Abstract
Background
Bilateral leg alignment should be equal for preventing leg length discrepancy and diminishing limping in walking. The candidates for total knee arthroplasty (TKA) sometimes image bilateral TKA seems to get completely same shape and alignment of legs. The query that bilateral TKA, staged in a day and by one surgeon, has an advantage to reconcile one side alignment and component setting to another side, was investigated.
Materials and methods
This retrospective investigation enrolled 408 knees of 204 patients (74 years old on average) underwent one day TKA and 48 knees of 24 cases (73 years old on average) underwent two days TKA. There were no history of trauma and surgery on both legs and no other obvious features. All components were same (Vanguard PS TKA, Biomet Inc. Warsaw IN). Surgical procedure is single (modified gap technique) with intramedullar rod for the femur and extramedullar system for the tibia without navigation system and patient specific instrumentation (PSI). Postoperative femorotibial angle (FTA), α, β, γ, δ angles were computed and the absolutes of differences between right and left were analyzed. (two sample t test)
Results
Differences of postoperative FTA were 2.4 +/− 1.9 deg in one day, and 3.6 +/− 3.9 deg. in two days (p<0.05). Differences of α angle were 1.7 +/− 1.3 deg. in one day TKA and 2.5 +/− 3.4 deg. in two days TKA (p<0.05), β angle were 1.8 +/− 1.6 deg. and 1.7 +/− 1.4 deg. (ns), γ angle were 3.0 +/− 3.9 deg. and 3.0 +/− 2.6 deg. (ns), δ angle were 2.6 +/− 2.2 deg. and 2.7 +/− 2.5 deg. (ns) respectively.
Discussion
Large volume surgeons purposely do fine adjustment of coronal alignment during operation even if they employ navigation system or PSI. The only landmark for the adjustment of the femur is impalpable femoral head that makes the adjustment difficult although there are several landmarks for the adjustment of the tibia that makes the adjustment reliable. The substitute method for the femoral adjustment is still inaccurate. Several factors such as more range of motion should be considered in sagittal alignment. The differences are wider in sagittal alignment as a result. In summary, bilateral TKA can reconcile one side alignment to other at coronal femoral alignment.
