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Churchill L, John Bade M, Koonce RC, Stevens-Lapsley JE, Bandholm T. The past and future of peri-operative interventions to reduce arthrogenic quadriceps muscle inhibition after total knee arthroplasty: A narrative review. OSTEOARTHRITIS AND CARTILAGE OPEN 2024; 6:100429. [PMID: 38304413 PMCID: PMC10832271 DOI: 10.1016/j.ocarto.2023.100429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 12/16/2023] [Indexed: 02/03/2024] Open
Abstract
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.
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Affiliation(s)
- Laura Churchill
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Michael John Bade
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Eastern Colorado VA Geriatric Research Education and Clinical Center (GRECC), Aurora, CO, USA
| | - Ryan C. Koonce
- Department of Orthopaedic Surgery, University of Colorado School of Medicine, Highlands Ranch, CO, USA
| | - Jennifer E. Stevens-Lapsley
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Eastern Colorado VA Geriatric Research Education and Clinical Center (GRECC), Aurora, CO, USA
| | - Thomas Bandholm
- Physical Medicine & Rehabilitation Research-Copenhagen (PMR-C), Department of Physical and Occupational Therapy, Copenhagen University Hospital Amager-Hvidovre, Hvidovre, Denmark
- Department of Clinical Research, Copenhagen University Hospital Amager-Hvidovre, Hvidovre, Denmark
- Department of Orthopedic Surgery, Copenhagen University Hospital Amager-Hvidovre, Hvidovre, Denmark
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García-Sillero M, Maroto-Izquierdo S, Galván-García M, Benitez-Porres J, Vargas-Molina S, Jurado-Castro JM. Acute Effects of Blood Flow Restriction Training on Movement Velocity and Neuromuscular Signal during the Back Squat Exercise. J Clin Med 2023; 12:4824. [PMID: 37510938 PMCID: PMC10381307 DOI: 10.3390/jcm12144824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/30/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
The aim of this study was to verify the effects of blood flow restriction on movement velocity and muscle activity during the back squat exercise. METHODS Twenty-four university students participated in this study. In two randomized sessions 72 h apart, participants performed a 4-set protocol consisting of 30-15-15-15 repetitions performed at 30% of their one-repetition maximum in the back squat exercise. In both sessions, neuromuscular function was monitored by surface electromyography (EMG) and movement velocity (mean propulsive velocity (MPV), peak concentric velocity (Vmax), and the effort index (EI)). Blood flow restriction (BFR) was applied during exercise in one of the experimental sessions with 80% of full arterial occlusion pressure over lower limbs. RESULTS The BFR condition showed higher (p < 0.05) EI, peak, and rooted mean square normalized EMG in Set 1 compared to Set 2. Similar MPV and Vmax were observed in each set for both the BFR and control conditions. No significant differences were observed between conditions in any set. CONCLUSIONS BFR did not imply changes in neuromuscular performance during low-intensity resistance training, but it might induce greater intra-series velocity loss and less excitation of the muscles involved.
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Affiliation(s)
- Manuel García-Sillero
- Physical Education and Sport, Faculty of Medicine, EADE-University of Wales Trinity Saint David, 29018 Malaga, Spain
| | - Sergio Maroto-Izquierdo
- Department of Health Sciences, European University Miguel de Cervantes (UEMC), 47012 Valladolid, Spain
| | - María Galván-García
- Physical Education and Sport, Faculty of Medicine, EADE-University of Wales Trinity Saint David, 29018 Malaga, Spain
| | - Javier Benitez-Porres
- Physical Education and Sport, Faculty of Medicine, University of Málaga, 29016 Málaga, Spain
| | - Salvador Vargas-Molina
- Physical Education and Sport, Faculty of Medicine, EADE-University of Wales Trinity Saint David, 29018 Malaga, Spain
| | - Jose Manuel Jurado-Castro
- Metabolism and Investigation Unit, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, 14004 Cordoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Ciencias De La Actividad Física y El Deporte, Escuela Universitaria de Osuna (Centro Adscrito a la Universidad de Sevilla), 41640 Osuna, Spain
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Hamstrings fatigue does not improve quadriceps function in individuals with anterior cruciate ligament reconstruction. Phys Ther Sport 2023; 61:20-26. [PMID: 36841118 DOI: 10.1016/j.ptsp.2023.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023]
Abstract
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.
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Arthrogenic Muscle Inhibition Following Anterior Cruciate Ligament Injury. J Sport Rehabil 2022; 31:694-706. [PMID: 35168201 DOI: 10.1123/jsr.2021-0128] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 10/06/2021] [Accepted: 10/28/2021] [Indexed: 11/18/2022]
Abstract
Arthrogenic muscle inhibition (AMI) is a common impairment in individuals who sustain an anterior cruciate ligament (ACL) injury. The AMI causes decreased muscle activation, which impairs muscle strength, leading to aberrant movement biomechanics. The AMI is often resistant to traditional rehabilitation techniques, which leads to persistent neuromuscular deficits following ACL reconstruction. To better treat AMI following ACL injury and ACL reconstruction, it is important to understand the specific neural pathways involved in AMI pathogenesis, as well as the changes in muscle function that may impact movement biomechanics and long-term structural alterations to joint tissue. Overall, AMI is a critical factor that limits optimal rehabilitation outcomes following ACL injury and ACL reconstruction. This review discusses the current understanding of the: (1) neural pathways involved in the AMI pathogenesis following ACL injury; (2) consequence of AMI on muscle function, joint biomechanics, and patient function; and (3) development of posttraumatic osteoarthritis. Finally, the authors review the evidence for interventions specifically used to target AMI following ACL injury.
