTIVES

To evaluate and compare the parameters of the ID of individuals with and without CMP and correlate them with the clinical aspects of individuals with CMP.

METHODS

This is a retrospective study that analyzed ID of the knee flexors and extensors, performed between 2013 and 2019 in the isokinetic dynamometry sector of the hospital. Six hundred ninety dynamometers tests were included, both sexes, aged between 14 and 59 years, divided into chondromalacia group (342) tests and control group (348) tests. All performed ID in concentric mode for knee extension and flexion, with five maximum repetitions at an angular speed of 60°/s and 180°/s and 20 repetitions at an angular speed of 300°/s, with 30-s intervals between each. After completing the test, the patient points out a number from 0 to 10 on the visual analog scale, regarding the presence and intensity of pain during and after the isokinetic assessment.

RESULTS

The groups had similar distribution from sex (P ​= ​0.071); age (P ​= ​0.99) but were different about pain (P ​< ​0.001). CMP had greater levels of pain. In most of the muscle parameters of the extensors and flexors at 60°/s were lower in the CMP group (P ​< ​0.001).

CONCLUSION

The main predictor of chondromalacia is pain. The greater coefficient of variability and time to reach peak torque on the involved side, the average power and morphology of the extensor curve can also be predictors of chondromalacia.

LEVEL OF EVIDENCE

III.

Effects of neuromuscular electrical stimulation on neuromuscular function and muscle quality in patient following anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstruction (ACLR) leads to quadriceps neuromuscular dysfunction, including impaired force control and muscle degradation. Neuromuscular electrical stimulation (NMES) is widely used in rehabilitation to improve muscle mass and strength; however, its effects on neuromuscular functions and muscle quality, such as motor unit (MU) behavior and force steadiness (FS), remain unclear. This study investigated the effects of NMES on neuromuscular function and muscle quality in individuals with ACLR who could walk normally. Ten male ACLR patients underwent NMES 3 times weekly for 6 weeks, with 30 contractions per session. Neuromuscular function was assessed via FS, maximum voluntary isometric contraction (MVIC), and MU behavior in the rectus femoris and vastus lateralis. Muscle quality was evaluated using muscle thickness (MT), echo intensity (EI), and ultrasound texture features. Measurements were taken at baseline and weeks 3 and 6. NMES significantly improved MVIC, FS, MU behavior, and muscle quality (MT, EI, and homogeneity) on the ACLR side, with significant interaction effects observed. At week 3, MVIC and FS showed no significant improvement; however, structural and qualitative muscle changes were evident. NMES effectively enhanced neuromuscular function, MU behavior, and muscle quality impaired by ACLR. However, a 3-week intervention may not be sufficient for optimal neuromuscular recovery, highlighting the need for extended NMES protocols.

Differences in vertical and lower-limb joint stiffness in RTS assessments between ACLR patients and non-injured controls

The aim of this study was to establish alterations in vertical and lower-limb joint stiffness following anterior cruciate ligament reconstruction (ACLR). 127 male patients 8-10 months post-ACLR and 45 non-injured controls performed unilateral and bilateral drop jumps, and cutting, while ground reaction forces (GRFs) and 3D kinematics were recorded. Stiffness and changes in vertical GRF were lower in ACLR patients during bilateral drop jumps compared to non-injured controls. ACLR patients also displayed lower knee stiffness in the bilateral drop jumps (d=-0.91, p < 0.001 and d = 0.53, p < 0.001, respectively) and cutting (d=-0.85, p < 0.001 and d = 0.19, p=0.040, respectively). In the unilateral drop jump, there were no differences in ankle, knee, or hip stiffness between groups, yet ACLR patients displayed smaller changes in knee moments (d=-0.63, p < 0.001) and decreased knee range of motion (d=0.44, p=0.013). During the bilateral drop jump, ACLR patients displayed lower ankle stiffness (d=0.46, p=0.003) and smaller ankle moment changes (d=0.48, p=0.006), compared to controls. Hence, joint level analysis provides practitioners with a more detailed insight into an athlete's movement strategy following ACLR than whole body analysis. Range of motion, change in moment, and stiffness of the knee joint especially, can help practitioners to assess fitness for return-to-sport in ACLR patients.

Number of conditioning trials, but not stimulus intensity, influences operant conditioning of brain responses after total knee arthroplasty

PURPOSE

The primary purpose of this randomized, cross-sectional study was to determine whether operant conditioning of motor evoked torque (MEPTORQUE) in individuals with total knee arthroplasty (TKA) increases quadriceps MEPTORQUE responses within a single session and induces acute corticospinal adaptations by producing sustained increases in MEPTORQUE after training. A secondary purpose was to determine if these changes were affected by the stimulus intensity and number of training trials.

METHODS

Thirty participants were block-randomized into one of three groups based on the participant's active motor threshold (100%, 120%, and 140%) to evaluate the effect of stimulus intensity. Participants received three blocks of conditioning trials (COND), where they trained to increase their MEPTORQUE. Control (CTRL) transcranial magnetic stimulation pulses were provided before and after each COND block to establish baseline corticospinal excitability and to evaluate the effect of the number of training trials. Two MEPTORQUE recruitment curves were collected to evaluate the effect of up-conditioning on acute corticospinal adaptations.

RESULTS

TKA participants were able to successfully increase their MEPTORQUE in a single session (F3,81 = 10.719, p < 0.001) and induce acute corticospinal adaptations (F1,27 = 20.029, p < 0.001), indicating sustained increases in quadriceps corticospinal excitability due to operant conditioning. While the stimulus intensity used during training did not affect the ability to increase MEPTORQUE (F2,26 = 0.021, n.s.) or its associated acute adaptations (F2,27 = 0.935, n.s.), the number of training trials significantly influenced these outcomes (F3,81 = 10.719, p < 0.001; F3,81 = 4.379, p = 0.007, respectively).

CONCLUSION

Operant conditioning is a feasible approach for improving quadriceps corticospinal excitability following TKA. While any of the three stimulus intensities evaluated in this study may be used in future operant conditioning interventions, using a low or moderate stimulus intensity and 150 training trials are recommended to improve treatment efficiency and patient adherence.

LEVEL OF EVIDENCE

Level II.

Nutritional Interventions to Attenuate Quadriceps Muscle Deficits following Anterior Cruciate Ligament Injury and Reconstruction

Following anterior cruciate ligament (ACL) injury, quadriceps muscle atrophy persists despite rehabilitation, leading to loss of lower limb strength, osteoarthritis, poor knee joint health and reduced quality of life. However, the molecular mechanisms responsible for these deficits in hypertrophic adaptations within the quadriceps muscle following ACL injury and reconstruction are poorly understood. While resistance exercise training stimulates skeletal muscle hypertrophy, attenuation of these hypertrophic pathways can hinder rehabilitation following ACL injury and reconstruction, and ultimately lead to skeletal muscle atrophy that persists beyond ACL reconstruction, similar to disuse atrophy. Numerous studies have documented beneficial roles of nutritional support, including nutritional supplementation, in maintaining and/or increasing muscle mass. There are three main mechanisms by which nutritional supplementation may attenuate muscle atrophy and promote hypertrophy: (1) by directly affecting muscle protein synthetic machinery; (2) indirectly increasing an individual's ability to work harder; and/or (3) directly affecting satellite cell proliferation and differentiation. We propose that nutritional support may enhance rehabilitative responses to exercise training and positively impact molecular machinery underlying muscle hypertrophy. As one of the fastest growing knee injuries worldwide, a better understanding of the potential mechanisms involved in quadriceps muscle deficits following ACL injury and reconstruction, and potential benefits of nutritional support, are required to help restore quadriceps muscle mass and/or strength. This review discusses our current understanding of the molecular mechanisms involved in muscle hypertrophy and disuse atrophy, and how nutritional supplements may leverage these pathways to maximise recovery from ACL injury and reconstruction.

Conditioning of Motor Evoked Responses After Anterior Cruciate Ligament Reconstruction: Effects of Stimulus Intensity

BACKGROUND

Operant conditioning of motor evoked torque (MEPTORQUE) can directly target the corticospinal pathway in patients with anterior cruciate ligament (ACL) reconstruction. However, it remains unclear whether operant conditioning can elicit short-term improvements in corticospinal excitability and whether these improvements are influenced by stimulus intensity.

HYPOTHESIS

Quadriceps MEPTORQUE responses can be upconditioned in a single session and will elicit short-term adaptations in corticospinal excitability, with higher stimulus intensities eliciting greater effects.

STUDY DESIGN

Randomized controlled laboratory study.

LEVEL OF EVIDENCE

Level 2.

METHODS

Thirty-six participants were assessed during a single session of an operant conditioning protocol. Participants were randomized into 1 of 3 groups for stimulus intensity used during operant conditioning based on the participant's active motor threshold (AMT: 100%, 120%, and 140%). Quadriceps MEPTORQUE amplitude was evaluated during a block of control transcranial magnetic stimulation trials (CTRL) to establish baseline corticospinal excitability, and 3 blocks of conditioning trials (COND) during which participants trained to upcondition their MEPTORQUE. MEPTORQUE recruitment curves were collected to evaluate the effect of operant conditioning on acute corticospinal adaptations.

RESULTS

Participants with ACL reconstruction could upcondition their MEPTORQUE in a single session (P < 0.01; CTRL, 17.27 ± 1.28; COND, 21.35 ± 1.28 [mean ± standard error [SE] in N·m]), but this ability was not influenced by the stimulus intensity used during training (P = 0.84). Furthermore, significant improvements in corticospinal excitability were observed (P = 0.05; PRE, 687.91 ± 50.15; POST, 761.08 ± 50.15 [mean ± SE in N·m %AMT]), but stimulus intensity did not influence corticospinal adaptations (P = 0.67).

CONCLUSION

Operant conditioning can elicit short-term neural adaptations in ACL-reconstructed patients. Future operant conditioning paradigms may effectively use any of the 3 stimulus intensities studied herein.

CLINICAL RELEVANCE

Operant conditioning may be a feasible approach to improve corticospinal excitability after ACL reconstruction.

