Case #5 - Pediatric Rotating Hinge Knee Case Study
Brian McGrath, M.D.
History:
An eleven-year-old female presented to Roswell Park Cancer Institute with an osteosarcoma of the left distal femur. Her preoperative x-rays and MRI were evaluated and the proximal resection margin was determined, her preoperative x-rays indicating a resection margin were sent to the PMI Department. She received 3 months of preoperative chemotherapy and surgery was scheduled to remove her distal femoral osteosarcoma utilizing a limb salvage technique, for her chemotherapy "window".
Pre-Operative X-rays:
Pre-Operative Planning:
The preoperative x-rays show the raised periosteum and mixed osteoblastic and osteolytic response in the left distal femur indicating the bone tumor. The proximal resection level of the distal femur bone tumor was marked, including an extra margin to insure complete removal of the tumor. The PMI Department then generated an x-ray template showing the standard line and reduced size implants required to reconstruct the young girl's left distal femur. The components include a reduced (pediatric) segmental distal femoral component, a standard Oncology Salvage System (OSS) intercalary segment and a porous coated, bowed intramedullary stem for the femur. On the tibial side, a reduced tibial baseplate was proposed, which has the cruciate fins reduced in size and the one-piece stem was reduced in size to accommodate the small intramedullary canal. The surgeon reviewed the template of the components, and gave the PMI Department his approval on May 10, 2002 to proceed with the manufacturing process. At that point the surgery was scheduled for May 21, seven business days after the design approval. The PMI Manufacturing team immediately started machining the components and was able to complete the manufacturing in three days in order to send the implants to the sterilizer and ship the components in five business days. The order was then shipped to arrive the day before the planned surgery.
Surgical Procedure:
The surgery was successful in removing the bone tumor with a safe margin. The reduced segmental femoral component was utilized in conjunction with a standard OSS intercalary segment and the segmental stem to produce an 18cm distal femoral replacement. He implanted the tibial baseplate and was able to spare the epiphyseal growth plate on the proximal tibia, which will enable her proximal tibia to continue to grow, as she gets older. The reduced size femoral component was critical in allowing an adequate closure in the operating room, and the porous coated stem was appropriately sized to provide excellent fixation in the femur. The patient is currently free of disease and recovering well with her reduced rotating hinge knee. Her activities include physical therapy, school and chemotherapy.
Post-Operative X-rays:
