Utility of Neuromuscular Electrical Stimulation to Preserve Quadriceps Muscle Fiber Size and Contractility After Anterior Cruciate Ligament Injuries and Reconstruction: A Randomized, Sham-Controlled, Blinded Trial

Fostering tissue engineering and regenerative medicine to treat musculoskeletal disorders in bone and muscle

The musculoskeletal system, which is vital for movement, support, and protection, can be impaired by disorders such as osteoporosis, osteoarthritis, and muscular dystrophy. This review focuses on the advances in tissue engineering and regenerative medicine, specifically aimed at alleviating these disorders. It explores the roles of cell therapy, particularly Mesenchymal Stem Cells (MSCs) and Adipose-Derived Stem Cells (ADSCs), biomaterials, and biomolecules/external stimulations in fostering bone and muscle regeneration. The current research underscores the potential of MSCs and ADSCs despite the persistent challenges of cell scarcity, inconsistent outcomes, and safety concerns. Moreover, integrating exogenous materials such as scaffolds and external stimuli like electrical stimulation and growth factors shows promise in enhancing musculoskeletal regeneration. This review emphasizes the need for comprehensive studies and adopting innovative techniques together to refine and advance these multi-therapeutic strategies, ultimately benefiting patients with musculoskeletal disorders.

Quadriceps Activation After Anterior Cruciate Ligament Reconstruction: The Early Bird Gets the Worm!

Arthrogenic Muscle Inhibition (AMI) is a phenomenon observed in individuals with joint injury or pathology, characterized by a reflexive inhibition of surrounding musculature, altered neuromuscular control, and compromised functional performance. After anterior cruciate ligament reconstruction (ACLR) one of the most obvious consequences of AMI is the lack of quadriceps activation and strength. Understanding the underlying mechanisms of AMI is crucial for developing effective therapeutic interventions. The surgical procedure needed to reconstruct the ACL has biochemical et physiological consequences such as inflammation, pain, and altered proprioception. These alterations contribute to the development of AMI. Therapeutic interventions aimed at addressing AMI encompass a multidimensional approach targeting pain reduction, inflammation management, proprioceptive training, and quadriceps activation. Early management focusing on pain modulation through modalities like ice, compression, and pharmacological agents help mitigate the inflammatory response and alleviate pain, thereby reducing the reflexive inhibition of quadriceps. Quadriceps activation techniques such as neuromuscular electrical stimulation (NMES) and biofeedback training aid in overcoming muscle inhibition and restoring muscle strength. NMES elicits muscle contractions through electrical stimulation, bypassing the inhibitory mechanisms associated with AMI, thus facilitating muscle activation and strength gains. Comprehensive rehabilitation programs tailored to individual needs and stage of recovery are essential for optimizing outcomes in AMI. The objective of this clinical viewpoint is to delineate the significance of adopting a multimodal approach for the effective management of AMI, emphasizing the integration of pain modulation, proprioceptive training, muscle activation techniques, and manual therapy interventions. Highlighting the critical role of early intervention and targeted rehabilitation programs, this article aims to underscore their importance in restoring optimal function and mitigating long-term complications associated with AMI.

Effect of muscle length on maximum evoked torque, discomfort, contraction fatigue, and strength adaptations during electrical stimulation in adult populations: A systematic review

Neuromuscular electrical stimulation (NMES) can improve physical function in different populations. NMES-related outcomes may be influenced by muscle length (i.e., joint angle), a modulator of the force generation capacity of muscle fibers. Nevertheless, to date, there is no comprehensive synthesis of the available scientific evidence regarding the optimal joint angle for maximizing the effectiveness of NMES. We performed a systematic review to investigate the effect of muscle length on NMES-induced torque, discomfort, contraction fatigue, and strength training adaptations in healthy and clinical adult populations (PROSPERO: CRD42022332965). We conducted searches across seven electronic databases: PUBMED, Web of Science, EMBASE, PEDro, BIREME, SCIELO, and Cochrane, over the period from June 2022 to October 2023, without restricting the publication year. We included cross-sectional and longitudinal studies that used NMES as an intervention or assessment tool for comparing muscle lengths in adult populations. We excluded studies on vocalization, respiratory, or pelvic floor muscles. Data extraction was performed via a standardized form to gather information on participants, interventions, and outcomes. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for cross-over trials and the Physiotherapy Evidence Database scale. Out of the 1185 articles retrieved through our search strategy, we included 36 studies in our analysis, that included 448 healthy young participants (age: 19-40 years) in order to investigate maximum evoked torque (n = 268), contraction fatigability (n = 87), discomfort (n = 82), and muscle strengthening (n = 22), as well as six participants with spinal cord injuries, and 15 healthy older participants. Meta-analyses were possible for comparing maximal evoked torque according to quadriceps muscle length through knee joint angle. At optimal muscle length 50° - 70° of knee flexion, where 0° is full extension), there was greater evoked torque during nerve stimulation compared to very short (0 - 30°) (p<0.001, CI 95%: -2.03, -1.15 for muscle belly stimulation, and -3.54, -1.16 for femoral nerve stimulation), short (31° - 49°) (p = 0.007, CI 95%: -1.58, -0.25), and long (71° - 90°) (p<0.001, CI 95%: 0.29, 1.02) muscle lengths. At long muscle lengths, NMES evoked greater torque than very short (p<0.001, CI 95%: -2.50, -0.67) and short (p = 0.04, CI 95%: -2.22, -0.06) lengths. The shortest quadriceps length generated the highest perceived discomfort for a given current amplitude. The amount of contraction fatigability was greater when muscle length allowed greater torque generation in the pre-fatigue condition. Strength gains were greater for a protocol at the optimal muscle length than for short muscle length. The quality of evidence was very high for most comparisons for evoked torque. However, further studies are necessary to achieve certainty for the other outcomes. Optimal muscle length should be considered the primary choice during NMES interventions, as it promotes higher levels of force production and may facilitate the preservation/gain in muscle force and mass, with reduced discomfort. However, a longer than optimal muscle length may also be used, due to possible muscle lengthening at high evoked tension. Thorough understanding of these physiological principles is imperative for the appropriate prescription of NMES for healthy and clinical populations.

