Abstract
Introduction
Antibiotic loaded absorbable calcium sulphate beads (ALCSB) are an increasingly popular adjunct in the treatment of musculoskeletal infections including osteomyelitis and peri-prosthetic joint infections (PJI). Limited data exist regarding the clinical indications and biochemical outcomes of ALCSB in PJI cases.
Aims
To determine the proportion of organisms that were sensitive to the gentamicin and vancomycin that we add to the ALCSB as a part of our treatment protocol and to determine the prevalence of postoperative hypercalcaemia when used for treatment of hip and knee DAIR (debridement and implant retention) and revision arthroplasty for PJI.
Methods
A retrospective review of 160 hip and knee revisions using ALCSB performed between June 2015 and May 2018 at a tertiary unit was performed. 10–40 cc of ALCSB was used for each case containing vancomycin and gentamicin. Data recorded included patient demographics, comorbidities, indication for surgery, operative intervention, microbiological results and serum biochemistry for calcium levels.
Results
The cohort consisted of 91 males and 69 females, with a mean age of 69.0 years (21.3 to 93.1) and mean BMI of 34.7(12.6 to 48.1). 56 (35%) had single-stage revision, 45 (28.1%) had first stage revision, 35 (21.9) had DAIR, 19 (11.9%) had second stage revision and 5 (3.1%) other procedures.
Organisms included staphylococcus aureus (30.0%), culture-negative (27.5%), staphylococcus epidermidis (18.1%), and pseudomonas aeruginosa (3.1%). 54.3% were sensitive to both vancomycin and gentamicin, 25.0% to vancomycin only and 8.6% to gentamicin only.
11.9% (19/160) of patients had transient post-operative hypercalcaemia (normal range 2.2–2.7mmol/L), peaking at day 6–7 and resolved with hydration by day 10 postoperatively. Preoperatively, 26.9% had albumin <35 g/L and 49.3% had some degree of renal impairment with an eGFR <90 ml/min.
Conclusion
The use of ALCSB allows local delivery of vancomycin and gentamicin in lower limb PJI. Organisms were sensitive to this antibiotic combination in 88% cases. Care must be taken to monitor calcium for 10 days post-operatively.
