Abstract
In total knee arthroplasty (TKA), it is technically challenging to manage bone defects on the medial tibial plateau associated with severe varus deformity. Treatments for bone defects include cement filling, bone autografts, and metal augments. Suitable options were selected depending on the size of the defects and patient age. Stem extension was added for all the cases to improve initial fixation. We assessed the clinical and radiologic effects on the addition of stem extension to the tibial component in 10 knees with proximal tibial bone defect.
Four knees with bone defects of less than 5 mm were managed by cement filling. For bone defects larger than 5 mm, 3 patients under 65 years old were treated with autologous bone grafts, and 3 patients over 65 years old had metal augmentations.
The mean JOA score improved from 48.3 points preoperatively to 75.7 points postoperatively. The range of motion and femorotibial angle also improved postoperatively. The implanted positions of the femoral and tibial components were maintained on radiographs at the final follow-up. Although localized radiolucent lines were noted in 4 knees (40.0%) on the medial side of tibia, they was no progressive loosening of the bone-cement interface requiring revision surgery.
The use of stem extensions in patients with bone defects is helpful for secure fixation of the tibial component. Long-term study is required to evaluate the stress shielding effect of the long stem on tibial bone loss and implant survival.
