Evidence-Based Physical Therapy (EBP) uses the best research evidence with clinical expertise and user’s preferences to produce the most appropriate and effective care. At week 43 in 2023, we had Blended Intensive program (BIP) in Finland, Kuopio Savonia University of Applied Science about EBP. This BIP program opened with welcome words of the president of The European Network of Physiotherapy in Higher Education (ENPHE) and followed with the basis of EBP and teachers who highlighted the main challenges at different Physical Therapy fields week 43 in 2023 we had Blended Intensive program (BIP) in Finland, Kuopio Savonia University of applied science. More than 40 physiotherapy students and 7 teachers from three universities (Savonia University of Applied Sciences, Finland, Universidade da Coruña, Spain, and Charles University Prague, actively participated this week and shared experiential group dynamics and social activities. Students worked together and wrote articles devoted to the following themes: Evidence Based in McKenzie, back pain, spinal cord injuries, aquatic therapy, ergonomics at work, Nordic walking, sport injuries, sport and young adults: Prevention of sport injuries and children with disabilities. In the following you can consult the works presented by the students on each topic.

Anterior cruciate ligament (ACL)

The anterior cruciate ligament (ACL) is a band of dense connective tissue which courses from the femur to the tibia. The ACL is a structure in the knee joint, as it resists anterior tibial translation and rotational loads. (1) The anterior cruciate ligament originates at the medial wall of the lateral femoral condyle and inserts into the middle of the intercondylar area. It contributes significantly to the stabilization and kinematics of the knee joint. The femoral origin is oval and is located in the posterior aspect of the lateral femoral condyle. The position of the femoral origin is behind the centre of rotation of the knee joint; therefore, it becomes tense when the knee is extended. The tibial insertion is oval and its centre is nearly in the middle of the tibial plateau. (2)

Anterior cruciate ligament (ACL) injuries are the most common ligament injury of the knee. Approximately between 100,000 and 200,000 ACL injuries happen among athletes per year. ACL injuries occur either with contact or non-contact mechanisms. Contact injuries are more common in males meanwhile non-contact injuries are more common in females. ACL injuries normally require surgical reconstruction and have high re-rupture rates, as well as have long rehabilitation times. Most common mechanisms of ACL ruptures are decelerating, cutting and rotational movements, especially during landing. (3)

We found several articles regarding ACL injuries and sex differences. In the end we only chose articles which fit our criteria on was reliability and we compared many studies, however, it was particularly difficult to find evidence because it is currently being investigated and there is still not much evidence. In this article, we will discuss about the differences between men and women in ACL injuries. When we mention about men and women in this article, we only refer to the anatomical structure and biological gender. We do not speak out on how people define their own gender.

Anatomic factors

 Female injury rates per exposure are higher when compared to males, potentially due to anatomic differences of the lower kinematic chain, one of these being the Q angle. The Q angle, which is also known as quadriceps angle, is defined as the angle formed between the quadriceps muscles and the patella tendon. The wider the Q-angle the higher the risk to have ACL-injury. Larger Q angles increase the lateral pull of the quadriceps femoris muscle on the patella and put medial stress on the knee. Females usually have wider pelvis which increases the Q-angle. (4)  In 2023 a study was made to determine if different Q-angles in female alpine ski racers differentially affect which ligaments in the knee are more likely to be torn, as well as the frequency of ligament tears occurring at different levels of competition. The result is that larger Q- angles influence the risk of injury as well as injury to specific ligaments within the knee. (5)

In 2020 it was investigated if the ACL attachment location differed between men and women as well as if it was a factor to why women are more prone to tear their ACL. The study is a cross-sectional study where MRI images of the knees of 90 patients with ruptured ACLs and 90 non-contact knee injuries without ACL ruptures was investigated. Turns out that no significant differences between female and male participants regarding ACL attachment location was found. Patients with a ruptured ACL had a significantly different ACL origin compared to patients with an intact ACL by an average difference of 8.9% more posterior and 4.0% more proximal in men and 13% posterior and 5.5 % proximal to the sagittal axis of the knee in women. The ACL attachment location shouldn’t be considered as a risk factor for the increased ACL rupture rates in female compared with male athletes. However, the more posterior and proximal location of the femoral ACL attachment origin might predispose to an ACL rupture regardless of gender. (6)

