Of the lower extremity joints, the knee sustains the highest percentage of injuries, particularly among physically active individuals (1). On the flip-side, leading a sedentary lifestyle is also linked to increased knee pain and a higher risk of developing conditions like osteoarthritis, as inactivity leads to muscle weakness, reduced joint mobility, and potential weight gain, all of which can strain the knees. 

My takeaway (coupled with experience gathered from fourteen years practicing as an Exercise Physiologist) – knee pain is common, and it’s best to know how to both prevent and treat it!

Believe it or not, knee pain is something that I struggled to manage for the best part of ten years during my ‘career’ as an AFL footballer. The repetitive jumping, landing and collisions that came with being a ruck-man certainly took its toll on my knees, especially my left knee. I had many frustrations along the way, trying to figure out the true source of the pain to ensure I could get through a game on the weekend.

These personal and professional experiences have given me great confidence in understanding the areas to focus on in order to build strong and robust knees.

Whilst there are numerous areas to focus attention on when rehabilitating and strengthening the knee, the focus of this blog is the relationship of the hip with the knee.

Why focus on the hip?

The hip is the most proximal link in the lower extremity kinetic chain and shares a common segment (the femur) with the knee (1). In lay terms, the the hip is connected to the knee via the thigh bone. As a ball-and-socket joint, the hip is designed to move in all planes (front to back, side to side, and rotation) and is second only to the shoulder joint in terms of capacity for movement. Due to the weight-bearing nature of the hips, we also require it to provide adequate stability, both during static (standing still) and dynamic postures (walking, running, squatting etc).

Due to this, impaired mobility and stability of the hip joint has a direct effect on the health of the knee, and if left unaddressed, will lead to affected movement patterns and the likely onset of knee pain.

Read more to learn my three reasons for why compressed and weak hips could be contributing to your knee pain.

1. Sitting for long periods is compressing your hips

One of the most debilitating habits we can regularly engage in is spending large portions of our day sitting down. Sitting in a chair for extended periods is a great way to compress the soft tissues surrounding our hip joints – this is why we ask all our patients at Restart during our initial pre-exercise screening how many hours per day they spend in a chair (whether it be working from the office/home, commuting, or relaxing in the evening).

When you stop and tally up the hours, and it can be surprising! 😳

 

 

A compressed hip is less likely move well, absorb and mitigate the loads that reverberate up from the ground, and withstand the forces of gravity constantly bearing down on us. When we look at the body as an integrated unit (see my previous blog titled Our Body’s Most Brilliant Tissue and How to Better Utilise It) we know that if one part of the body is inadequately performing its job, tension and strain will be passed on to a nearby area. The knee is often termed a ‘slave joint’, meaning it’s function is largely dependent on the movement of both the foot and ankle, and the hip. When things go awry at the ankle and the hip, the knee takes a hit.

Addressing hip immobilities and mobility asymmetries is an important component when helping someone overcome knee pain. Two common methods of appraising internal and external hip rotation are the following:

 

Does one side move less freely than the other, and does this correlate with your knee pain?

 

2. You have an imbalance in hip strength

A group of females aged between 18 and 40 with reported unilateral knee pain (meaning pain in only one knee) were assessed for hip strength (2). Strength of the Gluteus medius and maximus muscles were significantly less in the extremities of patients experiencing knee pain than the extremity without knee pain.

The below image illustrates the importance of the development and maintenance of adequate hip strength, particularly the two Gluteus muscles highlighted above.

 

 

Illustration A highlights the ideal line of force when landing on one leg, much like when walking. Importantly, you can see that the pelvis remains level, meaning the muscles surrounding the stance-leg hip and pelvis are effectively engaged.

Illustration B represents a common movement dysfunction known as Trendelenburg gait. Pelvic alignment is lost due to hip muscle weakness, particular through the muscles and soft tissues responsible for hip abduction. This means the line of force is further to the inside of the knee than preferred. In this scenario, the tensile strain on the lateral collateral ligament (LCL) and the iliotibial band (ITB) is expected to increase, as would the compressive forces in the inside compartment of the knee (1). If left unchecked, this could lead to early onset (or exacerbation of) knee osteoarthritis.

