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Vastus Medialis Oblique - VMO Rehab
VMO stands for Vastus Medialis Oblique (sometimes called obliquus). This is part of the Vastus Medialis muscle which is one of the four Quadriceps muscles of the thigh.
What is VMO?
The fibres of VMO have a more oblique alignment than the other fibres of Vastus Medialis (hence the name!). It arises from the tendon of Adductor Magnus and converges to join the other Quadriceps muscles inserting via the patella tendon, to the tibial tuberosity at the top of the tibia (shin bone). The picture on the right shows the relative position of VMO, just above and to the inside of the knee cap.
Why is VMO so Important?
VMO is an active and dynamic stabiliser of the patella. In healthy, pain free individuals the fibres of VMO are active throughout the range of movement. In patients with Patello-Femoral Knee Pain (Chondromalacia Patella) the fibres contract in phases, inconsistently and fatigue easily.
The specific role of VMO is to stabilise the patella within the patella groove and to control of the 'tracking' of the patella when the knee is bent and straightened. Mis-firing and weaknesses in the VMO cause mal-tracking of the patella and subsequent damage to surrounding structures and aching pain.
How Can I Strengthen VMO?
First you must ensure that VMO is contracting properly. Long-term injuries such as Patello-femoral knee pain are a result of VMO malfunction, however some acute injuries cause the inhibition of VMO (e.g. Anterior Cruciate Ligament rupture, Patella dislocation & Meniscal tears).
To check the contraction of VMO:
- Sit with your legs out in front of you and a rolled up towel under the injured knee (the knee should be slightly bent)
- Put your fingers over the area of VMO (as shown above right)
- Push your knee down into the towel (so that your knee straightens and the foot lifts off the couch)
- You should feel a strong contraction under your fingers
If the muscle does not contract, continue to practice whilst pressing down gently on the muscle and concentrating on contracting the fibres underneath your fingers.
If the muscle does contract, you can continue with strengthening exercises:
Holding the Contraction:
- Sitting on a chair with the knees bent, palpate the VMO
- Start to slowly straighten the knee and ensure the VMO contracts
- Maintain the contraction throughout the movement as you fully straighten the knee and bend it again
- Repeat this twice daily until you can maintain a strong constant contraction 10 times in a row
Functional Exercises:
- Once you can hold the contraction as above, start to integrate this into functional movements such as lunges (shown above)
- With a split stance initially place one or two fingers on the VMO of the front leg
- Perform a lunge by bending the front knee and dropping the back knee towards the floor
- Maintain VMO contraction throughout the lunge
- Initially perform as many as you can while maintaining a strong constant contraction and gradually increase the number up to 20
- Repeat this process in step-up exercises too (although you may not always be able to reach to feel the muscle contract!)
- Try performing a squat against a wall by sliding your back down the wall until your knees are at a right angle (your shins should remain vertical)
- Place a large ball (such as a football) in between your knees and squeeze it
- This activates the Adductor muscles and because VMO arises from the tendon of Adductor Magnus, also stimulates VMO to contract
- Hold for 3 seconds and repeat 10 times, gradually increasing to 5 second holds and 20 repetitions
