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.

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.

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.

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.

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.

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.

Exercise-induced fatigue affects knee proprioceptive acuity and quadriceps neuromuscular function more in patients with ACL reconstruction or meniscus surgery than in healthy individuals.

PURPOSE: To observe how knee proprioceptive acuity and quadriceps neuromuscular function change during and after repeated isokinetic knee-extension exercise in patients with anterior cruciate ligament reconstruction (ACLR) or meniscus surgery. METHODS: Patients with ACLR or meniscus surgery and matched controls (n = 19 in each group) performed knee-flexion replication at 15° and 75°, and quadriceps peak torque (PT), central activation ratio (CAR) and rate of torque development (RTD) at baseline and immediately after every five sets of isokinetic knee-extension exercise (times 1-5). RESULTS: Compared to the baseline, the ACLR and control groups displayed errors in knee-flexion replication at 75° only at time 5 (115.9-155.6%; p ≤ 0.04, d ≥ 0.97), whereas the meniscus surgery group exhibited errors at all time points (142.5-265.6%; p ≤ 0.0003, d ≥ 1.4). Significant percentage reductions in quadriceps CAR were observed between times 4 and 5 in the ACLR group (-5.8%; p = 0.0002, d = 0.96), but not in the meniscus surgery (-1.4%; n.s.) and control (0.1%; n.s.) groups. Significant percentage reductions in quadriceps RTD were observed between times 4 and 5 in the ACLR (-24.2%; p = 0.007, d = 0.99) and meniscus surgery (-23.0%; p = 0.01, d = 0.85) groups, but not in the control group (-0.2%; n.s.). CONCLUSION: Patients with ACLR or meniscus surgery displayed a greater loss in knee proprioceptive acuity and quadriceps neuromuscular function during and after exercise than healthy individuals. Evidence-based interventions to enhance exercise-induced fatigue resistance should be implemented following ACLR or meniscus surgery, aiming to prevent proprioceptive and neuromuscular changes within the knee joint and quadriceps. LEVEL OF EVIDENCE: III.

Dry Needling for Arthrogenic Muscle Inhibition of Quadriceps Femoris in Patients after Reconstruction of Anterior Cruciate Ligament: a Protocol for a Randomized Controlled Trial.

Background: : Dry needling (DN) is recommended as a therapeutic modality for various neuromusculoskeletal disorders. No study has been performed on the impact of DN on arthrogenic muscle inhibition (AMI) after anterior cruciate ligament reconstruction (ACLR). This study protocol is aimed to investigate the impacts of DN on AMI of quadriceps femoris, corticomotor, and spinal reflex excitability in patients with ACLR. Methods: : A double-blind, between-subject, randomized, controlled trial will be conducted to measure changes in AMI after DN. Twenty-four subjects with ACLR will be recruited to receive a DN or a sham DN, providing that they met the inclusion criteria. Three sessions of DN on the quadriceps femoris will be applied during a one-week period. The primary outcome measures are the active motor threshold, motor evoked potential, and Hmax - Mmax ratio. The secondary outcomes are the International Knee Documentation Committee subjective knee form questionnaire score and maximum quadriceps isometric torque. Data will be collected at baseline, immediately after the first session, after the third session, and at the one-month follow-up visit. Discussion: : The results of this study will provide preliminary evidence regarding the effects of DN on AMI of quadriceps femoris in patients with ACLR.

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.

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.

Hamstrings fatigue does not improve quadriceps function in individuals with anterior cruciate ligament reconstruction.

