Vascular injury has been reported in up to one third of patients with posterior knee dislocations, which has led to the routine use of arteriograms in the management of these injuries. Recent studies have shown physical examination (PE) is reliable in detecting significant vascular injuries requiring surgery from other mechanisms. We hypothesized that PE would be similarly sufficient to assess popliteal injury in patients with posterior knee dislocations. To test this, we reviewed the records of all 37 patients with 38 such injuries at our institution over the past 5 years. The average age was 29.5 years, and 31 patients (81.5%) had other associated injuries. All dislocations were the result of blunt trauma. Two patients (5.3%) had hard signs (distal ischemia and no pulses) that clearly indicated vascular injury. Total occlusions of the popliteal artery were seen on arteriograms in both cases and these were successfully treated surgically with reversed saphenous vein bypass grafts. The remaining 36 dislocations manifested no hard signs of vascular injury (absent pulses, distal ischemia, active bleeding, bruit/thrill). Nineteen patients (50.0%) had normal vascular examination results, did not receive arteriograms, and had no adverse sequelae, with a mean follow-up of 9.3 months (range 1 day-43 months). Sixteen patients with 17 dislocations (44.7%) underwent arteriography and the findings appeared normal in ten extremities; nine of these extremities had normal pulses and one had a diminished but palpable pulse. A minimal injury (intimal defect, 3; narrowing, 4) was demonstrated in seven extremities, five with normal pulses and two with diminished pulses.(ABSTRACT TRUNCATED AT 250 WORDS)