Neuromuscular Alterations After Ankle Sprains: An Animal Model to Establish Causal Links After Injury.

CONTEXT: The mechanisms that contribute to the development of chronic ankle instability are not understood. Investigators have developed a hypothetical model in which neuromuscular alterations that stem from damaged ankle ligaments are thought to affect periarticular and proximal muscle activity. However, the retrospective nature of these studies does not allow a causal link to be established. OBJECTIVE: To assess temporal alterations in the activity of 2 periarticular muscles of the rat ankle and 2 proximal muscles of the rat hind limb after an ankle sprain. DESIGN: Controlled laboratory study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Five healthy adult male Long Evans rats (age = 16 weeks, mass = 400.0 ± 13.5 g). INTERVENTION(S): Indwelling fine-wire electromyography (EMG) electrodes were implanted surgically into the biceps femoris, medial gastrocnemius, vastus lateralis, and tibialis anterior muscles of the rats. We recorded baseline EMG measurements while the rats walked on a motor-driven treadmill and then induced a closed lateral ankle sprain by overextending the lateral ankle ligaments. After ankle sprain, the rats were placed on the treadmill every 24 hours for 7 days, and we recorded postsprain EMG data. MAIN OUTCOME MEASURE(S): Onset time of muscle activity, phase duration, sample entropy, and minimal detectable change (MDC) were assessed and compared with baseline using 2-tailed dependent t tests. RESULTS: Compared with baseline, delayed onset time of muscle activity was exhibited in the biceps femoris (baseline = -16.7 ± 54.0 milliseconds [ms]) on day 0 (5.2 ± 64.1 ms; t4 = -4.655, P = .043) and tibialis anterior (baseline = 307.0 ± 64.2 ms) muscles on day 3 (362.5 ± 55.9 ms; t4 = -5.427, P = .03) and day 6 (357.3 ± 39.6 ms; t4 = -3.802, P = .02). Longer phase durations were observed for the vastus lateralis (baseline = 321.9 ± 92.6 ms) on day 3 (401.3 ± 101.2 ms; t3 = -4.001, P = .03), day 4 (404.1 ± 93.0 ms; t3 = -3.320, P = .048), and day 5 (364.6 ± 105.2 ms; t3 = -3.963, P = .03) and for the tibialis anterior (baseline = 103.9 ± 16.4 ms) on day 4 (154.9 ± 7.8 ms; t3 = -4.331, P = .050) and day 6 (141.9 ± 16.2 ms; t3 = -3.441, P = .03). After sprain, greater sample entropy was found for the vastus lateralis (baseline = 0.7 ± 0.3) on day 6 (0.9 ± 0.4; t4 = -3.481, P = .03) and day 7 (0.9 ± 0.3; t4 = -2.637, P = .050) and for the tibialis anterior (baseline = 0.6 ± 0.4) on day 4 (0.9 ± 0.5; t4 = -3.224, P = .03). The MDC analysis revealed increased sample entropy values for the vastus lateralis and tibialis anterior. CONCLUSIONS: Manually inducing an ankle sprain in a rat by overextending the lateral ankle ligaments altered the complexity of muscle-activation patterns, and the alterations exceeded the MDC of the baseline data.

Morphometric study and anatomical variations of the medial ligament of the talocrural joint / Estudio morfométrico y variaciones anatómicas del ligamento medial de la articulación talocrural

