RESUMO
OBJECTIVE: Underlying the ability of the hamstrings to decrease tibial anterior shear is the time of firing in comparison with the quadriceps. This timing may be aided by neural programming during a planned or expected activity. It is theorized that individuals who have better programming ability will suffer fewer anterior cruciate ligament (ACL) injuries due to joint protection through muscular stabilization. A component of this dynamic restraint is the development of muscular tension before the knee is loaded. The objective of our study was to compare the muscular activity before footstrike in ACL-deficient (ACL-D), ACL-reconstructed (ACL-R), and control (C) females during functional activities. DESIGN AND SETTING: Active females were divided into groups based on their ACL status. The study was conducted in a neuromuscular research laboratory. SUBJECTS: Twenty-four female subjects (ACL-D = 6, ACL-R = 12, C = 6). MEASUREMENTS: Integrated electromyographic (IEMG) activity from the thigh (vastus medialis obliquus [VMO], vastus lateralis [VL], medial hamstring, and lateral hamstring) and leg (medial gastrocnemius and lateral gastrocnemius [LG]) and footswitch signals were recorded during downhill walking (15 degrees at 0.92 m/s), running (2.08 m/s), hopping, and landing from a step (20.3 cm). IEMG activity was normalized to the mean amplitude of the sample and analyzed for area and mean amplitude for 150 milliseconds before heelstrike. Side-to-side differences were determined by t tests, and separate one-way analyses of variance (ANOVA) were used to detect differences among the 3 groups for each muscle of each activity. RESULTS: IEMG area side-to-side differences for the ACL-D group appeared in the LG (involved [I] = 36.4 +/- 19.7, uninvolved [U] = 60.1 +/- 23.6) during landing, in the VMO (I = 11.4 +/- 3.8, U = 7.2 +/- 3.1) and VL (I = 13.3 +/- 2.7, U = 8.9 +/- 1.9) during running, and in the VMO (I = 9.2 +/- 4.2, U = 19.5 +/- 7.3) during downhill walking. IEMG mean amplitude side-to-side differences for the ACL-D group appeared in the LG (I = 79.7 +/- 30.3, U = 122.3 +/- 34.9) during downhill walking and in the VMO (I = 78.6 +/- 23.2, U = 45.8 +/- 18.9) during the run; IEMG mean amplitude side-to-side differences for the ACL-R group appeared in the LG (I = 74.7 +/- 40.0, U = 52.8 +/- 14.3) during the hop. The ACL-D group had higher IEMG means than control in the VL (ACL-D = 12.9 +/- 5.8, C = 7.1 +/- 3.9), but lower in the VMO (ACL-D = 9.2 +/- 4.2, C = 15.7 +/- 3.6). CONCLUSIONS: The side-to-side differences of the ACL-D and ACL-R groups, as well as the group differences between ACL-D and control, suggest that different muscle activation strategies are used by females when performing different dynamic activities. Therefore, muscle unit differentiation may be the cause of our results. These changes appear to be reversed through surgery or the associated postoperative rehabilitation.
RESUMO
OBJECTIVE: The high incidence of noncontact anterior cruciate ligament (ACL) injuries in females has attracted research to investigate the capacity of muscles to reflexively protect the knee joint from capsuloligamentous injury. Numerous reflex pathways link mechanoreceptors in the ACL with contractile fibers in the quadriceps and hamstring muscles. Loads placed on the ACL modify reactive muscle activity through the feed-back process of neuromuscular control and are critical for dynamic muscular stabilization. Noncontact ACL injuries may be the result of aberrations in reactive muscle firing patterns. Therefore, compensatory muscle activation strategies must be employed if functional stability is to be restored after injury or surgical reconstruction. The purpose of our study was to compare the amplitude of reactive muscle activity in females with ACL-deficient (ACLD), ACL-reconstructed (ACLR), and control knees during functional activities. DESIGN AND SETTING: Female volunteer subjects were stratified into groups based on the status of their ACLs. Each subject performed 4 functional activities, bilaterally, during a single test session. SUBJECTS: Twenty-four female subjects participated in this study (ACLD = 6, ACLR = 12, control = 6). MEASUREMENTS: Integrated electromyographic (IEMG) data were collected with surface electrodes from the vastus medialis, vastus lateralis, medial hamstring, and lateral hamstring during downhill walking (15 degrees , 0.92 m/s), level running (2.08 m/s), and hopping and landing from a jump (20.3 cm). IEMG was normalized to the mean amplitude of 3 to 6 consecutive test repetitions. The mean area and peak IEMG of a 250-millisecond period after ground contact was used to represent reactive muscle activity. Side-to-side differences were determined using dependent t tests, and group differences were determined using a one-way analysis of variance. RESULTS: During running, the ACLD group demonstrated significantly greater area and peak IEMG activity in the medial hamstring in comparison with the ACLR group and greater peak activity in the lateral hamstring when compared with the control group. The ACLD group also demonstrated greater peak activity in the vastus medialis and a smaller area of IEMG activity in the lateral hamstring than the control group during running. During landing, the ACLD group demonstrated significantly less area of IEMG activity in the vastus lateralis when compared with the control group. No significant differences were identified between the ACLR and control groups, nor were side-to side differences revealed. CONCLUSIONS: Our results suggest that adaptations occur in the reactive muscle activity of ACLD females during functional activities. Strategies to minimize the anterior tibial translation in response to joint loading included increased hamstring activity and quadriceps inhibition. The reactive muscle activity exhibited in ACLD subjects is presumably an attempt to regain functional stability through the dynamic restraint mechanism. The absence of side-to-side differences suggests that these adaptations occur bilaterally after ACL injury.
