Diabetic Calcaneal Osteomyelitis: Outcomes Before and After the Introduction of Bone Graft Substitutes—A Retrospective Cohort Study

Background: Calcaneal osteomyelitis is a severe form of diabetic foot osteomyelitis associated with poor healing, major amputation, and increased mortality. Evidence on the use of bone graft substitutes in this setting remains limited. Methods: We conducted a retrospective single-center cohort study including 103 consecutive patients with diabetic calcaneal osteomyelitis treated at a tertiary diabetic foot center. In total, 29 patients received bone graft substitutes following surgical debridement, while 74 underwent conventional surgical treatment. Outcomes included healing, time to healing, major amputation, and mortality for all-cause. Results: Overall healing rates were similar between the bone graft and control groups (58.6% vs. 54.1%; p = 0.83). However, healing within one year was more frequent in patients treated with bone graft substitutes (65.4% vs. 45.8%). In multivariable analysis, bone graft substitute treatment was independently associated with healing within one year (OR 4.96, 95% CI 1.18–20.79; p = 0.029). Median healing time was significantly shorter in the bone graft group (90 [IQR 60–120] vs. 210 [IQR 150–370] days; p < 0.001), corresponding to a 67% reduction after adjustment. Major amputation rates were low and comparable between groups (10.3% vs. 13.5%; p = 0.75). Observed three-year mortality was lower in the bone graft group (33.3% vs. 54.8%), and bone graft substitute treatment remained independently associated with reduced 3-year mortality (OR 0.29, 95% CI 0.09–0.88; p = 0.028). Conclusions: In diabetic calcaneal osteomyelitis, bone graft substitutes were associated with faster healing, improved 1-year healing outcomes, and lower long-term mortality, while maintaining high limb-salvage rates. These findings suggest that bone graft substitutes may represent a promising adjunct to surgical treatment and warrant confirmation in prospective studies.