Malalignment
Varus / Valgus / Slope Deformities
Phone +971-2-4446600
Anatomy
I think we can all agree a leg works best if it’s straight. But all of us do not have straight legs. The most common variations of this are “knocked knees” or valgus malalignment and “bow legged” or varus malalignment. There are also more uncommon, rotational, forms of malalignment.
Having valgus or varus malalignment causes increased load on one side of the knee and actually decreased load on the other side. This can result in faster wear and tear on one side or even injuries on that side due to overload. A knee with a meniscus or cartilage injury or recurrent pain without significant trauma needs to be assessed for alignment, because if there is malalignment, these injuries can have difficulty healing if the loading is constantly too high.
Another form of malalignment is when the top of the lower leg, tibia, has an increased backwards tilt (posterior tibial slope). This has been gaining more and more interest over the last decade as it has been recognized to be a risk factor for failed ACL reconstruction. With increased posterior tibial slope, the forces on the ACL are increased and that can lead to tears and instability.
Evaluation
Just watching a patient stand or walk can show malalignment. The standard assessment is to have X-rays of the full legs and then it is easy to measure if the leg is straight or if there is valgus or varus angle. Variations withing a few degrees are considered normal and very rarely needs specific treatment.
A sideways X-ray can evaluate the posterior tibial slope in the setting of an ACL injury.
To evaluate and quantify rotational malalignment, a CT-scan is needed if symptoms are present.
Normal Anterior tibial translation and posterior tibial slope
Severely increased anterior tibial translation and posterior tibial slope
Treatment
Without symptoms, even major malalignment is not treated. It is just part of how you are built.
However, having malalignment put you at higher risk of injuries and pain, and once you have an injury or start developing pain, treatment can be needed.
With medial pain or injury and varus malalignment, the overload has taken its toll and it might be time to address the malalignment. The same goes for lateral pain or injury and valgus malalignment.
Sometimes before opting for surgery, a brace can be tried that pressures the knee in correction, simulating the planned effect of the surgery. If this reduces the pain, we know that the surgical correction most likely will have similar pain relief and is well indicated.
The surgery to correct alignment is osteotomy, that is changing of the shape of the bone.
With opening or closing wedges either in tibia (shinbone) or femur (thighbone) you can straighten the knee and have the load of your bodyweight go in the center of the knee, thereby offloading the area of the pain or injury.
For the increased posterior tibial slope, an anterior closing wedge osteotomy is performed, thereby lowering the front aspect of the tibia creating a flatter top of the tibia for the femur to put its weight on. This reduces the stress forces of the ACL.
An osteotomy is done with open surgery to be able to see the bone and appropriately protect all important structures while opening or closing the wedge. The osteotomy is commonly fixed with a plate.
Varus deformity
before and after correction osteotomy
Valgus deformity
before and after correction osteotomy
Increased posterior tibial slope
before and after correction osteotomy
Rehabilitation
After an osteotomy surgery the bone needs time to heal, which will take about 6-12 weeks. However, the plate is a strong fixation and therefor you can usually start putting some weight on the leg after a few weeks and then increase week by week. It usually takes 6-12 weeks before you can let go of the crutches and walk more normally.
Physiotherapy is crucial after these surgeries as they are commonly combined with other surgeries like meniscus repairs, cartilage procedures or ligament reconstructions. The physiotherapy program starts the day after surgery aiming at getting your muscles activated and start motion of the knee. The total recovery period for an osteotomy is usually around 6 months, but with other surgeries done at the same time, this can extend up to a year.