Patients with a diabetic foot infection have a 50-fold increased risk of hospitalisation and 150-fold increased risk of lower-extremity amputation compared with patients with diabetes who have no foot infection – equivalent to 7,000 patients losing a limb every year (Lavery et al, 2006; Pickwell et al, 2015). The cost of management in the NHS is estimated to be between £837 million and £962 million a year (Kerr et al, 2019).
Heel ulcers with calcaneal infection are difficult to treat, with frequent relapses, and the heel is the most likely location for an ulcer that results in lower-extremity amputation (Oliver et al, 2015; Sabater-Martos et al, 2019). Most patients would prefer multiple procedures for limb salvage to amputation and partial calcanectomy is a suitable alternative in these cases (Hoffstad et al, 2015; Gok et al, 2016; Wukich and Raspovic, 2016; Sabater-Martos et al, 2019).
Materials and methods
The authors report a series of four patients who presented with a heel ulcer and calcaneal osteomyelitis. These patients were managed by a multidisciplinary team as per standard protocol. Only patients with satisfactory vascular assessment were taken for surgery. The treatment protocol flow chart is shown in Figure 1.
Cerament G
Cerament G® (Bonesupport AB, Lund, Sweden) is a bio-composite of calcium sulphate and hydroxyapatite with compressive strength equal to cancellous bone. It is injectable, has osteoconductive properties and is completely resorbable. It not only acts as bone filler, but also allows optimum local antibiotic levels (Nilsson et al, 2004; McNally et al, 2015; Ferguson et al, 2017).
Operative technique
The surgery was planned as a single-stage procedure. Patients were operated on in floppy lateral position. A thigh tourniquet was used in all cases. A longitudinal posterior incision was also used, extending the distal and proximal ends of the ulcer. The ulcer was debrided to bleeding healthy tissue margins and the Achilles tendon was sharply reflected off the bone. Multiple soft tissue and bone samples were taken for microbiology.
Based on MRI images (Figure 2), calcaneal excision was planned, with the aim of trying to conserve at least 50% of the bone and the posterior subtalar joint. For local delivery of antibiotic, Cerament G was injected using the Silo technique (Figure 3; Drampalos et al, 2018).
Loose single layer wound closure was achieved in all cases, as the excision of calcaneum de-tensioned the skin in spite of the loss of tissue due to the ulcer. Empirical antibiotic treatment was initially given postoperatively and modified according to the microbiology results from intra-operative samples, for a total of 6 weeks.
Results
Three of the four cases achieved wound healing in an average time of 14.7 weeks (range 12–16 weeks). These wounds always showed delayed primary healing response. Patient four was not compliant with non-weight bearing status and smoking, and eventually had to have a below-knee amputation. The three patients whose wounds healed achieved good postoperative mobility with orthosis in spite of the removal of the insertion of the Achilles tendon during surgery (Table 1).
Discussion
Osteomyelitis of the calcaneum with heel ulcers is a huge challenge to manage, due to coexisting neuropathy, peripheral vascular disease and comorbidities. Partial calcanectomy removes infected bone and de-tensions soft tissue. A recent systematic review of this surgery reports 80% healing rates, with better results occurring with partial rather than total calcanectomies (Yammine et al, 2021).
Local antibiotic delivery systems can deliver high local concentrations of antibiotic without any associated systemic toxicity.
The Cerament G used in our study contains 17.5 mg/ml of gentamicin. Gentamicin elution from Cerament G remains above minimum inhibitory concentration (MIC) for at least 28 days. Local gentamicin concentration levels are 64–150 times higher than the MIC for gentamicin-sensitive pathogens, such as Staphylococcus and Pseudomonas (Colding-Rasmussen et al, 2018).
Multiple studies have shown have excellent results using Cerament as void filler in cases of diabetic foot infection (Armstrong et al, 2001; McNally et al, 2016; Drampalos et al, 2018; Niazi et al, 2019).
Conclusion
Our results also show that using a single stage partial resection of calcaneum with primary closure of wound and local Cerament injection is a viable and useful technique in managing calcaneal osteomyelitis.
The use of Cerament/surgery combination in further larger series of patients can give a clearer picture of the usefulness of this limb-preserving surgery and its role in managing diabetic heel ulcers and calcaneal osteomyelitis in mobile patients with preserved distal vascularity who want to avoid below-knee amputation. n
Acknowledgements
The authors gratefully acknowledge contribution of other members of our diabetic foot multidisciplinary team, namely: Dr Nyi Htwe, Consultant in Diabetes and Endocrinology; Dr Amaar Tarik, Consultant in Diabetes and Endocrinology; Dr Bala Srinivasan, Consultant in Diabetes and Endocrinology; and Murali Subramaniam, Consultant Vascular Surgeon.
