Progress of Antibiotic-Loaded Bone Cement in Joint Arthroplasty

Periprosthetic joint infection (PJI) remains a devastating complication following total joint arthroplasty. Bone cement, composed of polymethyl methacrylate (PMMA), has been integral to prosthesis fixation since the 1960s. However, its inherent lack of antimicrobial activity led to the introduction of antibiotic-loaded bone cement (ALBC) in 1970. Despite decades of use, emerging challenges like antibiotic resistance, high-risk patient populations, and evolving pathogens necessitate advancements in ALBC technology. This article synthesizes the latest research on ALBC, focusing on antimicrobial efficacy, elution kinetics, mechanical properties, novel additives, and clinical applications.

Antimicrobial Capacities of ALBC

Anti-Staphylococcal Agents
Staphylococcus species, particularly S. epidermidis (35%) and S. aureus (21%), dominate PJI cases. Gentamicin, a traditional ALBC antibiotic, faces resistance in 66% of Staphylococcus isolates. Combination therapies show promise:

Daptomycin + Gentamicin: Reduces the minimal biofilm eradication concentration (MBEC) against gram-positive bacteria, with 40 g PMMA containing 1.5 g daptomycin and 0.5 g gentamicin proving optimal.
Vancomycin: Maintains efficacy against methicillin-resistant S. aureus (MRSA) for four weeks in vitro.
Ceftaroline: At 3 wt% (1.2 g/40 g cement), elutes above MRSA’s MIC for six weeks.
Teicoplanin achieved a 96% eradication rate in Staphylococcus PJIs, while rifampin combinations improved gentamicin’s anti-biofilm activity.

Anti-Fungal Agents
Fungal PJIs, though rare (0.9% of 3,525 cases), have high recurrence rates (24–62%). Liposomal amphotericin B or amphotericin with carriers like sodium deoxycholate enhances elution without compromising mechanical strength. Econazole and fluconazole inhibit Candida spp. but reduce cement strength below weight-bearing thresholds.

Antibiotic Elution Kinetics

Elution follows a biphasic process: an initial “burst release” from surface-embedded antibiotics and sustained “continuous release” from deeper particles. Key factors influencing elution include:

Antibiotic Properties: Hydrophilic antibiotics (vancomycin, daptomycin) release faster than hydrophobic ones. Synergistic combinations (vancomycin + tobramycin) increase cumulative elution by 38%.
Dosage: Higher doses (e.g., 4 g vancomycin/40 g PMMA) boost elution but risk mechanical weakening.
Mixing Methods: Hand-mixed ALBC releases 23–30% more vancomycin than commercial pre-mixed versions due to increased porosity. Vacuum mixing extends gentamicin release by 30% over seven days.
Polymerization Temperature: High exothermic reactions (70–120°C) degrade heat-sensitive antibiotics (β-lactams). However, ceftazidime retains 90% bioactivity post-curing.
Sonication: Low-frequency ultrasound (40 kHz, 5–30 min) enhances elution by disrupting cement pores.

Mechanical Performance

ALBC’s mechanical integrity depends on polymerization and antibiotic interaction:

Antibiotic Type: Gentamycin reduces compressive strength to 65 MPa (vs. 92 MPa for plain PMMA). Rifampin’s hydroquinone disrupts polymerization, lowering strength by 40%.
Dosage: Adding 1 g vancomycin decreases bending strength by 15%; 4 g causes 30% loss. Multi-drug ALBC (e.g., gentamycin + clindamycin) further exacerbates structural fatigue.
Physical State: Liquid gentamycin (240 mg) lowers impact strength below weight-bearing thresholds, unlike powdered formulations.

ALBC Modification Additives

Porogens
Hollow titanium dioxide nanotubes (TiO₂) increase porosity, enhancing gentamicin release while maintaining >70 MPa compressive strength. Carboxymethylcellulose improves econazole elution but compromises mechanical stability.

Sustained Release Systems

PLGA Microspheres: Prolong daptomycin release over 60 days via biodegradation.
Silica Nanoparticles: Boost vancomycin elution by 50% without altering cement’s modulus.
Calcium Polyphosphate: Mimics bone structure, extending ceftazidime release while preserving compressive strength (85 MPa).

Inorganic Antimicrobial Agents

Silver Nanoparticles: At 1% wt, reduce S. epidermidis biofilm by 99% but lack tissue penetration.
Copper-Doped Glass: Releases Cu²⁺ ions effective against MRSA, with no cytotoxicity at <5% wt.

Organic Antimicrobial Agents

Quaternary Ammonium Dendrimers: 10% wt formulations inhibit gram-positive bacteria for 30 days.
Antimicrobial Peptides: Short α-helical peptides reduce biofilm formation by 80% in osteomyelitis models.

Clinical Applications

Multidrug ALBC

Vancomycin + Ceftazidime: In 8 PJI cases, achieved infection clearance in 75% with serum drug levels >MIC for 6 weeks.
Gentamycin + Clindamycin: Zero reinfections in 32 high-risk patients over five years.

ALBC Spacers
Spacers are critical in two-stage revisions but face mechanical complications (45% dislocation/fracture). Innovations include:

Reinforced Spacers: Stainless steel intramedullary rods reduce failure rates to 6.7% in interim periods.
Custom Templates: Dental silicone molds create anatomically accurate spacers with 77% first-stage success.

Partial Revision
Retaining well-fixed components with ALBC spacers reduces surgical trauma:

One-Stage Revision: 92.3% infection control vs. 94.9% for two-stage, ideal for elderly/low-demand patients.
Hip Spacers: ENDO technique using dual mobility liners improves Harris Hip Scores from 34 to 48 post-interim.

Systemic Considerations

Antibiotic Synergy: ALBC must complement systemic therapy, as local elution alone fails to eradicate deep-seated pathogens.
Toxicity: Serum vancomycin levels post-ALBC correlate with renal injury (27% RIFLE criteria), necessitating dose adjustments in renal impairment.

Future Directions

Emerging strategies include personalized release systems (calcium phosphate-PMMA cores), immunomodulatory studies (elevated IL-6/CRP with gentamicin), and novel antifungals. Addressing mechanical-antibiotic trade-offs and optimizing multi-drug combinations remain priorities.

DOI: 10.1097/CM9.0000000000001093

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