A sprained knee is an injury due to overextension, tearing or rupturing of the ligaments in the knee. This is a common traumatic type of injury that can result from the application of a sudden force to the knee (e.g. a tackle in rugby or football) or a fall that causes the knee to twist in an awkward fashion. Typical symptoms of a sprained knee are pain, tenderness, swelling ,bruising and stiffness in the knee area. Treatment of mild or moderate knee sprains usually involves protecting and resting the knee, as well as icing, compression and knee elevation. Doctors may also prescribe over the counter pain relief medication if the pain is especially severe. A severe sprain that involves rupturing of the ligaments may require surgical correction.
As with many other types of sprain, the degree of severity of a knee sprain can be classified as one of grades I, II or III:
A grade I sprain overstretches the ligament and results in microscopic tearing only;
Grade II sprains involve partial tearing of a knee ligament and can cause moderate joint instability;
A grade III sprain involves complete rupturing of a ligament or separation from the bone to which it attaches at one end, resulting in joint instability..
Causes Of A Sprained Knee
The knee has four major ligaments – the anterior and posterior cruciate ligaments (ACL & PCL) and the medial and lateral collateral ligaments (MCL & LCL).
The function of the ACL & PCL is to stabilize the knee against front to back or back to front forces or blows. ACL and PCL sprains are usually due to blows or forces to the front or back of the knee such as a sudden stop or knee hyperextension. ACL sprains can also be the result of impacts to the outside of the knee, as well as sudden twisting of the knee while it is still slightly bent.
The MCL & LCL protect the knee against left to right or right to left forces or blows. As a result, MCL sprains can be caused by sideways blows to the outer knee or by a fall that causes the lower leg to twist outward relative to the upper leg. LCL sprains are relatively uncommon because they are usually caused by blows or forces exerted on the inside of the knee and that side of the knee is usually protected by the opposing knee.
The forces or blows that lead to a sprained knee typically occur during contact sports such as football, basketball & rugby. They are also common in sports such as skiing or gymnastics in which bodily pivoting or twisting of the joint are common.
Another event that may cause a PCL sprain is a motor vehicle collision in which a front seat occupant hits his or her knee on the dashboard.
Symptoms of a sprained knee typically include the following:
A popping sound or sensation inside the knee at the time the injury occurs. This is more typically the case with ACL sprains;
Knee pain that is particularly severe for an ACL sprain;
Knee swelling that appears within a variable time after the occurrence of the injury. This could be several hours in the case of minor sprains, whereas in completely torn ligaments the swelling usually develops within two hours.. Again, this swelling is usually more severe in cases of an ACL sprain;
An ACL sprain is also more likely to cause knee instability. This is akin to a feeling that the knee is “giving way” and cannot support the full body weight;
Skin discoloration in the region of the knee. Once again, this is particularly common in cases of an ACL sprain.
Treatment Of A Sprained Knee
Treating a knee sprain that falls into the grade I or II categories usually involves applying the P.R.I.C.E. approach within 48-72 hours of injury :
Protect the injured knee from further injury, for example by wearing a suitable knee brace;
Resting the knee by refraining (for a period) from activities that may stress the joint and the ligaments responsible for its support. For example, doctors may suggest suspending running, jumping or other sports related activity for a period. The more severe the ligament damage, the longer the period of “rest”. In addition, using a hinged knee brace or a knee stabilizer will help to protect the ligaments and help them to heal more quickly. For even greater rest for your knee, the patient may consider using crutches or a cane. These will help to keep the full body weight from being borne by the knee while walking.
Applying Ice or a cold pack to your knee for control of pain and inflammation. You may also be asked to consider an over the counter pain relief medication such as aspirin if the pain of your sprained knee is severe;
Applying Compression to your knee to improve blood circulation and accelerate healing. Wearing a knee sleeve or tensor bandage over the joint will help to achieve this;
Keeping your knee Elevated above heart level whenever possible, such as when sitting or lying down.
Things To Avoid
It is also advisable to avoid HARM for 72 hours after the injury:
Heat – for example hot baths, saunas and heat packs. Heat has the opposite effect to blood flow and encourages blood flow;
Alcohol – can increase bleeding and swelling and decrease healing;
Running – together with other forms of exercise which may cause further damage
Massage – may increase bleeding and swelling. However, as with heat, after 72 hours gentle massage may be soothing.
Medication To Use
This can include:
Paracetamol or topical NSAIDs like ibuprofen gel;
An oral NSAID like ibuprofen may be used;
The short-term use of codeine phosphate in addition to the above may be considered (drowsiness and constipation are possible side-effects)
Once healing of the knee sprain injury has progressed sufficiently, the patient should begin to work with a physiotherapist to rehabilitate the knee. This process will help to strengthen the muscles around the knee and its supporting ligaments as you prepare to resume normal use of the joint.
What To Do If Things Do Not Improve
The patient should get a medical opinion after 5-7 days if there is:
Lack of expected improvement (for example if they have difficulty walking or weight-bearing)
Worsening symptoms (such as increased pain and swelling)
If the knee sprain falls into the grade III category, the conservative P.R.I.C.E. approach may not be sufficient. In this case, surgery may be necessary to repair the torn ligament. To do this, surgeons may use a piece of healthy ligament from the patient’s knee (or a piece of ligament from a donor) to reconstruct the damaged ligament. This type of surgery usually utilizes knee arthroscopy in which the surgeon uses a tiny camera to guide the instruments he or she is using. The surgical approach is most common in cases of ACL or PCL sprains, which tend to be the most severe knee sprain injuries.