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Arthrogenic Muscle Inhibition: Best Evidence, Mechanisms, and Theory for Treating the Unseen in Clinical Rehabilitation. J Sport Rehabil 2021; 31:717-735. [PMID: 34883466 DOI: 10.1123/jsr.2021-0139] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 08/06/2021] [Accepted: 09/07/2021] [Indexed: 11/18/2022]
Abstract
CONTEXT Arthrogenic muscle inhibition (AMI) impedes the recovery of muscle function following joint injury, and in a broader sense, acts as a limiting factor in rehabilitation if left untreated. Despite a call to treat the underlying pathophysiology of muscle dysfunction more than three decades ago, the continued widespread observations of post-traumatic muscular impairments are concerning, and suggest that interventions for AMI are not being successfully integrated into clinical practice. OBJECTIVES To highlight the clinical relevance of AMI, provide updated evidence for the use of clinically accessible therapeutic adjuncts to treat AMI, and discuss the known or theoretical mechanisms for these interventions. EVIDENCE ACQUISITION PubMed and Web of Science electronic databases were searched for articles that investigated the effectiveness or efficacy of interventions to treat outcomes relevant to AMI. EVIDENCE SYNTHESIS 122 articles that investigated an intervention used to treat AMI among individuals with pathology or simulated pathology were retrieved from 1986 to 2021. Additional articles among uninjured individuals were considered when discussing mechanisms of effect. CONCLUSION AMI contributes to the characteristic muscular impairments observed in patients recovering from joint injuries. If left unresolved, AMI impedes short-term recovery and threatens patients' long-term joint health and well-being. Growing evidence supports the use of neuromodulatory strategies to facilitate muscle recovery over the course of rehabilitation. Interventions should be individualized to meet the needs of the patient through shared clinician-patient decision-making. At a minimum, we propose to keep the treatment approach simple by attempting to resolve inflammation, pain, and effusion early following injury.
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Lee H, Shin J, Kim D, Park J. Effect of verbal encouragement on quadriceps and knee joint function during three sets of knee extension exercise. ISOKINET EXERC SCI 2021. [DOI: 10.3233/ies-203203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND: Although the common practice of verbal encouragement is scientifically supported, its effect on the maintenance of force output in fatiguing exertions is unknown. OBJECTIVE: To examine the effects of verbal encouragement on exercise-induced quadriceps and knee joint function during three sets of knee extension exercise. METHODS: Sixty-five healthy males (23.3 years, 175.8 cm, 75.3 kg) underwent testing using the administration of verbal encouragement (n= 32) or not (n= 33) during assessment of quadriceps and knee joint function. Assessments were performed at baseline and times 1, 2, and 3. The knee concentric isokinetic extension at 60∘/s, was performed between the time points. For quadriceps function, maximal isometric strength and activation (central activation ratio) were recorded. Absolute error values on knee flexion replications at 15∘ or 45∘ were recorded for knee joint function. RESULTS: There was no verbal encouragement effect over three sets of exercise in quadriceps strength (condition × time: F3,189= 1.71, p= 0.17) and knee flexion replication (condition × time for 15∘: F3,189= 0.11, p= 0.96; 45∘: F3,189= 0.63, p= 0.6). However, subjects who had received verbal encouragement maintained quadriceps activation (condition × time: F3,189= 5.49, p= 0.001). Specifically, quadriceps activation in the verbal condition was 3.0% higher at time 2 (p= 0.01) and 4.7% higher at time 3 (p= 0.0003) versus in the non-verbal condition. CONCLUSIONS: Verbal encouragement appears to be effective in maintaining central activation, but is insufficient for promoting strength. This supports the idea that peripheral contributing factors play a larger role in force production when performing multiple sets of exercises.
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Petraş A, Drăgoi RG, Pupazan V, Drăgoi M, Popa D, Neagu A. Using Portable Ultrasound to Monitor the Neuromuscular Reactivity to Low-Frequency Electrical Stimulation. Diagnostics (Basel) 2021; 11:diagnostics11010065. [PMID: 33401607 PMCID: PMC7824493 DOI: 10.3390/diagnostics11010065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/26/2020] [Accepted: 12/28/2020] [Indexed: 01/19/2023] Open
Abstract
Neuromuscular electrical stimulation (NMES) is useful for muscle strengthening and for motor restoration of stroke patients. Using a portable ultrasound instrument, we developed an M-mode imaging protocol to visualize contractions elicited by NMES in the quadriceps muscle group. To quantify muscle activation, we performed digital image processing based on the Teager–Kaiser energy operator. The proposed method was applied for 35 voluntary patients (18 women and 17 men), of 63.8 ± 14.1 years and body mass index (BMI) 30.2 ± 6.70 kg/m2 (mean ± standard deviation). Biphasic, rectangular electric pulses of 350 µs duration were applied at two frequencies (60 Hz and 120 Hz), and ultrasound was used to assess the sensory threshold (ST) and motor threshold (MT) amplitude of the NMES signal. The MT was 23.4 ± 4.94 mA, whereas the MT to ST ratio was 2.69 ± 0.57. Linear regression analysis revealed that MT correlates poorly with body mass index (R2 = 0.004) or with the thickness of the subcutaneous adipose tissue layer that covers the treated muscle (R2 = 0.013). Our work suggests that ultrasound is suitable to visualize neuromuscular reactivity during electrotherapy. The proposed method can be used in the clinic, enabling the physiotherapist to establish personalized treatment parameters.
