Extended curettage for benign tumours
Extended curettage is an attempt by either mechanical, chemical, or thermal means to extend the margin of the intralesional excision to decrease the recurrence rates. Common adjuvants used include liquid nitrogen, phenol, methyl methacrylate, high-speed burr, and argon-beam coagulation. Use of adjuvants in combination with intralesional curettage has decreased recurrence rates to 2% to 13%.
Initially, the lesion is curetted from the original cortical window. Using the high-speed burr, the window is further opened exposing more tumor. This is curettage, irrigated, and the high-speed burr is again used to further open the cortical window.
Adequate resection of the lesion requires complete visualization of the bony defect. The cortical window is large enough when the entire cavity is exteriorized. This is the key portion of the procedure. The mistake that is made here is that in an attempt to minimize the size of the cortical defect, tumor cells are left behind on the deep side of the cortical bone just adjacent to an inadequate cortical window (Fig. 4).
Once the lesion is completely exteriorized, alternate with curettage, high-speed burr, and irrigation until the entire cavity is normal bone. At this point, the argon-beam coagulator is used to paint the entire surface of the cavity. As the argon-beam coagulator is applied the color of the bone changes to black as carbon is deposited.
After the entire cavity is ‘painted black’, the cavity is thoroughly irrigated. The defect is now ready to be reconstructed. Specific reconstruction technique depends on the histology of the lesion and the risk of recurrence. In cases of a giant cell, tumor bone defects are reconstructed with PMMA (bone cement).
PMMA provides immediate skeletal stability and facilitates postoperative surveillance for recurrence. If a bone graft is used it is sometimes difficult to differentiate between graft resorption and tumor recurrence, based on plain radiographs. In most other benign diagnoses allograft or autograft is used to reconstruct the bone defect. Consideration of a combination of preoperative planning and an ultimate intra-operative bony defect is used to determine if prophylactic
fixation is required.