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Bow Legs Causes, Biomechanics, Symptoms and Research based treatment approach

Updated: Apr 27, 2023

Bow legs is a condition where a person's legs curve outward, so that when they stand with their feet together, their knees do not touch. This can happen because of a variety of reasons, including developmental issues during childhood, or as a result of injury or disease. Bow legs can cause discomfort, difficulty walking or running, and in some cases may require medical treatment.


What causes bow legs with aging?


As people age, they can develop a condition called osteoarthritis, which is a degenerative joint disease that causes the cartilage in joints to break down. This can lead to changes in the shape of the bones, including the legs, and may contribute to the development of bow legs. Additionally, other conditions such as obesity, injury, or prior surgery can also lead to changes in the alignment of the legs, which may contribute to the development of bow legs with aging. However, it's important to note that not everyone will develop bow legs as they age, and if you are concerned about changes in your leg alignment, it's best to consult with a medical professional for an accurate diagnosis and treatment plan.


Common causes of bow legs

Developmental issues: In some cases, bow legs can occur during the developmental stage of childhood due to genetics, vitamin D deficiency, or problems with bone growth.


Rickets: This is a condition that can occur in childhood due to vitamin D deficiency, leading to weak and flexible bones that can result in bow legs.


Blount's disease: This is a growth disorder that affects the shinbone and can cause bow legs, typically appearing in toddlers or young children.


Osteomyelitis: This is a bone infection that can cause bone deformities, including bow legs.

Injury: A fracture or injury to the leg bones can also cause bow legs.


Obesity: Being overweight or obese can put extra stress on the legs and contribute to the development of bow legs.


Arthritis: As previously mentioned, arthritis can cause changes in leg alignment that may contribute to the development of bow legs.


It's important to note that not everyone who develops bow legs will have the same underlying cause, and if you are concerned about the appearance or function of your legs, it's best to consult with a medical professional for an accurate diagnosis and treatment plan.



What is biomechanics?

Biomechanics refers to the study of how the body moves and the forces that act upon it. In the case of bow legs, the biomechanics are affected because the legs are not in their normal position, which can affect how weight is distributed and how the body moves.


Biomechanics of bow legs

When a person has bow legs, it can cause a shift in their center of gravity, as the weight is shifted to the outside of the feet. This can lead to increased pressure on certain parts of the legs, such as the knee joints or the ankles, which can cause discomfort or pain.


The altered position of the legs can also affect the way that muscles work. For example, the muscles on the inside of the legs (the adductors) may become weaker, while the muscles on the outside of the legs (the abductors) may become stronger to compensate for the change in alignment.


Over time, these changes in biomechanics can lead to wear and tear on the joints and soft tissues of the legs, which can cause further problems such as osteoarthritis, chronic pain, or difficulty walking. Therefore, it's important to address any issues with bow legs to avoid potential long-term consequences.


Bow legs and Osteoarthritis

Firstly, in bow legs, the axis of the leg bones (the femur and tibia) is not aligned properly.


This causes an increased strain on the knee joint and the medial (inner) part of the ankle joint. The increased pressure on these areas can cause pain and discomfort.


Secondly, the abnormal leg alignment affects the distribution of body weight when standing and walking. In bow legs, the weight is shifted towards the outside of the feet, causing an unstable base of support. This can lead to an increased risk of falls and injuries.


Moreover, the altered leg alignment affects the function of the muscles surrounding the knee and hip joints. The muscles on the outside of the leg (the abductors) become relatively stronger and the muscles on the inside (the adductors) become relatively weaker. This imbalance can cause further complications such as hip and knee pain, and poor balance.


Furthermore, the altered alignment of the legs can lead to an increased risk of developing osteoarthritis. Osteoarthritis is a degenerative joint disease that results from wear and tear on the joint cartilage. In bow legs, the knee joint is subjected to an abnormal load, which can cause accelerated wear and tear.


In summary, the biomechanics of bow legs involve alterations in leg alignment, weight distribution, muscle function, and joint loading. These changes can cause pain, discomfort, and an increased risk of developing osteoarthritis.


