Periprosthetic fractures of the distal femur following total knee arthroplasty: even very distal fractures can be successfully treated using internal fixation.

PURPOSE: We treat periprosthetic fracture of the distal femur above total knee arthroplasty using single or double plating and the minimally invasive plate osteosynthesis (MIPO) technique. Here, we report the results of using this operative treatment and our analysis of whether very distally extended fractures can also be successfully treated using internal fixation.

METHODS

We retrospectively reviewed 32 periprosthetic distal femoral fractures. Mean patient age was 73 years and mean follow-up period 25 months. There were 11 (34.4 %) Su type I/II and 21 (65.6 %) type III fractures. All Su type I/II fractures were treated by single plating, whereas 14 of 21 (66.7 %) type III fractures were treated using double plating and the MIPO technique. We defined bony union as the primary endpoint of this study based on callus formation across the fracture site at two or more cortices (1 medial and 1 other) on 3D computed tomography (CT).

RESULTS

Bony union was confirmed in 30 cases (93.8 %) after a mean time to union of 3.7 (range, 3-7) months. Two patients showed nonunion (6.2 %), and one demonstrated delayed union (3.1 %), none of whom complied with our rehabilitation protocol. There was one instance of nonunion among both Su types I/II and III fractures; however, this difference was not significant (p = 0.577).

CONCLUSIONS

Periprosthetic fractures of the distal femur can be successfully healed using internal fixation, either the single- or double-plate MIPO technique, even for very distally extended fractures.