In chronic osteomyelitis and fracture-related infection, appropriate antibiotic therapy does not by itself guarantee infection control. Infection may still recur when devitalised tissue remains in place. At that point, the problem is no longer purely microbiological. It is also structural and biological. Necrotic bone, impaired local conditions, and residual dead space can continue to support persistence even when antimicrobial therapy is active.
Summary
Long-term infection control in bone infection remains closely linked to adequate debridement.
Retained devitalised tissue limits effective antimicrobial access and preserves sites of persistence.
Local antibiotic delivery improves exposure but does not remove necrotic bone or eliminate residual dead space.
Current fracture-related infection frameworks place debridement and dead-space management at the centre of treatment.
Why This Matters
Chronic bone infection is a long-term problem rather than a short-term microbiological event. In a cohort of 100 patients followed for 1 to 12 years after treatment with gentamicin-PMMA beads, 92 were classified as healed, yet 17 recurrences still occurred over time. Lack of wound dryness and clinical improvement within 1 to 2 weeks was taken as a sign that further healing was unlikely without renewed debridement and bead exchange. Infection control was therefore judged by longer-term outcome rather than by initial response alone (Walenkamp et al., 1998).
This matters because antibiotic activity alone does not explain infection control in bone infection. In current fracture-related infection treatment frameworks, dead space is described as an active pathological environment characterised by poor perfusion, low oxygen tension, acidic pH, inflammatory mediators, and a surface favourable to bacterial attachment. Within this framework, debridement is not simply a means of reducing bacterial burden. It changes the local conditions in which any subsequent systemic or local antibiotic has to work (Metsemakers et al., 2020; Metsemakers et al., 2020).
What the Evidence Shows
Long-term infection control remains vulnerable to recurrence when infected tissue is not fully removed. Long-term follow-up extending to 12 years showed that recurrence remained part of the disease course despite combined surgical and local antibiotic treatment, and repeated debridement was built into the treatment approach when early wound progress remained unfavourable. That pattern distinguishes early improvement from longer-term infection control and helps explain why chronic osteomyelitis outcomes continue to hinge on surgical adequacy even when local antibiotics are used (Walenkamp et al., 1998).
Antibiotic exposure can be high while the structural basis for persistence remains unchanged. Measurements after gentamicin-loaded cement showed wound drainage concentrations of about 100 µg/ml in the lower-dose group and about 308 µg/ml in the higher-dose group, while serum levels remained low, with a maximum of 2.9 µg/ml and values below 1 µg/ml after 24 hours. These data help explain the appeal of local antibiotic delivery, but pharmacokinetic findings alone do not establish clinical superiority. High local concentration improves exposure. It does not by itself remove necrotic tissue or eliminate residual dead space (Wahlig et al., 1984).
Experimental in vivo data show better infection control with debridement plus antibiotics than with antibiotics alone. In a murine post-traumatic osteomyelitis model, combined debridement and antibiotics produced massive reduction or eradication of S. aureus across three detection methods, whereas sole antibiotic therapy did not sufficiently treat osteomyelitic bone. Previously infected debrided bone also showed impaired new bone formation compared with debrided non-infected controls, showing that infection control and biological recovery are related but not identical problems (Wagner et al., 2016).
Current treatment frameworks position local antimicrobials as an adjunct to surgery rather than a substitute for inadequate clearance. Dead space is treated as biologically active, and local antimicrobials are framed as a way to overcome delivery limitations of systemic therapy after adequate debridement. In that setting, local antibiotic use becomes part of a broader surgical strategy, but not a standalone solution. This distinction separates the role of antibiotic carriers from the role of surgical source control (Metsemakers et al., 2020; Metsemakers et al., 2020).
Mechanisms Behind the Pattern
Compromised tissue limits reliable antimicrobial penetration. Dead space and devitalised tissue create a poorly perfused and biologically hostile local environment. That does not mean antibiotics have no access at all, but it does mean drug delivery becomes less reliable and more dependent on residual viable tissue contact and diffusion. Clinically, this helps explain why microbiological susceptibility does not guarantee infection control when non-viable tissue remains (Metsemakers et al., 2020; Yu et al., 1990).
Biofilm-associated persistence limits what antibiotic therapy can achieve. Biofilms are structured communities attached to inert or living surfaces within a self-produced matrix, constituting a protected mode of growth. Sessile bacteria are much less susceptible to antibiotics than planktonic organisms, biofilms commonly develop on dead tissue such as sequestra of dead bone, and symptoms often recur after antibiotic cycles until the sessile population is surgically removed (Costerton et al., 1999). This does not reduce bone infection to biofilm alone, but it does clarify why retained necrotic surfaces remain important sites of persistence.
