Distal femoral replacement for selective periprosthetic fractures above a total knee arthroplasty

The management of distal femur periprosthetic fractures in the elderly remains a challenge. The aim of this study was to evaluate the results of distal segmental femur replacement as an alternative to fixation in complex distal femoral periprosthetic fractures in elderly patients.

Twelve patients were included in this prospective study, with a mean age of 78 years (range 68-90 years); incidentally, all were female. Fractures of the distal femur were classified as per Kim et al.'s classification (Clin Orthop Relat Res 446:167-175, 2006); our series included eight patients with type III and four patients with type II periprosthetic fractures. All 12 patients were treated with segmental distal femur replacement (Zimmer Inc., Warsaw, IN, USA). Nine patients required 90 cm and three patients required 130 cm of distal femur segment with a rotating hinge knee prosthesis.

The mean follow up period was 20 months (range 15-28 months), with no major surgical complications reported. The mean duration of hospital stay following surgery was 12 days (range 7-36 days). All patients were mobilising full weight-bearing by day 3. All patients returned to their prior living arrangements. Ten patients returned to their original domicile, with one patient being discharged to a care home requiring minimal ambulatory assistance. The remaining two patients returned to their care homes.

WOMAC scores improved from the pre-injury state with a mean of 49.62 to 72.54 post-surgery (p-value of 0.0001). The Knee Society scores, possible only following surgery, had a mean value of 72. The mean VAS pain score was 1.75 (0 = no pain to 10 = worst pain ever felt). The average range of knee flexion was from 4° to 89° (range -5° to 110°). The mean SF-36 physical functioning score was 45.64 [range 40.70-48.90; standard deviation (SD) -2.62] and the mean SF-36 mental functioning score was 52.94 (range 45.8-57.70; SD -3.38).