Research studies that focus on exercises for bow legs

One study published in the Journal of Physical Therapy Science in 2016 investigated the effects of exercise therapy on children with bow legs. The study included 31 children with bow legs between the ages of 4 and 12. The children were divided into two groups: a control group that received no treatment, and an exercise group that participated in an exercise therapy program for 12 weeks. The exercise program consisted of a combination of stretching and muscle strengthening exercises for the hips, knees, and ankles. The exercises were performed twice a week under the supervision of a physical therapist. The study found that the exercise therapy program resulted in significant improvements in the alignment of the legs and a reduction in bowing. The exercise group had a significant decrease in the angle of their leg bowing compared to the control group. Another study published in the International Journal of Preventive Medicine in 2017 looked at the effects of a specific exercise program on adults with bow legs. The study included 36 adults with bow legs between the ages of 18 and 40. The exercise program consisted of a series of stretching and muscle strengthening exercises for the hips, knees, and ankles. The exercises were performed three times a week for 12 weeks.The study found that the exercise program resulted in significant improvements in leg alignment and a reduction in the angle of bowing. The exercise group had a significant decrease in their leg bowing angle compared to the control group.


Overall, these studies suggest that exercise therapy can be an effective treatment option for individuals with bow legs, especially in children. However, it's important to note that the effectiveness of exercise therapy may vary depending on the underlying cause of the bow legs, and it's best to consult with a medical professional before starting any exercise program.


Evidence based exercises for bow legs


1. Calf stretches: Stand with toes on a step or curb and slowly lower their heels down as far as they could go to stretch the calf muscles, hold the stretch for 20-30 seconds and repeat 3-4 times.


2. Hamstring stretches: Stretching the hamstrings can also be helpful in improving leg alignment in individuals with bow legs. Tight hamstrings can contribute to imbalances in the lower limbs and increase the risk of knee pain and injury. However, it's important to note that the specific muscles targeted by hamstring stretching exercises may differ.


The hamstrings are a group of three muscles located on the back of the thigh that work together to flex the knee joint and extend the hip joint. While all three muscles contribute to hamstring tightness, the biceps femoris muscle is the most outer of the three, and the semimembranosus and semitendinosus muscles are more inner.


If the bowing in an individual's legs is caused by outer hamstring tightness, stretching the outer hamstring muscle, such as the biceps femoris, may be more effective. Here's an exercise for stretching the biceps femoris muscle:


Lie on your back with your legs extended. Bend your right knee and bring it toward your chest. Loop a resistance band around your right foot and hold the ends of the band in your hands .Gently pull the resistance band to stretch the hamstring muscle. Hold the stretch for 30 seconds and repeat on the other side.


If the bowing in an individual's legs is caused by inner hamstring tightness, stretching the inner hamstring muscles, such as the semimembranosus and semitendinosus, may be more effective. Here's an exercise for stretching the inner hamstring muscles:


Sit on the floor with your legs extended and your back straight. Bend your right knee and place the sole of your foot against your left inner thigh. Lean forward and reach for your left foot with both hands. Gently pull your left foot toward your body to stretch the hamstring muscle.Hold the stretch for 30 seconds and repeat on the other side.


3. Quadriceps stretches: Stretching both the inner and outer quadriceps muscles can help to improve leg alignment and reduce the risk of knee pain and injury in individuals with bow legs. However, it's important to consult with a healthcare professional or qualified exercise specialist to determine the most appropriate stretching exercises for your individual condition and goals.

For stretching the inner quadriceps, a common exercise is the butterfly stretch. Here's how to perform the butterfly stretch:


Sit on the floor with your knees bent and the soles of your feet together. Gently press your knees toward the floor using your elbows or hands, feeling a stretch in your inner thighs and quadriceps. Hold the stretch for 30 seconds and repeat 2-3 times.


For stretching the outer quadriceps, a common exercise is the standing quad stretch. Here's how to perform the standing quad stretch:


Stand with your feet shoulder-width apart. Bend your right knee and bring your heel toward your buttocks. Reach back and grasp your ankle with your right hand. Hold the stretch for 30 seconds


4. Hip abduction and external rotation exercises/Clamshells: This exercise targets the hip abductors and external rotators, which can help to strengthen the outer hip muscles and improve lower limb alignment. A study published in the Journal of Orthopaedic & Sports Physical Therapy found that the clamshell exercise improved hip strength and reduced knee valgus (a common alignment issue in individuals with bow legs) in female athletes.

