Stress on the Posteromedial Region of the Proximal Tibia Inc
Anterior cruciate ligament (ACL) injury induces anterior and rotatory instability of the knee. However, the effect of this instability on the stress distribution in the knee joint in living participants is not clear. The aim of this study was to compare the distribution pattern of subchondral bone density across the proximal tibia in the knees with and without ACL injury, and to investigate the correlation between the distribution patterns of the subchondral bone density and the duration of ACL-deficiency.

Radiographic and computed tomography (CT) data pertaining to 20 patients with unilateral ACL injury without combined injury (ACL-deficient group) and 19 nontraumatic subjects (control group) were collected retrospectively.

--HDA% of the posteromedial region was significantly higher in the ACL-deficient group than in the control group.

--In contrast, HDA% of the anteromedial region was significantly lower in the ACL-deficient group than in the control group.

--The logarithm of the time elapsed from ACL injury to CT examination showed a significant correlation with HDA% in the posteromedial region.

Conclusively, in meniscus intact knees, subchondral bone density in the posteromedial region rose significantly following ACL damage and was semi-log associated with the length of ACL deficit. After an ACL injury, the increased stress on the posteromedial region causes a shift in subchondral bone density, justifying early ACL replacement.