Is explantation of Polyetheretherketone (PEEK) cranioplasty medically necessary in a patient with significant purulence, phlegmonous material, and a loose, fractured implant?

Explantation of Infected PEEK Cranioplasty is Medically Necessary

Yes, explantation of the PEEK cranioplasty is medically necessary in this patient with significant purulence, phlegmonous material in the subgaleal and epidural spaces, and a loose, fractured implant with hardware protruding through the wound. 1

Definitive Criteria for Prosthetic Implant Infection Met

The patient meets multiple definitive criteria for prosthetic implant infection based on established guidelines:

• The presence of purulence without another known etiology surrounding the prosthesis is definitive evidence of infection and mandates removal 1
• The intraoperative findings of "significant purulence and phlegmonous material" in both the subgaleal and epidural space constitute unequivocal evidence of implant infection 1
• The loose implant with fractured plates and hardware protruding into the drainage site represents mechanical failure compounding the infection 1

Why Retention is Not an Option

Debridement with implant retention is contraindicated in this case for several critical reasons:

• The implant is mechanically compromised (loose with multiple fractured plates), which precludes successful retention even if infection could be controlled 1
• Hardware is protruding through soft tissue, creating a direct communication between the implant and external environment—analogous to a sinus tract, which is definitive evidence requiring explantation 1
• The presence of epidural space involvement indicates deep infection that cannot be adequately debrided without implant removal 1

Infection Management Algorithm for This Case

Immediate surgical management:

• Explant the entire PEEK cranioplasty system including all hardware 1
• Obtain at least 3-5 intraoperative tissue samples for aerobic and anaerobic culture before administering additional antibiotics (though empiric therapy has already been started) 1
• Perform thorough debridement of all infected and necrotic tissue in the subgaleal and epidural spaces 1

Antimicrobial therapy:

• Continue the already-initiated broad-spectrum empiric coverage with vancomycin and cefepime until culture results return 1
• Once organisms are identified, transition to pathogen-specific therapy for 4-6 weeks of intravenous antibiotics 1
• The 2-week antibiotic-free window to optimize culture yield is no longer applicable since empiric therapy has been started 1

Reconstruction Timing

Delayed reconstruction is strongly recommended:

• Do not attempt immediate reimplantation given the extent of purulence and tissue involvement 1
• Complete the full course of pathogen-specific antibiotics (4-6 weeks) 1
• Allow adequate time for soft tissue healing and resolution of inflammation before considering delayed cranioplasty 2, 3
• When reconstruction is performed, consider vascularized soft tissue coverage if the wound bed appears compromised 2

Critical Pitfalls to Avoid

Do not attempt implant salvage in this scenario:

• Unlike some prosthetic joint infections where debridement with retention may be considered, this patient has both mechanical failure AND deep infection 1
• The fractured, loose implant cannot provide structural integrity even if infection were controlled 4, 5
• Attempting retention would lead to treatment failure and potentially life-threatening complications including intracranial abscess or meningitis 3, 5

Do not delay explantation:

• The proximity to brain parenchyma and presence of epidural involvement creates risk for devastating CNS complications 3
• Mortality and morbidity increase significantly with delayed treatment of infected cranial implants 4, 5

Evidence Quality Considerations

The recommendation for explantation is based on high-quality Infectious Diseases Society of America guidelines for prosthetic infections 1, which establish that purulence surrounding a prosthesis is definitive evidence requiring removal. While these guidelines specifically address prosthetic joint infections, the principles directly apply to cranial implants, particularly given the additional mechanical failure present in this case. The PEEK-specific literature 4, 3, 5 consistently reports infection rates of 7-13% requiring explantation, with successful outcomes following removal, antibiotic therapy, and delayed reconstruction.

The combination of definitive infection criteria, mechanical implant failure, and deep tissue involvement makes explantation the only medically appropriate intervention to prevent serious morbidity or mortality. 1, 4, 3