Jothy Rosenberg, Ph.D. Founder & Chairman, Dover Microsystems, Inc. Founder, The Who Says I Can't Foundation.
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Osteosarcoma is rare, yet it’s the most common form of bone cancer among children. It is an aggressive cancer, and removal of the diseased bone must be done quickly. The most common location for osteosarcoma is in the knee, and the surgical options for treatment of such an instance include limb salvage, where the diseased bone is replaced with a metal implant, a replacement bone from a cadaver, a transplanted live bone from a donor or perform an above-knee amputation. I had osteosarcoma in the femur bone in the knee and had an above-knee amputation when I was 16.
The choice of treatment among those options matters significantly to the child. Limb salvage creates a fragile leg not suitable for any type of contact sport or any sport where a fall or collision is possible. On the positive side, body image issues do not exist except when the recipient is unable to achieve a normal walking gait. An above-knee amputation means no foot, no ankle and no knee to help generate power or provide a sensation of the body’s interface to the ground. This means forever walking with a strong limp and potentially having severe body image issues, especially when not wearing a prosthesis. The positive aspect of an amputation is, with the help of appropriate adaptive equipment, being able to participate in many high-challenge sports such as skiing, biking and running.
An infrequently employed, highly advanced surgery called rotationplasty offers the best of both worlds. Rotationplasty, also known as a Van Nes rotation, is a type of limb salvage where a portion of the leg where the tumor resides (typically at the knee) is removed, while the remaining limb below the affected portion is rotated and reattached. The limb is rotated because the ankle flexes in the opposite direction as the knee. The benefit to the child is that they then have a functioning knee joint to which a prosthetic can be fitted, and this means they can be fully active and play sports that someone with an amputation, or limb salvage, cannot.
The surgery takes 8-10 hours, most of which is spent carefully resecting nerves and blood vessels that must be preserved for the foot and ankle to remain functional and healthy. To avoid having to make a huge number of potentially damage-inducing reconnections, the nerves and blood vessels are not cut. Because the nerves and blood vessels will now be much shorter than before, they are formed into a loop that is sewn inside the skin of the thigh.
Besides the significant activity advantages, retaining a sensory-motor functional foot avoids neuroma pain or phantom pain. Neuroma pain is caused by major nerves being cut, resulting in disorganized growth of those cells at the cut site, which can become painful. Phantom sensations or pain is perceived to come from where the missing body part should be. Neither of these types of pain occur after rotationplasty because a functional foot remains intact and the brain is not getting signals that confuse it. With rotationplasty, the child won’t need additional surgeries, and they won’t have an implant that wears out. It’s their own body; it heals.
After rotationplasty, the construction is durable and grows naturally with the child. The procedure is most often used for younger children (under age 12) who have a lot of growing still to do whereas other types of limb-salvage options may not work well. With rotationplasty, the bone will continue to grow with the child, and the prosthesis can be correspondingly lengthened. The foot retains proprioceptors (nerves responsible for reporting the position of joints) so the child continues to know the position of the foot and therefore of the prosthesis and thus a normal gait is restored. After rotationplasty, the rotated foot allows for active knee (aka ankle) movement of the prosthesis and full weight bearing, making all activities possible, even gymnastics.
As one might expect, retraining the brain to think of the ankle as the knee is hard but turned around 180 degrees even more so. For example, a common initial reaction, where the eyes and the sensations traveling to the brain from the nerves do not coincide, is, “My leg doesn’t feel backwards.”
To start to align these two sensory inputs, therapists touch the skin while the child observes the fingers. The key is lots of repetition of every step of retraining. Gait training starts on two crutches. Children struggle to have the strength to bend the prosthetic at first and a lot of gait training is focused on learning how to bend and straighten the prosthetic while stepping forward with crutches. The process advances to using one crutch and finally to no crutches. The process of achieving a fully normal gait takes approximately two years.
While teaching gait, establishing positive body image operates in parallel. Initially, the child doesn’t want to look at their leg post-op. Ultimately, the therapy shifts to focus on control over movement and acquisition of new skills toward independent mobility.
If medical complications such as nerve injury and skin breakdown can be avoided, rotationplasty gets amazing results. Although it looks like an amputation, it is not perceived as one because the child is weight-bearing on their natural foot. The child retains active control of the knee. It transforms what would have been an above-knee amputation into a below-knee amputation with the advantage of weight-bearing, and perception, on their normal foot. This leads to a superior quality of life compared to limb-sparing surgery or traditional amputation.
Rotationplasty remains rare because very few surgical teams are experienced at performing the procedure. It was not even offered to me when I was 16. More teams need the training. I believe that when a child gets ill with bone cancer, then all efforts should be made to find a rotationplasty team to preserve their foot and ankle and turn their situation into a below-knee amputation. This will make them much happier, fully active adults.
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