DISCUSSION
In any type of bone trauma and fracture, there are different factors that must be taken into account for a successful intervention. In mandibular fractures, the reconstruction must be focused to maximize function and to produce an aesthetically pleasing appearance following primary or secondary surgery2-11.
Particularly in this case, the first surgical approach was not successful, deriving in a case of Osteomyelitis with uncomfortable symptoms and complications for the patient, in addition to the need of a secondary surgical process. Postsurgical Osteomyelitis of the mandible is rare and appears to affect more men than women. The caseload of jaw osteomyelitis seems to have decreased considerably over the last fifty years thanks to the progress made in the field of oral hygiene, the appearance and the use of antibiotics, and early screening12.
In this case, the patient had multiple risk factors for mandibular fracture which should have been identified in order to prevent the later Osteomyelitis. One of them was the smoking habit. Research shows that smoking may have detrimental effects on the skeletal system, leading to lower bone mass and mineral density. Furthermore, smokers submitted to orthopedic surgery have an increased risk of delayed fracture healing, complications (e.g., infections and non-union fractures), and longer hospital stays8. Also the patient had alcohol induced hepatic cirrhosis that tends to deteriorate both trabecular and cortical bone microarchitecture increasing the susceptibility to low-trauma fractures. The cannabinoid and cocaine abuse must be emphasized. Studies have shown that the central nervous system, including neurons and glial cells, plays an important role in regulating bone metabolism and therefore in the pathology of osteoporosis through cannabinoid receptors (CB1 and CB2), which are involved in pain modulation6. Cocaine causes both local anesthesia and vasoconstriction. The vasoconstriction may lead to necrosis, chemical irritation, mechanical trauma, bacterial infection, immunosuppression, and osteoblast inhibition. The combination of decreased oxygen tension, inflammation, irritation, and open wounds creates an ideal environment for infection with common4-13.
The abuse of multiple drugs and comorbidities in this case may have increased the susceptibility from the patient to the osteomyelitis after his first intervention and later poor osseointegration of the surgical plates after the second surgery.
In this case a two-step surgery with external fixations was chosen, due to the conditions in which the patient arrived at the Hospital. The research on the field of external fixations shows that the main indications for its use are large bone loss caused by tumor resections, infections leading to multiple bone sequestration, comminution and severe trauma with substance loss2-14-15. In cases such as this one, where large bone defects are present, a first approach with internal fixation surgery has an inherent high risk of nonunion and infections. The aim of the external fixators is to maintain the best patient anatomy and reduce pain, before they can benefit from optimal secondary reconstructive surgical procedure14. It must be also taken into account that, because of the general nature and severity of the mandibular fractures treated by external fixation, a high complication rate of up to 35% has been reported. Postoperative infections, cellulitis around the pins, nonunions, malocclusions, and pin loosening are potentially frequent with this fixation technique. External fixation remains a quick, safe, and simple method to treat mandible fractures in selected clinical situations15.
Recently, computer-assisted navigation technology has become common in many medical fields. Its advantages include improvements in the accuracy of maxillofacial bone surgery, avoiding injury to vital structures, shortening of the operation time reducing flap ischemia duration and is cost-effective, despite the expensive technology1, 15-16. Maxillofacial reconstructive surgery requires a high standard of surgical precision and dimensional errors are low in 3D printing, with discrepancies between STL models and 3D-printed models typically smaller than an imaging voxel (< 1 mm), being highly accurate in the surgical planification, compared with conventional surgery16. Also, Computer-assisted surgery (CAS) offers the ability to plan osteotomies, mirror the unaffected mandible, evaluate the bone plate relationships for positioning of dental implants, create surgical resection guides and fabricate patient-specific reconstruction plates1-16.
In cases of large bone loss like as the one seen in this case report, the use of VSP and CAS could be beneficial for predictive outcomes and high standard esthetic and functionality in the maxillofacial area.
The non-vascularized iliac crest graft was chosen for this case for multiple reasons. The main reason being the severe compromise of blood vessels due to previous surgeries, restricting the chances of a successful anastomosis in a vascularized graft10-17. In this case the facial skin envelope and soft tissue volume was preserved, so no soft tissue graft was needed1. Given the size of the bone loss (6cm) iliac crest graft was used because of the high success rate in less than 7cm defects, presentation of a high quality bone bulk, large amounts of bone marrow and resemblance with the curved lateral surface of the mandible10. Iliac crest donor site can be the first choice in isolated, short segment bone defects of mandible without soft tissue defect, which are resulted from trauma or tumor resection10-17. Also non-vascularized iliac crest bone grafts used to reconstruct defects of 7 cm or less have an 83% success rate1.
In conclusion, multiple factors can be extrapolated from this case like habits, comorbidities and personal adhesion to therapy may be important in the prognosis of the final treatment. External fixations could be a good intermediate alternative for patients that require complex surgery, which may be previously planned due to virtual surgical planning with 3D printing. The aforementioned in conjunction with the correct graft choice, could aid to a predictable, aesthetically and functionally successful treatment.