Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives

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.

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.

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.

[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.

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.

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.

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.

Prevention of knee stiffness following ligament reconstruction: Understanding the role of Arthrogenic Muscle Inhibition (AMI)

The knee is a joint that is often injured in sport, with a large and increasing number of ligament tears and repairs; postoperative complications can lead to poor outcome, such as stiffness. Beyond the well-known and well-described intra- and extra-articular causes of postoperative stiffness, the present study introduces the concept of a central reflex motor inhibition mechanism called arthrogenic muscle inhibition (AMI). AMI occurs after trauma and can be defined as active knee extension deficit due to central impairment of Vastus Medialis Obliquus (VMO) contraction, often associated with spinal reflex hamstring contracture. This explains the post-traumatic flexion contracture that is so common after knee sprain. The clinical presentation of AMI is easy to detect in consultation, in 4 grades from simple VMO inhibition to fixed flexion contracture by posterior capsule retraction in chronic cases. After recent anterior cruciate ligament (ACL) tear, more than 55% of patients show AMI, reducible in 80% of cases by simple targeted exercises initiated in consultation. Practically, in patients who have sustained knee sprain, it is essential to screen for this reflex mechanism and assess reducibility, as AMI greatly aggravates the risk of postoperative stiffness. In case of hemarthrosis, we recommend joint aspiration, which provides immediate benefit in terms of pain and motor inhibition. In case of persistent AMI, classical electrostimulation and "cushion crush", as used by all physiotherapists, are ineffective. To reduce the risk of postoperative stiffness, no surgery should be considered until AMI has resolved. LEVEL OF EVIDENCE: expert opinion.

Changes in passive hamstring stiffness after primary anterior cruciate ligament reconstruction: A prospective study with comparison of healthy controls

BACKGROUND

The mechanical properties of knee flexors muscles contribute to reducing anterior cruciate ligament loading. This case-control study evaluated the passive knee flexors stiffness after primary anterior cruciate ligament reconstruction with comparison of healthy controls.

METHODS

After anterior cruciate ligament reconstruction, 88 participants (24.5 [8.6] years, 56,8% males) had two isokinetic tests at 4 and 8 postoperative months with measurement of the passive resistive torque of knee flexors and extensors/flexors strength. In the control group, 44 participants (24.5 [4.3] years, 56,8% males) had one visit with the same procedures. Passive knee flexors stiffness was calculated as the slope of the passive torque-angle curve on the last 10° of knee extension (Nm/°). We investigated the impact of timing and type of surgery (autograft and combined meniscus repair) and persistent knee extension deficits on knee flexors stiffness.

FINDINGS

At 4 and 8 postoperative months, passive knee flexors stiffness was lower on the operated limb than on the non-operated limb (P < 0.001) but both limbs had significant lower values than controls (P < 0.001). Stiffness was positively correlated with knee flexors strength (P < 0.010), and knee flexors stiffness at 4 months was lower in individuals who underwent surgery <6 months from injury (P = 0.040). Knee extension deficit or the type of surgery did not have a significant influence on knee flexors stiffness.

INTERPRETATION

Similarly to neuromuscular factors that are traditionally altered after anterior cruciate ligament reconstruction, evaluating passive knee flexors stiffness changes over time could provide supplementary insights into postoperative muscle recovery.

Bilateral neuromuscular control in patients one year after unilateral ACL rupture or reconstruction. A cross-sectional study

Objectives

To compare bilateral neuromuscular control in patients one year after anterior cruciate ligament reconstruction (ACL-R) or conservative treatment (ACL-C) to healthy controls (ACL-I).

Design

Cross-sectional study.

Setting

Electromyography of vastus medialis (VM) and lateralis (VL), biceps femoris (BF) and semitendinosus (ST) was recorded during stair descent and anterior tibial translation. Each step of stair descent was divided into pre-activity, weight-acceptance and push-off phase. Pre-activation, short, medium (MLR) and long latency responses (LLR) were defined for reflex activity.

Participants

N = 38 patients one year after ACL reconstruction (ACL-R), N = 26 participants with conservative treatment one year after ACL rupture (ACL-C), N = 38 healthy controls with an intact ACL (ACL-I).

Main outcome measures

Normalized root mean squares per muscle and phase (α = 0.05).

Results

During stair descent, within-group leg differences were found for the quadriceps in ACL-R during all phases and for the BF in ACL-C during weight-acceptance. Between-group leg differences were found for BF in both patient groups compared to ACL-I during push-off.Between-group differences in pre-activation for VM between ACL-R and ACL-C, and between ACL-C and ACL-I were found, and as LLR between patients and ACL-R versus ACL-I. Pre-activation of BF and MLR of ST differed for each patient group compared to ACL-I.

Conclusions

Bilateral neuromuscular alterations are still present one year after ACL rupture or reconstruction.

A Portable, Neurostimulation-Integrated, Force Measurement Platform for the Clinical Assessment of Plantarflexor Central Drive