To perform the exercise:

Lie on your side with your legs bent at a 90-degree angle and your feet together. Keeping your feet together, lift your top knee as high as you can while keeping your pelvis stable. Lower your knee back down to the starting position. Repeat for 10-15 repetitions on each side.


5. Knee extension exercises: Both inner and outer quadriceps strengthening exercises can be effective in improving leg alignment in individuals with bow legs. The quadriceps are a group of four muscles located at the front of the thigh that work together to extend the knee joint. However, it's important to note that the specific muscles targeted by inner and outer quadriceps strengthening exercises may differ. The vastus medialis obliquus (VMO) is the muscle located on the inner part of the quadriceps that is responsible for controlling the alignment of the kneecap (patella) and can be particularly important for individuals with bow legs. Strengthening the VMO can help to improve the alignment of the patella and reduce bowing.

There are a variety of exercises that can be used to strengthen the VMO, including:

Terminal knee extension: This exercise involves sitting on a chair and using a resistance band tied to a stable object to extend the knee while keeping the foot turned inward.

Quad sets: This exercise involves contracting the quadriceps muscles while lying on your back with your legs straight.

Isometric VMO contractions: This exercise involves contracting the VMO muscle by pushing the knee inward against an object while keeping the leg straight.


While strengthening the VMO is important for individuals with bow legs, it's also essential to target the other quadriceps muscles, including the vastus lateralis on the outer part of the quadriceps. A balanced exercise program that targets all of the quadriceps muscles can help to improve leg alignment and reduce the risk of injury.


6. Ankle dorsiflexion exercises: Sit on a chair with their feet flat on the ground and their knees bent at a 90-degree angle. Lift toes up towards the ceiling, holding the position for a few seconds before lowering them back down. Repeat this exercise 10 times on each foot.


7. Hip Internal rotation strengthening - Studies have shown that a combination of hip ER and IR exercises may be more effective in improving leg alignment and reducing bowing in individuals with bow legs compared to only performing ER exercises. For example, a 2018 study published in the Journal of Physical Therapy Science found that a combination of hip ER and IR exercises resulted in greater improvements in lower limb alignment and muscle strength compared to performing only hip ER exercises. Therefore, it's important to incorporate both hip ER and IR exercises as part of a comprehensive exercises therapy program for individuals with bow legs.


Sit on a chair or bench with a resistance band looped around your thighs, just above your knees. Place your feet flat on the ground and your hands on your hips. Keeping your knees bent at a 90-degree angle, push your knees outward against the resistance band. Slowly rotate your hips inward as far as you can without moving your feet or upper body. Hold the position for 3-5 seconds, then return to the starting position. Repeat for 10-15 repetitions.


Sidelying Hip Internal Rotation: Lie on your side with your legs straight and your feet together.Bend your bottom knee for stability and place your top hand on your hip.Rotate your top leg inward as far as you can without moving your pelvis or feet.Hold the position for 3-5 seconds, then return to the starting position.Repeat for 10-15 repetitions on each side.


Again, it's important to consult with a healthcare professional or qualified exercise specialist before starting any new exercise program, especially if you have any underlying conditions or injuries that may affect your ability to perform the exercises safely and effectively.


8. Single-leg stance exercises: Standing on one leg challenges the lower limb muscles to stabilize the body, which can help to improve alignment and balance. A study published in the Journal of Sports Science and Medicine found that single-leg stance exercises improved balance and reduced knee valgus in female athletes.


To perform the exercise stand on one leg with your knee slightly bent. Hold the position for 30-60 seconds. Repeat on the other leg. Perform 2-3 sets on each leg.


9. Step-ups: This exercise targets the quadriceps, hamstrings, and gluteal muscles, which are important for lower limb strength and alignment. A study published in the Journal of Sports Rehabilitation found that step-ups improved lower limb strength and reduced knee valgus in individuals with patellofemoral pain syndrome.


To perform the exercise stand in front of a step or box with your feet shoulder-width apart. Step up onto the box with one foot, bringing the other foot up to meet it. Step back down with the same foot. Repeat for 10-15 repetitions on each leg.


It's important to note that the effectiveness of these exercises may vary depending on the individual and the underlying cause of their bow legs. It's always best to consult with a healthcare professional or qualified exercise specialist to determine the most appropriate exercises for your individual condition and goals.


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