A positive valgus stress test at about 20 degrees of elbow flexion indicates injury to which ligament?

A positive valgus stress test at about 20 degrees of elbow flexion indicates injury to which ligament?

• A. UCL tear
• B. RCL tear
• C. ACL tear
• D. PCL tear

Answer: (A)

A positive valgus stress test at about 20 degrees of elbow flexion points to injury of the ulnar collateral ligament. This test places valgus (inward) torque on the elbow, stressing the medial side where the ulnar collateral ligament, especially its anterior bundle, provides the primary restraint to valgus stress when the elbow is flexed around 20 degrees. If the ligament is torn or lax, the elbow will show increased medial opening and pain. The lateral collateral ligament would be stressed by varus stress, not valgus, so it wouldn’t be the primary structure implicated here. The ACL and PCL are ligaments of the knee, not the elbow, so they’re not relevant to this exam finding.

A positive valgus stress test at about 20 degrees of elbow flexion points to injury of the ulnar collateral ligament. This test places valgus (inward) torque on the elbow, stressing the medial side where the ulnar collateral ligament, especially its anterior bundle, provides the primary restraint to valgus stress when the elbow is flexed around 20 degrees. If the ligament is torn or lax, the elbow will show increased medial opening and pain.

The lateral collateral ligament would be stressed by varus stress, not valgus, so it wouldn’t be the primary structure implicated here. The ACL and PCL are ligaments of the knee, not the elbow, so they’re not relevant to this exam finding.