Biomechanical factors

Dynamic knee valgus is associated with an increased risk of non-contact anterior cruciate ligament injury. Dynamic knee valgus places significant tensile forces on the ACL specially during landing and cutting. Partly due to wider hips, knee valgus is more common in women than in men (Kapandji 1997). Females also typically do not generate as much force as male counterparts in the hip abductors, thus potentially subjecting them to dynamic knee valgus moments. 3 These anatomic differences make them to activate much more the quadriceps muscles, developing a higher muscle fatigue, rising the risk of knee injuries. Core proprioception and stability has been related to ACL injuries, and bad trunk kinetics can augur knee injuries in women, but it is less frequent in men. (7)

Hormones and menstrual cycle

Some studies reported that estrogen and progesterone receptor sites exist in human ACL cells, suggesting that female sex hormones may play a role in the ACL’s structure and composition. 8 They also found that levels of estradiol have a significant dose-dependent effect on the fibroblasts of the ACL. Collagen, produced by fibroblasts, is known to perform the major load-bearing function of the ACL and perhaps alterations in the metabolism of these fibroblasts influence the quantity, type, and stability of the collagen in the anterior cruciate ligament. The resulting structural and compositional changes in these fibroblasts could result in reduced strength of the anterior cruciate ligament, predisposing female athletes to ligamentous injury. (8)

Social and environmental factors

The traditional paradigm for ACL injuries only includes the aforementioned factors and differences; nevertheless, annual ACL injury rates in the general population have remained unchanged in females while they have decreased among males, suggesting that strictly biological explanations may not be enough in order to improve this outcome for females. There are different social-influenced environments that surround female athletes and have recently been proven to have an impact on their ACL injury risk. For example, in pre-sport environment, mothers tend to underestimate the crawling abilities of daughters and overestimate their son´s abilities, which impacts as a difference in sports and physical abilities while growing up. About the training environment, studies show that female athletes have affirmed to hold back during training sessions because becoming too “bulky” concerns them, as it is not as socially accepted as a lean body. In more than 20 years of research about sex-related factors in ACL injuries, it has failed in decreasing these rates for females; so it is needed to have a more holistic approach about it. (7,8)

Conclusion

 The past 20 years of research have proven that sex-related biological factors influence and difference the risks of ACL injuries and its rates. However, social factors must also be included and taken into account in these researches in order to improve the difference in statistics between women and men. These social and environmental factors are a hot topic nowadays and the last ACL-related studies focus on them, so we hope that in the next years these ratings improve.

What we learned this week/comparing the differences between our countries

In Finland, the curriculum of physiotherapy students does not include lessons about the effects the menstrual cycle or hormones have on tendons and ligaments. The correlation between the menstrual cycle and ACL injuries was new information for the Finnish students. We noticed that this is one of the many differences between our study programs. Working together was rewarding and we gained more information about sport injuries with ACL and how they are supposed to be observed in a wider perspective. Spanish students have learned more about different databases apart from PubMED, which is the most popular in the country, such as Cochrane or PEDro, and we have not used any other before. In addition, we have deepened our knowledge the environmental and social factors.

