Early experience of autologous graft, hydroxyapatite & calcium sulphate antibiotic paste in revision hind-foot & ankle arthrodesis

T. Howard, J. Giddie, I. Riechert, R. Ahluwalia

Background: Revision arthrodesis on a background of infection carries high risks. We describe a new technique combining adjuvant antibiotic loaded bio-composite autologous bone graft layer technique coupled with rigid fixation in definitive surgical reconstruction.

Methods: Patients who underwent revision foot and ankle arthrodesis for proven/suspected infection were included. Standard work-up including local aspiration, bone-biopsy, definitive radiology and MDT-discussion. Definitive arthrodesis involved debridement of infected scar tissues, multiple biopsies as either part of a staged or definitive process. All bone voids were measured intra operatively and classified according to volume. At definitive arthrodesis pelvic autograft (cancellous/cortical/structural) was mixed/layered with a 40% hydroxyapatite (HA), 60% calcium sulphate (CaS) paste with appropriate antibiotic to fill the void; followed by compression fusion. Empirical/pathogen specific antibiotics were given until sample-specific-antibiotics were identified. All patients were followed up for a minimum 1 year & AOFAS scoring undertaken.

Results: 20 patients meet the inclusion criteria, and were prospectively followed up, M:F ratio (n = 1:1), mean age 52.7yrs, 25% were smokers. Surgical indications following deep sampling for revision arthrodesis: Infected non/mal-union (n=14), Aseptic-loosening (n=6). Voids defects at the time of surgery were: < 1cm³ (n=2), 1 - 1.5 cm³ (n=8), 1.5 - 2cm³, (n=8), 2 - 5cm³ (n=2). 12 pts were treated with Vancomycin, 8 with Gentamicin paste depending on bacterial advice and pre-operative sampling. No-patients were lost to follow-up; 87.5% were united on imaging and mean time to independent-ambulation was 2.9 months (functional weight bearing was reached at 1.1 months). Two-patients had radiographic evidence of non-union 1-asymptomatic, & 1-requiring revision surgery (void >3cm). Two-patients remain under review. The average AOFAS score was 82.8; no-patients were treated for post-operative-infection.

Conclusions: Layered-autologous bone-grafting, with adjuvant-antibiotic loaded bio-composite and rigid fixation has been shown to be effective and safe in revision arthrodesis with low co-morbidities in void gaps are less than 2cm³.