Thigh muscle features in female patients with severe knee osteoarthritis: a cross-sectional study

BACKGROUND

Muscle function deterioration in female patients with severe knee osteoarthritis (KOA) is linked to alterations in muscle morphology, composition, and mechanical properties. This study evaluates thigh muscle features in female patients with severe KOA and explores correlations with knee joint function.

METHODS

Ultrasound and shear wave elastography measured physiological cross-sectional area (PCSA), echo intensity (EI), and shear modulus (G) in the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris long head (BFL), and semitendinosus (ST) of 24 KOA patients and 24 controls. EI indicates intramuscular fat, while G reflects stiffness. Muscle characteristics were compared between groups, and correlations with knee function scores (WOMAC, KSS, HSS) were analyzed.

RESULTS

In patients, the symptomatic side displayed reduced PCSA for RF, VL, VM, BFL, and ST (15.85[Formula: see text], 28.18[Formula: see text], 21.53[Formula: see text], 11.67[Formula: see text], 6.59[Formula: see text] respectively) vs. controls (19[Formula: see text], 36.32[Formula: see text], 23.37[Formula: see text], 14.15[Formula: see text], 7.12[Formula: see text] respectively). EI was elevated (128.95, 121.12, 105.72, 90.52, 93.15) vs. controls (100.39, 93.97, 88.14, 77.69, 78.73), and G values (9.48 kPa, 7.88 kPa, 6.9 kPa, 7.2 kPa, 9.03 kPa) was higher than controls (8.85 kPa, 5.28 kPa, 5.98 kPa, 6.58 kPa, 6.73 kPa). BFL`s G, ST`s G, and VM`s EI, negatively correlated with knee function, whereas BFL`s PCSA positively correlated. The variable importance of BFL's PCSA and G ranked at the top in all scores.

CONCLUSIONS

Compared to controls, PCSAs in muscles on both sides of KOA patients were lowered by up to 22%, indicative of muscle loss and diminished strength. The G value is 20.65% higher, suggesting poor flexibility and elevated passive tension. EI in muscles on both sides of KOA patients was greater, reaching up to 23.88%, possibly reducing contractile components and muscle force. G, PCSA, and EI are closely correlated with function scores, and PCSA and G of BFL are the most significant predictors of knee function. These results may help explain muscle dysfunction in KOA patients.

CLINICAL TRIAL NUMBER

Not applicable.

Neurophysiology of ACL Injury

The neurophysiology of ACL injury extends beyond the mechanical rupture of the ligament to encompass profound alterations in the central and peripheral nervous systems, impacting sensorimotor integration and neuromuscular control. The ACL, densely populated with mechanoreceptors, plays a critical role in joint proprioception, dynamically regulating knee stability through complex neural circuits that connect to the spinal cord and brain. When disrupted by injury, these neural pathways contribute to delayed muscular activation, altered motor planning, and compromised joint stability. Such neuromechanical deficits increase the likelihood of reinjury and highlight the need for comprehensive neuroplastic rehabilitation. Neuroplastic therapy, employing tools like external focus strategies, stroboscopic glasses, smartboards, and virtual reality, aims to restore and enhance neural connectivity, sensory integration, and motor coordination. These advanced tools target distinct phases of motor learning, promoting automaticity and resilience in movement patterns. By integrating visual-cognitive, proprioceptive, and reflexive controls, this therapeutic approach not only accelerates recovery but also optimizes performance and reduces the risk of re-injury, representing a paradigm shift in ACL rehabilitation.

Operant Upconditioning of the Quadriceps Motor Evoked Torque as a Means to Improve Quadriceps Function After ACL Reconstruction

BACKGROUND

Diminished corticospinal excitability is theorized to contribute to poor quadriceps function after anterior cruciate ligament (ACL) reconstruction. Operant conditioning of the motor evoked torque (MEPTORQUE) is a promising approach capable of improving corticospinal excitability. However, it is unknown whether increasing corticospinal excitability can improve quadriceps function after a short-term operant conditioning intervention in patients with reconstructed ACL.

HYPOTHESIS

After ACL reconstruction, patients would demonstrate increases in quadriceps strength, voluntary activation, and corticospinal excitability after a 2-week operant conditioning intervention.

STUDY DESIGN

Randomized controlled clinical trial.

LEVEL OF EVIDENCE

Level 1.

METHODS

A total of 22 patients with reconstructed ACL were randomized into 1 of 2 groups: group 1 received 2 weeks of operant conditioning training on the reconstructed leg to improve their transcranial magnetic stimulation (TMS)-elicited MEPTORQUE responses (COND); group 2 received 2 weeks of TMS only (SHAM-COND). Quadriceps strength, voluntary activation, and corticospinal excitability on the reconstructed leg were evaluated before and after the 2-week intervention. Within-session changes in corticospinal excitability were also evaluated during the training sessions.

RESULTS

The COND group demonstrated a significantly higher within-session percent increase in MEPTORQUE during training compared with the SHAM-COND group, paralleled by a significant increase in corticospinal excitability after the 2-week intervention. In addition, quadriceps strength and voluntary activation improved on the reconstructed leg after the 2-week intervention, regardless of group.

CONCLUSION

Operant conditioning training can elicit improvements in corticospinal excitability after ACL reconstruction; however, improvements in quadriceps strength and voluntary activation seem not to be attributed solely to operant upconditioning training.

CLINICAL RELEVANCE

Operant conditioning is a promising approach to improve corticospinal excitability after ACL reconstruction. However, optimizing the delivery of operant conditioning protocols by potentially increasing the dosage of operant conditioning and intervening earlier after surgery may be needed to translate these changes to improvements in quadriceps function.

Effects of whole-body vibration training as an adjunct to conventional rehabilitation exercise on pain, physical function and disability in knee osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Knee osteoarthritis (KOA) is a prevalent degenerative joint condition that impairs mobility and quality of life. While whole-body vibration training (WBVT) shows promise as an adjunct to conventional KOA rehabilitation, its efficacy remains unclear due to inconsistent clinical evidence.

OBJECTIVE

To elucidate the combined effects of WBVT and rehabilitation exercise on pain, physical function, and disability in KOA management through a systematic review and meta-analysis.

METHODS

A comprehensive search was conducted across eight electronic databases (PubMed, Web of Science, Embase, PEDro, SPORTDiscus, Scopus, ScienceDirect, and China National Knowledge Infrastructure) up to February 2024. Inclusion criteria were (i) randomized controlled trials comparing combined WBVT and rehabilitation exercise versus rehabilitation alone in KOA (ii) reported clinical outcomes (iii) human studies, and (iv) publications in English or Chinese. Trial quality was assessed using the PEDro scale and Cochrane risk-of-bias tool. The meta-analysis employed random-effects models in Review Manager 5.3 to account for heterogeneity, supported by sensitivity analyses for robustness and subgroup analyses on WBVT frequency effects.

RESULTS

Sixteen RCTs comprising 589 participants were included. The systematic review found that WBVT combined with conventional rehabilitation significantly reduced pain and improved physical function in KOA patients. The meta-analysis quantified these effects, showing that WBVT significantly (i) reduced knee pain (MD = -0.43, 95% CI [-0.70, -0.16], p = 0.002), with greater reductions observed from high-frequency WBVT, and (ii) increased isokinetic knee peak torque compared to rehabilitation exercise alone. No significant differences were found in balance, functional mobility, and disability outcomes. Sensitivity analysis of high-quality trials supported these results. However, the heterogeneity among studies and variations in control group interventions warrant cautious interpretation.

CONCLUSION

WBVT seems to be effective in reducing pain and enhancing muscle strength in KOA patients when used in conjunction with conventional rehabilitation. Future high-quality RCTs must standardize WBVT protocols, emphasize long-term follow-up, and refine dosage for clinically meaningful outcomes. Systematic review registration: International prospective register of systematic reviews (PROSPERO CRD42024508386).

Hamstrings and Quadriceps Weaknesses Following Anterior Cruciate Ligament Reconstruction Persist Up to 6 Months After Return-to-Sport: An Angle-specific Strength Analysis

BACKGROUND

Hamstrings and quadriceps strength recovery and restoration of the hamstrings-to-quadriceps ratio (H/Q ratio) is a major concern after anterior cruciate ligament reconstruction (ACLR). Recently, moment-angle profiles and angle-specific H/Q ratios are receiving increasing interest.

PURPOSE

The first objective of this study was to investigate moment-angle profiles and angle-specific H/Q ratio profiles in athletes with ACLR at the time of RTS. The second objective of this study was to assess whether strength asymmetries identified at the time of RTS, persist after six months.

STUDY DESIGN

Case-Control study.

METHODS

Twenty athletes who had undergone ACLR performed isokinetic strength tests for concentric knee flexion and extension (60°/s) at RTS, and three and six months later. Twenty controls were tested once. T-tests were used to compare strength differences between 1) ACLR athletes and controls and 2) the injured and uninjured leg of the ACLR athletes. Finally, to assess strength deficits over time, two-way ANOVAs were used.

RESULTS

Angle-specific analyses and peak moments showed lower hamstrings strength in the injured leg of ACLR athletes compared to their uninjured leg at RTS. Furthermore, angle-specific analyses showed a lower hamstrings strength and H/Q ratio in the injured leg compared to controls at larger knee flexion angles. The latter deficit was not identified with a peak-based analysis. The asymmetries identified at RTS did not change over the six months following RTS.

CONCLUSIONS

Athletes with ACLR show strength deficits and asymmetries that persist even six months after RTS. As some asymmetries may go undetected by peak-based analyses, angle-specific analyses are recommended.

LEVEL OF EVIDENCE

Level 3b.

The Neuroplastic Outcomes from Impaired Sensory Expectations (NOISE) hypothesis: How ACL dysfunction impacts sensory perception and knee stability

BACKGROUND

The anterior cruciate ligament (ACL) is integral to maintaining knee joint stability but is susceptible to rupture during physical activity. Despite surgical restoration of passive or mechanical stability, patients struggle to regain strength and prior level of function. Recent efforts have focused on understanding how ACL-related changes in the nervous system contribute to deficits in sensorimotor control following injury and reconstruction. We hypothesize that these challenges are partially due to an increase in sensorimotor uncertainty, a state that reduces the precision of movement control.