Acute Compartment Syndrome in a Football Player With Quadriceps Contusion and Successful Return to Sport: A Case Report

CASE

This report describes the case of quadriceps contusion progressing to acute compartment syndrome (ACS) of the thigh. A 17-year-old football player presented the morning after a direct impact injury to the anterior thigh in intractable pain and pain with short arc motion. He was diagnosed with ACS and underwent successful fasciotomy, ultimately returning to play at 4 months.

CONCLUSION

ACS is rare but potential catastrophic progression of quadriceps contusion. Accurate and timely diagnosis followed by appropriate rehabilitation is necessary for optimal outcomes.

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.

Current Evidence-based Approaches to Multimodal Pain Control and Opioid Minimization After Arthroscopic and Knee Preservation Surgery

Nonarthroplasty knee procedures are common and may cause a wide spectrum of postoperative pain, ranging from minimal to severe, depending on the patient, pathology, and procedure. Procedures include ligament repair and reconstruction, especially anterior cruciate ligament reconstruction, meniscal débridement, repair and transplant, periarticular osteotomy, and cartilage restoration. Multimodal analgesia regimens have been implemented successfully, but notable variation characterizes current protocols. Increased public and physician awareness of the burden of opioid usage in the United States has encouraged the medical community to embrace opioid-minimizing and nonopioid techniques to mitigate the deleterious effects of these medications. Nonopioid medications; anesthesia techniques; surgical techniques; and postoperative nonmedication strategies, including physical therapy, transcutaneous electrical nerve stimulation, cryotherapy, cognitive techniques, and non-Western interventions, can form part of an effective multimodal approach. A multimodal approach can facilitate adequate analgesia without compromising patient satisfaction or outcome.

Limb Symmetry Index of Single-Leg Vertical Jump vs. Single-Leg Hop for Distance After ACL Reconstruction: A Systematic Review and Meta-analysis

CONTEXT

The limb symmetry index (LSI) is recommended as a milestone of return to play (RTP), and relying on the LSI value of a single-leg hop for distance (SLHD) test may overestimate rehabilitation status. Identifying a more reliable functional test can help to carefully make decisions for RTP.

OBJECTIVE

The aim was to compare the LSI value of the SLHD test with that of a single-leg vertical jump (SLVJ) test after anterior cruciate ligament reconstruction (ACLR) and determine which test provides lower LSI values.

DATA SOURCES

The PubMed, Web of Science, Embase, and Cochrane Library databases were searched from inception to July 2022.

STUDY SELECTION

Observational studies with participants who had both SLHD and SLVJ tests after ACLR and LSI values of an SLHD and SLVJ were included. Disagreements were resolved after discussion between the 2 researchers.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Data on the primary outcomes (LSI values of the SLVJ and SLHD tests) were collected. Means and standard deviations (SDs) for each variable of interest were used to calculate standardized mean differences (SMDs).

RESULTS

A total of 12 studies met the inclusion criteria for the meta-analysis. A total of 587 patients underwent SLHD and SLVJ tests at different time points after ACLR. Compared with the SLHD test, the SLVJ test provided lower LSI values (SMD -0.42; 95% confidence interval (CI) -0.67 to -0.17). Subgroup analysis found that the SLVJ test provided a lower LSI value than the SLHD test in a specific period (approximately 7-18 months after ACLR, SMD -0.53; 95% CI -0.91 to -0.14) and a similar LSI value at other times.

CONCLUSION

The SLVJ test provided lower LSI values in a specific period (7-18 months after ACLR).

On Putting an End to the Backlash Against Electrophysical Agents

Electrophysical agents (EPAs) are core therapeutic interventions in academic physical therapy curricula around the world. They are used concomitantly with several other therapeutic interventions such as exercise, manual therapy techniques, medications, and surgery for the management of a wide variety of soft tissue disorders. Over the past decade, the practice of EPAs has been the subject of intense scrutiny in the U.S. This has been colored by some physical therapists publicly engaging in bashing rhetoric that has yet to be officially and publicly addressed by the guiding organizations which, together, regulate the practice of physical therapy in this country. Published in world renowned public media are unsubstantiated mocking remarks against the practice of EPAs and unethical allegations against its stakeholders. This rhetoric suggests that EPA interventions are "magical" treatments and that those practitioners who include them in their plans of care may be committing fraud. Such bashing rhetoric is in striking contradiction to the APTA's Guide to Physical Therapist Practice 4.0, which lists EPAs as one of its categories of interventions, the CAPTE's program accreditation policy, and the FSBPT's national licensing exam. The purpose of this commentary is to expose the extent of this discourse and to call to action the APTA, CAPTE, and FSBPT organizations, as well as physical therapists, with the aim at putting an end to this rhetoric.

Decreased rate of torque development in ankle evertors for individuals with chronic ankle instability

BACKGROUND

Individuals with chronic ankle instability have decreased peak torque during maximum voluntary contraction in ankle evertors/invertors, and hip abductors. However, it is unclear whether individuals with chronic ankle instability and/or copers demonstrate decreased rate of torque development in ankle evertors/invertors, and hip abductors.

