Anatomical Concepts (UK)
Masters of Rehabilitation Engineering
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Derek Jones: Anatomical Concepts (UK) Blog

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Which knee orthosis to use for severe osteoarthritis?

Osteoarthritis of the knee produces pain and reduced quality of life and orthotic bracing is commonly used as a conservative management approach. Depending on severity and choice of brace it can be helpful. The accepted wisdom is that bracing is less effective with severe osteoarthritis - but what do you use when surgery is not possible, refused or too risky?

The V-VAS orthosis is a custom fit design that is superb as a conservative brace for severe cases of osteoarthritis that would normally require surgical management. We challenged the V-VAS with a series of cases where total knee replacement surgery was indicated but not possible for a variety of reasons. The results showed high reductions in pain, increased walking distances and high levels of patient satisfaction.

Osteoarthritis is the most common form of arthritis in the knee and affects a significant percentage of the population to some degree. It is a degenerative,"wear-and-tear" type of arthritis that occurs most often in people 50 years of age and older, but may occur in younger people, too. In osteoarthritis, the cartilage in the knee joint gradually wears away and this can result in symptoms like these:-

  • Joint aching and soreness, especially with movement

  • Pain after overuse or after long periods of inactivity

  • Stiffness after periods of rest

  • Joint swelling

The knee joint in healthy, normal use has the femoral and tibial bones in contact as necessary to transmit the loads that are generated naturally by movement as we live our lives.

The gliding action of one bone on the other is made easy and pain free by the presence of cartilage, special fluids and other structures. When the cartilage becomes damaged and worn away we have an environment that produces and accelerates this wear and tear.

Knee specialists refer to the medial (the inside aspect) and lateral (the outside aspect) compartments of the knee and commonly it is the medial compartment that takes the highest share of the loading and is most often the area that is affected by osteoarthritis.

Treatment Options

As with most things medical, the treatment approach generally depends of the conditions severity. The first-line treatment of Osteoarthritis can involve a combination of weight loss if needed, medication, physical therapy with muscle strengthening exercises, hot and cold compresses to the painful joint, removal of joint fluid, injection of medications into the joint, and the use of supportive devices such as simple orthotic braces. Surgery may be helpful to relieve pain when other treatment options have not been effective.

Orthotic Products

The V-VAS knee orthosis for single compartment osteoarthritis

Many orthosis designs exist for the management of patients with osteoarthritis of the knee. Some of these are available to order “off the shelf” and some are custom made. Many off the shelf products are relatively inexpensive but will do little more than keep the joint warm or help with swelling. More advanced designs cost more but will attempt to “unload” the part of the joint surfaces in the knee.

The pain is caused because in effect as the natural cartilage becomes worn we have bone rubbing on bone and the normal smooth gliding action of the knee is compromised. If the majority of the damage is on the medial side of the knee, the logic of using an orthosis to unload the medial compartment is you will reduce the contact pressures in the joint in that area and thereby reduce the pain.

Custom or off-the-shelf unloader knee orthoses are widely used for relieving pain during weight bearing activities in patients with uni-compartmental osteoarthritis. Although these designs can be mechanically successful, patient tolerance may be low due to a higher concentration of pressures being exerted by straps or condylar pads. This is especially so with severe deformity and can limit the duration over which an orthosis can be tolerated. The fact is we can’t deny the mechanical realities of the situation.

We can’t offload the joint without, through the design, applying the load elsewhere.

V-VAS Knee Orthosis

The V-VAS design allows precise control over the amount of off-loading

At Anatomical Concepts we have a custom orthosis design (V-VAS) designed by our partners in the USA and we have successfully fitted hundreds of patients with severe osteoarthritis of the knee. Our orthotic director, William Munro along with orthopaedic surgeon, Martin Buchan, carried out a research study involving 147 patients with pain secondary to osteoarthritis.

These cases presented with severe pain. These patients normally would have been chosen for knee joint replacement surgery but this was not possible due to these reasons

  • patient’s age considered to young for replacement to be desirable

  • patient refused surgery

  • co-mobidities made surgery too risky

This V-VAS design was investigated due to its ability to fine-tune comfort levels at fitting, its light weight and relatively efficient biomechanical design.

From the 147 patients in the trial a total of 8 patients did not succeed in achieving pain relief and a total knee replacement was carried out. A further 4 patients discontinued use of the V-VAS orthosis.

The remainder showed statistically significant pain reduction (visual analogue score) and improved Oxford scores. This was represented in patients reporting significantly increased walking distances (on average 7 times their pre-bracing distance) and overall satisfaction ratings of 78%

Methodology

The Varum-Valgum adjustable stress (V-VAS™) custom knee orthosis is a concept for treating patients who present with either medial or lateral compartmental arthropathies.

Its design incorporates features intended to increase both effectiveness and compliance. Instead of using a narrow frame as seen on most designs, it uses a total contact cuff on the thigh and tibia along with an adjustable, self aligning, polycentric joint system to create four points of pressure instead of the usual three. There is no need for a condylar pad. This results in increased comfort.

The system’s self-aligning, polycentric hinge design, has a means of linearly adjusting the varum or valgum angle (depending on which compartment is affected) without causing mechanical joint binding.

Even with quite severe deformity the joints fit close to the knee without binding.

As stated above, the two main patient groups we initially selected for the V-VAS were those presenting with valgus /varus deformity of the knee in excess of 10 degrees and medically unfit for surgery (GROUP 1), or those too young to be considered for knee replacement surgery (GROUP 2).

In Group 2, bracing was seen as an earlier option than osteotomy and could be used in conjunction with pain-relieving injection therapy

Patients liked the fact that the design closely followed the profile of the knee without binding. Each patient was assessed radiographically and a custom cast made of the knee. Partial correction of deformity by the orthotist during cast taking was found to be important in minimising user discomfort. The patient’s perception of pain was used as an indicator of the optimum position during cast taking. It is likely that by demonstrating that pain relief could be achieved during casting, the patients expectations of the brace were raised.

At the fitting stage, the design of the orthotic joint was such that fine adjustments of the amount of offloading were possible. Immediate feedback on pain relief was a very positive aspect of the design. By encouraging the patient to walk up and down stairs ar the fitting stage, the orthotist was able to fine tune the brace performance without the need to remove and reapply.

Radiological assessment before and after use and the decrease in pain on movement were the primary methods of measurement of clinical effectiveness.

Results

In the study it was important that the brace was simple to apply, lightweight and neat in appearance as a high level of compliance was desirable. The aim of the bracing strategy was to reduce as much as possible the pain levels and where appropriate, increase levels of mobility.

The V-VAS was found to be an ethical and effective device in both study groups with almost all demonstrating significantly improved pain and mobility.

The V-VAS would not be optimal for mild cases of osteoarthritis as being a custom fit product it would be expensive compared with off the shelf products. As always, an assessment by a professional is highly recommended.

If you would like to know more - UK only Im afraid due to the nature of the product - please complete the brief form below.

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