OBJECTIVES

This review proposes the ACL NOISE (Neuroplastic Outcomes from Impaired Sensory Expectations) hypothesis, reframing current literature to provide a case that increased sensory noise following ACL injury and reconstruction disrupts sensory predictions, which are anticipations of immediate sensory outcomes or motor commands. This disruption in sensory predictions may contribute to altered neurophysiology, such as cross-modal brain activity, and other persistent clinical deficits.

DESIGN

Narrative review RESULTS/FINDINGS: Following ACL injury and reconstruction, the knee and nervous system experience various neurophysiological alterations to overcome elevated sensory uncertainty and inaccurate sensory predictions, contributing to persistent motor deficits.

CONCLUSIONS

We provide a theoretical case based on compelling evidence that suggests prolonged impairment after ACL injury may be secondary to uncertainty in knee sensory perception. Future research should consider testing the NOISE hypothesis by creating a paradigm that examines dynamic joint stability in response to unexpected perturbations. This approach would help assess motor coordination errors and drive the development of clinical strategies aimed at reducing sensory uncertainty following ACL reconstruction.

Comparison of Therapeutic Effects of Different Rehabilitation Methods on Patients Undergoing Total Knee Arthroplasty: A Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The rehabilitation methods after total knee arthroplasty (TKA) can affect the recovery of complications and joint function, and the selection and comparison of rehabilitation methods after TKA still need further research.

METHODS

A comprehensive search of five databases and two clinical trial registration platforms was conducted from inception through March 31, 2024, and conducted to identify eligible randomized controlled trials (RCTs). We extracted the required data according to the Cochrane Handbook for Systematic Reviews of Interventions. Finally, 32 trials involving 2292 patients were included, the mean age of the enrolled patients was ~69.10 years, the sex ratio of males was (31.6%), and the longest follow-up time was 2 years. And we have summarized nine rehabilitation intervention measures: conventional physical therapy (CPT), cryotherapy, thermal therapy (TT), acupuncture, hydrotherapy, neuromuscular training (NT), electrotherapy, continuous passive motion (CPM), continuous active motion (CAM). And use the range of motion (ROM), visual analog scale (VAS), Western Ontario and McMaster Universities osteoarthritis index (WOMAC) as the outcome measure to evaluate the effectiveness of various interventions. A Bayesian network meta-analysis (NMA) was carried out for calculating standardized mean difference (SMD) and the surface under cumulative ranking curve (SUCRA) of improvement of knee joint function after TKA by different rehabilitation methods.

RESULT

After treatment, the ROM results showed that cryotherapy, electrotherapy, and NT had better therapeutic effects. Among them, cryotherapy (WMD = 10.3, 95% CI 1.63-18.2) had a significant therapeutic effect. In terms of VAS, NT and TT showed good therapeutic effects. Among them, NT had a more significant therapeutic effect, while CAM had less effect. After treatment, in terms of WOMAC, TT, hydrotherapy, cryotherapy, and NT had better therapeutic effects. TT had the best therapeutic effect, while Hydrotherapy and Cryotherapy also had certain advantages.

CONCLUSION

NT, TT, cryotherapy, hydrotherapy, and electrotherapy rehabilitation therapies have good therapeutic effects for TKA patients compared with other interventions. Among them, NT may be the best postoperative rehabilitation therapy.

The Effects of Verbal Cues on Electromyographic Activity During a Quadriceps Setting Exercise

CONTEXT

A quadriceps setting exercise is commonly used following knee injury, but there is great variation in cues that clinicians provide to patients when performing the exercise.

OBJECTIVES

To determine if internal, external, or visual cues result in the greatest quadriceps electromyographical (EMG) activity during a quadriceps setting exercise in healthy individuals.

DESIGN

Descriptive laboratory study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty healthy individuals volunteered for this study. Participants were given 1 of 5 cues in a randomized order: internal cue "tighten your thigh muscles," internal cue "push your knee down," external cue "push into the bolster," external cue "push into the strap," or visual biofeedback using the cue "raise the value on the screen as high as you can."

MAIN OUTCOME MEASURE(S)

Normalized vastus lateralis electromyographical activity.

RESULTS

Both visual biofeedback (83.2% ± 24.9%) and the press into the strap condition (76.8% ± 24.4%) produced significantly greater (P < .001) electromyographical activity than the push knee down (53.2% ± 27.0%), tighten thigh (52.7% ± 27.3%), or push into the bolster (50.8% ± 26.3%) conditions. There was no significant difference (P = .10) between the visual biofeedback and press into the strap conditions as well as no significant difference (P > .38) between the push knee down, tighten thigh, or push into the bolster conditions.

CONCLUSION

If the clinical aim during a quadriceps setting exercise is to obtain the greatest volitional muscle recruitment, the use of visual biofeedback or pressing into a strap is recommended.

Strength Setbacks: The Impact of Youth Sport-Related Knee Joint Injuries on Thigh Muscle Strength. A 24-Month Prospective Cohort Study

OBJECTIVE: To compare injured and uninjured limb knee extensor and flexor peak torque between youth who experienced a sport-related, traumatic knee joint injury and comparable uninjured youth, at baseline (≤4 months of injury) and semiannually for 2 years. Differences by injury type and sex were also explored. DESIGN: Prospective cohort study. METHODS: Bilateral knee extensor and flexor concentric isokinetic peak torque at 90° per second was assessed semiannually in 186 youth (106 injured, 80 controls) for 2 years. Between-group differences in strength over time were estimated with generalized estimating equations (95% confidence interval [CI]). Confounding was controlled using inverse probability weighting. Strength differences between those with anterior cruciate ligament (ACL) tears and those with non-ACL tear injuries as well as between male and female participants were explored. RESULTS: Compared to uninjured controls, injured limb knee extensor strength was lowest at baseline (-37.1 Nm; 95% CI, -45.3 to -28.9) and 6-month follow-up (-13.3 Nm; 95% CI, -20.4 to -6.2), with minimal strength gain beyond the 12-month follow-up (1.7 Nm; 95% CI, -14.3 to 17.6). Knee flexor strength of the injured limb was lowest at baseline (-24.6 Nm; 95% CI, -31.5 to -17.8), and there was minimal strength gain beyond 6 months (2.3 Nm; 95% CI, -7.7 to 12.3). The average residual deficit was similar to the knee extensors (10% to 11%) at 24 months. Exploratory analysis suggested no difference based on injury type or sex. CONCLUSION: Injured limb knee extensor and flexor weakness was present after different youth sport-related knee joint injuries. Strength deficits peaked early after injury, improved over time, and plateaued after 12 months, with lingering deficits at 24 months. Thigh muscle strength trajectory was similar across injury types and sex. J Orthop Sports Phys Ther 2025;55(2):1-11. Epub 20 December 2024. doi:10.2519/jospt.2024.12663.

Impact of Resistance Exercise and Nitrate Supplementation on Muscle Function and Clinical Outcomes After Knee Osteoarthritis Surgery in Middle-Aged Women with Sarcopenia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Background/Objectives: Sarcopenia, characterized by reduced muscle mass and strength, is associated with osteoarthritis (OA), particularly in middle-aged women, and may worsen postoperatively. Resistance exercise (RE) can resolve sarcopenia; however, recovery is often suboptimal. Nitrate (NO3-) supplementation may enhance muscle recovery and complement RE. We investigated whether NO3- supplementation combined with RE improves thigh muscle mass and strength in middle-aged women during postoperative rehabilitation. Methods: We conducted a prospective randomized placebo-controlled double-blind study including 36 middle-aged women with sarcopenia and cartilage defects undergoing mesenchymal stem cell implantation. Participants were assigned to RE with NO3- supplementation (NG, n = 18) or with placebo (PG, n = 18) groups. Both groups underwent 12 weeks of supervised RE. The primary outcomes were thigh muscle cross-sectional area (CSA) and knee strength, whereas functional and clinical measures, including the Short Physical Performance Battery (SPPB), skeletal muscle index (SMI), International Knee Documentation Committee (IKDC), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, were secondary outcomes. Results: Thigh muscle CSA decreased in the PG but was maintained in the NG. Knee extension strength improved significantly in the NG compared with that in the PG at 6 and 12 weeks. Knee flexion strength also improved rapidly in the NG, with a significant increase at 6 weeks. SPPB and IKDC scores improved significantly in the NG. However, similar improvements were observed for WOMAC scores in both groups. Conclusions: NO3- supplementation combined with RE effectively prevented muscle atrophy and enhanced muscle strength in our study participants, indicating potential for improving postoperative recovery.

Comparison of Maximum Isometric Strength of the Hip Joint Abductor and Knee Joint Extensor Muscles between Knee Osteoarthritis Patients with and without Self-reported Instability

Patients with knee osteoarthritis (KOA) often have impaired muscle function of the weight-bearing muscles, particularly in the knee and hip joints. This can lead to a significant loss of strength and power and may play a role in the perceived instability of the knee joint. The purpose of this study was to compare the maximum isometric strength of the hip abductor and knee extensor muscles between patients with KOA with and without perceived instability.Nineteen patients with KOA participated in this cross-sectional study and were divided into two groups. The first group (n = 10; women = 4, men = 6, mean age = 67.4 ± standard deviation [SD] 6.4 years) consisted of patients with self-reported instability in the knee joint, and the second group (n = 9; women = 5, men = 4, mean age = 69.6 ± SD 6.7 years) consisted of patients without self-reported instability. Functional and activity limitations were quantified using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Maximum isometric strength of the hip abductors and knee extensors was measured using a belt-mounted handheld dynamometer and expressed as torque (Newton meters [Nm]) by multiplication with the determined lever arm. Torque was normalized to body weight and height.Patients with instability (median WOMAC score = 68) achieved a significantly lower mean torque in hip abduction than the patients without instability (median WOMAC score = 39) (p = 0.01; Cohen's d = 1.31). There was no significant difference in knee extension torque between the groups (p = 0.202; Cohen's d = 0.58).KOA patients with instability were able to develop significantly lower hip abductor strength than those without instability, suggesting that targeted strength training of this muscle group may be important for this group of patients.

The effect of neuromuscular electrical stimulation superimposed on quadriceps training on gait dynamics after anterior cruciate ligament reconstruction

BACKGROUND

Abnormal gait dynamics are an important risk factor responsible for the high incidence of traumatic knee osteoarthritis in patients undergoing anterior cruciate ligament (ACL) reconstruction.