Plantarflexor central drive is a promising biomarker of neuromotor impairment; however, routine clinical assessment is hindered by the unavailability of force measurement systems with integrated neurostimulation capabilities. In this study, we evaluate the accuracy of a portable, neurostimulation-integrated, plantarflexor force measurement system we developed to facilitate the assessment of plantarflexor neuromotor function in clinical settings. Two experiments were conducted with the Central Drive System (CEDRS). To evaluate accuracy, experiment #1 included 16 neurotypical adults and used intra-class correlation (ICC2,1) to test agreement of plantarflexor strength capacity measured with CEDRS versus a stationary dynamometer. To evaluate validity, experiment #2 added 26 individuals with post-stroke hemiparesis and used one-way ANOVAs to test for between-limb differences in CEDRS' measurements of plantarflexor neuromotor function, comparing neurotypical, non-paretic, and paretic limb measurements. The association between paretic plantarflexor neuromotor function and walking function outcomes derived from the six-minute walk test (6MWT) were also evaluated. CEDRS' measurements of plantarflexor neuromotor function showed high agreement with measurements made by the stationary dynamometer (ICC = 0.83, p < 0.001). CEDRS' measurements also showed the expected between-limb differences (p's < 0.001) in maximum voluntary strength (Neurotypical: 76.21 ± 13.84 ft-lbs., Non-paretic: 56.93 ± 17.75 ft-lbs., and Paretic: 31.51 ± 14.08 ft-lbs.), strength capacity (Neurotypical: 76.47 ± 13.59 ft-lbs., Non-paretic: 64.08 ± 14.50 ft-lbs., and Paretic: 44.55 ± 14.23 ft-lbs.), and central drive (Neurotypical: 88.73 ± 1.71%, Non-paretic: 73.66% ± 17.74%, and Paretic: 52.04% ± 20.22%). CEDRS-measured plantarflexor central drive was moderately correlated with 6MWT total distance (r = 0.69, p < 0.001) and distance-induced changes in speed (r = 0.61, p = 0.002). CEDRS is a clinician-operated, portable, neurostimulation-integrated force measurement platform that produces accurate measurements of plantarflexor neuromotor function that are associated with post-stroke walking ability.

Academic Department of Military Rehabilitation (ADMR): avoiding the pitfalls of 'the Walker Dip'

A key research theme identified during the 2021 Strategic Delivery Plan (SDP) for Defence Medical Services (DMS) Research was preventing and treating musculoskeletal injury (MSKI). MSKI is a significant burden to military populations globally, reducing both operational strength and force readiness. It is therefore essential that research is conducted to gain a greater understanding of the epidemiology, aetiology and risk factors associated with MSKI to develop targeted prevention strategies and rehabilitation interventions. The Academic Department of Military Rehabilitation (ADMR) and the recently established MSKI research-theme working group must use a combination of balance and flexibility when coordinating research priorities to ensure they align and reflect both higher level DMS and UK Defence Rehabilitation practitioner-driven priorities. This article describes the response ADMR have taken to meet and align with the requirements of the 2021 SDP.

Tactile stimulation restores inhibited stretch reflex attributable to attenuation of Ia afferents during surprise landing

Arthrogenic muscle inhibition (AMI) is induced by pathological knee conditions. The present study aimed to investigate the effect of tactile stimulation on reflex changes induced by simulated AMI during unpredictable landing performances. Twenty participants performed six unilateral landing tasks: 15 cm normal landing (15NL), 30 cm normal landing (30NL), surprise landing (SL), 30 cm normal landing following vibration (30NLV), SL following vibration (SLV), and SL following vibration with Kinesiology tape (SLK). For SL, the solid landing platform (15 cm) was removed and replaced by a false floor. Since the false floor dislodged easily under load, participants unpredictably fell through the platform to the actual landing surface 15 cm below. After completing 15NL, 30NL, and SL, vibration was applied to participants' knees to induce neurological changes similar to AMI. After vibration, participants performed 30NLV, SLV, and SLK in a random order. EMG signals in the post-landing short latency (31-60 ms) and medium latency (61-90 ms) periods were examined. EMG signals from the vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF) were recorded and compared between tasks. EMG signals of all muscles in SL were significantly enhanced in the medium latency period as compared with 30NL. Enhanced EMG signals in SL were suppressed by vibration stimulation in the VL, but the suppressed EMG signals were restored after cutaneous stimulation with Kinesiology tape (p < 0.01). Our findings suggest that AMI could alter motor control patterns during unpredictable landing and that tactile stimulation could restore the altered motor control to a normal state.

Serum vitamin D insufficiency is correlated with quadriceps neuromuscular functions in patients with anterior cruciate ligament injury: A preliminary study

Background

This study aimed to investigate the correlations of serum vitamin D insufficiency with quadriceps neuromuscular function in patients with anterior cruciate ligament (ACL) injury.

Methods

A cross-sectional study was conducted. Eighteen patients with a primary, unilateral ACL injury who had insufficient serum vitamin D concentrations (<30 ng/ml) were recruited for the study. Bilateral quadriceps neuromuscular function, including maximal strength, the speed of rapid contraction, and inhibition, were measured on an isokinetic dynamometer with the hip and the knee joint flexion at 90° and 45°, respectively. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC); the speed of rapid contraction was quantified by the rate of torque development (RTD), which was divided into the early (RTD0-50) and the late phase (RTD100-200); quadriceps inhibition was quantified by the central activation ratio (CAR). Serum vitamin D concentration was quantitatively determined by serum 25(OH)D concentration measured by the 25(OH)D ELISA kit. The Spearman rank correlation analysis was used to examine the correlation between the vitamin D concentration and bilateral quadriceps MVIC, RTD0-50, RTD100-200, and CAR, respectively.

Results

The results of Spearman rank correlation analyses showed that the serum 25(OH)D concentration was significantly correlated with bilateral quadriceps MVIC (injured: r = 0.574, p = 0.013; uninjured: r = 0.650, p = 0.003) and RTD0-50 (r = 0.651, p = 0.003), and CAR (r = 0.662, p = 0.003) on the uninjured limb. However, no significant correlations were found between the serum 25(OH)D concentration and the other outcomes.

Conclusions

The serum vitamin D concentration correlates with quadriceps neuromuscular function in patients with ACL injury who had vitamin D insufficiency.

Influence of strength and balance ability on functional performance in the involved and uninvolved sides after anterior cruciate ligament reconstruction

BACKGROUND

The restoration and management of the uninvolved side have been emphasized to prevent a second anterior cruciate ligament (ACL) injury and to ensure that athletes return to sports after ACL reconstruction.