Authers:

Rivada López Noa Physiotherapy student, Universidade da Coruña, Spain

Busto Acedo Melania Physiotherapy student, Universidade da Coruña, Spain

Otero Fraga Pablo Physiotherapy student, Universidade da Coruña, Spain

Haukka Sonja-Susanna Physiotherapy student, Savonia University of Applied Sciences, Kuopio, Finland

Hyvärinen, Johanna Physiotherapy student, Savonia University of Applied Sciences, Kuopio, Finland

Lehtinen Maiju Physiotherapy student, Savonia University of Applied Sciences, Kuopio, Finland

Marja Äijö, PhD, PhD, Principal lecturer of gerontology and rehabilitation, Savonia University of Applied Sciences, Finland

Mari Tuppurainen, physiotherapy lecture, Savonia University of Applied Sciences, Kuopio, Finland

Dagmar Pavlu, Physiotherapist, Assoc. Prof. Charles University, Czech Republic

Ivana Vláčilová, Professor, Charles University, Czech Republic

Jamile Vivas Costa, PhD, MSc, PT. Lecturer at Department of Physical Therapy, Medicine and Biomedical Sciences, Faculty of Physiotherapy and Researcher at Psychosocial intervention and functional rehabilitation group, Universidade da Coruña, Spain

Montserrat Fernández Pereira, MSc, PT.  Lecturer at Department of Physical Therapy, Medicine and Biomedical Sciences, Faculty of Physiotherapy and Physiotherapist at Spinal Cord Injury Unit, A Coruña Hospital (CHUAC), Spain

Verónica Robles García, PhD, MSc, PT, OT. Lecturer at Department of Physical Therapy, Medicine and Biomedical Sciences, Faculty of Physiotherapy and Researcher at the Neuroscience and motor control group, Universidade da Coruña and Biomedical Institute of A Coruña, Spain

References:

1. Duthon VB, Barea C, Abrassart S, Fasel JH, Fritschy D, Ménétrey J. Anatomy of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc. 2006 Mar;14(3):204-13. doi: 10.1007/s00167-005-0679-9. Epub 2005 Oct 19. PMID: 16235056.

2. Petersen W, Tillmann B. Anatomie und Funktion des vorderen Kreuzbandes [Anatomy and function of the anterior cruciate ligament]. Orthopade. 2002 Aug;31(8):710-8. German. doi: 10.1007/s00132-002-0330-0. PMID: 12426749

3. Boniello, Michael, Chafetz, Ross, Franklin, Corinna, Larwa, Joseph & Stoy, Conrad 2021. Stiff Landings, Core Stability, and Dynamic Knee Valgus: A Systematic Review on Documented Anterior Cruciate Ligament Ruptures in Male and Female Athletes. International Journal of Environmental Research and Public Health 18 (7). 10.3390/ijerph18073826.

4. Liukkonen, Irmeli, Saarikoski, Riitta & Ahonen, Jarmo 2004. Jalat ja terveys. Helsinki: Duodecim.

5. Taylor, Danielle & Bevier, Catherine 2023. Relationships Among Knee Injuries, Q-angles, and Competition Levels in Female Ski Racers. MedRxiv. https://doi.org/10.1101/2023.09.14.23295552.

6. Dimitriou, Dimitris, Helmy, Naeder, Tsai, Tsung-Yuan, Wang, Zhongzheng & Zou, Diyang 2020. Do Sex-Specific Differences Exist in ACL Attachment Location? The Orthopaedic Journal of Sports Medicine 8 (11). 10.1177/2325967120964477

7. Acevedo, Rafael J. MD; Rivera-Vega, Alexandra MD; Miranda, Gerardo MD; Micheo, William MD, FACSM 13(3):p 186-191, May/June2014.

8. Parsons JL, Coen SE, Bekker S. Anterior cruciate ligament injury: towards a gendered environmental approach. British Journal of Sports Medicine 2021;55:984-990

9. Kapandji, I. A. 1997. Kinesiologia II. Alaraajojen nivelten toiminta. Medirehab kirja- kustannus. Laukaa. 10. Magee, David 2008. Orthopedic Physical Assessment.

11. Park J-G, Han S-B, Lee C-S, Jeon OH, Jang K-M. Anatomy, Biomechanics, and Reconstruction of the Anterolateral Ligament of the Knee Joint. Medicina. 2022; 58(6):786. https://doi.org/10.3390/medicina58060786