Ultrasound measurement comparison of distal femoral cartilage thickness and hardness between amateur ballet dancers and healthy volunteers

Sakiko Ito (Onishi), Hiroki Saito, Takahiro Otsudo
Purpose:

his study aimed to compare the characteristics of hardness and thickness of distal femoral cartilage and its relationship for laxity, flexibility, and knee strengthening between amateur ballet dancers and healthy volunteers.

Methods:

 Eight female amateur ballet dancers (mean, 21.3 ± 0.7 years old, height: 159.5 ± 7.1 cm, weight: 48.6 ± 7.0 kg) and eight healthy females (mean, 21.0 ± 0.0 years old, height: 159.5 ± 5.3 cm, weight: 50.1 ± 5.3 kg) participated in this study. Thickness (mm) and elasticity (kPa) of bilateral distal femoral cartilage were measured using ultrasound real-time tissue elastography (EPIQ Elite nSight Plus, Philips, Nederland). In addition, hardness of the iliotibial band (kPa), laxity (Beighton method; point), femoral-tibia angle (°), knee strength (extension, flexion; N), and range of motion (knee extension, ankle dorsiflexion, plantar flexion; °) were also measured. Non-paired t-test was performed for statistical analysis, and the significance level was set at 0.05.

Results:

The range of left ankle plantar flexion in amateur ballet dancers was significantly larger (76.3±4.4) than in healthy volunteers (68.1±5.3)(P=0.01). The hardness of right knee cartilage in amateur ballet dancers was significantly lower (41.1±9.1) than in healthy volunteers (56.1±12.1)(P=0.01).

Conclusion(s):

The hardness of right knee cartilage in amateur ballet dancers was lower, and ranges of left ankle plantar flexion were larger than in healthy volunteers, while there was no significant difference in cartilage thickness and knee valgus angle between amateur ballet dancers and healthy volunteers. A previous study reported that females had thinner cartilage than males, whilst there was no correlation with body weight (Bedewi MA et al., 2020). In the case of ballet dancers, asymmetry of physical characteristics was correlated with self-reported musculoskeletal injuries (Pavlović M, et al., 2022). From these results, it was assumed that asymmetry in mechanical stimuli for the knee may be present in ballet dancers due to their daily training, and the hardness of cartilage measured by elastography may be useful in medical checks to prevent knee injury.

Implications:

This study revealed asymmetry in the hardness of knee cartilage in ballet dancers compared with healthy volunteers. Therefore, an appropriate training protocol may contribute to preventing knee injuries in ballet dancers.

Funding acknowledgements:
We have no funding acknowledgment in this study.
Keywords:
ballet dancer
hardness of cartilage
elastography
Primary topic:
Sport and sports injuries
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Institution: Tokyo University of Technology Ethics Committee: Tokyo University of Technology
Provide the ethics approval number:
Ethics Number: E23HS-022
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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