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The knee is the largest joint in the human body capable of free movement. The structure that allows for this free movement also makes it one of the least stable joints.
The knee is a synovial joint. The defining characteristic of a synovial joint is the joint cavity. This joint cavity is made up of three main features:
- The articular capsule is composed of fibrous tissue that holds together the articulating bones that intersect at the knee.
- The synovial fluid fills up the joint cavity and serves three main functions: lubricating the articulating bones to minimize friction between them, providing nourishment to the joint cells while eliminating waste products, and absorbing the shock generated by joint movement.
- The articular cartilage is a soft but firm connective tissue that covers the articulating bones to keep them from rubbing against one another.
Ligaments and tendons act as stabilizing structures for these joints. Ligaments connect bone to bone, and tendons connect muscle to bone.
Kinds of Knee Problems
The knees can be affected by the following conditions:
The unhappy triad
In the spectrum of knee problems, the “unhappy triad” is the most significant traumatic injury. It results from a strike to the side of the knee, usually during contact sports. The unhappy triad is defined by a rupture of the collateral ligament, tearing of the medial meniscus, and rupture of the anterior cruciate ligament (ACL).
Ligaments (and tendons) are known for their poor vascularity (1) – meaning they do not have an ample supply of arteries and veins. Therefore, healing from an injury to these soft tissues can take significantly longer than healing from an injury to a bone or muscle.
Patellofemoral syndrome is a condition in which the cartilage of the knee cap is irritated by contact with the cartilage of the femur. This condition can be an indicator of osteoarthritis in the future. (2)
The primary causes of patellofemoral syndrome are forcing the knee to do more work than its structure can manage and poor alignment. The knees should align over the second and third toes of the feet during most activities, and the feet should be no more than slightly outside the width of the hips and toes pointing forward for most activities.
Osteoarthritis is a condition in which the knee (and other similar types of joints) loses healthy cartilage. It can result from the cumulative effects of aging, injury, obesity, or long-term repetitive movement. (3)
Due to the loss of cartilage, the ends of unprotected bones rub together during joint movement, and this is usually very painful.
Simple Knee-Strengthening Exercises
The following are some stretches and exercises you can do to keep your knees healthy and to support the surrounding tissues in order to maintain stabilization as much as possible within the joint.
1. Calf stretch
The calf muscle is connected to the hamstrings and back of your knee. Thus, working out your calf muscle will strengthen, stabilize, and support your hamstrings and knees.
- Stand 2 steps away from a wall with your face toward it.
- Place your palms on the wall at or slightly below shoulder height.
- Move your right leg a little forward with its knee slightly bent but keeping your left leg straight and angled back.
- Push the left heel into the ground while leaning your body toward the wall such that you feel a stretch in your left calf. Step back from the wall a little more if you wish to increase the stretch. Hold this position for 10 to 20 seconds.
- Do this 3 times on each leg.
2. Adductor stretch
The adductor stretch is a lateral lunge exercise that is one of the most basic ways to work out your adductor muscles.
- Stand up straight with your feet wide apart.
- Bend your left knee and slide your hips to one side such that you feel a pull on the inside of the opposite thigh.
- Hold this pose for 1–2 seconds, or you can increase the hold time if needed.
- Return to the starting position.
3. Hamstrings stretch
The hamstrings are a set of three muscles located at the back of the thigh between the knee and the buttocks. Pulling or straining these posterior thigh muscles can make it difficult for you to move your knees, and so it’s important to protect them from such injuries by keeping them loose and agile.
- Stand with your right foot on the floor and your left foot stretched out in front with its heel grounded and toes in the air.
- Tilt your torso forward, and push back your hips while slightly bending your right knee but keeping your left leg completely straight and exerting your weight on the edge of its heel. You should feel a pull in the hamstring of the left leg.
- Hold this stretch for 30 seconds.
- Switch legs and do the same exercise.
- Perform this exercise 2 times on each leg.
4. Lateral tube walk
- Wear a resistance band around your ankles.
- Lower your body into a half-squat, keeping your core tight, engaging your glutes without letting your knees cave in, and keeping your weight in your heels.
- Move one foot sideways while pushing into your heel so that your knee doesn’t collapse under the pressure.
- Do the same with the other foot.
Note: You can wear another resistance band above your knees for additional challenge.
5. Hamstring curl
- Stand up straight with your feet placed slightly apart.
- Place your hands on your hips.
- Bend your knee backward to bring your heel as close to the hip as possible while keeping the thigh straight.
- Hold this pose for 2 seconds, and then bring your foot back on the ground.
- Do the same with the left leg to complete one repetition.
- Try 20 repetitions in one go.
6. Ball squat
- Stand with your feet shoulder-width apart and your back facing a wall.
- Hold a stability ball between your back and the wall.
- Lean back into the ball for support and move your feet a few feet away from the wall.
- Exhale and slide down your upper body along with the ball into a squatting position such that your thighs become parallel to the floor, but your knees shouldn’t move ahead of your toes.
- With an inhale, gradually push your body back up to a standing position without letting go of the ball.
- Do this entire exercise 8–10 times in one go.
- Stand up straight, keeping your feet at hip-width distance. You can choose to carry weights for this exercise.
- Put your right foot several steps forward.
- Squat down such that your right thigh becomes parallel to the ground while your left knee almost touches the ground. Make sure to keep your back and buttocks erect, because if they cave in or bend, it usually implies that you haven’t stepped out far enough or lowered your body enough.
- Stay in this position for a minute, and then return to the starting position.
- Do the same with the left leg.
- Perform 1–2 sets of 10–15 repetitions.
People over the age of 50 and those with chronic knee problems, such as arthritis, should take extra care with their knees.
These populations should continue (or begin) an exercise regimen that maintains good form and ensures good production of synovial fluid within the joint capsule to keep the joints lubricated. Always follow your doctor’s recommendations for exercise.