Luciana De Michelis Mendonça

Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition—narrative review and new concept

Injury prediction is one of the most challenging issues in sports and a key component for injury prevention. Sports injuries aetiology investigations have assumed a reductionist view in which a phenomenon has been simplified into units and analysed as the sum of its basic parts and causality has been seen in a linear and unidirectional way. This reductionist approach relies on correlation and regression analyses and, despite the vast effort to predict sports injuries, it has been limited in its ability to successfully identify predictive factors. The majority of human health conditions are complex. In this sense, the multifactorial complex nature of sports injuries arises not from the linear interaction between isolated and predictive factors, but from the complex interaction among a web of determinants. Thus, the aim of this conceptual paper was to propose a complex system model for sports injuries and to demonstrate how the implementation of complex system thinking may allow us to better address the complex nature of the sports injuries aetiology. According to this model, we should identify features that are hallmarks of complex systems, such as the pattern of relationships (interactions) among determinants, the regularities (profiles) that simultaneously characterise and constrain the phenomenon and the emerging pattern that arises from the complex web of determinants. In sports practice, this emerging pattern may be related to injury occurrence or adaptation. This novel view of preventive intervention relies on the identification of regularities or risk profile, moving from risk factors to risk pattern recognition.

Foot and Hip Contributions to High Frontal Plane Knee Projection Angle in Athletes: A Classification and Regression Tree Approach

STUDY DESIGN Cross-sectional. OBJECTIVE To investigate predictors of increased frontal plane knee projection angle (FPKPA) in athletes. BACKGROUND The underlying mechanisms that lead to increased FPKPA are likely multifactorial and depend on how the musculoskeletal system adapts to the possible interactions between its distal and proximal segments. Bivariate and linear analyses traditionally employed to analyze the occurrence of increased FPKPA are not sufficiently robust to capture complex relationships among predictors. The investigation of nonlinear interactions among biomechanical factors is necessary to further our understanding of the interdependence of lower-limb segments and resultant dynamic knee alignment. METHODS The FPKPA was assessed in 101 athletes during a single-leg squat and in 72 athletes at the moment of landing from a jump. The investigated predictors were sex, hip abductor isometric torque, passive range of motion (ROM) of hip internal rotation (IR), and shank-forefoot alignment. Classification and regression trees were used to investigate nonlinear interactions among predictors and their influence on the occurrence of increased FPKPA. RESULTS During single-leg squatting, the occurrence of high FPKPA was predicted by the interaction between hip abductor isometric torque and passive hip IR ROM. At the moment of landing, the shank-forefoot alignment, abductor isometric torque, and passive hip IR ROM were predictors of high FPKPA. In addition, the classification and regression trees established cutoff points that could be used in clinical practice to identify athletes who are at potential risk for excessive FPKPA. CONCLUSION The models captured nonlinear interactions between hip abductor isometric torque, passive hip IR ROM, and shank-forefoot alignment.

Avaliação muscular isocinética da articulação do ombro em atletas da Seleção Brasileira de voleibol sub-19 e sub-21 masculino

INTRODUCTION AND PURPOSE: The shoulder complex muscles play an important role in force, power and endurance production in volleyball, allowing the accomplishment of movement in a coordinated manner. The objective written account produced by isokinetic evaluations assists in the diagnosis and prevention of shoulder complex injuries. In addition, it is a useful tool in promoting safe and fast return of the injured athlete to sports practice. The purpose of this study was to analyze the isokinetic muscle performance of the lateral and medial rotators of the glenohumeral joint in Brazilian male volleyball teams (under-19 and under-21). METHODS: The protocol used during the test included five maximum repetitions of shoulder lateral and medial rotation in concentric-concentric mode at 60o/s and 30 repetitions at 360o/s. Analysis of variance was used to evaluate the dependent variables: maximum work and maximum torque of shoulder lateral and medial rotators normalized by body mass, antagonist/agonist ratio at the two speeds and muscular fatigue index. RESULTS: Data analysis demonstrated an imbalance between the shoulder lateral and medial rotators (antagonist/agonist ratio) in the under-21 category of the Brazilian volleyball athletes, demonstrating relative weakness of the lateral rotators. CONCLUSION: It was possible to identify changes in volleyball players, which added to specific demands of the sport, can lead to symptoms in the shoulder complex and / or decrease of performance.

