Preoperative computer tomography scans can accurately evaluate tibial bone mineral density for selecting bone fixation in total knee arthroplasty.

Abstract

The mechanical quality of bone at the proximal tibia is an important factor for the success of cementless total knee arthroplasty (TKA). The purpose of this study was to evaluate the relationship between preoperative bone mineral density (BMD) at the tibial resection level (tibial BMD) using computed tomography (CT) and intraoperative cancellous bone durability (ICBD) in TKA. All consecutive cemented and cementless TKAs performed by a single surgeon between April 2024 and October 2024 were evaluated. All patients were examined preoperatively for tibial BMD via CT, hip BMD via dual-energy X-ray absorptiometry. A block of cancellous bone with a diameter of 10 ​mm and a height of 10 ​mm was harvested at the center of the tibia. The fixation method was selected intraoperatively according to the macroscopically evaluated bone quality. Using a pusher tension gauge and a metal measure, the force required to compress the harvested bone from 10 ​mm to 5 ​mm was measured and defined as ICBD. Pearson product-moment correlations were calculated to assess the relationships between tibial and hip BMD and ICBD. A consecutive series of 74 TKAs were included. There were 50 cementless fixations and 24 cemented fixations. Tibial BMD, hip BMD and mean ICBD were significantly greater in the cementless group than in the cemented group (tibial BMD: 70.3 ± 26.2 vs 37.5 ± 14.4, and hip BMD: 87.3 ± 11.8 vs 65.6 ± 10.5, ICBD: 85.6 ± 35.6 vs 49.8 ± 18.1, respectively, P < 0.01). The cut-off value of tibial BMD indicating a cementless prosthesis was 46.4 HA/cm³. There was a very strong correlation between tibial BMD and ICBD (r = 0.88, P < 0.01) and a strong correlation between hip BMD and ICBD(r = 0.62, P < 0.01). This study is the first report to focus on the relationships between CT-based tibial BMD and the actual bone quality of the proximal tibia . Assessment of bone quality via CT is accurate, relatively simple, and potentially useful for determining whether cementless fixation in TKA is indicated. For cementless fixation, 46.4 HA/cm3 and 55.7 N were found as tibial BMD and ICBD cut-off values. Retrospective cohort study, Level Ⅳ.