Anthony I. Beutler

Gender Differences in the Incidence and Prevalence of Patellofemoral Pain Syndrome

The purpose of this investigation was to determine the association between gender and the prevalence and incidence of patellofemoral pain syndrome (PFPS). One thousand five hundred and twenty‐five participants from the United States Naval Academy (USNA) were followed for up to 2.5 years for the development of PFPS. Physicians and certified athletic trainers documented the cases of PFPS. PFPS was defined as retropatellar pain during at least two of the following activities: ascending/descending stairs, hopping/jogging, prolonged sitting, kneeling, and squatting, negative findings on examination of knee ligament, menisci, bursa, and synovial plica, and pain on palpation of either the patellar facets or femoral condyles. Poisson and logistic regressions were performed to determine the association between gender and the incidence and prevalence of PFPS, respectively. The incidence rate for PFPS was 22/1000 person‐years. Females were 2.23 times (95% CI: 1.19, 4.20) more likely to develop PFPS compared with males. While not statistically significant, the prevalence of PFPS at study enrollment tended to be higher in females (15%) than in males (12%) (P=0.09). Females at the USNA are significantly more likely to develop PFPS than males. Additionally, at the time of admission to the academy, the prevalence of PFPS was not significantly different between genders.

The Landing Error Scoring System (LESS) Is a Valid and Reliable Clinical Assessment Tool of Jump-Landing Biomechanics The JUMP-ACL Study

Background Anterior cruciate ligament injuries are common in athletes and have serious sequelae. A valid clinical tool that reliably identifies individuals at an increased risk for ACL injury would be highly useful for screening sports teams, because individuals identified as “high-risk” could then be provided with intensive prevention programs. Hypothesis A clinical screening tool (the Landing Error Scoring System, or LESS) will reliably identify subjects with potentially high-risk biomechanics. Study Design Cohort study (Diagnosis); Level of evidence, 2. Methods A jump-landing-rebound task was used. Off-the-shelf camcorders recorded frontal and sagittal plane views of the subject performing the task. The LESS was scored from replay of this video. Three-dimensional lower extremity kinematics and kinetics were also collected and used as the gold standard against which the validity of the LESS was assessed. Three trials of the jump-landing task were collected for 2691 subjects. Kinematic and kinetic measures were compared across LESS score quartiles using 1-way analysis of variance; LESS quartiles were compared across genders using the chi-square test. The LESS scores from a subset of 50 subjects were rescored to determine intrarater and interrater reliability. Results Subjects with high LESS scores (poor jump-landing technique) displayed significantly different lower extremity kinematics and kinetics compared with subjects with low LESS scores (excellent jump-landing technique). Women had higher (worse) LESS scores than men. Intrarater and interrater reliability of the LESS ranged from good to excellent. Conclusion The LESS is a valid and reliable tool for identifying potentially high-risk movement patterns during a jump-landing task.

A Prospective Investigation of Biomechanical Risk Factors for Patellofemoral Pain Syndrome The Joint Undertaking to Monitor and Prevent ACL Injury (JUMP-ACL) Cohort

Background Patellofemoral pain syndrome is one of the most common chronic knee injuries; however, little research has been done to determine the risk factors for this injury. Hypothesis Altered lower extremity kinematics and kinetics, decreased strength, and altered postural measurements will be risk factors. Study Design Cohort study (prognosis); Level of evidence, 2. Methods A total of 1597 participants were enrolled in this investigation and prospectively followed from the date of their enrollment (July 2005, July 2006, or July 2007) through January 2008, a maximum of 2.5 years of follow-up. Each participant underwent baseline data collection during their pre-freshman summer at the United States Naval Academy. Baseline data collection included 3-dimensional motion analysis during a jump-landing task, 6 lower extremity isometric strength tests, and postural alignment measurements (navicular drop and Q angle). Results Risk factors for the development of patellofemoral pain syndrome included decreased knee flexion angle, decreased vertical ground-reaction force, and increased hip internal rotation angle during the jump-landing task. Additionally, decreased quadriceps and hamstring strength, increased hip external rotator strength, and increased navicular drop were risk factors for the development of patellofemoral pain syndrome. Conclusion Multiple modifiable risk factors for patellofemoral pain syndrome pain have been identified in this investigation. To decrease the incidence of this chronic injury, the risk factors for patellofemoral pain syndrome need to be targeted in injury prevention programs. Clinical Relevance Prevention programs should focus on increasing strength of the lower extremity musculature along with instructing proper mechanics during dynamic movements to decrease the incidence of patellofemoral pain syndrome.

