Minimally invasive plate osteosynthesis in open fractures
Open fractures are associated with significant complications and increased morbidity due to the increased risk of infection, nonunion, malunion, and loss of function. Amputation may even be unavoidable. Open fractures require reconstruction of fractures and soft-tissue coverage, whether by free-tissue flaps, local pedicle flaps, or wound repair. External fixation remains a safe option when used as a primary treatment in cases of open fractures with severe soft-tissue injuries. The circular external fixator, originally introduced by Ilizarov, has been used as definitive management for open fractures for the past two decades. However, the main disadvantages of Ilizarov fixators are prolonged treatment and increased risk of long-term disability. Therefore, staged management of high-energy injuries with the use of temporary external fixation has been successfully advocated especially for the treatment of open proximal tibial fractures. Several authors have demonstrated the benefits of temporary external fixation followed by definitive internal fixation once the soft-tissue envelope has healed sufficiently [ 1– 4]. Monolateral, standard external fixators are relatively inexpensive, easy, and quick to apply.
The timing and selection of definitive treatment methods is controversial when changing the external fixator after the initial treatment. Intramedullary (IM) nailing is an ideal choice for most diaphyseal fractures. However, IM nailing may be problematic when the external fixator has remained in situ for more than two weeks. Pin-track infection may be present and may cause deep infection after nailing. Plating is an alternative choice, however, in the past conventional techniques that required direct exposure with soft-tissue dissection for plate application resulted in serious complications, including wound infection and disturbed bone healing. With the MIPO technique and increased care of soft tissues there is a reduced rate of complications. If MIPO is to be carried out two points need to be considered when applying external fixation in open fractures as the initial treatment. Firstly, the surgeon should not place the pins where the plate will be applied. Secondly, reduction should be achieved and maintained by the external fixator, so that open reduction to correct alignment is not required when the plate is applied as a definitive fixation.
General principles of treatment of open fractures
The treatment goals for open fractures are to prevent infection, obtain bone union, and restore function of the injured limb. Initial assessment of the patient as a whole, evaluation, and the management of any life-threatening injury have priority over treating the open fracture.
A first-generation cephalosporin is recommended for Gustilo-Anderson type I and II open fractures. If the wound is severely contaminated, an aminoglycoside should be added to augment treatment. Tetanus prophylaxis and immunization should be administered to patients who have not been immunized.
Urgent irrigation and debridement of the wound in the operating room is mandatory. For Gustilo-Anderson types II and III injuries, “second-look” operations (wound reevaluation and possible further debridement of necrotic tissue) are recommended 24–48 hours after initial debridement. These may be repeated until a clean surgical wound can be ensured. Skin closure is carried out only if the wound is clean and can be closed without tension. Administration of antibiotics is usually continued for 2 days after the final debridement.
In addition to the management of the soft tissues it is important to stabilize the fracture to improve microcirculation to soft tissues. Wound management, which includes coverage of soft tissues, should be done as soon as possible. There are different types of operations needed to achieve soft-tissue coverage, which vary depending on the size of the soft-tissue defect and the type of tissue loss.
Is there a place for MIPO in the management of open fractures?
When the soft-tissue condition is satisfactory, external fixation should be replaced by internal fixation (either with a plate or IM nail). There are several factors to consider. If there has been pin-track infection, the use of a nail, particularly with reaming, will increase the incidence of intramedullary infection. In cases where the fracture location makes nailing difficult, such as proximal or distal tibial fractures, plating is an option. Generally, in cases of open fractures, MIPO is preferable in most cases when plating is to be used after provisional external fixation is changed to definitive internal fixation.
Indications and contraindications of MIPO in open fractures
Gustilo-Anderson type I or II open injuries which can be treated in a similar way to closed fractures
Periarticular fractures are the main indication for treatment by MIPO (eg, distal femoral fractures, proximal or distal tibial fractures)
Gustilo-Anderson type IIIA or IIIB injuries are also indications for MIPO treatment when the soft-tissue coverage is sufficient in an acute situation after an open fracture or when delayed after debridement
Severely contaminated wound
Open fractures are usually the result of high-energy trauma and there is a significant incidence of associated injuries. The initial evaluation of a patient with an open fracture of a limb should always follow the principles and guidelines of the advanced trauma life support (ATLS) system.