METHODS

54 university-aged participants (18 chronic ankle instability, 18 copers, and 18 controls) performed three maximal isometric contractions for ankle evertors and invertors, and hip abductors. Rate of torque development was defined as the linear slope of the torque-time curve during the first 200 ms of each contraction and compared between the three groups using a one-way analysis of variance (α = 0.05).

FINDINGS

The chronic ankle instability group showed 38.1% less rate of torque development than the coper (P = 0.03 and d = 0.84) and 37.1% than the control groups (P = 0.03 and d = 1.03) in the ankle evertors. For the hip abductors, there were moderate effects between the chronic ankle instability group and the copers (P = 0.06 and d = 0.70), and control groups (P = 0.06 and d = 0.75).

INTERPRETATIONS

The observed between-groups differences in rate of torque development indicate that restoring rate of torque development after lateral ankle sprain may be important to reduce risk of reinjury and development of chronic ankle instability. Clinicians should consider the rate of torque development in the ankle evertors and hip abductors during rehabilitation chronic ankle instability patients.

Quadriceps Dysfunction Following Joint Preservation Surgery: A Review of the Pathophysiologic Basis and Mitigation Strategies

PURPOSE OF REVIEW

To characterize quadriceps muscle dysfunction associated with knee joint preservation surgery, with a focus on its pathophysiology and promising approaches to mitigate its impact on clinical outcomes.

RECENT FINDINGS

Quadriceps dysfunction (QD) associated with knee joint preservation surgery results from a complex interplay of signaling, related to changes within the joint and from those involving the overlying muscular envelope. Despite intensive rehabilitation regimens, QD may persist for many months postoperatively and negatively impact clinical outcomes associated with various surgical procedures. These facts underscore the need for continued investigation into the potential detrimental effects of regional anesthetic and intraoperative tourniquet use on postoperative quadriceps function, with an outward focus on innovation within the field of postoperative rehabilitation. Neuromuscular stimulation, nutritional supplementation, cryotherapy, blood flow restriction (BFR), and open-chain exercises are all potential additions to postoperative regimens. There is compelling literature to suggest that these modalities are efficacious and may diminish the magnitude and duration of postoperative QD. A clear understanding of QD, with respect to its pathophysiology, should guide perioperative treatment and rehabilitation strategies and influence ongoing rehabilitation-based research and innovation. Moreover, clinicians must appreciate the magnitude of QD's effect on diminished clinical outcomes, risk for re-injury and patients' ability (or inability) to return to pre-injury level of activity following knee joint preservation procedures.

The effect of blood flow restriction training combined with electrical muscle stimulation on neuromuscular adaptation: a randomized controlled trial

Objective: Low-intensity resistance training (≤25% 1RM) combined with blood flow restriction training (BFRT) is beneficial to increasing muscle mass and muscle strength, but it cannot produce increased muscle activation and neuromuscular adaptation, as traditional high-intensity strength training does. The purpose of this study is to investigate the effects of independently applying BFRT and electrical muscle stimulation (EMS), as well as combining the two methods, on muscle function. Methods: Forty healthy participants with irregular exercise experiences were randomly assigned to four groups: BFRT-alone group (BFRT, n = 10), EMS-alone group (EMS, n = 10), BFRT combined with EMS group (CMB, n = 10), and the control group (CTR, n = 10). All participants received low-intensity squat training at a load of 25% 1RM 5 times/week for 6 weeks. Cross-sectional area (CSA) and electromyographic root mean square (RMS) in the rectus femoris, as well as peak torque (PT) of the knee extensor, were measured before and following a 6-week intervention. Results: Following the 6-week intervention, the increases in muscle activation in the CMB group were statistically higher than those in the BFRT group (p < 0.001), but not different from those in the EMS group (p = 0.986). Conclusion: These data suggest that the combination of BFRT and EMS for low-intensity squat training improved the muscle strength of the lower limbs by promoting muscle hypertrophy and improving muscle activation, likely because such a combination compensates for the limitations and deficiencies of the two intervention methods when applied alone.

Neuromuscular electrical stimulation preserves muscle strength early after total knee arthroplasty: Effects on muscle fiber size

Loss of quadriceps strength after total knee arthroplasty (TKA) is most pronounced acutely but persists long-term, negatively impacting physical function in daily activities. Neuromuscular electrical stimulation (NMES) early after surgery is an effective adjuvant to standard of care rehabilitation (SOC) for attenuating strength loss following TKA, but the mechanisms whereby NMES maintains strength are unclear. This work aimed to determine the effects of early NMES on quadriceps strength and skeletal muscle fiber size 2 weeks after TKA compared to SOC. Patients scheduled for primary, unilateral TKA were enrolled and randomized into SOC (n = 9) or NMES plus SOC (n = 10) groups. NMES was started within 48 h of TKA, with 45-min sessions twice a day for 2 weeks. Isometric quadriceps strength was assessed preoperatively and 2 weeks following TKA. Vastus lateralis muscle biopsies of the involved leg were performed at the same time points and immunohistochemistry conducted to assess muscle fiber cross-sectional area and distinguish fiber types. Groups did not differ in age, body mass index, sex distribution, or preoperative strength. Both groups got weaker postoperatively, but the NMES group had higher normalized strength. After 2 weeks, the group receiving NMES and SOC had significantly greater MHC IIA and MHC IIA/IIX fiber size compared to SOC alone, with no group differences in MHC I fiber size. These results suggest that NMES mitigates early muscle weakness following TKA, in part, via effects on fast-twitch, type II muscle fiber size. This investigation advances our understanding of how adjuvant, early postoperative NMES aids muscle strength recovery.

