Ankle dislocation without fracture: an on-field perspective.
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Adolescent↗
Biomedical subjects
Erik A Wikstrom
Publications and source records attributed to Erik A Wikstrom.
Gender and limb differences in dynamic postural stability during landing.
OBJECTIVE: To determine if gender and limb dominance affect dynamic postural stability and vertical ground reaction force data during jump landings. Secondary objective was to assess the reliability of the dynamic postural stability index (DPSI). DESIGN: A mixed model (2 genderx2 limb) repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability. Subjects were required to perform a two-legged jump to a height equivalent of 50% of their maximum vertical leap, land on a single-leg and balance for three seconds. SETTING: Sports Medicine Research Laboratory. PARTICIPANTS: Forty healthy subjects (20 men, 20 women) participated in this investigation. MAIN OUTCOME MEASURES: The DPSI and its directional components quantified dynamic postural stability during a single-leg jump landing. Normalized vertical ground reaction force data quantified energy absorption. RESULTS: DPSI values revealed that females had significantly different dynamic postural stability as compared to males in the vertical plane [T (78)=-4.2, P<0.01], and in the composite score (dynamic postural stability index) [T (78)=-6.3, P<0.01]. In addition, females had significantly higher peak vertical ground reaction forces [T (78)=-13, P=0.01] than males. The DPSI also showed excellent reliability (ICC=0.96), with a 95% confidence interval ranging from 0.94 to 0.97. CONCLUSIONS: The results indicate that females have higher dynamic postural stability scores in the vertical direction as well as the composite score. This suggests that females used different dynamic postural stability strategies than males. There were no side-to-side dynamic postural stability differences between healthy contralateral limbs.
Adult↗
Measurement and evaluation of dynamic joint stability of the knee and ankle after injury.
Injuries to the lower extremity, specifically the knee and ankle joints of the human body can occur in any athletic event and are most prevalent in sports requiring cutting and jumping manoeuvres. These joints are forced to rely on the dynamic restraints to maintain joint stability, due to the lack of bony congruence and the inability of the static restraints to handle the forces generated during functional tasks. Numerous variables (proprioception, postural control, electromyography, kinetics/kinematics, dynamic stability protocols) have been measured to better understand how the body maintains joint stability during a wide range of activities from static standing to dynamic cutting or landing from a jump. While the importance of dynamic restraints is not questioned, a recent impetus to conduct more functional or sport-specific testing has emerged and placed a great deal of emphasis on dynamic joint stability and how it is affected by lower extremity injuries. Evidence suggests that surgery and aggressive rehabilitation will not necessarily restore the deficits in dynamic joint stability caused by injury to the anterior cruciate ligament or lateral ankle ligaments. In today's athletic society, there is a major push to return athletes to play as quickly as possible. However, the ramifications of those decisions have not been fully grasped. If an athlete is not fully recovered, a quick return to play could start a vicious cycle of chronic injuries or permanent disability.
Ankle Injuries↗
Detection of dynamic stability deficits in subjects with functional ankle instability.
PURPOSE: To determine which combination of landing protocol and analysis technique would be the most effective at detecting differences in dynamic stability between healthy subjects and subjects with functional ankle instability (FAI). METHODS: Fifty-eight subjects participated in this investigation: 29 healthy individuals and 29 individuals with FAI. Subjects were assessed during a single test session for time to stabilization (TTS) in the anterior/posterior, medial/lateral, and vertical directions from two protocols: a step down and jump protocol. The step down protocol started with each subject atop a 20-cm-high platform, and the jump protocol started with subjects in a standing position 70 cm from the center of a force plate and required each subject to jump off both legs and touch a designated marker placed at a position equivalent to 50% of the subject's maximum vertical leap. TTS scores in the anterior/posterior, medial/lateral, and vertical direction were compared between group, protocol, and type of analysis. RESULTS: A significant protocol by analysis by group interaction (F(1,56) = 6.9, P = 0.011) was observed for anterior/posterior TTS. Likewise, protocol by group (F(1,56) = 4.4, P = 0.042) and protocol by analysis (F(1,56) = 14.1, P < 0.001) interactions were also noted in anterior/posterior TTS. The jump protocol (2381.7 +/- 36.5 ms) produced significantly greater TTS scores in the vertical direction than the step protocol (1533.5 +/- 71.8 ms), whereas the unbounded third order polynomial (UTOP) method (2554.4 +/- 68.7 ms) produced significant greater TTS scores as compared with the sequential estimation (SE) method (1360.8 +/- 52.1 ms). CONCLUSIONS: The jump protocol and UTOP method of analysis are the most effective TTS combination in detecting differences between healthy and FAI groups.
Adult↗
Dynamic Stabilization Time After Isokinetic and Functional Fatigue.