OBJECTIVE

To evaluate the effect of neuromuscular electrical stimulation (NMES) superimposed quadriceps training on gait dynamics.

METHODS

A total of 32 postoperative patients were randomly allocated to the NMES and conventional training (CT) groups, with 16 patients per group. Patients in the CT group received the standardized conventional training for 60 min per day, 3 days per week for 6 weeks, while those in the NMES group received the same conventional training, but with NMES superimposed on the conventional open chain training of the quadriceps. The amount of time for training was equal between the two groups. Patients were evaluated at 8 and 14 weeks after surgery. The outcome measurements were maximum voluntary isometric contraction (MVIC) of the quadriceps used to assess the quadriceps strength, Lysholm score used to assess knee function and peak vertical ground reaction force (PvGRF), heel medial (HM) peak pressure and heel lateral (HL) peak pressure used to assess gait dynamics.

RESULTS

Compared to the CT group, the NMES group had greater improvements in quadriceps strength (p<0.001, effect size = 2.93), knee function (p = 0.049, effect size = 2.06), and gait loading (including HL peak pressure (P = 0.007, effect size = 0.89) and PvGRF (P = 0.019, effect size = 0.62)). After the intervention, participants in both groups had a significantly lower rearfoot impulse and significantly higher forefoot impulse.

CONCLUSIONS

The NMES superimposed on conventional quadriceps open chain training has shown additional improvements in gait loading in patients after ACL reconstruction, which suggests it may contribute to delaying the onset of early postoperative traumatic knee osteoarthritis. In addition, changes in foot impulse may suggest a progressive trend in quadriceps avoidance gait in the early postoperative period.

Prediction of 12-Month Clinical Outcomes Postsurgery Based on 3-Month Knee Examination After Primary Anterior Cruciate Ligament Reconstruction

CONTEXT

Active management of modifiable factors during the early rehabilitation stage can help patients who have undergone anterior cruciate ligament (ACL) reconstruction successfully return to sports. This study aimed to determine predictors for performance on the single-leg hop test and Tegner activity score 12-month post-ACL reconstruction, based on knee function assessed 3-month postsurgery.

DESIGN

Prospective cohort study.

METHODS

Ninety-one patients who underwent ACL reconstruction were recruited. Multivariate logistic regression analysis was performed to identify predictors of the one hop test and Tegner activity score 12-month postsurgery, based on a knee examination performed 3 months after ACL reconstruction. Factors evaluated at 3 months included the Biodex balance system anteroposterior and mediolateral indexes; Y balance test anterior, posteromedial, and posterolateral reaches; knee extensors and flexors peak torque per body weight; and knee extensors and flexors average power per body weight.

RESULTS

The knee extensor peak torque per body weight (PT/BW) and Biodex balance system-mediolateral index with cutoff values of 132 N·m/kg and 0.45, respectively were identified as predictors for achieving a limb symmetric index within 10% on the hop test. Furthermore, achieving a Tegner activity score over 6 was predicted by Y balance test-posteromedial reach and knee flexors average power per body weight, with cutoff values of 92.5 cm and 122 W/kg, respectively.

CONCLUSION

Three months following ACL reconstruction, knee extensor peak torque, and mediolateral balance predicted performance on the hop test, while dynamic posteromedial balance and knee flexors average power predicted rotational ability, at the 12-month assessment.

The Effect of Physiotherapy on Arthrogenic Muscle Inhibition After ACL Injury or Reconstruction: A Systematic Review

Arthrogenic muscle inhibition (AMI) following ACL injury or reconstruction is a common issue that affects muscle activation and functional recovery. Thus, the objective of this study was to systematize the literature on the effects of physiotherapy interventions in the rehabilitation of AMI after ACL injury or reconstruction. A systematic review was conducted following the PRISMA guidelines. The risk of bias was evaluated using the PEDro scale and the Cochrane risk of bias tool. Searches were performed in the PubMed, Google Scholar, Cochrane Library, and EMBASE databases. Randomized controlled trials involving patients with ACL injuries or ACL reconstruction were included. Twenty studies were included. Fifteen evaluated the effects of exercise, showing significant improvement. Seven studies examined electrotherapy, with neuromuscular electrical stimulation and high-frequency therapy combined with exercise showing improvements in muscle strength, pain, and joint range of motion. Nine studies explored interventions like motor imagery, cryotherapy, taping, and vibration. When performed before exercise, motor imagery and cryotherapy improved cortical activity and muscle recovery. Kinesio taping reduced edema and pain better than exercise alone. Vibration showed inconsistent results across three studies. Methodological quality varied between 5 and 8 on the PEDro scale, with moderate-to-low risk of bias. Structured exercise should be the first-line intervention, but combining it with other therapies enhances rehabilitation. The study protocol was registered in the PROSPERO database (CRD42023425510).

Treatment of Arthrogenic-Muscle-Inhibition in patients after knee-surgery with Motion-Activated-Neuromuscular stimulation - a case-series

Arthrogenic muscle inhibition (AMI) presents a persistent challenge in postoperative knee rehabilitation and is often resistant to standard care. This case series examines the efficacy of Motion-Activated Neuromuscular Electrical Stimulation (mNMES) in addressing AMI refractory to rehabilitation after ACL (revision) surgery, patellar dislocation, trochleoplasty, or conservative treatment of the patellofemoral pain syndrome. Eight patients who had undergone extensive unsuccessful rehabilitation received six weeks of a novel mNMES treatment regimen. Outcome assessments included patient-reported outcome measures (PROMs) and AMI classification. Results revealed significant improvements in pain reduction, knee function, and AMI reduction. Despite study limitations, mNMES demonstrated promising outcomes and could be used as an adjunct to standard rehabilitation, offering potential for enhancing postoperative outcomes in patients refractory to conventional therapy. Further research is required to validate these findings and optimise treatment protocols.

Comparative transcriptomic analysis revealed potential mechanisms regulating the hypertrophy of goose pectoral muscles

Pectoral muscle development is an important economic trait. According to the different essence, muscle development can be divided into 2 processes: embryonic muscle fiber generation and postnatal muscle fiber hypertrophy, and postnatal muscle fiber hypertrophy has a greater impact on muscle development than the number of muscle fibers formed during the embryonic phase in poultry. However, the underlying mechanisms regulating the hypertrophy of goose pectoral muscles have not been elucidated. Therefore, the purpose of the present study was to conduct transcriptome sequencing in pectoral muscles of both Landes (LD) and Sichuan White (SW) geese at 6, 10, and 30 weeks of age to reveal the molecular mechanisms regulating pectoral muscle hypertrophy through intra-breed and inter-breed bioinformatics analyses. Phenotypically, the pectoral muscle weight/index of LD and SW geese increased from 6 to 30 weeks of age, and except for the pectoral muscle index at 10 weeks of age (P = 0.962), at the same age, the pectoral muscle weight/index of LD geese were significantly higher than that of SW geese (P < 0.05). In transcriptional regulation, intra-breed bioinformatics analysis identified 3331 genes whose expression levels were opposite to the trend of pectoral muscle hypertrophy both in LD and SW geese, and the 3331 genes were mainly enriched into abundant KEGG pathways related to lipid metabolism, proliferation/apoptosis, and immune response. Moreover, 23 genes (including SLC2A10, TNFRSF1A, PRKAA1, SLC27A4, ITGB2, THY1, RHOA, MYL10, ACTB, PRKCB, PIK3R2, RAC2, DMD, LATS2, YAP1, WWTR1, SMAD7, CTGF, FGF1, AXIN2, GLI2, ID2, and CCND2) who were enriched in 6 crosstalk pathways named viral myocarditis, insulin resistance, sphingolipid signaling pathway, hippo signaling pathway, chemokine signaling pathway, and leukocyte transendothelial migration were identified as the key candidate genes regulating the hypertrophy of goose pectoral muscles. In inter-breed bioinformatics analysis, abundant different expression genes (DEGs) related to lipid metabolism, immune response, and proliferation/apoptosis were identified between LD and SW geese too, and compared with SW geese, the expression level of MYL10 in LD geese was lower, while the expression levels of GLI2/CTGF/SMAD7 in LD geese were higher. These results suggested that the hypertrophy of goose pectoral muscles might be achieved through more lipid deposition and less leukocyte infiltration to promote the proliferation of cells within the muscles, and the low expression of MYL10 and high expressions of GLI2/CTGF/SMAD7 might the keys to induce the pectoral muscle hypertrophy of LD geese from 6 to 30 weeks of age over that of SW geese. All data the present study obtained will provide new insights into the molecular mechanisms regulating the hypertrophy of goose pectoral muscles.

Clinical benefit of physical rehabilitation after total hip and knee arthroplasty: A pragmatic, randomized, controlled trial (The DRAW1 trial)

Importance

Comparative effectiveness trials have not shown superiority of one type of physical rehabilitation over another following total hip (THA) and knee (TKA) arthroplasty. We therefore ask the fundamental effectiveness question: Does physical rehabilitation "work" better than no physical rehabilitation?

Objective

To compare the effectiveness of a 6-week program of physical rehabilitation (home-based telerehabilitation, or home-based rehabilitation) to no physical rehabilitation following THA and TKA.

Design

3-arm,randomized, controlled, superiority trial with blinded outcome assessments. 377 patients (210 THA/167 TKA) were screened for eligibility before the targeted sample size of 168 patients was reached. Outcome measures were assessed at baseline, at the end of intervention (6 weeks), and 3 and 12 months postoperatively. The primary outcome was the Hip disability and Osteoarthritis Outcome Score (HOOS)/Knee injury and Osteoarthritis Outcome Score (KOOS)-subscale: function in daily living. Secondary outcomes included: HOOS/KOOS-subscales: pain, symptoms, and quality of life, patient global assessment, analgesics, walking aids, 30-s chair stand test, 4 ​× ​10 ​m fast-paced walk test, exercise adherence, and satisfaction.