The aim of this study was to perform a descriptive study of the morphology, anatomical variations and morphometry of medial talocrural (or deltoid) ligament. We dissected 27 lower limbs obtained from amputations without histories of age, sex or disease. The measurements were made with a caliper, compass and ruler, expressing the results in millimeters. We described the superficial layer morphology of the medial ligament, measuring the size and ligament's thickness. For the deep layer we described and measured the length (l), width (w) and thickness (t). Results: Superficial layer: trapezoid form=66.7 percent (anterior margin=30.5 mm; posterior margin=27.6 mm; top margin=22.6 mm; bottom margin=50.5 mm), rectangular form=19 percent (anterior margin=19.3 mm; posterior margin=27.2 mm; top margin=24.4 mm; bottom margin=29.8 mm), triangular form=14.3 percent (anterior margin=37 mm; posterior margin=37.8 mm; bottom margin=48.3 mm). The average thickness of the superficial layer was 3.6 mm. Deep layer of the medial ligament: l=6.9 mm, w=11 mm, t=5.7 mm; presented rectangular form in 100 percent. In 76.2 percent of the specimens, the deep layer was covered completely by the superficial layer; however, in 23.8 percent the coverage is incomplete, showing the deep layer by posterior angle. The literature is contradictory regarding the anatomy and variations of the medial ligament of the ankle. There are important differences in morphology, attachments, subdivisions and relationships between the two layers of the deltoid ligament. Conclusions: We found significant anatomical variations in the morphology and the relationship between the superficial and deep layers of the deltoid ligament.

El objetivo fue realizar un estudio descriptivo de la morfología, variaciones anatómicas y la morfometría del ligamento talocrural medial (o deltoídeo). Se disecaron 27 miembros inferiores obtenidos de amputaciones sin antecedentes de edad, sexo, ni morbilidad. Las mediciones se realizaron con un pie de metro, regla y compás, expresando los resultados en milímetros. Se describió la morfología del ligamento medial en su capa superficial, midiendo el tamaño y grosor del ligamento. Para la capa profunda se describió y midió la longitud (l), ancho (a) y espesor (e). Resultados: En la capa superficial se observó: forma trapezoidal = 66,7 por ciento (margen anterior = 30,5 mm; margen posterior = 27,6 mm; margen superior = 22,6 mm; margen inferior = 50,5 mm), forma rectangular= 19 por ciento (margen anterior = 19,3 mm; margen posterior = 27,2 mm, margen superior = 24,4 mm; margen inferior = 29,8 mm), forma triangular = 14,3 por ciento (margen anterior=37 mm, margen posterior = 37,8 mm; margen inferior = 48,3 mm). El espesor promedio de la capa superficial fue de 3,6 mm. La capa profunda del ligamento medial: l = 6.9 mm, a = 11 mm, e = 5,7 mm, presentó forma rectangular en el 100 por ciento de los casos. En el 76,2 por ciento de las muestras, la capa profunda estaba completamente cubierta por la capa superficial, sin embargo, en 23,8 por ciento la cobertura fue incompleta, mostrando la capa profunda por el ángulo posterior. La literatura es contradictoria respecto a la anatomía y variaciones del ligamento medial del tobillo. Existen importantes diferencias en su morfología, inserciones, subdivisiones y las relaciones entre las dos capas del ligamento deltoídeo. Conclusiones: Se encontraron importantes variaciones anatómicas en la morfología y la relación entre las capas superficial y profunda del ligamento deltoídeo.