OBJECTIVE: To compare the effects of an isokinetic fatigue protocol and a functional fatigue protocol on time to stabilization (TTS), ground reaction force (GRF), and joint kinematics during a jump landing. DESIGN AND SETTING: Subjects were assessed on 2 occasions for TTS, GRF, and joint kinematics immediately before and after completing a fatigue protocol. One week separated the 2 sessions, and the order of fatigue protocols was randomly assigned and counterbalanced. SUBJECTS: Twenty healthy male (n = 8, age = 21.8 +/- 1.4 years, height = 180.6 +/- 7.6 cm, and mass = 74.1 +/- 13.0 kg) and female (n = 12, age = 22.2 +/- 2.1 years, height = 169.3 +/- 9.8 cm, and mass = 62.5 +/- 10.1 kg) subjects volunteered to participate. MEASUREMENTS: Subjects performed 2-legged jumps equivalent to 50% of maximum jump height, followed by a single-leg landing onto the center of a forceplate 70 cm from the starting position. Peak vertical GRF and vertical, medial-lateral, and anterior-posterior TTS were obtained from forceplate recordings. Maximum ankle dorsiflexion, knee-flexion, and knee-valgum angles were determined using 3-dimensional motion analysis. RESULTS: A 2-way analysis of variance with repeated measures revealed no significant differences when comparing TTS, GRF, and joint kinematics after isokinetic and functional fatigue protocols. CONCLUSIONS: No difference was noted between isokinetic and functional fatigue protocols relative to dynamic stability when landing from a jump.
Journal Article↗
A new force-plate technology measure of dynamic postural stability: the dynamic postural stability index.
CONTEXT: New measures of dynamic postural stability are needed to address weaknesses of previous measures. OBJECTIVE: To assess the feasibility, reliability, and precision of a new measure of dynamic postural stability. DESIGN: A single within-subjects design was used to determine optimal sampling interval as well as intersession reliability. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: Eighteen subjects (7 men [age = 22 +/- 3 years, height = 175 +/- 5 cm, mass = 75 +/- 16 kg] and 11 women [age = 23 +/- 2 years, height = 163 +/- 6 cm, mass = 68 +/- 13 kg]) without lower extremity impairment. INTERVENTION(S): A jump protocol that required subjects to perform a 2-legged jump to a height equivalent to 50% of their maximum vertical leap and land on a single leg. MAIN OUTCOME MEASURE(S): The Dynamic Postural Stability Index (DPSI) and the directional components (medial-lateral, anterior-posterior, and vertical) after a jump landing. RESULTS: We observed a significant sampling-interval main effect (F(2,51) = 26.88, P < .01) for the DPSI; the 10-second trial duration produced significantly smaller means than the 5- and 3-second trial durations, whereas the 5-second trial result was also significantly smaller than that of the 3-second trial. The DPSI was highly reliable between test sessions (intraclass correlation coefficient = .96) and very precise (SEM = .03). CONCLUSIONS: These results suggest that the DPSI can be used in conjunction with a functional single-leg hop stabilization test and is a reliable and precise measure of dynamic postural stability. We believe the shortest sampling interval (3 seconds) is the best choice for studying and mimicking athletic performance as closely as possible.
Journal Article↗
Dynamic postural stability in subjects with braced, functionally unstable ankles.
CONTEXT: Research concerning prophylactic ankle stabilizers (PASs) has focused on healthy subjects, and the results cannot be generalized to the functional ankle instability (FAI) population, a population that has an increased risk of reinjury and is likely to wear PASs. OBJECTIVE: To determine whether PASs improve dynamic postural stability in FAI subjects as compared with a control (no-brace) condition. DESIGN: A crossover design was used to determine the effects of PASs on dynamic postural stability and vertical ground reaction forces. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-eight subjects with unilateral FAI, 13 men (age = 21.5 +/- 1.2 years, height = 181.5 +/- 10.5 cm, mass = 77.6 +/- 17.2 kg) and 15 women (age = 20.5 +/- 1.1 years, height = 169.4 +/- 8.2 cm, mass = 67.9 +/- 8.8 kg). INTERVENTION(S): A jump protocol required subjects to perform a 2-legged jump to a height equivalent to 50% of their maximum vertical leap and land on a single leg. MAIN OUTCOME MEASURE(S): The dynamic postural stability index, the directional components (medial-lateral, anterior-posterior, and vertical), and vertical ground reaction force after a jump landing. RESULTS: Compared with the control condition, only the vertical component score was reduced (improved) with the application of a soft or semirigid PAS (P < .01). CONCLUSIONS: Soft and semirigid PASs did not improve dynamic postural stability as measured by the Dynamic Postural Stability Index. However, PASs may help with the attenuation of vertical forces.
Journal Article↗