How to treat kneecap dislocations
The kneecap (patella) connects the muscles in the thigh to the shin bone (tibia). Some people are prone to dislocating their kneecap due to underlying problems with their anatomy. Others dislocate it traumatically when they are playing sport.
Patients typically describe a sensation of the kneecap ‘popping’ out to the outside aspect of the knee, which is associated with pain. Due to the muscle spasm that ensues, the kneecap can occasionally move back into its normal position by itself. Sometimes, a medical practitioner will need to push the kneecap back into place once the patient has been given pain relief.
Why did my kneecap dislocate?
Many factors can cause the patella to dislocate. Some of these are listed below:
A deficient medial patellofemoral ligament
The MPFL acts as a check-rein to hold the patella in the groove that it usually sits in.
A shallow trochlear groove
The kneecap sits in a V-shaped groove called the trochlea. Some people are born with a shallow trochlear groove that does not hold the kneecap in position well.
A high riding patella
Some patients have kneecaps that sit higher than normal and therefore take longer to engage in the trochlear groove. This makes it more likely to dislocate.
Problems with knee alignment
Having knock knees (valgus) can make you more likely to dislocate the patella.
Problems with the rotation of the thigh and shin bones
The way the femur and tibia bones are rotated can cause the kneecap to dislocate with less force.
Joint hypermobility
Some people have joints that can stretch beyond normal limits. This laxity or hypermobility can cause the patella to dislocate more frequently.
Emergency management
Putting the kneecap back into place
The priority in a kneecap dislocation is to get the patella sitting back where it should be. On the sports field, this manoeuvre can be performed by an experienced sports physician or physiotherapist. If there are no suitable health practitioners available, you should go to the nearest emergency department to have a doctor perform this for you.
Excluding a fracture
Depending on the circumstances, your treating medical practitioner may request an X-ray to exclude a fracture within the knee.
Aftercare
Control of swelling
Often, due to the traumatic nature of the injury, the knee becomes swollen. The swelling can take 6-8 weeks to settle down. It is essential to wear a compression bandage (e.g. Tubigrip), ice the knee, and take some anti-inflammatory medication (e.g. Voltaren or Neurofen) to help with the swelling.
Restoring range of motion and weight-bearing
In the emergency department, you may be prescribed a straight knee brace. The purpose of this is to keep the knee still and reduce knee pain. I encourage patients to remove the brace as soon as possible and not use it for more than five days.
Bracing the knee for prolonged periods can cause stiffness.
Early movement within the knee will facilitate your recovery. It is essential to know that bearing weight through the injured knee will not damage it further. Although you may need crutches to support you for 1-2 weeks, they should be discarded as soon as you are comfortable doing so.
Seeking the help of a physiotherapist
It is vital to seek the help of an experienced physiotherapist who can encourage early range of motion and strengthening exercises to decrease the chance of another patella dislocation. Strengthening the quadriceps and buttock muscles helps with the tracking of the patella, so it stays contained in the groove. For this to work effectively, the exercises must be maintained even when you are not attending your physiotherapy sessions. Taping of the kneecap can help with the tracking of the patella.
Red flags to seek a specialist opinion
Sometimes, when the kneecap dislocates, a fragment of bone and cartilage can get dislodged due to the trauma from the injury. This loose fragment can float within the knee and can restrict motion.
If you have a significant amount of swelling within the knee, new-onset clicking, or locking within the knee you should seek the help of a knee specialist that is experienced in patellofemoral disorders. A knee is locked when there is a loose fragment stuck within the joint. This affects the ability of the knee to straighten out properly.
An MRI may need to be arranged to exclude cartilage damage and assess the other structures within the knee. Surgery may need to be performed to remove or fix the dislodged fragment.
What to do if I have had more than one dislocation
If you have recurrent patella dislocations, you should seek the advice of a knee specialist to discuss reconstructive surgery. Repeated dislocations cause cartilage damage to the kneecap, which will progress to arthritis in the future. There are different procedures to keep the kneecap in place, which you can read more about here.
Summary
When the kneecap dislocates, it should be put back into position urgently.
Rest, ice, compression and anti-inflammatory medication can help with the swelling.
Avoid the prolonged use of a brace and start weight-bearing early.
Physiotherapy will help restore the range of motion and strength within the knee to decrease the chance of re-dislocation.
An early specialist assessment is required if there is significant knee swelling or a restricted range of motion.
Long term, repeated dislocations will require reconstructive surgery to stabilise the kneecap and decrease the risk of further cartilage damage.
Have you had a kneecap dislocation?
Mr Pai has trained in patellofemoral disorders and frequently treats dislocated kneecaps. He will organise the appropriate investigations to assess the cause of the instability and provide you with a treatment plan. Contact us to book an appointment.