Single-legged landing behavior of high school basketball players with chronic ankle instability.

OBJECTIVES: Anterior cruciate ligament injury is one of the most serious ligamentous injuries. The purpose is to compare the impact of the ankle joint on the knee during landing between athletes with chronic instability and a control group (coper group) and to verify the effects of the kinetic chain from other joints. DESIGN: Prospective study. SETTING: High school basketball. PARTICIPANTS: Participants were 62 female high school basketball players who had participated in team sports for >6 months. MAIN OUTCOME MEASURES: Player joint angles, movements, and moments. RESULTS: The knee valgus moment was significantly higher in the chronic ankle instability group than in the coper group (20%-60% [p < 0.01]; 80%-100% [p < 0.05]) during landing motion. The knee valgus moment was also significantly higher during the change from the maximum knee joint flexion position to the maximum extension (p < 0.05). In addition, the landing motions of the chronic instability group may have utilized suboptimal compensatory motor strategy on the sagittal plane, depending heavily on the knee joint's abduction moment. CONCLUSIONS: Our findings indicate that the chronic ankle instability group uses a different landing strategy pattern than the coper group by changing the joint moment and joint angle during landing, which may increase the risk of anterior cruciate ligament injury.

Hamstring Tendon Autograft Is Associated With Increased Knee Valgus Moment After Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis.

BACKGROUND: There is limited evidence related to the effects of autograft type on functional performance after anterior cruciate ligament reconstruction (ACLR). PURPOSE/HYPOTHESIS: This study aimed to compare biomechanical outcomes during a drop vertical jump (DVJ) between patients with a hamstring tendon (HT) autograft, quadriceps tendon (QT) autograft with bone block, QT autograft without bone block, and bone-patellar tendon-bone autograft at 6 months postoperatively in an adolescent population. The authors' hypothesized there would be differences in DVJ biomechanics between athletes depending on the type of autograft used. STUDY DESIGN: Controlled laboratory study. METHODS: Patients aged 8 to 18 years who underwent primary ACLR were included for analysis. Kinematic and kinetic data collected during a DVJ using a 3-dimensional computerized marker system were assessed at 6 months after ACLR and compared with the uninjured contralateral limb. RESULTS: A total of 155 participants were included. There were no significant differences in terms of age, sex, or affected leg (P≥ .1973) between groups. The HT group was significantly associated with a larger knee valgus moment at initial contact compared with the QT group (28 × 10-2 vs -35 × 10-2 N·m/kg, respectively; P = .0254) and a significantly larger maximum hip adduction moment compared with the QT with bone block group (30 × 10-2 vs -4 × 10-2 N·m/kg, respectively; P = .0426). Both the QT with bone block (-12 × 10-2 vs -3 × 10-2 N·m/kg, respectively; P = .0265) and QT (-13 × 10-2 vs -3 × 10-2 N·m/kg, respectively; P = .0459) groups demonstrated significantly decreased mean knee extension moments compared with the HT group. CONCLUSION: The findings of this study suggest that utilizing an HT autograft resulted in a significantly increased knee valgus moment at initial contact compared with a QT autograft without bone block at 6 months after ACLR in adolescent patients performing a DVJ. A QT autograft was found to be associated with significantly decreased extensor mechanism function compared with an HT autograft. CLINICAL RELEVANCE: This study adds unique kinematic and kinetic information regarding various ACLR autograft options and highlights the biomechanical deficits that should be taken into consideration in rehabilitation.

Factors that Increase Elbow Stress in the Throwing Athlete: a Systematic Review of Biomechanical and Motion Analysis Studies of Baseball Pitching and Throwing.