OBJECTIVE

To determine the factors influencing the single leg hop test (SLHT) and single leg vertical jump test (SLVJT) at 1 year postoperatively after ACL reconstruction in both the involved and uninvolved sides.

METHODS

Ninety-four patients who underwent ACL reconstruction were assessed at 1 year postoperatively. Multiple regression models included eight independent variables with two dependent variables (SLHT and SLVJT.), each on the involved and uninvolved side.

RESULTS

On the involved side, the Y balance test (YBT), extensor peak torque per body weight (PT/BW), Biodex balance system anteroposterior index (BBS-API), and sex accounted for 53.9% of the variance in SLHT (P= 0.002), and extensor PT/BW and YBT accounted for 26.3% of the variance in SLVJT (P= 0.027). On the uninvolved side, YBT, sex, age, BBS-API, and flexor PT/BW accounted for 47.0% of the variance in SLHT (P= 0.046), and flexor PT/BW, YBT, and age accounted for 44.9% of the variance in SLVJT (P= 0.002).

CONCLUSION

Knee extensor strength on the involved side and flexor strength on the uninvolved side influence the two functional performance tests. The YBT was an important factor in the two functional performance tests in both sides. Anteroposterior stability was the only factor that influenced the SLHT bilaterally.

What interventions can treat arthrogenic muscle inhibition in patients with chronic ankle instability? A systematic review with meta-analysis

PURPOSE

To identify, critically appraise, and synthesize the existing evidence regarding the effects of therapeutic interventions on arthrogenic muscle inhibition (AMI) in patients with chronic ankle instability (CAI).

MATERIALS AND METHODS

Two reviewers independently performed exhaustive database searches in Web of Science, PubMed, Medline, CINAHL, and SPORTDiscus.

RESULTS

Nine studies were finally included. Five types of disinhibitory interventions were identified: focal ankle joint cooling (FAJC), manual therapy, fibular reposition taping (FRT), whole-body vibration (WBV), and transcranial direct current stimulation (tDCS). There were moderate effects of FAJC on spinal excitability in ankle muscles (g = 0.55, 95% CI = 0.03-1.08, p = 0.040 for the soleus and g = 0.54, 95% CI = 0.01-1.07, p = 0.046 for the fibularis longus). In contrast, manual therapy, FRT, WBV were not effective. Finally, 4 weeks of tDCS combined with eccentric exercise showed large effects on corticospinal excitability in 2 weeks after the intervention (g = 0.99, 95% CI = 0.14-1.85 for the fibularis longus and g = 1.02, 95% CI = 0.16-1.87 for the tibialis anterior).

CONCLUSIONS

FAJC and tDCS may be effective in counteracting AMI. However, the current evidence of mainly short-term studies to support the use of disinhibitory interventions is too limited to draw definitive conclusions.

Incidence of and Risk Factors for Arthrogenic Muscle Inhibition in Acute Anterior Cruciate Ligament Injuries: A Cross-Sectional Study and Analysis of Associated Factors From the SANTI Study Group

BACKGROUND

Arthrogenic muscle inhibition (AMI) is a process in which neural inhibition after injury or surgery to the knee results in quadriceps activation failure and knee extension deficit.

PURPOSE

To determine the incidence and spectrum of the severity of AMI after acute anterior cruciate ligament (ACL) injury using the Sonnery-Cottet classification, to determine the interobserver reliability of the classification system, and to investigate potential important factors associated with AMI after ACL injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Consecutive patients who had an acute ACL injury between October 2021 and February 2022 were considered for study inclusion. Eligible patients underwent a standardized physical examination at their first outpatient appointment. This included an assessment of quadriceps inhibition, identification of any extension deficits, and grading of AMI and its reversibility according to the Sonnery-Cottet classification.

RESULTS

A total of 300 consecutive patients with acute ACL ruptures were prospectively enrolled in the study. Of them, 170 patients (56.7%) had AMI. Patients evaluated with AMI showed a significantly inferior Lysholm score, International Knee Documentation Committee score, Simple Knee Value, and Knee injury and Osteoarthritis Outcome Score than patients without AMI (P < .0001). Multivariate analysis revealed that the presence of effusion, concomitant injuries, and high pain scores were associated with a significantly greater risk of AMI. Additional associations with the presence of AMI included a short duration between injury and evaluation, the use of crutches, and using a pillow as a support at night. In contrast, a previous ACL injury was associated with significantly lower odds of developing AMI (OR, 0.025; 95% CI, 0-0.2; P = .014). Among the 170 patients with AMI, 135 patients (79%) showed a resolution of their inhibition at the end of the consultation after application of simple exercises; the remaining 35 patients required specific rehabilitation. Interobserver reliability of the classification system was almost perfect (95% CI, 0.86-0.99).

CONCLUSION

AMI occurs in over half of patients with acute ACL injuries. When it occurs, it is easily reversible in the majority of patients with simple exercises targeted at abolishing AMI. The presence of "red flags" should increase the index of suspicion for the presence of AMI, and these include the presence of an effusion, high pain scores, a short time between injury and evaluation, multiligament injuries, the use of crutches, and using a pillow as a support at night. Patients with a history of ipsilateral or contralateral ACL injury are at a significantly lower risk of AMI than those with a first-time ACL injury.

Comparison of the clinical outcomes following total knee arthroplasty in osseous ankylosed and non-ankylosed knees using propensity-score matching

OBJECTIVES

Few studies have compared the clinical outcomes and complications of total knee arthroplasty (TKA) in patients with and without osseous ankylosed knees. Thus, we investigated the clinical outcomes and complications of TKA in patients with osseous ankylosed knees using a propensity-score matching method.

METHODS

Thirteen knees in the osseous ankylosed-knees group and 13 knees in the non-ankylosed-knees group were included after excluding those with less than 2 years of follow-up or a lack of data and after propensity-score matching. The American Knee Society Score-knee (AKSS-knee), AKSS-function, knee-flexion angle, knee-extension angle, knee range of motion (ROM) before and after TKA, and the number of knees with postoperative complications were evaluated as primary outcomes.

