Internal Knee Abduction Moment Research Articles

Patellofemoral pain syndrome alters neuromuscular control and kinetics during stair ambulation

The aim of the study was to investigate differences in frontal plane knee kinetics, onset timing and duration of the gluteus medius (GMed), adductor longus (AL), and vastus medialis oblique (VMO) during stair ambulation between those with and without patellofemoral pain syndrome (PFPS). Twenty PFPS patients and twenty healthy participants completed stair ambulation while surface electromyography (EMG), video, and ground reaction forces were collected. PFPS patients had a higher peak internal knee abduction moment during stair ascent, and a higher internal knee abduction impulse for both ascent and descent. During stair ascent, PFPS patients displayed earlier onset of the AL and later onset of GMed, compared to the healthy individuals. Also, PFPS patients had longer activation duration of the AL and shorter activation durations of the VMO and GMed during stair ascent. During stair descent, PFPS patients displayed delayed GMed onset and shorter activation duration of GMed and VMO. The results of the study suggest that altered neuromuscular control of the medial thigh musculature may be an important contributor to PFPS.

The influence of sex and maturation on landing biomechanics: implications for anterior cruciate ligament injury

During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor the use of the knee extensors over the hip extensors to attenuate impact forces when compared with males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9-22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs 0.01±0.02 N m/kg m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs 1.4±0.1 N m/kg m; P<0.001) and knee/hip energy absorption ratios (2.9±0.1 vs 1.96±0.1 N m/kg m; P<0.001) compared with males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflect a biomechanical pattern that increases anterior cruciate ligament loading. This biomechanical strategy already was established in pre-pubertal female athletes.

Fatigue-Induced ACL Injury Risk Stems from a Degradation in Central Control

Fatigue contributes directly to anterior cruciate ligament (ACL) injury via promotion of high risk biomechanics. The potential for central fatigue to dominate this process, however, remains unclear. With centrally mediated movement behaviors being trainable, establishing this link seems critical for improved injury prevention. We thus determined whether fatigue-induced landing biomechanics were governed by a centrally fatiguing mechanism. Twenty female NCAA athletes had initial contact (IC) and peak stance (PS) three-dimensional hip and knee biomechanics quantified during anticipated and unanticipated single-leg landings, before and during unilateral fatigue accumulation. To induce fatigue, subjects performed repetitive (n = 3) single-leg squats and randomly ordered landings, until squats were no longer possible. Subject-based dependent factors were calculated across prefatigue trials and for those denoting 100%, 75%, 50%, and 25% fatigue and were submitted to three-way mixed-design analyses of covariance to test for decision, fatigue time, and limb effects. Fatigue produced significant (P < 0.01) decreases in IC knee flexion angle and PS knee flexion moment and increases in PS hip internal rotation and knee abduction angles and moments, with differences maintained from 50% fatigue through to maximum. Fatigue-induced increases in PS hip internal rotation angles and PS knee abduction angles and loads were also significantly (P < 0.01) greater during unanticipated landings. Apart from PS hip moments, significant limb differences in fatigued landing biomechanics were not observed. Unilateral fatigue induces a fatigue crossover to the contralateral limb during single-leg landings. Central fatigue thus seems to be a critical component of fatigue-induced sports landing strategies. Hence, targeted training of central control processes may be necessary to counter successfully the debilitative impact of fatigue on ACL injury risk.

Gait mechanics after ACL reconstruction: implications for the early onset of knee osteoarthritis

Background:Individuals who sustain a rupture of the anterior cruciate ligament (ACL) are at an increased risk for developing early-onset knee osteoarthritis (OA). The mechanism behind the early onset of the...

Gender Differences In Gait Mechanics Following an ACL Rupture: Implications For Early Onset Knee Osteoarthritis In Females

Females are 2-8 times as likely to sustain an ACL rupture compared to their male counterparts. In addition, females who have sustained an ACL rupture have been reported to exhibit signs of early knee OA progression. However the mechanism of the early knee OA development has not been fully examined. Medial compartment loads at the knee, as measured by the internal knee abduction moment, have been suggested to lead to knee OA progression. However this mechanism has not been examined in females following an ACL rupture. PURPOSE: To determine if females who have sustained an ACL rupture and subsequent repair exhibit altered gait mechanics that would suggest a more rapid progression of knee OA than males. METHODS: Five females, who had previously sustained an ACL rupture and subsequent repair in the past 10 years, volunteered to participate in the study. An age, activity level, and BMI matched male group, who also had a previous ACL rupture and repair within the last 10 years, was recruited for comparison. All participants completed a gait analysis at a selfselected intentional walking speed that allowed for calculation of frontal plane knee and hip joint angles and internal joint moments. Five trials were recorded and averaged to extract discrete variables in gait associated with knee OA progression. Due to the small sample size, effect size indices were performed to examine differences in the discrete variables between genders. All reported moments are internal. RESULTS: Large effect size indices (d>1.00) were apparent in the peak knee abduction moment, the peak knee adduction angle, knee adduction excursion, and the peak hip abduction moment. The peak knee abduction moment was 31% greater in the females compared to males (d=1.10). In addition, both peak knee adduction and knee adduction excursion were increased 49% and 52%, respectively, in the female group (d=1.23 and d=1.21). The peak hip abduction moment of the female group was 32.7% greater (d=1.54) compared to the male group. CONCLUSION: Females who have sustained an ACL rupture exhibit alterations in gait mechanics at the knee and hip joint suggesting they are at increased risk for early onset knee OA progression compared to ACL deficient males.