PURPOSE OF REVIEW: Elbow pain poses a unique challenge in the throwing athlete. Due to the high levels of elbow stress during the throwing motion, elbow injuries are common in throwers of all ages. There are several postulated factors believed to contribute increased stress to the throwing elbow. A detailed review of the published biomechanical studies evaluating the stresses experienced by the throwing elbow is needed. Here, we review these biomechanical studies to extrapolate the contributing factors that increase stress, the modifications that may reduce such stress, and the post-injury rehabilitation that optimizes outcomes and reduces recurrence. RECENT FINDINGS: The biomechanical forces on the elbow have been further investigated delineated in recent work. Rotational malalignment of the shoulder, including both GIRD and decreased adduction, increases torque experienced by the elbow during pitching motions. Exact interactions between lower extremity, lumbopelvic or trunk rotation, and elbow forces during throwing remain uncertain with mixed results in recent literature. Pitch types may influence elbow stresses although delivery mechanism and distance thrown do not. Several biomechanical factors influence the stresses imparted on the throwing elbow. Throwing volume, proper throwing mechanics, and appropriate rehabilitation are likely to be to be the most influential on mitigating unnecessary stresses imparted to the elbow in the throwing athlete. A proper understanding of these factors may reduce the occurrence of these injuries in this population. Moreover, an understanding of proper rehabilitation following injury may ensure optimized results and reduce recurrence.

Effect of Foot Progression Angle and Lateral Wedge Insole on a Reduction in Knee Adduction Moment.

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle.

KINEMATIC ANALYSIS OF KNEE VALGUS DURING DROP VERTICAL JUMP AND FORWARD STEP-UP IN YOUNG BASKETBALL PLAYERS.

PURPOSE/BACKGROUND: Lower limb asymmetry between dominant and nondominant limbs is often associated with injuries. However, there is a lack of evidence about frontal plane projection angle (FPPA) of the knee joint (knee valgus) during drop vertical jump (DVJ) and forward step-up tasks (FSUP) in young basketball players. Therefore, the purpose of this study was to assess the FPPA (i.e., dynamic knee valgus) via 2D video analysis during DVJ and FSUP tasks in the dominant and nondominant limbs of young male basketball players. METHODS: Twenty seven young male basketball players (age 14.5 ± 1.3 y, height 161.1 ± 4.1 cm, weight 64.2 ± 10.2 kg) participated in this study. The participants were asked to perform a bilateral DVJ and unilateral FSUP tasks. Kinematic analysis of FPPA was completed via a two-dimensional (2D) examination in order to evaluate the knee valgus alignment during the beginning of the concentric phase of each task. Knee valgus alignment was computed considering the angle between the line formed between the markers at the anterior superior iliac spine and middle of the tibiofemoral joint and the line formed from the markers on the middle of the tibiofemoral joint to the middle of the ankle mortise. Paired t-tests were used to evaluate differences in tasks. Standard error of measurement (SEM) was calculated to establish random error scores. RESULTS: There was no difference in knee valgus angle during the DVJ task between dominant (20.2 ± 4.4 º) and nondominant legs (20 ± 4.1 º; p = 0.067). However, a significant difference was noted during FSUP between the non-dominant limb (18.7 ± 3.4 º) when compared to the dominant (21.7 ± 3.5 º; p = 0.001) limb. CONCLUSION: Two dimensional kinematic analysis of knee FPPA may help coaches and other professionals to detect asymmetries between dominant and nondominant limbs, and to develop training programs with the goal of reducing overall lower extremity injury risk. LEVEL OF EVIDENCE: 2b.

The effect of external ankle support on the kinematics and kinetics of the lower limb during a side step cutting task in netballers.

BACKGROUND: Excessive knee valgus moments are considered to be a risk factor for non-contact injuries in female athletes. Knee injuries are highly prevalent in netballers and are significant in terms of cost and disability. The aim of the study was to identify if changes in external ankle support mechanisms effect the range of motion and loading patterns at the ankle and knee joint during a sidestep cutting manoeuvre in high performance netball players. METHODS: Netballers with no previously diagnosed ankle or knee injury (n = 10) were recruited from NSW Institute of Sport netball programme. Kinematic and kinetic data were collected simultaneously using a 3-D Motion Analysis System and a force platform to measure ground reaction forces. Players performed repeated side step cutting manoeuvres whilst wearing a standard netball shoe, the same shoe with a lace-up brace and a high-top shoe. RESULTS: The brace condition significantly reduced ankle joint ROM in the sagittal plane by 8.9° ± 2.4 when compared to the standard netball shoe (p = 0.013). No other significant changes were seen between conditions for either kinematic or kinetic data. All shoe conditions did however produce knee valgus moments throughout the cutting cycle that were greater than those considered excessive in the previous literature (0.59 Nm/kg-Bwt). CONCLUSIONS: The results show that an external ankle support brace can be used to reduce the ROM at the ankle in the sagittal plane without affecting the loading of the joints of the lower limb. Internal varus moments generated at the knee during the task were however greater than values reported in the literature to classify excessive knee joint moments, regardless of the condition. All netballers exhibited lower extremity patterns and alignments previously associated with increased peak external valgus moments including; increasing hip abduction, peak hip flexion and internal rotation during early contact and high laterally directed ground reaction forces. Increased external valgus knee loads have been strongly linked to the development of non-contact injuries at the knee in female athletes and could highlight a potential mechanism for the development non-contact knee injuries in netballers performing side step cutting tasks.

