The aim of this study was to compare the muscular activity of knee stabilizers in different neuromuscular exercises in individuals with ACL reconstruction and nonlesioned
individuals. Eight males submitted to ACL reconstruction and eight nonlesioned males participated. The maximum voluntary isometric contraction (MVIC) of each muscle was
used for signal normalization. The electromyographic signal was quantified by the root mean square. The MVIC % between groups was different for extensor muscles of the
nonlesioned group, when compared to flexor muscles of the reconstructed group

Cardoso, Jefferson Rosa

dos Santos, Ana Beatriz Almeida Noronha

Jorge, Diogo Amaral

Nowotny, Alexandre Henrique

Pereira, Hugo Maxwell

Rabello, Lucas Nunes

English

ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive

  XXV ISBS Symposium 2007, Ouro Preto – Brazil                         226 ELECTROMYOGRAPHIC ACTIVITY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION DURING NEUROMUSCULAR EXERCISES Hugo Maxwell Pereira*, Jefferson Rosa Cardoso**,Alexandre Henrique Nowotny**, Ana Beatriz Almeida Noronha dos Santos**, Lucas Nunes Rabello**, Diogo Amaral Jorge**. *Universidade do Oeste de Santa Catarina. Joaçaba, SC, Brazil **Universidade Estadual de Londrina. Londrina, PR, Brazil The aim of this study was to compare the muscular activity of knee stabilizers in different neuromuscular exercises in individuals with ACL reconstruction and nonlesioned individuals. Eight males submitted to ACL reconstruction and eight nonlesioned males participated. The maximum voluntary isometric contraction (MVIC) of each muscle was used for signal normalization. The electromyographic signal was quantified by the root mean square. The MVIC % between groups was different for extensor muscles of the nonlesioned group, when compared to flexor muscles of the reconstructed group. KEY WORDS: Electromyography, ACL, Physical therapy techniques, Proprioception. INTRODUCTION: The anterior cruciate ligament (ACL) is one of most studied structures in biomechanics and rehabilitation. Its function is to provide tibialis anterior stability in relation to the femur and orient knee flexion and extension. Moreover, it limits knee hyperextension, performs constraint mechanisms and controls valgus and varus stress (Houck et al., 2005). In the USA, about 60.000 individuals with ACL injury are annually submitted to reconstruction surgery (Daniel et al., 1994). After ACL injury, functional deficits and joint instability occur. Secondarily, proprioception is affected by the loss of ligament mechanoreceptors. This loss can determine joint position sense reduction, leading to the aggravation of these dysfunctions (Barrett, 1991). The treatment goal after ACL reconstruction is to facilitate a return to functional activities through adequate programs that contain the following approaches: muscular force, flexibility, endurance, and neuromuscular reeducation. Moreover, protection of the reconstructed joint, a reduction in complications and the prevention of recurrences are also indicated (Feller et al., 2002). Neuromuscular reeducation training may enhance control of abnormal joint translation during functional activities by inducing compensatory alterations in muscle activity patterns (Risberg et al., 2001). The goal of this study was to compare the electric activity of the muscles that stabilize the knee in different neuromuscular exercises of individuals presenting ACL reconstruction and nonlesioned individuals. METHOD: Subjects: Eight males (aged⎯x = 31.8 ±7.0 years-old), submitted for ACL reconstruction (by central third patellar tendon autograft) more than 30 months prior to the study (⎯x = 34.8 ±13.7 months) and eight nonlesioned males (control group) (age⎯x = 32.0 ±7.3 years-old) participated in the study. Individuals presenting pain or swelling in the knee were excluded. Instrumentation and Procedure: The functional status of the subjects was assessed by the Single Hop for Distance test (Noyes et al 1991) and the Lysholm questionnaire (Peccin et al. 2006). An eight channel surface EMG system was used (EMG System do Brazil) to record the EMG signals. All raw EMG signals were bandpass filtered between 10 and 500 Hz, amplified (common mode rejection ratio >100 dB, overall gain 1000, noise <1 lV RMS) and analogue-to-digital converted (12-bit) at a sampling rate of 2000 Hz. The maximum voluntary isometric contraction (MVIC) of each muscle (vastus medialis obliquus (VMO), vastus lateralis (VL), semitendinosus, biceps femoris and medial gastrocnemius) was measured. After electrode positioning according to the SENIAM project, the neuromuscular exercise   XXV ISBS Symposium 2007, Ouro Preto – Brazil                                                                                  227order was randomized in such a way as to prevent bias due to individuals arriving fatigued at the last device. Participants were permitted a short training session prior to data collection.  