Purpose: Severe uncontained tibial bone defects occurring during total knee arthroplasty are challenging, and which treatment method is the best remains unknown. In this study, clinical and radiographic outcomes of double metal blocks augmentation were examined.
Methods: Between 2004 and 2012, double metal blocks augmentation was carried out in 17 patients with severe asymmetric uncontained tibial bone defects. The first block was attached to the tibial tray with screws, and then the second block was cemented to the first block. Out of 17 patients, 13 (8 primary, 5 revision) were available for final follow-up at a median of 69 months (range 24-99). For clinical assessment, range of motion and Knee Society score were evaluated preoperatively and annually thereafter. At the final follow-up, Western Ontario and McMaster Universities Osteoarthritis Index, Oxford knee, Short Form-36, Lower extremity functional scale, and Lower extremity activity scale scores were evaluated. Radiographic assessment for radiolucent lines at the block-cement-bone interfaces and signs of failure was performed annually using fluoroscopy and standard radiographs.
Results: Range of motion and Knee Society score were significantly improved post-operatively. Other clinical outcomes were favourable. Radiolucent lines were seen on fluoroscopy in three knees, but no sign of failure, such as loosening, collapse, or instability, was observed at the final follow-up.
Conclusions: Double metal blocks augmentation is a favourable and useful method, which does not cause mechanical failure or protrusion of the prosthetic because of its modularity, to manage severe asymmetric uncontained proximal tibial bone defects >15 mm in total knee arthroplasty.
Level of evidence: Case series, Level IV.
Keywords: Bone defect; Metal block; Tibia; Total knee arthroplasty.