Debridement, antimicrobial therapy and implant retention (DAIR)

The most important factor for choosing implant retention is a stable fracture with a high likelihood of union. In such cases, a debridement, antimicrobial therapy and implant retention (DAIR) procedure might be feasible. However, this does NOT mean that debridement is somehow easier. An extensive and adequate debridement with tissue sampling is still necessary for infection treatment.

Timing of surgery is still debated for a DAIR procedure. It is generally accepted that DAIR procedures are more effective in early infections, with limited evidence stating the highest success rates before three weeks and suggesting a cut-off between six and 10 weeks after initial osteosynthesis, as known success rates drop to around 67% after that.

Generally, two or more surgeries are needed to achieve healing.

Still needs a description of the step-by-step approach to DAIR

Induced membrane technique/Masquelet technique

The Masquelet technique for fracture-related infections can promote bone healing by creating an induced membrane, which supports the delivery of bone grafts and enhances osteogenesis in the infected bone defect.

This surgical technique has two important phases:

1. The first phase starts with thorough debridement. After the segmental defect is completely excised, an antibiotic-loaded cement spacer of polymethyl methacrylate (PMMA) is created. After placement of the spacer and fixation of the fracture, the wound is closed.
2. In the second phase, after six to eight weeks, the wound is reopened and the segmental defect inspected. The time has allowed the formation of a vascularized membrane or pseudo-periosteum around the spacer. After opening the membrane, the spacer is removed, and autologous bone graft is placed in the defect. The membrane and wound are then closed.

The vascularized membrane and bone graft stimulate the formation of new bone, allowing the fracture to heal. See figure below for additional information.

An advantage of this technique is the relative ‘simplicity’ of the first phase. After debridement and placing the spacer, there is a time window for expert consultation or to refer the patient to a more experienced clinician.

A disadvantage is the necessity of high resource materials like the PMMA and the need for two operations. However, repeated operations are the norm rather than the exception when it comes to FRI treatment.

Vascularized fibula graft

A vascularized fibula graft is a type of autologous, vascularized osseous reconstruction.

In this technique, the patient’s fibula is used to fill the tibial defect left after debridement. The nutrient vessels of the fibula are identified and either spared in case of a pedicled flap (figure below) or transected in case of a free flap. The fibula is also the source of the blood vessels supplying the overlying skin, allowing for the simultaneous harvesting of a skin flap for skin closure. The fibula/skin graft is then placed in the defect and fixated.

The main advantages of this technique:

• It can be applied to large defects up to 30 cm.
• The donor site morbidity is relatively low.
• It provides a strong and solid osseous reconstruction.
• It can be harvested with its overlying skin, which can simultaneously address an overlying soft tissue defect.

However, in cases with significant tibial infection a viable ipsilateral graft may not be available. This may necessitate a free flap, which requires highly specialized equipment (i.e. microscope) and surgical skills, making it less suitable for low-resource settings.

For the description of the technique, this article is recommended to explore.

Click here for a case example of a patient treated with a ipsilateral vascularized fibula graft in Uganda.

Bone shortening (and re-lengthening)

In this technique, the bone defect is addressed by shortening the bone(s). It is a simple technique that can address short segmental defects up to about 2cm.

Avoid too much shortening, particularly in the lower limbs, as this can severely affect gait by inducing leg length discrepancy.

It may be possible to re-lengthen the bone by cutting it at a different level and providing simultaneous distraction, either direct or in a later stage. See figure below.

Bone transport

In case of large bone defects in the femur or tibia, bone transport can be a good treatment option (figure X).

In this technique, two forms of osteogenesis are combined:

• Distraction osteogenesis – the formation of bone between two living bone surfaces slowly separated mechanically.
• Transformation osteogenesis – the conversion of non-osseous interposition material into normal bone by compression or distraction.

A local segment of viable bone will be gradually moved to fill the segmental defect. This prevents loss of limb length and is suitable for large bone defects.

During treatment, the external fixation index can be used to monitor progress.

