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Can Exercise Alone Help You Regain Full Flexion After Knee Surgery?

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Knee Flexion

Have you just had knee surgery and are you are struggling to get full range of movement back even with multiple sets of stretches throughout the day, and assistance from your physiotherapist?  According to Jonathan Webb and Andrew Davies, specialist knee consultants at Fortius Clinic, there could be other factors involved causing this problem other than not trying hard enough.  These factors can be categorised into bony structures, soft tissue structures and infection.

Bony Structures

Changes within the bony structures of the knee may cause problems after surgery including:

  • Extrinsic contractures (permanent shortening of a muscle or joint)
  • Multiple scars
  • Depression
  • Previous infection
  • Fibrosis (the formation of excess fibrous connective tissue)
  • Ossification (where cartilage becomes bone)
  • Pre-operative stiffness

There may also have been a problem during the surgery, such as a prosthesis being inserted incorrectly.

If any of these factors have caused poor flexion, the surgeon is less worried so long as you have at least 90 degrees knee flexion as it has less impact of your life.  However, if you have less than 90 degrees knee flexion at 6 weeks following the operation, they can perform a manipulation under anaesthetic, which will enable the knee to begin moving again.  After 3 months, if you have less than 100 degrees flexion, they will consider a knee arthroscopy (key hole surgery) or open surgery to resolve the issue.  After all of these procedures the surgeon will insist you continue with physiotherapy.

If you have fixed flexion, meaning you are unable to fully extend your knee, this could be caused by a technical error, which occurred in the surgery.  Physiotherapy and manipulation under anaesthetic may not improve symptoms and you will need to see your consultant.

Soft Tissue Structures

With soft tissue factors, consultants will need to differentiate between whether the stiffness is caused by intra-articulate components (within the joint) or extra-articulate components.  A common cause of knee stiffness caused by a soft tissue structure lies in the fat pad, the soft fatty tissue behind the kneecap, which is highly sensitive.

This can result in pain symptoms at the front of the knee and can restrict full extension. If this happens you may require further surgery to reset the fat pad and release the posterior capsule (ligament) of the knee.

As with bony structure factors, if you have problems with knee flexion manipulation under anaesthetic, a knee arthroscopy can assist with reducing adhesions (scar-like tissue which forms within the knee after surgery) to allow the knee to move.


The risk of infection after a total knee replacement is 1.55% for the first 2 years and this reduces to 0.46% for next 8 years. The symptoms that you may experience are unexpected or prolonged pain, fever, swelling, stiffness and increased white cell count within the blood.

If you do have an infection ensure that you do not start taking antibiotics until you have had a biopsy and blood test so your consultant can ensure it is an infection.  The infection can be managed with antibiotics, arthroscopic debridement (the removal of dead, damaged, or infected tissue via keyhole surgery), monitoring inflammation, rest, X-rays and bone scans. The consultant will choose the best procedure for your symptoms and type of infection.

Your chances of infection can be affected by your general health, cleanliness, use immunosuppressants, and whether you have diabetes, HIV, and skin lesions.  Pre-operative chlorhexidine (disinfectant) washes and pre-operative antibiotics can reduce the chances of infection.

The Importance of Exercise

Conversely, knee stiffness can also be due to how much exercise you perform between physiotherapy sessions. It is important to put in the hard work to give you knee the best recovery.  If you are struggling with knee movement after an operation, why not speak to one of our physiotherapists to work out the root of the problem?  Contact us today on 0207 884 0374 or email

Post by Zoe Birch, Head of Orthopaedic Physiotherapy at Physiocomestoyou.