Results

Comparing physical rehabilitation (home-based telerehabilitation, and home-based rehabilitation) to no physical rehabilitation, the mean group-differences for the primary outcome were 3.3 (95%CI: -1.9 to 8.6; p ​= ​0.10) points at 6 weeks, and 1.9 (95%CI: -3.7 to 7.6; p ​= ​0.25) and 2.6 (95%CI: -4.4 to 9.6; p ​= ​0.23) points at the 3- and 12-months follow-ups, respectively.

Conclusion

Physical rehabilitation was not superior to the no physical rehabilitation comparator following THA or TKA in terms of self-reported function or any of the secondary outcomes.

Trial registration

NCT03750448 (November 23, 2018), URL: https://clinicaltrials.gov/ct2/show/NCT03750448.

Oh, My Quad: A Clinical Commentary And Evidence-Based Framework for the Rehabilitation of Quadriceps Size and Strength after Anterior Cruciate Ligament Reconstruction

Quadriceps weakness after anterior cruciate ligament reconstruction (ACLR) is a well-known phenomenon, with more persistent quadriceps weakness observed after ACLR with a bone-patellar tendon-bone or quadriceps tendon autograft than with a hamstring tendon autograft. Longstanding quadriceps weakness after ACLR has been associated with suboptimal postoperative outcomes and the progression of radiographic knee osteoarthritis, making the recovery of quadriceps size and strength a key component of ACLR rehabilitation. However, few articles have been written for the specific purpose of optimizing quadriceps size and strength after ACLR. Therefore, the purpose of this review article is to integrate the existing quadriceps muscle basic science and strength training literature into a best-evidence synthesis of exercise methodologies for restoring quadriceps size and strength after ACLR, as well as outline an evidence-informed quadriceps load-progression for recovering the knee's capacity to manage the force-profiles associated with high-demand physical activity. Level of Evidence: 5.

Associations between biomarkers and skeletal muscle function in individuals with osteoarthritis: a systematic review and meta-analysis

OBJECTIVES

Skeletal muscle dysfunction is the primary cause of functional limitations in osteoarthritis, associated biomarkers have the potential as targets for early disease identification, diagnosis, and prevention of osteoarthritis disability. This review aimed to identify associations between biomarkers and lower limb skeletal muscle function in individuals with osteoarthritis.

METHODS

A systematic literature review and meta-analysis conducted in PubMed, MEDLINE, CINAHL, EMBASE, Scopus, SPORTDiscus and Web of Science databases from inception to 8th August 2023. Two independent reviewers performed the title, abstract, full-text screening, data extraction and methodological quality assessment. A meta-analysis was undertaken based on the available data.

RESULTS

Twenty-four studies with 4101 participants with osteoarthritis were included (females: 78%; age range; 49 to 71 years). One study reported muscle-specific biomarkers (n = 3), whilst six studies reported osteoarthritis-specific markers (n = 5). Overall, 93 biomarkers were reported, predominately characterised as inflammatory (n = 35), metabolic (n = 15), and hormones (n = 10). Muscle strength and vitamin D reported a significant association (Hedge's g: 0.58 (Standard Error (SE): 0.27; P = 0.03), k = 3 studies). Walking speed and high-sensitivity C-reactive protein reported no significant associations (Hedge's g: -0.02 (SE: 0.05; P = 0.73), k = 3 studies).

CONCLUSION

Associations between biomarkers and lower limb skeletal muscle function in individuals with osteoarthritis was limited, the few studies exploring lower limb muscle measures were mainly secondary outcomes. Furthermore, biomarkers were largely related to overall health, with a lack of muscle specific biomarkers. As such, the mechanistic pathways through which these associations occur are less evident, and difficult to draw clear conclusions on these relationships.

TRIAL REGISTRATION

Registered on PROSPERO (CRD42022359405).

A network pharmacology-based study to investigate the mechanism of curcumin-regulated regenerative repair of quadriceps femoris muscle in KOA rats

BACKGROUND

Knee osteoarthritis (KOA) is a very common musculoskeletal disorder, and patients with KOA often exhibit significant quadriceps femoris muscle atrophy. It is well established that curcumin (CUR) exerts protective effects on skeletal muscle. However, the efficacy of CUR in treating KOA-induced quadriceps femoris muscle atrophy and its underlying mechanisms remain uncertain. In this study, we employed network pharmacology to investigate the mechanism by which CUR promotes regenerative repair of the quadriceps femoris muscle in rats with KOA.

METHODS

The potential targets of CUR were obtained from Swiss Target Prediction. The targets of skeletal muscle regeneration were identified from GeneCard and OMIM. A Venn diagram was generated to visualize the intersection of CUR targets and skeletal muscle regeneration targets, and the core targets were identified using STRING. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted using DAVID. Finally, the network pharmacology results were further validated by establishing a KOA rat model using the Hulth method.

RESULTS

Network pharmacology analysis and molecular docking results revealed that CUR affects skeletal muscle regeneration through multiple targets and pathways. In vivo experimental results were validated by demonstrating that KOA causes atrophy and induces apoptosis in the quadriceps femoris muscle. Furthermore, CUR was shown to inhibit apoptosis in the quadriceps femoris muscle by regulating STAT3 and FOS, as well as the PI3K/AKT signaling pathway.

CONCLUSIONS

Our study revealed the apoptosis-inhibiting effects of CUR and its underlying mechanisms. Consequently, CUR has the potential to improve quadriceps femoris muscle atrophy caused by KOA.

[Blood flow restriction training (BFRT) in patients before and after total knee arthroplasty]

BACKGROUND

In healthy individuals, blood flow restriction training (BFRT) has shown positive effects on muscle mass, strength, fatigue resistance, as well as tendon and bone metabolism. BFRT reduces blood flow in the extremities using inflatable cuffs, creating local muscular hypoxia, which produces an anabolic metabolic environment. This promotes significant muscular and cardiovascular adaptations even at low mechanical training loads.

KNEE ENDOPROSTHESES

BFRT also shows promising initial results in pre- and postoperative applications for knee endoprostheses (KTEP). Both preoperative and postoperative BFRT can improve muscle strength and joint function, accelerate recovery, and alleviate pain. Although the method is generally safe, potential risks such as discomfort and rare side effects must be considered. Clear application protocols are still lacking, necessitating further research and individualized programs to achieve optimal training effects. BFRT thus offers an innovative way to effectively rehabilitate patients despite their low load tolerance.

Optimizing the Preoperative Preparation of Sarcopenic Older People: The Role of Prehabilitation and Nutritional Supplementation before Knee Arthroplasty

BACKGROUND

Age-related loss of skeletal muscle strength and mass is linked to adverse postoperative outcomes in older individuals with sarcopenia. Half of patients suffer from severe associated osteoarthritis requiring orthopedic interventions. Mitigating the onset and progression of sarcopenia before surgery is essential to improve the prognosis and reduce surgical complications. The aim of this research was to innovatively explore whether the preoperative period could be the appropriate timeframe to empower surgical resilience, through prehabilitation and dietary supplementation, in older sarcopenic patients undergoing knee arthroplasty.

METHODS

The current literature concerning the effectiveness of prehabilitation and dietary supplementation before knee arthroplasty in sarcopenic older individuals was reviewed, following the SANRA criteria, between December 2023 and February 2024. The study inclusion criteria were as follows: (1) prehabilitation and/or dietary supplementation interventions; (2) human participants aged 65 years and older; (3) relevant outcome reporting (functional status, postoperative complications, and patient-reported outcomes); and (4) articles written in English The extracted information included study characteristics, demographics, intervention details, outcomes, and the main findings.

RESULTS

Merged prehabilitation and dietary supplementation strategies extrapolated from the current literature and involving strength, resistance, balance, and flexibility training, as well as essential amino acids, iron, vitamin D, adenosine triphosphate, and glucosamine sulphate supplementation, could improve the functional capacity, ability to withstand the upcoming surgical stressors, and postoperative outcomes in older people undergoing knee arthroplasty.

CONCLUSIONS

Addressing complex links between knee osteoarthritis and sarcopenia in older individuals undergoing knee arthroplasty requires a multidimensional approach. Prehabilitation emerges as a crucial preliminary step, allowing the optimization of surgical outcomes. Nutraceutical integration, included in a comprehensive care plan, could have a synergic effect in achieving prehabilitation goals. Those interventions are essential for surgical resilience, in terms of muscle function preservation, recovery acceleration, and overall quality of life enhancement. Intensive collaboration among specialists could advance knowledge and the sharable consensus concerning the critical and evolutive field of perioperative care.

The future of in-field sports biomechanics: wearables plus modelling compute real-time in vivo tissue loading to prevent and repair musculoskeletal injuries

This paper explores the use of biomechanics in identifying the mechanistic causes of musculoskeletal tissue injury and degeneration. It appraises how biomechanics has been used to develop training programmes aiming to maintain or recover tissue health. Tissue health depends on the functional mechanical environment experienced by tissues during daily and rehabilitation activities. These environments are the result of the interactions between tissue motion, loading, biology, and morphology. Maintaining health of and/or repairing musculoskeletal tissues requires targeting the "ideal" in vivo tissue mechanics (i.e., loading and deformation), which may be enabled by appropriate real-time biofeedback. Recent research shows that biofeedback technologies may increase their quality and effectiveness by integrating a personalised neuromusculoskeletal modelling driven by real-time motion capture and medical imaging. Model personalisation is crucial in obtaining physically and physiologically valid predictions of tissue biomechanics. Model real-time execution is crucial and achieved by code optimisation and artificial intelligence methods. Furthermore, recent work has also shown that laboratory-based motion capture biomechanical measurements and modelling can be performed outside the laboratory with wearable sensors and artificial intelligence. The next stage is to combine these technologies into well-designed easy to use products to guide training to maintain or recover tissue health in the real-world.

Lower Extremity Muscle Volume in Unilateral and Bilateral Patellofemoral Pain: A Cross-Sectional Exploratory Study Including Superficial and Deep Muscles

CONTEXT

Existing patellofemoral pain (PFP) literature has primarily been focused on quadriceps muscle volume, with limited attention given to the deep and superficial muscle volume of the lower limbs in individuals with unilateral and bilateral PFP. In this paper, we aim to fill this gap.

OBJECTIVE

To explore superficial and deep lower extremity muscle volume in women with unilateral or bilateral PFP compared with a normative database of pain-free women.