There Is Substantial Variation in Rehabilitation Protocols Following Anterior Cruciate Ligament Reconstruction: A Survey of 46 American Orthopaedic Surgeons

PURPOSE

To identify the clinical practice preferences of orthopaedic surgeons regarding anterior cruciate ligament reconstruction (ACLR) rehabilitation through a survey of members of the Arthroscopy Association of North American (AANA) and the American Orthopaedic Society for Sports Medicine (AOSSM).

METHODS

An online survey was distributed to members of AANA and AOSSM between November 2020 and September 2021. Participants reported on their clinical preferences for ACLR protocol development and patient selection, use of technology in ACLR recovery and rehabilitation, and preferences for advancing through multiple phases of the rehabilitative process.

RESULTS

Responses from 46 orthopaedic surgeons were analyzed. Patient-reported outcome measures were not found to be utilized often at various phases of the perioperative period. Thirty-eight (82.6%) participants reported utilization of postoperative bracing. There was no consensus on when participants allow their patients to advance through rehabilitation, but most report waiting 3 to 4 months for advancement to jogging/lateral movement, 6 to 8 months for return to noncontact sport, and 9 months of more for return to unrestricted sport. Many participants utilize functional and strength testing with associated limb symmetry indices to determine patient readiness to return to sport, with 18, 26, and 25 participants reporting use of functional testing and 28, 26, and 27 participants reporting use of strength testing at the return to jogging/lateral movements, noncontact return to sport, and unrestricted return-to-sport phases, respectively.

CONCLUSIONS

This study provides an insight into the rehabilitative protocols and modalities utilized for ACLR by orthopaedic surgeons in practice across the United States. There is notably substantial variation in rehabilitative patterns and preferences, particularly with regards to what constitutes criteria for progressing patients through the phases of returning to unrestricted sport. Additionally, our findings show that while many surgeons believe that quantitative assessment technology could be beneficial in decision-making for returning patients to sport, there are still many barriers that stand in the way of its implementation into clinical practice.

CLINICAL RELEVANCE

Postoperative rehabilitative protocols after ACLR vary by surgeon.

Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction

This guideline was developed to inform clinical practice on rehabilitation after anterior cruciate ligament reconstruction (ACLR) and was performed in accordance with the Appraisal of Guidelines for REsearch & Evaluation II (AGREE II) instrument and used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. A Guideline Development Group systematically searched and reviewed evidence using randomised clinical trials and systematic reviews to evaluate the effectiveness of rehabilitation interventions and guide clinicians and patients on the content of the optimal rehabilitation protocol after ACLR.The guideline targets patients during rehabilitation after ACLR and investigates the effectiveness of the available interventions to the physiotherapist, alone or in combination (eg, exercise, modalities, objective progression criteria). Exercise interventions should be considered the mainstay of ACLR rehabilitation. However, there is little evidence on the dose-response relationship between volume and/or intensity of exercise and outcomes. Physical therapy modalities can be helpful as an adjunct in the early phase of rehabilitation when pain, swelling and limitations in range of motion are present. Adding modalities in the early phase may allow earlier pain-free commencement of exercise rehabilitation. Return to running and return to training/activity are key milestones for rehabilitation after ACLR. However, there is no evidence on which progression or discharge criteria should be used.While there is a very low level of certainty for most components of rehabilitation, most of the recommendations provided in this guideline were agreed to by expert clinicians. This guideline also highlights several new elements of ACLR management not reported previously.

Depressed Protein Synthesis and Anabolic Signaling Potentiate ACL Tear-Resultant Quadriceps Atrophy

BACKGROUND

Anterior cruciate ligament (ACL) tear (ACLT) leads to protracted quadriceps muscle atrophy. Protein turnover largely dictates muscle size and is highly responsive to injury and loading. Regulation of quadriceps molecular protein synthetic machinery after ACLT has largely been unexplored, limiting development of targeted therapies.

PURPOSE

To define the effect of ACLT on (1) the activation of protein synthetic and catabolic signaling within quadriceps biopsy specimens from human participants and (2) the time course of alterations to protein synthesis and its molecular regulation in a mouse ACL injury model.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Muscle biopsy specimens were obtained from the ACL-injured and noninjured vastus lateralis of young adult humans after an overnight fast (N = 21; mean ± SD, 19 ± 5 years). Mice had their limbs assigned to ACLT or control, and whole quadriceps were collected 6 hours or 1, 3, or 7 days after injury with puromycin injected before tissue collection for assessment of relative protein synthesis. Muscle fiber size and expression and phosphorylation of protein anabolic and catabolic signaling proteins were assessed at the protein and transcript levels (RNA sequencing).

RESULTS

Human quadriceps showed reduced phosphorylation of ribosomal protein S6 (-41%) in the ACL-injured limb (P = .008), in addition to elevated phosphorylation of eukaryotic initiation factor 2α (+98%; P = .006), indicative of depressed protein anabolic signaling in the injured limb. No differences in E3 ubiquitin ligase expression were noted. Protein synthesis was lower at 1 day (P = .01 vs control limb) and 3 days (P = .002 vs control limb) after ACLT in mice. Pathway analyses revealed shared molecular alterations between human and mouse quadriceps after ACLT.

CONCLUSION

(1) Global protein synthesis and anabolic signaling deficits occur in the quadriceps in response to ACL injury, without notable changes in measured markers of muscle protein catabolism. (2) Importantly, these deficits occur before the onset of significant atrophy, underscoring the need for early intervention.