After resuscitation and stabilization of the patient‘s general condition, the open fracture should be debrided in the operating room as soon as possible, preferably within 6 hours of the injury. Reduction of the gross alignment of the limb should be carried out during the initial management, since angulation and displacement could cause further damage from pressure on soft tissues or neurovascular structures. Care should be taken to avoid gross contamination of the intramedullary canal. Correct management of bone and soft tissues is the major determinant of fracture healing and functional restoration of the traumatized extremity.
The soft tissues
A detailed history of the injury, the velocity of the impact, the presence of any crush component, and the location where the injury occurred will help assessment of soft-tissue damage and contamination. The Gustilo-Anderson classification system is universally accepted to grade open fractures. The classification of an open fracture can only be defined precisely after wound exploration and debridement in the operating room.
As microorganisms contaminate most open fractures antibiotics are administered to treat possible infection after wound contamination. To reduce the risk of an infection, early intravenous antibiotics, wound debridement, soft-tissue coverage, and fracture stabilization are required. Tetanus prophylaxis may be necessary, depending on the patient‘s immunization status. The administration of antibiotics before debridement may decrease the infection rate. Cultures of postdebridement specimens and sensitivity testing may help in the selection of the best agents to be used as antibiotic cover for subsequent procedures or in the treatment of an early infection.
Initial surgical management
It is essential to perform early debridement of open fractures. Meticulous excision of nonviable tissue including bone should be performed until the wound is clean.
After debridement it is vital to evaluate the soft-tissue deficit to allow proper planning for definitive wound management. There are several options for treating soft tissue prior to wound closure; these include the placement of antibiotic beads; and recently wound vacuum-assisted closure, a technique that accelerates wound healing before definitive coverage takes place. The goals of early wound coverage are to prevent desiccation of tissue, optimize antibiotic delivery, optimize patient comfort, and close the wound off from the external environment to avoid hospital-acquired infection.
Provisional external fixation is indicated for open fractures associated with gross contamination and severe soft-tissue damage. For managing open intra- or periarticular fractures, spanning external fixation is the treatment of choice at the initial stage, followed by a MIPO procedure when the soft-tissue condition has improved. Limited intraarticular fixation may be performed after debridement if the joint is already exposed. The fixation and the pin of the external fixator should be removed before the application of definitive fixation with MIPO. However, if the state of reduction is good, the external fixator can be used to maintain reduction and be removed after definitive fixation is complete.
Antibiotics used should cover both gram-positive and gram-negative organisms, and should be administered as soon as possible, preferably within 3 hours of the injury occurring. Therapy is recommended for 3 days, however, an additional 3 days of antibiotics administration can be considered, depending on the results of initial cultures. Local therapy with antibiotic-impregnated polymethylmethacrylate cement has been used as an adjunct to systemic antibiotic therapy in treating open fractures with severe contamination and has been shown to reduce the infection rate [1–4].
Timing of MIPO
Definitive surgical reconstruction using MIPO is carried out when the soft tissues have settled. If the soft tissues permit, MIPO can be performed at the time of debridement. Primary MIPO is especially applicable in proximal tibial fractures because the plate is placed on the lateral side where there is good soft-tissue coverage, while the major wound is usually on the medial side. When the wound is contaminated or there is a sign of infection, a delayed MIPO procedure is recommended.
If the soft-tissue problems persist and/or the external fixator has been left in place for 3 weeks or longer, these steps need to be taken:
Remove the external fixator.
Temporarily stabilize the limb in a cast or splint.
Clean the wound and wait until pin track heals.
In some cases debridement of the pin track is necessary to ensure healing. The plate‘s location should be free from any soft-tissue problems. In most cases the bridge plate principle is used.