RESULTS

The AKSS-knee, AKSS-function, knee-flexion angle, and knee ROM in the osseous ankylosed-knees group after TKA were significantly lower than those in the non-ankylosed-knees group. The knee-extension angle after TKA and number of knees with postoperative complications within 2 years were not significantly different between the two groups.

CONCLUSIONS

The clinical results of TKA in patients with osseous ankylosed knees were inferior to those in patients with non-ankylosed knees.

Effect of adding hip exercises to general rehabilitation treatment of knee osteoarthritis on patients' physical functions: a randomized clinical trial

BACKGROUND

Hip adductor and abductor strength were both reduced in KOA patients. But to date, most of the researches have only focused on quadriceps combined with hip abductor strengthening versus quadriceps strengthening.

OBJECTIVE

The aim of the study is to evaluate the effect of adding hip abductor and adductor strengthening to quadriceps strengthening on lower limb strength, knee pain and physical function in patients with medial compartmental knee osteoarthritis.

METHODS

In this study, 42 participants, were randomly divided into two groups: the general treatment group (GT group) and the added-hip-exercise group (AH group). All participants were given a general rehabilitation treatment. The AH group performed hip abductor and adductor strengthening in addition to the general rehabilitation treatment. Knee and hip muscle strength, Five Times Sit-to-Stand Test (FTSST), the Timed Up and Go Test (TUGT), Numerical Rating Scale (NRS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were assessed at baseline and 6 weeks. A two-sided 2-sample unpaired t test was performed to compare the difference in mean change scores between AH and GT groups.

RESULTS

Finally, 36 participants completed the study: both groups consist of 18 participants. In the per-protocol analysis, the AH group had a greater improvement in knee extension strength (mean changes, 7.84 versus 36.48; P < 0.001) and hip abduction strength (mean changes, 5.05 versus 26.62; P = 0.001) than the control group. Similarly, the AH group had a greater improvement in the FTSST time (mean changes, 0.40 s versus 3.57 s; P < 0.001) and the TUFT time (mean changes, 0.18 s versus 1.67 s; P = 0.002) than the GH group. No statistical difference was found in the change of WOMAC pain scores and NRS between the 2 groups.

CONCLUSIONS

Older adults with knee OA in the AH group had superior muscle strength, symptoms and daily activity performance at the 6th week than those in the GT group. And adding hip exercises could expedite improvement of pain at the 2th week, but not at the 6th week.

TRIAL REGISTRATION

Clinical trial registration numbers and date of registration: ChiCTR-IOR-16009124, Registered 30 August 2016.

Rehabilitation of Patients with Arthrogenic Muscular Inhibition in Pathologies of Knee Using Virtual Reality

Arthrogenic muscle inhibition (AMI) refers to muscular alterations that are generated, producing biomechanical motor control and movement problems, leading to deficiencies in strength and atrophy. Currently, there exist methods that involve virtual reality (VR) and have been well perceived by physiotherapists. The present research measured the potential benefits in terms of therapeutic adherence and speed of recovery, through a comparative analysis in a healthcare provider institution, in Medellín, Colombia, with and without the aid of VR. For this purpose, dynamometry, and surface electromyography (sEMG) signal acquisition tools were used. The treatment involved neuromodulation, ranges of motion and mobility work, strengthening and reintegration into movement, complemented with TENS, NMENS and therapeutic exercise, where the patient was expected to receive a satisfactory and faster adherence and recovery. A group of 15 people with AMI who include at least 15 min of VR per session in their treatment were compared with another group who received only the base treatment, i.e., the control group. Analyzing the variables individually, it is possible to affirm that VR, as a complement, statistically significantly improved the therapeutic adherence in 33.3% for CG and 37.5% for IG. Additionally, it increased strength with both legs, the symmetry between them, and decreased the level of pain and stiffness that is related to mobility.

Early application of extracorporeal shock wave therapy improves pain control and functional scores in patients undergoing total knee arthroplasty: a randomized controlled trial

PURPOSE

The use of biophysical stimuli produced by extracorporeal shock wave therapy (ESWT) can improve the rehabilitation treatment of patients undergoing total knee arthroplasty (TKA). The aim of our study is to evaluate the short-term efficacy of early postoperative ESWT in combination with physiotherapy in terms of pain reduction and motor function recovery of patients undergoing TKA and compare it with conventional physiotherapy treatment.

METHODS

Fifty-six patients undergoing TKA were enrolled in the study from January 2019 to February 2020. Patients received two sessions of physiotherapy daily, with (experimental group) or without (control group) four sessions of ESWT within seven days after surgery. Patients were prospectively evaluated at baseline and at post-operative day two and seven. Assessment included active knee range of motion (aROM), timed up and go (TUG) test, visual analogue scale (VAS) for pain, and Borg scale.

RESULTS

Fifty patients completed the study. Both treatments proved to be effective in reducing pain and improving the knee range of motion and functional scores at seven days after surgery: the aROM in the ESWT group was 36.8 ± 11.0 grades (p < 0.001), while in control group was 19.8 ± 7.8 grades (p < 0.001). TUG, VAS, and BORG scores showed a similar trend. Comparative analysis revealed superior clinical results for the experimental group in all the outcomes, in particular aROM (96.0 ± 5.40 vs. 81.20 ± 11.01, p < 0.001) and TUG test (17.4 ± 5.61 vs. 21.24 ± 5.88, p < 0.001), at day seven after surgery.

CONCLUSION

Early application of ESWT in addition to physiotherapy can positively influence the rehabilitation process after TKA. The treatment proved to be well tolerated and safe. Preliminary results demonstrated better pain control and functional scores compared to physiotherapy alone.

