Understanding Different Knee Injury Symptoms

An injury to your knee can lead to a variety of different physical issues. While some are mild in nature and easily treated, others are severely debilitating and require immediate medical care. Understanding your individual symptoms can help you determine a specific cause and appropriate treatment.

Knee Injury Symptoms

Verywell / Ellen Lindner


One of the most common symptoms you may experience in your knee is swelling. Also known as effusion, this condition occurs when there is a buildup of fluid within the joint that causes the knee to look bloated or puffy.

Swelling is one of the primary signs (along with warmth, redness, and pain) that inflammation is present and is typically classified by doctors on a 0 to 4+ scale (0 meaning swelling is absent and 4 meaning the swelling extends beyond the knee and indentations are made when you press down on the effusion with your fingers).

Because swelling is a common sign of inflammation, many different issues may be to blame. Most frequently, osteoarthritis or wear and tear in the knee joint can lead to puffiness in the morning or with activity. Injuries to the meniscus, bone, or ligaments can also be to blame. In less frequent cases, inflammation from a disease like rheumatoid arthritis or an active infection could be the cause.

Effusion is usually well managed by resting from aggravating activities, icing, elevating the leg, and using a compression stocking. If the swelling is not reduced with these conservative measures or if it is accompanied by a fever, chills, or worsening redness and pain, you should contact your healthcare provider immediately.

Unable to Bear Weight

In some situations, you may be left unable to bear weight through your knee. Often times this is the case after a ligament sprain or a tendon strain.

Because these structures add stability to the joint and prevent excessive movement, when they are damaged you may experience shifting in the knee or giving way when you try to put pressure on your leg. The severity of the issue may impact how frequently these sensations occur.

In addition, some types of fractures can also make it very painful to put pressure through your leg. Regardless of the cause, imaging (an X-Ray or MRI) is usually appropriate to determine why bearing weight is so difficult.

Grades of Ligament Sprains

Ligament sprains are classified by the following grades:

  • Grade 1: Only mild damage or stretching of the structure is present.
  • Grade 2: Sprains or strains occur after a partial tear to the ligament or tendon.
  • Grade 3: Sprains or strains involve a complete tear and usually lead to the greatest amount of difficulty.

Discomfort Walking

Several different issues can lead to discomfort in the knee as you walk. In middle and older-aged individuals, osteoarthritis or degenerative tearing in the meniscus can cause soreness in the joint when walking.

The pain may begin as you initiate your walk, improve slightly as you warm up, and worsen once again as you are on your feet for a longer period of time. Sprains and strains can also lead to discomfort, though these are typically preceded by an acute injury or trauma. Regardless of the cause, if the discomfort gets bad enough, it may even cause you to limp.

Typically, this sort of pain improves when you stop walking and get off your feet. Strengthening the muscles that surround the knee and hip can also help improve your walking endurance and decrease the discomfort you feel.

Persistent Pain

Persistent pain that lasts for more than a few days can be indicative of several different knee issues. Diffuse and achy pain throughout the knee that ebbs and flows with activity is usually due to osteoarthritis, especially in middle and older-aged individuals. If the pain is located in the front of the knee near the kneecap, patellofemoral pain syndrome may be to blame. This condition is more typical in younger individuals and can make running and jumping difficult.

If the chronic pain is located along the inside or outside the joint line of the knee, a meniscal tear or ligamentous sprain may also be the cause. Typically, however, these conditions are the result of a more acute injury. Regardless of the cause, persistent pain can usually be managed with rest, ice, compression, and elevation, known as the RICE principle. Should this not improve the pain, however, formal physical therapy or even surgery may be needed.

Popping or Clicking Sounds

Popping or clicking in the knee is a fairly common occurrence especially as you get older. This sound typically occurs while walking or when you bend or straighten the joint. While noisy knees are commonly attributed to osteoarthritis (which is sometimes the cause), this is not always true. Things like a ligament snapping over a bone, an air bubble in the joint fluid popping, muscular tightness, or even cartilage damage may also be to blame.