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Affiliation(s)
- Alin Petraş
- Department of Medical Rehabilitation, Balneology and Rheumatology, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041 Timişoara, Romania; (A.P.); (M.D.); (D.P.)
| | - Răzvan Gabriel Drăgoi
- Department of Medical Rehabilitation, Balneology and Rheumatology, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041 Timişoara, Romania; (A.P.); (M.D.); (D.P.)
- Correspondence:
| | - Vasile Pupazan
- Department of Functional Sciences, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041Timişoara, Romania; (V.P.); (A.N.)
| | - Mihai Drăgoi
- Department of Medical Rehabilitation, Balneology and Rheumatology, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041 Timişoara, Romania; (A.P.); (M.D.); (D.P.)
| | - Daniel Popa
- Department of Medical Rehabilitation, Balneology and Rheumatology, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041 Timişoara, Romania; (A.P.); (M.D.); (D.P.)
| | - Adrian Neagu
- Department of Functional Sciences, Victor Babeş University of Medicine and Pharmacy Timişoara, 300041Timişoara, Romania; (V.P.); (A.N.)
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
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Yu S, Lowe T, Griffin L, Dong XN. Single bout of vibration-induced hamstrings fatigue reduces quadriceps inhibition and coactivation of knee muscles after anterior cruciate ligament (ACL) reconstruction. J Electromyogr Kinesiol 2020; 55:102464. [PMID: 32942109 DOI: 10.1016/j.jelekin.2020.102464] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 10/23/2022] Open
Abstract
Persistent quadriceps strength deficits in individuals with anterior cruciate ligament reconstruction (ACLr) have been attributed to arthrogenic muscle inhibition (AMI). The purpose of the present study was to investigate the effect of vibration-induced hamstrings fatigue on AMI in patients with ACLr. Eight participants with unilateral ACLr (post-surgery time: M = 46.5, SD = 23.5 months; age: M = 21.4, SD = 1.4 years) and eight individuals with no previous history of knee injury (age: M = 22.5, SD = 2.5 years) were recruited. A fatigue protocol, consisting of 10 min of prolonged local hamstrings vibration, was applied to both the ACLr and control groups. The central activation ratio (CAR) of the quadriceps was measured with a superimposed burst of electrical stimulation, and hamstrings/quadriceps coactivation was assessed using electromyography (EMG) during isometric knee extension exercises, both before and after prolonged local vibration. For the ACLr group, the hamstrings strength, measured by a load cell on a purpose-built chair, was significantly (P = 0.016) reduced about 14.5%, indicating fatigue was actually induced in the hamstrings. At baseline, the ACLr group showed a trend (P = 0.051) toward a lower quadriceps CAR (M = 93.2%, SD = 6.2% versus M = 98.1%, SD = 1.1%) and significantly (P = 0.001) higher hamstrings/quadriceps coactivation (M = 15.1%, SD = 6.2% versus M = 7.5%, SD = 4.0%) during knee extension compared to the control group. The fatigue protocol significantly (P = 0.001) increased quadriceps CAR (from M = 93.2%, SD = 6.2% to M = 97.9%, SD = 2.8%) and significantly (P = 0.006) decreased hamstrings/quadriceps coactivation during knee extension (from M = 15.1%, SD = 6.2% to M = 9.5%, SD = 4.5%) in the ACLr group. In conclusion, vibration-induced hamstrings fatigue can alleviate AMI of the quadriceps in patients with ACLr. This finding has clinical implications in the management of recovery for ACLr patients with quadriceps strength deficits and dysfunction.
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Affiliation(s)
- Shiqi Yu
- Department of Health and Kinesiology, The University of Texas at Tyler, Tyler, TX, USA
| | - Timothy Lowe
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA
| | - Lisa Griffin
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA
| | - Xuanliang Neil Dong
- Department of Health and Kinesiology, The University of Texas at Tyler, Tyler, TX, USA.
