A Guide To Minimally Invasive Fracture Management
- Volume 20 - Issue 8 - August 2007
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As the practice of medicine continues to evolve, new advances are being initiated in the management of lower extremity trauma. These techniques involve a philosophical change regarding surgical approaches as well as technical innovations.
The first change constitutes a philosophical departure in technique from the classical AO principles for open reduction and internal fixation (ORIF). While traditional AO techniques emphasized obtaining absolute anatomic reduction and rigid internal fixation of fractures, this goal was sometimes complicated by a large incisional approach with significant soft tissue stripping.1,2 This process resulted in a devascularization of the osseous fragments, creating an environment that fostered soft tissue slough/breakdown, delayed union, nonunion, deformity and infection.3-5
We know that soft tissue blood supply is crucial for successful osseous consolidation. As proof, Borreli, et al., demonstrated that the proximal and distal tibial metaphysis have an excellent extraosseous blood supply.6 These extraosseous blood vessels supply the outer one-tenth to one-third of the tibial cortex and the intraosseous circulation supplies the remainder. Both are important for osseous consolidation but the extraosseous source is more compromised by traditional open techniques.
The second change is technical in nature with the emergence of locking plate technology and anatomically specific plates. In traditional fixation, what attaches the plate to the bone is the friction between the head of the screw and the plate. One must place the screw bicortically to achieve this friction. This arrangement can allow toggling of the screws in cases of delayed consolidation or premature increases in stress that result in a loss of stability. With locking screws, the head of the screw is threaded and engages the threaded hole in the plate. This arrangement eliminates toggling and enhances stability. All the screws are locked into the plate and help create an “internal-external fixator.”
Bicortical screw purchase is less important. The plate is not compressed to the bone. Therefore, the underlying blood supply is preserved. This has led to the concept of bridge plating in long bone shaft fractures. The plate is secure to the distal and proximal fracture fragments. This leaves any comminuted region unmolested and helps to preserve vascularity. The lag screw is less utilized and callus formation is acceptable.7,8
These changes create a more biologically friendly approach to fracture management. With complex periarticular fractures, one only needs to provide anatomical reconstruction of the articular surfaces. The metaphyseal and shaft fragments do not need to be anatomically aligned as long as the joint itself is properly oriented.
One can undertake articular reconstruction and the delivery of internal fixation either percutaneously or through small incisions. Cannulated screws and the image intensifier are the surgeon’s friends. The fixation only needs to be stable. It does not need to be absolutely rigid. One can utilize the arthroscope on larger joints to assist in the reduction of articular fracture fragments.9
Can One Use Percutaneous Techniques For Metatarsal Fractures?
The question arises as to which fractures one can reasonably treat with percutaneous or minimally invasive techniques. When considering metatarsal fractures, the Jones fracture is a classic example in which surgeons could employ percutaneous fixation. This fracture is essentially nondisplaced so it requires no reduction but only internal fixation.
Using an image intensifier for orientation, the surgeon can drive a guide percutaneously from the fifth metatarsal tuberosity across the fracture and down the shaft. Then deliver a cannulated, partially threaded screw of the appropriate length over the guide pin. The intramedullary screw is usually 4.5 or 5.0 mm in diameter. One can utilize a 4.0 mm screw with smaller metatarsals and a 6.5 mm screw in larger metatarsals.10 The key is to make sure the threads of the screw are beyond the fracture site. This technique preserves the periosteal blood supply, creates an internal bone graft and compresses the fracture.