Summary

This study is the first to have systematically examined changes in passive anterior tibial subluxation (PATS) at multiple time points, confirming the presence of abnormal tibiofemoral relationships in ACL-injured patients despite having gone through successful ACLR. The findings of the present study might serve as a foundation for research on the prognostic value of PATS.

Abstract

Purpose

To track the 24-month longitudinal change in tibiofemoral relationships characterized by passive anterior tibial subluxation (PATS) following anterior cruciate ligament reconstruction (ACLR), and to investigate the association between preoperative and postoperative PATS.

Methods

Fifty-one patients who underwent isolated, anatomic, single-bundle ACLR between March 2021 and February 2022 were enrolled. Clinical and magnetic resonance imaging (MRI) evaluations were performed at baseline (within 3 days preoperatively), 6-, 12-, and 24-month time points to examine the graft integrity and tibiofemoral relationships. Lateral PATS (L-PATS), medial PATS (M-PATS), global PATS (G-PATS), and rotational PATS (R-PATS) were measured on serial MRIs. The repeated-measures one-way analysis of variance was applied to test the longitudinal changes in PATS. Univariate and multivariate linear regression were performed to identify associations between preoperative and postoperative PATS, adjusting for a priori-defined covariates including time from injury to surgery, tibial slopes, meniscal injuries, and anterolateral ligament (ALL) abnormality.

Results

The graft integrity was clinically and radiographically confirmed in all patients by 24-month follow-ups. However, serial MRIs revealed significant increases in L-PATS, M-PATS, and G-PATS (all P<.001) following the primary ACLR. The increases in L-PATS (1.5mm, 95%CI [0.6,2.5], P<.001), M-PATS (1.2mm, 95%CI [0.5,1.9], P<.001), and G-PATS (1.4mm, 95%CI [0.6,2.1], P<.001) from baseline became the most prominent at 12 months and remained stable thereafter. Strong correlations were identified between preoperative and 24-month postoperative values in terms of L-PATS (ß=0.60, P<.001), M-PATS (ß=0.43, P<.001), G-PATS (ß=0.48, P<.001), and R-PATS (ß=0.70, P<.001). ALL abnormality demonstrated associations with increased L-PATS (ß=1.85, P=.008) and G-PATS (ß=1.31, P=.009), while medial meniscal injury demonstrated associations with increased M-PATS (ß=1.12, P=.036) and G-PATS (ß=0.96, P=.048) measured at 24 months postoperatively.

Conclusion

Significant changes in tibiofemoral relationships characterized by increased L-PATS, M-PATS, and G-PATS occurred following ACLR. Postoperative PATS was associated with preoperative PATS, ALL status, and medial meniscal integrity.
Level of Evidence: Level IV, case series.

Purpose

To track the 24-month longitudinal change in tibiofemoral relationships characterized by passive anterior tibial subluxation (PATS) following anterior cruciate ligament reconstruction (ACLR), and to investigate the association between preoperative and postoperative PATS.

Methods

Fifty-one patients who underwent isolated, anatomic, single-bundle ACLR between March 2021 and February 2022 were enrolled. Clinical and magnetic resonance imaging (MRI) evaluations were performed at baseline (within 3 days preoperatively), 6-, 12-, and 24-month time points to examine the graft integrity and tibiofemoral relationships. Lateral PATS (L-PATS), medial PATS (M-PATS), global PATS (G-PATS), and rotational PATS (R-PATS) were measured on serial MRIs. The repeated-measures one-way analysis of variance was applied to test the longitudinal changes in PATS. Univariate and multivariate linear regression were performed to identify associations between preoperative and postoperative PATS, adjusting for a priori-defined covariates including time from injury to surgery, tibial slopes, meniscal injuries, and anterolateral ligament (ALL) abnormality.

Results

The graft integrity was clinically and radiographically confirmed in all patients by 24-month follow-ups. However, serial MRIs revealed significant increases in L-PATS, M-PATS, and G-PATS (all P<.001) following the primary ACLR. The increases in L-PATS (1.5mm, 95%CI [0.6,2.5], P<.001), M-PATS (1.2mm, 95%CI [0.5,1.9], P<.001), and G-PATS (1.4mm, 95%CI [0.6,2.1], P<.001) from baseline became the most prominent at 12 months and remained stable thereafter. Strong correlations were identified between preoperative and 24-month postoperative values in terms of L-PATS (ß=0.60, P<.001), M-PATS (ß=0.43, P<.001), G-PATS (ß=0.48, P<.001), and R-PATS (ß=0.70, P<.001). ALL abnormality demonstrated associations with increased L-PATS (ß=1.85, P=.008) and G-PATS (ß=1.31, P=.009), while medial meniscal injury demonstrated associations with increased M-PATS (ß=1.12, P=.036) and G-PATS (ß=0.96, P=.048) measured at 24 months postoperatively.

Conclusion

Significant changes in tibiofemoral relationships characterized by increased L-PATS, M-PATS, and G-PATS occurred following ACLR. Postoperative PATS was associated with preoperative PATS, ALL status, and medial meniscal integrity.