One minute of electromyographic signal was collected, with the first and last ten seconds being discarded. It was understood that the forty remaining seconds are a reliable assessment of the muscular activity of neuromuscular training. The following devices were used (all in unipodal support and with 30° knee flexion) for the neuromuscular exercises: unipodal support on the ground, inclined plate, round plate, balancin, anterior-posterior and medium-lateral rollerboard direction.  The electromyographic signal was quantified by the root mean square (RMS), and normalized by the MVIC values.  Statistical analysis: The Student t test was used to analyze the demographic variables, since data estimates permitted its use. For the MVIC % values between groups, multivariate analysis of variance was used (MANOVA). For this, the homogeneity matrices and F test were first analyzed to verify differences between groups. Post-hoc was realized using the Bonferroni test. Significance was adopted at 5%. RESULTS: The demographic and morphological data of the individuals evaluated, with and without ACL injury, are presented in Table 1. No significant statistical difference in age or body mass was found between the groups.   Table 1. Morphological and Demographic Data  It was found a difference when compared extensor muscles of the control group when compared to flexor muscles of the reconstructed group for the same neuromuscular device (VMO or VL muscles of the control group in relation to the semitendinosus or biceps femoris of the reconstructed group). These differences appeared when the inclined plate (Table 2), round plate (Table 3), balancin (Table 4) and anterior-posterior rollerboard (Table 5) exercises were realized. During unipodal support on the ground and medium-lateral rollerboard direction no significant differences were found. In this type of comparison, the gastrocnemius muscle presented no significant difference in any device.  Table 2 - Mean ( x ) and Standard Deviation (SD) of MVIC % for inclined plate    Control Group   Vastus medialis obliquus ⎯x = 83.1; SD = 21.5 Vastus Lateralis  ⎯x = 82.5 ; SD = 17.0 Biceps Femoris ⎯x = 11.7; SD = 4.6 P = 0,026 P = 0,029  Reconstructed group  Semitendinosus ⎯x = 18.7; SD = 9.4 P = 0,001 P = 0,001         Recontruction group (n = 8)        Control group (n = 8)  x  (SD) Min - Max x  (SD)    Min - Max Age (years) 31.8 (7.0) 20.0 - 40.0 32.0 (7.3) 20.0 - 40.0 Body Mass (kg) 79.2 (12.6) 57.0 - 94.3     84.5 (12.2) 63.0 - 100.0 Height (m) 1.74 (0.11) 1.61 - 1.93     1.81 (0.06) 1.69 - 1.87   XXV ISBS Symposium 2007, Ouro Preto – Brazil                         228 Table 3 - Mean ( x ) and Standard Deviation (SD) of MVIC % for round plate    Control Group   Vastus medialis obliquus ⎯x = 87.7; SD 18.3 Vastus Lateralis  ⎯x = 89.5 SD = 15.6 Biceps Femoris ⎯x = 22.1; SD =5.7  P = 0,009 P = 0,006  Reconstructed group  Semitendinosus ⎯x = 38.7; SD =12.7 P = 0,001 P = 0,001  Table 4 - Mean ( x ) and Standard Deviation (SD) of MVIC % for Balancin    Control Group   Vastus medialis obliquus ⎯x = 85.9; SD = 14.4 Vastus Lateralis  ⎯x = 87.8 SD = 15.3 Biceps Femoris ⎯x = 18.0; SD = 7.5 P = 0,016 P = 0,001  Reconstructed group  Semitendinosus ⎯x = 21.1; SD = 9.5 P = 0,028 P = 0,001  Table 5 - Mean ( x ) and Standard Deviation (SD) of MVIC % for anterior-posterior rollerboard    Control Group   Vastus medialis obliquus ⎯x = 77.5; SD = 13.3 Vastus Lateralis  x = 77.5; SD = 13.3 Biceps Femoris ⎯x = 17.0; SD = 7.0 P = 0,019 P = 0,011  Reconstructed group  Semitendinosus ⎯x = 24.7; SD = 10.1 P = 0,001 P = 0,001 DISCUSSION: The initial hypothesis was that muscle electrical activities in different neuromuscular training exercises were equal when comparing individuals with surgical ligament reconstruction and the control group. Given the results, this hypothesis can only be rejected for the extensor muscles of the control group, when compared to the flexor muscle of the ligament reconstruction group. This could indicate a deficit of cocontraction between the flexor and extensor muscles. Fonseca et al. (2004) evaluate individuals presenting knee ligament injury without reconstruction submitted to conservative treatment while performing some neuromuscular exercise and suggest this co contraction. In the present study, RMS values were