Impact of Fatigue on Gender-Based High-Risk Landing Strategies

Noncontact anterior cruciate ligament (ACL) injuries carry significant short- and long-term morbidity, particularly in females. To combat this epidemic, neuromuscular training has evolved aimed at modifying high-risk lower-limb biomechanics. However, injury rates and the gender disparity in these rates remain, suggesting that key components of the injury mechanism continue to be ignored. This study examined the potential contributions of neuromuscular fatigue to noncontact ACL injuries. Ten male and 10 female NCAA athletes had 3D lower-limb-joint kinematics and kinetics recorded during 10 drop jumps, both before and after fatigue. Mean subject-based initial-contact (N = 9) and peak stance-phase kinematic (N = 9) and normalized (mass x height) kinetic (N = 9) parameters were quantified before and after fatigue and submitted to a three-way ANOVA to determine for the main effects of leg, gender, and fatigue. A Bonferroni corrected alpha level of 0.002 was adopted for all statistical comparisons. Females landed with more initial ankle plantar flexion and peak-stance ankle supination, knee abduction, and knee internal rotation compared with men. They also had larger knee adduction, abduction, and internal rotation, and smaller ankle dorsiflexion moments. Fatigue increased initial and peak knee abduction and internal rotation motions and peak knee internal rotation, adduction, and abduction moments, with the latter being more pronounced in females. Fatigue-induced modifications in lower-limb control may increase the risk of noncontact ACL injury during landings. Gender dimorphic abduction loading in the presence of fatigue also may explain the increased injury risk in women. Understanding fatigue effects at both the central and peripheral levels will further afford elucidation of the ACL injury mechanism and, hence, more successful prevention strategies.

Hip and knee joint rotations differ between patients with medial and lateral knee osteoarthritis: Gait analysis of 30 patients and 15 controls

The motions and moments in the hip and knee in female patients on the waiting list for knee prosthesis surgery with medial (n = 15) or lateral (n = 15) osteoarthritis (OA) were compared with a control group (n = 15). We hypothesized that not only the kinematics and kinetics of the knee but also of the hip would differ between patients the medial and lateral groups. At midstance, patients with lateral OA showed slightly (2 degrees) more maximal (peak) adduction (p = 0.015) of the hip joint and patients with medial OA had 7 degrees more abduction (p < 0.001) than did controls. In patients with lateral OA, the femur was positioned in about 7 degrees more maximum external rotation (p = 0.001), but femur position did not differ between medial OA and controls (p > or = 0.8). There was a tendency to higher internal hip rotation moment in lateral OA compared to controls (p = 0.021). The maximum values of the internal knee abduction moments were 52% higher in medial OA (p = 0.005) and 63% lower in lateral OA (p < 0.001) compared to controls. Cases with medial OA had 9 degrees more, whereas those with lateral OA had 6 degrees less external tibial rotation than controls (medial vs. lateral OA, p = 0.001). We found an association between presence of lateral OA of the knee and the biomechanics of the hip joint. It remains to be evaluated if the changed biomechanics of the hip joint is a reason for development of lateral OA or an observation that is a result of this disease.

Effects of Childhood Obesity on Three-Dimensional Knee Joint Biomechanics During Walking

Despite the increasing percentages of children who are overweight, few studies have investigated their gait patterns. The purpose of this study was to quantify the three-dimensional knee joint kinematics and kinetics during walking in children of varying body mass and to identify effects associated with obesity. Three-dimensional kinematics and kinetics were collected from children of normal weight and overweight during normal gait using surface-mounted infrared emitting diodes and a force plate. The overweight group walked with a significantly lower peak knee flexion angle during early stance, and no significant differences in peak internal knee extension moments were found between groups. However, the overweight group showed a significantly higher peak internal knee abduction moment during early stance. These data suggest that although overweight children may develop a gait adaptation to maintain a similar knee extensor load, they may not be able to compensate for alterations in the frontal plane, which may lead to increased medial compartment joint loads. Therefore, assuming that the development of varus angular deformities of the knee joint and, in the longer term, medial compartment osteoarthritis are influenced by cumulative stress, this study supports the understanding that childhood obesity may impart a greater risk for the development of these diseases.