Extension Malunion of the Femoral Component After Retrograde Nailing: No Sequelae at 6 Years

OBJECTIVES:Supracondylar femoral fracture is a complex complication after total knee arthroplasty (TKA). One potential complication of retrograde locked nailing is malunion in extension of the femoral prosthetic component—produced by an overly posterior nail entry point in the intercondylar notch. The aim of this study was to determine the repercussion of this deformity on the midterm radiological and functional outcomes of TKA. DESIGN:Retrospective review. METHODS:From 2001 to 2006, 30 patients were treated for supracondylar femoral fracture above TKA with a retrograde locked nail. In 7 patients (6 women and 1 man) with a mean age of 78.8 years (range, 74–84 years), more than 10 degrees of hyperextension (mean of 18.5 degrees) of the femoral component on the sagittal plane was observed without any significant misalignment on the coronal plane. Functional outcomes were assessed using the Knee Society Score. RESULTS:After a mean follow-up of 68.5 months (range, 48–111 months), all patientsʼ fractures with a hyperextension of the femoral component had consolidated with no clinical or radiological signs of TKA loosening. These patients presented “good” functional outcomes at final follow-up. CONCLUSIONS:These results should be interpreted with caution. However, isolated hyperextension of the femoral component of a TKA after placing a retrograde nail for a periprosthetic fracture does not seem to significantly affect the functional or radiological outcomes at ∼6-years follow-up. LEVEL OF EVIDENCE:Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.