Regardless of the cause, popping or clicking sounds are typically not a reason for concern if it is not accompanied by pain. If the popping or clicking does lead to soreness, however, this may be treated with exercises focusing on improving knee strength and flexibility. Formal physical therapy may also be needed to address the underlying cause. In rare cases, if cartilage damage is present, surgery may be required if conservative treatments fail.


Stiffness in the knee is another fairly common symptom that can be caused by a wide array of conditions. This issue makes it difficult to bend or straighten your knee normally and can impact your ability to move around. Stiffness is frequently seen in combination with other symptoms like effusion and pain.

One of the most common causes of knee stiffness is osteoarthritis. Typically worse in the morning, this stiffness can make it difficult to get out of bed and take the first few steps as you begin the day. As you move around more, stiffness typically subsides until you sit down or rest for a longer period of time. Arthritic stiffness is also often accompanied by swelling and is usually well managed with the RICE principle. In addition, repeatedly bending your knee and straightening it in a pain-free range of motion can also improve the symptoms.

Unfortunately, more serious conditions like a meniscus or ligament tear, rheumatoid arthritis, or even an infection may also be to blame for the tightness in your knee. Should conservative management fail to improve your stiffness or if the stiffness began after a traumatic injury or surgery, one of these issues may be the cause and further medical attention should be sought.

Signs of Infection

An infection in your knee is a serious and potentially life-threatening condition if left unchecked, so it is important to be aware of the signs and symptoms which may indicate that one is present. These include:

  • Fever
  • Worsening pain
  • Redness and warmth in the leg
  • Swelling
  • Chills
  • Night sweats

If the infection occurs after surgery, drainage may also seep from the incisional area.

While many knee infections occur after an operation, this is not always the cause. Other things like osteomyelitis (an infection from elsewhere in the body that spreads to your bones) or septic arthritis (inflammation in the joint caused by a fungal or bacterial infection) may also be present.

Regardless of the cause, it is important to speak to your physician immediately if you have any of these signs. If an infection is confirmed, antibiotics may need to be started to combat the condition and in rare cases, surgical intervention may be necessary.

Nighttime Pain

It is estimated that up to 70% of people with osteoarthritis experience pain at night. This can possibly be attributed to the prior day’s activities causing inflammation to build up in your joints while you are resting in bed. Arthritic pain is usually sore and achy and may cause you difficulty getting to or staying asleep. Icing prior to bed, wearing a compression stocking to sleep, or elevating your legs while resting may all be helpful.

It is important to differentiate a dull ache from a sharper pain that wakes you up out of sleep, as this type of symptom may be indicative of a more significant issue like an infection or an injury to your cartilage, ligaments, or muscle.


Knee deformity may arise as a result of two factors: Following a significant trauma, like a motor vehicle accident, a fall from a high surface, or a sports injury; or developing changes from progressive arthritic conditions, leading to bowed legs and bone spurs that cause deformity around the joints.

In either case, your knee may actually appear to be visually deformed. Bones may appear more prominent and may even push against or break through the skin. In addition, the knee may dislocate or go “out of place,” causing it to stay at an odd angle. This is usually accompanied by significant swelling, intense pain, and difficulty moving the leg.

Traumatic injuries causing knee deformities are considered medical emergencies, especially because the body’s blood vessels and nerves are also commonly impacted. This issue is normally treated surgically and urgent medical care is warranted.

A Word From Verywell

Consistently performing stretching and strengthening exercises can help you maintain a strong and flexible leg and prevent many of the issues described above. That said, not all knee pain is completely avoidable.

While the descriptions listed can help you determine the potential cause of your knee symptoms, they are not meant to replace a doctor’s evaluation. If you are experiencing knee instability, nighttime pain, infection signs, or worsening symptoms, it is important to seek medical attention. Failure to do so can jeopardize your ability to appropriately treat your knee and return to your normal activities. 

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Tim Petrie, DPT, OCS
Tim Petrie, DPT, OCS, is a board-certified orthopedic specialist who has practiced as a physical therapist for more than a decade.