Ultrasonography and clinical examination of knee injuries in pre- and post- menarche dancers

Patellofemoral pain and musculoskeletal features in young pre- and post-pubertal female dancers

The aim of this study was to examine associations between patellofemoral pain (PFP) and musculoskeletal features (such as tendon structure and bone properties) in young (pre- and post-pubertal) female dancers. A total of 49 dancers participated in this study (mean age 13.6 ± 2.9; weight 47.0 ± 13.2; height 153.7 ± 12.9 and body mass index (BMI) 19.4 ± 3.1) and were assessed for the following factors: dance background and Tanner stage through interviews; ultrasonography assessments of bone properties and patellar tendon structure through ultrasonographic tissue characterization and quantitative ultrasound, respectively; and anthropometric measurements, muscle strength, range of motion (ROM), hypermobility and PFP through physical examinations. PFP was found in 49% of the participants. Post-pubertal dancers with no-PFP were found to have greater muscle strength, greater radial and tibial properties, and better tendon structure compared to pre-pubertal dancers with PFP and compared to pre-pubertal dancers with no-PFP [F(2, 41) = 18.64, p < .001; F(2, 41) = 20.46, p < .001; F(2, 41) = 33.06, p < .001; and, F(2, 41) = 6.02, p = .007, respectively]. Logistic regression showed that tibial bone properties and range of movement (ROM) in hip external rotation were significantly associated with PFP [odds ratio (OR) = .889 and OR = 2.653, respectively; Cox & Snell R2 = .701]. The study revealed a high prevalence of PFP among young dancers, with low bone properties and hyperjoint ROM emerging as the main factors that are related to PFP. These findings should be addressed by medical teams, athletic trainers, and dance teachers regarding the need for implementing modifications to dance training programmes and injury-prevention strategies in young pre-pubertal dancers.

Is there an association between joint range of motion and muscle strength in young female dancers? And, does it depend on the effects of age and menarche?

Aiming to determine the association between joint range of motion (ROM) and muscle strength; and, the effect of age and menarche on those two factors; 132 pre-and post-menarche dancers, aged 12-14 years were assessed for joint ROM and for muscle strength at the hip, knee and ankle and foot joints. En-pointe ROM was significantly correlated with ankle plantar-flexors' (r = -.184) and with ankle dorsiflexors' muscle strength (r = -.221). Hip external rotation ROM was significantly correlated with knee extensors' strength (r = -.263). Pre-menarche dancers had higher joint ROM compared with post-menarche dancers; yet, dancers at post-menarche were stronger compared to dancers at pre-menarche. The slope coefficient was negative at the age of 12 in hip external rotation and in en-pointe (-0.80 and -0.52, respectively) and became steeper with age (age 13: -3.52 and -3.28, respectively; age 14: -6.31 and -4.42, respectively). Along maturation, dancers with high joints ROM showed reduced muscle strength. Pre-menarche dancers have higher joint ROM, yet reduced muscle strength, compared with post-menarche dancers. As the association between joint ROM and muscle strength might be involved with growth and development, young dancers should be screened along pubertal stages in order to decide the correct curricula and to prevent future injuries.

Injury Rates and Characteristics Associated with Participation in Organized Dance Education: A Systematic Review

INTRODUCTION

Several studies and recent systematic reviews have investigated injury in dance settings and have largely focused on specific concert dance genres (i.e., ballet, contemporary) and elite levels (i.e., pre-professional, professional) of dance. Less is known about the health of those who participate in dance education settings, namely teachers and students from private dance studios. Given that these individuals constitute a large proportion of the dance community, greater clarity of risks in the dance training environment could benefit an underserved majority by informing the development of effective injury prevention strategies.<br/> Objective: The primary objective was to describe injury rates and characteristics associated with participation in organized dance education settings.<br/> Methods: Six electronic databases were searched to April 2021 (Medline, EMBASE, SportDiscus, CINAHL, SCOPUS, Cochrane). Selected studies met a priori inclusion criteria that required original data from dance teacher and student samples within formal dance education settings. All genres of dance were eligible. Studies were excluded if no injury outcomes or estimates of dance exposure were reported, if injuries occurred during rehearsal and performance, or if dance was used as a therapeutic intervention or exercise. Two reviewers independently assessed each paper for inclusion at abstract and full text screening stages. The quality of included studies was assessed using the Joanna Briggs Institute Level of Evidence tool.<br/> Results: The initial database search identified 1,424 potentially relevant records, 26 were included and scored. Most studies (n = 22) focused on dance students only, three included only dance teachers, and one study included both. Among both dance students and teachers, the majority of injuries reported were overuse or chronic and involved the lower limb. For studies that reported injury rates (n = 14), estimates ranged from 0.8 to 4.7 injuries per 1,000 dance hours, 4.86 per 1,000 dancer-days, and 0.21 to 0.34 per 1,000 dance exposures.<br/> Conclusions: Based on the current research, dance students and teachers experience a similar rate of injury to concert and professional dancers, and their injuries are most commonly overuse injuries involving the lower extremity. There have been few high-quality investigations of injury specific to the dance training environment. Therefore, consensus around the burden of injury in the dance education settings remains difficult. Future dance epidemiological investigations that examine the burden of injury among dance teachers and students, include operational injury and exposure definitions, and utilize prospective designs are warranted.

