Is structural and mild leg length discrepancy enough to cause a kinetic change in runners' gait?

Desigualdade de membros inferiores (DMI) está presente em cerca de 70% da população geral, podendo ser do tipo estrutural onde existe diferença no comprimento de estruturas ósseas, ou funcional, como resultado de alterações mecânicas dos membros inferiores. A desigualdade pode ainda ser classificada quanto a sua magnitude, sendo discreta, moderada, ou grave. As desigualdades discretas têm sido associadas especificamente à fratura por estresse, dor lombar e osteoartrite, e quando uma desigualdade está presente em indivíduos cuja sobrecarga mecânica é acentuada pela sua prática profissional, diária ou recreativa, estas alterações ortopédicas podem se manifestar precoce e gravemente. O objetivo deste estudo foi analisar e comparar a força reação do solo (FRS) durante a marcha de corredores com e sem DMI discreta. Os resultados mostraram que os sujeitos com desigualdades de 0,5 a 2,0 cm apresentaram no membro menor maiores valores da força vertical mínima (0,57 ± 0,07 PC) em relação ao membro maior (0,56 ± 0,08 PC). Logo, sujeitos com DMI discreta adotam mecanismos compensatórios capazes de gerar sobrecarga adicional ao sistema musculoesquelético para promover uma marcha simétrica como demonstrado pelos valores do Índice de Simetria Absoluto das variáveis da FRS vertical e horizontal.Leg length discrepancy (LLD) affects about 70% of the general population, and can be either structural - when the difference occurs in bone structures - or functional, because of mechanical changes at the lower limbs. The discrepancy can be also classified by its magnitude into mild, intermediate, or severe. Mild LLD has been particularly associated with stress fracture, low back pain and osteoarthritis, and when the discrepancy occurs in subjects whose mechanical loads are increased by their professional, daily or recreational activities, these orthopaedic changes may appear early and severely. The aim of this study was to analyze and compare ground reaction force (GRF) during gait in runners with and without mild LLD. Results showed that subjects with mild LLD of 0.5 to 2.0 cm presented higher values of minimum vertical GRF (0.57 ± 0.07 BW) at the shorter limb compared to the longer limb (0.56 ± 0.08 BW) Therefore, subjects with mild LLD adopt compensatory mechanisms that cause additional overloads to the musculoskeletal system in order to promote a symmetrical gait pattern as showed by the values of absolute symmetric index of vertical and horizontal GRF variables.FAPES

DOES MILD LEG LENGTH INEQUALITY AFFECT PLANTAR PRESSURE DISTRIBUTION DURING RUNNING?

The aim of this study was to investigate if a mild LLI altered plantar pressure distribution during running at approximately 12Km/h. Nowadays running can be considered one of the most important recreational activities, and mild leg length inequality (LLI), which appears to be usual among runners, has been related to running injuries. The hypothesis was that runners with mild LLI would present smaller values of plantar pressure at the lateral heel, and greater values at the medial midfoot at the long limb; and greater values at the lateral heel and lateral midfoot at the short limb in comparison with runners without LLI. Plantar pressure distribution was acquired using Pedar X mobile System. Measurements were performed under the feet of 14 runners distributed in two groups: control (LLI1.0cm). Contradicting the initial hypothesis, results demonstrated that runners with a mild LLI did not present significant differences in plantar pressure distribution in comparison to subjects without LLI, and between long and short limbs. These findings point out that analysis of plantar pressure distribution was not an efficient method for detecting small asymmetries or possible adjusts in lower limbs during running

VERTICAL GROUND REACTION FORCES AND EMG DURING LANDING IN FUNCTIONALLY UNSTABLE ANKLE

The purpose of this study was to compare vertical ground reaction forces (GRF) and electromyographic activity (EMG) from peroneus longus (PL), tibialis anterior (TA) and gastrocnemius lateralis (GL) of volleyball athletes with and without functional ankle instability (FI) during landing after a blocking maneuver. Synchronized EMG and GRF from 200ms prior to impact to 200ms after impact were acquired for 21 athletes with FI and 19 healthy ones. Results showed that FI subjects have a muscle activity that predisposes them to ankle sprains since PL presented lower RMS values prior to landing. GRFs were not different between groups

