CC
A 71-year-old female with a history of multiple myeloma of the past 5 years is referred by her oncologist because of “exposed bone” and a draining fistula ( Fig. 12.1 ).
Intravenous drug–induced osteonecrosis of the jaws
Two classes of drugs have been directly linked to osteonecrosis of the jaws: bisphosphonates and reactor activator of nuclear κB (RANK) ligand inhibitors. Therefore, what was once referred to as bisphosphonate-induced osteonecrosis of the jaws (BIONJ) now is best called drug-induced osteonecrosis of the jaws (DIONJ).
The clinically important distinction is the route of administration, intravenous (IV) versus oral, versus subcutaneous across both classes of drugs. Therefore, a sample case of an oral bisphosphonate ONJ is presented in a different chapter. A sample case of an IV bisphosphonate ONJ is presented here, and sample cases of subcutaneous injections of denosumab (a RANK ligand inhibitor) are presented as different cases in the chapters that follow.
HPI
The current patient’s multiple myeloma is stated to be in remission as a result of stem cell transplantation and Velcade treatment in the past. She now takes only Revlimid, but she took zoledronic acid (Zometa) in the recent past. She took Zometa 4 mg monthly for 2 years; this treatment was discontinued 9 months ago when exposed bone and pain developed spontaneously. Since then, the exposed bone has failed to heal. The patient was initially treated with clindamycin 300 mg three times daily but without relief of pain. Pain relief was obtained when she was placed on phenoxymethyl penicillin (penicillin VK) 500 mg four times daily along with 0.12% chlorhexidine oral rinses three times daily. Despite initial pain control, the area of exposed bone increased, and two draining cutaneous fistulas developed along with a return of pain.
PMHX/PDHX/medications/allergies/SH/FH
In addition to multiple myeloma and its related treatments, the patient has had a left total knee replacement for degenerative arthritis (8 years ago) and placement of a coronary artery stent (6 years ago). She is a past smoker of one pack per day but quit 10 years ago. She takes no medications other than Zometa and Revlimid.
Examination
Exposed bone is noted in the lingual alveolar bone in the right mandibular molar area (see Fig. 12.1 A). There is a draining fistula at the level of the inferior border of the mandible (see Fig. 12.1 B). Although there is no exposed bone seen on the buccal, there is prominent exposed bone seen on the lingual, which is jagged. There are also several fistulas arising from the adjacent lingual mucosa, which suggests that the nonvital bone extends beyond the clinically exposed bone.
Imaging
A cone-beam computed tomography (CBCT) scan shows significant osteolysis in the right midbody area of the mandible and a diffuse surrounding sclerosis ( Fig. 12.2 ). Compared with a CBCT scan taken 6 months earlier, a greater amount of osteolysis and osteosclerosis is noted.
Labs
Routine laboratory testing is required to particularly assess for anemia and blood chemistry changes. This patient shows a clinically insignificant anemia, with hemoglobin of 11.3 g/dL and hematocrit of 34%. She also exhibits slightly elevated myeloma proteins (immunoglobulin G [IgG], 160.8 mg/mL; normal range, 3–19.4 mg/mL). This IgG value is still not a contraindication to nonsurgical or even surgical management of the exposed bone.
Assessment
Stage III DIONJ by virtue of its osteolysis to the inferior border threatening a pathologic fracture.
Treatment
The treatment choices discussed with the patient included palliative nonsurgical management using intermittent or ongoing antibiotic therapy, along with oral rinses of 0.12% chlorhexidine three times daily, and adaptation to long-term and probably permanent exposed bone or surgical resection to achieve resolution and a cure. Because this patient had endured the pain, odor, and foul taste of the exposed bone for 9 months already and because the bone deterioration was advancing, she chose to undergo surgical resection.
Surgical resection was performed after consultation with and clearance from her medical oncologist and her internist. The surgical access was made through a convenient neck crease to expose the right hemimandible ( Fig. 12.3 A). A 2.9-mm titanium reconstruction plate (the strongest made) then was placed and fixated onto the intact mandible with locking screws so as to index the position of the condyle and the remaining occlusion ( Fig. 12.3 B). The plate was subsequently removed, with each screw marked to correlate with the appropriate screw hole. The mandible was then resected from the right canine area to the right midramus, with the surgeon observing for residual viable marrow space as the best assessment for an adequate resection margin ( Fig. 12.3 C and D). The titanium plate was replaced and fixated in its preoperative position after the resection edges were rounded off ( Fig. 12.3 E). The mucosa and skin were closed primarily over the reconstruction plate.