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Central Activation Ratio Is a Reliable Measure for Gluteal Neuromuscular Function. J Sport Rehabil 2020; 29:956-962. [PMID: 31775118 DOI: 10.1123/jsr.2019-0243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/12/2019] [Accepted: 09/20/2019] [Indexed: 11/18/2022]
Abstract
CONTEXT Central activation ratio (CAR) is a common outcome measure used to quantify gross neuromuscular function of the quadriceps using the superimposed burst technique, yet this outcome measure has not been validated in the gluteal musculature. OBJECTIVE To quantify gluteus medius (GMed) and gluteus maximus (GMax) CAR in a healthy population and evaluate its validity and reliability over a 1-week period. DESIGN Descriptive. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 20 healthy participants (9 males and 11 females; age 22.2 [1.4] y, height 173.4 [11.1] cm, mass 84.8 [25.8] kg) were enrolled in this study. INTERVENTIONS Participants were assessed at 2 sessions, separated by 1 week. Progressive electrical stimuli (25%, 50%, 75%, and 100%) were delivered to the GMed and GMax at rest, and 100% stimuli were delivered during progressive hip abduction and extension contractions (25%, 50%, 75%, and 100% maximal voluntary isometric contraction). MAIN OUTCOME MEASURES GMed and GMax CAR, and hip abduction and hip extension maximal voluntary isometric contraction torque. Line of best fit and coefficient of determination (r2) were used to assess the relationship between torque output and CAR at varying levels of stimuli. Intraclass correlation coefficients, ICCs(3,k), were used to assess the between-session reliability. RESULTS GMed CAR was 96.1% (3.4%) and 96.6% (3.2%), on visits 1 and 2, respectively, whereas GMax CAR was 86.5% (7.5%) and 87.2% (10.7%) over the 2 sessions. A third-order polynomial demonstrated the best line of fit between varying superimposed burst intensities at rest for both GMed (r2 = .156) and GMax (r2 = .602). Linear relationships were observed in the CAR during progressive contractions with a maximal superimposed burst, GMed (r2 = .409) and GMax (r2 = .639). Between-session reliability was excellent for GMed CAR, ICC(3,k) = .911, and moderate for GMax CAR, ICC(3,k) = .704. CONCLUSION CAR appears to be an acceptable measure of GMed and GMax neuromuscular function in healthy individuals. Gluteal CAR measurements are reliable measures over a 1-week test period.
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Garcia SA, Rodriguez KM, Krishnan C, Palmieri-Smith RM. Type of measurement used influences central and peripheral contributions to quadriceps weakness after anterior cruciate ligament (ACL) reconstruction. Phys Ther Sport 2020; 46:14-22. [PMID: 32846386 DOI: 10.1016/j.ptsp.2020.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 12/26/2022]
Abstract
OBJECTIVE The relative contribution of muscle size and voluntary activation (VA) on quadriceps strength after anterior cruciate ligament (ACL) reconstruction remains inconclusive. Here, we aimed to determine the contributions of muscle size and VA on quadriceps strength in ACL-reconstructed patients and determine if contributions were similar if unilateral outcomes (i.e. ACL-reconstructed limb) or the LSI was used. DESIGN A cross-sectional study. SETTING A university research laboratory. PARTICIPANTS Sixteen individuals 6-12 months after ACL reconstruction (Age: 22.3 ± 6.0yr, Height: 1.7 ± 0.1 m, Mass: 68.7 ± 11.5 kg) were recruited. MAIN OUTCOME MEASURES Quadriceps isometric strength and VA, via the interpolated triplet technique, were assessed bilaterally. Ultrasound images were acquired of the vastus lateralis to calculate cross-sectional area (CSA) in both legs. LSI's were computed for all variables by expressing values of the reconstructed leg as a percent of the non-reconstructed leg. Separate stepwise linear regressions were performed to examine the contribution of VA and CSA on quadriceps strength. Model 1 used LSI for all outcomes and model 2 used outcomes from the reconstructed leg. RESULTS We observed between limb deficits of 27.78% in quadriceps strength, 13.61% in vastus lateralis CSA, and 13.18% in VA (P < 0.05). Strength LSI was significantly predicted by VA LSI (R2 = 0.45, P < 0.01), but not by CSA LSI (R2 = 0.01, P =0.87). Reconstructed leg strength was significantly predicted by VL CSA (R2 = 0.50, P < 0.01) but not quadriceps VA (R2 = 0.08, P =0.11). CONCLUSIONS The contributions of VA and CSA on quadriceps PT differed greatly if LSI or reconstructed leg outcomes were used. Evaluation of VA and CSA in unison may be provide a more holistic understanding of the sources of muscle weakness after ACL reconstruction.
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Affiliation(s)
- Steven A Garcia
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
| | | | - Chandramouli Krishnan
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA; Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, MI, USA; Robotics Institute, University of Michigan, Ann Arbor, MI, USA; Neuromuscular and Rehabilitation Robotics Laboratory, University of Michigan, Ann Arbor, MI, USA
| | - Riann M Palmieri-Smith
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA; Department of Orthopaedic Surgery, Michigan Medicine, Ann Arbor, MI, USA; Orthopaedic Rehabilitation and Biomechanics Laboratory, University of Michigan, Ann Arbor, MI, USA.
