The Heel Height Test: A Novel Tool for the Detection of Combined Anterior Cruciate Ligament and Fibular Collateral Ligament Tears

Abstract

Purpose: To determine the exact value of side-to-side difference (SSD) in heel height that was associated with combined anterior cruciate ligament (ACL) and fibular collateral ligament (FCL) tears (compared with an isolated ACL tear) and determine the clinical utility of heel height SSD in the assessment of this injury pattern.

Methods: Two patient groups were identified: (1) patients with isolated ACL tears and (2) patients with combined ACL-FCL tears but without additional collateral or cruciate ligament injuries. Determination of the amount of the heel height SSD was determined during the outpatient clinic visit. Receiver operator characteristic curves were used to evaluate the accuracy of diagnostic tests by plotting the true-positive (sensitivity) rate against the false-positive (1-specificity) rate at various thresholds. In addition, magnetic resonance imaging (MRI) reports were reviewed to calculate the sensitivity of MRI for the detection of FCL injury. MRI sensitivity was then compared with the sensitivity of the heel height examination.

Results: One hundred and fifty-eight patients (71 men, 87 women) in the isolated ACL tear patient group and 117 patients (60 men, 57 women) in the combined ACL-FCL tear patient group were reviewed. A 3-cm or greater SSD was found in 13 of the 158 (8.2%) isolated ACL tear patients and 84 of the 117 (72%) ACL-FCL tear patients. The sensitivity, specificity, positive predictive value, and negative predictive value of the heel height test were 72%, 92%, 86%, and 86%, respectively. The area under the receiver operator characteristic curve was found to be 0.876. After review of all preoperative MRI musculoskeletal radiology reports for patients in the ACL-FCL patient group, a sensitivity of 48% was found.

Conclusions: The clinical heel height test resulted in high sensitivity and excellent specificity for the diagnosis of combined ACL-FCL tears compared with the sensitivity and specificity of the MRI detection of FCL injury. The information presented in the current study will improve diagnostic ability through a simple physical examination and avoid missed injuries that are known to compromise surgical outcomes.

Level of evidence: Level III, cross-sectional.