Factors associated with the presence of patellar tendon abnormalities in male athletes

OBJECTIVES To investigate the association between lower limb alignment, range of motion/flexibility and muscle strength with the presence of patellar tendon abnormalities in male athletes. DESIGN This was a cross-sectional study. METHODS Thirty-one male basketball and volleyball athletes were assessed for ankle dorsiflexion range of motion, shank-forefoot alignment, iliotibial band flexibility, hip external rotators and abductors isometric torque, passive hip internal rotation range of motion and frontal plane knee and patellar alignment (McConnell and Arno angles). Ultrasonographic evaluations of hypoechoic areas of the patellar tendons were performed in longitudinal and transverse planes. A receiver operating characteristic curve was used to determine clinically relevant cut-off point for each variable. When the area under the curve was statistically significant, Prevalence Ratio (PR) and 95% confidence intervals were calculated to indicate the strength of the association between the independent variable and the presence of patellar tendon abnormalities. RESULTS Receiver operating characteristic curve showed that iliotibial band flexibility (p=0.006), shank-forefoot alignment (p=0.013) and Arno angle (p=0.046) were associated with patellar tendon abnormalities. Cut-off points were established and only the Prevalence Ratio of iliotibial band flexibility (cut-off point=-0.02°/kg; PR=5.26) and shank-forefoot alignment (cut-off point=24°; PR=4.42) were statistically significant. CONCLUSIONS Athletes with iliotibial band or shank-forefoot alignment above the clinically relevant cut-off point had more chance to have patellar tendon abnormalities compared to athletes under the cut-off point values. These results suggest that such factors could contribute to patellar tendon overload, since patellar tendon abnormalities indicate some level of tissue damage. Both factors might be considered in future prospective studies.

A Quick and Reliable Procedure for Assessing Foot Alignment in Athletes

BACKGROUND Quick procedures with proper psychometric properties that can capture the combined alignment of the foot-ankle complex in a position that may be more representative of the status of the lower limb during ground contact are essential for assessing a large group of athletes. METHODS The assessed lower limb was positioned with the calcaneus surface facing upward in a way that all of the marks could be seen at the center of the camera display. After guaranteeing maintenance of the foot at 90° of dorsiflexion actively sustained by the athlete, the examiner took the picture of the foot-ankle alignment. RESULTS Intraclass correlation coefficients ranging from 0.82 to 0.93 demonstrated excellent intratester and intertester reliability for the proposed measurements of forefoot, rearfoot, and shank-forefoot alignments. The intraclass correlation coefficient between the shank-forefoot measures and the sum of the rearfoot and forefoot measures was 0.98, suggesting that the shank-forefoot alignment measures can represent the combined rearfoot and forefoot alignments. CONCLUSIONS This study describes a reliable and practical measurement procedure for rearfoot, forefoot, and shank-forefoot alignments that can be applied to clinical and research situations as a screening procedure for risk factors for lower-limb injuries in athletes.

The Accuracy of the VISA-P Questionnaire, Single-Leg Decline Squat, and Tendon Pain History to Identify Patellar Tendon Abnormalities in Adult Athletes