CHARACTERISTICS OF THE PATELLAR TENDONS IN ANTERIOR CRUCIATE LIGAMENT INJURED ATHLETES

The purpose of this study was to demonstrate the characteristics of patellar tendons and the quadriceps strength of athletes with anterior cruciate ligament reconstruction (ACLR) throughout rehabilitation. Athletes of different sports (n=27) had both patellar tendons (PT) assessed with ultrasound tissue characterization (UTC) method, and bilateral isokinetic quadriceps strength quantified in intervals of 1.5 months over their rehabilitation period. Reduction in the quality of the involved PT was observed after ACLR surgery, with these values returning to baseline at approximately 7.5 months post surgery. The uninvolved PT displayed no significant differences. Despite the increase in quadriceps strength, no statistical relevance was observed. ACLR caused reduction in the quality of the involved PT which might be correlated with tendon symptoms during the rehabilitation

Comparative anthropometry and biomechanics of locomotion in runners with and without structural leg length discrepancy

Existe uma alta incidência de desigualdade de membros inferiores na população geral, podendo ser do tipo estrutural, onde existe diferença no comprimento de estruturas ósseas, ou funcional, como resultado de alterações mecânicas dos membros inferiores (MMII). A desigualdade pode ainda ser classificada quanto a sua magnitude, sendo discreta, moderada, ou grave. São muitos os métodos antropométricos utilizados para avaliar a desigualdade, entre os mais usados estão os métodos clínicos, como o uso de fita métrica para medir a distância entre duas saliências ósseas. Além destes, os métodos radiográficos também podem ser usados, porém com menor freqüência devido ao custo elevado e exposição à radiação. As desigualdades discretas têm sido associadas especificamente à fratura por estresse, dor lombar e osteoartrite. Quando uma desigualdade está presente em indivíduos cuja sobrecarga mecânica é acentuada pela sua prática profissional, diária ou recreativa, estas desordens podem se manifestar precoce e gravemente. O objetivo deste estudo foi comparar diversas medidas antropométricas de comprimento de MMII usadas na prática clínica com a escanometria em corredores, e estudar a Força Reação do Solo durante a marcha e a corrida de corredores com desigualdade estrutural discreta de membros inferiores. Observou-se que a presença de desigualdade de membros inferiores foi associada à maior incidência de sintomas nos quadris e joelhos nos corredores. As medidas clínicas EIAS/MM (R=0,96; p=0,000), EIAS/ML (R=0,97; p=0,000), Crista/MM (R=0,95; p=0,000) e Umbigo/MM (R=0,92; p=0,000) apresentaram alta correlação com a escanometria. Entretanto, somente a medida clínica Umbigo/MM (0,8 ± 0,6 cm; 0,8 ± 0,5%) detectou desigualdade absoluta e normalizada entre os membros semelhante à escanometria (0,6 ± 0,5 cm; 0,8 ± 0,6%). Observou-se que quanto maior a desigualdade, maior a sobrecarga em ambos MMII, cargas estas capazes de causar em longo prazo desordens ortopédicas. Os sujeitos com desigualdade de 0,5 a 2,0 cm, durante o andar, apresentaram no MI menor maiores valores de Fzmin (0,56 ± 0,08 PC); e maiores valores de Fz2 e PO no MI menor durante o