Fatigue-induced Landing Alterations in ACL Reconstructed Athletes after Return-to-Sport

At the time of return-to-sport, anterior cruciate ligament reconstructed athletes still show altered neuromechanics in their injured leg during single leg hopping tasks. Part of these alterations can be magnified when these athletes are fatigued. So far, little is known whether fatigue-induced landing alterations persist after return-to-sport. Therefore, the aim of this study was to evaluate whether these alterations persist in the six months following return-to-sport. Sixteen anterior cruciate ligament reconstructed athletes performed five unilateral hop tasks before and after a fatigue protocol. The hop tasks were executed at three different time points (return-to-sport, 3 and 6 months post-return-to-sport). A 2-by-3 repeated measures ANOVA was performed to evaluate whether fatigue-induced landing alterations persisted 3 and 6 months following return-to-sport. At 6 months following return-to-sport, fatigue still induces a reduction in hamstring medialis activation and an increase in the knee abduction moment during a vertical hop with 90-degree inward rotation. Most fatigue-induced landing alterations present at the time of return-to-sport normalize after resumption of sports activities. However, a larger knee abduction moment in the injured leg after resumption of sports activities can still be observed.

Neuromuscular Characteristics of Unilateral and Bilateral Maximal Voluntary Isometric Contractions following ACL Reconstruction

Despite the advancement of diagnostic surgical techniques in anterior cruciate ligament (ACL) reconstruction and rehabilitation protocols following ACL injury, only half of the athletes return to sports at a competitive level. A major concern is neuromechanical dysfunction, which occurs with injuries persisting in operated and non-operated legs following ACL rehabilitation. One of the criteria for a safe return to sports participation is based on the maximal voluntary isometric contraction (MVIC) performed unilaterally and a comparison between the 'healthy knee' and the 'operated knee'. The present study aimed to investigate MVIC in athletes following ACL rehabilitation during open kinetic chain exercise performed unilaterally and bilateral exercises. Twenty subjects participated in the present investigation: 10 male athletes of regional-national level (skiers, rugby, soccer, and volleyball players) who were previously operated on one knee and received a complete rehabilitation protocol (for 6-9 months) were included in the ACL group (age: 23.4 ± 2.11 years; stature: 182.0 ± 9.9 cm; body mass: 78.6 ± 9.9 kg; body mass index: 23.7 ± 1.9 kg/m2), and 10 healthy male athletes formed the control group (CG: age: 24.0 ± 3.4 years; stature: 180.3 ± 10.7 cm; body mass: 74.9 ± 13.5 kg; body mass index: 22.8 ± 2.7 kg/m2). MVICs synchronised with electromyographic (EMG) activity (recorded on the vastus lateralis, vastus medialis, and biceps femoris muscles) were performed during unilateral and bilateral exertions. The rate of force development (RFD) and co-activation index (CI) were also calculated. The differences in the MVIC and RFD between the two legs within each group were not significant (p > 0.05). Vastus lateralis EMG activity during MVIC and biceps femoris EMG activity during RFD were significantly higher in the operated leg than those in the non-operated leg when exertion was performed bilaterally (p < 0.05). The CI was higher in the operated leg than that in the non-operated leg when exertion was performed bilaterally (p < 0.05). Vice versa, vastus medialis EMG activity during RFD was significantly higher in the right leg than that in the left leg when exertion was performed bilaterally (p < 0.05) in the CG. MVICs performed bilaterally represent a reliability modality for highlighting neuromechanical asymmetries. This bilateral exercise should be included in the criteria for a safe return to sports following ACL reconstruction.

Early triage of a patient with metastatic melanoma presenting as mechanical knee pain - a case report

Physical therapists (PTs) working in primary care settings commonly encounter mechanical causes of knee pain. Non-mechanical causes of knee pain, such as bone tumors, are rare, and therefore, PTs often have a low index of suspicion regarding sinister pathology. The purpose of this case report is to describe the physical therapist's clinical reasoning process for a 33-year-old female presenting with medial knee pain and a subsequent history of metastatic melanoma. Initially, subjective and objective testing pointed to a mechanical internal derangement of the knee. However, symptom progression and poor treatment responses between physical therapy visits 2 and 3 raised suspicions as to the cause of the knee pain. This prompted an orthopedic referral and medical imaging, revealing a large bone tumor invading the medial femoral condyle, which was further characterized as metastatic melanoma by a specialty oncology team. Further imaging revealed several metastatic subcutaneous, intramuscular and cerebral lesions. This case highlights the importance of the ongoing medical screening process, including the monitoring of symptoms and treatment responses.

Persistence of neuromuscular activation deficit in the lower limb at 3-years of follow-up after ACL reconstruction surgery

BACKGROUND

Almost all patients experience neuromuscular disorders of the quadriceps after knee trauma or surgery such as anterior cruciate ligament (ACL) reconstruction. This phenomenon is described in literature as arthrogenic muscle inhibition (AMI). It can be detrimental to patients and cause complications. However, few studies have evaluated the long-term persistence of deficits arising from this, following ACL reconstruction.

PURPOSE

By comparing neuromuscular activation in the lower limb after ACL reconstruction with the unaffected lower limb, after more than 3-years of follow-up, this study aimed to evaluate the possible persistence of long-term deficits after surgery.

METHODS

Fifty-one patients who underwent ACL reconstruction in 2018 were included in the study, with a minimum follow-up of 3 years. The neuromuscular activation deficit was assessed using the Biarritz Activation Score-Knee (BAS-K), whose intra- and inter-observer reproducibility was also evaluated. The ACL-RSI, KOOS, SANE Leg, Tegner and IKDC scores were also evaluated.