CLINICAL RELEVANCE

These findings suggest that blunted protein anabolism as opposed to increased catabolism likely mediates quadriceps atrophy after ACL injury. Thus, future interventions should aim to restore muscle protein anabolism rapidly after ACLT.

Electrical stimulation therapy for peripheral nerve injury

Peripheral nerve injury is common and frequently occurs in extremity trauma patients. The motor and sensory impairment caused by the injury will affect patients' daily life and social work. Surgical therapeutic approaches don't assure functional recovery, which may lead to neuronal atrophy and hinder accelerated regeneration. Rehabilitation is a necessary stage for patients to recover better. A meaningful role in non-pharmacological intervention is played by rehabilitation, through individualized electrical stimulation therapy. Clinical studies have shown that electrical stimulation enhances axon growth during nerve repair and accelerates sensorimotor recovery. According to different effects and parameters, electrical stimulation can be divided into neuromuscular, transcutaneous, and functional electrical stimulation. The therapeutic mechanism of electrical stimulation may be to reduce muscle atrophy and promote muscle reinnervation by increasing the expression of structural protective proteins and neurotrophic factors. Meanwhile, it can modulate sensory feedback and reduce neuralgia by inhibiting the descending pathway. However, there are not many summary clinical application parameters of electrical stimulation, and the long-term effectiveness and safety also need to be further explored. This article aims to explore application methodologies for effective electrical stimulation in the rehabilitation of peripheral nerve injury, with simultaneous consideration for fundamental principles of electrical stimulation and the latest technology. The highlight of this paper is to identify the most appropriate stimulation parameters (frequency, intensity, duration) to achieve efficacious electrical stimulation in the rehabilitation of peripheral nerve injury.

Physiological effects of microcurrent and its application for maximising acute responses and chronic adaptations to exercise

Microcurrent is a non-invasive and safe electrotherapy applied through a series of sub-sensory electrical currents (less than 1 mA), which are of a similar magnitude to the currents generated endogenously by the human body. This review focuses on examining the physiological mechanisms mediating the effects of microcurrent when combined with different exercise modalities (e.g. endurance and strength) in healthy physically active individuals. The reviewed literature suggests the following candidate mechanisms could be involved in enhancing the effects of exercise when combined with microcurrent: (i) increased adenosine triphosphate resynthesis, (ii) maintenance of intercellular calcium homeostasis that in turn optimises exercise-induced structural and morphological adaptations, (iii) eliciting a hormone-like effect, which increases catecholamine secretion that in turn enhances exercise-induced lipolysis and (iv) enhanced muscle protein synthesis. In healthy individuals, despite a lack of standardisation on how microcurrent is combined with exercise (e.g. whether the microcurrent is pulsed or continuous), there is evidence concerning its effects in promoting body fat reduction, skeletal muscle remodelling and growth as well as attenuating delayed-onset muscle soreness. The greatest hindrance to understanding the combined effects of microcurrent and exercise is the variability of the implemented protocols, which adds further challenges to identifying the mechanisms, optimal patterns of current(s) and methodology of application. Future studies should standardise microcurrent protocols by accurately describing the used current [e.g. intensity (μA), frequency (Hz), application time (minutes) and treatment duration (e.g. weeks)] for specific exercise outcomes, e.g. strength and power, endurance, and gaining muscle mass or reducing body fat.

Rehabilitation And Advances In Surgical Reconstruction For Anterior Cruciate Ligament Insufficiency: What Has Changed Since The 1960s? - State Of The Art

Anterior cruciate ligament (ACL) insufficiency can be disabling, given the physical and sports activity constraints that negatively impact the quality of life. Consequently, surgery is the main approach for most active patients. Nonetheless, ACL reconstruction (ACLR) cannot be successful without adequate preoperative and postoperative rehabilitation. Since the 1960s, post-ACLR rehabilitation has evolved, mainly from advances in surgery, coupled with a better understanding of the biological concepts of graft revascularization, maturation and integration, which have impacted ACL postoperative rehabilitation protocols. However, new technologies do involve a definite learning curve which could affect rehabilitation programs and produce inconsistent results. The development of rehabilitation protocols cannot be defined without an accurate diagnosis of ACL injury and considering the patient's main physical demands and expectations. This article discusses how postoperative rehabilitation following ACLR has changed from the 1960s to now, focussing on surgical technique (type of tendon graft, fixation devices, and graft tensioning), biological concepts (graft maturation and integration), rehabilitation protocols (prevention of ACL injuries, preoperative rehabilitation, postoperative rehabilitation), criteria to return to sports, patient's reported outcomes and outcome. Although rehabilitation plays an essential role in managing ACL injuries, it cannot be fully standardised preoperatively or postoperatively. Preoperative and postoperative rehabilitation should be based on an accurate clinical diagnosis, patients' understanding of their injury, graft tissue biology and biomechanics, surgical technique, the patient's physical demands and expectations, geographical differences in ACL rehabilitation and future perspectives.

The Duration of Thigh Tourniquet Use Associated With Anterior Cruciate Ligament Reconstruction Does Not Produce Cellular-Level Contractile Dysfunction of the Quadriceps Muscle at 3 Weeks After Surgery

BACKGROUND

Anterior cruciate ligament (ACL) trauma and ACL reconstruction (ACLR) are associated with the loss of strength and function of the muscles that span the knee joint. The underlying mechanism associated with this is not completely understood.

PURPOSE

To determine whether the duration of tourniquet use during ACLR has an effect on knee extensor muscle contractile function and size at the cellular (ie, fiber) level 3 weeks after surgery and at the whole-muscle level at 6 months after surgery.

