2015 ISAKOS Biennial Congress ePoster #1268

Risk Factors for High Grade Lachman, Pivot-Shift, and Anterior Drawer at ACL Reconstruction

Robert A. Magnussen, MD, MPH, Columbus, OH UNITED STATES
Emily K. Reinke, PhD, Nashville, TN UNITED STATES
Laura J. Huston, MS, Ann Arbor, MI UNITED STATES
Moon Knee Group, MD, Nashville, TN UNITED STATES
Timothy E. Hewett, PhD, Rochester, MN UNITED STATES
Kurt P. Spindler, MD, Garfield Hts, OH UNITED STATES

The Ohio State University, Columbus, OH, USA

FDA Status Cleared

Summary: Chronic ACL tears are assocaited with increased laxity; in acute ACL injuries, generalized ligamentous laxity and medial meniscus tears increase the odds of having high-grade lachman, pivot-shift, and anterior drawer, while ounger age and female sex increase the odds of a high-grade pivot-shift.

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Abstract:

Introduction

Knee laxity in the setting of suspected anterior cruciate ligament (ACL) injury is frequently assessed through physical examination using the Lachman, pivot-shift, and anterior drawer tests. The degree of laxity noted on these examinations, along with the patient’s history and imaging findings, informs the physician’s diagnosis and may influence treatment decisions and prognosis. In addition to injury to the ACL, numerous other factors including patient age, sex, and body mass index (BMI); the chronicity of the ACL injury; generalized ligamentous laxity; and the presence of meniscus tears may influence the degree of laxity detected with these physical examination tests. We hypothesize that younger age, female sex, generalized ligamentous laxity, and associated medial meniscus injuries are associated with high-grade laxity prior to ACL reconstruction.

Methods

From an ongoing prospective cohort study, 2453 patients that underwent primary isolated ACL reconstruction in the absence of medial collateral, lateral collateral, or posterior cruciate injury were identified. Demographic data, physical examination findings under anesthesia at ACL reconstruction, and information regarding additional intra-articular pathology were collected. Patients reported by the operating surgeons as having a Lachman or anterior drawer examination greater than 10mm different from the contralateral side were classified as having a high grade Lachman or anterior drawer respectively. Patients reported by the operating surgeon as having a 3+ pivot-shift were classified as having a high-grade pivot-shift. Multiple logistic regression modeling was used to evaluate whether patient age, sex, and BMI; the chronicity of the ACL injury; generalized ligamentous laxity; and meniscal tears were associated with increased odds of a high grade Lachman, pivot-shift, or anterior drawer.

Results

The chronicity of the tear was a strong predictor of high-grade laxity. Patients with chronic tears (greater than 6 months from injury to surgery) had 2.36 times the odds of having a high grade Lachman (p<0.0005), 2.02 times the odds of having a high grade pivot-shift (p<0.005), and 2.56 times the odds of having a high grade anterior drawer (p<0.005) as patients with acute tears (less than 3 months from injury to surgery). When limiting the analysis to the 1504 patients with acute tears, younger age (10 year odds ratio (OR)=1.30, p=0.008), generalized ligamentous laxity (OR=2.97, p<0.0005), and the presence of medial (OR=1.47, p=0.032) or lateral (OR=1.43, p=0.04) meniscus tears were associated with increased risk of a high-grade Lachman. Similarly, younger age (10 year OR=1.19, p=0.012), female sex (OR=1.39, p=0.014), generalized ligamentous laxity (OR=2.00, p=0001), and the presence of a medial meniscus tear (OR=1.38, p=0.019) were associated with increased risk of a high-grade pivot-shift. Finally, generalized ligamentous laxity (OR=3.82, p<0.0005), and the presence of medial meniscus tear (OR=1.81, p=0.005) were associated with increased risk of a high-grade anterior drawer. BMI did not affect the odds of high-grade laxity.

Conclusion

Increased laxity is associated with more chronic ACL tears. In acute ACL injuries, patients with generalized ligamentous laxity and medial meniscus tears have increased odds of demonstrating high-grade laxity with all three tests, while ounger age and female sex increase the odds of a high-grade pivot-shift.