Early retropulsion of titanium-threaded cages after posterior lumbar interbody fusion: a report of two cases.

STUDY DESIGN: Two patients had postoperative posterior migration of titanium fusion cages after posterior lumbar interbody fusion. They underwent a repeat posterior procedure and posterior fusion with pedicle screws. OBJECTIVE: To suggest a treatment for posterior migration of titanium-threaded cages causing spinal stenosis after posterior lumbar interbody fusion. SUMMARY OF BACKGROUND DATA: The use of titanium fusion cages in posterior lumbar interbody fusion is gaining popularity as a technique for arthrodesis. The literature contains only a few reports concerning complications associated with their use. METHODS: Two patients had retropulsion of titanium threaded cages, ten days and 2 months after posterior lumbar interbody fusion. The retropulsed cages compressing the dura, caused sudden onset of back pain and radiating pain to the lower extremities. Both patients underwent repeat posterior procedure that included repositioning of the cages and posterior fusion with pedicle screws. RESULTS: Symptoms of back and leg pain subsided after repositioning of the cages and application of the pedicle screws. CONCLUSIONS: A repeat posterior approach and repositioning of the retropulsed titanium fusion cages in addition to posterior fusion with pedicle screws successfully managed this complication.

Thromboxane A2 in postischemic acute compartmental syndrome.

OBJECTIVE: To evaluate whether thromboxane A2 participates in the ischemia-reperfusion injury associated with acute compartmental syndrome (ACS) and if by using a cyclooxygenase inhibitor this can be either reduced or abolished. DESIGN: To assess the role of thromboxane A2 in ACS, a tourniquet was applied for 2 hours to the hind limb of 12 dogs. Group 1 (n = 6) served as controls while group 2 (n = 6) was pretreated with lysine-acetyl-salicylate (Lysoprim). Blood thromboxane B2 levels and intracompartmental pressures were assayed prior to inflation of the tourniquet and at 5 minutes, 90 minutes, and 24, 72, and 144 hours after deflation. RESULTS: Five minutes after deflation, the compartmental pressure increased from 11.2 +/- 2.2 mm Hg to 16.1 +/- 3.3 mm Hg and 17 +/- 2.2 mm Hg (mean +/- SD) in groups 2 and 1, respectively. At 90 minutes and 24 hours, pressures were 17.1 +/- 3.3 mm Hg and 23.2 +/- 3.3 mm Hg (P<.01) and 15.3 +/- 2.6 mm Hg and 25.2 +/- 1.8 mm Hg (mean +/- SD) (P<.001), respectively, in groups 2 and 1. A similar effect, although of a lesser magnitude, was observed in the counterlateral limb. Thromboxane B2 levels increased from a mean (+/- SD) of 46 +/- 5.5 pg/0.1 mL to 132 +/- 7.5 pg/0.1 mL at 90 minutes in group 1, while remaining unchanged in group 2. CONCLUSIONS: Thromboxane A2 plays a major role in the ischemia-reperfusion injury of acute compartmental syndrome. By using a cyclooxygenase inhibitor both the levels of thromboxane and the compartmental pressures can be reduced.