"When you're down, stay down": A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

Tumor-Like Distal Femoral Cortical Irregularities of the Knee in Adolescent Competitive Alpine Skiers: Longitudinal Assessment Over 48 Months

BACKGROUND

Tumor-like distal femoral cortical irregularities (DFCIs) are a frequent incidental finding on knee magnetic resonance imaging (MRI) and are common in young competitive athletes.

PURPOSE

To assess and compare the morphology and prevalence of DFCIs in competitive alpine skiers over 48 months during adolescence.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Adolescent competitive alpine skiers were prospectively recruited in 2018 and received bilateral 3-T MRI of the knee at baseline and after 48 months. All MRIs were evaluated for the presence and location of DFCIs, which were marked at 1 of 3 anatomic positions: (1) the femoral attachment of the medial head of the gastrocnemius muscle, (2) the lateral head of the gastrocnemius muscle, or (3) the attachment of the adductor magnus aponeurosis. The size of the DFCI was measured by 2 radiologists independently. The measurements were compared using the Wilcoxon signed-rank test, the interclass correlation coefficient (ICC), and Cohen Kappa.

RESULTS

A total of 63 athletes (mean age at follow-up, 19.6 ± 1.2 years; n = 25 female) were included in the study. At baseline, DFCIs were detected in 84 out of 126 knees (67%). At the 48-month follow-up, DFCIs were found in 88 out of 126 knees (70%), with multiple DFCIs in 3 knees and no significant difference between male and female patients (n = 24 male, n = 19 female; P = .71). No significant increase was detected for the number (P = .21) and size of the DFCIs between the baseline and the 48-month follow-up (mean size: baseline, 3.7 ± 0.8 mm; 48-month follow-up: 3.6 ± 0.9 mm; P = .66). The interrater agreement for the mean size measurements of DFCIs was good to excellent (ICC 0.88).

CONCLUSION

DFCIs remain a frequent finding on knee MRI in competitive alpine skiers after skeletal maturation and do not disappear during adolescence. The DFCI size was constant in athletes aged between 15 and 19 years. Moreover, DFCIs should not be mistaken for a pathologic finding.

Superolateral Hoffa fat pad edema in adolescent competitive alpine skiers: temporal evolution over 4 years and risk factors

OBJECTIVES

To longitudinally assess and correlate the prevalence of superolateral Hoffa fat pad (SHFP) edema with changes in features of the knee extensor mechanism in adolescent competitive alpine skiers over 48 months.

METHODS

Competitive alpine skiers were prospectively enrolled in 2018 and underwent bilateral knee MRI at baseline and after 48 months. MRI was assessed for the prevalence of SHFP edema. Features of the knee extensor mechanism were assessed by measuring the trochlear sulcus angle and depth, lateral and medial trochlear inclination, trochlear angle, patella tilt, Insall‒Salvati ratio (ISR), and patellar ligament to lateral trochlear facet (PL-T) distance. Separate logistic regression models were used to calculate the odds ratios between each measurement and the presence of SHFP edema at both time points.

RESULTS

Sixty-three athletes were included in the study (mean age 15.3 ± 1.3 years, 25 women). At baseline, 23 knees had SHFP edema, increasing to 34 knees at the 48-month follow-up. At baseline, knees with measurements in the highest quartile for ISR and lowest quartile for trochlear depth and PL-T were 9.3, 5.1, and 7.7 times more likely to show SHFP edema, respectively. At follow-up, these correlations were confirmed and additionally, knees with measurements in the highest quartile for trochlear sulcus angle and the lowest quartile for lateral trochlear inclination were 4.1 and 3.4 times more likely to show SHFP edema.

CONCLUSION

An increased prevalence of SHFP edema in competitive alpine skiers during adolescence was associated with persistent high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet.

CRITICAL RELEVANCE STATEMENT

In clinical routine, assessment of the mechanical properties of the knee extensor mechanism, together with anatomical developments during adolescence, may improve the understanding and management of patellofemoral instability.

KEY POINTS

• Superolateral Hoffa fat pad (SHFP) edema is a frequent cause of anterolateral knee pain but the role of predisposing factors is still debated. • A higher prevalence of SHFP edema was associated with high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet. • Understanding of the mechanical interaction and the anatomical development of the knee during adolescence provides further insight into the development of SHFP edema.

