Review Question - QID 213137

The patient is presenting with a hypertrophic nonunion of the femur below the isthmus, which studies have shown to have a higher union rate when treated with plate augmentation. Retention of the nail allows for full weight-bearing postop.

Hypertrophic nonunion of the femur is the result of fracture site hypermobility with sufficient biology for healing. This is demonstrated with abundant callus formation without bridging trabeculae. Traditionally, this is treated with closed reamed exchange nailing which increased construct stiffness with a larger diameter nail, improved isthmic fit, and extrusion of reaming contents to the nonunion site. However, studies have demonstrated a higher union rate with open plate augmentation, bone grafting, and nail retention. This is due to the ability to correct nonunion site deformity, provide added compression at the nonunion site, and increase fracture site biology with bone graft.

Lynch et al. reviewed the literature regarding the treatment options for femoral nonunions. The literature suggests high union rates when hypertrophic nonunions are treated with exchanged reamed nailing. However, the use of augmentative plate fixation allows for further deformity correction. The proposed mechanism by which exchange reamed nailing is increased construct stiffness with a large diameter nail, usually by 1-2 mm, increased isthmic fit, and autogenous bone graft extrusion into the nonunion site.

Somford et al. performed a systematic review of the surgical treatment of femoral nonunions. Results demonstrate that exchange nailing provides a 73% union rate compared to plate augmentation of 96%. They speculated that there were increased indications for exchange nailing for oligotrophic nonunions in many of the included studies, which may have reduced the union rate. Further, plate augmentation does allow for deformity correction, which can further improve the union rate.

Figures A and B are the AP and lateral radiographs of the femur with hypertrophic nonunion as suggested with the abundant callus formation and broken distal interlock screws. Illustration A and B are the AP and lateral radiographs of the distal femur subsequent plate augmentation and fracture healing.

Incorrect Answers:
Answer 1: Compression plating and bone grafting provide deformity correction across the nonunion site and added biology, but there is loss of weight-bearing benefits with nail removal.
Answer 2: Closed reamed exchange nailing can provide healing of the nonunion by increasing the nail diameter and improving the isthmic fit, but studies have shown a lower union rate in subisthmic femoral nonunions compared to augmentation plating.
Answer 3: Nail dynamization provides the benefit of weight-bearing forces across the nonunion site to enhance the differentiation of osteoblasts and promote fracture healing. In hypertrophic nonunions, fracture site stability is the cause of nonunion rather than the lack of fracture site biology.
Answer 5: Electrical bone stimulators do not provide the added fracture stability that is required to address hypertrophic nonunion.