Abstract
Introduction
Various methods to manage medial tibial defects in primary total knee arthroplasty (TKA) have been described. According to Vail TP, metal augmentation is usually indicated for defect depth of >10 mm of the medial tibial plateau. The outcomes of metal augmentation have been described as excellent. Nevertheless, we believe that it is mandatory to preserve as much of the bone as possible for future revision surgeries. Therefore, we performed autologous impaction bone grafting even for large bone defects (defect depth of ≥10 mm) in primary TKA. The objectives of this study are to describe our bone grafting technique in detail and to assess the radiological outcomes of the grafted bone.
Methods
Between 2003 and 2011, 26 TKAs with autologous impaction bone grafting for ≥10 mm medial tibial defects were performed. The preoperative diagnoses were osteoarthritis in 17 knees, rheumatoid arthritis in 2 knees, osteonecrosis of the medial tibial condyle in 6 knees, and Charcot's joint in 1 knee. The average mediolateral width and depth of the medial tibial defects, measured after the horizontal osteotomy of the tibial articular surface, were 17.8 mm (range, 10–25 mm) and 12.0 mm (range, 10–23 mm), respectively. The average patient age at surgery was 73.2 years (range, 56–85 years). The patients were followed up for an average of 55 months (range 27–109 months).
Bone grafting technique: Multiple drill holes (white arrow) were made on the floor of the defect (A) and a morselized cancellous bone was impacted using the grip end of a metal hammer (white asterisk) and firm manual pressure to fill the defect. Thus, the firm impaction prevented bone cement from entering the space between the graft and the tibial host bed. An assistant's index finger (black asterisk) was used as a bank (B). The tibial component was fixed on the grafted bone (white asterisk) with bone cement (C). Internal fixation devices were not required, and stem extension was used in only Charcot's joint (defect depth=23 mm). Aftertreatment was the same as that for the usual TKAs without bone defects.
Results
In terms of clinical outcomes, no patient showed disturbances in walking ability at final follow-up. The average knee flexion angle was 114° (range, 95°–130°). The grafted bone was kept at the grafted area on the radiograms throughout the follow-up period. No absorption or collapse of the grafted bone was observed on the radiograms at the final follow-up. Usually, the grafted bone showed osteosclerotic changes around 2–3 months after TKA. Then, the osteosclerosis became weakened and the bony trabeculae could be detected in the grafted area. Finally, the grafted bone completely incorporated into the host bone in all knees with evidence of bony trabeculae crossing the interface by up to 1 year after surgery. The margin of the grafted area resembled bony cortex in 19 TKAs (73.1%).
Conclusions
Our technique is easy, economic, and reproducible. It is an acceptable alternative to metal augmentation for large medial tibial defects in primary TKA.