DESIGN

Cross-sectional study.

SETTING

University imaging research center.

PATIENTS OR OTHER PARTICIPANTS

Twenty women with PFP (10 unilateral and 10 bilateral) and 8 pain-free women from a normative database.

MAIN OUTCOME MEASURE(S)

We quantified lower extremity muscle volume via 3.0-T magnetic resonance imaging. Two separate 1-way analyses of variance were performed: (1) unilateral PFP (painful versus nonpainful limb) versus pain-free control groups and (2) bilateral PFP (more painful versus less painful limb) versus pain-free control groups.

RESULTS

We observed no differences in age and body mass index across groups (P > .05). Compared with the pain-free group, the unilateral and bilateral PFP groups had bilaterally smaller volumes of the anterior (iliacus: P ≤ .0004; d range, 2.12-2.65), medial (adductor brevis, adductor longus, gracilis, and pectineus: P ≤ .02; d range, 1.25-2.48), posterior (obturator externus, obturator internus, and quadratus femoris: P < .05; d range, 1.17-4.82), and lateral (gluteus minimus: P ≤ .03; d range, 1.16-2.09) hip muscles and knee extensors (rectus femoris: P ≤ .003; d range, 1.67-2.16) and flexors (long and short head of the biceps femoris: P ≤ .01, d range, 1.56-1.93).

CONCLUSIONS

Women with unilateral and those with bilateral PFP displayed less volume of multiple superficial and deep muscles of the bilateral hips and knees than pain-free women. Interventions should bilaterally target lower limb muscles when treating PFP, and hypertrophy exercises for specific muscles should be explored to increase choices for intervention.

Low-frequency sounds combined with motor imagery elicits a transient disruption of force performance: A path to neuromotor reprogramming?

The effectiveness of motor imagery (MI) training on sports performance is now well-documented. Recently, it has been proposed that a single session of MI combined with low frequency sound (LFS) might enhance muscle activation. However, the neural mechanisms underlying this effect remain unknown. We set up a test-retest intervention over the course of 2 consecutive days to evaluate the effect of (i) MI training (MI, n = 20), (ii) MI combined with LFS (MI + LFS, n = 20), and (iii) a control condition (CTRL, n = 20) on force torque produced across repeated maximal voluntary contractions of the quadriceps before (Pretest), after (Posttest) and at +12 h (Retention) post-intervention. We collected the integrated electromyograms of the quadriceps muscles, as well as brain electrical potentials during each experimental intervention. In the CTRL group, total force torque decreased from Pretest to Retention and from Posttest to Retention. By contrast, there was an increase between Posttest and Retention in both MI + LFS and MI groups (both ηP2 = 0.03, p < 0.05). Regression analyses further revealed a negative relationship between force performance and EEG activity in the MI + LFS group only. The data support a transient interference of LFS on cortical activity underlying the priming effects of MI practice on force performance. Findings are discussed in relation to the potential for motor reprogramming through MI combined with LFS.

Assessment of arthrogenic quadriceps muscle inhibition by physical examination in the supine position during isometric contraction is feasible as demonstrated by electromyography: a cross-sectional study

BACKGROUND

Preventing severe arthrogenic muscle inhibition (AMI) after knee injury is critical for better prognosis. The novel Sonnery-Cottet classification of AMI enables the evaluation of AMI severity but requires validation. This study aimed to investigate the electromyography (EMG) patterns of leg muscles in the examination position from the classification during isometric contraction to confirm its validity. We hypothesised that the AMI pattern, which is characterised by quadriceps inhibition and hamstring hypercontraction, would be detectable in the supine position during isometric contraction.

METHODS

Patients with meniscal or knee ligament injuries were enrolled between August 2023 and May 2024. Surface EMG was assessed during submaximal voluntary isometric contractions (sMVIC) at 0° extension in the supine position for the vastus medialis (VM) and vastus lateralis (VL) muscles and at 20° flexion in the prone position for the semitendinosus (ST) and biceps femoris (BF) muscles. Reference values for normalisation were obtained from the EMG activity during the gait of the uninjured leg. The Kruskal-Wallis test was used to compare the activation patterns of the muscle groups within the same leg, and the post-hoc tests were conducted using the Mann-Whitney U test and Bonferroni correction.

RESULTS

Electromyographic data of 40 patients with knee injuries were analyzed. During sMVIC, the extensor and flexor muscles of the injured leg showed distinct behaviours (P < 0.001), whereas the uninjured side did not (P = 0.144). In the injured leg, the VM differed significantly from the ST (P = 0.018), and the VL differed significantly from the ST and BF (P = 0.001 and P = 0.026, respectively). However, there were no statistically significant differences within the extensor muscle groups (VM and VL, P = 0.487) or flexor muscle groups (ST and BF, P = 0.377).

CONCLUSION

AMI was detectable in the examination position suggested by the Sonnery-Cottet classification. The flexor and extensor muscles of the injured leg exhibited distinct activation behaviours, with inhibition predominantly occurring in the quadriceps muscles, whereas the hamstrings showed excitation.

Abnormality in re-programing of preparatory muscle activity for landing following unpredictable events in patients with anterior cruciate ligament injury

BACKGROUND

Anterior cruciate ligament deficiency (ACL-D) causes dysfunction in the quadriceps femoris muscle, and this dysfunction hampers a safe return to sports. However, how the dysfunctional quadriceps femoris muscle affects instantaneous re-programming of motor command in response to unpredictable events remains unknown. This study aimed to examine the effects of ACL-D on re-programming of preparatory muscle activity during an unpredictable landing task.

METHODS

Eighteen patients with ACL-D and 20 healthy participants (controls) performed normal landing and surprise landing tasks. In the surprise landing task, a false floor, designed to dislodge easily under load, was positioned in the middle of the descent path. This setup causes participants to unpredictably fall through the false floor onto the actual landing surface. Electromyography data collected during the period after passing through the false floor until landing was segmented into two equal halves. The average electromyography amplitude for each muscle in each period was compared between patients and controls.

RESULTS

In the vastus medialis and rectus femoris during the surprise landing task, the average electromyography amplitude during only the second half period in patients with ACL-D was significantly smaller than that in controls (p = 0.011 and 0.004, respectively).

CONCLUSIONS

Abnormalities were detected in the re-programming of preparatory muscle activation during an unpredictable landing task in the vastus medialis and rectus femoris of patients with ACL-D. The surprise landing task used in the present study has the potential to become a diagnostic tool to evaluate readiness for safely returning to sports.

The Effectiveness of a Single Hyaluronic Acid Injection in Improving Symptoms and Muscular Strength in Patients with Knee Osteoarthritis: A Multicenter, Retrospective Study

Knee osteoarthritis (KOA) is a progressive and multifactorial disease that leads to joint pain, muscle weakness, physical disability, and decreased quality of life. In KOA, the quantity of hyaluronic acid (HA) and the molecular weight (MW) are decreased, leading to joint pain due to increased wear of the knee articular cartilage. Arthrogenic muscle inhibition, which is usually found in patients with KOA, is associated with joint inflammation, pain, and swelling, also causing muscle atrophy, primarily of the anterior thigh muscles, and hindering the rehabilitation process. The aim of our work was to determine if a single HA infiltration could minimize the effects of arthrogenic muscle inhibition in patients with KOA in the short term, using isokinetic dynamometry to evaluate the strength of the knee extensor and flexor muscles of the thigh. Thirty patients with KOA who underwent both clinical and isokinetic assessment, and that received a single injection of HA, were retrospectively included. Our results showed that a single intra-articular injection of HA significantly reduces pain and improves joint function at four weeks, while non-statistically significant improvements were observed for the reference isokinetic parameter (maximum torque) at both 90°/s and 180°/s. Further high-quality studies are necessary to confirm the results of our study.

Ultrasound-guided gluteal nerves electrical stimulation to enhance strength and power in individuals with chronic knee pain: a randomized controlled pilot trial

Introduction

Various pathophysiological contexts can be accompanied by weakness, arthrogenic muscle inhibition, and even disability. In this scenario, peripheral nerve stimulation has been studied not only for pain management but also for the improvement of neuromuscular parameters. For this purpose, the use of Transcutaneous Electrical Nerve Stimulation (TENS) has typically been investigated, but recently, the use of ultrasound-guided percutaneous peripheral nerve stimulation (pPNS) has gained popularity. In this regard, electrical stimulation has a predisposition to activate Type II muscle fibers and has been shown to be capable of generating short-term potentiation by increasing calcium sensitivity. However, the evidence of pPNS applied in humans investigating such variables is rather limited.

Objectives

This pilot study aimed to assess the feasibility of the methodology and explore the potential of pPNS in enhancing hip extension performance in individuals suffering from knee pain, comparing it with TENS.

Methods

Twelve participants were divided into pPNS and TENS groups, undergoing pre- and post-intervention assessments of peak concentric power (W), strength (N), execution speed (m/s), and one-repetition maximum (1RM) (kg) estimation. For pPNS, two needles were positioned adjacent to the superior and inferior gluteal nerves under ultrasound guidance. For TENS, electrodes were positioned between the posterosuperior iliac spine and the ischial tuberosity, and halfway between the posterosuperior iliac spine and the greater trochanter. The interventions consisted of 10 stimulations of 10 s at a frequency of 10 Hz with a pulse width of 240 μs, with rest intervals of 10 s between stimulations.

Results

Peripheral nerve stimulation significantly improved concentric power at 30% (p = 0.03) and 50% (p = 0.03) of 1RM, surpassing TENS, which showed minimal changes. No significant strength differences were observed post-intervention in either group.

Conclusion

This work presents evidence where pPNS applied to the gluteal nerves results in an enhanced performance of hip extension at submaximal loads. However, this improvement does not seem to be reflected in short-term changes in the estimation of the 1RM by the force-velocity profile.

Effects of a mat Pilates-based exercise program for low back pain in helicopter pilots of the Brazilian Air Force: Randomized controlled trial

INTRODUCTION

Helicopter pilots may present chronic low back pain due to vibration exposure and asymmetric posture during flight.

OBJECTIVES

To analyze the effects of a Pilates-based exercise program on low back pain of helicopter pilots of the Brazilian Air Force.