Study Design Cross-sectional clinical assessment. Background Patellar tendinopathy is not always accompanied by patellar tendon abnormalities (PTAs). Thus, clinical screening tools to help identify patients with patellar tendon pain who have PTAs could enhance clinical decision making and patient prognosis. Objectives To test the diagnostic accuracy of the Victorian Institute of Sport Assessment-Patella (VISA-P) questionnaire, a single-leg decline squat (SLDS), tendon pain history, age, and years of sports participation to identify athletes with symptomatic patellar tendons who have PTAs confirmed on imaging. Methods Data provided by ultrasound examination, the VISA-P questionnaire, the SLDS, tendon pain history, age, and years of sport participation were collected in 43 athletes. A classification and regression tree (CART) model was developed to verify variables associated with PTA occurrence. Likelihood ratios (LRs) were computed for positive and negative tests. Results The SLDS, VISA-P questionnaire, and tendon pain history were associated with PTA occurrence. Athletes with negative results on all 3 tests (CART model) had a lower likelihood of having PTAs (negative LR = 0.3; 95% confidence interval [CI]: 0.2, 0.5). The isolated use of the SLDS or tendon pain history (positive LR = 4.2; 95% CI: 2.3, 7.14 and 4.5; 95% CI: 1.8, 11.1, respectively) had similar influence on probability of PTA presence compared to the CART model (positive LR = 4.1; 95% CI: 2.5, 6.3). Conclusion Although the objective was to investigate a clinical test to identify PTAs, the combined use of the tests had greater accuracy to identify individuals without PTAs. Level of Evidence Diagnosis, level 3b. J Orthop Sports Phys Ther 2016;46(8):673-680. Epub 3 Jul 2016. doi:10.2519/jospt.2016.6192.

Normative values of dynamic knee valgus during single leg squat in basketball and volleyball athletes

Background Volleyball and basketball are among the sports with a higher incidence of knee injuries. The inability to maintain a proper alignment of the lower limbs during functional activities could create a knee valgus which predisposes to injury. Thus, the quantification of knee valgus is necessary to guide prevention and clinical interventions. Objective To establish normative values for dynamic knee valgus during the single leg squat (SLS) in volleyball and basketball athletes. Design Observational cross-sectional. Setting Minas Tênis Club, Brazil, youth sports. Participants 151 athletes (108 male and 43 female) were assessed during national championship preseason. All participants were healthy, with no current pain of lower limb injury and no history of previous lower extremity surgery. The mean age, weight and height were 14.21+2.09; 62.75+14.20 and 173.89+13.42, respectively. Assessment of risk factors Gender, age and sport. Main outcome measurements Knee valgus was measured as frontal plane projection angle of the knee (FPPAK) during SLS up to 60° of knee flexion. The mean of three repetitions of SLS from each limb was used for analysis, using SIMI Motion Twinner software. The FPPAK was defined as the connections between ASIS, midpoint of femoral epicondyles and anterior midpoint of the malleolis. Results The mean FPPAK during SLS for right leg was 7.08+4.0 and 8.68+4.2 for left leg. There were no differences between ages and genders. There were significant differences between sides in both modalities (p<0.000).The basketball athletes had lower FPPAK on the left leg when compared with athletes from volleyball (p<0.000). Conclusion All athletes showed an inability to maintain proper alignment during dynamic squat. The differences found between modalities may be linked to the specific technique of each sport and are important to guide an intervention focused on injury prevention.

Association of Hip and Foot Factors With Patellar Tendinopathy (Jumper's Knee) in Athletes

• BACKGROUND: Investigations on the causes of patellar tendinopathy should consider impairments at the hip and foot/ankle because they are known to influence movement patterns and affect patellar tendon loading. • OBJECTIVES: To investigate hip and foot/ankle impairments associated with patellar tendinopathy in volleyball and basketball athletes using classification and regression tree analysis. • METHODS: In this clinical measurement, cross‐sectional study, 192 athletes were assessed for impairments of the hip and foot/ankle, including shank‐forefoot alignment, dorsiflexion range of motion (ROM), iliotibial band flexibility, passive hip internal rotation ROM, and hip external rotator and hip abductor isometric strength. Athletes with tenderness and/or pain at the inferior pole of the patella were considered to have patellar tendinopathy. Athletes with scores higher than 95 points on the Victorian Institute of Sport Assessment‐patella (VISA‐P), no pain during the single‐leg decline squat, and no history of patellar tendon pain were considered not to have patellar tendinopathy. Classification and regression tree analyses were performed to identify interacting factors associated with patellar tendinopathy. • RESULTS: Interactions among passive hip internal rotation ROM, shank‐forefoot alignment, and hip external rotator and abductor strength identified athletes with and without patellar tendinopathy. The model achieved 71.2% sensitivity and 74.4% specificity. The area under the receiver operating characteristic curve was 0.77 (95% confidence interval: 0.70, 0.84; P<.001). • CONCLUSION: Impairments of the hip and foot/ankle are associated with the presence of patellar tendinopathy in volleyball and basketball athletes. Future studies should evaluate the role of these impairments in the etiology of patellar tendinopathy. • KEY WORDS: decision trees, epidemiology, knee, sports, tendon injury

