Benign Bone Tumors
Examples of benign bone tumors include enchondroma, fibrous dysplasia and giant cell tumor of the bone. Not all benign bone tumors require surgery. Some tumors are simply treated with observation.
For tumors where surgery is required a "curettage-resection" is performed. This is where the tumor is removed from inside the bone. Metal curettes and a high-speed burr are typically employed.
> An example of curettage-resection performed using both hand instruments and motorized burring
Once the tumor is removed, the bone "defect" is reconstructed using various techniques. This may include the use of metal rods, plates and bone graft or cement. Newer implant designs adapted from orthopedic trauma surgery, such as "locking" plates and "inflatable" rods allow for improved bone stability, sometimes with less morbidity to the patient.
> An example of use of locking periarticular plate to reconstruct the tibia, adjacent to the knee joint.
Malignant Bone Tumors
For malignant tumors of bone, a “wide resection” is performed. This means that the tumor is removed with a surrounding area of normal bone and soft tissue. Examples of malignant bone tumors include osteosarcoma, Ewing's sarcoma and chondrosarcoma.
In many cases, the patient undergoes chemotherapy before and after surgery. This helps shrink the tumor and make surgery safer and easier. For more information, refer to the American Academy of Orthopedic Surgeons (AAOS) webpage on limb-sparing surgery.
Since many malignant tumors affect the ends of bones, it is common to have to replace a joint along with the bone–most commonly the knee or hip joint. In these cases, an endoprosthesis (an implanted prosthesis) is used to replace the portion of bone and adjacent joint. Endoprosthetic design has advanced tremendously and now off-the-shelf implants can be used to reconstruct almost any bone defect. The implants are modular, meaning they are assembled at the time of surgery from component pieces.
> An example of a tumor of the distal femur being replaced with a metal prosthesis that includes an artificial knee joint
Bone Tumors in Children
When a bone tumor affects a child, not only must the surgeon reconstruct the missing bone, the surgeon must also plan for the child's future growth. In these cases, an expandable prosthesis is used. New implant designs allow for expansion of the prosthesis without a surgical procedure. Using the Repiphysis™ endoprosthesis, the length of the leg can be periodically lengthened by applying an electromagnetic force around the knee. The limb can be lengthened more frequently, with less pain, and the child is able to avoid multiple, painful surgical procedures.
> See the implant lengthen when a specially-designed electromagnetic coil is placed around the knee. (Images courtesy of Wright Medical.)
> As the electromagnet heats the inside of the prosthesis, a built-in spring pushes out and lengthens the implant.
Metastatic Bone Tumors
Benign bone tumors and metastatic bone tumors are often treated similarly, by performing a curettage-resection of the bone lesion and using cement and metal plates/rods to reconstruct the bone defect. Radiation is frequently employed, in addition, for metastatic bone tumors. Some of the more aggressive metastatic tumors, such as renal cell carcinoma, also undergo cryosurgery to further reduce the risk of the tumor recurring.
For tumors that affect the hip joint, a partial hip replacement ("hemiarthroplasty") is often performed. This portion of the skeleton is under tremendous load and thus it is more effective to replace it than to repair it.
> Patient with metastatic breast cancer in hip region who underwent hemiarthroplasty
Benign and Malignant Soft Tissue Tumors
Benign Soft Tissue Tumors
Benign soft tissue tumors can be slow-growing, with low chance for recurrence, or aggressive, with higher chance for recurrence. An example of a slow-growing tumor would be lipoma. Examples of aggressive benign tumors would be fibromatosis or pigmented villonodular synovitis (PVNS). Sometimes the location (such as within a joint for PVNS) or the appearance on MRI scans (such as with lipoma), can accurately predict the diagnosis. However, biopsy is usually required. Usually, no additional muscle is removed for benign soft tissue tumors ("marginal" resection).
For aggressive lesions, however, more aggressive surgery is performed and sometimes radiation is used after surgery to help prevent recurrence. In addition, more frequent follow-up imaging (usually MRI) is performed after surgery.
> Lipoma seen on MRI and being surgically removed
> PVNC of the knee with large areas of tumor inside and outside the knee
Malignant Soft Tissue Tumors
Most malignant soft tissue tumors of the extremities are sarcomas. In general, sarcomas respect anatomic boundaries and, thus, surgical removal of the tumor with an intact covering ("margin") of normal tissues is adequate to prevent the tumor from recurring. In planning surgery, the "grade" of the tumor is taken into account. The higher the grade, the higher the risk of recurrence and more aggressive surgical and non-surgical treatment is required.
Muscle Flap Coverage
In certain situations, tissue from another part of the body is used to fill the defect. This can be a nearby muscle that is rotated into position or a piece of muscle detached entirely and sewn into place with its feedling blood vessel intact ("free flap"). This type of procedure is performed in conjunction with a plastic surgeon.
Neoadjuvant (Pre-operative) Radiotherapy
Radiation administered before surgery is referred to as "neoadjuvant" radiation (and as "adjuvant" radiation when it is administered after surgery). For bone sarcomas, both neoadjuvant and adjuvant chemotherapy are given. This practice was established many years ago when it was found that it allowed for limb-sparing surgery in situations where the size of the tumor may have otherwise required amputation and that it did not significantly increase surgical complications For soft tissue sarcomas, neoadjuvant radiotherapy has been used for high-grade (rapidly-growing) soft tissue sarcomas with the same rationale.