Duplex Ultrasound Differentiation of Popliteal Artery Spasm Versus True Arterial Injury During Knee Surgery: A Case Report.

Introduction: Vascular compromise during knee surgery is rare but can lead to serious limb-threatening consequences if not identified and managed promptly. Surgeons must rapidly determine whether loss of distal pulses represents reversible compromise, such as compression or spasm, or a true arterial injury requiring urgent repair. Duplex ultrasound provides real-time visualization of arterial anatomy and blood flow patterns, yet its use during orthopedic procedures has been described infrequently. This report presents two intraoperative vascular events during knee surgery that initially appeared similar but required very different management strategies. To our knowledge, this side-by-side comparison emphasizes an uncommon but critical diagnostic role for duplex ultrasound in orthopedic practice. Case Report: The first patient was a 37-year-old man who developed a sudden loss of distal pulses during arthroscopic surgery for severe knee arthrofibrosis after prior ligament reconstruction. Duplex ultrasound showed preserved pulsatile flow in the popliteal artery despite absent signals distally. Further evaluation revealed an expanding hematoma near the posteromedial portal. After hematoma evacuation, distal pulses returned and the patient recovered without vascular intervention.The second patient was a 56-year-old man undergoing corrective osteotomy for longstanding knee instability. He experienced an abrupt loss of distal pulses accompanied by brisk bleeding during wound closure. Duplex ultrasound demonstrated the absence of flow in the popliteal artery. Surgical exploration revealed an intraluminal thrombus and a partial anterior wall laceration of the popliteal artery. Thrombectomy and primary repair restored distal perfusion, and the patient recovered uneventfully after vascular repair. Conclusion: These two cases highlight the importance of distinguishing reversible vascular compromise from true arterial injury during knee surgery. Duplex ultrasound offered a rapid, non-invasive assessment of arterial patency and waveform patterns that helped guide decision-making when distal signals were lost. Incorporating duplex evaluation into the intraoperative workflow may reduce unnecessary exploration, ensure timely vascular consultation, and improve surgical safety. This comparison demonstrates an important and underreported diagnostic application of duplex ultrasound in orthopedic surgery and reinforces its potential value for surgeons managing complex posterior knee exposures or osteotomy procedures.