RESULTS

The mean BAS-K score of the knee that underwent surgery was 21.8/50 versus 37.9/50 in the healthy knee (p < 0.05). The SANE leg score was 76.8/100 versus 97.6/100 (p < 0.05). The mean IKDC was 84.17 (±12.7). The mean KOOS was 86.2 (±9.2). The mean ACL-RSI was 70 (±7.9) and the Tegner score was 6.3 (±1.2). Intra- and inter-observer reproducibility was satisfactory for the BAS-K score.

CONCLUSION

We found that the neuromuscular activation deficit was high (roughly 42%) at more than 3-years of follow-up after ACL reconstruction. The deficit is not limited to the quadriceps and affects the whole limb. Our findings highlight the need for appropriate rehabilitation after ACL surgery, targeting the corticospinal level in particular.

LEVEL OF EVIDENCE III

prognostic retrospective case-control study.

Eccentric Exercise as a Potent Prescription for Muscle Weakness After Joint Injury

Lengthening contractions (i.e., eccentric contractions) are capable of uniquely triggering the nervous system and signaling pathways to promote tissue health/growth. This mode of exercise may be particularly potent for patients suffering from muscle weakness after joint injury. Here we provide a novel framework for eccentric exercise as a safe, effective mode of exercise prescription for muscle recovery.

Editorial Commentary: Limited Preoperative Range of Motion Is Associated With Range of Motion Deficits After Anterior Cruciate Ligament Reconstruction: "If the Knee Is Not Straight, Wait"

Optimal timing of anterior cruciate ligament reconstruction (ACLR) remains under debate. Prolonging time between injury and ACLR risks damaging the meniscus and chondral surface, as well as delays return to play. Early ACLR may be associated with postoperative stiffness or arthrofibrosis. We emphasize that optimal timing for ACLR depends on criterion-based return of knee range of motion and quadriceps strength, not a quantitative temporal period. The length of time is far less important that the quality of prereconstruction care provided. Prereconstruction care includes "prehabilitation," including prone hangs focusing on optimizing knee range of motion, postinjury effusion resolution, and mentally preparing the patient for postoperative expectations. Defining preoperative criteria for proceeding with surgery is crucial to decrease the risk of arthrofibrosis. Some patients meet these criteria within 2 weeks, whereas others linger to 10 weeks. Reduction in arthrofibrosis requiring surgical intervention is multifactorial and not solely dependent on the length of time between injury and intervention.

Clinic and Home-Based Exercise with Blood Flow Restriction Resolves Thigh Muscle Atrophy after Anterior Cruciate Ligament Reconstruction with the Bone-Patellar Tendon-Bone Autograft: A Case Report

Anterior cruciate ligament reconstruction (ACLR) results in thigh muscle atrophy. Of the various interventions proposed to mitigate thigh muscle atrophy, exercise with blood flow restriction (BFR) appears safe and effective. Some literature suggests daily exposure to exercise with BFR may be indicated during the early phase of ACLR rehabilitation; this case report outlines the methodology utilized to prescribe clinic- and home-based BFR within an outpatient rehabilitation program. A 15-year-old male soccer player suffered a left knee injury involving the anterior cruciate ligament and both menisci. He underwent ACLR and completed exercise with BFR as part of his clinic- and home-based rehabilitation program, which included practical blood flow restriction during home-based rehabilitation. After 16 weeks of rehabilitation, surgical limb thigh girth values were objectively larger than the non-surgical limb (surgical, 52.25 cm; non-surgical 50 cm), as well as the multi-frequency bioelectrical impedance analysis of his lower-extremity lean body mass (surgical limb, 10.37 kg; non-surgical limb, 10.02 kg). The findings of this case report suggest that the inclusion of clinic- and home-based BFR within an outpatient rehabilitation program may be indicated to resolve thigh muscle atrophy early after ACLR.

Altered Knee Loading Following Primary ACL Repair versus ACL Reconstruction

Background

ACL repair (ACL-r) has recently gained renewed clinical interest for treatment of ACL tears. ACL-r has several potential benefits over ACL reconstruction (ACL-R) including maintaining the native ACL innervation and blood supply, no graft site morbidity, and possible improved knee biomechanics and decrease in osteoarthritis. The purpose of this study was to assess for differences in metrics of knee joint loading during a single limb squat task between individuals following a primary ACL-r versus those who underwent a standard ACL-R with a patella bone-tendon-bone autograft.

Study type

Case Control Study.

Methods

The ACL-r group [n: 15, age(yrs): 38.8±13.9] sustained a proximal ACL disruption that was amenable to repair, while the ACL-R group [n: 15, age(yrs): 25.60±1.7] underwent primary reconstruction with patella bone-tendon-bone autograft. At 12-weeks post-operation, both groups completed the IKDC questionnaire and biomechanical testing during performance of the single limb squat. Bilateral peak knee extension moment and total knee joint power as a measure of eccentric loading (contraction) during the descent phase of the squat were calculated on the surgical and non-surgical limb and averaged across the middle three of five trials. Participants also completed quadriceps strength testing on both limbs three months after surgery on an isokinetic dynamometer at 60°/sec. LSI (Limb Strength Index) was calculated for all variables. Separate ANCOVAs were performed on each biomechanical variable to examine differences between groups.

Results

The ACL-r had a significantly greater peak knee extension moment LSI (ACL-r: 78.46±5.79%; ACL-R: 56.86±5.79%; p=0.019, ηp2=.186) and total knee joint power LSI (ACL-r: 72.47±7.39%; ACL-R: 39.70±7.39%, p=0.006, ηp2=.245) than the ACL-R group. The ACL-r also had a significantly greater quadriceps LSI than the ACL-R group (ACL-r: 66.318±4.61%, ACL-R: 48.03±4.61%, p=0.013, ηp2=.206).

Conclusions

Individuals following ACL-r demonstrate increased knee joint loading symmetry during a single leg squat task and greater quadriceps strength symmetry at 12 weeks post-surgery compared to those who underwent ACL-R.

