Electromechanical Delay of the Knee Flexor Muscles After Harvesting the Hamstrings for Anterior Cruciate Ligament Reconstruction

Objective: To investigate if harvesting of semitendinosus (ST) and gracilis for anterior cruciate ligament (ACL) reconstruction will have an effect in coordinative firing pattern of the hamstrings under fatigue. We hypothesized that fatigue will increase the electromechanical delay (EMD) of the hamstrings on the harvested site and impair the synchronization between the medial and lateral hamstrings, in terms of muscle activity onsets. Design: Prospective nonrandomized study. Setting: Institutional. Patients: Twelve ACL reconstructed patients with hamstrings, 2 years postoperatively. Interventions: The patients performed a fatigue protocol with 25 continuous maximal isometric voluntary contractions of 8-second duration with 2-second intervals. Main Outcome Measures: The electromyography activity of biceps femoris (BF) and ST was recorded bilaterally and simultaneously with the torque measurements. The dependent variable examined was the EMD difference between BF and ST (muscle activation pattern). Results: The fatigue protocol caused significant differences for the EMD values for both the intact and the reconstructed leg, demonstrating the influence of fatigue in EMD. However, the synchronization pattern between the medial and lateral hamstrings did not change significantly throughout the fatiguing protocol, revealing a balanced effect of fatigue. Conclusions: Although the EMD of ST and BF was significantly increased due to fatigue, as expected, their synchronization pattern as identified by the difference in their EMDs remained the same. Thus, the reconstructed knee responded in a balanced manner and the hamstrings firing pattern remained the same, despite the intervention to the ST tendon

Stride-to-stride variability is altered during backward walking in anterior cruciate ligament deficient patients

Background: Recently backward walking is used by physical therapists to strengthen the hamstring muscles and thus improve the function of the knee joint of anterior cruciate ligament deficient patients. The aim of this study was to examine the stride-to-stride variability of anterior cruciate ligament deficient patients during backward walking. The variation of how a motor behavior emerges in time is best captured by tools derived from nonlinear dynamics, for which the temporal sequence in a series of values is the facet of interest. Methods: Fifteen patients with unilateral anterior cruciate ligament deficiency and eleven healthy controls walked backwards at their self-selected speed on a treadmill while three-dimensional knee kinematics were collected (100 Hz). A nonlinear measure, the largest Lyapunov Exponent was calculated from the resulted knee joint flexion–extension data of both groups to assess the stride-to-stride variability. Findings: Both knees of the deficient patients exhibited significantly lower Lyapunov Exponent values as compared to the healthy control group revealing more rigid movement pattern. The intact knee of the deficient patients showed significantly lower Lyapunov Exponent values as compared to the deficient knee. Interpretation: Anterior cruciate ligament (ACL) deficiency leads to loss of optimal variability regardless of the walking direction (forwards in previous studies or backwards here) as compared to healthy individuals. This could imply diminished functional responsiveness to the environmental demands for both knees of ACL deficient patients which could result in the knees being more susceptible to injury

Hamstring-Dominant Strategy of the Bone–Patellar Tendon–Bone Graft Anterior Cruciate Ligament–Reconstructed Leg Versus Quadriceps-Dominant Strategy of the Contralateral Intact Leg During High-Intensity Exercise in Male Athletes

Purpose The purpose of this study was to investigate the effect of anterior cruciate ligament (ACL) reconstruction on the quadriceps-dominant strategy as a parameter associated with the neuromuscular control of the knee joint. Methods In this study 14 competitive soccer players who had undergone ACL reconstruction with bone–patellar tendon–bone autograft and 14 healthy competitive soccer players performed two 10-minute treadmill runs, 1 at moderate intensity and 1 at high intensity. Electromyographic recordings were acquired by use of a telemetric system at the third, fifth, seventh, and tenth minute of the runs from the vastus lateralis and the biceps femoris bilaterally. The dependent variable examined was the peak electromyographic amplitude during the stance phase. Analyses of variance were used to examine significant main effects and interactions. Results Vastus lateralis electromyographic activity during high-intensity running increased for both the control leg and intact leg (F = 4.48, P \u3c .01), whereas it remained unchanged for the reconstructed leg (P \u3e .05). Biceps femoris electromyographic activity during high-intensity running increased for the reconstructed leg only compared with both the control leg (F = 3.03, P \u3c .05) and intact leg (F = 3.36, P \u3c .03). Conclusions There is no presence of the quadriceps-dominant strategy in ACL-reconstructed athletes during moderate-intensity exercise. During high-intensity exercise, the intact contralateral leg develops the quadriceps-dominant strategy whereas the reconstructed leg does not. The reconstructed leg instead increases biceps femoris activity, developing a “hamstring-dominant” strategy, and this “asymmetry” may theoretically be in favor of the reconstructed knee. Level of Evidence Level III, retrospective comparative study

Knee braces can decrease tibial rotation during pivoting that occurs in high demanding activities

