Abstract
Background:
To evaluate causes and results of revision arthroplasties in unstable total knee arthroplasties
Methods:
We retrospectively reviewed 24 knees that underwent revision arthroplasty for unstable total knee arthroplasty from December 2004 to December 2010. The mean age was 71.0(range, 54–85) years and the average follow-up period was 33.8 months (range, 6–70). The mean interval between the primary TKA and revision TKA was 82.5 months (range, 14–228). We classified the instability and analyzed the treatment according to its cases. Stress radiographs, postoperative component position and joint level were measured. Joint line position was measured using the fibular head as the reference point. Clinical outcomes were assessed using the Hospital for Special Surgery (HSS) score and range of motion. Wilcoxon sign rank test was employed for statistical analysis, and when p-value was over 0.05, it was analyzed as having statistical significances.
Results:
Causes of instability included coronal instability with medial laxity in 13 knees (Fig. 1) and with polyethylene wear in 6 knees, coronal and sagittal instability in 3 knees including post breakage in 1 knee (Fig. 2, Fig. 3), global instability in 1 knee, and flexion instability in 1 knee. Mean preoperative/postoperative varus and valgus angles were 5.8°/3.2°(p = 0.713) and 22.5°/5.6°(p = 0.032). Mean postoperative α, β, γ, δ angle were 5.34°, 89.65°, 2.74°, 6.77°. Mean change of Joint levels were form 14.1 mm to 13.6 mm from fibular head (p = 0.82). The mean HSS score improved from 53.4 to 89.2(p = 0.04). The average range of motion was changed from 123° to 122°(p = 0.82).
Conclusions:
Revision total knee arthroplasty with more constrained prosthesis was a very effective. The solution according to the causes is very important in revision surgery for unstable arthroplasty.