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Knee Joint and Quadriceps Dysfunction in Individuals With Anterior Knee Pain, Anterior Cruciate Ligament Reconstruction, and Meniscus Surgery: A Cross-Sectional Study. J Sport Rehabil 2020; 30:112-119. [PMID: 32234996 DOI: 10.1123/jsr.2018-0482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/01/2020] [Accepted: 01/26/2020] [Indexed: 11/18/2022]
Abstract
CONTEXT While arthrogenous muscle inhibition associated with knee injuries is evident, the relative magnitude of functional deficiency related to each individual knee pathology is unclear. OBJECTIVE To compare the knee joint and quadriceps dysfunction among patients with anterior knee pain (AKP) without surgical history and those with surgical history (anterior cruciate ligament reconstruction [ACLR]; meniscus surgery) without current AKP, with matched healthy controls. DESIGN Cross-sectional study. SETTING Laboratory. PARTICIPANTS A total of 66 patients with knee pathologies and 30 controls. MAIN OUTCOME MEASURES Pain perception and lower-extremity functional outcomes were assessed. Knee joint function was measured by replication tests. Quadriceps function was measured by strength, voluntary activation, and torque-generating capacity. RESULTS Patients with AKP reported greater pain perception compared with the other knee conditions (4.3 vs 0.1 of 10 in Numeric Pain Rating Scale, P < .0001). Compared with the controls: (1) patients with AKP showed a greater error on knee-flexion replications at 75° (2.9° vs 5.4°, P = .002), (2) patients with AKP and ACLR showed less quadriceps strength (AKP: 3.3 vs 2.6 N·m/kg, P = .002; ACLR: 3.3 vs 2.7 N·m/kg, P = .02) and voluntary activation (AKP: 0.982 vs 0.928, P < .0001; ACLR: 0.982 vs 0.946, P = .003), and (3) all knee pathologies reported lower scores on functional outcomes (79 vs 65 of 80 points in Lower-Extremity Functional Scale, P < .0001) and showed less quadriceps torque-generating capacity (10.7 vs 7.8 N·m/s/kg, P < .0001). Among the knee pathologies, patients with AKP showed less quadriceps voluntary activation compared with the patients with meniscus surgery (0.928 vs 0.964, P = .03). CONCLUSION As patients with AKP had an additional impairment in knee joint flexion replications and reported a less score in functional outcomes, knee pain may produce a greater impact on functional deficiency.
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Melo MDO, Pompeo KD, Baroni BM, Sonda FC, Vaz MA. Randomised study of the effects of neuromuscular electrical stimulation and low-level laser therapy on muscle activation and pain in patients with knee osteoarthritis. INTERNATIONAL JOURNAL OF THERAPY AND REHABILITATION 2019. [DOI: 10.12968/ijtr.2018.0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Background The combined effects of low-level laser therapy and neuromuscular electrical stimulation on knee osteoarthritis have yet to be analysed. This study aimed to determine the individual and combined effects of laser therapy and electrical stimulation on muscle activation and pain in older people with knee osteoarthritis. Methods A total of 45 women aged 60–75 years with knee osteoarthritis were randomised into three groups to receive stimulation, laser or stimulation plus laser therapy. All three groups underwent a 4-week control period (without intervention) followed by an 8-week intervention period. The effects of the interventions on muscle inhibition, electrical activity and pain were analysed. Findings There was a decrease in muscle inhibition (effect size ≥0.6) and a reduction in pain (effect size >1.2) in all three groups. All therapies generated an increase in electrical activity (effect size 0.1–0.5). Conclusions Laser alone or in combination with electrical stimulation promoted similar increases in muscle activation and pain relief.
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Affiliation(s)
- Mônica de Oliveira Melo
- Professor, Centre of Research into the Science and Art of Human Movement, University of Caxias do Sul, Caxias do Sul, Brazil
| | - Klauber Dalcero Pompeo
- PhD Student, Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Francesca Chaida Sonda
- PhD Student, Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Marco Aurélio Vaz
- PhD Student, Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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Lowe T, Dong XN. The Use of Hamstring Fatigue to Reduce Quadriceps Inhibition After Anterior Cruciate Ligament Reconstruction. Percept Mot Skills 2017; 125:81-92. [PMID: 29019442 DOI: 10.1177/0031512517735744] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Arthrogenic muscle inhibition, an inability to fully activate the quadriceps muscles, has been persistently observed after anterior cruciate ligament reconstruction (ACLr) surgery. Reductions in quadriceps activation may be partly due to the flexion reflex pathway, hamstrings activation, and reciprocal quadriceps inhibition. Since central fatigue has been shown to modify hamstring excitability and change the hamstring reflex response, hamstring fatigue might alleviate quadriceps muscle inhibition by counteracting the flexion reflex. In this study, nine young adult athletes (age: M = 19.9 years, SD = 1.7) with unilateral ACLr and nine control athletes (age: M = 24.0 years, SD = 2.4) with no previous history of knee injury performed tempo squats to induce fatigue. The ACLr group tended to use hamstrings for more hip flexion and trunk forward flexion than the control group. We assessed each participant's quadriceps inhibition through the central activation ratio (CAR), measured by twitch interpolation, before and after the induced fatigue. A mixed analysis of variance was used to examine the effect of fatigue on the CAR between pre- and post-fatigue and for both ACLr and control groups. The ACLr group showed significantly ( p = .010) greater CAR of the quadriceps post-fatigue ( M = 96.0%, SD = 7.6%) than pre-fatigue ( M = 81.2%, SD = 15.8%), while the control group showed no significant ( p = .969) pre-fatigue ( M = 96.9%, SD = 9.6%) and post-fatigue ( M = 97.0%, SD = 17.1%) differences. Thus, fatigue training may be used as a rehabilitation strategy to restore normal quadriceps function at the knee joint following ACL reconstruction by relaxing the hamstrings and overcoming quadriceps inhibition.