OBJECTIVES: Our purpose was to investigate the immediate and prolonged effects of hamstrings fatigue on quadriceps neuromuscular function in individuals with anterior cruciate ligament reconstruction (ACLR) and matched uninjured controls. DESIGN: Cross-Sectional. SETTING: Laboratory. PARTICIPANTS: 16 participants with a history of ACLR and 16 uninjured controls. MAIN OUTCOME MEASURES: Quadriceps peak torque (PT), central activation ratio (CAR), early (RTD100) and late (RTD200) rate of torque development, vastus medialis and lateralis electromyographic (EMG) activity, and hamstrings-to-quadriceps co-activation assessed at baseline. Outcomes were evaluated pre-fatigue (PRE), immediately post-fatigue (POST), and 30min post-fatigue (POST30). The involved limbs of individuals with ACLR were assessed and control limbs were matched based on limb dominance. RESULTS: Individuals with ACLR demonstrated lesser quadriceps PT (p = 0.004), CAR (p < 0.001), RTD100 (p = 0.042), RTD200 (p = 0.028), and vastus medialis EMG (p = 0.040) than controls, regardless of time. Quadriceps CAR (p < 0.001) and RTD200 (p < 0.001) decreased at POST and POST30, whereas RTD100 (p < 0.001) decreased at POST, regardless of group. CONCLUSIONS: The observed reductions in quadriceps neuromuscular function may suggest involvement of central fatigue mechanisms, which should be explored prior to recommending hamstrings fatigue as a therapeutic intervention.

Spinal Reflex Excitability of Lower Leg Muscles Following Acute Lateral Ankle Sprain: Bilateral Inhibition of Soleus Spinal Reflex Excitability.

Neural changes in the ankle stabilizing muscles following ankle sprains are thought to be one contributing factor to persistent ankle dysfunction. However, empirical evidence is limited. Therefore, we aimed to examine spinal reflex excitability of lower leg muscles following acute ankle sprains (AAS). We performed a case-control study with 2 groups consisting of 30 young adults with AAS and 30 aged-matched uninjured controls. Hoffmann reflex (H-reflex) testing was performed to estimate spinal reflex excitability of lower leg muscles: soleus, fibularis longus (FL), tibialis anterior (TA). Maximal H-reflex (Hmax) and motor responses (Mmax) were determined by delivering a series of electrical stimuli at the sciatic nerve. Hmax/Mmax ratios were calculated to represent normalized spinal reflex excitability. Separate group-by-limb analyses of variance (ANOVA) with repeated measures found there were no significant interactions for any of the muscles (SL: F1,56 = 0.95, p = 0.33, FL: F1,51 = 0.65, p = 0.42, TA: F1,51 = 1.87, p = 0.18), but there was a significant main effect of group in the soleus (F1,56 = 6.56, p = 0.013), indicating the Hmax/Mmax ratio of soleus in the AAS group was significantly lower bilaterally (AAS = 0.56 ± 0.19, control = 0.68 ± 0.17, p = 0.013), with no significant group differences in the other muscles (FL: F1,51 = 0.26, p = 0.61, TA: F1,51 = 0.93, p = 0.34). The bilateral inhibition of the soleus spinal reflex excitability following AAS may be significant in that it may explain bilateral sensorimotor deficits (postural control deficits) following unilateral injury, and provide insights into additional therapies aimed at the neural change.

Steadiness training improves the quadriceps strength and self-reported outcomes in persistent quadriceps weakness following nine months of anterior cruciate ligament reconstruction and failed conventional physiotherapy.

Background Persistent quadriceps weakness may occur after anterior cruciate ligament reconstruction, limiting the strength gain. However, steadiness strengthening might change the inability to gain strength. Hence, we determined whether strength training with force steadiness and visual biofeedback can improve knee quadriceps torque, self-reported pain and knee stability in patients with persistent quadriceps weakness after knee anterior cruciate ligament reconstruction. Methods Twenty-five patients (aged 43.7 ± 12.2 years) with persistent quadriceps weakness following knee anterior cruciate ligament reconstruction and 34-weeks of physiotherapy performed unilateral strength training for both lower limbs. Four-weeks of conventional physiotherapy at week-30 were given, confirming the inability to gain torque. Then, steadiness training (isometric knee extension with visual biofeedback) was given for 7-weeks. Knee quadriceps peak torque, strength improvement, determination of responders to the intervention, coherence of strength gain between limbs, and self-reported outcomes (pain and knee stability) were obtained. Descriptive statistics and data inference using mixed-ANOVA, McNemar test, and χ2 test were described. Findings Quadriceps torque in the reconstructed knee improved (98.2 ± 47.2-155.2 ± 78.9 Nm; p = 0.031) for most patients (84%). Nevertheless, the torque was lower than the healthy side maintaining asymmetry (155.2 ± 78.9 vs. 209.5 ± 101.8 Nm; p = 0.026). There was high (20%) and medium coherence (80%) between limbs. Knee stability and pain improved in 72% of the patients (p < 0.001). Interpretations Steadiness training after anterior cruciate ligament reconstruction followed 9 months of surgery and failed conventional physiotherapy, improves the persistent weakness and self-reported outcomes, but gain strength was dissimilar between limbs.