This technique is extremely time- and resource intensive. Furthermore, it requires the clinician to have a high level of skill, limiting its direct application in low-resource settings.

Adequate debridement remains one the the most challenging and most important elements of the treatment of open fractures and FRI. The presence of a plastic surgeon capable of replacing non-vital tissue with healthy tissue (both for soft tissue and bone) makes the debridement easier and more effective. The best outcomes are probably being achieved when the debridement is performed in a orthoplastic collaboration and the surgeon who does debridement is encouraged to remove all devitalized tissue by a skilled plastic surgeon who can design her/his flap adapted to the size of the defect without compromising. Often a free flap is used in high income settings. However, significant soft tissue defects can be managed with large local flaps (both fasciocutaneus and muscle flaps) in experienced hands with acceptable donor side morbidity, if microsurgical techniques are lacking in resources-limited settings.

We experienced in many settings with limited availability of experienced and skilled plastic surgeons that soft tissue reconstruction is delayed because the wound is 'not ready yet' for soft tissue reconstruction. That means often that a more aggressive debridement is needed, preferably immediately followed with a more challenging local flap or free flap to assure soft tissue coverage. Only when the damage of the debridement cannot be effectively solved with a reconstruction or when the viability of the surrounding tissue is unclear, a more conservative approach is understandable. Because FRI patients confront surgeons with very complex technical challenges, it requires dedicated orthoplastic teamwork with from both specialties superspecialists to achieve the best outcomes. Plastic and orthopedic surgeons should be more specifically trained for these challenges globally.

Why and how to excise dead bone

Apart from the soft tissue debridement, excising dead (necrotic) bone is also essential in fracture-related infection to eliminate infection reservoirs, promote bone healing, and prevent chronic osteomyelitis. Necrotic bone lacks blood supply, making it a breeding ground for bacteria. Because it is non-vascularized, necrotic bone is also resistant to antibiotic treatment.

Removing necrotic bone enhances antibiotic effectiveness and allows healthy bone to regenerate. Additionally, excision facilitates reconstruction with bone grafts or other techniques, improving overall treatment outcomes.

Paprika sign: During excision, be alert for bleeding from small blood vessels in the cortex that occurs when drilling or sawing bone. This is called the ‘paprika sign’, and it indicates vital bone.

After debridement, we recommend to use the new FRI classification to make a personalized treatment plan together with the patient and relatives as explained in the next chapter.

International guidelines are often written in, and for, high-resources settings. In resources-limited settings, they may not always be fully applicable. Only basic methods may be available. Always try to adhere to the international standards, and be aware of suboptimal outcomes when deviating from it. But if there is no option for referral, aim for the most suitable technique available.

For definitive fixation of open fractures, open reduction and internal fixation, is the golden standard. Techniques are well described, for example on the AO Surgery Reference website

For the fixation of the bone, a basic treatment ladder can be a useful tool to choose the optimal treatment for your patient. Starting down it goes from very basic to most advanced options. What is best available treatment for your specific patient in your specific setting? Can better treatment outcome be expected if a treatment higher on the ladder is chosen and if the resources of that step are available (or can be made available when referred)?

The higher up the ladder, the higher the complexity of resources needed:

Always take into account the soft-tissue injury and adapt your fracture management accordingly. Factors such as delayed case presentation, the presence of fracture related infection, and a mal- or non-united fracture influences the strategy and outcome can make the treatment highly complex. Orthopedic trauma surgeons and plastic surgeons working in resources limited settings experience that patient present very late, many days to weeks after the injury. Many of these patient already have a fracture related infection on arrival at the hospital and internal fixation might not be the best option for this patients group.

We provide a brief description of the four fixation technique groups:

Casting

Casting is a technique that provides relative stability to a fracture by limiting mobility and maintaining alignment. It serves as a method of temporary stabilization and pain management, especially during referral or as a bridge to surgery.

It is crucial that wound evaluation and management can be performed effectively. To facilitate this, create a window in the cast for direct visualization and assessment.

