Abstract
In semi-constrained total knee arthroplasty for severe valgus deformity, there are several possible pitfalls which surgeons have to be aware of. Due to shortened extensor mechanism with laterally shifted patella and contracture of the lateral soft tissues, good results in these cases are more dependent on technique. Certain techniques are also necessary in order to obtain good medial and lateral balance when there is lateral large bone defect on the tibia and/or femoral condyles and attenuation of medial capsular stabilizers.
Here, we describe surgical procedures performed on 3 patients with severe valgus deformity (more than 25 degrees) and discuss the surgical skills which were necessary to obtain proper correction of those deformities.
For the preservation of the extensor mechanism, momentary resection and ref ixation of the tibial tubercle with a flat head screw should be considered. To obtain good ligamentous balance, not only sufficient lateral retinacular release and Z-plasty lengthening of the iliotibial band but also resectioning of the popliteal tendon and posterolateral capsule may be necessary. Bone grafting is essential for a large lateral defect with a depth of more than 5 mm and larger than 25% of the lateral condyle. Advancement or plication of the medial collateral ligament at distal or proximal attachment may have to be performed for severe attenuation of the ligament.