METHODS

This is a randomized controlled trial with fifteen helicopter pilots of the Brazilian Air Force, who were assessed for pain intensity (Numerical Pain Rating Scale), disability associated with low back pain, and spine muscle endurance in three positions: trunk extension (Ito test) and left and right lateral bridge. Individuals were randomly distributed into the regular exercises group (REG) (n = 7), oriented to maintain their exercise routine, and Pilates group (PG) (n = 8), which performed an exercise program based on Pilates method twice a week for 12 weeks. Reassessments occurred after 6 and 12 weeks. Data were analyzed on SPSS 20.0 software using a significance level of 5%.

RESULTS

PG showed a significant reduction in low back pain after 12 weeks of training compared with REG (mean difference of 3.5 points, p < 0.0001). We also observed increased endurance of trunk extensors (p = 0.002) and right (p = 0.001) and left lateral muscles (p = 0.001) in the PG compared with REG. However, the indexes of disability did not change between groups.

CONCLUSION

Pain intensity was significantly reduced while spine muscle endurance increased in PG compared with REG after intervention; thus, Pilates-based exercises should be considered in physical conditioning programs for helicopter pilots.

30-sit-to-stand power is a better tool than isometric knee extensor strength to detect motor impairment in people with haemophilic arthropathy

INTRODUCTION

Regular assessment of motor impairments is crucial in people with haemophilic arthropathy (PwHA). This study aimed to determine if there are differences in 30-seconds sit-to-stand (30-STS) power and maximal voluntary isometric contraction (MVIC) of the knee extensors between PwHA and healthy control group (CG). The secondary aims were to investigate the correlation between 30-STS power and MVIC of knee extensors with clinical characteristics and to assess their effectiveness in identifying motor impairment in PwHA.

METHODS

A cross-sectional study was conducted by collecting data from PwHA (n = 17) and a sedentary CG (n = 15). MVIC (torque) and 30-STS power were normalised to body mass. Correlation analysis and simple linear regression adjusted for age were used to assess the association between tests and clinical variables. Using z-scores derived from the mean and standard deviation of the CG, we compared the MVIC and the 30-STS power in PwHA.

RESULTS

PwHA showed lower MVIC and 30-STS power compared to CG (p < .001; large effect size d > .8). Lower 30-STS power was associated with greater joint impairment and greater fear of movement, whereas MVIC showed no association with clinical variables. 30-STS power showed a lower z-score compared to MVIC (p < .001). In addition, 30-STS power detected 47% of PwHA with motor impairment compared to 0% for MVIC (p = .002).

CONCLUSIONS

Our results suggest that 30-STS power may be more effective than knee extensors MVIC in detecting motor impairment in PwHA. Consequently, lower limb skeletal muscle power, rather than maximum knee extensor strength, appears to be more affected in PwHA.

Comparison of Analgesic Effects of Continuous Femoral Nerve Block, Femoral Triangle Block, and Adductor Block After Total Knee Arthroplasty: A Randomized Clinical Trial

OBJECTIVES

This study aimed to compare the analgesic effects of continuous femoral nerve block (FNB), femoral triangle block (FTB), and adductor canal block (ACB) following total knee arthroplasty (TKA). The goal was to identify the most effective nerve block technique among these.

METHODS

Patients undergoing TKA were randomly assigned to 1 of 3 groups: FNB, FTB, or ACB. Nerve blocks were administered preoperatively, with catheters placed for patient-controlled nerve analgesia (PCNA). The primary end point was the Numeric Rating Scale (NRS) score at movement at 24 hours postsurgery. Secondary end points included NRS scores at rest and movement, quadriceps strength, Timed Up and Go (TUG) test performance, range of motion, effective PCNA utilization, and opioid consumption at various postsurgery time points.

RESULTS

Of the 94 valid data sets analyzed (FNB: 31, FTB: 31, ACB: 32), significant differences were observed in the primary end point (H=7.003, P =0.03). Post hoc analysis with Bonferroni correction showed that the FNB group had a significantly lower median pain score (3 [2 to 4]) compared with the ACB group (4 [3 to 5], Bonferroni-adjusted P =0.03). Regarding secondary end points, both the FNB and FTB groups had significantly lower NRS scores than the ACB group at various time points after surgery. Quadriceps strength and TUG completion were better in the FTB and ACB groups. There were no statistically significant differences among the groups for the other end points.

DISCUSSION

Continuous FTB provides postoperative analgesia comparable to FNB but with the advantage of significantly less impact on quadriceps muscle strength, a benefit not seen with FNB. Both FTB and ACB are effective in preserving quadriceps strength postoperatively.

Longitudinal Changes in Quadriceps Morphology over the First 3 Months after Anterior Cruciate Ligament Reconstruction

PURPOSE

Neuromuscular deficits and atrophy after anterior cruciate ligament reconstruction (ACLR) may be accompanied by changes in muscle composition and poor quadriceps muscle quality (QMQ). Quadriceps atrophy occurs after ACLR but improves within the first three postoperative months, yet this hypertrophy could be attributable to increases in noncontractile tissue (i.e., poor QMQ). The purposes of this study were to evaluate changes in QMQ after ACLR and to determine if changes in QMQ and cross-sectional area (CSA) occur in parallel or independently.

METHODS

A longitudinal prospective cohort design was implemented to evaluate QMQ and CSA in 20 individuals with ACLR and 12 healthy controls. Participants completed three testing sessions (baseline/presurgery, 1 month, and 3 months) during which ultrasound images were obtained from the vastus lateralis (VL) and rectus femoris (RF). QMQ was calculated as the echo intensity (EI) of each image, with high EI representing poorer QMQ. Anatomical CSA was also obtained from each image.

RESULTS

RF and VL EI were greater at 1 and 3 months in the ACLR limb compared with baseline and the contralateral limb and did not change between 1 and 3 months. VL and RF CSA in the ACLR limb were smaller at 1 and 3 months compared with the contralateral limb and controls (VL only) but increased from 1 to 3 months. Changes in QMQ and CSA were not correlated.

CONCLUSIONS

QMQ declines within the first month after ACLR and does not improve by 3 months although hypertrophy occurs, suggesting that these morphological characteristics change independently after ACLR. Poorer QMQ represents greater concentration of noncontractile tissues within the muscle and potentially contributes to chronic quadriceps dysfunction observed after ACLR.

Neuromotor Treatment of Arthrogenic Muscle Inhibition After Knee Injury or Surgery

BACKGROUND

Persistent weakness of the quadriceps muscles and extension deficit after knee injuries are due to specific alterations in neural excitability - a process known as arthrogenic muscle inhibition (AMI). The effects of a novel neuromotor reprogramming (NR) treatment based on the use of proprioceptive sensations associated with motor imagery and low frequency sounds have not been studied in AMI after knee injuries.

HYPOTHESIS

This study aimed to assess quadriceps electromyographic (EMG) activity and the effects on extension deficits in persons with AMI who completed 1 session of NR treatment. We hypothesized that the NR session would activate the quadriceps and improve extension deficits.

STUDY DESIGN

Case series.

LEVEL OF EVIDENCE

Level 4.

METHODS

Between May 1, 2021 and February 28, 2022, patients who underwent knee ligament surgery or sustained a knee sprain with a deficit of >30% of the vastus medialis oblique (VMO) on EMG testing in comparison with the contralateral limb after their initial rehabilitation were included in the study. The maximal voluntary isometric contraction of the VMO measured on EMG, the knee extension deficit (distance between the heel and the table during contraction), and the simple knee value (SKV) were assessed before and immediately after completion of 1 session of NR treatment.

RESULTS

A total of 30 patients with a mean age of 34.6 ± 10.1 years (range, 14-50 years) were included in the study. After the NR session, VMO activation increased significantly, with a mean increase of 45% (P < 0.01). Similarly, the knee extension deficit significantly improved from 4.03 ± 0.69 cm before the treatment to 1.93 ± 0.68 after the treatment (P < 0.01). The SKV was 50 ± 5.43% before the treatment, and this increased to 67.5 ± 4.09% after the treatment (P < 0.01).

CONCLUSION

Our study indicates that this innovative NR method can improve VMO activation and extension deficits in patients with AMI. Therefore, this method could be considered a safe and reliable treatment modality in patients with AMI after knee injury or surgery.

CLINICAL RELEVANCE

This multidisciplinary treatment modality for AMI can enhance outcomes through the restoration of quadriceps neuromuscular function and subsequent reduction of extension deficits after knee trauma.

Prolonged Physiotherapy after Anterior Cruciate Ligament Reconstruction Does Not Improve Muscular Strength and Function

Background: After the rupture of the anterior cruciate ligament (ACL), surgery is proposed in the case of knee instability or for athletes who want to return to a pivotal and/or contact sport. The current trend is to extend physiotherapy sessions until a patient's return to sport. We aimed to assess the interest in prolonging the physiotherapy sessions up to 4 postoperative months to restore muscle knee strength and function. Methods: From a historical cohort, 470 patients (24.3 ± 8.7 years) were included; 312 (66%) were males. They all had undergone a primary ACL reconstruction with a hamstring procedure. The number of physiotherapy sessions was established at 4 postoperative months. The main study parameters to assess the benefit of prolonged physiotherapy were the isokinetic limb symmetry index (LSI) for the quadriceps and the hamstrings as well as the Lysholm score. Results: At 4 postoperative months, 148 patients (31.4%) still had physiotherapy sessions. This group had performed 49 ± 14 physiotherapy sessions at the time of evaluation compared to 33 ± 9 sessions performed by the group that stopped physiotherapy at 3 months post-ACL reconstruction. The isokinetic knee LSI and the Lysholm score were not different between the two groups. Continued physiotherapy sessions were associated with female gender, previous high sport level, meniscal repair, lateral tenodesis and outpatient rehabilitation at the beginning of the rehabilitation management, while knee pain complications were not associated. Conclusions: No significant correlation was found between the number of physiotherapy sessions and the knee strength LSI or the Lysholm score. Prolonging patient physiotherapy sessions after 3 months post-ACL reconstruction seems ineffective in improving knee strength recovery and function.

