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J. Ty Hopkins and Christopher D. Ingersoll

Objectives:

To define the concept of arthrogenic muscle inhibition (AMI), to discuss its implications in the rehabilitation of joint injury, to discuss the neurophysiologic events that lead to AMI, to evaluate the methods available to measure AM1 and the models that might be implemented to examine AMI, and to review therapeutic interventions that might reduce AMI.

Data Sources:

The databases MEDLINE, SPORTDiscus, and CIHNAL were searched with the terms reflex inhibition, joint mechanoreceptor, Ib interneuron, Hoffmann reflex, effusion, and joint injury. The remaining citations were collected from references of similar papers.

Conclusions:

AMI is a limiting factor in the rehabilitation of joint injury. It results in atrophy and deficiencies in strength and increases the susceptibility to further injury. A therapeutic intervention that results in decreased inhibition, allowing for active exercise, would lead to faster and more complete recovery.

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Cody B. Bremner, William R. Holcomb, Christopher D. Brown and Melanie E. Perreault

Clinical Scenario:

Orthopedic knee conditions are regularly treated in sports-medicine clinics. Rehabilitation protocols for these conditions are often designed to address the associated quadriceps strength deficits. Despite these efforts, patients with orthopedic knee conditions often fail to completely regain their quadriceps strength. Disinhibitory modalities have recently been suggested as a clinical tool that can be used to counteract the negative effects of arthrogenic muscle inhibition, which is believed to limit the effectiveness of therapeutic exercise. Neuromuscular electrical stimulation (NMES) is commonly accepted as a strengthening modality, but its ability to simultaneously serve as a disinhibitory treatment is not as well established.

Clinical Question:

Does NMES effectively enhance quadriceps voluntary activation in patients with orthopedic knee conditions?

Summary of Key Findings:

Four randomized controlled trials (RCTs) met the inclusion criteria and were included. Of those, 1 reported statistically significant improvements in quadriceps voluntary activation in the intervention group relative to a comparison group, but the statistical significance was not true for another study consisting of the same sample of participants with a different follow-up period. One study reported a trend in the NMES group, but the between-groups differences were not statistically significant in 3 of the 4 RCTs.

Clinical Bottom Line:

Current evidence does not support the use of NMES for the purpose of enhancing quadriceps voluntary activation in patients with orthopedic knee conditions.

Strength of Recommendation:

There is level B evidence that the use of NMES alone or in conjunction with therapeutic exercise does not enhance quadriceps voluntary activation in patients with orthopedic knee conditions (eg, anterior cruciate ligament injuries, osteoarthritis, total knee arthroplasty).

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Dana M. Otzel, Chris J. Hass, Erik A. Wikstrom, Mark D. Bishop, Paul A. Borsa and Mark D. Tillman

leading to CAI are unclear, arthrogenic muscle inhibition (AMI) may contribute to the recurrent dysfunction and joint instability symptoms. 7 AMI is the diminished ability to contract the musculature surrounding an injured joint and is associated with reduction in motoneuron (MN) pool recruitment. 8

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Kyung-Min Kim, Christopher D. Ingersoll and Jay Hertel

Context:

Focal ankle-joint cooling (FAJC) has been shown to increase Hoffmann (H) reflex amplitudes of select leg muscles while subjects lie prone, but it is unknown whether the neurophysiological cooling effects persist in standing.

Objective:

To assess the effects of FAJC on H-reflexes of the soleus and fibularis longus during 3 body positions (prone, bipedal, and unipedal stances) in individuals with and without chronic ankle instability (CAI).

Design:

Crossover.

Setting:

Laboratory.

Participants:

15 young adults with CAI (9 male, 6 female) and 15 healthy controls.

Intervention:

All subjects received both FAJC and sham treatments on separate days in a randomized order. FAJC was accomplished by applying a 1.5-L plastic bag filled with crushed ice to the ankle for 20 min. Sham treatment involved room-temperature candy corn.

Main Outcome Measures:

Maximum amplitudes of H-reflexes and motor (M) waves were recorded while subjects lay prone and then stood in quiet bipedal and unipedal stances before and immediately after each treatment. Primary outcome measures were Hmax:Mmax ratios for the soleus and fibularis longus. Three-factor (group × treatment condition × time) repeated-measures ANOVAs and Fisher LSD tests were performed for statistical analyses.

Results:

Significant interactions of treatment condition by time for prone Hmax:Mmax ratios were found in the soleus (P = .001) and fibularis longus (P = .003). In both muscles, prone Hmax:Mmax ratios moderately increased after FAJC but not after sham treatment. The CAI and healthy groups responded similarly to FAJC. In contrast, there were no significant interactions or main effects in the bipedal and unipedal stances in either muscle (P > .05).

Conclusions:

FAJC moderately increased H-reflex amplitudes of the soleus and fibularis longus while subjects were prone but not during bipedal or unipedal standing. These results were not different between groups with and without CAI.

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Jihong Park, W. Matt Denning, Jordan D. Pitt, Devin Francom, J. Ty Hopkins and Matthew K. Seeley

Context:

Although knee pain is common, some facets of this pain are unclear. The independent effects (ie, independent from other knee injury or pathology) of knee pain on neural activation of lower-extremity muscles during landing and jumping have not been observed.

Objective:

To investigate the independent effects of knee pain on lower-extremity muscle (gastrocnemius, vastus medialis, medial hamstrings, gluteus medius, and gluteus maximus) activation amplitude during landing and jumping, performed at 2 different intensities.

Design:

Laboratory-based, pretest, posttest, repeated-measures design, where all subjects performed both data-collection sessions.

