Knee injuries Wharanga ā-turi

Bones

Three bones meet at your knee joint:

• the thighbone (femur)
• the shinbone (tibia)
• the kneecap (patella).  

Cartilage

Articular cartilage

The ends of the bones and the back of the kneecap are covered with this slippery substance. It helps your knee bones glide smoothly across each other as you bend or straighten your leg.

Meniscus

There are 2 of these strong rubbery discs of cartilage. They help to cushion and stabilise your knee joint. 

Ligaments

Bones are connected to other bones by ligaments. There are 4 main ligaments in your knee. They act like strong ropes to hold the bones together and keep your knee stable.

Collateral ligaments

These are on the sides of your knee. The medial collateral ligament is on the inside of your knee. The lateral collateral ligament is on the outside. They control the side-to-side motion of your knee.

Cruciate ligaments

These are on the inside of your knee joint. They cross each other to form an 'X'. The anterior cruciate ligament (ACL) is in front and the posterior cruciate ligament at the back. The cruciate ligaments control the front and back motion of your knee.  

Tendons

Muscles are connected to bones by tendons. The quadriceps tendon connects the muscles in the front of your thigh to your kneecap. The patellar tendon runs from your kneecap to your shinbone.

There are many causes of knee injury. They often happen after:

• a sudden impact
• a fast, twisting movement
• an awkward fall.  

Injuries can happen to the soft tissues including the:

• menisci
• tendons
• ligaments
• surrounding muscles.

Injury can also include the bones.

Often, more than one of these parts of the knee may be injured.

Knee injuries can go on to cause other problems such as osteoarthritis.

Osteoarthritis (internal link)

Pain and swelling are the most common symptoms of knee injury. Depending on your injury:

• the pain may be mild or severe
• the swelling may be immediate or delayed
• the swelling may be a small or very large amount. 

It might also feel like your knee is:

• catching or locking up
• unstable, like your knee is giving way.

Immediate self care 

• If you have injured your knee, stop the activity you were doing.
• Apply first aid for soft tissue injuries.
• Keep any wounds clean, dry and covered.
• Take simple pain relief, such as paracetamol. Anti-inflammatories can also help with pain and inflammation. Take these medicines as directed and be aware of side effects.  

Soft tissue injuries and treatment (internal link)

Pain relief medicines for adults (internal link)

Seek advice

You should seek advice urgently from a healthcare provider if:

• you are in a lot of pain
• your knee is very swollen
• you cannot put weight on your knee
• you cannot straighten your leg
• you have bony deformity, like an out of place kneecap.

A physiotherapist or doctor can assess your knee injury. Often, a diagnosis can be made from your description of what happened and a physical examination.

Your healthcare provider will ask you questions like how the injury happened and what symptoms you have.

They will check your knee joint, including the soft tissues in your knee like your ligaments and menisci. They will also check your movement, strength and function. 

If you have a lot of swelling it can be difficult to properly examine your knee. You may be asked to come back when it is less swollen.

Sometimes, you might need an x-ray or MRI scan to find the exact problem. If it is likely you need surgery to fix the problem, you may be referred to an orthopaedic surgeon.

Scans and x-rays (internal link)

ACL (anterior cruciate ligament) injury (internal link)

Treatment depends on which part of your knee you have injured and how severe the injury is. 

A physiotherapist can help you recover from your injury. They can provide you with exercises and advice to help you get back to doing the things you enjoy.   

If your knee is very swollen and painful, you may be given:

• a compression stocking (a Tubigrip) to reduce swelling
• crutches to help you walk.

You may need time off work or to adapt your current work tasks while you recover.

Allied health (physiotherapy) — Healthpoint (external link)

Find a physio — Physiotherapy New Zealand (external link)