33rd Annual Scientific Meeting proceedings

Open fractures represent a major challenge for the orthopaedic surgeon. They can be described as fractures with associated break in the skin that is capable of communicating with the fractured bone and/or its haematoma. Since, by definition, microbial colonization occurs, the amount of soft tissue damage along with vascular compromise will influence the likelihood of bacterial growth and subsequent infection. In order to facilitate treatment decision making, Gustilo and Anderson (1) first proposed in 1976 a classification system based mainly on the severity of soft tissue damage that divided open fractures of the tibia in people into three types:

• Type I: clean fractures, with a wound <1 cm and a simple fracture pattern.
• Type II: clean fractures with a wound >1 cm without significant soft-tissue damage, flaps, or avulsions.
• Type III: any open fractures with multiple fragments, severe contamination, bone loss, significant soft tissue injury, vascular injury, or an associated segmental fracture.

This system was later modified in 1984 (2) due to the heterogeneity of injuries included in type III open fractures:

• Type IIIa: fracture with extensive soft tissue damage but maintains sufficient soft tissue coverage.
• Type IIIb: fracture with periosteal stripping, bone exposure, the need for additional soft tissue coverage, and often massive contamination.
• Type IIIc: open fractures with an associated vascular injury requiring repair.

The guiding principle in the management of open fractures is therefore the prevention of infection. In order to achieve this, guidelines of best practice have been extrapolated from the human traumatology literature (3, 4). Among optimal initial assessment and management of the patient and the wound, stabilization of the fracture plays a key role.

The concept that biomechanical stability is a crucial factor in fracture healing is universally accepted. This is best explained by Perren’s strain theory. In the presence of an unstable fracture configuration, the high strain environment likely exceeds the deformation tolerance of the tissues involved in the healing process. This, in turn, inhibits the sequential differentiation of mesenchymal stem cells into bone, leading to non-union (5). The current understanding is that fracture stability is important not only to achieve fracture healing, but also for prevention and treatment of fracture-related infections (6). The first description of bone healing in the presence of infection was in an experimental study using a sheep model (7). This study demonstrates that bone healing in the presence of infection is possible when a stable implant is present, regardless of whether the construct is absolutely or relatively stable.

There is no consensus on the optimal operative technique for open fractures. The current trend both in human and veterinary traumatology is to consider a biological approach to fracture stabilisation whenever possible through minimally invasive osteosynthesis (MIO). Key elements in this philosophic approach are obtaining a functional reduction of the bony segment (restoration of the length while maintaining axial and torsional alignment) avoiding any additional damage to the blood supply of the bone using indirect reduction techniques, small skin incisions remote to the fracture site and avoidance of the deeper tissue planes at the fracture site (8). The conventional internal fixation typically requires extensive surgical approaches to achieve precise anatomic reduction. This can contribute to further devascularization and bone necrosis, which is likely detrimental in an already impaired environment (9). MIO includes techniques like external skeletal fixation (ESF), minimally invasive plate osteosynthesis (MIPO) and minimally invasive nail osteosynthesis (MINO).

ESF techniques have been recognized as the mainstay for definitive stabilization of open fractures in small animals for years (10), allowing both a MIO and open wound management. It is expected that healing of open fractures is somewhat delayed. The soft tissue envelope is compromised and vascularization reduced. Also, the fracture haematoma, which is an important element for healing initiation (11), is often displaced through the wound or by the common key component to profusely lavage of the fracture site to reduce the microbial burden and decrease the chance of infection. Hence, the strategy for a reliable stabilization is to apply a durable construct that will maintain stability throughout the healing process (12). With this in mind, open fracture healing time may exceed the anticipated life expectancy of an ESF. Also, the current trend in humans is to close the traumatic wound as soon as the qualilty of the wound bed allows a plastic reconstruction, typically within 7 days, and at the same time of definitive fracture stabilization with MIPO or MINO (orthoplastic approach) (12). ESF would still play an important role as temporary stabilization while awaiting the right time for the definitive treatment.

This lecture will focus mainly on reviewing the current evidence based literature in both veterinary and human fields regarding definitive stabilization of open fractures.

References

1. Gustilo RB, Anderson JT. Prevention of infection in the treatment of one thousand and twenty-five open fractures of long bones: retrospective and prospective analysis. J Bone Joint Surg Am. 1976;58-A:453-458.
2. Gustilo RB, Mendoza RM, Williams DN. Problems in the management of type III (severe) open fractures: a new classification of type III open fractures. J Trauma. 1984;24(8):742–746.
3. Halawi MJ, Morwood MP. Acute management of open fractures: An evidence-based review. Orthopaedics 2015 Nov;38(11)
4. Diwan A, Eberlin KR, Smith RM. The principles and practice of open fracture care, 2018. Chinese Journal of Traumatology. 2018;21:187-192
5. Perren SM. Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg Br. 2002;84(8):1093–110
6. Metsemakers WJ, Kuehl R, Moriarty TF, Richards RG, Verhofstad MHJ, Borens O, et al. Infection after fracture fixation: current surgical and microbiological concepts. Injury 2018;49(3):511–22.
7. Rittmann WW, Perren SM. Cortical bone healing after internal fixation and infection: biomechanics and biology: Springer-Verlag; 1975.
8. Maritato KC, Barnhart MD. Minimally Invasive Fracture Repair. Veterinary Clinics of North America: Small Animal Practice 2020; 50 (1)
9. The influence of biomechanical stability on bone healing and fracture-related infection: the legacy of Stephan Perren.
10. Ness MG. Treatment of inherently unstable open or infected fractures by open wound management and external skeletal fixation. J Small Anim Pract. 2006; 47(2):83-8.
11. Grundnes O, Reikeras O. The importance of the hematoma for fracture healing in rats. Acta Orthop Scand. 1993;64:340-342
12. Glyde M and Hosgood G. Managing open fractures: is it time to move beyond external fixators and open wound management? Proceedings 5th World Veterinary Orthopaedic Congress ESVOT-VOS, Barcelona 2018, p. 282.
13. Boriani F et al. Orthoplastic surgical collaboration is required to optimise the treatment of severe limb injuries: a multi-centre, prospective cohort study. Journal of Plastic, Reconstructive & Aesthetic Surgery (2017) 70, 715-722