We know a lot about little and little about a lot: A contextualized scoping review on injury prevention in alpine ski racing

BACKGROUND

Our goal was to summarize and contextualize the available literature on alpine ski racing injury epidemiology, injury etiology, injury prevention measures, injury prevention context, and implementation issues.

MATERIALS AND METHODS

We searched four electronic databases using predetermined search terms. We included original studies that assessed injury, injury risk factors, and injury mechanisms, and assessed and reported the effect of an injury prevention measure in alpine ski racing. Two authors independently conducted title-abstract screening, and one performed the full-text review. For data synthesis and categorization, we used the Translating Research into the Injury Prevention Practice framework and a modified and adapted version of the Haddon matrix.

RESULTS

Of the 157 included studies, most corresponded to injury epidemiology and etiology, whereas few studies encompassed injury prevention measure development, implementation and evaluation. Preventive interventions targeting equipment, rules and regulations, course design and snow preparation were the most prevalent in the literature. Furthermore, various contextual factors in the current literature have been found, including gender, competition level, countries and federations, and time periods within a season.

CONCLUSIONS

We provided an in-depth and comprehensive overview of the current state-of-the-art in the alpine ski racing context. We know a lot about little and little about a lot across all the areas associated with injury prevention in such context. The limitations in the literature yield a road map for designing future injury prevention studies to address the key gaps identified. A more comprehensive context-driven approach throughout all stages of injury prevention would benefit the ultimate implementation of effective preventive strategies.

Addressing the unresolved challenge of quantifying skiing exposure-A proof of concept using smartphone sensors

In epidemiological studies related to winter sports, especially alpine skiing, an unresolved methodological challenge is the quantification of actual on-snow activity exposure. Such information would be relevant for reporting meaningful measures of injury incidence, which refers to the number of new injuries that occur in a given population and time period. Accordingly, accurate determination of the denominator, i.e., actual "activity exposure time", is critical for injury surveillance and reporting. In this perspective article, we explore the question of whether wearable sensors in combination with mHealth applications are suitable tools to accurately quantify the periods in a ski day when the skier is physically skiing and not resting or using a mechanical means of transport. As a first proof of concept, we present exemplary data from a youth competitive alpine skier who wore his smartphone with embedded sensors on his body on several ski days during one winter season. We compared these data to self-reported estimates of ski exposure, as used in athletes' training diaries. In summary, quantifying on-snow activity exposure in alpine skiing using sensor data from smartphones is technically feasible. For example, the sensors could be used to track ski training sessions, estimate the actual time spent skiing, and even quantify the number of runs and turns made as long as the smartphone is worn. Such data could be very useful in determining actual exposure time in the context of injury surveillance and could prove valuable for effective stress management and injury prevention in athletes.

Altered regional 3D shear wave velocity patterns in youth competitive alpine skiers suffering from patellar tendon complaints - A prospective case-control study

AbstractPatellar tendon (PT) complaints are frequent throughout the population, with increased occurrence in athletes and, particularly, in youth competitive alpine skiers. Timely detection and treatment might improve prospects of recovery. Diagnostic modalities in clinical use to date rely on pain symptoms, manual palpation, and potentially, magnetic resonance imaging (MRI); however, MRI-based imaging yields limited sensitivity. Quantitatively measuring the morphological and mechanical properties of PTs by means of B-mode ultrasound and shear wave elastography (SWE), instead, may allow improved diagnosis or even early detection. We performed B-mode scans and three-dimensional ultrasound shear wave velocity (SWV) mapping and MRI of the PT in 106 youth skiers. A prospective one-year survey on health problems combined with clinical assessments served to categorize symptomatic and asymptomatic youth skiers. Skiers suffering from distal or proximal tendon complaints showed lower SWV in the respective tendon region than asymptomatic skiers (p = 0.035 and p = 0.019, respectively). Youth skiers with distal tendon complaints additionally exhibited decreased SWV in the proximal region compared to asymptomatic counterparts (p = 0.020). Cross-validated analysis of retrospective prediction indicated sensitivity and specificity in detecting tendon complaints in the range of 0.606-0.621 and 0.536-0.650, respectively. MRI detected distal tendon complaints with a sensitivity of 0.410 (12/29) but failed to detect any proximal cases. This study agrees with the most recent literature in that SWE holds promise as a valuable adjunct modality for the diagnosis of PT complaints or even the detection of subclinical prestages. However, to evaluate its prospective predictive value, long-term studies are warranted.