correr (2,48 ± 0,22 PC; 17,18 ± 3,35 PC/s). E os sujeitos com desigualdade de 1,0 a 2,2 cm apresentaram no MI maior uma menor Taxa de Crescimento 1 (9,19 ± 1,49 PC/s) em comparação ao controle (10,44 ± 1,72 PC/s) durante o andar; maiores valores de Fz1 no MI maior (1,70 ± 0,17 PC) em relação ao controle (1,57 ± 0,16PC), e ainda maiores valores de Fz2 e PO no MI menor (2,55 ± 0,22 PC; 17,07 ± 3,31 PC/s) durante o correr. No entanto, os sujeitos com desigualdade discreta de membros inferiores apresentaram a marcha e a corrida simétricas de acordo com os valores obtidos pelo Índice de Simetria Absoluto das variáveis da FRS vertical e horizontal.There is a high incidence of leg length discrepancy (LLD) in general population, which could be structural, when the difference occurs in bone structures, or functional, as a result of mechanical changes at the lower limbs. The discrepancy can also be classified by its magnitude, being mild, intermediate, or severe. Many anthropometric methods are used to evaluate discrepancy, however the most common are clinical methods, which use a tape to measure the distance between two bone landmarks. Radiographic methods can also be used, although they are characterized by high cost and radiation exposure. Mild LLD has been associated with stress fractures, lower back pain and osteoarthritis. When the discrepancy occurs in subjects whose mechanical loads are increased by their professional, daily or recreational activities, these disorders might appear early and severely. The aim of this study was to compare several anthropometric measurements of LLD used in clinical practice with the scanogram in runners, and to study the ground reaction forces during gait and running in runners with mild and structural LLD. Results demonstrated an association between LLD and higher incidence of symptoms in runners\' hips and knees. Clinical measures ASIS/MM (R=0.96; p=0.000), ASIS/LM (R=0.97; p=0.000), Crest/MM (R=0.95; p=0.000) and Umbilicus/MM (R=0.92; p=0.000) presented high correlation with scanogram. Although, only the clinical measurement Umbilicus/MM (0.8 ± 0.6 cm; 0.8 ± 0.5%) detected absolute and relative discrepancy between lower limbs similar to that detected with scanogram (0.6 ± 0.5 cm; 0.8 ± 0.6%). Results also showed that increasing discrepancy leads to overloads in both lower limbs, which may lead to orthopedic disorders after extended periods. Subjects with mild LLD of 0.5 to 2.0 cm presented higher values of Fzmin (0.56 ± 0.08 BW) at the shorter limb during gait, and higher values of Fz2 and PO at the shorter limb (2.48 ± 0.22 BW; 17.18 ± 3.35 BW/s) during running. Subjects with mild discrepancy of 1.0 to 2.2 cm presented a smaller rate of load 1 (9.19 ± 1.49 BW/s) at the longer limb during gait in comparison to control subjects (10.44 ± 1.72 BW/s), and higher values of Fz1 at the longer limb during running (1.70 ± 0,17BW ) relative to control subjects (1.57 ± 0.16PC). Subjects with mild discrepancy also showed higher values of Fz2 and PO at the shorter limb (2.55 ± 0.22 BW; 17.07 ± 3.31 BW/s). Nevertheless, subjects with mild LLD displayed symmetrical gait and running according to values obtained by Absolute Symmetric Index of vertical and horizontal GRF variables