The effects of core muscle activation on dynamic trunk position and knee abduction moments: implications for ACL injury.

Anterior cruciate ligament (ACL) injury is one of the most common serious lower-extremity injuries experienced by athletes participating in field and court sports and often occurs during a sudden change in direction or pivot. Both lateral trunk positioning during cutting and peak external knee abduction moments have been associated with ACL injury risk, though it is not known how core muscle activation influences these variables. In this study, the association between core muscle pre-activation and trunk position as well as the association between core muscle pre-activation and peak knee abduction moment during an unanticipated run-to-cut maneuver were investigated in 46 uninjured individuals. Average co-contraction indices and percent differences between muscle pairs were calculated prior to initial contact for internal obliques, external obliques, and L5 extensors using surface electromyography. Outside tilt of the trunk was defined as positive when the trunk was angled away from the cutting direction. No significant associations were found between pre-activations of core muscles and outside tilt of the trunk. Greater average co-contraction index of the L5 extensors was associated with greater peak knee abduction moment (p=0.0107). Increased co-contraction of the L5 extensors before foot contact could influence peak knee abduction moment by stiffening the spine, limiting sagittal plane trunk flexion (a motion pattern previously linked to ACL injury risk) and upper body kinetic energy absorption by the core during weight acceptance.

Frontal plane knee moments in golf: effect of target side foot position at address.

Golf has the potential to keep people active well into their later years. Injuries to the target side knee have been reported in golfers, yet no mechanisms for these injuries have been proposed. The loads on the knee during the golf swing may be insufficient to cause acute injury, yet they may be a factor in the progression of overuse/degenerative conditions; therefore, research developing swing modifications that may alter loading of the knee is warranted. It has been suggested that the proper golf set-up position has the target-side foot externally rotated but no reasoning for this modification has been provided. Frontal plane knee moments have been implicated in many knee pathologies. Therefore, this study used a 3-dimensional link segment model to quantify the frontal plane knee moments during the golf swing in a straight (STR) and externally rotated (EXT) target-side foot position. Subjects were 7 collegiate golfers and knee moments were compared between conditions using repeated measures T-tests. The golf swing knee moment magnitudes were also descriptively compared to those reported for two athletic maneuvers (drop jump landing, side-step cutting) and activities of daily living (gait, stair ascent). The EXT condition decreased the peak knee adduction moment as compared to the STR condition; however, foot position had no effect on the peak knee abduction moment. Also, the magnitude of the knee adduction moments during the two activities of daily living were 9-33% smaller than those experienced during the two different golfing conditions. The drop jump landing and golf swing knee moments were of similar magnitude (STR= - 5%, EXT= + 8%); however, the moments associated with side- step cutting were 50-71% larger than those on the target side knee during the golf swing. The loading of the target side knee during the golf swing may be a factor in the development and progression of knee pathologies and further research should examine ways of attenuating these loads through exercise and swing modifications. Key pointsAn externally rotated front foot position at address would be recommended for those with medial knee pathology in the target side limb.There is a large valgus moment on the target side knee during the golf swing that is not decreased with external rotation of the foot at address.The potential of the knee moments on the target side limb to lead to knee pathologies in golfers needs to be further investigated.