Minimally invasive plate osteosynthesis and bone transport for segmental bone defect
Introduction
The treatment of large segmental bone defects is still a challenging procedure for orthopaedic surgeons. There are different operative possibilities including cancellous bone graft, vascularized fibular transfer, and segmental bone transport, depending on the size of the defect. Bone transport is accepted as the most effective treatment option with low morbidity in the treatment of large-bone defects. The Ilizarov techniques using a ring fixator have been popularized in the treatment of large-bone defects and correcting complex angular deformities. The disadvantages of the ring fixator, however, are pin-track infection, limited joint motion, long-term use of the external fixator, and patient discomfort. The monolateral external fixator is less cumbersome and more comfortable for the patient. Bone transport combining intramedullary nailing and the monolateral external fixator for transport has clear advantages, including improved fixation construction, maintenance of anatomical length, and early removal of the external fixator.
Only recently has MIPO been recognized as a well-accepted technique in fracture treatment especially if combined with the use of a locking compression plate (LCP). Minimally invasive plate osteosynthesis combined with distraction osteogenesis in the treatment of bone defect is also an effective method, which reduces the duration of external fixation, protects against refracture, and allows for early rehabilitation.
Bone transport
Classical bone transport consists of four phases:
Corticotomy and a latent phase, which starts with corticotomy and hyperemia of the corticotomy zone. This usually takes 5–7 days.
Distraction phase of 0.5–1 mm per day (divided into two to three increments of distraction of equal distance). The duration of distraction phase depends on the length of the bone defect.
Consolidation phase, which is the maturation of bone forming in the periosteal tube. This is usually twice as long as the distraction phase in children, and three to four times longer in adults.
Although it may be optional, a bone graft is usually needed to unite the docking site where the transported segment meets the distal segment. Before it is safe to remove the external fixator, the distraction callus as well as docking site should have firm union.
Most of the distraction phase requires the presence of an external distraction device throughout this period, usually utilizing pins or wires. Maintaining the length and alignment during the consolidation phase, which is 2–4 times longer than the distraction phase, can be achieved with a ring fixator, pin fixator, IM nail, or plate and screw. The prolonged use of the external fixator is the most difficult aspect for the patient. The intramedullary device is a more technically demanding insertion into the transport segment and carries more risk of infection. An extramedullary implant consisting of plate and screws provides adequate stability and allows enough space for segmental bone transport.
Principle and concept
In most patients their segmental bone defect has resulted from an open fracture. In these cases an initial radical debridement and temporary fixation with an external fixator is performed. Repeated debridement is carried out until no sign of wound infection can be seen.
The fracture with the segmental bone defect is then stabilized with an LCP bridging the fracture gap, using the submuscular MIPO technique for fixation of proximal and distal fragments. The LCP is fixed to the bone and a space of 0.5–1 cm between the bone and the plate is left to preserve the periosteum. The corticotomy is carried out at least 8–10 cm above the bone defect either by using a drill combined with osteotome or by using the Gigli saw.
The external fixator to be used as a lengthening device is applied over the corticotomy site with at least two pins in each fragment targeting the transport segment toward the docking site. In the femur the distraction device should be fixed on the anterolateral side to prevent the pin from passing through the extensor mechanism. In the tibia, fixation should be carried out on the medial subcutaneous surface.
Distraction begins 5–7 days postoperatively at a rate of 1 mm gained length per day in two increments of 0.5 mm until the transported segment has docked with the other segment. The distraction is continued to compress the bone at the docking site until no further movement of the transport segment is notable. In some cases, if the docking site where the cross-sectional area is not large enough, decortication and bone grafting should be considered. After the procedure the patient is encouraged to move the adjacent joints as tolerated.
The transported segment is fixed to the plate with one or two screws to prevent migration and enhance stabilization of the transport segment. The distraction device is then removed and the patient should start exercising active and passive range of motion of proximal and distal joints. Partial weight bearing should start at 15–20 kg with crutches. The bone defect is then filled with the transport segment and the osteotomy tube will be stabilized through the protection of the plate.
The total time of external fixation includes that taken for corticotomy, distraction period, and compression of the docking site. The consolidation phase does not require the external fixator and its removal allows the patient to carry out range-of-motion exercises. Plate application is used during consolidation which reduces the complications of the prolonged use of the external fixator.
Advantages and disadvantages of plate application
Advantages
Reduces the time the external fixator is in situ
Protects against refracture
No pin-track infection
Less bleeding
Patient comfort, cosmesis
Disadvantages
Technically more demanding
Increases radiation exposure
Further reading
Apivatthakakul T, Arpornchayanon O (2002) Minimally invasive plate osteosynthesis (MIPO) combined with distraction osteogenesis in the treatment of bone defects. A new technique of bone transport: a report of two cases. Injury; 33(5):460–465. Kocaoglu M, Eralp L, Rashid HU, et al (2006) Reconstruction of segmental bone defects due to chronic osteomyelitis with use of an external fixator and an intramedullary nail. J Bone Joint Surg Am; 88(10):2137–2145. Oh CW, Song HR, Roh JY, et al (2008) Bone transport over an intramedullary nail for reconstruction of long bone defects in tibia. Arch Orthop Trauma Surg; 128(8):801–808. Song HR, Oh CW, Mattoo R, et al (2005) Femoral lengthening over an intramedullary nail using the external fixator: risk of infection and knee problems in 22 patients with a follow-up of 2 years or more. Acta Orthop; 76(2):245–252.Case 6: Tibia and fibula, shaft: simple fracture, transverse—42-A2
Case description
A 40-year-old woman sustained osteomyelitis of the tibial shaft after a motor vehicle accident. Initially, the patient sustained an open fracture Gustilo-Anderson type II, which was treated by open reduction and internal fixation. The wound became infected and she developed chronic osteomyelitis. Multiple debridements were carried out to treat the infection including a sequestrectomy, which resulted in a 7 cm bone defect.
Indication for MIPO
A large bone defect can be treated by bone transport. Minimally invasive plate osteosynthesis is combined with bone transport to achieve a shorter time of external fixation and to protect the lengthened segment after removal of the external fixator.
Preoperative planning
A preoperative plan will facilitate the subsequent execution of the surgical procedure. The plan should include a graphic representation of the operative procedure, the surgical approach, the most appropriate implant, and the steps required in its application ( Fig 25-82 ).
Operating room setup
Anesthesia
General or regional anesthesia may be used, depending on the patient‘s condition.
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