Is it a Myth or Reality? Knee Injuries in Female Firefighters

By: Trent Nessler, PT, MPT, DPT, SVP, Ready Rebound Vitality

When looking at injuries among firefighters over the last decade, we have seen a gradual decline in overall injuries (NFPA – Firefighter Injuries on the Fireground 2022). When looking at musculoskeletal injuries specifically, most might think that low back injuries account for the majority of recorded injuries. However, the lower extremity accounts for 19% of recorded injuries with the upper extremity accounting for 17%, the shoulder 12%, and the spine accounting for 3% (NFPA – Firefighter Injuries on the Fireground 2022). When looking at lower extremity injuries, the knee is the most injured joint.

Although female firefighters only account for 4% of the total recorded injuries, this is a comparison to the total number of firefighters and not relative to the proportion of female firefighters. If injuries were compared relative to the total number of female firefighters, we would suspect this to be a higher rate. This is a fair assumption considering this trend has been shown to exist in sports and among military personnel. Male or female, there are things that firefighters can do to prevent injuries. However, due to gender differences, this is especially true for our female firefighters.

Female firefighters who have played sports might know that female athletes are more susceptible to knee injuries when compared to their male counterparts. Studies show that female athletes are three to eight times more likely to tear their ACL (anterior cruciate ligament) when compared to their male counterparts (Griffin et al Am J Sport Med 2006). Studies looking at injury rates in military personnel found similar trends with female military recruits sustaining injuries at a rate double that of their male counterparts. Among these, the knee is the most frequently injured joint (Tech Bull Med 592, US Dept Def 2012).

Why is this the case?

There are several anatomical variances between females and males that are well documented in the research that contribute to increased injury rates of the knee. Some of these include the size of the ACL (which is smaller in diameter in females), the femoral notch (notch that the ACL runs through) is narrower in females adding to increased wear and tear on the ACL with pivoting movements and hormonal changes which impact the elasticity of the ligaments of the knee.

Another variance that impacts the knee has to do with the width of the female pelvis versus the male pelvis. The wider female pelvis changes the angle of the femur (upper leg bone) relative to the lower leg. This is known in the research as the Q-angle (quadriceps angle) not only impacts the strength of the muscles supporting the knee but also changes the way the knee moves upon impact (landing from a jump) and how the joint absorbs force. The force angle (represented by the red line) is more likely to drive the knee into a dynamic valgus position upon landing.

It is this dynamic valgus position that puts abnormal stress on the meniscus as well as the ligamentous structures of the knee. This dynamic valgus position is the number one risk factor for injuring the knee (Johnston et al Am J Sport Med 2018; Owusu-Akyaw et al Am J Sport Med 2018). Although these anatomical variances cannot be changed, you can assess the movement patterns that result and use that information to create training that can minimize the risk of injury (Nessler et al Cur Rev Musculoskelet Med 2017). Whether you are a female Division I soccer player, female military recruit, or a female firefighter, the movement patterns are the same and when improved, mitigate the risk for injury and decrease the severity of the injuries when they occur (Garner et al In J Kines Sport Sci 2020).

Having over a decade of this information in sports and movement data on >70,000 active individuals, we now know what weaknesses in the kinetic chain are adding to these movements and what tightness or lack of mobility in which joints is leading to altered movement patterns. The best part of all of this is that targeted training for the most common weaknesses and tightnesses/mobility issues will have a huge impact on both the number of injuries as well as the severity of injuries when they do occur.

Based on all the data and research, it is important for female firefighters to consider adding the following exercises to their routine to prevent knee injuries. Doing so will aid them in controlling whole limb stability and prevent dynamic valgus.

Targeted gluteus medius strengthening

Sidestep with theraband

With a band around the ankles and while remaining in a partial squatting position, sidestep in one direction. This exercise targets the gluteus medius but you will also get a great quadriceps workout with the partial squatting position.

Perform 15 reps in one direction and then repeat 15 reps in the other direction. This is a high-rep exercise. Start with 15 but can build up to 30 reps in each direction.

Things to watch for: Make sure to remain in the squatting position throughout the exercise and do not rise up throughout the movement. This makes it easier to do. Make sure to not allow your toes to toe out. This decreases the activity of the gluteus medius.

Single leg stance with hip abduction/external rotation in prevention of knee injuries

With a band around the knees and while standing on one leg while bending the knee of the non-stance leg. Raise the non-stance leg in the abduction and external rotation. This exercise targets the gluteus medius but is also extremely challenging to the stability of the stance leg.

Perform 10 reps on one side and then repeat 10 reps on the other. This is a high-rep exercise. Start with 10 but can build up to 20 reps in each direction.

Things to watch for: Make sure you control your stance leg. Don’t let your knee go in toward mid-line. Keep your hands on your hips to prevent from rotating your hips out. If you can only do 2-3 without losing balance, start there and build upon that.

Single leg squat in prevention of knee injuries

Standing on one leg, with the opposite limb in knee flexion and hips pointing forward, perform a partial squat 35-45 degrees without touching the opposite foot to the ground. This exercise targets whole limb stability, quad strength, and gluteus medius strength.

Perform 10 reps on one side and then repeat 10 reps on the other. This is a medium-rep exercise. Start with 10 but can build up to 15 reps on each side.

Things to watch for: Make sure you control your stance leg. Don’t let your knee go in toward mid-line. Keep your hands on your hips to prevent from rotating your hips out. Don’t let your opposite foot touch the ground. If you can only do 2-3 without losing balance, start there and build upon that.

The stability of the entire lower limb is vital to the prevention of knee injuries in female firefighters. Controlling your foot motion, knee, and hip motion is key not only to the prevention of knee injuries but also to mitigating the risk of slips, trips, and falls. Adding these three exercises will challenge your balance and stability and aid in mitigating the risk of injuries while on the job.