In the treatment of synovial pseudarthrosis, all of the synovial-like tissue is removed from between and around the nonunion fragments. If this tissue is not thoroughly removed, the synovial pseudarthrosis may recur. After complete excision of this material, bone autograft is packed in and around the nonunion fragments. Internal fixation is invariably required to secure a synovial pseudarthrosis because the fracture fragments are excessively mobile (which caused the synovial pseudarthrosis to form in the first place).
Another important factor in the treatment of nonunions is the need for compression across the fracture site. In nonunion of the tibia, some surgeons excise a short segment of the intact fibula to permit compression of the tibial fragments. Compression can be achieved either by specific plating technique or with an intramedullary device. The compression, which stimulates bone formation, results in slight shortening of the limb. However, once the nonunion has healed, a heel lift in the shoe easily compensates for the slight leglength discrepancy.
A good example of a fracture with a higher incidence of nonunion (typically atrophic) than most other bones is the scaphoid. The nonunion is traditionally treated with a peg of autograft bone inserted in the medullary cavity of both fragments. With advancements in technology, small fragment compression screws augmented with bone graft have become the typical treatment of choice.
Severe injuries or open fractures in which large segments of bone are lost may create a large bone defect at the nonunion site. The routine method of bone grafting with autogenous bone may not be successful for large defects. A free vascularized bone graft is frequently used to heal this type of nonunion. The midshaft of the fibula with the accompanying arterial supply is typically used as the free vascularized graft, although iliac crest is an alternative donor site. An appropriate segment of the contralateral fibula is excised along with a cuff of muscle and vascular pedicle containing a nutrient artery. The vascularized fibular segment is secured between the nonunion fracture fragments, and the vessels are anastomosed using microsurgical technique. The nonunion containing the vascularized fibular graft must be protected with a cast or brace until a solid bony union develops between the host bone and both ends of the vascularized graft. The diameter of the free vascularized graft from the fibula is obviously smaller than that of the host tibia or femur. However, with time and use, the fibular graft tends to hypertrophy and its diameter may eventually approach that of the host tibia or femur. During this period of bone remodeling, however, the limb must be protected with a brace.
Infected nonunions of any type create a significant and difficult problem to fully treat. Elimination of infection must almost always occur before definitive fixation and healing of a nonunion. Unfortunately, this may require all foreign material (i.e., fixation plates, screws, and rods) to be removed from the infected fracture while the patient undergoes multiple weeks of likely intravenous antibiotic treatment. Patients may need application of an external fixator device to provide some degree of stability while undergoing treatment of infection. After clinical evidence of infection clearance, the nonunion can then undergo definitive fixation by way of the methods just described.
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