He is an eight year-old boy.  Danny Davidson (not his real name) is running around at school and bumps his knee.  It hurts then, but he continues to play.  It still hurts after two days, so his aunt takes him to the doctor.

Danny lives on an Indian Reservation in the Midwest.  He is taken to see the Indian Health Services doctor, who examines him and performs X-rays of his knee.   The X-ray shows subtle changes in the bone around the knee, in the end part of the femur (thigh) bone.  Suspicious.

Three days later, Danny and his aunt are in our office at Mayo.  I am a second-year resident and am on a three-month rotation with Dr. Tom Shives, a Professor if Orthopedic Surgery and a specialist in orthopedic tumors.  Danny's leg is swollen around the knee.  It hurts when I bend his knee.  We perform more xrays , an MRI and a CT scan of the lungs. 

Danny is afraid of the MRI machine.  Many people cannot tolerate the scan, since the patient must lie perfectly still in a narrow, coffin-like tube for more than 30 minutes.  Danny and I discuss this, and wonder what would happen if someone could not fit into the tube.  We talk about how there are bigger machines and tubes used for large animals, like elephants at the Zoo, and that the Zoo might let larger people use their machines.  So Danny decides that so long as he does not smell elephant in the MRI machine, he is going to lie still and make the most of it!

Danny has telangiectatic osteosarcoma, a rare bone cancer which is very aggressive.  The cancer has spread to two spots in his lung.

Years ago, the prognosis for this tumor in the presence of metastatic disease was grave.  Now, chemotherapy as an adjuvant to surgery increases survival to about 65% at five years.   Danny will undergo two rounds of chemotherapy, followed by re-staging and then surgical removal of the tumor.  After surgery, he will receive two more rounds of chemotherapy.

In addition to all of this, Danny is not able to live with his parents.  His mother and father are not married.  His father lives with another woman at the same reservation.  His mother has six children, with three different men.  She is having trouble with her bills;  no hot water, no phone service.  She is unable to care for Danny and his siblings.  So he will stay at Mayo alone for most of his treatment.

Over the course of his chemotherapy, Danny and I become friends.  I learn of his love of basketball and action movies.  I learn that he likes the shakes at McDonalds.  We continue to joke about the elephant MRI.  Whenever I see him, Danny comments on the earrings I wear.  He likes their shine and asks if they are made from real diamonds. He is very brave.

Once his therapy is finished, we re-stage his cancer.  Another MRI.  Another lung CT scan.  Good news:  the tumor has responded well to the preoperative therapy.

Surgical Treatment

Now we are faced with the problem of surgery.  The tumor must be removed with wide margins.  This means that a cuff of normal tissue must be taken with the tumor to ensure that no tendrils of cancer are left inside of Danny's leg.  The tumor had extended into the knee joint, so that would need to be sacrificed.  The options are limited:

Above Knee Amputation

Because his tumor involves the joint and the end of the femur bone, Danny would need an above-the-knee amputation, "AKA".  This option ensures removal of the tumor but compromises function significantly.  Above-the-knee amputees walk slower and use 65-70% more energy than non-amputees.   These patients have great difficulty with sporting activities.

Expandable Prosthesis

There are some knee prostheses which can "grow" with a patient.  This means that some parts of them may be accessed and can be expanded over the years so that the child will have equal limb lengths.  Danny would lose the growth centers from both his femur (thigh bone) and his tibia (shin bone).  Together, these growth centers add 1.6 centimeters of height per year in the average boy.  So, if Danny were to stop growing at age 18, the loss of these growth centers would make that leg 16 centimeters shorter (about 6.3 inches).   The prosthesis would need to be accessed at intervals in order to "grow" the leg.

While this sounds like a great option, for a child with the social situation Danny has, it is less than ideal.  This type of implant would require close follow up and likely multiple later surgeries.  OK, there is practically a guarantee that Danny would need more surgery.  Also, if Danny decides to do any type of heavy labor, the knee prosthesis may be too delicate. What at first seems a great choice may not be the best one for this particular kid.

Rotationplasty

This procedure was first described in 1950 by Van Nes.  Here, all or part of the femur bone and the proximal part of the tibia bone are removed, and the end part of the tibia, along with the foot, is rotated 180 degrees.  The end of the femur bone is attached to the end of the tibia bone in this new position, and the bones heal together as would a fracture.  The end result is a shortened leg with the foot on "backwards."   So the heel of the foot ends up  where a normal kneecap would be, and the flipped-around ankle joint is used as the knee joint. 

So instead of acting like an above-the-knee amputation ("AKA"), this surgery allows the patient to function like a below-the-knee amputee ("BKA").  A healthy person with a BKA uses about 10% more energy during activity as would a non-amputee.  Compare this with the 65-70% more energy used with and AKA, and the advantage is clear. 

Also, the rotationplasty would allow Danny to do any kind of work in the future.  The length of the operated leg would be calculated based upon Danny's growth charts and the projected final length of his other leg so that his legs would be of equal length at maturity.

The Choice

Danny and his family decide upon rotationplasty as his best option.  Even though I am no longer on rotation with Dr. Shives, I am allowed to scrub on the case.  We remove the entire tumor and turn Danny's leg around, fix the bones together with plate and screws and reattach the muscles so that the ankle will work as a knee.  His leg is placed in a splint after surgery and is immobilized until the bones heal together.

Recovery

Danny's mother and father  cannot be there on the day of the surgery.  His aunt brings him to the hospital but then needs to make the 400 mile trip home in order to go to work the next day.  So Danny and I are together again in his hospital room that evening.  We joke about the elephant MRI.  Over a chocolate shake from McDonalds, we were hopeful about Danny's being able to play basketball again in a few months.  We talk about his mother and the fact that he would be able to move back in with her once she pays her water bill.  Once he finishes his next rounds of chemotherapy.  Once his leg heals and he can wear a prosthesis. 

Cancer-Free

The last time I see Danny, he is a tall, healthy 12 year-old boy.  He has already outgrown three below-the knee prostheses and plays basketball almost every day with his friends.  He does well in school even though there are still ups and downs with his family life.   

There are no signs of his cancer.

The last time I see Danny, he gives me a pair of earrings, made by a woman on his reservation.  They're much better than any diamonds I have. 

photo: above from The New England Journal of Medicine.  The earring photo is mine.