Treatment of 10-mm-Deep or Greater Uncontained Tibial Bone Defects in Primary Total Knee Reconstruction without Metal Augmentation: Autologous Oblique Structural Peg Bone and Cancellous Chip Bone Grafting

Abstract

Backgroud: In this study, we report satisfactory clinical and radiological outcomes after autologous oblique structural peg bone and cancellous chip bone grafting without metal augmentation, including the use of a metal wedge, block, or additional stem, for patients with ≥ 10-mm-deep uncontained medial proximal tibial bone defects in primary total knee replacement.

Methods: The study group included 40 patients with primary total knee replacement with ≥ 10-mm-deep uncontained tibial bone defects who underwent autologous oblique structural peg bone and cancellous chip bone grafting and were followed-up for at least 1 year. Tibial cutting was performed up to a depth of 10 mm from the articular surface of the lateral tibial condyle, after which the height and area of the remaining bone defect in the medial condyle were measured. The bone defect was treated by making a peg bone and chip bone using excised segments of the tibia and femur. In all cases, the standard tibial stem and full cemented fixation techniques were used without metal augmentation. Preoperative and final follow-up radiologic changes and clinical measures were compared, and prosthesis loosening and bone union were checked radiologically at final follow-up.

Results: The mean depth of the bone defects was 10.9 mm, and the mean percentage of the area occupied by bone defects in the axial plane was 18.4%. The mean mechanical femorotibial angle was corrected from 19.5° varus preoperatively to 0.2° varus postoperatively (p < 0.002). There was no prosthesis loosening, and all cases showed bone union at the 1-year postoperative follow-up.

Conclusions: Even in patients with uncontained tibial bone defects ≥ 10-mm deep in primary total knee replacement, if the defect occupies less than 30% of the cut surface, autologous oblique structural peg bone and cancellous chip bone grafting can be used to achieve satisfactory outcomes with a standard tibial stem and no metal augmentation.

Keywords: Autologous bone graft; Radiography; Tibial bone defect; Total knee arthroplasty.

Fig. 1. A 3-mm burr is used to make a slope medial to the medial tibial defect at 40° angle to the tibial long axis until cancellous bone is observed at the base of the furrow. (A) A curved furrow is made in the anteroposterior direction with a width of 3–4 mm and depth of 5–10 mm according to the size of a bone defect. (B) Then, three pieces of peg bone are inserted to form double cortical support.

Fig. 2. After restoration of a bone defect with chip bone (A), the area of the defect is measured using ImageJ (ver. 1.52; NIH, Bethesda, MD, USA) with photographs of the cut bone surface in the cut plane. The total width of the cut surface (B) and the relative area occupied by the bone defect (C) are measured.

Fig. 3. Long bone anteroposterior views of a 68-year-old female patient. (A) Preoperative view showing 19.7° varus and severe bone defect in the medial tibia condyle of the left knee. (B) Postoperative view showing 1.5° valgus of the left knee at 3-year follow-up.

Fig. 4. (A) After tibial implantation using the full cemented technique, the height of the tibial defect is measured. (B) Knee anteroposterior view of a 68-year-old female patient on the day of surgery.

Fig. 5. Postoperative follow-up radiographs of a 68-year-old female patient. (A) Two months postoperatively. (B) Twelve months postoperatively. (C) Two years postoperatively. (D) Three years postoperatively.