Inserción del tendón calcáneo / Insertion of the calcaneus tendon

El tendón calcáneo (TC) en el hombre es el más voluminoso y resistente del cuerpo, constituyéndose por su inserción en un elemento vital en la mecánica articular del pie como también en las numerosas patologías que afectan las regiones talocrural y calcánea. Para el estudio se utilizaron 120 miembros inferiores (60 derechos y 60 izquierdos), de cadáveres formolizados de individuos adultos, de ambos sexos. Se disecó la cara posterior de la pierna desde la línea articular de la rodilla hasta la parte inferior del calcáneo, se retiró el tejido adiposo precalcáneo dejando libre el TC. Se observó que el TC estaba formado, exclusivamente, por la fusión de las aponeurosis de los músculos gastrocnemio y sóleo en 62 casos (51,67 por ciento). El tendón del músculo plantar contribuye a la formación parcial del TC en 38 casos (31,67 por ciento) e integralmente en 20 casos (16,66 por ciento). El ancho del TC a nivel de la terminación del vientre del músculo sóleo fue de 12,88 mm +/- 2,0 en el hombre y de 11,55 mm +/- 1,6 en la mujer y el grosor del TC al mismo nivel de 4,29 mm +/- 0,64 en el hombre y de 4,36 mm +/- 0,64 en la mujer. El ancho del TC a nivel del margen posterosuperior del calcáneo fue de 17,98 mm +/- 1,7 en el hombre y de 17,06 mm +/- 1,53 en la mujer. El grosor del TC al mismo nivel fue de 3,79 mm +/- 0,61 en el hombre y de 3,93 mm /- 0,67 en la mujer. La distancia entre el margen posterosuperior del calcáneo y el inicio de la parte insertada del TC fue de 10,99 mm +/- 2,11 en el hombre y 10,84 +/- 2,71 en la mujer. El largo de la parte insertada del TC fue de 17,78 mm +/- 2,4 en el hombre y de 17,66 mm +/- 4,75 en la mujer. El ancho del TC a nivel de su inserción en el hueso calcáneo fue de 28,77 mm +/- 2,53 en el hombre y de 27,21 mm +/- 2,93 en la mujer. La tendinopatía en la inserción del TC suele ser frecuente requiriendo en algunos casos debridamiento quirúrgico del tendón. Por lo anterior, conocer aspectos morfométricos del TC y de su inserción adq...

In man the calaneous tendon (CT) is the most voluminous and resistent tendon in the body; its insertion is a vital element of the foot joint mechanism as well as in a number of disorders that affect talocrural and calcaneal regions. For the present study 120 lower members (60 right and 60 left) of formolized cadavers, adult subjects of both sexes were used. Posterior surface of the leg was disected from the joint line of the knee to the lower part of the calcaneal removing precalcaneus adipose tissue, exposing the CT. We observed that in 62 cases (51.67 percent) the CT was formed exclusively by fusion of aponeurosis of the gastrocnemius and soleus muscles. In 38 cases (31.67 percent) tendon of the plantar muscle contributes to the partial formation of the CT, and fully integrated in 20 cases (16.66 percent). Width of the CT at the soleus muscle belly end, was 12.88 mm +/- 2.0 in men and 11.55 mm +/- 1.6 women and density at the same level was 4.29 mm +/- 0.64 in men and 4.36 mm +/- 0.64 in women. Width of the CT at the posterosuperior border of the calcaneal was 17.98 mm +/- 17 in men, and 17.06 mm +/- 1.53 in women. CT density at the same level was 3.79 mm +/- 0.61 in men and 3.93 mm +/- 0.67 in women. Distance between posterosuperior border of the calcaneal and starting point of the inserted portion of the CT was 10.99 mm +/- 2.11 in men and 10.84 +/- 2.71 in women. Length of the inserted portion of the CT was 17.78 mm +/- 2.4 in men and 17.66 mm +/- 4.75 in women. Width of the CT at the insertion level in the calcaneus bone was 28.77 mm +/- 2.53 in men and 27.21 mm +/- 2.93 in women. Insertional CT tendinopathy is a chronic condition in some cases requiring surgical debridement of the tendon. Therefore, knowledge of morphological aspects of the CT and its insertion is important at the time of surgical procedures of the talocrural region.

Relaciones anatómicas de la vena safena magna con el nervio safeno a nivel talocrural / Anatomical relations of the saphenous magna vein with saphenous nerve at the talocrural level

