Intro

Calcium sulphate (CS) is a recent alternative for antibiotic elution in infected bones and joints. The purpose of this study is to evaluate the use of antibiotic impregnated calcium sulphate (AICS) beads in the management of infected tibia and femur, with regards to patient outcomes and complication rates (including reinfection rate, remission rate and union rate).

Aim. To determine if systemic toxicity occurs after the use of antibiotic loaded calcium sulphate in the treatment (1) of bone and soft tissue infection. Although antibiotic loaded calcium sulphate is increasingly used for the local treatment of bone and soft tissue infection, there is little data to demonstrate that systemic levels generated by local release of antibiotics are safe. For this reason, we routinely assay systemic levels of antibiotics. Methods. Patients with osteomyelitis or soft tissue infection underwent surgical debridement and lavage of the infected tissue in routine fashion. Patients with osteomyelitis were graded with the Cierny-Mader classification. Bone cavities and soft tissue dead spaces were packed with antibiotic loaded calcium sulphate (10–40 cc) loaded with Vancomycin (1–4 g) and Gentamicin (240–960 mg). The wounds were closed over the antibiotic loaded calcium sulphate. Patients underwent serial assays of Vancomycin and Gentamicin levels on the day of surgery and the first two post-operative days. Renal function was also measured. Results. 12 limbs in 10 patients were treated for osteomyelitis or soft tissue infection. There was 1 Cierny-Mader grade 1, 3 Cierny-Mader grade 3, and 2 Cierny-Mader grade 4. Two had deep soft tissue infection alone. There were 3 type A hosts and 7 type B hosts. The patients age ranged from 24 to 89 (mean 54). In patients without renal dysfunction, the systemic levels were either unmeasurable at the first assay, or below the acceptable trough level. (Mean 2.4 and 1.8 for Vancomycin and Gentamycin respectively). They had unmeasurable systemic levels at the third assay. In patients with renal dysfunction, systemic levels were in the therapeutic range determined for systemically administered antibiotics, but these levels remained high and did not decrease until patients had undergone their routine dialysis. Conclusions. In patients treated with antibiotic loaded Stimulan, antibiotic assays are not necessary in patients who have normal renal function, as they clear the systemic absorption as quickly as it is generated. Patients with impaired renal function should have lower doses of antibiotic used for their topically applied carrier, and should undergo assays regularly to ascertain if levels are remaining below the accepted range determined for systemically administered antibiotics. If they remain high, the antibiotic loaded calcium sulphate could be removed. * Stimulan (Biocomposites, Keele, UK)

Introduction. The BOAST (British Orthopaedic Association Standards for Trauma) guidelines do advise that open pilon fractures amongst other open lower limb fractures need to be treated at a specialist centre with Orthoplastic care. The purpose of this study was to determine clinical outcomes in patients with open pilon fractures treated as per BOAST guidelines including relatively aggressive bone debridement. Methods. A retrospective analysis of a single surgeon series of open pilon fractures treated between 2014 and 2019 was conducted. Injuries were graded according to the Gustillo-Anderson classification and all patients were included for the assessment of the rate of infection and fracture healing. Functional outcome assessment was performed in all patients according to the American Orthopedic Foot and Ankle Score (AOFAS) at 6 months after definitive surgery. Initial wound with bone debridement and application of a spanning external fixator was performed within an average of 13.5 (Range: 3–24) hours. Fixation with FWF (Fine Wire Frame) was performed when the wound was healed, with the mean time from primary surgery to application of FWF being 24.5 (Range: 7–60) days. Results. There was a total of 20 patients including 16 males and 4 females. The mean age was 50.45 (Range: 16–88) years. Follow-up was for an average of 23.2 (Range: 5–51) months. There were 3 patients with Gustilo Type I injuries, 6 with Type II, 4 Type with type IIIa and 7 with Type IIIb injuries. Average time to bone union was 9.3 (Range: 2–18) months. The mean AOFAS score was 66 (Range: 15–97) points. TSF was used on 18 patients, while 2 patients had an Ilizarov frame. A corticotomy was performed on 4 patients with critical bone defect post debridement, while 2 patients had Stimulan beads with antibiotics. There was 1 case (5%) of deep infection and 9 cases (45%) of superficial infection. There were also 2 cases (10%) of non-union which required bone grafting from their femur using a RIA (Reamer Irrigation Aspirator). Other complications included 1 case of acute compartment syndrome, 1 case of pulmonary embolism, 1 case of necrotic skin and 1 case of amputation. Conclusion. Results of our study suggests that the use of staged wound debridement including relatively aggressive bone debridement in conjunction with antibiotics, external fixators and patient tailored conversion from spanning external fixator to fine wire frame achieves low rates of wound infection and complications for patients with open pilon fractures