Purpose The purpose of this study was to investigate whether knee braces could effectively decrease tibial rotation during high demanding activities. Methods Using an in vivo three-dimensional kinematic analysis, 21 physically active, healthy, male subjects were evaluated. Each subject performed two tasks that were used extensively in the literature because they combine increased rotational and translational loads on the knee, (1) descending from a stair and subsequent pivoting and (2) landing from a platform and subsequent pivoting under three conditions: (A) wearing a prophylactic brace (braced), (B) wearing a patellofemoral brace (sleeved), and (C) unbraced condition. Results In the first task, tibial rotation during the pivoting phase was significantly decreased in the braced condition as compared to the sleeved condition (P = 0.019) and the non-braced condition (P = 0.002). In the second task, the same variable was significantly decreased in the braced condition as compared to the sleeved (P = 0.001) and the unbraced condition (P \u3c 0.001). The sleeved condition also produced significantly decreased tibial rotation with respect to the unbraced condition (P = 0.021). Conclusions Bracing decreased tibial rotation in activities where increased translational and rotational forces were applied. Because knee braces decreased tibial rotation, they can possibly be used with ACL-reconstructed and ACL-deficient patients to prevent such problems. Level of evidence Case–control study, Level III

Anatomical anterior cruciate ligament reconstruction: a prospective, clinical and biomechanical study

The rupture of the anterior cruciate ligament (ACL) of the knee results in anteroposterior and rotatory instability. The abnormally increased tibial rotation (TR) that remains pathological even after ACL reconstruction (ACLR) has been considered an important causative factor for future degenerative lesions of the articular cartilage of the knee joint. Recently the anatomical ACLR concept has been considered the best way to imitate the anatomy and function of the native ACL and to restore the function and the kinematic pattern of the knee joint. The purpose of the current PhD thesis was to introduce the new anatomic ACLR technique and to investigate the effectiveness regarding the knee joint function and kinematics. The patients of the study were prospectively evaluated after the anatomic single bundle (SB) ACLR that they underwent. The pearl points of this technique are: 1) The anatomic femoral tunnel placement low in the lateral femoral condyle correspondingly to the native ACL attachment site. 2) The anatomic placement of the tibial tunnel at about 5mm anterior and medially to the native ACL attachment so that the graft was finally positioned at the native ACL insertion. 3) External rotation of the graft before the fixation in the tibial tunnel in order to imitate native ACL fiber orientation, and 4) correction of the anterior subluxation and internal rotation of the tibia before the graft fixation. The examination of the patients included the clinical examination for anterior and rotary instability, the measurement of anterior tibial translation with the KT-1000 arthrometer, the TR measurement during high demanding pivoting tasks using 3 dimensional optoelectronic motion analysis system, knee joint function scores and assessment of the activity level of the patient. Magnetic resonance imaging was used to measure the graft obliquity and the change of the posterior cruciate ligament (PCL) shape which was quantified via the PCL index. The results of the studies of this PhD thesis showed that the SB anatomic ACLR : 1) Improves the obliquity of the ACL graft in the coronal plane, and this improvement correlates to better TR values. 2) Results into improved TR that correlates to better knee joint function postoperatively. 3) Restores the whole knee joint anatomy and this is reflected into the PCL index, so that more normal values of the PCL index correspond to better TR values for the patient during dynamic high demanding pivoting tasks. The anatomic SB ACLR imitates the anatomy of the native ACL by reproducing the native ACL attachment sites and the obliquity of the ACL. This is the reason that the anatomic SB ACLR restores the abnormally increased TR and improves the knee joint function.Η ρήξη του προσθίου χιαστού συνδέσμου (ΠΧΣ) του γόνατος οδηγεί σε προσθιοπίσθια και στροφική αστάθεια. Η παθολογικά αυξημένη κνημιαία στροφή (tibialrotation, TR) που έχει αποδειχθεί πως παραμένει μετά από συνδεσμοπλαστική ΠΧΣ (ΠΠΧΣ) θεωρείται βασικός αιτιολογικός παράγοντας για την μελλοντική ανάπτυξη εκφυλιστικών βλαβών του αρθρικού χόνδρου. Πρόσφατα υποστηρίζεται η άποψη πως η ανατομική ΠΠΧΣ με την προσομοίωση της ανατομικής και λειτουργίας του φυσικού ΠΧΣ είναι η ενδεδειγμένη τεχνική ΠΠΧΣ για βελτιστοποίηση της λειτουργικότητας και του κινηματικού προτύπου της άρθρωσης. Σκοπός της παρούσας διδακτορικής διατριβής είναι να παρουσιαστεί η νέα ανατομική ΠΠΧΣ με μόσχευμα μονής δέσμης και να αξιολογηθεί η αποτελεσματικότητά της στην λειτουργικότητα και το κινηματικό πρότυπο του γόνατος με έμφαση στην κνημιαία στροφή. Οι ασθενείς της μελέτης παρακολουθήθηκαν προοπτικά μετά την επέμβαση ανατομικής ΠΠΧΣ στην οποία υποβλήθηκαν από τον ίδιο χειρουργό. Τα βασικά στοιχεία της χειρουργικής τεχνικής είναι: 1) Η δημιουργία του οστικού αυλού χαμηλά στον έξω μηριαίο κόνδυλο, αντίστοιχα με το κέντρο της πρόσφυσης του φυσικού ΠΧΣ, 2) Η δημιουργία του οστικού αυλού στην κνήμη περίπου 5χιλ πρόσθια-έσω σε σχέση με το κέντρο του φυσικού ΠΧΣ, έτσι ώστε η θέση του μοσχεύματος να αντιστοιχεί στο κέντρο της πρόσφυσης του φυσικού ΠΧΣ, 3) Στροφή του μοσχεύματος πριν την σταθεροποίησή του στην κνήμη, προσομοιάζοντας της στροφή των ινών του φυσικού ΠΧΣ και 4) Διόρθωση της παθολογικής πρόσθιας ολίσθησης και έσω στροφής της κνήμης πριν την σταθεροποίηση του μοσχεύματος στην κνήμη. Η εξέταση των ασθενών περιελάμβανε κλινική εξέταση, μέτρηση της πρόσθιας κνημιαίας μετατόπισης με αρθρόμετρο, μέτρηση της TR σε δυναμικές δοκιμασίες υψηλής φόρτισης με οπτοηλεκτρονικό σύστημα τρισδιάστατης ανάλυσης κίνησης, κλίμακες καταγραφής της λειτουργικότητας της άρθρωσης και του επιπέδου αθλητικής δραστηριότητας του ασθενούς, και μαγνητική τομογραφία για την μέτρηση του προσανατολισμού του μοσχεύματος ΠΧΣ, και για τον προσδιορισμό της αλλαγής του σχήματος του οπισθίου χιαστού συνδέσμου (ΟΧΣ) και της ποσοτικοποίησης αυτής με τον δείκτη ΟΧΣ. Τα αποτελέσματα απέδειξαν πως η ανατομική ΠΠΧΣ με μόσχευμα μονής δέσμης: 1) βελτιώνει τον συνολικό προσανατολισμό του μοσχεύματος στο μετωπιαίο επίπεδο ο οποίος σχετίζεται με την διόρθωση της TR σε δυναμικές δοκιμασίες υψηλής φόρτισης, έτσι ώστε ένα πιο “λοξά” τοποθετημένο μόσχευμα ΠΧΣ να αντιστοιχεί σε βελτιωμένη TR. 2) Έχει ως αποτέλεσμα βελτιωμένη TR η οποία σχετίζεται με βελτιωμένη λειτουργικότητα της άρθρωσης μετεγχειρητικά. 3) Διορθώνει την συνολική ανατομική του γόνατος, το οποίο αντανακλάται στον δείκτη ΟΧΣ. Βελτιωμένες τιμές δείκτου ΟΧΣ αντιστοιχούν σε βελτιωμένη TR σε δυναμικές δοκιμασίες υψηλής έντασης. Με την τεχνική ανατομικής ΠΠΧΣ προσομοιάζεται η ανατομία του φυσικού ΠΧΣ, δηλαδή οι προσφύσεις στο μηριαίο οστό και την κνήμη και ο προσανατολισμός (λοξότητα) του μοσχεύματος, αποκαθίσταται η ανατομική του γόνατος, και διορθώνεται η παθολογική TR, οδηγώντας τελικά σε βελτιωμένη λειτουργικότητα της άρθρωσης