Screening Tests for Assessing Athletes at Risk of ACL Injury or Reinjury-A Scoping Review

Various tests are available to assess athletes for factors associated with their susceptibility and risk of anterior cruciate ligament (ACL) injury or reinjury; however, it is unclear which tests are clinically meaningful and what should be considered when using them. Therefore, the aim of this scoping review was to screen and summarize testing and to derive evidence-based recommendations for clinicians, practitioners and future research. Five databases were searched to identify studies addressing musculoskeletal morphology or functional-performance-related screening tests with a clear conceptual link or an evidence-based relationship to ACL (re)injury. A quality rating was carried out using the National Institutes of Health (NIH) Study-Quality Assessment Tool. Six different categories of common screening tests were identified: balance and postural control, gait- and running-related tests, joint laxity, joint morphology and anthropometrics, jump tests and strength tests. Predicting future injury in a complex, dynamic system based on a single screening test is methodologically challenging, which is also reflected in the highly controversial findings in the literature regarding potential associations between specific screening tests and the occurrence of ACL injuries and reinjuries. Nonetheless, various screening tests can provide clinically relevant information on ACL-(re)injury-related factors and help to provide tailored preventive measures. A selection of corresponding evidence-based recommendations is derived and presented in this scoping review.

Deadbug Bridging Performance in 6- to 15-Year-Old Competitive Alpine Skiers—A Cross-Sectional Study

Simple Summary

In competitive alpine skiing, a stable trunk plays an important role in increasing performance and preventing injuries. The aim of the present study was to investigate the ability to stabilize the trunk during so-called deadbug bridging (DBB) exercises, a stabilizing, dynamic movement task in the supine position with the pelvis lifted and unilateral leg raising, in 6- to 15-year-old skiers. Trunk stabilization performance was better in female skiers of the under 15-year (U15) category than in their male counterparts, whereas there was no sex difference at ages under 10 years (U10). The only potential confounder when testing youth skiers revealed being body height, but only in female U10 skiers. In summary, this study provided sport-specific normative reference data that may be of equal interest to both researchers and sport practitioners.

Abstract

In competitive alpine skiing, a superior antirotation and rear-chain stabilization capacity is essential to constantly remain in dynamic equilibrium while skiing and to counteract the ski-specific adverse loading patterns of the back. As such, skiers’ trunk stabilization performance during deadbug bridging (DBB) exercises has been shown to be associated with both skiing performance and overuse complaints of the lower back in skiers under 16 years of age (U16). However, to date, little is known about the corresponding stabilization abilities in younger skiers, i.e., 6- to 15-year-old skiers. As part of a biomechanical field experiment during a national off-snow fitness competition, a total of 101 youth competitive alpine skiers were tested with respect to their trunk stabilization performance during DDB exercise. The maximum contralateral displacement of the pelvic drop during leg lift (DBB_displacement) was quantified using reflective markers and a motion capture system (Vicon, Oxford, UK). Potential age group and sex differences in DBB_displacement were assessed using analysis of variance (ANOVA) at p < 0.05. Within each subgroup, the associations of DBB_displacement with age, anthropometrics and maturity offset were analysed using Pearson’s correlation (p < 0.05). Female skiers under 15 years of age (U15) showed better DBB performance than male U15 skiers, while there was no sex difference at the under 10-year (U10) level. In female U10 skiers, DBB_displacement was moderately associated with body height, while in all other subgroups, no confounding associations with anthropometrics or biological maturation were found. Biomechanically quantifying DBB performance may be considered a feasible and nonconfounded screening test approach in young skiers older than 6 years. Body height may represent a confounding bias in exclusively the U10 female skier cohort and, therefore, should be considered when interpreting the test results. In summary, this study provided sport-specific normative reference data that may be of equal interest to both researchers and sport practitioners.