Comparing the Incidence of Anterior Cruciate Ligament Injury in Collegiate Lacrosse, Soccer, and Basketball Players Implications for Anterior Cruciate Ligament Mechanism and Prevention

Background Female college basketball and soccer athletes have higher rates of anterior cruciate ligament injury than do their male counterparts. Rates of anterior cruciate ligament injuries for women and men in collegiate lacrosse have not been examined. Understanding anterior cruciate ligament injury patterns in lacrosse, a full-contact sport for men and noncontact sport for women, could further injury prevention efforts. Hypotheses Female anterior cruciate ligament injury rates will decrease over time owing to longer participation in sports. Lacrosse anterior cruciate ligament injury rates will be lower than rates in basketball and soccer possibly owing to beneficial biomechanics of carrying a lacrosse stick. Study Design Cohort study (Prevalence); Level of evidence, 2. Methods Data from the National Collegiate Athletic Association Injury Surveillance System were analyzed to compare mens and womens anterior cruciate ligament injuries in basketball, lacrosse, and soccer over 15 years. Results Anterior cruciate ligament injury rates in womens basketball and soccer were 0.28 and 0.32 injuries per 1000 athlete exposures, respectively, and did not decline over the study period. In mens basketball, injury rate fluctuated between 0.03 and 0.13 athlete exposures. Rates of anterior cruciate ligament injury did not significantly change in mens soccer over the study period. The rate of anterior cruciate ligament injury in mens lacrosse (0.17 athlete exposures, P < .05) was significantly higher than in mens basketball (0.08 athlete exposures) and soccer (0.12 athlete exposures). Injury rate in womens lacrosse (0.18 athlete exposures, P < .05) was significantly lower than in womens basketball and soccer. Conclusion There was no discernable change in rate of anterior cruciate ligament injury in men or women during the study period. Mens lacrosse is a high-risk sport for anterior cruciate ligament injury. Unlike basketball and soccer, the rates of anterior cruciate ligament injury are essentially the same in mens and womens lacrosse. The level of allowed contact in pivoting sports may be a factor in determining sport-specific anterior cruciate ligament risk.

Retention of Movement Pattern Changes After a Lower Extremity Injury Prevention Program Is Affected by Program Duration

Background: Changes in movement patterns have been repeatedly observed immediately after completing a lower extremity injury prevention program. However, it is not known if movement pattern changes are maintained after discontinuing the training program. Hypothesis: The ability to maintain movement pattern changes after training has ceased may be influenced by the program’s duration. The authors hypothesized that among individuals who completed either a 3-month or 9-month training program and who demonstrated immediate movement pattern changes, only those who completed the 9-month training program would maintain movement pattern changes after a 3-month period of no longer performing the exercises. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 140 youth soccer athletes from 15 separate teams volunteered to participate. Athletes’ movement patterns were assessed using the Landing Error Scoring System (LESS) at pretest, posttest, and 3 months after ceasing the program (retention test). Eighty-four of the original 140 participants demonstrated improvements in their LESS scores between pretest and posttest (change in LESS score >0) and were included in the final analyses for this study (n = 84; 20 boys and 64 girls; mean age, 14 ± 2 years; age range, 11-17 years). Teams performed 3-month (short-duration group) and 9-month (extended-duration group) injury prevention programs. The exercises performed were identical for both groups. Teams performed the programs as part of their normal warm-up routine. Results: Although both groups improved their total LESS scores from pretest to posttest, only the extended-duration training group retained their improvements 3 months after ceasing the injury prevention program (F2,137 = 3.38; P = .04). Conclusion: Results suggest that training duration may be an important factor to consider when designing injury prevention programs that facilitate long-term changes in movement control.