Level of Evidence

3.

Randomized controlled trial to compare conventional physiotherapy with task-oriented exercises after total hip replacement

BACKGROUND

Different interventions are used during rehabilitation after hip replacement surgery, but it is unclear if task-oriented exercise is more effective than conventional physiotherapy.

OBJECTIVE

This study compared the effectiveness of conventional physiotherapy (CPT) programme with task-oriented exercise (TOE) on hip pain, function, static and dynamic balance during the early rehabilitation stage after total hip replacement.

METHODS

This randomized controlled parallel-group trial was executed in an inpatient physical medicine and rehabilitation centre. The study included 40 patients who were randomly classified into CPT and TOE groups (n= 20 in each). Hip pain (assessed by visual analogue scale), function in the operated leg (assessed by modified Harris Hip Score, mHHS), static balance (assessed by Abili Balance analyser system) and dynamic balance (assessed by Berg Balance Scale) were evaluated at baseline and after 18 days of rehabilitation. Cohen's effect size (d) was calculated.

RESULTS

Greater pain reduction (p< 0.05; d= 0.08) was observed after TOE (1.6 ± 0.68 scores) compared with the CPT programme (2.2 ± 0.83 scores). Hip function assessed by the modified mHHS improved more (p< 0.05; d= 0.30) in the TOE group (73.45 ± 6.23 scores) than in the CPT group (54.90 ± 6.28 scores). Static balance improved significantly in both groups after the interventions but did not differ significantly between the groups. The improvement in dynamic balance was significantly greater (p< 0.05; d= 0.45) after TOE (50.55 ± 1.57 scores) than after CPT (38.55 ± 3.43 scores).

CONCLUSION

Both interventions reduced pain and improved function of the operated leg and static and dynamic balance. The effect on hip function was superior for TOE compared with CPT.

Brain activity associated with quadriceps strength deficits after anterior cruciate ligament reconstruction

Prolonged treatment resistant quadriceps weakness after anterior cruciate ligament reconstruction (ACL-R) contributes to re-injury risk, poor patient outcomes, and earlier development of osteoarthritis. The origin of post-injury weakness is in part neurological in nature, but it is unknown whether regional brain activity is related to clinical metrics of quadriceps weakness. Thus, the purpose of this investigation was to better understand the neural contributions to quadriceps weakness after injury by evaluating the relationship between brain activity for a quadriceps-dominated knee task (repeated cycles of unilateral knee flexion/extension from 45° to 0°), , and strength asymmetry in individuals returned to activity after ACL-R. Forty-four participants were recruited (22 with unilateral ACL reconstruction; 22 controls) and peak isokinetic knee extensor torque was assessed at 60°/s to calculate quadriceps limb symmetry index (Q-LSI, ratio of involved/uninvolved limb). Correlations were used to determine the relationship of mean % signal change within key sensorimotor brain regions and Q-LSI. Brain activity was also evaluated group wise based on clinical recommendations for strength (Q-LSI < 90%, n = 12; Q-LSI ≥ 90%, n = 10; controls, all n = 22 Q-LSI ≥ 90%). Lower Q-LSI was related to increased activity in the contralateral premotor cortex and lingual gyrus (p < .05). Those who did not meet clinical recommendations for strength demonstrated greater lingual gyrus activity compared to those who met clinical recommendations Q-LSI ≥ 90 and healthy controls (p < 0.05). Asymmetrically weak ACL-R patients displayed greater cortical activity than patients with no underlying asymmetry and healthy controls.

Arthrogenic muscle inhibition manifests in thigh musculature motor unit characteristics after anterior cruciate ligament injury

Joint trauma induces a presynaptic reflex inhibition termed arthrogenic muscle inhibition (AMI) that prevents complete activation of muscles. Reduced motor unit (MU) output is a hypothesised mechanism for persistent strength deficits. The objective of this study was to determine MU characteristics of thigh musculature and determine how they change with anterior cruciate ligament (ACL) injury compared to healthy controls. A randomised protocol of knee flexion/extension isometric contractions (10-50% maximal voluntary isometric contraction) was performed for each leg with surface EMG 5-pin array electrodes placed on the vastus medialis, vastus lateralis, semitendinosus and biceps femoris. Longitudinal assessments for average rate coding, recruitment thresholds and MU action potentials were acquired at 6-month intervals. With exception of the vastus medialis, all thigh musculature of ACL-injured demonstrated smaller MU action potential peak-to-peak amplitude. For average rate coding, ACL-injured demonstrated lower coding rates than Controls for the quadriceps (p < .05) and higher rates than Controls for the hamstrings (p < .05). These MU characteristics were different from Controls after ACL reconstruction up to 12 months post-surgery, yet maximal strength increased during this time frame. As thigh MU characteristics are known across phases of ACL rehabilitation, future studies can assess these patterns of motor control and their potential to determine risk of re-injury. Further, future rehabilitation can target specific intervention programmes to restore motor control.HighlightsMotor unit strategies of arthrogenic muscle inhibition are characterised for the first time via decomposed EMG.Motor unit deficits of thigh musculature persist throughout all phases of ACL rehabilitation, even after return-to-sport.After ACL injury, motor unit sizes at similar recruitment thresholds were smaller than those of healthy controls.

