One of the more difficult problems to treat in sports medicine is genu recurvatum.
Description of Genu Recurvatum
In this condition, an athlete sustains an injury and has excessive backwards motion of their knee (hyperextension of the knee). In these circumstances it can often be difficult to treat this problem and patients can have significant disability.
It is important to differentiate this problem from patients who may have had a growth plate injury when they were young and now have bony problems with recurvatum or in patients with polio or other muscle diseases where their quadriceps are so weak they have excessive hyperextension of the knee.
These injuries are most commonly caused by a blow to an extended knee with a subsequent injury to either some of the main knee structures or possibly just the structures of the posterior aspect of the knee.
Other causes of genu recurvatum include:
• A defined disorder of the connective tissue
• Laxity of the knee ligaments
• Instability of the knee joint due to ligaments and joint capsule injuries
• Irregular alignment of the femur and tibia
• A deficit in the joints
• A discrepancy in lower limb length
• Certain diseases: Cerebral Palsy, Multiple Sclerosis, Muscular Dystrophy
• Birth defect/congenital defect
Symptoms of Genu Recurvatum:
• Knee giving way into hyperextension
• Difficulty with endurance activities
• Pinching in the front of the knee
A careful evaluation must be performed to determine if there is any cruciate ligament tear, posterolateral corner injury, or a medial knee injury to include the superficial medial collateral knee and posterior oblique ligament. In some circumstances, none of these more commonly known structures may be injured and all of the injured structures are in the back of the knee.
Our anatomic and biomechanical research has discovered a tibial attachment of the oblique popliteal ligament which, when injured, can result in increased knee hyperextension.
The best way to clinically diagnose the amount of hyperextension of the knee is to measure the patient’s heel heights. If there is a normal contralateral (opposite) knee to compare to, an increase in heel height can be diagnostic for genu recurvatum.
A careful assessment of a patient’s overall knee alignment must be performed via a long leg x-ray. Their posterior tibial slope must also be calculated on a lateral knee x-ray. Patients who have a decreased posterior tibial slope tend to have more problems with knee hyperextension than those who have increased posterior tibial slopes. We have also discovered this as part of our research.
Treatment for Genu Recurvatum
If a patient does not have an associated cruciate ligament and/or collateral knee injury present, the usual treatment is to attempt a rehabilitation program to see if the patient can improve their overall quadriceps strength to compensate for the symptomatic knee hyperextension. If this does not work, then possibly a biplanar proximal tibial osteotomy, where the patient’s posterior tibial slope is increased, may be indicated. While these are extensive surgeries, they have been well documented to decrease knee hyperextension and allow patients to return to a high functioning level.
Our treatment for isolated genu recurvatum is a proximal tibial anteromedial or anterolateral osteotomy that increases the patient’s posterior tibial slope. These surgeries have been found to be very effective in decreasing a patient’s knee hyperextension and returning them to increased activities after the osteotomy heals.
Something that is most important in a patient who presents with genu recurvatum is to combine the clinical exam with above noted radiographs to devise a treatment plan. If a patient does not have any obvious collateral or cruciate ligament injury, then a closely supervised quadriceps strengthening physical therapy program may be indicated. For those patients who have already enrolled in a rehabilitation program and/or have continued problems with knee hyperextension, a brace that attempts to prevent hyperextension of the knee may be indicated. In our hands, we have found that almost all patients who have this problem may respond well for a brief period of time to a brace that limits hyperextension, but in general, still have problems and need to consider surgery.