Residual dead space preserves local niches in which infection may persist. Dead space is more than an empty cavity. It is a local environment in which bacterial attachment, impaired clearance, and poor biological recovery can coexist. That helps explain why debridement and dead-space management are consistently coupled in modern treatment frameworks rather than being treated as separate technical steps (Metsemakers et al., 2020; Metsemakers et al., 2020).
Practical Implications for Clinical Decision-Making
Microbiological susceptibility does not by itself predict infection control when devitalised tissue remains (Walenkamp et al., 1998; Wagner et al., 2016).
High local antibiotic concentrations should not be interpreted as equivalent to adequate source control (Wahlig et al., 1984).
Comparisons between local antibiotic strategies can be misleading when the quality of debridement and soft-tissue management is not clearly described (McKee et al., 2002; Metsemakers et al., 2020).
In fracture-related infection, local antibiotic delivery is best understood as part of a broader surgical strategy rather than as an independent solution (Metsemakers et al., 2020).
Common Pitfalls
Mistaking high local antibiotic concentrations for adequate infection clearance. Exposure and source control are not the same problem (Wahlig et al., 1984).
Treating recurrence mainly as an antibiotic mismatch. Long-term osteomyelitis data repeatedly point back to retained infected or devitalised tissue (Walenkamp et al., 1998).
Reading local antibiotic carrier studies as if the carrier alone determined outcome. Surgical adequacy, host factors, and dead-space management remain closely intertwined with outcome (McKee et al., 2002; Metsemakers et al., 2020).
Reducing dead space to geometry alone. Current fracture-related infection frameworks treat it as a biological problem as well as a structural one (Metsemakers et al., 2020).
Closing Note
Debridement remains central in bone infection because antibiotics act within the biological conditions that surgery leaves behind. Where devitalised tissue and dead space persist, antimicrobial exposure may still be high while infection control remains difficult to achieve.
References
Walenkamp GHIM, Kleijn LLA, de Leeuw M. Osteomyelitis treated with gentamicin-PMMA beads: 100 patients followed for 1-12 years. Acta Orthop Scand. 1998;69(5):518-522. doi:10.3109/17453679808997790.
Wahlig H, Dingeldein E, Buchholz HW, Buchholz M, Bachmann F. Pharmacokinetic study of gentamicin-loaded cement in total hip replacements. Comparative effects of varying dosage. J Bone Joint Surg Br. 1984;66(2):175-179. doi:10.1302/0301-620X.66B2.6707051.
Wagner JM, Zöllner H, Wallner C, Ismer B, Schira J, Abraham S, Harati K, Lehnhardt M, Daigeler A, Kneser U, Becerikli M. Surgical Debridement Is Superior to Sole Antibiotic Therapy in a Novel Murine Posttraumatic Osteomyelitis Model. PLoS One. 2016;11(2):e0149389. doi:10.1371/journal.pone.0149389.
Costerton JW, Stewart PS, Greenberg EP. Bacterial biofilms: a common cause of persistent infections. Science. 1999;284(5418):1318-1322. doi:10.1126/science.284.5418.1318.
Metsemakers WJ, Fragomen AT, Moriarty TF, Morgenstern M, Egol KA, Zalavras C, Obremskey WT, Raschke M, McNally MA, Verhofstad MHJ, Kates SL, Borens O. Evidence-Based Recommendations for Local Antimicrobial Strategies and Dead Space Management in Fracture-Related Infection. J Orthop Trauma. 2020;34(1):18-29. doi:10.1097/BOT.0000000000001615.
Metsemakers WJ, Morgenstern M, Senneville E, Borens O, Govaert GAM, Onsea J, Depypere M, Richards RG, Trampuz A, Verhofstad MHJ, Kuehl R, Raschke M, McNally MA, Obremskey WT, Zalavras C, Moriarty TF, Verstreken F, Kates SL. General treatment principles for fracture-related infection: recommendations from an international expert group. Arch Orthop Trauma Surg. 2020;140(8):1013-1027. doi:10.1007/s00402-019-03287-4.
McKee MD, Li-Bland EA, Wild LM, Schemitsch EH. A Prospective, Randomized Clinical Trial Comparing an Antibiotic-Impregnated Bioabsorbable Bone Substitute with Standard Antibiotic-Impregnated Cement Beads in the Treatment of Chronic Osteomyelitis and Infected Nonunion. J Orthop Trauma. 2010;24(8):483-490. doi:10.1097/BOT.0b013e3181cf9b2b.