collected for 40 seconds, with minimal previous training. It is possible that after a single training program these values could be different. Barret et al. (1991) disclosed that knees with ACL injury presented proprioception deficits when compared to normal knees, however when the same authors analyzed a group that underwent ligament reconstruction and three months of neuromuscular training, they obtained results similar to a nonlesioned group. A review by Risberg et al. (2004) show that neuromuscular exercises present promising results; however, studies analyzing specific exercises are rare. When ligament reconstruction group muscles were analyzed, minor activation was verified during neuromuscular exercises when compared to the control group, indicating a recruitment deficit to perform exercises after a long postoperative period. This also occurred in a study by Fonseca et al. (2004), despite the difference in the sample evaluated, indicating a continued muscular recruitment necessity over a long period. Thus, it would seem that muscular balance is reached independent of the presence or absence of ligament surgery reconstruction.   XXV ISBS Symposium 2007, Ouro Preto – Brazil                                                                                  229Some authors investigated muscles adaptations after an ACL injury without reconstruction during closed kinetic chain exercises (Fitzgerald et al 2000). With the results of our study, reconstruction could also have caused some of these adaptations, such as imperfection in muscle cocontraction during neuromuscular exercises after ACL ligament reconstruction. Moreover, a global reduction motor recruitment in the post operated leg was found in relation to the control group. This result is in agreement with Heller and Pincivero (2003), regarding low activity in hamstrings, however they use different devices in comparison with this present study. CONCLUSION: In specific acute neuromuscular exercises, differences were observed when control group extensor muscles were compared to flexor muscles of the ACL reconstructed group when performing inclined, round plate, balancin and anterior-posterior roller-board. This could suggest a co contraction deficit even after an ACL reconstruction. REFERENCES: Houck J.R., Duncan A., de Haven K.E. (2005) Knee and hip angle and moment adaptations during cutting tasks in subjects with anterior cruciate ligament deficiency classified as noncopers. J Orthop Sports Phys Ther,35,531-540. Daniel D.M., Stone M.L., Dobson B.E., Fithian D.C., Rossman D.J., Kaufman K.R. (1994) Fate of the ACL-injured patient. A prospective outcome study. Am J Sports Med,22,632-644. Barrett D.S. (1991) Proprioception and function after anterior cruciate reconstruction. J Bone Joint Surg Br,73:833-837. Feller J.A., Cooper R., Webster K.E. (2002) Current Australian trends in rehabilitation following anterior cruciate ligament reconstruction. Knee, 9:121-126. Risberg M.A., Mork M., Holm I. (2001) Design and implementation of a neuromuscular training program following anterior cruciate ligament reconstruction; J Orthop Sports Phys Ther,  31,620-631 Noyes F.R., Barber S.D., Mangine R.E. (1991) Abnormal lower limb symmetry determined by function Hop tests after anterior cruciate ligament rupture. Am J Sports Med, 19:513-518. Peccin M.S., Ciconelli R., Cohen M. (2006) Questionário Específico para Sintomas do joelho,“Lysholm knee scoring scale“ – tradução e validação para a língua portuguesa. Acta Ortop Bras, 14,268-272 Fonseca S.T., Silva P.L.P., Ocarino J.M., Guimarães R.B., Oliveira M.T.C., Lage C.A. (2004) Analyses of dynamic co-contraction level in individuals with anterior cruciate ligament injury. J Electromyogr Kinesiol,14:239-247. Risberg M.A., Lewek M., Snyder-Mackler L. (2004) A systematic review of evidence for anterior cruciate ligament rehabilitation: how much and what type? Phys Ther Sport, 5:125-145. Fitzgerald G.K., Axe M.J., Snyder-Mackler L. (2000) The efficacy of perturbation training in nonoperative anterior cruciate ligament rehabilitation programs for physical active individuals. Phys Ther,80:128-140. Heller B.M., Pincivero D.M. (2003) The effect of ACL injury on lower extremity activation during closed kinetic chain exercise. 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ELECTROMYOGRAPHIC ACTIVITY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION DURING NEUROMUSCULAR EXERCISES

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ELECTROMYOGRAPHIC ACTIVITY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION DURING NEUROMUSCULAR EXERCISES

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