Knee Hyperextension is the injury that occurs when you inadvertently straighten your leg excessively at the knee joint and damage the knee structures (knee ligaments in particular) as a result. This injury can happen as a result of a sudden and forceful blow to the knee from the front. It can also occur if you stop or decelerate sharply while running. The symptoms of knee hyperextension include pain at the back of the knee (and possibly the front also) as well as knee swelling and instability. Knee ligament damage may also be a factor. Treatment usually involves rest, icing, compression and elevation but may also include surgery in severe cases.
Incidents leading to knee hyperextension tend to mainly occur while you are playing certain sports such as hockey, soccer or football. For example, if you are forced to stop sharply and do so by placing all your weight on one leg, this can push either your femur (thighbone) or patella (kneecap) over your shinbone (tibia). This can in turn force your knee into an hyperextension.
Impacts to the front of your knee, such as if you experience a tackle while playing football or soccer, can also result in hyperextension.
However, hyperextension can also happen in other non sports related incidents. For example, it may occur in a car accident in which an occupant of a front seat has his or her knee hit the steering wheel or dashboard.
Symptoms Of Knee Hyperextension
Symptoms of this injury generally include some or all of the following:
Knee instability, or a feeling that your knee cannot support your weight without “buckling” under you. One telltale sign of this is difficulty standing on one leg.
Knee pain, usually at the back of the knee but possibly in other parts also, depending on which if any ligaments suffer damage. The popliteal ligament that runs along the back of the knee is most likely to suffer damage. However, other knee ligaments such as the Anterior Cruciate Ligament or the Posterior Cruciate Ligament may also suffer tearing or ruptures due to the hyperextension.
Decreased range of motion of the knee joint as well as swelling of the joint;
Bruising of the skin around the knee.
The number of these symptoms that appears will depend on the severity of the knee hyperextension as well as on your physical condition. The weaker your knee joint in general, the more symptoms you may experience and the greater will be their severity.
The treatment of mild or moderate knee hyperextension that do not involve torn or ruptured ligaments may include:
Resting your knee by refraining for a while from activities that could repeat or aggravate the hyperextension. A hinged knee brace can be useful in providing the knee ligaments the support they need to heal properly while helping to prevent another hyperextension.
Icing your knee to reduce pain or swelling. For this, you may use either ice or a cold pack. If your pain or swelling is especially severe, your doctor can prescribe anti inflammatory medication for further relief of these conditions.
Keeping your knee elevated above heart level as much as possible while lying or sitting down.
If you have suffered severe ligament or meniscus damage (e.g. tearing or rupturing) as a result of your knee hyperextension, your doctor may advise surgery to properly correct the injury.
After surgery, your doctor will likely suggest a period of rehabilitative exercise to strengthen the knee joint and its ligaments and prepare them for a return to normal functioning. You may be referred to a physiotherapist for this part of your treatment.
How Long Will I Need To Recover From This Injury?
If your knee hyperextension injury is mild enough to require only conservative (non surgical treatment) you may be ready to return to normal activity in about 3-5 weeks.
However, if you need surgery to repair ligament or meniscus damage, recovery may take longer. Including your rehabilitation period, you may need as much as 6 months (and possibly longer ) to recover fully.