Comparative anthropometry and biomechanics of locomotion in runners with and without structural leg length discrepancy

Existe uma alta incidência de desigualdade de membros inferiores na população geral, podendo ser do tipo estrutural, onde existe diferença no comprimento de estruturas ósseas, ou funcional, como resultado de alterações mecânicas dos membros inferiores (MMII). A desigualdade pode ainda ser classificada quanto a sua magnitude, sendo discreta, moderada, ou grave. São muitos os métodos antropométricos utilizados para avaliar a desigualdade, entre os mais usados estão os métodos clínicos, como o uso de fita métrica para medir a distância entre duas saliências ósseas. Além destes, os métodos radiográficos também podem ser usados, porém com menor freqüência devido ao custo elevado e exposição à radiação. As desigualdades discretas têm sido associadas especificamente à fratura por estresse, dor lombar e osteoartrite. Quando uma desigualdade está presente em indivíduos cuja sobrecarga mecânica é acentuada pela sua prática profissional, diária ou recreativa, estas desordens podem se manifestar precoce e gravemente. O objetivo deste estudo foi comparar diversas medidas antropométricas de comprimento de MMII usadas na prática clínica com a escanometria em corredores, e estudar a Força Reação do Solo durante a marcha e a corrida de corredores com desigualdade estrutural discreta de membros inferiores. Observou-se que a presença de desigualdade de membros inferiores foi associada à maior incidência de sintomas nos quadris e joelhos nos corredores. As medidas clínicas EIAS/MM (R=0,96; p=0,000), EIAS/ML (R=0,97; p=0,000), Crista/MM (R=0,95; p=0,000) e Umbigo/MM (R=0,92; p=0,000) apresentaram alta correlação com a escanometria. Entretanto, somente a medida clínica Umbigo/MM (0,8 ± 0,6 cm; 0,8 ± 0,5%) detectou desigualdade absoluta e normalizada entre os membros semelhante à escanometria (0,6 ± 0,5 cm; 0,8 ± 0,6%). Observou-se que quanto maior a desigualdade, maior a sobrecarga em ambos MMII, cargas estas capazes de causar em longo prazo desordens ortopédicas. Os sujeitos com desigualdade de 0,5 a 2,0 cm, durante o andar, apresentaram no MI menor maiores valores de Fzmin (0,56 ± 0,08 PC); e maiores valores de Fz2 e PO no MI menor durante o correr (2,48 ± 0,22 PC; 17,18 ± 3,35 PC/s). E os sujeitos com desigualdade de 1,0 a 2,2 cm apresentaram no MI maior uma menor Taxa de Crescimento 1 (9,19 ± 1,49 PC/s) em comparação ao controle (10,44 ± 1,72 PC/s) durante o andar; maiores valores de Fz1 no MI maior (1,70 ± 0,17 PC) em relação ao controle (1,57 ± 0,16PC), e ainda maiores valores de Fz2 e PO no MI menor (2,55 ± 0,22 PC; 17,07 ± 3,31 PC/s) durante o correr. No entanto, os sujeitos com desigualdade discreta de membros inferiores apresentaram a marcha e a corrida simétricas de acordo com os valores obtidos pelo Índice de Simetria Absoluto das variáveis da FRS vertical e horizontal.There is a high incidence of leg length discrepancy (LLD) in general population, which could be structural, when the difference occurs in bone structures, or functional, as a result of mechanical changes at the lower limbs. The discrepancy can also be classified by its magnitude, being mild, intermediate, or severe. Many anthropometric methods are used to evaluate discrepancy, however the most common are clinical methods, which use a tape to measure the distance between two bone landmarks. Radiographic methods can also be used, although they are characterized by high cost and radiation exposure. Mild LLD has been associated with stress fractures, lower back pain and osteoarthritis. When the discrepancy occurs in subjects whose mechanical loads are increased by their professional, daily or recreational activities, these disorders might appear early and severely. The aim of this study was to compare several anthropometric measurements of LLD used in clinical practice with the scanogram in runners, and to study the ground reaction forces during gait and running in runners with mild and structural LLD. Results demonstrated an association between LLD and higher incidence of symptoms in runners\' hips and knees. Clinical measures ASIS/MM (R=0.96; p=0.000), ASIS/LM (R=0.97; p=0.000), Crest/MM (R=0.95; p=0.000) and Umbilicus/MM (R=0.92; p=0.000) presented high correlation with scanogram. Although, only the clinical measurement Umbilicus/MM (0.8 ± 0.6 cm; 0.8 ± 0.5%) detected absolute and relative discrepancy between lower limbs similar to that detected with scanogram (0.6 ± 0.5 cm; 0.8 ± 0.6%). Results also showed that increasing discrepancy leads to overloads in both lower limbs, which may lead to orthopedic disorders after extended periods. Subjects with mild LLD of 0.5 to 2.0 cm presented higher values of Fzmin (0.56 ± 0.08 BW) at the shorter limb during gait, and higher values of Fz2 and PO at the shorter limb (2.48 ± 0.22 BW; 17.18 ± 3.35 BW/s) during running. Subjects with mild discrepancy of 1.0 to 2.2 cm presented a smaller rate of load 1 (9.19 ± 1.49 BW/s) at the longer limb during gait in comparison to control subjects (10.44 ± 1.72 BW/s), and higher values of Fz1 at the longer limb during running (1.70 ± 0,17BW ) relative to control subjects (1.57 ± 0.16PC). Subjects with mild discrepancy also showed higher values of Fz2 and PO at the shorter limb (2.55 ± 0.22 BW; 17.07 ± 3.31 BW/s). Nevertheless, subjects with mild LLD displayed symmetrical gait and running according to values obtained by Absolute Symmetric Index of vertical and horizontal GRF variables