^{Circular cast with a window for a midshaft tibial open fracture where advanced fixation options and referral were unavailable and amputation was refused.}

Casting is not intended as a definitive treatment for open fractures. However, it may be the only viable option for fracture fixation in a resource-limited setting where advanced fixation methods are unavailable.

In specific cases, particularly for extra-articular fractures of the tibial shaft, definitive casting can be considered if both the soft tissue condition and fracture configuration permit.

Bone healing

Non-operative management of open fractures

Traction

Traction is used in low-resource settings to treat closed femoral fractures. In cases of open fractures, traction generally serves only as a temporary measure, such as prior to patient transfer or while managing multiple trauma cases.

However, for some open fractures, traction may occasionally be the only viable option. For example, for certain rare proximal femur fractures that are unsuitable for casting or external fixation, or for larger tibial wounds that cannot be cast with a window.

The primary goal should always be to pursue more definitive care.

Various traction techniques are available depending on the fracture location, including:

• Pin traction - Pin traction through the distal femur, proximal tibia, or calcaneus
• Skin traction - Plaster or bandage traction applied to the tibia or foot
• K-wire traction - K-wire traction techniques may be considered for open fractures of the fingers, although in some cases, amputation may be the more appropriate option

Non-operative management of open fractures

^{Proximal tibia pin traction in an intra-articular distal femur fracture.}

Modular external fixation

External fixation in high resources settings is primarily intended for temporary stabilization while awaiting the readiness of the patient and soft tissue condition for definitive internal fixation.

Although regarded as substandard, with certain technical adaptations, external fixation can serve as a practical solution for definitive fracture treatment in resource-limited settings.

In cases with high risk for infection, external fixation may be more suitable than internal fixation.

It offers several advantages, including:

1 Universal applicability across most extremity fracture types

2 Reduced technical demands

3 Lower costs compared to internal fixation, as components can be sterilized and re-used 

When using a modular external fixator as the definitive fixation method, it is crucial to strictly follow the correct procedural steps to prevent premature loosening of pins, as well as fracture-related infection and non-union. 

Applying an external fixator

Definitive fixation with an external fixator

^{Modular external fixation of an open proximal tibia fracture}

Internal Fixation

Internal fixation involves the surgical application of osteosynthesis material directly onto or into the fractured bone. It requires advanced resources and specific surgical expertise. Internal fixation should only be performed if:

1 Immediate wound closure if possible, with either:

• Primary wound closure, or
• The wound is covered with a flap during the same procedure.

AND

2 You have sufficient confidence in soft tissue viability and the wound is not heavily contaminated

If adequately performed, this method provides the necessary alignment and stability, making it suitable for complex fractures, intra-articular injuries, and cases where anatomic reduction is required.

Example - A treatment strategy may be to convert to internal fixation after temporary external fixation when soft tissues have healed, or flap surgery is performed in the same procedure.

Ring fixation

External ring fixators consist of spanned K-wires and sometimes half-pins attached to rings positioned above and below a fracture, forming a highly stable construct to stabilize or correct bone position in a controlled and adjustable way.

External ring fixators are also known as Ilizarov frames or circular frames.

There are many different brands offering ring fixation systems that provide advantages over the normal modular external fixation systems. Modern systems can have a hexapod design that allows for controlled, gradual, and multi-dimensional adjustments in all planes (length, rotation, angulation, translation).

These advanced variations provide the technique for addressing bone defects, limb lengthening and gradual correction of malunions. Computer software-based planning is used to adjust a frame for optimal bone alignment and soft tissue healing.

Although very suitable as spanning frame of a fracture, ring fixators are mostly used as treatment for patients with complex open fractures. Particularly when there is significant bone loss or large soft tissue defects that cannot be covered primarily with optimal fracture reduction.

The basic surgical technique a ring fixator for definitive treatment of open fractures can be highly suitable in resource limited settings.

However, despite their theoretical suitability for low-resource settings, modern ring fixation systems are in practice most often confined to tertiary referral centres where specialised expertise and resources are available.