Anatomical tibial component is related to more medial tibial stress shielding after total knee arthroplasty in Korean patients

Purpose

This study aimed to investigate stress shielding of anatomical tibial components (ATCs) in comparison to conventional symmetric tibial components (STCs) in Korean patients which may be related to medial tibial bone loss.

Method

78 knees in 59 patients with ATCs (Persona™) and 74 knees in 58 patients with STCs (NexGen LPS-Flex™) were retrospectively reviewed. Radiographic parameters and clinical outcomes in both groups were compared. Logistic regression analysis was performed to identify risk factors for medial tibial bone loss.

Results

Medial tibial bone loss was significantly greater in the ATC group (1.6 ± 1.3 mm) than in the STC group (0.4 ± 0.8 mm) (p < 0.001). The ATC group showed a shorter distance between the distal metal tip and anteromedial cortex and higher invading into the sclerotic bone lesion (ISBL) than the STC group (p = 0.034 and p = 0.044, respectively). Multiple logistic regression analysis suggested ATC, a shorter distance to the anteromedial cortex, and the presence of ISBL as risk factors for medial tibial bone loss. The odds ratios of medial tibial bone loss according to type of prosthesis, distance to anteromedial cortex, and presence of ISBL were 6.25 (range 2.86–13.63, p < 0.001), 0.69 (range 0.51–0.93, p = 0.015), and 3.79 (range 1.56–9.21, p = 0.003), respectively. Notwithstanding, there was no difference in clinical outcomes between the two groups.

Conclusion

In Korean patients, ATCs potentially causes greater medial tibial bone loss due to stress shielding than STCs. The design, however, does not yet appear to affect clinical outcomes at mid-term follow-up.

Level of evidence

Retrospective cohort study, level III.