Kinematic predictors of subjective outcome after anterior cruciate ligament reconstruction: An in vivo motion analysis study

Purpose: The purpose of this study was to test whether rotational knee kinematics during dynamic pivoting activities are predictive of subjective functional outcome (IKDC, Lysholm), objective laxity scores (KT max), and activity levels (Tegner) in patients after anterior cruciate ligament reconstruction (ACLR). Methods: Thirty-one patients with single-bundle ACLR were evaluated prospectively with 3D-motion analysis during (1) descending a stairway and pivoting and (2) landing from a jump and pivoting. The side-to-side difference of tibial rotation range of motion (SSDTR) between the ACLR and the contralateral intact knee was calculated for the pivoting phase of each task. Linear regression models were applied with SSDTR, for each task predictors of the subjective IKDC score, Lysholm score, anterior tibial translation, and Tegner activity level. Results: SSDTR for descending and landing were predictive of the IKDC subjective score (R 2 = 0.46, p < 0.001 and R 2 = 0.40, p < 0.001, respectively) with "medium" effect sizes and of the Lysholm score (R 2 = 0.13, p < 0.05 and R 2 = 0.09, n. s.) with "small" to "none" effect sizes. SSDTR was not predictive of anterior translation or Tegner activity level (n. s.). Conclusions: Restoring rotational kinematics during dynamic pivoting activities after ACLR is predictive of functional outcome. The ability of the athlete after ACLR to control tibial rotation during pivoting activities may be predictive of functional outcome. Level of evidence: Case series study. Level IV. © 2012 Springer-Verlag