Scott C. Landry

Neuromuscular and Lower Limb Biomechanical Differences Exist Between Male and Female Elite Adolescent Soccer Players During an Unanticipated Run and Crosscut Maneuver

Background Female athletes are 2 to 8 times more likely than male athletes to injure the anterior cruciate ligament during a noncontact athletic maneuver. Identifying anterior cruciate ligament injury risk factors in female athletes may help with the development of preventive training programs aimed at reducing injury rates. Hypothesis Differences between genders in lower limb kinematics, kinetics, and neuromuscular patterns will be identified in an adolescent soccer population during an unanticipated side-cut maneuver. Study Design Controlled laboratory study. Methods Forty-two elite adolescent soccer players (21 male and 21 female) performed an unanticipated side-cut maneuver, with the 3-dimensional kinematic, kinetic, and electromyographic lower limb data being analyzed using principal component analysis. Results The female athletes had higher gastrocnemius activity, normalized to maximal voluntary isometric contractions, and a mediolateral gastrocnemius activation imbalance that was not present in the male athletes during early stance to midstance of the side-cut. Female athletes demonstrated greater rectus femoris muscle activity throughout stance, and the only hamstring difference identified was a mediolateral activation imbalance in male athletes only. Female athletes performed the side-cut with less hip flexion and more hip external rotation and also generated a smaller hip flexion moment compared with the male athletes. Conclusion This is the first study to identify gender-related differences in gastrocnemius muscle activity during an unanticipated cutting maneuver. Clinical Relevance The increased and imbalanced gastrocnemius muscle activity, combined with increased rectus femoris muscle activity and reduced hip flexion angles and moments in female subjects, may all have important contributing roles in the higher noncontact ACL injury rates observed in female athletes.

Comparative fixation of tibial plateau fractures using alpha-BSM, a calcium phosphate cement, versus cancellous bone graft.

Objectives: To compare the compressive strength of a bone substitute material (α-BSM™) to cancellous bone when used to fill a defect void in a cadaver model of a Schatzker II split depression fracture of the lateral tibial plateau. Design: Randomized, paired design. Setting: Biomedical engineering laboratory. Patients: Twenty-six human tibias were harvested from 13 cadavers. Three pairs of tibia fractured during preparation and were excluded. The remaining 10 matched pairs were randomized to fixation by using the bone substitute material or cancellous bone. Intervention: A split depression fracture of the lateral tibial plateau was created in each tibia by using reproducible methods. This fracture was stabilized with a stainless steel L-plate and screws and either α-BSM™ or cancellous bone to fill the defect void. Main Outcome Measurements: Stiffness of the elevated fragment in compression, total depression of the joint at 1000 N. Results: The α-BSM™ bone substitute displayed significantly greater stiffness than cancellous bone constructs in Schatzker II split depression fractures of the lateral tibial plateau (P < 0.0001). Plateau defects displaced significantly less at 1000N when using α-BSM™ in comparison to cancellous bone (P < 0.0001). Conclusions: In this cadaveric study, α-BSM™ is an effective bone substitute compared with cancellous bone graft for stabilizing split depression fractures of the lateral tibial plateau.

Gender differences exist in neuromuscular control patterns during the pre-contact and early stance phase of an unanticipated side-cut and cross-cut maneuver in 15-18 years old adolescent soccer players

Non-contact ACL injuries generally occur as the foot contacts the ground during cutting or landing maneuvers and the non-contact ACL injury rate is 2-8 times greater in females compared to males. To provide insight into the gender bias of this injury, this study set out to identify gender differences in the neuromuscular response of the quadriceps, hamstrings and gastrocnemii muscles in elite adolescent soccer players during the pre-contact and early stance phases of an unanticipated side-cut and cross-cut. For the early stance phase of the two maneuvers, females demonstrated greater rectus femoris activity compared to males. Throughout the pre-contact phase of the maneuvers, a rectus femoris activation difference was identified with females having an earlier and more rapid rise in muscle activity as initial ground contact approached. Females demonstrated greater lateral and medial gastrocnemii activity for the pre-contact and early stance phases of the side-cut and greater lateral gastrocnemii activity during early stance of the cross-cut. Timing of hamstring activity also differed between genders prior to foot contact. The differences suggest that the activation patterns observed in females might not be providing adequate joint protection and stability, thereby possibly having a contributing role towards increased non-contact ACL injuries in females.

Walking in an unstable Masai Barefoot Technology (MBT) shoe introduces kinematic and kinetic changes at the hip, knee and ankle before and after a 6-week accommodation period: a comprehensive analysis using principal component analysis (PCA)

Background: Scientific and anecdotal evidence suggests that some individuals who wear the unstable Masai Barefoot Technology (MBT) shoe experience a reduction in back and joint pain. A more comprehensive biomechanical gait analysis is needed to better understand the mechanisms for symptom relief and what the long-term implications of wearing these shoes might be on the body. Objective: The aim of this study was to determine the gait changes introduced at the hip, knee and ankle before and after wearing an unstable MBT shoe for a 6-week accommodation period. Methods: Three-dimensional joint angles and moments were measured for 23 healthy individuals while walking in an unstable MBT shoe and a stable control shoe, both before and after a 6-week accommodation period of wearing the unstable shoe at their workplace. Principal component analysis (PCA) was used on the stance phase waveforms to identify differences between the two shoes and two testing sessions. Results: Joint angle and moment differences between the two shoe conditions were identified both before and after wearing the unstable shoe for the accommodation period. Notable kinematic changes included reduced hip flexion–extension and ankle adduction–abduction range of motion, increased early stance dorsiflexion and increased knee internal rotation for unstable shoe walking. Ankle moments tended to be greater for the unstable shoe and at the hip and knee, both increases and decreases in moments were observed. Conclusions: While many of the identified changes agree with previous research, this is the first study to report increases in some joint moments for the unstable MBT shoe. These increases along with other notable changes do, however, require further investigation to better understand the long-term implications of the unstable MBT shoe.

