Mikel R. Stiffler

Jump-landing mechanics after anterior cruciate ligament reconstruction: a landing error scoring system study.

CONTEXT The Landing Error Scoring System (LESS) is a clinical evaluation of jump-landing mechanics and may provide useful information in assisting with return-to-sport decisions in patients after anterior cruciate ligament reconstruction (ACLR). However, it is currently unknown how patients with ACLR perform on the LESS compared with healthy controls. OBJECTIVE To determine if the total LESS score differed between individuals with ACLR and healthy controls and to determine the types of errors that differ between groups. DESIGN Cross-sectional study. SETTING Research laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 27 individuals with unilateral ACLR (age = 19.8 ± 1.8 years, height = 170 ± 5.5 cm, mass = 68.8 ± 11.9 kg) and 27 controls (age = 20.5 ± 1.7 years, height = 169 ± 8.4 cm, mass = 66.6 ± 9.0 kg) with no history of ACLR. INTERVENTION(S) Each participant completed 3 trials of a standardized jump-landing task. MAIN OUTCOME MEASURE(S) Each jump landing was assessed for specific postures using standardized LESS criteria by a blinded evaluator. Individual LESS items were summed to create a total LESS score. The dominant limb was assessed in the control group, and the reconstructed limb was assessed in the ACLR group. RESULTS The ACLR group had higher LESS scores compared with controls (ACLR: 6.7 ± 2.1 errors, control: 5.6 ± 1.5 errors, P = .04). Additionally, the ACLR group was more likely to err when landing with lateral trunk flexion (Fisher exact test, P = .002). CONCLUSIONS Individuals with ACLR had worse landing mechanics as measured by the LESS. Lateral trunk deviation may be related to quadriceps avoidance in the reconstructed limb or poor trunk neuromuscular control. The LESS is useful for evaluating landing errors in patients with ACLR and may help to identify areas of focus during rehabilitation and before return to sport.

High School Sport Specialization Patterns of Current Division I Athletes

Background: Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. Hypothesis: College athletes will display increased rates of specialization as they progress through their high school careers. Study Design: Descriptive epidemiological study. Level of Evidence: Level 4. Methods: Three hundred forty-three athletes (115 female) representing 9 sports from a Midwest Division I University completed a previously utilized sport specialization questionnaire regarding sport participation patterns for each grade of high school. McNemar and chi-square tests were used to investigate associations of grade, sport, and sex with prevalence of sport specialization category (low, moderate, high) (a priori P ≤ 0.05). Results: Specialization increased throughout high school, with 16.9% (n = 58) and 41.1% (n = 141) of athletes highly specialized in 9th and 12th grades, respectively. Football athletes were less likely to be highly specialized than nonfootball athletes for each year of high school (P < 0.001). There was no difference in degree of specialization between sexes at any grade level (P > 0.23). Conclusion: The majority of Division I athletes were not classified as highly specialized throughout high school, but the prevalence of high specialization increased as athletes progressed through high school. Nonfootball athletes were more likely to be highly specialized than football athletes at each grade level. Clinical Relevance: Most athletes who are recruited to participate in collegiate athletics will eventually specialize in their sport, but it does not appear that early specialization is necessary to become a Division I athlete. Athletes should be counseled regarding safe participation in sport during high school to minimize injury and maximize performance.

Star Excursion Balance Test Performance Varies by Sport in Healthy Division I Collegiate Athletes

STUDY DESIGN Cross-sectional. OBJECTIVES To describe performance and asymmetry on the Star Excursion Balance Test (SEBT) by sex and sport, and to determine if differences exist within a collegiate athlete population. BACKGROUND Performance on the SEBT may differ between sexes and levels of competition, though the results of previous studies have been inconsistent. Investigation of performance and asymmetry differences between sports is limited. Sex- and sport-specific reference values likely need to be determined to best assess SEBT performance. METHODS Performance on the SEBT was retrospectively reviewed in 393 healthy National Collegiate Athletic Association Division I collegiate athletes from 8 sports. Means, standard deviations, and 95% confidence intervals were calculated for all variables. Normalized reach distance (percent limb length) and asymmetry between limbs were compared for the anterior (ANT), posterolateral (PL), and posteromedial (PM) directions and for the composite (COMP) score using a 2-way analysis of variance (ANOVA) of sex by sport, and a 1-way ANOVA to separately compare sports within each sex. RESULTS Average normalized reach distance ranged from 62% to 69%, 84% to 97%, and 99% to 113% in the ANT, PL, and PM directions, respectively, and from 82% to 92% in the COMP score. Normalized asymmetry ranged from 3% to 4%, 5% to 8%, and 5% to 6% in the ANT, PL, and PM directions, respectively. A significant sex-by-sport interaction (P = .039) was observed in the ANT direction, with a sex effect for soccer players (P<.001; men less than women). Significant differences were observed in the PL and PM directions and in the COMP score among womens teams, with womens ice hockey players reaching the farthest (COMP, 90.0%). Among mens teams, significant differences were observed in all directions and in the COMP score. Mens ice hockey players (COMP, 91.9%) and wrestlers achieved the farthest distances (COMP, 88.8%). CONCLUSION Performance on the SEBT varies by team, with a difference between sexes also present for soccer. Performance on the SEBT and potential injury risk should be interpreted within the context of the athletes sport.

