Incidence and Clinical Significance of Heterotopic Ossification After Partial Ray Resection

Leg dystrophic calcification as a consequence of chronic diabetic foot infection: a case report

Foot ulceration and infection is associated with a substantial increase in morbidity and mortality in patients with diabetes. We present a clinical case of recurrent diabetic foot infection with an atypical clinical evolution. A 58-year-old male patient with type 1 diabetes and a history of bilateral Charcot foot neuroarthropathy was followed at our Diabetic Foot Clinic for an unhealed plantar foot ulcer for >1.5 years with recurrent episodes of infection. He was admitted to hospital due to foot ulcer reinfection with sepsis and ipsilateral lower limb cellulitis. The foot infection was found to be associated with an underlying abscess in the anterior compartment of the leg, with a cutaneous fistulous course with extensive alterations of an inflammatory nature. Exudate from the lesion was drained and tissue biopsied, revealing Serratia marcescens and Klebsiella oxytoca with dystrophic calcification (DC). Surgical excision of dystrophic tissue with debridement of the fistulous tracts was performed. The excised material corroborated the presence of fibroadipose connective tissue with marked DC, as well as areas of mixed inflammation compatible with a chronic infectious aetiology. Targeted long-term antibiotic therapy was implemented, for a total of six weeks, with a favourable clinical evolution and complete closure of the lesion at the final follow-up. DC results from calcium deposition in degenerated tissues without evidence of systemic mineral imbalance and is a potential cause of non-healing ulcers. Few cases of DC have been reported in diabetic foot patients and its treatment remains challenging and controversial. A longer follow-up period is necessary to verify the effectiveness of our approach.

Sustained local ionic homeostatic imbalance caused by calcification modulates inflammation to trigger heterotopic ossification

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction. STATEMENT OF SIGNIFICANCE: The ability to regenerate bone in a spatially controlled and reproducible manner is an essential prerequisite for the treatment of large bone defects. As such, understanding the mechanism leading to heterotopic ossification (HO), a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues, would be very useful. Unfortunately, the mechanism(s) behind HO is(are) poorly understood. The present study reviews the literature on HO and based on it, proposes that HO can be caused by a combination of inflammation and calcification. This mechanism helps to better understand current strategies to prevent and treat HO. It also shows new opportunities to improve the treatment of bone defects in orthopedic and dental procedures.