Background. Calcium sulfate and phosphate have a long clinical history of use as bone-void fillers (BVF) with established biocompatibility and resorption profiles. It has been widely reported that the addition of ‘impurity’ elements such as Silicon, Strontium and Zinc to calcium phosphate is advantageous, resulting in an improved bone healing response. Methods. This study examined the in vivo response of two formulations of calcium sulfate, as 3mm diameter hemispherical beads, in critical sized defects created in cancellous bone of distal femur and proximal tibia (10mm diameter × 13mm depth) in adult sheep; beads prepared from recrystallised pharmaceutical grade calcium sulfate (RPCS, Stimulan, Biocomposites Ltd, UK) and a lower purity medical grade material containing 1% strontium (SrCS). The animals were sacrificed at 3, 6 and 12 weeks post implantation and the surgical sites analysed using microCT and decalcified histology. Results. Radiographic analysis showed a slower resorption for SrCS compared to RPCS. Radiographic analysis for both materials confirmed little residual beads at three weeks post implantation. Radiographs at sacrifice confirmed no adverse reactions at any sites at 3, 6 and 12 weeks. Radiographic data alone was not adequate to determine the status of the bone formation and the implant resorption at the implant site. Histological analysis confirmed little or no adverse tissue reactions to either material. However, RPCS outperformed the modified material in terms of new bone formation at all time points post implantation. At 3 weeks histology for RPCS confirmed that residual beads were still visible with active new bone growth appearing to penetrate centripetally into the defect with some resorption of the implant material. By 6 weeks significant new bone was present throughout the defect. In comparison, absorption of the modified material was slower, and penetration of new bone into the defect was less progressed. Conclusions. The rapid bone regenerative ability of the recrystallised pharmaceutical grade calcium sulfate was demonstrated. The presence of 1% Strontium impurity acted to delay implant absorption and bone healing in this model

We describe a case series using calcium sulphate bio composite with antibiotics (Cerament/Stimulan) in treating infected metalwork in the lower limb. Eight patients aged 22–74 (7 males, 1 female) presented with clinical evidence of infected limb metal work from previous orthopaedic surgery. Metal work removal with application of either cerement in 5 cases (10–20ml including 175mg–350mg gentamycin) or stimulan in 3 cases (10–20ml including either 1g vancomycin or clindamycin 1.2g or 100mg tigecycline) into the site was performed. Supplemental systemic antibiotic therapy (oral/intravenous) was instituted based on intraoperative tissue culture and sensitivity. Four patients had infected ankle metalwork, 2 patients infected distal tibial metalwork and 2 had infected external fixators. Metal work was removed in all cases. The mean pre operative CRP was 15.8mg/l (range 1–56mg/l). The mean postoperative CRP at 1 month was 20.5mg/l (range 2–98mg/l). The mean pre op WCC was 7.9×10. 9. (range 4.7–10.5 ×10. 9. ). Mean post op WCC at 1 month was 7.1×10. 9. (range 5.0–9.2×10. 9. ). The organisms cultured included enterobacter, staphylococcus aureus, staphylococcus epidermidis, staphylococcus cohnii, stenotrophomonas, acinetobacter, group B streptococcus, enterococcus and escherichia coli. No additional procedures were required in any case. All surgical wounds went on to heal uneventfully. Infection control and union was achieved both clinically and radiologically in all cases. Our results support the use of a calcium sulphate bio composite with antibiotic as an adjuvant for effective local infection control in cases with implant related bone sepsis. The technique is well tolerated with no systemic or local side effects. We believe that implant removal, debridement and local antibiotic delivery can minimise the need for prolonged systemic antibiotic therapy in such cases