STUDY DESIGN

Descriptive laboratory study and case series; Level of evidence, 4.

METHODS

Study participants sustained an acute, first-time ACL injury. All participants underwent ACLR with the use of a tourniquet placed in a standardized location on the thigh; the tourniquet was inflated (pressure range, 250-275 mm Hg), and the time of tourniquet use during surgery was documented. Participants were evaluated 1 week before surgery (to measure patient function, strength, and subjective outcome with the Knee injury and Osteoarthritis Outcome Score [KOOS] and International Knee Documentation Committee [IKDC] score), at 3 weeks after ACLR surgery (to obtain muscle biopsy specimens of the vastus lateralis and assess muscle fiber cross-sectional area, contractile function, and mitochondrial content and morphometry), and at 6 months after ACLR (to evaluate patient function, strength, and subjective outcomes via KOOS and IKDC scores). Data were acquired on both the injured/surgical limb and the contralateral, normal side to facilitate the use of a within-subjects study design. Results are based on additional analysis of data acquired from previous research that had common entry criteria, treatments, and follow-up protocols.

RESULTS

At 3 weeks after ACLR, the duration of tourniquet use at the time of surgery did not explain the variation in single-muscle fiber contractile function or cross-sectional area (myosin heavy chain [MHC] I and II fibers) or subsarcolemmal and intermyofibrillar mitochondrial content or morphometry. At 6 months after ACLR, the duration of tourniquet use was not associated with the peak isometric and isokinetic torque measurements, patient function, or patient-reported outcomes.

CONCLUSION

The duration of tourniquet use at the time of ACLR surgery did not explain variation in muscle fiber size, contractile function, or mitochondrial content at 3 weeks after surgery or strength of the quadriceps musculature or patient-reported function or quality of life at 6-month follow-up.

Return to sports after ACL injury 5 years from now: 10 things we must do

Background

The outcome after ACL reconstruction (ACLR) is in general disappointing with unacceptable number of athletes that do not return to pre-injury level of sports, high re-injury rates, early development of osteoarthritis and shorter careers. Athletes after ACLR have high expectation to return to sports which is in contrast with the current outcomes. The aim of this manuscript is to present an overview of factors that are needed to be incorporated and to personalize the rehabilitation process for an athlete who has undergone an ACLR.

Level of evidence

4.

Effects of neuromuscular electrical muscle stimulation on the deltoid for shoulder function restoration after reverse total shoulder arthroplasty in the early recovery period: a prospective randomized study

INTRODUCTION

Neuromuscular electrical stimulation (NMES) is a treatment modality that has been used to accelerate the rehabilitation of patients with neurological damage. However, it is unclear whether NMES of the deltoid can lead to the early restoration of shoulder function after reverse total shoulder arthroplasty (RSA).

MATERIALS AND METHODS

In this prospective and randomized study, 88 patients who underwent RSA with the same prosthesis design for cuff tear arthropathy or irreparable rotator cuff tear were assessed. The patients were divided into two groups (NMES group and non-NMES group, 44 patients each). For the NMES group, two pads of the NMES device were placed over the middle and posterior deltoid area, and NMES was maintained for 1 month after surgery. Shoulder functional outcomes and deltoid thickness were compared at 3, 6, and 12 months postoperatively. Shoulder functional outcomes were assessed based on the visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES), and Constant scores and the range of motion (ROM) and power of the affected shoulder. The thickness of the anterior, middle, and posterior deltoid was measured by ultrasonography.

RESULTS

A total of 76 patients (NMES group, 33 patients; non-NMES group, 43 patients) were enrolled in the final analysis. The preoperative demographics and status of the remaining rotator cuff of both groups were not significantly different. At postoperative 3 months, the ROM and power of external rotation of the NMES group were significantly greater than those of the non-NMES group (ROM, 36° ± 14° vs. 29° ± 12°; P = .003; power, 4.8 kg ± 1.8 kg vs. 3.8 kg ± 1.0 kg; P < .002). The ROM of external rotation of the NMES group at postoperative 6 months was also greater than that of the non-NMES group (41° ± 12° vs. 34° ± 11°; P = .013). However, there was no significant difference in the VAS, ASES, and Constant scores at all follow-up points despite gradual improvements until 1 year postoperatively. Serial measurements of the thickness of the anterior, middle, and posterior deltoid of both groups did not show significant differences.

CONCLUSIONS

Postoperative NMES of the deltoid after RSA contributed to significantly faster ROM restoration and considerable improvement in the power of external rotation. Therefore, NMES following RSA could lead to the early restoration of external rotation and recovery of deltoid function.

Low-frequency electrical stimulation alleviates immobilization-evoked disuse muscle atrophy by repressing autophagy in skeletal muscle of rabbits

BACKGROUND

The study aimed to investigate the effect of low-frequency electrical stimulation (LFES) on disuse muscle atrophy and its mechanism in a rabbit model of knee extension contracture.

METHODS

This study involved two experiments. In the time-point experiment, 24 rabbits were randomly divided into 4 groups: Control 1 (Ctrl1 group), immobilization for 2 weeks (I-2 group), immobilization for 4 weeks (I-4 group), and immobilization for 6 weeks (I-6 group). In the intervention experiment, 24 rabbits were randomly divided into 4 groups: Control 2 (Ctrl2 group), electrical stimulation (ESG group), natural recovery (NRG group), and electrical stimulation treatment (ESTG group). All intervention effects were assessed by evaluating the knee joint range of motion (ROM), cross-sectional area (CSA) of the rectus femoris muscle, and expression of autophagy-related proteins.

