Factors associated with dynamic knee valgus angle during single-leg forward landing in patients after anterior cruciate ligament reconstruction.

Background: A few studies have reported on how to predict increased dynamic knee valgus angle (KVA), a risk factor for second anterior cruciate ligament (ACL) injury after ACL reconstruction. This study aimed to identify the factors with the potential to predict the KVA during single-leg hop landing.
Methods: Using three-dimensional motion analysis systems, knee motion during a single-leg hop landing task was measured in 22 patients who had undergone ACL reconstruction at 8-10 months postoperatively. The KVA at initial contact (IC) and maximum KVA during the 40-ms period after IC were calculated using the point cluster technique; correlations between the KVA and other factors were assessed. We performed multiple regression analysis to determine whether KVA could be predicted by these parameters.
Results: The KVA was significantly negatively correlated with the static femorotibial angle (FTA; P  < 0.01) and patient height ( P  < 0.01). It was positively correlated with the body mass index ( P  < 0.05). Multiple regression analysis showed that a small FTA could predict the KVA at IC (β: 0.52, 95% confidence interval (CI): 2.24-(-0.42); P  < 0.01). The maximum KVA during the 40-ms period after IC was associated with the FTA (β: 0.46, 95% CI: 2.22-(-0.26); P  = 0.02) and height (β: 0.40, 95% CI: 0.59-(-0.02); P  = 0.04).
Conclusion: At 8-10 months after ACL reconstruction, the KVA was significantly correlated with the FTA, with reduced FTA being associated with an increased dynamic KVA during single-leg hop landing. The measurement of anatomical parameters may aid in predicting the second ACL injury risk after reconstruction.
Competing Interests: The authors have no conflicts of interest relevant to this article.
(© 2020 Asia Pacific Knee, Arthroscopy and Sports Medicine Society. Published by Elsevier (Singapore) Pte Ltd.)