Squatting Mechanics in People With and Without Anterior Cruciate Ligament Reconstruction The Influence of Graft Type

Background: Single-legged squat mechanics change after anterior cruciate ligament (ACL) reconstruction and rehabilitation, but it is unclear if changes in squat mechanics are graft specific. Purpose: To investigate graft differences in biomechanics of the knee, hip, and trunk during the single-legged squat in patients with ACL-reconstructed knees, determine if these factors were associated with deficits in knee extension moment, and determine if subjective knee function and squat biomechanics are related. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 106 individuals were grouped based on surgical status and graft type (51 control, 34 bone–patellar tendon–bone [BPTB], 21 ipsilateral semitendinosus and gracilis autograft [ISGA]). Motion capture interfaced with force plates was used to capture single-legged squat performance in the ACL reconstructed and dominant control limbs. Variables were captured at peak knee flexion. Results: Controls exhibited greater knee extension moment (P = .04), knee flexion (P = .002), and hip adduction angles (P = .04) compared with the reconstructed groups. The ISGA group demonstrated greater forward (P = .01) and lateral (P = .002) trunk flexion over the reconstructed limb. Summated extension moment did not differ between groups (P = .42). Knee extension moment was correlated with lateral trunk flexion (r = −0.31, P = .03) in the control group and knee flexion angle (r = −0.44, P = .04) in the ISGA group. Subjective knee function scores were correlated with lateral trunk flexion (r = −0.45, P = .008) in the BPTB group and with hip adduction angle (r = −0.46, P = .04) and hip extension moment (r = 0.48, P = .03) in the ISGA group. Conclusion: Knee and hip biomechanics were related to surgical status but not graft type. Increased forward and lateral trunk motion in the ISGA group may be a mechanism to protect the knee by minimizing motion during squatting or related to surgical selection bias. Secondary findings (summated extensor moments and correlations) most likely represent a strategy to shift the squat demands from the knee to the hip. Clinical Relevance: Clinicians should target these neuromuscular deficits during rehabilitation and training programs after ACL reconstruction.

Range of motion, postural alignment, and LESS score differences of those with and without excessive medial knee displacement.

Objective:To determine range of motion (ROM), postural alignment, and dynamic motion differences between those with and without medial knee displacement (MKD) during the overhead squat (OHS). We hypothesized those with MKD would have restricted ROM, differing postural alignment, and poorer quality dynamic motion than those without MKD. Design:Observational. Setting:University Research Laboratory. Participants:Ninety-seven healthy recreationally active college-aged individuals. Independent Variables:Groups were determined by the presence (MKD group) or absence (control group) of MKD during an OHS. Main Outcome Measures:Range of motion measures were active and passive ankle dorsiflexion with the knee straight and bent, hip internal and external rotation, and hip abduction. Postural alignment measures were Q angle, navicular drop, and genu recurvatum. Quality of dynamic motion was measured using total Landing Error Scoring System (LESS) score. Results:The MKD group had significantly less active (P = 0.017) and passive (P = 0.045) ankle dorsiflexion with the knee straight, as well as significantly increased Q angle (P = 0.004) and decreased navicular drop (P = 0.009). There were no significant differences in total LESS score or the other outcome measures. Conclusions:There is select ROM, such as ankle dorsiflexion, and postural measures clinicians can screen for that may be related to increased MKD and theoretically elevated risk of injury.