Methods:

Thirteen able-bodied subjects performed 2 different land and jump tasks (forward and lateral) under 2 different conditions (control and pain), at 2 different intensities (high and low). For the pain condition, experimental knee pain was induced via a hypertonic saline injection into the right infrapatellar fat pad. Functional linear models were used to evaluate the influence of experimental knee pain on muscle-activation amplitude throughout the 2 land and jump tasks.

Results:

Experimental knee pain independently altered activation for all of the observed muscles during various parts of the 2 different land and jump tasks. These activation alterations were not consistently influenced by task intensity.

Conclusion:

Experimental knee pain alters activation amplitude of various lower-extremity muscles during landing and jumping. The nature of the alteration varies between muscles, intensities, and phases of the movement (ie, landing and jumping). Generally, experimental knee pain inhibits the gastrocnemius, medial hamstring, and gluteus medius during landing while independently increasing activation of the same muscles during jumping.

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Brandon Warner, Kyung-Min Kim, Joseph M. Hart and Susan Saliba

Context:

Quadriceps function improves after application of focal joint cooling or transcutaneous electrical nerve stimulation to the knee in patients with arthrogenic muscle inhibition (AMI), yet it is not known whether superficial heat is able to produce a similar effect.

Objective:

To determine quadriceps function after superficial heat to the knee joint in individuals with AMI.

Design:

Single blinded randomized crossover.

Setting:

Laboratory.

Patients:

12 subjects (4 female, 8 males; 25.6 ± 7.7 y, 177.2 ± 12.7 cm, 78.4 ± 18.2 kg) with a history of knee-joint pathology and AMI, determined with a quadriceps central activation ratio (CAR) of <90%.

Intervention:

3 treatment conditions for 15 min on separate days: superficial heat using a cervical moist-heat pack (77°C), sham using a cervical moist pack (room temperature at about 24°C), and control (no treatment). All subjects received all treatment conditions in a randomized order.

Main Outcome Measures:

Central activation ratio and knee-extension torque during maximal voluntary isometric contraction with the knee flexed to 60° were collected at pre, immediately post, 30 min post, and 45 min posttreatment. Skin temperature of the quadriceps and knee and room temperature were also recorded at the same time points.

Results:

Three (treatment conditions) by 4 (time) repeated ANOVAs found that there were no significant interactions or main effects in either CAR or knee-extension torque (all P > .05). Skin-temperature 1-way ANOVAs revealed that the skin temperature in the knee during superficial heat was significantly higher than other treatment conditions at all time points (P < .05).

Conclusions:

Superficial heat to the knee joint using a cervical moist-heat pack did not influence quadriceps function in individuals with AMI in the quadriceps.

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Christopher Kuenze, Jay Hertel and Joseph M. Hart

Purpose:

Persistent quadriceps weakness due to arthrogenic muscle inhibition (AMI) has been reported after anterior cruciate ligament (ACL) reconstruction. Fatiguing exercise has been shown to alter lower extremity muscle function and gait mechanics, which may be related to injury risk. The effects of exercise on lower extremity function in the presence of AMI are not currently understood. The purpose of this study was to compare the effect of 30 min of exercise on quadriceps muscle function and soleus motoneuron-pool excitability in ACL-reconstructed participants and healthy controls.

Methods:

Twenty-six (13 women, 13 men) healthy and 26 (13 women, 13 men) ACL-reconstructed recreationally active volunteers were recruited for a case-control laboratory study. All participants completed 30 min of continuous exercise including alternating cycles of inclined-treadmill walking and bouts of squats and step-ups. Knee-extension torque, quadriceps central activation ratio (CAR), soleus H:M ratio, and soleus V:M ratio were measured before and after 30 min of exercise.

Results:

There was a significant group × time interaction for knee-extension torque (P = .002), quadriceps CAR (P = .03), and soleus V:M ratio (P = .03). The effect of exercise was smaller for the ACL-R group than for matched controls for knee-extension torque (ACL-R: %Δ = −4.2 [−8.7, 0.3]; healthy: %Δ = −14.2 [−18.2, −10.2]), quadriceps CAR (ACL-R: %Δ = −5.1 [−8.0, −2.1]; healthy: %Δ = −10.0 [−13.3, −6.7]), and soleus V:M ratio (ACL-R: %Δ = 37.6 [2.1, 73.0]; healthy: %Δ = −24.9 [−38.6, −11.3]).

Conclusion:

Declines in quadriceps and soleus volitional muscle function were of lower magnitude in ACL-R subjects than in healthy matched controls. This response suggests an adaptation experienced by patients with quadriceps AMI that may act to maintain lower extremity function during prolonged exercise.

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* Marilyn Dayton * Mitchell L. Cordova * Christopher D. Ingersoll * Mark A. Merrick * 5 2000 9 2 124 134 10.1123/jsr.9.2.124 Research Reviews Arthrogenic Muscle inhibition: A Limiting Factor in Joint Rehabilitation J. Ty Hopkins * Christopher D. Ingersoll * 5 2000 9 2 135 159 10.1123/jsr.9

Open access

Pier Paolo Mariani, Luca Laudani, Jacopo E. Rocchi, Arrigo Giombini and Andrea Macaluso

underlying factor contributing to this problem is the arthrogenic muscle inhibition, which remains understudied. Different studies 15 – 17 have demonstrated that muscular wasting occurs mainly during the first postoperative month, suggesting that there is a surgically induced effect that occurs immediately

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M. Spencer Cain, Kyeongtak Song, J. Troy Blackburn, Kimmery Migel and Erik A. Wikstrom

.4085/1062-6050-47.6.11 23182009 30. McVey ED , Palmieri RM , Docherty CL , Zinder SM , Ingersoll CD . Arthrogenic muscle inhibition in the leg muscles of subjects exhibiting functional ankle instability . Foot Ankle Int . 2005 ; 26 ( 12 ): 1055 – 1061 . PubMed ID: 16390639 doi: 10