DIAGNOSTIC ACCURACY OF ULTRASOUND IN DETECTING ANTERIOR CRUCIATE LIGAMENT INJURY KEEPING MRI AS GOLD STANDARD

Abstract

Background: Anterior cruciate ligament (ACL) injuries are prevalent in active populations, yet MRI scarcity in low/middle-income countries (LMICs) like Pakistan (≤1 unit/million people) necessitates validation of accessible alternatives like high-resolution ultrasound (HRUS).
Objective: To evaluate HRUS diagnostic accuracy for ACL tears using 1.5T MRI as the gold standard in a Pakistani secondary-care hospital.
Methods: This prospective study enrolled 99 consecutive patients with acute knee trauma at CMH Abbottabad. Standardized HRUS (GE Logiq E10, 10-15MHz transducer) and MRI protocols were applied. Diagnostic accuracy metrics (sensitivity, specificity, PPV, NPV) with 95% confidence intervals were calculated.
Results: The cohort showed male predominance (88.9%) and peak ACL incidence in 18-30-year-olds (58.6%). MRI achieved 100% sensitivity across all injuries (sprains: 67.7%, partial tears: 15.1%, high-grade tears: 17.2%). HRUS detected only 6 high-grade tears (35.3%) all full-thickness ruptures in males while missing all partial tears (0/15) and sprains (0/67), yielding overall sensitivity of 6.1% (95% CI: 2.3–12.9%). Ultrasound failed to identify 93.9% of injuries (93/99 cases), with detection marginally improving >7 days post-injury (50% vs. 20% at <48 hours).
Conclusion: HRUS demonstrated critically low sensitivity, detecting only 6 high-grade tears while MRI detected all injuries (100% sensitivity). Thus, HRUS cannot replace MRI for ACL assessment in LMICs despite cost advantages. Clinical examination (e.g., Lachman test) remains essential for triage