Clinical Assessment of Proximal Tibial Morphology at Total Knee Arthroplasty

In light of increasing patient demands and expectations in TKA, a detailed understanding of bone morphology may be the key to optimizing tibial component performance. Current tibial components in TKA fail to reproduce native human geometry. Accurate measurements and ratios of proximal tibia dimensions are important as components move towards more anatomic designs. Methods A consecutive series of TKAs were performed at one center. Proximal tibial measurements were obtained following proximal tibial resection at the time of TKA. These were compared with demographic parameters including height, weight, and gender. Results 145 consecutive primary TKAs (21 bilateral) in 124 patients (85 females, 60 males) were analyzed for this study. Statistical analysis revealed multiple correlations and trends. The tibial dimensions increase linearly in males and females as tibial component size increases. The AP/ML ratio (aspect ratio) of the proximal tibia is fairly constant over the range of bone sizes for both males and females. There is no correlation between aspect ratio and tibial size, nor are there statistical differences between the aspect ratios in males and females. Tibial measurements and component size are positively correlated with both patient height and weight for males and females, although a stronger correlation exists for male patients. On average, the asymmetry between the lateral and medial condyles increases as a function of tibial size. This asymmetry increases more dramatically in males than females. Conclusions These important clinical observations of tibial morphology can be used in designing component lines that more closely resemble native human anatomy, possibly improving performance. Summary Sentence Proximal tibial morphological measurements and ratios provide the design rationale for advanced, conforming components, possibly improving implant positioning, performance and longevity.