The double-plate fixation technique prevents varus collapse in AO type C3 supra-intercondylar fracture of the distal femur

Abstract

Introduction: Varus collapse followed by osteosynthesis for distal femoral fractures with conventional implants has been well documented but is seldom mentioned in fractures managed with locking plates. The purpose of this study was to assess the incidence of varus collapse after treating complex supra-intercondylar fractures of the distal femur (AO type C3) using a Single Plate (SP) or Double Plate (DP) fixation technique.

Materials and methods: We retrospectively reviewed 357 patients with distal femoral fractures who were treated at our hospital between 2006 and 2017. After excluding cases of infection, malignancy, periprosthetic fracture, revision surgery, pediatric fracture, and extra-articular fracture, 54 patients were included in the study. All demographic data and radiological and clinical outcomes were reviewed and analyzed.

Results: There were 54 patients enrolled into this study with age from 15 to 85 years old (mean 41.6, SD = 19.9), and 32 of them were open fractures (59%). The patients were further divided into either an SP (n = 15) or a DP group (n = 39). Demographics, including age, sex, injury severity score, and open fracture type, were all compatible between the two groups. The overall nonunion rate was 25.9% (n = 14; 6 from the SP and 8 from the DP group; p = 0.175). The varus collapse rate was 9.3% (n = 5; 4 from the SP and 1 from the DP group (p = 0.018).

Conclusions: The varus collapse rate after osteosynthesis with a single lateral locking plate could be as high as 26.7% in AO type C3 fractures of the distal femur, which would be decreased to 2.6% by adding a medial buttress plate. Surgeons should consider DP fixation to avoid varus collapse in severely comminuted complete intra-articular fractures of the distal femur.

Keywords: Distal femur fractures; Double plate; Lateral locking plate; Supra-intercondylar femoral fractures; Varus collapse; Varus malunion.

Fig. 1

The configurations of plates and screws after osteosynthesis with single lateral locking plate (a and b) or double plates (c and d). Note the multiple interfragmental screws were applied in the beginning of the surgery for the reduction and fixation of articular surface. The medial buttress plate was bended to match the curvature of the distal femoral condyle

Fig. 2

The demonstration of varus collapse with malunion after osteosynthesis with lateral locking plate. (a and b) Pre and post-operative anteroposterior plain film of an AO type C3, open type IIIa distal femoral and patellar fracture in a 27-year-old male. c Varus collapse with loosed screws over the femoral shaft at 27 months after the operation. d Malunion with varus deformity at 90 months. The change of LDFA was 11˚. e and f Pre and post-operative anteroposterior plain film of a closed AO type C3 left distal femoral fracture in a 50-year-old male. g and h Varus collapse of the medial femoral condyle with malunion at 14 months after the operation. The change of LDFA was 5˚

Fig. 3

a A 59-year-old male with closed AO type C3 left distal femoral fracture. b Post-operative anteroposterior plain film after osteosynthesis with double plates. c and d The fracture was collapsed and the medial buttress plate was loosed at 21 months. The change of LDFA was 5˚