Minimally Invasive Approach To Treat Unicompartmental Arthritis

Minimally Invasive Approach To Treat Unicompartmental Arthritis

Unicompartmental knee replacement is a very successful procedure for young patients with arthritis, because the disease is confined to the medial compartment of the knee. An added advantage of this procedure is that the knee can still be converted to a full replacement, if for any reason a revision surgery is envisaged.

The polyethylene articular insert is mobile and hence allowed to freely float on top of the tibial base, which absorbs sheer stress and protects the bone interface. As it is mobile, the design can be customized conforming to the curve of the femur bone to spread the weight-bearing capacity evenly, thereby reducing its wear and stress.

What Is Unicompartmental Arthritis?

A knee joint is divided into three compartments – medial (inside), lateral (outside) and the patellofemoral (kneecap joint). When any one of the three compartments of the knee is affected, it is referred to as unicompartmental arthritis. In most cases, only the medial or lateral compartment is affected, unlike arthritis, where it affects all the three. If diagnosed early, it can be treated with medications. However, when the symptoms have crossed the extreme stage, surgery is the only option left.

Full knee replacement has been the most common and the conventional method for treating an arthritic knee. This is useful and necessary only when all the three compartments are involved. However, it can prove to be a disadvantage in case of unicompartmental arthritis. Therefore, this is where unicompartmental knee surgeries are helpful.

In extreme cases, the pain is so elevated, that it requires immediate surgery. This is when all the three compartments of the knee are involved. Full knee replacement surgery, is the most common and conventional method and it has become the ‘gold standard’ operative procedure for treating an arthritic knee. But when the problem is limited to just one of the knee compartments, there are options to only replace these.


Orthopaedic surgeons and sports medicine specialists perform a physical examination along with the help of imaging techniques like x-rays as this helps in evaluating the degree of deformation and the alignment of the knee. It is also helpful to identify the uneven load distribution across the joint. The details of each compartment are obtained through any imaging technique which can identify issues like joint space narrowing, bone spur formation, and increased density of the bone adjacent to the overloaded compartment. However, a history of pain, limited to the medial compartment with swelling in the joint and stiffness is indicative enough to visit the doctor.

Treatment Options

The surgeon makes the decision of whether to opt for surgical treatment or to continue with medication, depending upon the age, degree of symptoms, history of other diseases and the patient’s activity level.

Non-Surgical Methods

Corticosteroid injections decreases the inflammation and relieves associated pain. The effect of these injections last up to six months and these injections contain natural components of the joint fluid that helps to lubricate and absorb shock to protect the damaged cartilage.

These are known as off loader braces which helps in correcting the malalignment of the knee and distribute the weight evenly across the joint.

As this surgery follows a minimal incision approach, a faster recovery, rehabilitation and quick return to full-fledged activities is seen in all patients

Surgical Methods

Articular Cartilage Restoration Procedures
Surgical procedures are required to restore the articular cartilage as it does not heal on its own.

A wedge of bone is cut out from either tibia or femur to adjust the angulation to straighten the knee. This relieves the uneven distribution of the weight across the joint and prevents progression.

Total Knee Replacement
This involves all the three compartments. The surgeon removes the damaged cartilage from the femur and tibia and replaces it with metal and plastic.

Unicompartmental Knee Replacement
Unlike the total knee replacement surgery, this procedure is minimally invasive and replaces only the damaged portion of the joint.

Why Unicompartmental Knee Replacements?

The main advantage of the unicompartmental knee replacement surgery is that it preserves the ACL which is a crucial ligament for movement and the knee stability, unlike in the case of total knee replacement surgery, where it is sacrificed. As this surgery follows a minimal incision approach, a faster recovery, rehabilitation and quick return to full-fledged activities is seen in all patients. Moreover, in case of unproductive results, this can also be revised to a total knee replacement procedure without any complications or additional balancing operations.

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