Purpose: Bone grafting is still requested to fill bone defects in traumatology, or after tumor removal, but also in orthopedic surgery for spine, arthroplasty revisions, and osteotomies. Due to the limitations of autografts and allografts, and the progress of biomaterial research, a large number of nonhuman bony scaffolds have been developed including synthetic calcium phosphates and highly processed xenografts. The most important parameters for bone ingrowth are the macroporosity of the scaffold with the suitable biological autologous cells and factors, optimal osteoinductive, osteointegrative and osteoconductive properties can be achieved. Methods and Results: The important factors regulating these properties are discussed in this paper, which also reports preclinical and clinical results obtained with such bone graft substitutes. Conclusions: Among different bone graft substitutes available, the porosity, the accessibility of pores, the internal surface exposed to the biological components of bone repair, are present in highly processed bovine hydroxyapatites. Compared to autografts, allografts and synthetic substitutes, they associate an initial conductivity, and a long term stability suitable for some orthopedic indications.

Background The coronavirus disease 2019 (COVID-19) pandemic has led to the worldwide implementation of unprecedented public protection measures. On the 17th of March, the French government announced a lockdown of the population for 8 weeks. This monocentric study assessed the impact of this lockdown on the musculoskeletal injuries treated at the emergency department as well as the surgical indications. Methods We carried out a retrospective study in the Emergency Department and the Surgery Department of Nantes University Hospital from 18 February to 11 May 2020. We collected data pertaining to the demographics, the mechanism, the type, the severity, and inter-hospital transfer for musculoskeletal injuries from our institution. We compared the four-week pre-lockdown period and the eight-week lockdown period divided into two four-week periods: early lockdown and late lockdown. Results There was a 52.1% decrease in musculoskeletal injuries among patients presenting to the Emergency Department between the pre-lockdown and the lockdown period (weekly incidence: 415.3 ± 44.2 vs. 198.5 ± 46.0, respectively, p < .001). The number of patients with surgical indications decreased by 33.4% (weekly incidence: 44.3 ± 3.8 vs. 28.5 ± 10.2, p = .048). The policy for inter-hospital transfers to private entities resulted in 64 transfers (29.4%) during the lockdown period. There was an increase in the incidence of surgical high severity trauma (Injury Severity Score > 16) between the pre-lockdown and the early lockdown period (2 (1.1%) vs. 7 (7.2%), respectively, p = .010) as well as between the pre-lockdown and the late lockdown period (2 (1.1%) vs. 10 (8.3%), respectively, p = .004). We observed a significant increase in the weekly emergency department patient admissions between the early and the late lockdown period (161.5 ± 22.9, 235.5 ± 27.7, respectively, p = .028). Conclusion A pronounced decrease in the incidence of musculoskeletal injuries was observed secondary to the lockdown measures, with emergency department patient admissions being halved and surgical indications being reduced by a third. The increase in musculoskeletal injuries during the late confinement period and the higher incidence of severe trauma highlights the importance of maintaining a functional trauma center organization with an inter-hospital transfer policy in case of a COVID-19 second wave lockdown.

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