Summary

The positive Pivot Shift test in external rotation suggest the presence of associated lesions in the posterior portion of the medial meniscus, especially at the level of the meniscal ramp, with a greater sensitivity than nuclear MRI.

Abstract

Introduction

Anterior cruciate ligament (ACL) injury is highly prevalent and its incidence is increasing. There is a wide variety of instability patterns, which requires adapting treatment for each particular case. The objective of this research was to evaluate the relationship between the Pivot Shift test in external rotation during the preoperative evaluation and the presence of associated injuries determined during the intraoperative period in patients with ACL injury.

Methods

Prospective observational study in which all patients consecutively operated on for ACL injury between July and August 2024 were analyzed. During the preoperative assessment, the degree of anteroposterior instability (Lachman test) and rotational instability (Pivot Shift test) was determined, both in internal and external rotation. The presence of associated lesions evidenced by preoperative magnetic resonance imaging (MRI) was recorded. Finally, the data were correlated with the findings observed during the intraoperative period. A statistical analysis was performed in order to determine the causal relationship between the presence of Pivot Shift in external rotation and the associated injuries.

Results

The sample was made up of 45 patients, 24 male (53.3%) with an average age of 29.1 and BMI of 27.4. During the preoperative evaluation, 45 patients had a positive Lachman test (100%), 37 had a positive Pivot Shift test in internal rotation (82.2%) and 25 had a positive Pivot Shift test in external rotation (55.6%). Among the patients with positive Pivot Shift in external rotation, 17 (68%) showed meniscal ramp lesion intraoperatively and 5 (20%) another injury to the posterior portion of the medial meniscus. Of the 19 patients with meniscal ramp lesion (42.2%), 17 presented a positive Pivot Shift in external rotation (89.5%) (p<0.01). A statistically significant relationship was observed between the presence of Pivot Shift in external rotation and isolated meniscal ramp lesion (p<0.01), as well as its association with meniscal ramp lesion + injury to the posterior portion of the medial meniscus (p<0.01). The positive Pivot Shift in external rotation presented a sensitivity of 89.5% (95%IC=63.6-98.5%) and specificity of 69.2% (95%IC=48.9-87.4%) to detect isolated meniscal ramp lesion, and a sensitivity of 84.6% (95%IC=59.7-94.8%) and specificity of 84.2% (95%IC=54.4-93.9%) to detect meniscal ramp lesion + injury to the posterior portion of the medial meniscus. Only in 10 of the 19 cases of meniscal ramp lesion (52.6%) was this evident in the preoperative MRI, with a sensitivity of 36.8% (95%IC=18.4-67.1%) and specificity of 88.5% (95%IC=67.6-97.3%).

Conclusion

The positive Pivot Shift test in external rotation suggest the presence of associated lesions in the posterior portion of the medial meniscus, especially at the level of the meniscal ramp, with a greater sensitivity than nuclear MRI. This represents a valuable contribution to understanding the biomechanics of knee instability and developing personalized treatment strategies for each case.