Medial Release in Severe Varus Deformity Arthroplasty Cases

Novel Medial Release in Total Knee Arthroplasty

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Severe varus knee deformity is a common problem in total knee arthroplasty. An uncorrected deformity has a bad influence on the longevity of the prosthesis. Although the common reason our revision varies from aseptic listening, to infection, to instability, based on my practice, the most common 1 in severe varus deformity is instability.

 

To prevent this instability and to obtain a cardiac coronal alignment and balancing deflection and extension gap a precise medial soft injury is essential. There is a unanimous agreement about the stepwise fashion release of the medial structures, yet there is no consensus about the order of these steps.

 

I’m going to focus on a relatively new concept in medial release. My ultimate aim is to advocate the priority of the superficial MCL release relative to the posteromedial coronary release in severe varus deformity cases.  This might be contrary to the mainstream recent literature recommendation.

Severe Varus Knee Case

varus knee medial release
Click to enlarge

To better clarify this situation, I think it would be useful to start with one of my severe varus deformity cases. She was a 78 year old woman with severe varus deformity and conspicuous lateral truss and instability, which had serious effects on the patient’s daily activities for many years leaving her almost disabled.

severe varus knee deformity xray
Click to Enlarge

The 3 joint viewer shows at 62 degree varus in the right knee, and 43 and a half in the left knee. Bone loss and significant subluxation of the tibia beneath the femur especially in the right knee is obvious. There is almost metaphysical stress fracture in the right tibia, which is relatively permanent in such severe cases.

In the lateral view what seems prominent is the huge osteophytes especially in the right knee.

More importantly the tibial anterior subluxation and friction contracture, which may have an effect in the restoration of extension gap and must be considered it inflection extension gap balancing.

Generally, patellar view is almost acceptable in severe various deformities unlike valgus knees.

 

Common Approach to Treat Varus Knee

The appropriate approaches can differ based on type of prosthesis, cemented or cementless stem, the amount of constraint, bone loss, stress fracture and patellar surfacing.

lateral view tkr xrayAs can be seen in postoperative x-ray for the right knee a semi-constrained prosthesis was used, and for the left knee only a stem was added to the tibial component for bypassing the load from the bone loss, which was augmented with screw and cement.

The lateral view was acceptable as well.

patella resurfaced xrayBoth patella was resurfaced, due to the severity of the damage.

 

Gap Balancing Varus Knee

More specifically, what matters in this severe deformity is appropriate restoration of gap balancing and alignment, which is not possible unless you have a release of superficial MCL.

In my experience, this release is the key in severe or even fixed moderate varus deformity.

Therefore, in these cases we can directly conduct superficial MCL release and avoid posteromedial release, which I assume to be unnecessary.

Therefore, in these cases we can directly conduct superficial MCL release and avoid posteromedial release, which I assume to be unnecessary.

Although this approach seems to be contrary to the recent literature recommendation as a new concept it can offer two major benefits.

Benefits of Avoiding Posteromedial Release

Although avoiding posteromedial release seems to be contrary to the recent literature recommendation as a new concept, it can offer two major benefits:

First, you can avoid medial under-release and therefore ensuring good alignment and stability.

This is particularly important as these days, along with development of implant designs, materials, and surgical technique, instability is the major cause of failure according to some recent research.

It’s important to note that ligament imbalance could be the underlying cause of wear, osteolysis and loosening.

Second, you can also keep vital posteromedial elements intact, which will greatly help reach faster post-op rehabilitation. The structures which are in the posteromedial corner of the knee, also have a very important role in stability, functional anatomy, and biomechanics of the knee. Therefore, it is wiser to avoid posteromedial release as much as possible and have a lower threshold for superficial MCL release in fixed varus deformity cases.

Apart from the advantages, in this approach there is no need to worry about medial over release, as long as it is performed appropriately. As Dr. Norman Scott (Dr. Scott Bio), a pioneering surgeon in total knee arthroplasty recommends, superficial empty release as a safe and effective procedure. Stressing that the superficial MCL will heal back to the bone in the new position.

Dr. Scott quote:

“I think it’s important to remember as you see us taking this stripping this off from the bone we now have probably 30 to 40 years of experience. These heal back to the bone in the new position that the arthroplasty puts them into. So, it’s extremely rare, there are very few reports of a release going on to not healing. Usually in those cases the ligament structures are transected, rather than released from the bone.”

Also, don’t worry about medial gap widening flexion because it only happens due to the posterior gliding of the medial structures. Particularly when superficial MCL release is done after releasing the posterior medial corner. Furthermore, it will disappear after capsular closure.

gap balancing superficial mcl releaseWithout superficial MCL release it is impossible to balance the gaps in severe fixed various cases like this. The other releases could mostly be ineffective and unnecessary.

The Results

Check the video above at the 7:50 mark to see the result of superficial MCL release in one of my cases. You will see this straightforward medial release can correct varus deformity to an optimum extent without the risk of over release.

Avoid medial under release, as a common cause of instability and revision in this case. Keep the vital posterior medial elements intact, which in my assumption, releasing it most of the time doesn’t have an effective influence in the balancing.

The only thing that should be kept in mind is in this release in severe fixed various cases, perform the proximal tibial cut as thin as possible.