RESULTS

The time-point experiment showed that immobilization reduced the knee ROM, reduced the rectus femoris muscle CSA, and activated autophagy in skeletal muscle. The levels of five autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), autophagy-related protein 7 (Atg7), p62, and microtubule-associated protein light chain 3B-II (LC3B-II)] were significantly elevated in the skeletal muscle of the I-4 group. The intervention experiment further showed that LFES significantly improved the immobilization-induced reductions in ROM and CSA. Additionally, LFES resulted in a significant decrease in the protein expression of mTOR, p-mTOR, Atg7, p62, and LC3B-II in the rectus femoris muscle.

CONCLUSIONS

LFES alleviates immobilization-evoked disuse muscle atrophy possibly by inhibiting autophagy in the skeletal muscle of rabbits.

Anterior Cruciate Ligament Reconstruction Recovery and Rehabilitation: A Systematic Review

BACKGROUND

The success of anterior cruciate ligament (ACL) reconstruction is influenced by effective rehabilitation. Previously published, comprehensive systematic reviews evaluating rehabilitation after ACL reconstruction have studied Level-I and II evidence published through 2012. Interval studies continue to evaluate the efficacy of various rehabilitative modalities.

METHODS

A total of 824 articles from 2012 to 2020 were identified using multiple search engines. Fifty Level-I or II studies met inclusion criteria and were evaluated using the Consolidated Standards of Reporting Trials (CONSORT) criteria and National Institutes of Health (NIH) Study Quality Assessment Tools.

RESULTS

Accelerated rehabilitation can be effective for patients with semitendinosus-gracilis grafts. Blood flow restriction (BFR) training with high-intensity exercise is not effective for ACL reconstruction recovery. Postoperative bracing does not offer any advantages or improve limb asymmetry. Cryotherapy is an effective analgesic when used perioperatively. The early introduction of open kinetic chain exercises may improve ACL reconstruction outcomes, and high-intensity plyometric exercise is not effective. Estimated pre-injury capacity (EPIC) levels may be more accurate than the Limb Symmetry Index (LSI) when using functional test results to predict reinjury rates, and hip external rotation strength may be the most accurate predictor of the hop test performance. Nerve blocks can provide postoperative analgesia with minimal complication risk. Neuromuscular electrical stimulation is effective when used independently and in combination with rehabilitative exercises. Psychological readiness should be evaluated both objectively and subjectively before allowing patients to safely return to sport. Electromyography biofeedback may help to regain muscular function, and whole-body vibration therapy can improve postural control. Supervised rehabilitation is more effective than unsupervised rehabilitation.

CONCLUSIONS

Various rehabilitative modalities following ACL reconstruction are effective in improving surgical outcomes and return-to-sport rates. Further evidence and improved study design are needed to further validate modalities including accelerated rehabilitation, BFR training, functional testing, and return-to-sport criteria.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Use of Neuromuscular Electrical Stimulation for Abdominal and Quadriceps Muscle Strengthening: A Randomized Controlled Trial

BACKGROUND

Radiographic imaging has demonstrated muscle hypertrophy after treatment with noninvasive body contouring devices that target skeletal muscles.

OBJECTIVE

This pilot study sought to evaluate whether increased muscle mass translated to improved functional strength and endurance.

METHODS

A prospective, single-center, randomized open-label controlled study included 26 subjects randomized into 3 groups: 2 treatment groups and 1 control group. Both treatment groups received 4 neuromuscular electrical stimulation (NMES) treatments over a 2-week period. Muscle performance testing was conducted at baseline and 2-week and 4-week posttreatment. Anthropometric measurements were assessed at baseline and at 4-week posttreatment. Study participants completed subject satisfaction surveys and a personal experience assessment.

RESULTS

Treatment with NMES resulted in statistically significant improvements in abdominal and quadriceps strength and endurance from baseline through 4-week posttreatment. Mean waist circumference decreased and quadriceps circumference increased, both nonsignificantly. Subject satisfaction regarding abdominal and quadriceps strength was reported as "satisfied or very satisfied" in 89% and 92% at 4-week and 8-week posttreatment, respectively.

CONCLUSION

Treatment of the abdomen and quadriceps with NMES leads to significant improvements in muscular strength and endurance.

Skeletal muscle cellular contractile dysfunction after anterior cruciate ligament reconstruction contributes to quadriceps weakness at 6-month follow-up

Muscle dysfunction following anterior cruciate ligament reconstruction (ACLR) may evolve from alterations in muscle contractility at the myofilament protein level. Using a prospective, within-subject case-control design, we evaluated cellular-level contractility, cross-sectional area (CSA), and myosin heavy chain (MHC) isoform expression on single muscle fibers 3 weeks post ACLR, and evaluated their relationship to whole muscle strength and patient-oriented outcomes 6 months post operation. Biopsies of the vastus lateralis were performed 3 weeks post ACLR in 11 subjects (5 females, mean age ± SD = 24.7 ± 6.5 years, height = 172.7 ± 8.2 cm, mass = 75.7 ± 12.5 kg) following first-time ACL rupture and whole muscle strength and self-reported pain, function, and quality of life assessed 6 months post ACLR. At 3 weeks post ACLR, force production was reduced (p < 0.01) in MHC I (-36%) and IIA (-48%) fibers compared with the non-injured leg. When force production was expressed relative to CSA to account for fiber atrophy, reductions remained in MHC IIA fibers (-40%; p < 0.001), but MHC I fibers showed only a trend toward being lower (-13%; p = 0.09). Finally, skeletal muscle fiber functional deficits at 3 weeks post ACLR were associated with whole muscle weakness and less favorable patient-reported outcomes at 6-month follow-up. Thus, ACLR promotes early cellular contractile dysfunction that may contribute to decreased whole muscle strength and patient function, and increased patient-reported symptoms, at 6-month follow-up.