Star Excursion Balance Test Anterior Asymmetry Is Associated With Injury Status in Division I Collegiate Athletes

STUDY DESIGN: Retrospective cohort. BACKGROUND: Star Excursion Balance Test (SEBT) performance differs by sport in healthy collegiate athletes, and lower extremity injury rates also vary by sport, sex, and athletic exposure. The relationship between SEBT performance and injury risk has not been evaluated with consideration of these additional variables, which may be necessary to fully describe the relationship between SEBT performance and injury risk. OBJECTIVES: To assess the association between preseason SEBT performance and noncontact injury occurrence to the knee or ankle in Division I collegiate athletes when controlling for sport, sex, and athletic exposure. METHODS: Star Excursion Balance Test performance, starting status, and injury status were reviewed retrospectively in National Collegiate Athletic Association Division I collegiate athletes from a single institution. A total of 147 athletes were healthy at the time of preseason SEBT testing and either remained healthy (n = 118) or sustained a noncontact injury to the knee or ankle (n = 29) during their sports subsequent competitive season. Side‐to‐side asymmetries were calculated in each direction as the absolute difference in reach distance between limbs. Star Excursion Balance Test reach distances and asymmetries were compared between groups using multivariable regression, controlling for sport, sex, and athletic exposure (starter, nonstarter). Receiver operating characteristic curves were used to determine optimal sensitivity and specificity for significant models. RESULTS: When controlling for sport, sex, and athletic exposure, SEBT side‐to‐side asymmetry in the anterior direction, expressed as an absolute or normalized to limb length, discriminated between injured and noninjured athletes (area under the curve greater than 0.82). CONCLUSION: Assessing side‐to‐side reach asymmetry in the anterior direction of the SEBT may assist in identifying collegiate athletes who are at risk for sustaining noncontact injuries to the knee or ankle. LEVEL OF EVIDENCE: Prognosis, level 2b.

Reduced Rate of Quadriceps Activation during Running and Jumping in Collegiate Athletes post-ACL Reconstruction: 1763 June 1 2

Running, jumping, and most sports activities involve sequences of rapid muscle activation and relaxation, or rapid increases and decreases in force production. Rapid quadriceps activation and force development (typically assessed with isolated, isometric methods) are reduced after anterior cruciate ligament reconstruction (ACLR). Rate of neuromuscular activation during sports activities after ACLR has not been examined. Purpose: To investigate side-to-side asymmetries in rate of neuromuscular activation of the thigh and hip muscles during jumping and running in collegiate athletes post-ACLR.

Kinetic Asymmetries During A Vertical Jump Persist During Initial Year Post Acl Reconstruction: 1106 Board #4 June 1, 3: 15 PM - 5: 15 PM.

Methods: Sixteen collegiate athletes within one year post-ACLR performed a CMJ while kinematics and ground forces were recorded. Sagittal plane work done at the hips and knees and work derived from jump power were calculated for each limb during the up and landing phases of the CMJ. Variables were compared between limbs (injured, INJ; non-injured, NON) and groups (4-8 months vs 8-12 months post-ACLR, n=8 for both) by 2-way ANOVAs.

Association Between Peak Vertical Ground Reaction Forces During Running and Jumping in Collegiate Distance Runners: 3826 Board #265 June 4, 8: 00 AM - 9: 30 AM.

Methods: Data from 39 healthy NCAA Division I cross country runners (men, 20; age: 20.1 ± 1.1yr; height: 1.7 ± 0.1m; weight: 62.5 ± 8.6kg) were reviewed. Ground reaction forces were recorded during three counter-movement jumps and treadmill running at 3.80m/s; pVGRFs were averaged across jumps and gait cycles, respectively. Directional, between-limb percent asymmetry in pVGRFs during the jump takeoff phase and stance phase of the gait cycle were calculated. Between-limb asymmetry was assessed using a paired t-test. Associations between pVGRF during jumping and running were assessed using Pearson’s r correlations.

Base Of Gait In Collegiate Distance Runners: Effects Of Speed And Gender: 3851 Board #290 June 4, 8: 00 AM - 9: 30 AM.

Base of gait (BOG), or the mediolateral distance between the foot and body’s line of gravity, during running is reduced relative to walking. Considered a strategy to reduce hip muscle loads, it has been suggested that reductions in BOG resulting in the foot crossing the line of gravity (crossover) may increase risk for iliotibial band syndrome and tibial stress injuries. However, little is known about factors that may influence BOG during running.