Patients with chronic unilateral anterior knee pain experience bilateral deficits in quadriceps function and lower quarter flexibility: a cross-sectional study.

BACKGROUND: Little is known about how chronic unilateral anterior knee pain (AKP) affects bilateral quadriceps function and lower quarter flexibility. OBJECTIVE: To determine if patients with chronic unilateral AKP present bilateral deficits in quadriceps function and lower quarter flexibility. METHODS: Twenty-two patients with chronic unilateral AKP (pain duration: 48.6 months) and 22 matched healthy controls were evaluated. Pain perception and functional outcomes were obtained. Knee joint and thigh circumferences, quadriceps subcutaneous tissue thickness and function (i.e. maximal and explosive strength, activation, and endurance), and lower quarter flexibility (i.e. hamstrings and iliopsoas/rectus femoris muscle) in both legs were compared across conditions. RESULTS: Knee joint and thigh circumferences, and quadriceps subcutaneous tissue thickness were not different between conditions (P ≥ .39). Compared with matched healthy controls, patients with chronic unilateral AKP showed: 1) greater pain perception (0.0 versus 4.4 cm, P < .0001); 2) a lower score for functional outcomes (79.6 versus 53.9, P < .0001); 3) less bilateral quadriceps maximal (3.5 versus 2.8 Nm/kg, P < .0001) and explosive (10.8 versus 8.7 Nm/kg/s, P = .01) strength, activation (0.95 versus 0.83, P < .0001), and endurance (1.66 versus 1.52 Nm/kg, P = .02); and 4) less bilateral hamstrings (86.8 versus 72.6°, P = .002) and iliopsoas/rectus femoris (11.6 versus 7.8°, P < .05) flexibility. CONCLUSION: Patients with chronic unilateral AKP (without knee joint effusion or quadriceps muscle atrophy) appear to have bilateral deficits in quadriceps function and lower quarter flexibility, which should be addressed with pain reduction.

Arthrogenic muscle inhibition and return to sport after arthrofibrosis complicating anterior cruciate ligament surgery.

Arthrofibrosis is a devastating complication after Anterior Cruciate Ligament reconstruction (ACLr) characterized by a muscle weakness secondary to an arthrogenic muscle inhibition process. The loss of knee isokinetic strength due to arthrogenic muscle inhibition may be more important after arthrofibrosis, compared to an ACLr population with no complication. The isokinetic strength deficit [Limb Symmetry Index (LSI) at 60 and 180°/s of angular speed] was measured at 4, 7 and 12 post-operative months. Knee function, return to running and return to sport were evaluated. A comparison of the Quadriceps and the Hamstring LSI between patients with arthrofibrosis and those without post-operative complication was performed according to time and taking into consideration the type of surgical procedure. 539 primary ACLr patients were assessed. The arthrofibrosis group presented at 4, 7 and 12 post-operative months a Quadriceps LSI significantly lower compared to the control group, without influence of the graft procedure (LSI: 38, 53, 68% vs 63, 73, 85% at 60°/s, respectively). The Hamstring LSI was significantly lower at 4 and 7 post-operative months, but comparable at 12 months with an influence of the Hamstring procedure. Knee function was significantly lower at 4 and 7 post-operative months. Few arthrofibrosis ACLr patients returned to running at 7 post-operative months (6.8% vs 69.9%; p < .0001). An important and durable Quadriceps muscle weakness occurred after arthrofibrosis, whatever the type of graft procedure. This is explained by an Arthrogenic muscle inhibition which compromised the return to sport at the same level until 12 post-operative months.HighlightsAn important and durable quadriceps muscle weakness occurred after arthrofibrosis.The arthrogenic muscle inhibition was significant on the operated side independently of the type of the graft procedure.Arthrogenic muscle inhibition compromised the return to sport at the same level until 12 post-operative months.