La relación anatómica de la vena safena magna (VSM) y del nervio safeno (NS) en la región talocrural tiene importancia anatomoclínica, sin embargo existen pocos trabajos en la literatura anatómica. Se disecaron 30 pies de cadáveres formolizados de individuos adultos de ambos sexos, describiéndose el origen de la VSM y su relación con el NS en la región talocrural; se midió la distancia entre el NS y la VSM a nivel del ápice, margen anterior y a 1 cm del margen superior del maléolo medial. La VSM se originaba de la unión de la vena marginal medial del pie y el plexo venoso dorsal. La relación anatómica entre la VSM y el NS es variada, cursando el NS en un 63,3 por ciento anterior y 30 por ciento posterior a la VSM y en 6,7 por ciento el NS se dividía en dos ramos los cuales acompañaban anterior y posteriormente a la VSM. La distancia de la VSM y del NS al ápice del maléolo medial fue de 10,75 mm +/- 3,06 y 13,38 +/- 2,82 mm, respectivamente. La distancia de la VSM al margen anterior del maléolo medial fue de 0,53 mm +/- 0,51. Es importante conocer las relaciones de la VSM y del NS para su aplicación clínica, especialmente, en el momento de elegir un acceso venoso periférico no tan frecuente como las venas de la región talocrural.

Despite the clinical and anatomical significance of the anatomical relationship ofthesaphena magna vein (SMV)and thesaphenous nerve in (SN) in the talocrural region there are few studies in the literature. Thirty feet of adult formolized cadavers of both sexes were dissected describing the origin of the SMV and its relation with the SN in the talocrural region. Distance between the SN and the SMV was measured at the apex level, anterior margin and at 1 cm from the upper margin. The SMV originated from the medial marginal vein and dorsal venous arch. Anatomical relation between the SMV and the SN is varied, traveling anterior the SN 63.3 percent, and posterior the SMV 30 percent; in 6.7 percent the SN divided in two branches which joined anterior and posterior to the SMV. The distance of the SMV and the SN medial malleolus apex was 10.75mm +/- 3.06 and 13.38 +/- 2.82 mm. SMV distance to anterior margin of the medial malleolus was 0.53 mm +/- 0.51. The relation between the SMV and SN is important for clinicians particularly at the time of determining peripheral venous access not as frequent in veins of the talocrural region.

Effect of peripheral afferent alteration of the lateral ankle ligaments on dynamic stability.

BACKGROUND: The sensorimotor influence of the lateral ankle ligaments in muscle activation is unclear. HYPOTHESIS: The lateral ankle ligaments have significant sensorimotor influence on muscle activation. STUDY DESIGN: Controlled laboratory study. METHODS: Muscle-firing characteristics in response to a high-speed inversion perturbation and during gait were assessed in 13 normal subjects. Solutions (1.5% lidocaine or a placebo of saline) were injected bilaterally into the anterior talofibular and calcaneofibular ligaments (1.5 ml per ligament) to alter peripheral afferent influence. Subjects were again tested with the same protocol. RESULTS: The protective response of the anterior tibialis and peroneal muscles during inversion perturbation and mean muscle activation amplitude decreased during running after both injections. After injection, no significant differences were seen for muscle reflex latencies, maximum amplitude, time to maximum amplitude during inversion perturbation, or mean amplitude during walking. CONCLUSION: The lateral ankle ligaments have a sensorimotor influence on muscle activation. CLINICAL RELEVANCE: Induced edema from the injected solutions may have altered the sensorimotor influence of the lateral ankle ligaments, thereby inhibiting the dynamic ankle stabilizers. This finding suggests that dynamic stability may be compromised because of swelling after joint injury.

Mechanosensitive afferent units in the lateral ligament of the ankle.

We have studied the mechanosensitive afferent units in the lateral ligament of the ankle of the cat, with reference to the causes of lateral instability after injury, using electrophysiological recording from the lumbar dorsal rootlets. We identified 30 mechanosensitive units in the lateral ligament; 28 (93%) were located near the attachment to the fibula and calcaneus, which included both low-threshold group-II units and low- and high-threshold group-III units. Our results indicate that there are both proprioceptors and nociceptors in the lateral ligament of the cat ankle, and confirm that afferent fibres from the lateral ligament may contribute to the stability of the joint by regulation of position and movement.