Physical Activity and Investigation With Magnetic Resonance Imaging Partly Explain Variability in the Prevalence of Patellar Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals

OBJECTIVE

To estimate the pooled prevalence of, and factors associated with, the presence of patellar tendon abnormalities observed on imaging in people without symptoms.

DESIGN

Systematic review with stratified meta-analysis and meta-regression.

LITERATURE SEARCH

We searched Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science from 1980 to August 2020.

STUDY SELECTION CRITERIA

We included studies that reported the prevalence of asymptomatic patellar tendon abnormalities on imaging. We excluded studies of participants with current tendon pain, a history of tendon pain, or other systemic conditions.

DATA SYNTHESIS

Stratification and meta-regression of studies based on study-level descriptive statistics (mean age, body mass index, proportion of female participants, physical activity participation, imaging modality) were performed using a random-effects model to account for between-study heterogeneity. Risk of bias was assessed using the modified Newcastle-Ottawa scale.

RESULTS

Meta-analysis of 64 studies (7125 limbs from 4616 participants) found significant between-study heterogeneity (I²≥90%, P<.01), which precluded a summary prevalence estimate. Heterogeneity was partially explained by studies that included participants who were physically active and studies that assessed tendon abnormalities using magnetic resonance imaging compared to ultrasound (P<.05). Mean age, body mass index, proportion of female participants, and sample size did not explain the remaining heterogeneity.

CONCLUSION

There was substantial variability in the reported prevalence of asymptomatic patellar tendon abnormalities. A clear and valid method is needed to assess and report the presence of patellar tendon abnormalities to increase research capacity and establish the clinical value of imaging the patellar tendon. J Orthop Sports Phys Ther 2021;51(5):216-231. Epub 28 Mar 2021. doi:10.2519/jospt.2021.10054.

Generalized joint hypermobility, scoliosis, patellofemoral pain, and physical abilities in young dancers

Background

Many young girls with generalized joint hypermobility (GJH) choose to participate in dance because their bodies are suited for this activity. Scoliosis tends to occur often in thin girls, who also are more likely to choose dance. Both anomalies (GJH and scoliosis) may be related to reduced abilities such as diminished strength and insufficient postural balance, with increased risk for musculoskeletal conditions. The main objectives of the present study were to determine the prevalence of dancers with GJH, the prevalence of dancers with scoliosis, and the prevalence of dancers with these two anomalies; and, to determine differences in physical abilities and the presence of patellofemoral pain (PFP) between young female dancers with and without such anomalies.

Methods

One hundred thirty-two female dancers, aged 12–14 years, were assessed for anthropometric parameters, GJH, scoliosis, knee muscle strength, postural balance, proprioception ability, and PFP.

Results

GJH was identified in 54 dancers (40.9%) and scoliosis in 38 dancers (28.8%). Significant differences were found in the proportion of dancers with no anomalies (74 dancers, 56.1%) and dancers with both anomalies (34 dancers, 25.8%) (p < .001). Dancers with both anomalies had reduced dynamic postural balance in the anterior direction (p = .023), reduced proprioception ability (p < .001), and weaker knee extensors (p = .036) and flexors (p = .040) compared with dancers with no anomalies. Among dancers with both anomalies, 73.5% suffered bilateral PFP, 17.6% suffered unilateral PFP, and 8.8% had no PFP (p < .001).

Conclusions

A high prevalence of young girls participating in dance classes had GJH, as the increased joint flexibility probably provides them with some esthetic advantages. The high prevalence of scoliosis found in these young dancers might be attributed to their relatively low body mass, their delayed maturation, and the selection process of dancers. Dancers with both GJH and scoliosis had decreased muscle strength, reduced postural balance, reduced proprioception, with higher risk of PFP. The main clinical implications are the need to reduce the risk of PFP among dancers by developing appropriate strength and stabilizing exercises combined with proprioceptive and postural balance training, to improve the correct alignment of the hyperextended and hypermobile joints, and to improve their supporting muscle strength.

An exploratory study of the use of ultrasound in the measurement of anterior tibial translation under gastrocnemius muscle stimulation

Gastrocnemius' role as an agonist or antagonist of the anterior cruciate ligament (ACL) is not well understood. This study explored the use of ultrasound imaging to investigate how gastrocnemius stimulation levels influenced anterior tibial translation. The gastrocnemii of 10 participants were stimulated to four different levels using electrical muscle stimulation. The quadriceps were co-activated at a fixed level. Anterior tibial translation was determined using ultrasound imaging. Intraclass correlation coefficient [ICC (2,1)] was used to assess the intra-rater reliability over two sessions. Intra-rater reliability was good at rest and under most muscle stimulation levels (ICC = 0.84 to 0.92), and moderate with the lowest (ICC = 0.71) and highest stimulation (ICC = 0.61). While anterior tibial translation was not significantly different across simulation levels, ultrasound imaging recorded the anterior movement of the tibia as the gastrocnemius was activated, thus supporting gastrocnemius' role as an antagonist of the ACL.