A Review of the Relationships Between Knee Pain and Movement Neuromechanics.

CONTEXT: Knee injury and disease are common, debilitating, and expensive. Pain is a chief symptom of knee injury and disease and likely contributes to arthrogenic muscle inhibition. Joint pain alters isolated motor function, muscular strength, and movement biomechanics. Because knee pain influences biomechanics, it likely also influences long-term knee joint health. OBJECTIVE: The purpose of this article is 2-fold: (1) review effects of knee pain on lower-extremity muscular activation and corresponding biomechanics and (2) consider potential implications of neuromechanical alterations associated with knee pain for long-term knee joint health. Experimental knee pain is emphasized because it has been used to mimic clinical knee pain and clarify independent effects of knee pain. Three common sources of clinical knee pain are also discussed: patellofemoral pain, anterior cruciate ligament injury and reconstruction, and knee osteoarthritis. DATA SOURCES: The PubMed, Web of Science, and SPORTDiscus databases were searched for articles relating to the purpose of this article. CONCLUSION: Researchers have consistently reported that knee pain alters neuromuscular activation, often in the form of inhibition that likely occurs via voluntary and involuntary neural pathways. The effects of knee pain on quadriceps activation have been studied extensively. Knee pain decreases voluntary and involuntary quadriceps activation and strength and alters the biomechanics of various movement tasks. If allowed to persist, these neuromechanical alterations might change the response of articular cartilage to joint loads during movement and detrimentally affect long-term knee joint health. Physical rehabilitation professionals should consider neuromechanical effects of knee pain when treating knee injury and disease. Resolution of joint pain can likely help to restore normal movement neuromechanics and potentially improve long-term knee joint health and should be a top priority.

Gluteal Central Activation in Females With Patellofemoral Pain: A Preliminary Study.

CONTEXT: Lesser hip muscle strength is commonly observed in females with patellofemoral pain (PFP) compared with females without PFP and is associated with poor subjective function and single-leg squat (SLS) biomechanics. Hip muscle weakness is theorized to be related to PFP, suggesting centrally mediated muscle inhibition may influence the observed weakness. The central activation ratio (CAR) is a common metric used to quantify muscle inhibition via burst superimposition. However, gluteal inhibition has yet to be evaluated using this approach in females with PFP. The study objectives are to (1) describe gluteal activation in the context of subjective function, hip strength, and squatting biomechanics and (2) examine the relationship of gluteal activation with subjective function and squatting biomechanics in females with PFP. DESIGN: Cross-sectional. METHODS: Seven females with PFP (age = 22.8 [3.6] y; mass = 69.4 [18.0] kg; height = 1.67 [0.05] m, duration of pain = 6-96 mo) completed this study. Subjective function was assessed with the Anterior Knee Pain Scale, while fear-avoidance beliefs were assessed with the Fear-Avoidance Belief Questionnaire physical activity and work subscales. Biomechanical function was assessed with peak hip and knee angles and moments in the sagittal and frontal planes during SLS. Gluteus medius (GMed) and gluteus maximus (GMax) activation were assessed with the CAR. Descriptive statistics were calculated, and relationships between variables were assessed with Spearman rho correlations. RESULTS: The CAR of GMed and GMax was 90.5% (8.1%) and 84.0% (6.3%), respectively. Lesser GMed CAR was strongly associated with greater hip adduction during SLS (ρ = -.775, P = .02) and greater fear-avoidance beliefs-physical activity subscale (ρ = -.764, P = .018). CONCLUSION: We found a wide range in GMed and GMax activation across females with PFP. Lesser GMed activation was associated with greater hip adduction during SLS and fear of physical activity, suggesting that gluteal inhibition should be assessed in patients with PFP.

