Knee Injury: Types, Symptoms and Treatment

First aid for a knee injury

For the first 48 to 72 hours:

1. Protect: stop the activity. Use crutches if walking is painful.
2. Rest: avoid activities that cause pain, but gently bend and straighten the knee a few times a day to prevent stiffness.
3. Ice: apply a cold pack wrapped in a cloth for 15 to 20 minutes every 2 to 3 hours while awake. Never apply ice directly to skin.
4. Compress: a light elastic bandage or sleeve can limit swelling. Loosen it if your foot tingles or turns pale.
5. Elevate: raise the leg above the level of your heart when sitting or lying.

Pain relief: acetaminophen (paracetamol) or ibuprofen, following the label dose. Avoid NSAIDs if you have stomach ulcers, kidney problems or take blood thinners.

Types of knee injuries

Ligament sprains and tears

Ligaments are strong bands that hold the knee stable. Sprains are graded:

• Grade 1: stretched with tiny tears; the knee is stable.
• Grade 2: partially torn; some looseness.
• Grade 3: completely torn; the knee is unstable.

The ACL (anterior cruciate ligament) is commonly injured in soccer, basketball, skiing and netball. About half of ACL tears come with a meniscus tear. The MCL (medial collateral ligament) on the inner knee usually heals without surgery.

Meniscus tears

The two menisci are C-shaped cartilage cushions. Young people tear them twisting during sport. In people over 40, worn cartilage can tear with a minor twist or squat. Swelling builds over a day or so, and the knee may catch, click or lock.

Kneecap problems

Kneecap (patellar) dislocation is most common in teenagers, especially girls, and people with loose ligaments. The kneecap usually pops back in when the leg is straightened but often damages cartilage.

Symptoms that suggest a serious knee injury

• A pop at the time of injury: ACL tear or kneecap dislocation.
• Swelling within 2 hours: bleeding into the joint (hemarthrosis), most often an ACL tear, kneecap dislocation or fracture.
• Swelling over 12 to 24 hours: more typical of a meniscus tear.
• Giving way: ligament instability.
• Locking: a torn piece of meniscus or a loose body blocking movement.
• Unable to straighten the leg against gravity: tendon rupture.
• Unable to walk: fracture or major ligament injury.

Do I need an X-ray? The Ottawa knee rules

Doctors use the Ottawa knee rules to decide whether an X-ray is needed after an injury. An X-ray is recommended if any of these apply:

• age 55 or older
• tenderness at the head of the fibula (bony bump on the outer side below the knee)
• tenderness only on the kneecap
• unable to bend the knee to 90 degrees
• unable to take 4 steps (two on each leg) both right after the injury and when examined

Most ligament and meniscus injuries do not show on X-ray. An MRI is the best test for these and is usually arranged if instability, locking or persistent symptoms suggest a tear.

How knee injuries are diagnosed

A clinician will ask how the injury happened, whether you heard a pop, how quickly it swelled and whether you could keep playing. They will check swelling, tenderness, movement and specific tests for each ligament and the meniscus, such as the Lachman test for the ACL. Draining blood from a tense, swollen knee both relieves pain and helps diagnosis.

Treatment

Minor injuries

Most sprains, bruises and many meniscus tears in older adults improve with first aid followed by a graded exercise program over 2 to 6 weeks.

Physical therapy

Physical therapy is central for nearly all knee injuries. It restores movement, rebuilds the quadriceps and hamstrings, and retrains balance and landing technique. A brace may be used for MCL injuries or after a kneecap dislocation.

Surgery

• ACL reconstruction for active people who want to return to pivoting sports or have ongoing instability.
• Meniscus repair or trimming for tears that cause locking or do not settle. Repair is preferred in younger people.
• Fixation of displaced fractures and repair of ruptured tendons, usually within days to weeks.
• Kneecap stabilization after repeated dislocations.

Recovery times

Long-term complications

Untreated instability can damage the meniscus and cartilage. Knee injuries, especially ACL and meniscus tears, raise the risk of osteoarthritis of the knee years later. Completing rehabilitation reduces repeat injuries.

Preventing knee injuries

• Strengthen the thighs, hips and core.
• Train safe landing and cutting technique; programs such as FIFA 11+ cut ACL injuries in athletes.
• Warm up properly and wear suitable footwear.
• Wear knee pads for kneeling work and contact sports.

Frequently asked questions

How do I know if my knee injury is serious?

Warning signs include a pop at the time of injury, swelling within a few hours, the knee giving way, locking, inability to straighten the leg, or being unable to take 4 steps. Any obvious deformity or a numb, cold foot is an emergency. These need prompt medical assessment.

Should I walk on an injured knee?

Walk as much as pain allows if you can bear weight comfortably, as gentle movement prevents stiffness. If you cannot take 4 steps, the knee gives way or it is very swollen, use crutches and get it checked, because a fracture or major ligament tear is possible.

How long does a twisted knee take to heal?

A mild twist or sprain usually settles in 1 to 3 weeks. Moderate ligament sprains take 3 to 6 weeks. Meniscus tears and kneecap dislocations often take 6 to 12 weeks with physical therapy, and ACL reconstruction needs 9 to 12 months before returning to pivoting sports.

Should I use ice or heat on a knee injury?

Use ice for the first 48 to 72 hours to reduce pain and swelling, 15 to 20 minutes at a time, wrapped in a cloth. After swelling settles, heat can relax stiff muscles before exercise. Avoid heat on a freshly swollen knee.

Can a torn knee ligament heal without surgery?

Many can. MCL tears usually heal with a brace and physical therapy. Some people with ACL tears who do not play pivoting sports manage well with rehabilitation alone. Complete ACL tears in athletes, or knees that keep giving way, usually need reconstruction.