Seven Steps for Developing and Implementing a Preventive Training Program: Lessons Learned from JUMP-ACL and Beyond

Musculoskeletal injuries during military and sport-related training are common, costly and potentially debilitating. Thus, there is a great need to develop and implement evidence-based injury prevention strategies to reduce the burden of musculoskeletal injury. The lack of attention to implementation issues is a major factor limiting the ability to successfully reduce musculoskeletal injury rates using evidence-based injury prevention programs. We propose 7 steps that can be used to facilitate successful design and implementation of evidence-based injury prevention programs within the logical constraints of a real-world setting by identifying implementation barriers and associated solutions. Incorporating these 7 steps along with other models for behavioral health interventions may improve the overall efficacy of military and sport-related injury prevention programs.

Anterior cruciate ligament injury alters preinjury lower extremity biomechanics in the injured and uninjured leg: the JUMP-ACL study

Background Information as to how anterior cruciate ligament (ACL) injury and reconstructive surgery (ACLR) alter lower extremity biomechanics may improve rehabilitation and return to play guidelines, reducing the risk for repeat ACL injury. Aim To compare lower extremity biomechanics before ACL injury and after subsequent ACLR for the injured and uninjured leg. Methods Baseline unilateral lower extremity biomechanics were collected on the dominant leg of participants without ACL injury when they entered the Joint Undertaking to Monitor and Prevent ACL (JUMP-ACL) study. Thirty-one participants with subsequent ACL injury, reconstructive surgery and full return to physical activity completed repeat, follow-up biomechanical testing, as did 39 uninjured, matched controls. Not all injured participants suffered injury to the dominant leg, requiring separation of those with ACL injury into two groups: ACLR-injured leg group (n=12) and ACLR-uninjured leg group (n=19). We compared the landing biomechanics of these three groups (ACLR-injured leg, ACLR-uninjured leg, control) before ACL injury (baseline) with biomechanics after ACL injury, surgery and return to physical activity (follow-up). Results ACL injury and ACLR altered lower extremity biomechanics, as both ACLR groups demonstrated increases in frontal plane movement (increased hip adduction and knee valgus). The ACLR-injured leg group also exhibited decreased sagittal plane loading (decreased anterior tibial shear force, knee extension moment and hip flexion moment). No high-risk biomechanical changes were observed in control group participants. Conclusions ACL injury and ACLR caused movement pattern alterations of the injured and uninjured leg that have previously shown to increase the risk for future non-contact ACL injury.

Consortium for Health and Military Performance and American College of Sports Medicine Summit: Utility of Functional Movement Assessment in Identifying Musculoskeletal Injury Risk

Prevention of musculoskeletal injuries (MSKI) is critical in both civilian and military populations to enhance physical performance, optimize health, and minimize health care expenses. Developing a more unified approach through addressing identified movement impairments could result in improved dynamic balance, trunk stability, and functional movement quality while potentially minimizing the risk of incurring such injuries. Although the evidence supporting the utility of injury prediction and return-to-activity readiness screening tools is encouraging, considerable additional research is needed regarding improving sensitivity, specificity, and outcomes, and especially the implementation challenges and barriers in a military setting. If selected current functional movement assessments can be administered in an efficient and cost-effective manner, utilization of the existing tools may be a beneficial first step in decreasing the burden of MSKI, with a subsequent focus on secondary and tertiary prevention via further assessments on those with prior injury history.

