Abstract
This case report details the treatment of a 58-year-old male patient with a complex medical history, including renal transplants, immunosuppression and anticoagulation therapy. The patient developed skull osteonecrosis complicated by Pseudomonas osteomyelitis following treatment for squamous cell carcinoma of the scalp. After multiple failed reconstructive surgeries and advanced wound care attempts, an innovative chelator-based bone debridement strategy was implemented as part of an advanced wound care plan at home. This approach led to >50% reduction in the area of bone exposure and eliminated Pseudomonas aeruginosa from bone cultures.
Ethical approval and patient consent
Institutional ethics board/institutional review board approval was not indicated or required for this case study. Written, informed consent was obtained from the patient regarding the treatment protocol as well as publication of photographs.
Case report
The patient was a 58-year-old male with a significant medical history, including two renal transplants requiring immunosuppression (prednisone and sirolimus), multiple skin cancers, anticoagulation therapy with rivaroxaban due to lupus anticoagulant syndrome, and an automatic implantable cardioverter-defibrillator (AICD) for a history of ventricular tachycardia.
Initial treatment course
In 2014, the patient was diagnosed with SCC of the scalp, necessitating surgical resection, chemotherapy and radiation therapy. By 2015, he presented with a non-healing scalp wound and evidence of osteoradionecrosis. Initial management by a community ear, nose and throat (ENT) physician involved attempts at reconstruction using an anterolateral thigh free flap, a right latissimus flap, and grafting with a mesh-based cellular tissue product, all of which failed.
The patient was referred for an omental free flap at an out-of-state academic medical center but eventually sought care at an in-state academic medical centre’s ENT department. In 2017, an academic ENT surgeon performed an outer-table craniectomy to debride nonviable bone, followed by grafting with another meshed cellular tissue product and negative pressure wound therapy (NPWT), both of which were unsuccessful. During this time, the patient was diagnosed with osteomyelitis due to Pseudomonas aeruginosa and Serratia marcescens, prompting a prolonged course of antibiotics. Following this, a split-thickness skin graft was applied to the exposed skull, which initially took but then failed as patches of the calvarium began protruding by mid-2018. Given the bleeding risk and history of multiple failed grafts, further operations were deemed unsuitable. A second opinion from another academic ENT cancer centre also concluded that no further interventions could be offered. With limited options and the need for continued, possibly palliative management, the patient was referred to us for mobile wound care.
Innovative treatment approach
Upon initial evaluation, the patient was restarted on high-dose cefepime and received standard treatment for approximately 1.5 months. It became clear that without debridement and control of the osteomyelitis, the wound and skull would continue to deteriorate. In reviewing various literature and consulting with a general dentist, the authors developed a novel approach using ethylenediaminetetraacetic acid (EDTA)-based chelation for bone demineralisation to achieve gentle, controlled bone debridement.
In dental practice, chelator preparations, such as RC Prep (Premier Dental, US), are used to chemically soften root canal dentine and dissolve smear layers for further instrumentation. After confirming no prominent bony defects or other underlying pathologies with a cranial computed tomography, and obtaining informed consent, we applied a thin film of RC Prep to small areas of the exposed, non-viable skull with greenish discolouration. The applied area was then covered with xeroform dressing to maintain moisture. Debridement was performed every 48–72 hours using a curette. Unlike previous attempts, the treated bone had a paste-like consistency and was easily removed without significant force. This gel effectively softened the necrotic bone, allowing for controlled debridement. Cefepime continued for a further eight weeks after starting RC Prep. Within the first month, there were visible improvements, with the disappearance of the greenish discolouration and coverage of previously exposed bone with surrounding tissue. Pathology confirmed acute osteomyelitis in one of the debrided fragments. Pseudomonas aeruginosa, which had been consistently isolated since 2017, was no longer present in cultures. After five months of treatment, the patient chose to pause debridement due to travel plans.
Fig 1. A 58-year-old male patient with a significant medical history, and who developed skull osteonecrosis complicated
by Pseudomonas osteomyelitis following treatment for squamous cell carcinoma of the scalp. (a) ??; (b) ??; (c) ?? (d) ?? (e) ?? [AQ5: please provide captions for each image]
Outcome
By this time, there was >50% reduction in the area of exposed bone, and no greenish, necrotic bone remained. The use of RC Prep gel significantly improved wound management, offering a promising adjunctive treatment for controlled bone debridement to achieve optimal wound healing.
Follow-up
The patient eventually returned for follow-up after 11 months. The greenish discolouration had returned to the bone that remained exposed when treatment was paused; however, the areas where healthy tissue had covered previously debrided bone remained largely intact.
Discussion
This case presents an innovative and unconventional application of a known treatment modality in managing complex, refractory cranial osteomyelitis in the setting of osteonecrosis. The use of chelators, such as RC Prep, to facilitate controlled bone debridement highlights the potential for cross-disciplinary solutions in wound care. Similar approaches could be applied to other wound care cases where frequent, incremental bone debridements or biopsies are needed for optimal healing outcomes.
