AUTHOR=Zhou Tianping , Xu Yihong , Zhou Lan , Wang Siya , Wang Shaobai , Xu Weidong 

TITLE=Multi-planar instability, laxity and reduced knee flexion during the support phase of walking are determinants of return to sports

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.1047135

DOI=10.3389/fbioe.2022.1047135

ISSN=2296-4185

ABSTRACT=<p><bold>Background:</bold> After anterior cruciate ligament reconstruction, some patients are not recommended to return to high-level physical activity because they fail to pass return-to-sports tests. The kinematic difference between these patients and those who pass the return-to-sports tests is unclear.</p><p><bold>Methods:</bold> Eighty-two patients who received anatomic single-bundle anterior cruciate ligament (ACL) reconstruction for unilateral ACL injury underwent return-to-sport tests during a hospital visit at a minimum of 9 months (9–11 months) of follow-up. Fifteen patients who passed the return-to-sports tests (RTS group) and fifteen patients who did not (NRTS group) were randomly selected to perform a treadmill walk under dual-fluoroscopic imaging system surveillance for a 6 degrees of freedom kinematic evaluation.</p><p><bold>Results:</bold> Of the 82 patients, 53 passed the return-to-sports tests 9 months after surgery, with a return-to-sports rate of 64.6%. In the stance phase, the NRTS group had a larger anterior tibial translation (1.00 ± 0.03 mm vs. 0.76 ± 0.03 mm, <italic>p</italic> = 0.001), a larger lateral tibial movement (1.61 ± 0.05 mm vs. 0.77 ± 0.05 mm, <italic>p</italic> &lt; 0.001), a larger distal tibial displacement (−3.09 ± 0.05 mm vs. −2.69 ± 0.05 mm, <italic>p</italic> &lt; 0.001), a smaller knee flexion angle (6.72 ± 0.07° vs. 8.34 ± 0.07°, <italic>p</italic> &lt; 0.001), a larger varus angle (−0.40 ± 0.03°VS. -0.01 ± 0.03°, <italic>p</italic> &lt; 0.001) and a larger external rotation angle (1.80 ± 0.05° vs. 1.77 ± 0.05°, <italic>p</italic> &lt; 0.001) than the RTS group. The maximum anterior tibial translation of the NRTS group is also larger than that of the RTS group (3.64 ± 0.42 mm vs. 3.03 ± 0.59 mm, <italic>p</italic> = 0.003).</p><p><bold>Conclusion:</bold> Compared with patients passing RTS tests, those who fail to pass show significant anterior, lateral, and rotational instability; knee laxity; and reduced flexion angle of the knee in the support phase during walking, which may be the possible factors hindering a return to sports.</p>