Illustration C shows a common compensation pattern for hip abductor weakness, and can appear as someone leaning over their stance leg when walking. The line of force is now to the outside of the knee (rather than the inside) to compensate for weaknesses at the hip. However, loading the knee is this position places tensile strain on the medial soft tissues of the knee, particularly the anterior cruciate ligament (ACL) and medial collateral ligament (MCL). This is a common mechanism for ACL injuries/ruptures, and a knee position to be largely avoided.

3. Lack of variety in your daily movement

The third reason why hip dysfunction could be contributing to your knee pain is due a lack of movement variety, particularly during exercise. This may contribute to both compression and lack of load tolerance throughout the tissues of your hips and pelvis.

Sure, as Exercise Physiologists we go by the mantra that ‘movement is medicine’, and that any form of physical activity is better than none. However, not all exercises are born equal, meaning some can be more ‘nutritious’ than others. Just like how we are encouraged to consume a variety of foods to ensure a well-rounded intake of macronutrients, vitamins and minerals, I like to consider movement in the same way. The idea of movement nutrition was first introduced to me by Jim Dooner of The Foot Collective, a team of health professionals that focus specifically on the health and well-being of the feet.

Whilst your workouts may include important movements such as squatting and lunging, you may be spending your entire workout in what’s called the sagittal plane.

 

 

As I mentioned above in the introduction, our hips are designed to move in all planes of motion (front to back –> sagittal plane, side to side –> frontal plane, and rotation –> transverse plane). This is the same for every joint throughout the body (some joints of course have greater capacity for movement in one plane versus the others). The knee joint for example, being a hinge joint, moves primarily in the sagittal plane, with much finer capacity for rotation in the transverse plane.

We know that our soft tissues (muscles, fascia, ligaments, tendons) benefit from movement variety. These same tissues are prone to the effects of dehydration should you fall into the trap of being in a fixed position (seated for most of the day) or repetitive movement patterns (continual sagittal plane movements eg squats with feet set shoulder width). If you’ve read my aforementioned blog on the importance of the fascial system, you will know how dehydrated tissue can lead to a cumulative injury cycle.

For optimal joint and tissue health, we need to expose our bodies to a variety of movements, positions and challenges. Does your workout include hip-focused exercises that require movement in each of the three planes? And if not, how can we expect to safely navigate activities of daily living, that require us to move effectively and responsively in all 360 degrees?

Something as simple as tweaking your foot position (staggered stance, feet rotated outwards slightly, feet rotated inwards slightly) for each set of squats can provide important movement variety. Both mobility and loading exercises in all three planes of motion provide nourishment to the tissues surrounding and throughout our hips and pelvis. Play-based activities and reactive exercises will expose our hips to a huge variety of positions, mirroring the movements we encounter in everyday life.

 

Conclusion

If you experience knee pain, adopting a holistic approach is key. Whilst their may be age-related or physiological changes within the knee itself, we know that the health of the knee is largely dependent on the health of our hips. Adopting strategies to promote mobile, stable and strong hips will have a positive flow-on effect to your knee health!

Happy training,

Luke

 

References

1. Powers C. The influence of abnormal hip mechanics on knee injury: A biomechanical perspective. J Orthopaedic & Sports Phys Ther. 2010 Feb;40(2):42-51.
2. Rowe J, Shafer L, Kelley K, West N, Dunning T, Smith R, Mattson DJ. Hip strength and knee pain in females. N Am J Sports Phys Ther. 2007 Aug;2(3):164-9. PMID: 21522212; PMCID: PMC2953297.
3. Feel SOMA (Self Osteo-Myofascial Application) handout following Level One Immersion course, October 2023. Created by Ian O’Dwyer.