Y- BALANCE TEST SCORE COMPARISON BETWEEN PRE-SEASON AND IN-SEASON IN YOUTH ATHLETES

Background The Y-balance test has been used clinically to assess neuromuscular control deficits and a composite score of <94% and anterior asymmetry of >4 cm have been associated with lower limb injuries in basketball athletes. Objective To compare Y-test performance during the pre-season to in-season in injury-free athletes. Design Prospective study. Setting Brazilian sports club, mixed sports. Patients (or Participants) 182 injury-free youth athletes (145 male and 37 female) from judo, volleyball, basketball, gymnastics and indoor soccer were assessed (age 14.3±2.8; height 168±19 cm, body mass 60±18 kg). Assessment of Risk Factors The Y-test was assessed during the pre-season (February) and in-season (June). Athletes practiced 6 trials on each leg prior to formal testing. While maintaining single-leg stance, they were asked to reach with the free limb in the anterior, posteromedial, and posterolateral directions. Main Outcome Measurements Y-test performance was calculated as the composite score (sum of the three reach distances, divided by 3 times limb length, then multiplied by 100). Anterior distance asymmetry was calculated as the difference between the dominant limb (DL) and non-dominant limb (NDL) values. Both measures were compared between pre- and in-season. Results The pre-season average composite score for DL was 87.5% and for NDL 87.8%, while the average anterior distance asymmetry was 3.7 cm. During in-season, the average composite score was 85.4% for DL and NDL, and the anterior distance asymmetry was 3.0 cm. T-tests revealed statistically significant differences for the composite score (p<0.001) and for anterior distance asymmetry (p=0.01). Conclusions Athletes showed poorer composite score values during in-season compared to pre-season and the values were below the risk cut-off point reported in the literature. This group did not present substantial anterior distance asymmetry.

THE FRONTAL PLANE KNEE PROJECTION ANGLE IN ELITE MALE VOLLEYBALL ATHLETES IS INCREASED AFTER AN INCREMENTAL SHUTTLE RUN TEST UNTIL VOLUNTARY FATIGUE

Background Knee valgus is associated with non-contact anterior cruciate ligament rupture and this injury commonly occurs at the end of competition and/or training sessions. Probably, muscle fatigue is associated to this injury occurrence. Clinically, knee valgus is easily identified by the quantification of frontal plane knee projection angle (FPKPA). Objective The purpose of this study was to compare FPKPA before and after a maximal, incremental shuttle-run testing protocol used to induce fatigue in elite male volleyball athletes. Design Cross-sectional study. Setting Sports Sciences Laboratory at the Universidade Federal de Minas Gerais. Patients (or Participants) Thirteen elite male volleyball athletes with a mean age of 27.69 (+7.85) years, body mass of 92.00 (+8.97) kilograms and height of 1.94 (0.06) meters participated in a preseason assessment. Interventions (or Assessment of Risk Factors) Fatigue was induced by performing a maximal-incremental shuttle-run test for the estimation of maximal aerobic power according to the protocol proposed by Ramsbotton et al. (1988). Main Outcome Measurements FPKPA was measured during single-leg squat and involved a line connecting antero-superior iliac spine, a middle point between knee condyles and a middle point between the malleolus. The athletes performed 3 single-leg squats and a mean of the 3 FPKPA on the dominant lower limb was analyzed. Results The dominant lower limb had a mean FPKPA of 3,18 o (±4.23) prior to and a mean FPKPA of 3.73 o (±4.03) after the fatigue protocol. A Studens t-test analysis showed a statistical significant difference (p=0.019; mean difference=3.18; IC 95% of 0.62–5.74). Conclusions Elite male volleyball athletes had higher values of FPKPA on the dominant lower limb after a maximal, progressive exercise leading to fatigue. Probably, elite volleyball players may be under a higher risk of muscle-skeletal injuries under muscle fatigue conditions.