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Chondral Injury & Microfracture

Other popular names

Who does it affect?

Anyone, normally following a twisting or jarring injury of the knee. 

Why does it happen?

Osteochondral injury implies an injury to the joint surface or articular cartilage with some of the underlying bone.  Chondral injuries involve only the articular cartilage.

Sometimes after a jarring or twisting injury of the knee, rather than tearing a cartilage or a ligament, the articular cartilage may be damaged.  The result can be a loose fragment of articular cartilage which leaves an exposed area of bone in the knee (a crater in the otherwise smooth joint surface).  Alternatively the damage may be a breaking up or splitting, but not complete loss of, the articular cartilage in any area of the knee.

This can be a potentially serious condition, particularly in young adults, because it may give rise to long term problems. It is difficult to cure, and in the long term can increase the risk of developing significant osteoarthritis.


Normally a chondral injury will have associated pain, clicking, catching and swelling and localised to the area of trauma / injury.

If the injury has resulted in a fragment of the joint surface cartilage floating around the knee there can also be symptoms of a loose body, with clunking, catching and the feeling of something loose in the knee.


Most problems are diagnosed clinically on the basis of the knowledge of symptoms and the findings on clinical examination.

X-rays and MRI scans can help to confirm the diagnosis of the condition.

Non-surgical treatment

There are no non-surgical solutions for chondral damage.

Surgical treatment

Most acute chondral injuries will be treated with arthroscopic surgery as a day case procedure under general anaesthetic.

In general the only repairable injuries of this type are where there is quite a large chunk of articular cartilage with a sliver of bone (an osteochondral fracture) which can be pinned back in place.

If the fragment has to be removed and it leaves behind a crater in an important part of the knee with bare bone in the base, it will not heal up with normal joint surface cartilage.  It may heal up with fibrocartilage or scar tissue in the base giving some sort of smooth covering.  This type of covering can be encouraged by making some small holes in the bone.  By encouraging bleeding into the area, scar tissue will form. This technique is sometimes referred to as microfracture.

If persistent problems arise because of a defect in the articular cartilage, then there are a number of specialised techniques which may be performed, but for which not everybody is suitable.

Osteochondral autograft transplantation surgery (OATS), also called mosaicplasty, is a technique to remove healthy plugs of bone and articular cartilage from one area of the knee (where it is required less) and to put them into the damaged area.

Alternatively, Autologous chondrocyte implantation (ACI) may be a solution which involves the culture of chondral (articular cartilage) cells which have been removed from your knee and then re-implanted into the defect. 

This technique is still in development and it is not yet conclusive that outcomes are always achieved.  The technique is specialist and can only be undertaken by specialist knee surgeons

Post-surgery rehabilitation

Patients are unable to drive for six to eight weeks following surgery.

As the operation effectively creates a fracture of the tibia it requires about 3 months to heal and so the recovery time takes this long until most patients feel themselves to be ‘recovered from surgery’.

This will involve an overnight stay in hospital.  All patients will need someone to take them home and be with them on the night following surgery.
The anaesthetic will wear off after approximately 6 hours.  Simple analgesia (pain killers) usually controls the pain and should be started before the anaesthetic has worn off. 

Post-operatively, the knee is immobilised in a splint that keeps the knee straight. This is ‘weaned’ off by 6 weeks post-operatively.  No weight-bearing is allowed in the first few weeks following surgery and crutches are required for a minimum of 6 weeks and most patients are fully off crutches by 8 weeks following surgery.


The large bandage around the knee is normally removed 24-48 hours after surgery and a tubigrip to supply gentle compression to reduce post-operative swelling.

The non-stick sterile dressings on the wounds are replaced with clean waterproof dressings .

Return to normal routine

Bathing and showering

The wounds should be kept clean and dry until the wound has sealed. Showering is fine and the waterproof dressings can be changed afterwards. Bathing is best avoided until the wounds are sealed, typically 10 days after surgery.
In summary, whilst the wounds are wet - keep them dry and when the wounds are dry, you can get them wet!


Surgery is followed by a prolonged course of physiotherapy. This requires a commitment to undertake this rehabilitation in order to achieve the best possible result (at least half an hour per day for 6 months).  It is vitally important to stay within the post-operative activity restrictions an physiotherapy guidelines to avoid damaging stretching your reconstructed ligament.

Return to work

The timing of your return to work depends on the type of work and your access, however, the following is a general guide:


When you can walk without crutches or a limp and be in control of your vehicle (about 6-8 weeks).


There is significant improvement in pain ( ie reduced by approximately 80%) in approximately 90% of patients. It takes almost a year for the effect of the surgery to reach the maximal benefit.

This benefit last for more than 10 years in the majority of patients. If pain recurs, a knee replacement might be necessary.

An Osteotomy is a routine operation but no operation is without risk.

These risks include:

All these risks are uncommon and in total, the chance of you or your knee being worse off in the long term is about or less than 1%.

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