RESUMO
The purpose of this study was to compare the single-incision, "endoscopic" (ENDO) anterior cruciate ligament (ACL) reconstruction technique with the two-incision, "rear-entry" technique (RE). Sixty patients were entered into a prospective study. Thirty patients underwent ACL reconstruction by the RE technique, followed by 30 consecutive patients using the ENDO procedure. Postoperatively all patients followed a standardized rehabilitation protocol. Follow-up evaluation consisted of a detailed physical examination, range of motion, thigh girth, vertical leap, hop test, KT-1000 testing, and patient interview. They were scored according to the International Knee Documentation Committee (IKDC) protocol, which takes objective and subjective data into account. Patients were also assessed for level of sports activity including frequency and type. Finally, anteroposterior and lateral x-ray films were evaluated with a scoring system for tunnel location. Of the initial 60 patients entered into the study, 50 were available for a detailed clinical and functional review (83%). Demographic comparisons revealed 24 RE patients and 26 ENDO patients. There were 16 men and 8 women in the RE group. The ENDO group comprised 16 men and 10 women. There were 14 right knees and 10 left knees in the RE group. In the ENDO group there were 13 right knees and 13 left knees. The average age in the RE group was 24 years and 25 years in the ENDO group. The average follow-up was 35 months (range 31-40 months) in the RE group and 29 months (range 24-35 months) in the ENDO group. Complications included two patients with loss of motion in the RE group and three in the ENDO group. There were no significant differences between the two groups tested with respect to the overall IKDC rating scale. Anteroposterior and lateral x-ray films revealed no significant differences in femoral and tibial tunnel placement. In conclusion, no significant functional or radiographic differences at a minimum 2-year follow-up could be identified when comparing the two ACL reconstructive techniques.
Assuntos
Ligamento Cruzado Anterior/cirurgia , Adulto , Artroscopia , Feminino , Seguimentos , Humanos , Masculino , Métodos , Estudos ProspectivosRESUMO
Though many anatomic and biomechanical studies have been performed to elucidate capsuloligamentous anatomy of the glenohumeral joint, no previous studies have evaluated capsuloligamentous anatomy during rotator cuff contraction. The purpose of this study was to define and document the orientation and interrelationship between the glenohumeral ligaments during simulated rotator cuff contraction. Six fresh cadaveric shoulders were arthroscoped to document and grade ligamentous anatomy. The superior and middle glenohumeral ligaments and the anterior and posterior bands of the inferior glenohumeral ligament complex were labeled by an arthroscopicassisted technique with a linked metallic bead system. Shoulders were then placed onto an experimental apparatus that simulated rotator cuff function through computer-controlled servo-hydrolic actuators attached to the rotator cuff and biceps by a clamp and cable-and-pulley system. Simulated rotator cuff action and manual placement allowed shoulders to be placed into three positions of rotation (neutral, internal, and external) in three positions of scapular plane abduction (0°, 45°, 90°). Anteroposterior and axillary lateral plane radiographs were taken in each position to document orientation of all four ligaments. Both the superior and middle glenohumeral ligaments were maximally lengthened in 0° and 45° abduction and external rotation and appeared to shorten in all positions of abduction. The anterior and posterior bands of the inferior glenohumeral ligament complex maintained a cruciate orientation in all positions of abduction in the anteroposterior plane, except at 90° abduction and external rotation, where they are parallel. This cruciate orientation is due to the different location of the glenoid origin and humeral insertion of each band and may allow reciprocal tightening of each during rotation. The glenohumeral capsule is composed of discreet ligaments that undergo large charges in orientation during rotation. The superior and middle glenohumeral ligaments appear to complement the inferior glenohumeral ligaments, with the former tightening in adduction and the latter tightening in abduction. This relationship permits the large range of motion normally seen in the glenohumeral joint.
RESUMO
There is a definite role for arthroscopy in the diagnosis and treatment of problem knees in children and adolescents. In this series, the largest reported to date, significant intraarticular pathology frequently existed in both preadolescent and adolescent groups. Three hundred ten knee arthroscopies in 285 children were reviewed. Preoperative clinical diagnoses were correlated with arthroscopic findings. In preadolescents (12 years old and younger), only 55% of preoperative clinical diagnoses were confirmed at surgery. Thirty-five percent of this group were found to have additional pathology not anticipated preoperatively. In adolescents (13 to 18 years old), 70% of clinical diagnoses were confirmed arthroscopically. Additional pathology was also found on arthroscopic examination in 25% of this group.