The Knee

The knee is connected and influenced by the joints above and below it – the foot, ankle and hip. Knee injuries can often be a result of tension/weakness/injury in one of these surrounding joints.

The knee is a vulnerable joint. Good knees need to be strong (as a lot of body weight passes through it) and flexible (to deal with the movements of foot and ankle).

Anatomy

• Four bones come together at the Knee: Femur, Tibia, Fibula and Patella (kneecap).

• Between and around the connection with the Femur and the Tibia are the meniscus. These are the ligaments that help support movement and stability around this joint.

The Patella (Kneecap)

• The patello-femoral joint is where the patella meets the femur.

• The patella aligns the movement at the knee. It keeps flexion and extension as true to straight as possible and is also designed for leverage.

• It is essential to the strength we have when we extend the knee. Without this bone the tendon would rub on the bones as we move the knee joint, eventually it would fray and tear from friction.

• The underside of the patella has cartilage which allows it to slide on the groove of the femur.

• The patella is held in place by the thick patella ligament (patella tendon). This ligament doesn’t allow very much movement up or down the patella once it becomes taut. Instead, as the knee bends in flexion, the femur slides under the patella. This helps keep the movement as straight as possible.

Movement:

• Flexion (bending)

• Extension (straightening)

• Rotation (when bent only)

Flexion and extension allows us to propel ourselves forward when walking or running.

Ligaments:

1. Medial Collateral Ligament (MCL) – Connects the femur to the tibia. Located on the outside of the knee on the inner part of the leg.

2. Lateral Collateral Ligament (LCL) - Connects the femur to the fibula. Located on the outside of the knee on the outer part of the leg.

The collateral ligaments prevent side to side movements and external rotation of the knee.

3. Anterior Cruciate Ligament (ACL) – Crosses with the PCL, inside the knee. More likely to get injured/torn than that PCL.

4. Posterior Cruciate Ligament (PCL) – Crosses with the ACL, inside the knee. It crosses at the back part of the tibia.

These ligaments stabilise the knee joint.

Ligament Tears:

• Grade 1 – Most common. Some pain, no heat or swelling.

• Grade 2 – More painful, heat and swelling.

• Grade 3 – complete tear (pain, heat, instant swelling)

Grade 1 or 2 tears happen when the coils of protein have been pulled apart so far that they cannot re-coil to their normal position. This results in less stability for the knee.

Meniscus

The menisci are two semi-circle pieces of additional cartilage sitting on the tibia.

They get squashed and move a bit when the knee moves. They have raised areas that allow the knobbly end of the femur to meet with the flat tibia so this makes the join more stable. They also work as shock absorbers.

• Medial Meniscus – inside of the knee

• Lateral Meniscus – outside of the knee

Meniscus injuries:

• Can tear from compression or movement.

• Tears on the outside tend to heal themselves but if torn on the inside it is more difficult to heal due to no blood supply in this area

• Over time small tears can get larger. Left untreated further problems can develop such as uneven wearing of the cartilage which can lead to arthritis.

Muscles around the knee

• Quadriceps

1. Vastus Lateralis (on the outside)

2. Vastus Medialis (on the inside)

3. Vastus Intermedius (in the middle)

4. Rectus Femoris (on top) – crosses the knee (for extension) and the hip (for flexion).

• Hamstrings – 3 muscles cross the knee and the hip joints and do the opposite of the quadriceps. They flex the knee and extend the hip joint. They also rotate the tibia when the knee is flexed.

• Iliotibial Band (ITB)

• This is a piece of fascia on the outer part of the thigh.

• It attaches the Ilium (pelvis) to the Tibia.

• Stabilises the knee when walking

• Too tight = pain in the knee

• Too loose = instability (e.g. whilst running).

• Gastrocnemius (calf muscle)

Hyperextended Knees

This can be genetic or from injury and occurs when the knee pushes back past a usual range of motion.

The bones require less muscular effort to hold in this position so there is less support around the joint.

It is therefore advisable to hold a small bend in the knee when in standing yoga postures that require the leg to be straight. This encourages the muscles work to protect the knee joint and less strain on the knee.

Yoga Guidance:

To prevent developing issues in the knees from yoga it is important to ensure the alignment of the knees is correct and you need to provide appropriate support for the knees through engaging the important surrounding muscles.

• Standing poses with bent knees (e.g. lunges, warrior 1, warrior 2) – The knee should be placed directly over the ankle. Overshooting the knee over the ankle can create a compressive force on the patella.

• Standing poses with straight legs (e.g. Triangle) – Micro-bend the knee. Keep the muscles active to avoid pressure on the patellar tendon. Pressing through the ball of the foot activates the muscles in the leg and keeps the hips in line.

• Pulling on the feet from behind (e.g. Bow, Dancer pose) – Activate the thigh muscles and push the feet into the hands. This allows strength and support to the joint and lengthens the muscles.

• Sitting poses impacting the knees (e.g. Hero, Pigeon) – these postures shouldn’t hurt so seek advice from your yoga teacher if you feel pain in the knees. The discomfort may be prevented through support from use of a block but if not the pose should be avoided.

Caution:

• If you are having any issues with your knees, it is advisable to see your doctor so that they can diagnose you and advise on the appropriate treatment.

• If you are thinking of starting yoga and have a medical condition, it is advisable to check with your doctor.

• If you are practicing yoga with any knee problems, always let the teacher know so that they can advise you on how to modify your practice. Remain mindful of the problem area and do not push yourself with anything that doesn’t feel right or feels painful.

• If you are new to yoga it is advisable to practice under the guidance of a qualified teacher so they can help advise and correct alignment.