Investigation of Effectiveness of Two Different Kinesiotaping Techniques in Myofascial Pain Syndrome: An Open-Label Randomized Clinical Trial.

BACKGROUND: Myofascial pain syndrome is a regional musculoskeletal pain syndrome characterized by trigger points. Although there are widely accepted treatment modalities, there is no gold standard treatment. Kinesiotaping represents an interesting modality in the treatment of musculoskeletal disorders and attracts attention with studies emerging in the recent years, but in spite of the proposed benefits of kinesiotaping, its efficacy is still unclear, thus further studies evaluating the effectiveness of kinesiotaping are needed. OBJECTIVES: We aimed to investigate, not only the effectiveness of kinesiotaping applied with the space correction and muscle inhibition techniques (compared to the home exercise program in reducing pain and improving functional status and quality of life in female patients with myofascial pain syndrome related to active trigger points in the upper trapezius), but also to evaluate the superiority of the 2 techniques over each other. STUDY DESIGN: An open-label randomized clinical trial with a parallel assignment intervention model. SETTING: The physical medicine and rehabilitation clinics in Istanbul University, Istanbul Faculty of Medicine. METHODS: Seventy-one female patients with the complaint of pain in the upper trapezius region, diagnosed with myofascial pain syndrome, and having at least one active trigger point in the upper trapezius fibers, were randomly assigned by a computer program to 1 of the 3 groups: kinesiotaping with the space correction technique (KSCT, n = 20), kinesiotaping with the muscle inhibition technique (KMIT, n = 24), and the home exercise program alone (control group [CG], n = 27). The patients were evaluated by the numerical rating scale for pain intensity, the neck disability index for functional status, and the 36-Item Short-Form Health Survey for quality of life in the beginning of the study and at the first, second, and sixth weeks (1-month follow-up). RESULTS: Kinesiotaping was associated with lower pain intensity levels (P = 0.019 at the first week and P = 0.026 at the second week) and better functional status (P = 0.011 at the second week) and it was effective in increasing quality of life by improving physical functions and general health (P = 0.033 and P = 0.003 at the second week, respectively) earlier than in the CG. Role limitations due to physical factors improved in the KMIT group earlier than in the other groups (P = 0.022 at the second week). LIMITATIONS: Being performed in a limited number of female patients only, absence of a placebo group, and lack of blinded assessments. CONCLUSION: Both kinesiotaping methods were associated with lower pain intensity levels and better functional status and were effective in increasing quality of life by improving physical functions and general health earlier than the home exercise program. There was no significant difference between the kinesiotaping methods, except for role limitations due to the physical factors domain of SF-36 which was improved in the KMIT group earlier than in the KSCT group and CGs.

Effects of the Suboccipital Muscle Inhibition Technique on the Range of Motion of the Ankle Joint and Balance According to Its Application Duration: A Randomized Controlled Trial.

This study aimed to investigate the effects of suboccipital muscle inhibition technique (SMIT) on active range of motion (AROM) of the ankle joint, lunge angle (LA), and balance in healthy adults, according to the duration of its application. A total of 80 participants were randomly allocated to the 4-min suboccipital muscle inhibition (SMI) group (SMI_4M, n = 20), 8-min SMI group (n = 20), 4-min sham-SMI (SSMI) group (n = 20), and 8-min SSMI group (n = 20). Accordingly, the SMIT and sham SMIT were applied for 4 min or 8 min in the respective groups. AROM of dorsiflexion and LA were assessed, and a single leg balance test (SLBT) was performed before and after the intervention. AROM (4 min, p < 0.001; 8 min, p < 0.001), LA (4 min, p < 0.001; 8 min, p < 0.001), and SLBT (4 min, p < 0.001; 8 min, p < 0.001) significantly improved after SMI application. Compared with the SSMI group, the SMI group showed a significant increase in AROM (p < 0.001), LA (p < 0.001), and SLBT (p < 0.001). Except for SLBT (p = 0.016), there were no significant interactions between intervention and application duration. The results suggest that the SMIT, at durations of both 4 and 8 min, could be effective tools for improving AROM, LA, and balance.