Can young dancers skip/recover from patellofemoral pain? A two-year follow-up

Aiming to follow the prevalence of patellofemoral pain (PFP) among young dancers over 2-years, and to assess the prevalence of re-injured/recovered dancers; 67 dancers (aged 12.8 ± 0.5) were screened for PFP at baseline, 65 dancers at 1^st follow-up and 51 dancers at 2^nd follow-up. All dancers (46) that took part in all the 3 screenings had at least one episode of PFP along the screenings. No dancers recovered in the 1^st follow-up, yet 40.5% of the dancers with PFP at the 1^st follow-up recovered in the 2^nd follow-up. Along the 3 screenings, 23.9%, 34.8%, and 41.3% of the dancers had 1,2 or 3 PFP episodes, respectively. None of the dancers skipped PFP along the 3 screenings. A high prevalence of dancers had sustained PFP along the 2 follow-ups, with low recovery rate. Dancers and teachers should be alert to the need for devising modifications of training and injury prevention strategies from young age.

Unilateral and bilateral patellofemoral pain in young female dancers: Associated factors

Aiming to evaluate the prevalence of unilateral/bilateral patellofemoral pain (PFP) among young dancers, and to investigate whether different factors are associated with PFP in young dancers, 132 dancers aged 12-14 years were assessed for PFP. Anthropometric parameters, proprioception ability, dynamic postural balance (DPB), and muscle strength were measured. PFP was found in 64.1% of the dancers. No significant differences in the prevalence of dancers with no, unilateral, or bilateral PFP at different ages were found. Significant age effects were found for anthropometric and developmental measurements, and for intensity of training. PFP effect was found for DPB asymmetry, ankle proprioception, and leg-length %height. A higher hip abductor/adductor ratio was associated with PFP in 14-year-old dancers. Binomial logistic regression showed that increased number of hours per day (h/day) and decreased number of hours per week (h/week), low proprioception scores, greater leg length as %height, and more anterior DPB asymmetry were significant predictors of PFP. In conclusion: unilateral/bilateral PFP is common among young dancers. Body morphology, reduced ankle proprioception ability, DPB asymmetry, and increased h/day of practice are associated with PFP. Dance teachers should start monitoring the impact of training and implement injury modification/prevention strategies when their students are at a young age.

Isometric exercises and somatosensory training as intervention programmes for patellofemoral pain in young dancers

Patellofemoral pain (PPF) is a common problem experienced by young dancers. Currently, there is no clear indication as to the optimal intervention programme for reducing the level of pain and improving functional abilities in young dancers with PFP. Our aim was to examine the efficacy of two intervention programmes compared with controls in relation to PFP symptoms (shown by pain level, Grinding test, and patellar inhibition test-PIT) and functional abilities of dancers with PFP. Ninety-eight young dancers (mean age 13.4 ± .97) with PFP were assessed for clinical parameters and functional abilities pre and post an intervention programme lasting 12 weeks. Using cluster sampling controlling for grade and school, the dancers were divided into three groups: isometric exercises (IE), somatosensory training (ST), and control (CO). Post-intervention, significantly lower pain levels upon patellar provocation testing were reported for the two treatment groups compared with controls. There was a significantly lower rate of legs recovered in the CO group compared with both intervention groups on the Grinding test, and on the PIT. Postural balance ability and proprioception abilities were significantly better post-treatment for the two treatment groups compared with controls. A significant interaction showed that hip abduction muscle strength improved more in the IE group. In conclusion, both isometric exercises and somatosensory training were effective for decreasing clinical symptoms and improving some functional abilities in young dancers with PFP. Further studies on these types of interventions could determine the most effective training protocol for prevention and treatment of PFP in young dancers.

Patellofemoral pain, body morphology and alignment in female pubertal dancers: One-year follow-up

The aim of this study was to assess changes in body morphology, anatomical alignment and prevalence of patellofemoral pain (PFP) in young female dancers along one year of pubertal growth, and to identify the risk factors related to PFP in these young dancers. Both legs of 60 dancers were evaluated during grade 7 and again after 1-year. At each of these points in time, the dancers were interviewed concerning their background, and anthropometric measurements, lower-limb physical examinations and knee ultrasound scans were performed. Morphological parameters changed significantly from baseline to follow-up. PFP was found in 53.3% of the dancers' knees at baseline. At follow-up, 55.4% of the asymptomatic knees at baseline developed PFP, and only 9.4% of the symptomatic knees at baseline recovered. Lower BMI was identified among dancers who developed PFP during follow-up compared with dancers with no PFP, either at baseline or at follow-up. A positive grinding and positive Patellar Inhibition Test (PIT) were found to be risk factors for PFP at follow-up. A high prevalence of young dancers suffered PFP, from injuries they sustained mostly during the 1-year of dance practice. Parameters predisposing the dancers to PFP should be identified at early stages of dance class.