Acute Effects of 3 Neuromuscular Electrical Stimulation Waveforms on Exercising and Recovery Microvascular Oxygenation Responses

CONTEXT

When emphasizing muscular strength during postoperative rehabilitation it is recommended to use a neuromuscular electrical stimulation (NMES) waveform that elicits the greatest muscle force and local metabolic demand that is also well tolerated. The present investigation examined the effects that 3 different clinically used NMES waveforms had on the electrically elicited force (EEF), local metabolic demand (exercising muscle oxygen saturation [SmO2]), and the subsequent reactive hyperemia response (recovery total hemoglobin concentration [THb]) of the knee extensors.

DESIGN

Single session repeated-measures design.

METHODS

EEF, local metabolic demand, and reactive hyperemia responses were measured during and subsequent to 3 NMES waveforms: Russian burst modulated alternating current (RUS), biphasic pulsed current (VMS™), and burst modulated biphasic pulsed current (VMS-Burst™). Exercising SmO2 and recovery THb were assessed noninvasively using a near-infrared spectroscopy sensor placed on the vastus lateralis. Participants completed one set of 10 repetitions of each NMES waveform and were provided with 5 minutes of passive, interset recovery. Two-way, repeated-measures analysis of variance examined if NMES waveform or repetition significantly affected (P < .05) EEF or exercising SmO2. Two-way, repeated-measures analysis of variance examined if NMES waveform or recovery time affected recovery THb.

RESULTS

VMS™ and VMS-Burst™ yielded higher EEF (F = 11.839, P < .001) and greater local metabolic stress (lower exercising SmO2, F = 13.654, P < .001) compared with RUS. Greater rate of EEF decline throughout the NMES set was observed during RUS (%Δ = -50 [6] %Rep1) compared with VMS-Burst™ (%Δ = -30 [7] %Rep1) and VMS™ (%Δ = -32 [7] %Rep1). VMS™ elicited a higher reactive hyperemia response (higher recovery THb) compared with RUS (F = 3.427, P = .048).

CONCLUSIONS

The present findings support the use of VMS™ or VMS-Burst™ compared with RUS when promoting muscular strength. In addition, the use of VMS™ might provide a greater blood volume to the target muscle subsequent to NMES contractions compared with RUS.

Contemporary Principles for Postoperative Rehabilitation and Return to Sport for Athletes Undergoing Anterior Cruciate Ligament Reconstruction

Despite advancements in our understanding of anterior cruciate ligament (ACL) injury prevention and nonsurgical management, ACL reconstruction continues to occur at an alarming rate. Among athletic patients, individuals participating in basketball, soccer, and football have the highest incidence of ACL injury, often requiring surgical intervention. To ensure the optimal treatment strategy for return to sport and prevention of secondary graft re-tear, it is important to tailor to the specific demands of the injured athlete and apply evidence-based best practices and rehabilitation principles. The purpose of this review is to provide readers with a brief background regarding ACL injuries, a focused review of clinical outcome studies after ACL reconstruction, and an updated framework with expert-guided recommendations for postoperative rehabilitation and return to sporting activity. Currently, there is no gold standard for rehabilitation after ACL reconstruction, highlighting the need for robust studies evaluating the best modalities for athlete rehabilitation, as well as determining the efficacy of new tools for improving therapy including blood flow restriction therapy and neuromuscular electrical stimulation. Based on clinical experience, a renewed focus on objective, criteria-based milestones may maximize the ability of return to preinjury levels of athletic function.

Postoperative Rehabilitation and Return to Sport Following Multiligament Knee Reconstruction

Multiligament knee injuries (MLKIs) are debilitating injuries that increasingly occur in young athletes. Return to sport (RTS) has historically been considered unlikely due to the severity of these injuries. Reporting in the literature regarding objective outcomes following MLKI, including RTS, is lacking, as are clear protocols for both rehabilitation progressions and RTS testing. RTS following MLKI is a complex process that requires an extended recovery duration compared to other surgery types. Progressions through postoperative rehabilitation and RTS should be thoughtful, gradual, and criterion based. After effective anatomic reconstruction to restore joint stability, objective measures of recovery including range of motion, strength, movement quality, power, and overall conditioning guide decision-making throughout the recovery process. It is important to frame the recovery process of the athlete in the context of the severity of their injury, as it is typically slower and less linear. Improved reporting on objective outcomes will enhance our understanding of recovery expectations within this population by highlighting persistent deficits that may interfere with a full recovery, including RTS.

Multiple Ligament Reconstructions of the Knee and Posterolateral Corner

Injuries to the knee involving multiple ligaments occur in a variety of circumstances and require careful assessment and planning. A wide constellation of injuries can occur with causes sufficiently traumatic to produce bicruciate ligament deficiency, and this technical report will describe diagnosis, treatment and rehabilitation for a knee dislocation with lateral injury (KD-III-L on the Schenk classification). Reconstruction in the acute setting is preferred, with anatomic-based, single-bundle anterior cruciate ligament reconstruction, double-bundle posterior cruciate ligament reconstruction, and anatomic reconstruction of the posterolateral corner using two grafts for the 3 primary posterolateral corner stabilizers. Tunnel orientation to prevent convergence and sequence of graft tensioning and fixation are discussed as well. Successful outcomes have been achieved using these anatomic-based reconstruction techniques along with appropriate rehabilitation and bracing.