Introduction: Fusion of the knee joint should be the last option for salvage of infected total knee arthroplasty (TKA). Although knee arthrodesis implies lost of function, it is a successful treatment in eradicating the infection and in decreasing pain.
External fixation compression devices have been an excellent method for gaining fusion but, there is no documentation about its ability for obtaining adequate limb alignment with a stable fusion of the knee joint.
Material and Methods: We have retrospectively reviewed the results of knee arthrodesis after infection of TKA using an anteriorly placed unilateral external fixator. In addition, we have assessed patient self-satisfaction.
Postoperative radiographs have been evaluated to digitally measure loss of femoral and tibial bone stock using Engh radiological classification. Moreover, we have quantified tibiofemoral alignment and the section of bony fusion. Fusion of the knee joint was assessed with CT. Patients were interviewed and pain was graded using a Visual Analog Scale (VAS) and self-satisfaction as well as current health status using the 12-item social function survey form (SF12).
Results: From 1992 to 2003, 52 arthrodeses were done for treatment of infected TKA. The average age was 71 years (range, 37–83 years). Type III bone defect according with Engh classification, in femur and/or in tibia, was present in 50% of the patients. The average postoperative tibiofemoral alignment was 1.2° (SD 3.79). The mean time to fusion was 11.26 months (range, 3–30 months). Time to fusion was statistical related with severe bone loss and with the tibiofemoral contact section. The average score according VAS was 1.6 (SD 2.60).
Conclusions: Knee arthrodesis using a monolateral external fixator for infected TKA is an effective method to control infection as well as to obtain knee fusion and pain relief. Severe bone loss, frequently present in infected TKA, was found to be the most relevant factor in achieving tibiofemoral union. The individual clinical result according to SF12 shows a lower quality of life both for physical and mental components compare with general population.