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Affiliation(s)
- Timothy Lowe
- 1 Department of Health and Kinesiology, The University of Texas at Tyler, TX, USA
| | - Xuanliang Neil Dong
- 1 Department of Health and Kinesiology, The University of Texas at Tyler, TX, USA
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Harkey MS, Luc-Harkey BA, Lepley AS, Grindstaff TL, Gribble P, Blackburn JT, Spang JT, Pietrosimone B. Persistent Muscle Inhibition after Anterior Cruciate Ligament Reconstruction: Role of Reflex Excitability. Med Sci Sports Exerc 2017; 48:2370-2377. [PMID: 27434085 DOI: 10.1249/mss.0000000000001046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Persistent voluntary quadriceps activation deficits are common after anterior cruciate ligament reconstruction (ACLR), but the direct causes are unclear. The primary purpose of this study was to determine whether spinal reflex excitability deficits are present in individuals with a history of ACLR, and secondarily to determine whether spinal reflex excitability predicts which individuals possess full voluntary quadriceps activation. METHODS One hundred and forty-seven individuals (74 healthy and 73 ACLR) participated in this cross-sectional case-control study. Quadriceps spinal reflex excitability was quantified using the Hoffmann reflex normalized to the maximal muscle response (H:M ratio). Voluntary quadriceps activation was evaluated with the burst superimposition technique and calculated via the central activation ratio (CAR). Separate 2 × 2 ANCOVA tests were used to compare between-limb and between-group differences for H:M ratio and CAR. A receiver operating characteristic curve was used to determine the accuracy of H:M ratio to predict if ACLR participants present with full voluntary activation (CAR ≥ 0.95). RESULTS The ACLR H:M ratio was not different between limbs or compared with the healthy group (P > 0.05). Although ACLR CAR was lower bilaterally compared with the healthy group (P < 0.001), it did not differ between limbs. The H:M ratio has poor accuracy for predicting which individuals exhibit full voluntary activation (receiver operating characteristic area under the curve = 0.52, 95% CI = 0.37,0.66; odds ratio = 2.2, 95% CI = 0.8, 5.9). CONCLUSIONS Spinal reflex excitability did not differ between limbs in individuals with ACLR or compared with healthy participants. The level of quadriceps spinal reflex excitability has poor accuracy at predicting which ACLR individuals would demonstrate full voluntary quadriceps activation.
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Affiliation(s)
- Matthew S Harkey
- 1Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC; 2Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC; 3Department of Kinesiology, University of Connecticut, Storrs, CT; 4Physical Therapy Department, Creighton University, Omaha, NE; 5Department of Rehabilitation Sciences, University of Kentucky, Lexington, KY; and 6Department of Orthopaedics, School of Medicine, University of North Carolina at Chapel Hill, NC
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Pamukoff DN, Pietrosimone BG, Ryan ED, Lee DR, Blackburn JT. Quadriceps Function and Hamstrings Co-Activation After Anterior Cruciate Ligament Reconstruction. J Athl Train 2017; 52:422-428. [PMID: 28388231 DOI: 10.4085/1062-6050-52.3.05] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
CONTEXT Individuals with anterior cruciate ligament reconstruction (ACLR) have quadriceps dysfunction that contributes to physical disability and posttraumatic knee osteoarthritis. Quadriceps function in the ACLR limb is commonly evaluated relative to the contralateral uninjured limb. Bilateral quadriceps dysfunction is common in individuals with ACLR, potentially biasing these evaluations. OBJECTIVE To compare quadriceps function between individuals with ACLR and uninjured control participants. DESIGN Cross-sectional study. SETTING Research laboratory. PATIENTS OR OTHER PARTICIPANTS Twenty individuals with unilateral ACLR (age = 21.1 ± 1.7 years, mass = 68.3 ± 14.9 kg, time since ACLR = 50.7 ± 21.3 months; females = 14; Tegner Score = 7.1 ± 0.3; 16 patellar tendon autografts, 3 hamstrings autografts, 1 allograft) matched to 20 control participants (age = 21.2 ± 1.2 years, mass = 67.9 ± 11.3 kg; females = 14; Tegner Score = 7.1 ± 0.4) on age, sex, body mass index, and Tegner Activity Scale. MAIN OUTCOME MEASURE(S) Maximal voluntary isometric knee extension was performed on an isokinetic dynamometer. Peak torque (PT), rate of torque development (RTD), electromyographic (EMG) amplitude, central activation ratio (CAR), and hamstrings EMG amplitude were assessed during maximal voluntary isometric knee extension and compared between groups using independent-samples t tests. Relationships between hamstrings co-activation and quadriceps function were assessed using Pearson correlations. RESULTS Participants with anterior cruciate ligament reconstruction displayed lesser quadriceps PT (1.86 ± 0.74 versus 2.56 ± 0.37 Nm/kg, P = .001), RTD (39.4 ± 18.7 versus 52.9 ± 16.4 Nm/s/kg, P = .03), EMG amplitude (0.25 ± 0.12 versus 0.37 ± 0.26 mV, P = .04), and CAR (83.3% ± 11.1% versus 93.7% ± 3.2%, P = .002) and greater hamstrings co-activation (27.2% ± 12.8% versus 14.3% ± 3.7%, P < .001) compared with control participants. Correlations were found between hamstrings co-activation and PT (r = -0.39, P = .007), RTD (r = -0.30, P = .03), and EMG amplitude (r = -0.30, P = .03). CONCLUSIONS Individuals with ACLR possessed deficits in PT, RTD, and CAR compared with control participants. Peak torque is the net result of all agonist and antagonist activity, and lesser PT in individuals with ACLR is partially attributable to greater hamstrings co-activation.
