Knee ligament injuries
You may have damaged your anterior cruciate ligament (ACL).
It is damaged by a severe twist with the knee straight or if forced to the side. It is
a short thick ligament in the middle of the joint. It immediately retracts, and
cannot be simply repaired. Sometimes the lower attachment to the tibia may pull
off a piece of bone and the ligament remains intact. This can happen in a young
person, and would show on an Xray. It is the only time an early operation may
be advised to fix it back.
After the injury, the knee may be swollen for some months. The ligament does
not heal.
What trouble can I expect from my knee ?
Your knee may give way on twisting movements. The bones can slide out of
place particularly when it is almost straight. If the right knee has been injured
then twisting on the knee to the right-hand side will make the knee unexpectedly
buckle. This gives a feeling of ‘giving way’ or the knee ‘dislocating’. Twisting in the
opposite direction is not so bad. If the knee is bent it does not give out so easily.
The knee can feel quite good whilst running in a straight line but suddenly give
out when trying to turn. If the knee is kept bent e.g. when skiing, there may be
less of a problem. If the knee gives out badly on occasions then it may swell
again and be uncomfortable for several weeks. Sometimes there are other
symptoms which suggest that the cartilage might be torn as well (clicking,
clonking or actually jamming up from time to time). Ligament and cartilage
damage commonly occur together.
D J Bracey Oct 2009
Ligament Information sheets
What can I do to help my knee ?
At first an unstable knee can be very worrying and people wonder if they will be
able to cope. Nevertheless as time goes by, and the pattern of instability
becomes clearer, then it is possible to avoid the movements which make the
knee give out. Trying to carry on and “learning to live with it” can lead to an
apparent improvement. The knee should be kept strong by regular exercises to
build up the muscles on the front of the thigh and in the hamstrings. Some
people feel that an elasticated support over the knee is helpful. This seems to
give more feedback from the knee though it does not actually support it. So long
as it is not too tight and is comfortable then it is reasonable to use a Tubigrip. It
should not be used if there are varicose veins or if it causes swelling of the shin or
ankle.
Is there a knee brace I can wear ?
There are several effective knee braces. They can only be worn for an hour or
two which makes them useful for sport but not to wear all day long. The knee can
feel completely stable in a brace and allows a return to some sports. Wearing a
brace actually allows the knee to strengthen up because the muscles can be
used more efficiently. They are expensive but can be supplied on the NHS or
privately. They are only recommended if the knee is still a major problem six to
twelve months after the injury. Braces can be obtained directly from the
Physiotherapy or Occupational Therapy Department
Can the ligament be repaired ?
Immediate repair is not advisable. Firstly, it is impossible to draw together the
frayed ends of the ligament to make it strong again, and operations done soon
after the injury are more likely to result in a stiff knee. It is only on rare occasions
when a piece of bone has pulled off that it can be screwed back into place. The
ligament is usually reconstructed using a graft, done at a later stage when the
knee has recovered as much as possible from the original injury. The surgeon will
use a piece of tendon or tissue from elsewhere around the knee to make a new
ligament.
What does a ligament operation comprise ?
A careful assessment is necessary before you would be advised to proceed, to
see that the instability is definitely due to loss of the cruciate ligament and to
check for tears of the cartilage. A ligament reconstruction is a major operation
keeping the person in hospital for several days. The new ligament is constructed
either from a strip of the patella tendon from the front of the knee, or by using a
hamstring tendon. The patella tendon is wide enough to allow a strip of
approximately 1cm to be taken from the middle third. This comprises a piece of
bone from the patella itself, the strip of tendon, and at its lower end, another piece
of bone from the tibia. This long strip of tissue is passed through the knee and
fixed in tunnels in the bone with screws. The operation leaves a 6” scar down the
front of the knee.
If a hamstring reconstruction is advised, part of one of the tendons near the back
of the knee is taken through two small incisions and this is passed through the
joint by a ‘keyhole’ technique.
D J Bracey Oct 2009
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Ligament Information sheets
What happens after the operation?
In both operations, the ligament is fixed with screws. Knee bending can start right
away and swelling is controlled by ice-packs. After a few days, walking is allowed
with crutches. If it is difficult to, walk a brace may be advised. Physiotherapy is
organised to encourage knee bending which should reach 90º (about half way)
within the first few weeks. This does depend on being determined enough to bend
the knee despite the pain. By 6 weeks the knee should reach 120º and at 6
months it should hopefully be full . Driving and swimming (except breast stroke)
are allowed at 6 weeks. No sport is allowed for 6 months at least and no contact
sport for a year.
Is the operation a permanent success ?
If the operation goes smoothly then the knee should be stable and have a full
range of movement. Occasionally there can be some loss of movement, such
that the knee does not come down absolutely straight and or lacks full flexion.
This might make it difficult to get down to a full squat.
As with any major operation, complications may occur. The most serious problems are caused by infection which, fortunately, is rare. This could make the knee
stiff. Sometimes, years after a ligament operation, the knee may develop wear
and tear. This may be due to damage done in the knee at the time of the original
accident. The further damage that results from the knee repeatedly giving way
may be prevented by a ligament operation.
The patella ( kneecap ) is slightly weakened by the removal of the strip of tendon
and bone and can take several months to fully recover. Until that time there is a
small risk of getting a fracture (break) of the patella if there is another accident.
There is usually a numb patch over the front of the knee around the scar.
Kneeling may be uncomfortable. The most common early problem is swelling of
the knee and bruising which may extend down the shin. This might be made
worse by blood thinners which are given to prevent thrombosis.
The long term results are good. Once the graft has healed up properly it becomes
a proper ligament but never quite as strong as the normal anterior cruciate
ligament. Occasionally healing of the new ligament is poor and about 10% may
rupture after a minor injury.
Could I return to sport after a ligament operation?
If the operation is successful and your knee is flexible with good stability, then
sport should be possible. The worry is the possibility of another injury that could
damage the new ligament. A return to contact sports must then be taken at your
own risk! For other sports the knee should be able to take a lot of stress without
any trouble but in the long term this might gradually lead to stretching of the ligament repair. If, as is often the case, there is still some slight instability of the
knee joint then you remain at increased risk of getting a torn cartilage. If so this
could be dealt with by an keyhole surgery. If your sport would require a lot of
kneeling then discomfort in the scar could be a problem. The screws used to fix
the ligament in place are well under the surface of the bone and do not need to
be removed.
D J Bracey Oct 2009
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