Genu Recurvatum (Hyperextension of the knee): Causes, Symptoms,Treatment

What is Genu recurvatum?

Genu recurvatum is also known as “hyperextension of the knee,” “knee hyperextension,” and “back knees.” It is a deformity in which the knee bends backward, i.e., in a hyperextended position. It may be congenital or acquired.

In this deformity, excessive extension (hyperextension) occurs in the tibiofemoral joint. This deformity or condition is more common in women than in men and people with familial or genetic ligamentous laxity. The hyperextension which has occurred may be mild, moderate, or severe. The development of this genu recurvatum may cause knee pain and even lead to knee osteoarthritis.

genu recurvatum (hyperextension of the knee)

The normal active (by own) range of motion for knee extension is 0 degrees (fully straight), and passive knee extension up to 5 -10 degrees is considered normal. As 5-10 degrees of hyperextension is considered as physiological and hyperextension more than that is pathological. 

In genu recurvatum, the knee bends backward or goes into a hyperextended position, i.e., past 5-10 degrees of normal knee extended position, as you can see in the above diagram. And this places extra stress on your knees, which is not good for your knees.

Generally, that extra stress comes on the ACL as the ACL in the knee prevents hyperextension. It keeps a check on the tibia that it should not travel too far forward on your femur. But in genu recurvatum, the tibia travels too far forward on your femur, the knee goes in a hyperextended position, so there is an increased risk of getting an ACL tear.

Genu recurvatum Causes –

Quadriceps Contracture 

Quadriceps contracture is of two types congenital and post-injection contracture in infants. Generally, It has an onset from birth to 7 years.

Congenital Quadriceps Contracture – It is a rare condition where the knee will be in a hyperextended position from birth. Some features of congenital quadriceps contracture are

  • There will be a limitation of flexion.
  • Sometimes a thick band that becomes stressed during flexion of the knee might be palpated in the proximal area of the patella.
  • It is more common in females babies due to the dislocation of the patella.
  • It should be managed conservatively in the early phase of life, like in the first two months. Otherwise, it will become highly resistant to conservative treatment and will require surgery.

Post-injection contracture in infants- This disease’s main cause is repeated injections to the thigh soon after the birth. It is more common in infants, and the anterior thigh is most commonly affected.

The most affected muscles are vastus intermedius, rectus femoris, vastus lateralis, and vastus medialis is not affected because injections are not given to this muscle.

Trauma/Injury 

It is more commonly seen in soccer, football players, and jumping athletes. Because sometimes, the improper landing will put abnormal pressure on your knees. That abnormal pressure will pull your knees in a backward position resulting in inflammation, pain, and swelling.

If the Trauma/injury is severe, you may suffer a tear in an Anterior cruciate ligament,

Weakness 

In the hyperextended knee, patients mostly suffer weakness in their gluteal and quadriceps muscles. Stronger glutes may help you to get out of that hyperextended position.

Postural Issues 

Sometimes when you walk, climb upstairs, or bend forward to pick up something off the ground. Your knees are hyperextending, so that will cause pain, so do keep a check on your walking pattern.

Genu recurvatum Symptoms –

Pain 

There will be pain in the knee joint. The severity of pain depends upon how severe the injury is. For example, if you have torn your ACL, the intensity of pain will be high.

But if the injury is not severe or muscle weakness, the pain will be mild and pinchy.

Swelling 

Just after an injury, you may see immediate or delayed swelling in the surrounding areas of the knee. Depending upon the severity of the injury, it can be mild or severe.

Decreased Flexibility 

You will suffer difficulty in walking, bending, or climbing stairs just after the hyperextension injury. This will decrease your flexibility and mobility. And if the injury is severe, there may be damage to the internal structures such as ACL, PCL, And meniscus.

Genu recurvatum Treatment –

Quadriceps Contracture 

Congenital Quadriceps Contracture – Early correction by serial casting and splinting before two months of age (neonatal period) may fix the deformity without the surgery.

Post-injection contracture in infants- This disease happens due to repeated injection to the thigh soon after the birth. So Early recognition and prevention through passive exercises while a child is receiving injections is the best preventive measure.

Otherwise, if in both cases, if contracture got established, then the only option left is to go for the surgery to prevent the late changes in the femoral condyles and patella.

Thompson’s quadriceps plasty (V-Y plasty) is mostly performed.

Postural issue 

Your doctor or physical therapist will recommend you keep your knees in a slight bend position. Instead of keeping them in a hyperextended position. Initially, it will feel hard to adjust, but you’ll have to adjust to it and set a new normal for yourself.

Sometimes your doctor will apply Tape to the back of your knees. So in the future, when you tend to go in a hyperextended position. This Tape will signal you and help you to get out of that hyperextended position.

Muscle weakness 

Your doctor or physical therapist will recommend you strengthen your gluteal and quadriceps muscles if the cause is muscle weakness.

ACL/PCL Tear 

If the injury is severe and you have torn your anterior cruciate ligament or posterior cruciate ligament. Then you will have to go for the surgery because ACL doesn’t heal itself on its own. So your doctor will perform reconstructive surgery to rebuild the ligament.

But if the tear is minor, then there is no need to go for reconstructive surgery. Instead, only protective braces and physical therapy will help you to strengthen your muscles around the knee joint and restore your range of motion.

Related Article – 

Knock Knees (Genu Valgum): Causes, Symptoms, Diagnosis, Treatment

Genu Valgum (Bow Legs): Causes, Symptoms, Diagnosis, Treatment

Anterior Drawer Test of Knee: For Detecting Anterior Cruciate Ligament Tear

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