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Norte GE, Frye JL, Hart JM. Reliability of the Superimposed-Burst Technique in Patients With Patellofemoral Pain: A Technical Report. J Athl Train 2016; 50:1207-11. [PMID: 26636730 DOI: 10.4085/1062-6050-50.10.03] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT The superimposed-burst (SIB) technique is commonly used to quantify central activation failure after knee-joint injury, but its reliability has not been established in pathologic cohorts. OBJECTIVE To assess within-session and between-sessions reliability of the SIB technique in patients with patellofemoral pain. DESIGN Descriptive laboratory study. SETTING University laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 10 patients with self-reported patellofemoral pain (1 man, 9 women; age = 24.1 ± 3.8 years, height = 167.8 ± 15.2 cm, mass = 71.6 ± 17.5 kg) and 10 healthy control participants (3 men, 7 women; age = 27.4 ± 5.0 years, height = 173.5 ± 9.9 cm, mass = 78.2 ± 16.5 kg) volunteered. INTERVENTION(S) Participants were assessed at 6 intervals spanning 21 days. Intraclass correlation coefficients (ICCs [3,3]) were used to assess reliability. MAIN OUTCOME MEASURE(S) Quadriceps central activation ratio, knee-extension maximal voluntary isometric contraction force, and SIB force. RESULTS The quadriceps central activation ratio was highly reliable within session (ICC [3,3] = 0.97) and between sessions through day 21 (ICC [3,3] = 0.90-0.95). Acceptable reliability of knee extension (ICC [3,3] = 0.75-0.91) and SIB force (ICC [3,3] = 0.77-0.89) was observed through day 21. CONCLUSIONS The SIB technique was reliable for clinical research up to 21 days in patients with patellofemoral pain.
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Affiliation(s)
- Grant E Norte
- Department of Kinesiology, University of Virginia, Charlottesville
| | - Jamie L Frye
- Department of Health Sciences, James Madison University, Harrisonburg, VA
| | - Joseph M Hart
- Department of Kinesiology, University of Virginia, Charlottesville
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Luc BA, Harkey MH, Arguelles GD, Blackburn JT, Ryan ED, Pietrosimone B. Measuring voluntary quadriceps activation: Effect of visual feedback and stimulus delivery. J Electromyogr Kinesiol 2016; 26:73-81. [DOI: 10.1016/j.jelekin.2015.10.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 09/24/2015] [Accepted: 10/14/2015] [Indexed: 11/26/2022] Open
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Immediate Effects of Therapeutic Ultrasound on Quadriceps Spinal Reflex Excitability in Patients With Knee Injury. Arch Phys Med Rehabil 2015; 96:1591-8. [PMID: 25839089 DOI: 10.1016/j.apmr.2015.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/10/2015] [Accepted: 03/20/2015] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To investigate the effects of nonthermal therapeutic ultrasound on quadriceps spinal reflex excitability in patients with knee joint injury. DESIGN Double-blind, randomized controlled laboratory study with a pretest posttest design. SETTING University laboratory. PARTICIPANTS Recreationally active volunteers with a self-reported history of diagnosed intra-articular knee joint injury and documented quadriceps dysfunction (N=30). INTERVENTIONS A nonthermal ultrasound, or sham, treatment was applied to the anteromedial knee. MAIN OUTCOME MEASURES Hoffmann reflex measurements were recorded at baseline, immediately postintervention, and 20 minutes post-intervention. The peak Hoffmann reflex amplitude was normalized by the peak motor response (H/M ratio) measured from the vastus medialis using surface electromyography as an estimate of quadriceps motorneuron pool excitability. A repeated-measures analysis of variance was used for comparisons. RESULTS A significant group-by-time interaction was observed for mean (P=.016) and change (P=.044) in H/M ratio. The ultrasound group demonstrated significantly higher mean (P=.015) and change (P=.028) in H/M ratio 20 minutes postintervention than did the sham ultrasound group. CONCLUSIONS Quadriceps motoneuron pool excitability was facilitated 20 minutes after a nonthermal therapeutic ultrasound treatment, and not a sham treatment. These data provide supporting evidence of the contribution of peripheral receptors in modulation of the arthrogenic response in patients with persistent quadriceps dysfunction. Future research in this area should attempt to identify optimal treatment parameters and translate them to clinical outcomes.
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Norte GE, Kuenze C, Hart JM. Closed chain assessment of quadriceps activation using the superimposed burst technique. J Electromyogr Kinesiol 2014; 24:341-7. [PMID: 24731724 DOI: 10.1016/j.jelekin.2014.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 02/24/2014] [Accepted: 03/16/2014] [Indexed: 01/21/2023] Open
Abstract
UNLABELLED The superimposed burst technique is used to estimate quadriceps central activation ratio during a maximal voluntary isometric contraction, which is calculated from force data during an open-chain knee extension task. Assessing quadriceps activation in a closed-chain position would more closely simulate the action of the quadriceps during activity. Our aim was to determine the test-retest reliability of the quadriceps central activation ratio in the closed chain. METHODS Twenty-two healthy, active volunteers (13M/12F; age=23.8±3; height=72.7±14.5cm; mass=175.3±9.6kg) were recruited to participate. Knee extension MVIC torque and the peak torque during a superimposed electrical stimulus delivered to the quadriceps during an MVIC were measured to estimate quadriceps CAR. Interclass correlation coefficients were used to assess test-retest reliability between sessions, and Bland-Altman plots to graphically assess agreement between sessions. RESULTS Test-retest reliability was fair for CAR (ICC2,k=0.68; P=0.005), with a mean difference of -2.8±10.3%, and limits of agreement ranging -23.1-18.1%. CONCLUSIONS CAR calculated using the superimposed burst technique is moderately reliable in a closed-chain position using technique-based instruction. Although acceptable reliability was demonstrated, wide limits of agreement suggest high variability between sessions.