The Effects of an Injury Prevention Program on Landing Biomechanics Over Time

Background: Knowledge is limited regarding how long improvements in biomechanics remain after completion of a lower extremity injury prevention program. Purpose: To evaluate the effects of an injury prevention program on movement technique and peak vertical ground-reaction forces (VGRF) over time compared with a standard warm-up (SWU) program. Study Design: Controlled laboratory study. Methods: A total of 1104 incoming freshmen (age range, 17-22 years) at a military academy in the United States volunteered to participate. Participants were cluster-randomized by military company to either the Dynamic Integrated Movement Enhancement (DIME) injury prevention program or SWU. A random subsample of participants completed a standardized jump-landing task at each time point: immediately before the intervention (PRE), immediately after (POST), and 2 (POST2M), 4 (POST4M), 6 (POST6M), and 8 months (POST8M) after the intervention. VGRF data collected during the jump-landing task were normalized to body weight (%BW). The Landing Error Scoring System (LESS) was used to evaluate movement technique during the jump landing. The change scores (Δ) for each variable (LESS, VGRF) between the group’s average value at PRE and each time point were calculated. Separate univariate analyses of variance were performed to evaluate group differences. Results: The results showed a greater decrease in mean (±SD) VGRF in the DIME group compared with the SWU group at all retention time points: POST2M (SWU [Δ%BW], −0.13 ± 0.82; DIME, −0.62 ± 0.91; P = .001), POST4M (SWU, −0.15 ± 0.98; DIME,−0.46 ± 0.64; P = .04), POST6M (SWU, −0.04 ± 0.96; DIME, −0.53 ± 0.83; P = .004), and POST8M (SWU, 0.38 ± 0.95; DIME, −0.11 ± 0.98; P = .003), but there was not a significant improvement in the DIME group between PRE and POST8M (Δ%BW, −0.11 ± 0.98). No group differences in Δ LESS were observed. Conclusion: The study findings demonstrated that an injury prevention program performed as a warm-up can reduce vertical ground-reaction forces compared with a standard warm-up but a maintenance program is likely necessary in order for continued benefit. Clinical Relevance: Injury prevention programs may need to be performed constantly, or at least every sport season, in order for participants to maintain the protective effects against injury.

Jump-Landing Differences Between Varsity, Club, and Intramural Athletes: The Jump-ACL Study

Abstract Theiss, JL, Gerber, JP, Cameron, KL, Beutler, AI, Marshall, SW, Distefano, LJ, Padua, DA, de la Motte, SJ, Miller, JM, and Yunker, CA. Jump-landing differences between varsity, club, and intramural athletes: The jump-ACL study. J Strength Cond Res 28(4): 1164–1171, 2014—Abnormal movement patterns have been identified as important prospective risk factors for lower extremity injury, including anterior cruciate ligament injury. Specifically, poor neuromuscular control during the early landing phase has been associated with increased injury risk. Although it is commonly assumed that higher division collegiate athletes generally exhibit better movement patterns than lower division athletes, few studies compare the biomechanical differences on basic tasks such as jump landing between various levels of athletic groups. The objective of this study was to evaluate jump-landing and fitness differences among college-aged Intramural, Competitive Club, and National Collegiate Athletic Association (NCAA) Division I level athletes. Two hundred seventy-seven student-athletes (222 men, 55 women; age 19.3 ± 0.8 years) categorized as NCAA Division I, Competitive Club, or Intramural level athletes were evaluated during a jump-landing task using the Landing Error Scoring System (LESS), a validated qualitative movement assessment. Fitness was measured using the Army Physical Fitness Test (APFT). Results showed no significant differences in landing errors between the levels of athletic group (F2,267 = 0.36, p = 0.70). There was a significant difference in landing errors between genders (F1,268 = 3.99, p = 0.05). Significant differences in APFT scores were observed between level of athletic group (F2,267 = 11.14, p < 0.001) and gender (F1,268 = 9.27, p = 0.003). There was no significant correlation between the APFT and LESS scores (p = 0.26). In conclusion, higher level athletes had better physical fitness as measured by the APFT but did not as a group exhibit better landing technique. The implications of this research suggest that “high-risk” movement patterns are prevalent in all levels of athletes.