The Relationship between Anterior Cruciate Ligament injuries and posterior tibial slope.

Abstract

Background: An injury to the anterior cruciate ligament (ACL) is a multifactorial injury and is influenced by intrinsic and extrinsic risk factors. Recently, study of variable anatomy of the proximal tibia has come up as a possible risk factor for an ACL injury. Increased posterior tibial slope (PTS) has been identified as a potential risk factor for anterior cruciate ligament (ACL) injury, but studies which have examined this relationship are inconclusive and sometimes results are contradictory. Methodology: In this study sample size of total 72 patients was included, in which 38 patients had non-contact ACL injury and rest 34 constituted as a control group, who has same demographic characteristics as patients in ACL injury group. This study was conducted in period of April 2017 – Feb 2019 at tertiary care hospital, R.L. Jalappa Hospital, Sduaher, Tamaka, Kolar. All patients included in the study were above 18 years of age and also were willing to participate in the study. Patients with open injury of ipsilateral knee and with previous history of surgery over knee were excluded from the study. The posterior tibial slope was measured from a lateral knee radiograph in all the 72 cases. The data was analyzed for the association between an increased posterior tibial slope and the incidence of ACL injury. Results: In injured group of 38 patients, 15 patients were female and 23 were male. The average age of the patients in this group was 26.7 years (±6.3 years). The control group consisted of 34 patients, in which 24 were men and10 were women. The average age of the control group was 26.2 years (±6.5 years). An ANOVA revealed significant differences in tibial slope angle between the 2 groups. Subjects in the noncontact ACL group had significantly greater tibial slope angles (8.81° ± 2.58°) when compared with control subjects (6.9° ± 2.67°). The trend toward greater tibial slope angles in the noncontact ACL group was also observed when each gender was examined independently; however, the difference was only statistically significant for women between the injury and control groups (8.9° ± 2.6° vs 7.2° ± 2.4°). Conclusion: Our results concluded that, in patients who had non contact ACL injury, had increased posterior tibial slope. But despite of these findings, the clinical significance of an increased tibial slope as an isolated risk factor for ACL injury still remains unanswered. The question also remains as to what degree of increased tibial slope should raise concerns about the increased risk for subsequent injury. Limitations of this study were less number of cases and the study included only non contact ACL injuries. Thus, a study with more number of subjects and also comprising of contact ACL injuries, probably give a better conclusion. Level of evidence: Case-control retrospective study; Level III.