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Affiliation(s)
- Grant E Norte
- Department of Human Services, Kinesiology Program Area, University of Virginia, United States.
| | - Christopher Kuenze
- Department of Human Services, Kinesiology Program Area, University of Virginia, United States
| | - Joseph M Hart
- Department of Human Services, Kinesiology Program Area, University of Virginia, United States
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Logerstedt D, Lynch A, Axe MJ, Snyder-Mackler L. Pre-operative quadriceps strength predicts IKDC2000 scores 6 months after anterior cruciate ligament reconstruction. Knee 2013; 20:208-12. [PMID: 23022031 PMCID: PMC3535501 DOI: 10.1016/j.knee.2012.07.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 07/20/2012] [Accepted: 07/28/2012] [Indexed: 02/02/2023]
Abstract
BACKGROUND Quadriceps strength deficits are ubiquitous after anterior cruciate ligament (ACL) injury. Deficits prior to surgery can influence knee function post-operatively. Inhibition contributes to quadriceps strength deficits after an ACL injury. Body mass index, meniscal injury, and sex influence functional outcomes after ACL reconstruction. The purpose of this study is to examine the relationship of pre-operative quadriceps strength and post-operative knee function and to investigate how other pre-operative factors may influence this relationship. METHODS After an ACL injury, subjects received pre-operative rehabilitation and performed quadriceps strength testing. Subjects underwent reconstruction and post-operative rehabilitation. Six months after ACL reconstruction, subjects completed the International Knee Documentation Committee 2000 subjective form (IKDC2000). Linear regression models were developed using IKDC2000 scores at 6 months after ACL reconstruction as the dependent variable. RESULTS Fifty-five subjects had complete pre-operative data and IKDC2000 scores at 6 months after ACL reconstruction. Pre-operative involved quadriceps strength was a significant predictor for IKDC2000 scores 6 months after ACL reconstruction. Sex, meniscal injury, pre-operative BMI, and pre-operative involved quadriceps activation ratio were not significant predictors in the regression model. CONCLUSIONS Pre-operative quadriceps strength can predict IKDC2000 scores 6 months after ACL reconstruction. Deficits in pre-operative quadriceps strength influence self-reported function 6 months after surgery. Factors that are known to influence quadriceps strength and self-reported outcomes do not influence the relationship between pre-operative quadriceps strength and post-operative IKDC2000 scores.
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Affiliation(s)
- David Logerstedt
- Dept. of Physical Therapy, University of Delaware, 301 McKinly Lab, Newark, DE 19716 USA, Telephone: +1-302-831-8667, Fax: +1-302-831-4234,
| | - Andrew Lynch
- University of Pittsburgh Department of Orthopaedic Surgery, Pittsburgh, PA 15213 USA
| | - Michael J. Axe
- Medical Arts Pavilion I, 4745 Ogletown-Stanton Road, Suite 225, Newark, DE 19713 USA
| | - Lynn Snyder-Mackler
- Dept. of Physical Therapy, University of Delaware, 301 McKinly Lab, Newark, DE 19716 USA
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Abstract
OBJECTIVE To examine the immediate effects of experimentally induced anterior knee pain (AKP) on involuntary and voluntary quadriceps strength and activation. DESIGN Crossover 3 × 3 randomized controlled laboratory study with repeated measures. SETTING Human Performance Research Center, Brigham Young University. PARTICIPANTS Thirteen neurologically sound volunteers (age, 21.9 ± 3.2 years). INTERVENTIONS Subjects underwent 3 different conditions (pain, sham, and control). To induce AKP and sham condition, 5% sodium chloride and 0.9% sodium chloride (total volume of 1.0 mL for each condition), respectively, were injected into the infrapatellar fat pad on the dominant leg. No injection was performed for the control condition. MAIN OUTCOME MEASURES The vastus medialis peak Hoffmann reflex normalized by the peak motor response (H:M ratio) was used to measure involuntary quadriceps activation. Quadriceps central activation ratio (CAR) using maximal isometric knee extension torque (N·m) was calculated to assess voluntary quadriceps activation. The visual analog scale was used to measure pain perception. RESULTS Our pain model increased perceived pain immediately after the 5% hypertonic saline injection and pain lasted for 12 minutes on average (F40,743 = 16.85, P < 0.001). During the pain condition, subjects showed a 12% decrease in H:M ratio (F2,59 = 8.64, P < 0.001), a 34% decrease in maximal isometric knee extension torque (F2,59 = 5.89, P < 0.01), and a 5% decrease in CAR (F2,59 = 3.83, P = 0.03). CONCLUSIONS Our data showed that joint pain may be an independent factor to alter function of the muscles surrounding the painful joint. Both involuntary and voluntary inhibitory pathways may play a role in an immediate reduction of muscle activation.
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