Stress radiography at 30° of knee flexion is a reliable evaluation tool for high-grade rotatory laxity in complete ACL-injured knees

Abstract

Purpose To evaluate the diagnostic value of stress radiography and determine the cutoff values for high‐grade anterolateral rotatory laxity in complete anterior cruciate ligament (ACL)‐deficient knees at different positions. Methods Forty‐two patients with complete ACL rupture (group 1) and 37 normal subjects (group 2) were prospectively enrolled. The amount of anterior translation in the medial (MM) and lateral (LL) distance compartments and the difference between them (LL‐MM distance) were measured using stress radiography at 30°, 45°, 60°, and 90° positions. The area under the receiver operating characteristic curve (AUC) was assessed for the presence of a high‐grade (grade > 2) pivot shift. Results The MM and LL distances in group 1 were significantly different at 30° and 45° positions (P < 0.05). The AUC of the MM (AUC, 0.903) and LL (AUC, 0.901) distances at the 30° position was significantly higher than that of the other positions (P = 0.000); however, the cutoff values were different to diagnose ACL injury (MM vs. LL, 3.1 mm vs. 5.4 mm). A 2.1‐mm cutoff for the LL‐MM distance showed 78.4% sensitivity and 90.3% specificity for detecting the presence of a high‐grade pivot shift (AUC = 0.905, P = 0.000). Conclusion The cutoff values of stress radiography differed according to anatomical references and knee flexion positions. Stress radiography of a 2.1 mm difference in LL‐MM distance at 30° of knee flexion can be a reliable method for high‐grade rotatory laxity in complete ACL‐injured knees. Level of evidence Level 1, diagnostic study.

The Functional Integrity of the Anterior Cruciate Ligament Can Be Objectively Assessed With the Use of Stress Radiographs: A Systematic Review

“…Stress radiographs were reliable in diagnosing ACL tears, with high sensitivities and specificities. 1,2,5,8,13,14,16,24 Furthermore, this review found 30°of knee flexion optimal for assessing ACL integrity through stress radiography. In addition, standing stress radiography was reliable in diagnosing ACL tears, particularly secondary failures, failures .4 years, and injuries with associated meniscal injuries.…”

“…1 The Telos device was reported to have a sensitivity ranging from 88% to 95% and a specificity ranging from 80.7% to 96%, compared with the KT-1000 arthrometer, which had a sensitivity of 72.1% and specificity of 91.9%. 6,16 Kim et al 13 1.1 further stratified the sensitivities and specificities of the Telos device by comparing medial and lateral compartment ATT values. They reported that measuring the medial compartment had a sensitivity of 94.6% and a specificity of 81.1% while measuring the lateral compartment had a sensitivity of 94.6% and a specificity of 80.7%.…”

“…landmarks used in several other studies, which measured the distance between a line parallel to the tibial cortex and tangent to the posterior contour of the medial tibial condyle and the posterior aspect of the medial femoral condyle. 5,13,16 These anatomic landmarks are demonstratively effective in accurately measuring the extent of ATT in patients with both partial and complete ACL tears. Ideal tibiofemoral flexion angle was another variable assessed in several studies included in this review.…”

Steep posterior lateral tibial slope, bone contusion on lateral compartments and combined medial collateral ligament injury are associated with the increased risk of lateral meniscal tear

“…Preoperative stress radiographs were obtained using a Telos device (Metax, Hungen, Germany) at 250 N [21, 27]. The side‐to‐side differences between the injured and the contra‐lateral uninjured knees were measured using anatomic points of the medial compartment of the knee [21].…”

“…Preoperative stress radiographs were obtained using a Telos device (Metax, Hungen, Germany) at 250 N [21, 27]. The side‐to‐side differences between the injured and the contra‐lateral uninjured knees were measured using anatomic points of the medial compartment of the knee [21]. The mechanical axis alignment was evaluated using standardized full‐length weight‐bearing radiographs, and categorized as positive for valgus alignment and negative for varus alignment (greater or less than 0°).…”