The temporal and spatial effects of reconstructive surgery on the atrophy of hindlimb muscles in anterior cruciate ligament transected rats

After anterior cruciate ligament (ACL) injury, a decrease in muscle strength associated with muscle atrophy is frequently observed. The temporal and spatial effects of reconstructive surgery on muscle atrophy have not been examined in detail. This study aimed to 1) reveal the short and mid-term effects of reconstructive surgery on muscle atrophy, and 2) investigate the differences in the degree of atrophy after ACL reconstruction in the hindlimb muscles. ACL transection with or without reconstructive surgery was performed unilaterally on the knees of rats. Untreated rats were used as controls. At one or four weeks post-surgery, the relative muscle wet weights (wet weight/body weight) of the hindlimb muscles were calculated to assess atrophy. At one week post-surgery, muscle atrophy was induced by ACL transection and further aggravated by reconstructive surgery. Reconstructive surgery facilitated recovery from muscle atrophy in some muscles compared with those without reconstructive surgery (ACL transection alone) at four weeks post-surgery. Muscle atrophy after ACL reconstruction was greater in the rectus femoris and plantar flexors than in the semitendinosus and plantar extensors at one week post-surgery. These results indicate that reconstructive surgery exacerbates muscle atrophy in the first week post-surgery, while facilitating recovery between the first and fourth week post-surgery. After reconstructive surgery, muscle atrophy was observed not only in the quadriceps and hamstrings, but also in the lower leg muscles, suggesting the need for muscle strengthening interventions for the lower leg muscles as well as the quadriceps and hamstrings.

The Influence of Hip and Knee Joint Angles on Quadriceps Muscle-Tendon Unit Properties during Maximal Voluntary Isometric Contraction

Determining how the quadriceps femoris musculotendinous unit functions, according to hip and knee joint angles, may help with clinical decisions when prescribing knee extension exercises. We aimed to determine the effect of hip and knee joint angles on structure and neuromuscular functioning of all constituents of the quadriceps femoris and patellar tendon properties. Twenty young males were evaluated in four positions: seated and supine in both 20° and 60° of knee flexion (SIT20, SIT60, SUP20, and SUP60). Peak knee extension torque was determined during maximal voluntary isometric contraction (MVIC). Ultrasound imaging was used at rest and during MVIC to characterize quadriceps femoris muscle and tendon aponeurosis complex stiffness. We found that peak torque and neuromuscular efficiency were higher for SUP60 and SIT60 compared to SUP20 and SIT20 position. We found higher fascicle length and lower pennation angle in positions with the knee flexed at 60°. The tendon aponeurosis complex stiffness, tendon force, stiffness, stress, and Young's modulus seemed greater in more elongated positions (60°) than in shortened positions (20°). In conclusion, clinicians should consider positioning at 60° of knee flexion rather than 20°, regardless if seated or supine, during rehabilitation to load the musculotendinous unit enough to stimulate a cellular response.

Pain inhibition-the unintended benefit of electrically elicited muscle strengthening contractions

BACKGROUND

Neuromuscular electrical stimulation (NMES) is effective in muscle strengthening after orthopedic injury particularly when muscle activation failure is present, but the associated pain can be a barrier. Pain itself can produce a pain inhibitory response called Conditioned Pain Modulation (CPM). CPM is often used in research studies to assess the state of the pain processing system. However, the inhibitory response of CPM could make NMES more tolerable to patients and could improve functional outcomes in people with pain. This study compares the pain-inhibitory effect of NMES compared to volitional contractions and noxious electrical stimulation (NxES).

METHODS

Healthy participants, 18-30 years of age experienced 3 conditions: 10 NMES contractions, 10 bursts of NxES on the patella, and 10 volitional contractions on the right knee. Pressure pain thresholds (PPT) were measured before and after each condition in both knees and the middle finger. Pain was reported on an 11-point VAS. Repeated measures ANOVAs with 2 factors: site and time were performed for each condition followed by post-hoc paired t-tests, with Bonferroni correction.

RESULTS

Pain ratings were higher in the NxES condition compared to NMES (p = .000). No differences in PPTs prior to each condition were observed but PPTs were significantly higher in the right and left knees after the NMES contractions (p = .000, p = .013, respectively) and after the NxES (p = .006, P-.006, respectively). Pain during NMES and NxES did not correlate with pain inhibition (p > .05). Self-reported pain sensitivity correlated with pain during NxES.

CONCLUSION

NxES and NMES produced higher PPTs in both knees but not in the finger, suggesting that the mechanisms responsible for the reduction in pain are located in the spinal cord and local tissues. Pain reduction was elicited during the NxES and NMES conditions regardless of the self-reported pain ratings. When NMES is used for muscle strengthening significant pain reduction can also occur, which is an unintended benefit of the intervention that could improve functional outcomes in patients.

Assessment of the Impact of Physical Activity on the Musculoskeletal System in Early Degenerative Knee Joint Lesions in an Animal Model

Osteoarthritis (OA) is one of the most prevalent diseases of the osteoarticular system. Progressive destruction of joints is accompanied by development of pathological changes in the muscle tissue, i.e., weakening, atrophy, and remodelling (sarcopenia). The aim of the present study is to assess the impact of physical activity on the musculoskeletal system in an animal model of early degenerative lesions in the knee joint. The study involved 30 male Wistar rats. The animals were allocated to three subgroups of 10 animals each. Each animal from the three subgroups received sodium iodoacetate by injection into the patellar ligament of the right knee joint, whereas saline was administered through the patellar ligament in the left knee joint. The rats in the first group were stimulated to exercise on a treadmill. The animals in the second group were allowed to lead a natural lifestyle (no treadmill stimulation). In the third group, all parts of the right hind limb muscle were injected with Clostridium botulinum toxin type A. The study demonstrated that, compared to the active rats, bone density in the immobilised rats decreased, as indicated by the densitometric assessment of the whole body and the examination of rats' hind limbs and knee joints alone. This clearly evidenced the impact of physical activity on bone mineralisation. The weight of both fat and muscle tissues in the physically inactive rats was reduced. Additionally, the adipose tissue had higher weight in the entire right hind limbs, where monoiodoacetic acid was administered to the knee joint. The animal model clearly showed the importance of physical activity in the early stages of OA, as it slows down the process of joint destruction, bone atrophy, and muscle wasting, whereas physical inactivity contributes to progression of generalised changes in the musculoskeletal system.