Nonunion
1. General considerations
There are 2 main treatment strategies available for nonunion of periprosthetic fractures around the knee: revision arthroplasty or revision fixation.
Revision arthroplasty aims to resect the nonunion and replace the nonunion region with a revision arthroplasty prosthesis.
The aim of revision fixation is the same as in standard nonunions, namely overcome the biological and mechanical factors that led to the failure of fracture healing. Because periprosthetic fractures commonly occur in frail elderly patients, revision arthroplasty that removes the need for fracture healing is an attractive option but comes with the additional cost of possible infection.
2. Treatment
Nonunion is uncommon in A-type fractures and rarely a clinical problem. The exception is nonunion of the tibial tubercle, which is usually addressed with revision fixation with or without tibial tubercle transfer to address underlying mechanical issues.
Nonunion in B-type fractures often occurs secondary to an underlying mechanical problem, such as prosthesis loosening, component malalignment, or fracture malreduction. These problems can be addressed with revision arthroplasty procedures. Therefore, this is the most common treatment option.
Nonunion in type C fractures is often similar to nonunion in standard fractures. Therefore, standard revision fixation treatment techniques often apply. However, periprosthetic fractures often occur in frail elderly patients who require reliable postoperative mobilization. Consideration should be given to revision arthroplasty if it is believed that this could provide more reliable mobility. For example, early full weight-bearing after surgery for nonunion of a type C distal femur fracture might be more readily achieved with distal femoral replacement than revision plate fixation.
Nonunion of diaphyseal type C fracture of the femur is particularly amenable to reamed intramedullary fixation. This is true even if the original fracture was treated with plate fixation.