Obesity is associated with prolonged activity of the quadriceps and gastrocnemii during gait

PURPOSE To examine the effect of obesity and its potential interaction with knee OA presence on the electromyography patterns of the major knee joint periarticular muscles during walking. SCOPE One hundred and eighteen asymptomatic adults and 177 adults with moderate knee osteoarthritis were subdivided into categories of healthy weight (n = 77; 20 kg/m(2) < BMI < 25 kg/m(2)), overweight (n = 117; 25 kg/m(2) ⩽ BMI < 30 kg/m(2)), and obese (n = 101; BMI ⩾ 30 kg/m(2) based on their body mass index (BMI). All individuals underwent a three-dimensional gait analysis. Surface electromyograms from the lateral and medial gastrocnemii, lateral and medial hamstrings, vastus lateralis, vastus medialis, and rectus femoris were recorded during self-selected speed walking. Principal component analysis was used to extract major features of amplitude and temporal pattern variability from the electromyograms of each muscle group (gastrocnemii, quadriceps, hamstrings separately). Analysis of variance models tested for main BMI category effects and interaction effects for these features (α = 0.05). Statistically significant BMI category (i.e. obesity) effects were found for features that described more prolonged activations of the gastrocnemii and quadriceps muscles during the stance phase of gait with obesity (P < 0.05). CONCLUSIONS Obesity was associated with prolonged activation of quadriceps and gastrocnemii, which can result in prolonged knee joint contact loading, and thereby may contribute to the predisposition of knee OA development and progression in obese individuals.

Torsion of the foot in low cut basketball shoes in four cutting movements

The MVC results (Figure 1) illustrate the angle dependent torque development of pronators and supinators. The pronator and supinator curves reveal an ascending-descending and a descending characteristic, respectively. M. peroneus longus shows highest activity in IEMG during pronations, m. tibialis anterior is about 65–94% active with respect to m. peroneus longus. M. tibialis anterior (70%) and M. soleus (39%) are the primary muscles based on the surface EMG recordings that contribute to maximum voluntary supinations.

MALE AND FEMALE ADOLESCENT SOCCER PLAYERS DEMONSTRATE DIFFERENT NEUROMUSCULAR PATTERNS DURING THE PRE-CONTACT AND EARLY STANCE PHASE OF UNANTICIPATED RUNNING AND CUTTING MANEUVERS

S.C. Landry, K.A. McKean, C.L. Hubley-Kozey, W.D. Stanish and K.J. Deluzio School of Biomedical Engineering, Dalhousie University, Halifax, Canada, School of Physiotherapy, Dalhousie University, Halifax, Canada, Department of Surgery, Division of Orthopaedics, Dalhousie University, Halifax, Canada, Department of Mechanical and Materials Engineering, Queen’s University, Kingston, Canada; email: landrys@dal.ca

Effect of limb dominance and sex on neuromuscular activation patterns in athletes under 12 performing unanticipated side-cuts

Non-contact ACL injuries are one of the most common injuries to the knee joint among adolescent/collegiate athletes, with sex and limb dominance being identified as risk factors. In children under 12years of age (U12), these injuries occur less often and there is no sex-bias present. This study set out to explore if sex and/or limb dominance differences exist in neuromuscular activations in U12 athletes. Thirty-four U12 males and females had six bilateral muscles analyzed during unanticipated side-cuts. Principal component analysis was performed, capturing differences in overall magnitudes and timing of peak magnitudes. Two-way mixed-model ANOVAs determined significant limb effects with both sexes displaying (i) greater magnitudes in the lateral gastrocnemius and both hamstrings in the dominant limb and (ii) earlier timing of peak magnitudes in both gastrocnemii, both hamstrings and vastus medialis in the non-dominant limb, while no sex differences were identified. This study demonstrated that limb dominance, not sex, affects neuromuscular activation strategies in U12 athletes during unanticipated side-cuts. When developing injury prevention programs for younger athletes, an increased focus on balancing neuromuscular activations in both limbs could be beneficial in reducing the likelihood of ACL injuries in these athletes as they mature through puberty.

UNANTICIPATED RUNNING AND CROSS-CUTTING MANEUVERS DEMONSTRATE NEUROMUSCULAR AND LOWER LIMB BIOMECHANICAL DIFFERENCES BETWEEN ELITE ADOLESCENT MALE AND FEMALE SOCCER PLAYERS

S.C. Landry, K.A. McKean, C.L. Hubley-Kozey, W.D. Stanish and K.J. Deluzio School of Biomedical Engineering, Dalhousie University, Halifax, Canada, School of Physiotherapy, Dalhousie University, Halifax, Canada, Department of Surgery, Division of Orthopaedics, Dalhousie University, Halifax, Canada, Department of Mechanical and Materials Engineering, Queen’s University, Kingston, Canada; email: landrys@dal.ca