Associations between paraspinal muscle characteristics and spinal curvature in conservatively treated adolescent idiopathic scoliosis: a systematic review

BACKGROUND CONTEXT

Children with adolescent idiopathic scoliosis (AIS) may show asymmetrical paraspinal muscle characteristics.

PURPOSE

To summarize the evidence regarding: (1) the associations between various paraspinal muscle characteristics and spinal curvature; (2) whether paraspinal muscle properties significantly differed between children with and without AIS; and (3) whether baseline paraspinal muscle characteristics predicted curve progression.

STUDY DESIGN/SETTING

Systematic literature review.

METHODS

Five databases (CINAHL, Academic Search Premier, MEDLINE, Scopus, and PubMed) were searched from inception to May 2022. This protocol was registered in the PROSPERO database of systematic reviews CRD 42020171263. The Critical appraisal skills program, the Appraisal Tool for Cross-Sectional Studies and Quality In Prognosis Studies tool were used to evaluate the risk of bias of the included studies. The strength of evidence of each identified association was determined by the Grading of Recommendations Assessment, Development, and Evaluation System (GRADE).

RESULTS

Of 1,530 identified citations, four cohort, 17 cross-sectional, and 23 case-control studies including 31 with low, nine with moderate and four with high risk of bias were included. Low to very low-strength evidence supported that the convex side of the curve had more type I muscle fibers, higher muscle volume and paraspinal muscle activity, while the concavity had more intramuscular fatty infiltration. Very low-strength evidence substantiated greater side-to-side surface electromyography signals during left trunk bending in prone lying, standing, and standing with perturbation between people with and without AIS. Also, low to very low-strength evidence supported that a larger side-to-side surface electromyography ratio at the lower end vertebra predicted curve progression.

CONCLUSIONS

Our review highlights that paraspinal muscles on the concavity of the curve demonstrate consistent changes (ie, altered muscle-related gene expression, muscle atrophy, increased fatty infiltration, reduced type I fibers, and reduced muscle activity), which may be the cause or consequence.

Acute Effect of Kinesiology Taping on Muscle Activation, Functionality and Proprioception in Patients With Knee Osteoarthritis: A Randomized Controlled Trial

Data on the mechanism of kinesiology taping (KT) for providing mechanical support, facilitating or inhibiting muscles, and increasing functionality in the treatment of knee osteoarthritis (OA) have been contradictory, with no study evaluating acute muscle activation. Our aim in this study was to determine the acute effect of KT applied to the rectus femoris muscle on this muscle's activation, functionality and proprioception in patients with knee osteoarthritis. We divided 40 individuals diagnosed with knee osteoarthritis into two groups: (a) KT group (taping with tension facilitation) and (b) a placebo group (taping with no tension facilitation). We applied taping to the participants' left and right side rectus femoris muscles for 30 minutes, but with muscle facilitation in the KT group and without tension in the placebo group. We assessed participants for muscle activation with surface electromyography (sEMG), for functionality with the Timed Up and Go Test (TUG), and for proprioception/joint sense with the Five Times Sit-to-Stand Test (5TSTS) before and after taping. Demographic and clinical characteristics of the groups before these interventions were similar (p > .05). Muscle activation did not change significantly in either group compared to before taping (p > .05), but there were improvements in both knees for proprioception/joint sense (p < .05). Both groups were similar in terms of functionality (5TSTS, TUG) results (p > .05). We concluded that KT applied bilaterally to the rectus femoris did not affect rectus femoris muscle activation and functionality in patients with knee OA, but it did improve proprioception.

Individuals With Chronic Ankle Instability Show Abnormalities in Maximal and Submaximal Isometric Strength of the Knee Extensor and Flexor Muscles

BACKGROUND

It has been shown that chronic ankle instability (CAI) leads to abnormalities in neuromuscular control of more proximal joints than the ankle. Although strength of the hip and the ankle muscles has been largely investigated providing concordant results, limited evidence with contrasting results has been reported regarding knee extensor and flexor muscles.

PURPOSE

To investigate maximal and submaximal isometric muscle strength in individuals with CAI.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifteen participants with unilateral CAI and 15 healthy matched controls were recruited. To quantify maximal strength, peak forces were recorded during a maximal isometric voluntary contraction of knee extensor and flexor muscles at 30° and 90° of knee flexion and normalized by the body weight of each participant. At both angles, submaximal isometric contractions at 20%, 50%, and 80% of the maximal voluntary isometric contraction were performed to analyze strength steadiness, in terms of coefficient of variation, and strength accuracy, in terms of absolute error. During all the assessments, knee extensor and flexor muscle activation was recorded by means of surface electromyography.

RESULTS

Knee flexor maximal isometric strength was significantly lower in the injured limb of individuals with CAI in comparison with healthy controls at both 30° (0.15 ± 0.05 vs 0.20 ± 0.05; P < .05) and 90° (0.14 ± 0.04 vs 0.18 ± 0.05; P < .05). Knee extensor and flexor steadiness was significantly lower (higher coefficient of variation) in both the injured and the noninjured limbs of individuals with CAI in comparison with healthy individuals at 90° and at 30° for knee flexor steadiness of the injured limb. Knee extensor and flexor accuracy was lower (higher absolute error) in both the injured and noninjured limbs of individuals with CAI in comparison with healthy individuals, mainly at 30°, while at 90° it was lower only in the injured limb. No differences between the 2 groups were found for maximal isometric strength of knee extensor muscles, as well as for muscle activations.

CONCLUSION

Individuals with CAI show abnormalities in maximal and submaximal isometric strength of knee flexor muscles, and submaximal strength of the knee extensor muscles. Further studies should deeply investigate mechanisms leading to these abnormalities.

CLINICAL RELEVANCE

Rehabilitation interventions should consider abnormalities of neuromuscular control affecting joints more proximal than the ankle in individuals with CAI.

REGISTRATION

NCT05273177 (ClinicalTrials.gov identifier).

The past and future of peri-operative interventions to reduce arthrogenic quadriceps muscle inhibition after total knee arthroplasty: A narrative review

Total knee arthroplasty (TKA) improves patient-reported function by alleviating joint pain, however the surgical trauma exacerbates already impaired muscle function, which leads to further muscle weakness and disability after surgery. This early postoperative strength loss indicates a massive neural inhibition and is primarily driven by a deficit in quadriceps muscle activation, a process known as arthrogenic muscle inhibition (AMI). To enhance acute recovery of quadriceps muscle function and long-term rehabilitation of individuals after TKA, AMI must be significantly reduced in the early post-operative period. The aim of this narrative review is to review and discuss previous efforts to mitigate AMI after TKA and to suggest new approaches and interventions for future efficacy evaluation. Several strategies have been explored to reduce the degree of post-operative quadriceps AMI and improve strength recovery after TKA by targeting post-operative swelling and inflammation or changing neural discharge. A challenge of this work is the ability to directly measure AMI and relevant contributing factors. For this review we focused on interventions that aimed to reduce post-operative swelling or improve knee extension strength or quadriceps muscle activation measured by twitch interpolation. For individuals undergoing TKA, the use of anti-inflammatory medications, tranexamic acid, cryotherapy, intra-articular drains, torniquets, and minimally invasive surgical techniques for TKA have limited benefit in attenuating quadriceps AMI early after surgery. However, interventions such as inelastic compression garments, voluntary muscle contractions, and neuro-muscular electrical stimulation show promise in mitigating or circumventing AMI and should continue to be refined and explored.

Efficacy on knee function of Kinesio taping among individuals with anterior cruciate ligament reconstruction: A systematic review

OBJECTIVE

This study aims to evaluate systematically the efficacy of Kinesio taping (KT) on the knee function of individuals who undergo anterior cruciate ligament reconstruction (ACLR).

METHODS

This study was registered in PROSPERO (registration number CRD42023399885) on February 26, 2023. Randomized controlled trials (RCTs) about the effects on the knee function of KT among individuals after ACLR were electronically searched from PubMed, Web of Science, Embase, The Cochrane Library, and EBSCO from inception to July 02, 2023. The outcome measures included six continuous variables: quadriceps strength, hamstring strength, knee swelling, knee flexion angle, Lysholm knee function score, and Visual Analog Scale (VAS) pain scores. The Cochrane Risk Bias Assessment Tool was used to evaluate the quality of the included literature.

RESULTS

Seven RCTs including 278 patients who underwent ACLR were included in the systematic review. One of three (33%) studies found a remarkable increase in quadricep strength associated with the use of KT compared with the control group. Two of two (100%) studies found substantial increases in hamstring strength associated with KT. Two of four (50%) studies reported KT reduced knee swelling. Two of five (40%) studies reported considerable improvements in knee flexion angle in the groups that used KT. All three (100%) studies found KT did not improve Lysholm knee function scores. Three of four (75%) studies noted a significant reduction in VAS pain scores associated with KT.

CONCLUSION

KT may help improve hamstring strength and reduce knee swelling and pain in patients after ACLR. Further studies are needed to determine the effects of KT on quadricep strength and knee flexion angle.

Therapeutic effect of knee extension exercise with single-joint hybrid assistive limb following total knee arthroplasty: a prospective, randomized controlled trial

The single-joint hybrid assistive limb (HAL-SJ), an exoskeletal robotic suit, offers functional improvement. In this prospective randomized controlled trial, we investigated the therapeutic effects of knee extension exercises using the HAL-SJ after total knee arthroplasty (TKA). Seventy-six patients with knee osteoarthritis were randomly assigned to HAL-SJ or conventional physical therapy (CPT) groups. The HAL-SJ group underwent exercise using the HAL-SJ for 10 days postoperatively, in addition to CPT; the CPT group underwent only CPT. Pain intensity and active and passive knee extension angles were evaluated preoperatively and on postoperative days 1-10 and weeks 2 and 4. Performance tests and Knee Injury and Osteoarthritis Outcome Scores (KOOS) were evaluated preoperatively and at postoperative weeks 2 and 4. Statistical analysis showed that the HAL-SJ group significantly improved active and passive knee extension angles compared with the CPT group. The HAL-SJ group showed immediate improvement in active knee extension angle through day 5. There were no significant differences in results between the performance tests and KOOS. Knee extension exercises with the HAL-SJ improved knee pain and the angle of extension in the acute phase after TKA.