Why we don’t prefer knee osteotomies

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Many arthritis patients are told to undergo an osteotomy: a procedure where the top of the tibia is cut in half and the angle of the bones are changed to decrease the weight forces on the knee joint. We rarely recommend it. Here’s why.

Arthritis of the knee joint usually involves loss of articular cartilage (the bearing surface) and, often, loss of meniscus cartilage (the fibrous cushion). As the bearing surface wears, the knee loses joint space and the angle changes. People most often become bowlegged, and sometimes knock-kneed, from this loss of cartilage.

An osteotomy is performed on the tibia or femur by either removing a wedge of bone or inserting a wedge. The wedge creates a new angle at the surface of the joint, shifting weight from the worn exterior to the opposite side of the knee. . The idea is that the misaligned (tilted or knocked) knee experiences increased loading forces and by shifting these forces the pain in the knee will be lessened.

This concept is much more popular in Europe than in the United States and is based on several factors: (1) The surgeon must be able to accurately measure the angles prior to surgery and remove or put in just the right amount of wedge. Too much will cause early wear and pain on the otherwise normal side, while too little will not relieve the forces. (2) The belief that a surgeon can predict new forces when, in fact, no surface inside a knee is flat. It is a complex surface with both convex and concave mixed slopes and surface angles on either side of the knee. Moving forces across a complex surface produces variable results. (3) The complication rate of osteotomy is much higher than for almost all other common knee joint surgeries. (4) Moving weight from a worn surface does not repair the worn surface. (5) The outcome of osteotomies is often rated as good to excellent for 80% of people for 5-10 years, after which partial or full knee jointing is required. These are relatively short-lived results. And joint arthroplasty is made more difficult, with a higher complication rate, if an osteotomy has already been performed.

The above points motivated The Stone Clinic to focus more on replacing the missing meniscus and repairing damaged articular cartilage using our Articular Cartilage Paste Grafting technique. The published results of this BioKnee program show 80% success at 17 years1. This means improved pain and function for 80% of people who had an arthritic knee who underwent this biological joint resurfacing. We rarely perform concurrent osteotomy and only do so in patients with severe knee joint angles greater than 7 degrees.

Patients surveyed must have some remaining joint space to qualify for biologic joint replacement. If no joint space was seen on the X-ray, they usually undergo robot-guided partial knee replacement surgery. These patients had a 98% chance of having a “forgotten knee” 3 months after surgery and were allowed to return to all sports.

Our long-term results of partial knee replacement surgery for athletes with no joint space will be published soon. To date, however, none of them have yet released their partial or even total knee replacement from sports participation.

For patients with cartilage loss and tilted knees, we believe that addressing the direct issue – loss of meniscus and articular cartilage – is usually a better first step than addressing angle changes. We live up to the adage that “bad biomechanics will destroy good biology any day of the week.” But good biology is the first step to fixing bad biomechanics.



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Disclaimer

The opinions expressed above are those of the author.



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