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“With increasing usage within challenging biomechanical constructs, failures of C2 posterior cervical pedicle screws (C2-pCPSs) will occur. The purpose of the study was therefore to investigate the biomechanical characteristics of two revision techniques after the failure of C2-pCPSs.
Twelve human C2
vertebrae were tested in vitro in a biomechanical study to compare two strategies for revision screws after failure of C2-pCPSs. C2 pedicles were instrumented using unicortical 3.5-mm CPS bilaterally (Synapse/Synthes, Switzerland). Insertion accuracy was verified by fluoroscopy. C2 vertebrae were potted and fixed in an electromechanical testing machine with the screw axis coaxial to the pullout direction. Pullout
testing was conducted this website with load and displacement data taken continuously. The peak load to failure was measured in newtons (N) and is reported as the pullout resistance (POR). After pullout, two revision strategies were tested in each vertebra. In Group-1, revision was performed with 4.0-mm C2-pCPSs. In Group-2, revision check details was performed with C2-pedicle bone-plastic combined with the use of a 4-mm C2-pCPSs. For the statistical analysis, the POR between screws was compared using absolute values (N) and the POR of the revision techniques normalized to that of the primary procedures (%).
The POR of primary 3.5-mm CPSs was 1,140.5 +/- A 539.6 N for Group-1 and 1,007.7 +/- A 362.5 N for Group-2; the difference TGF-beta inhibitor was not significant. In the revision setting, the POR in Group-1 was 705.8 +/- A 449.1 N, representing a reduction of 38.1 +/- A 32.9 % compared with that of primary screw fixation. For Group-2, the POR was 875.3 +/- A 367.9 N, representing
a reduction of 13.1 +/- A 23.4 %. A statistical analysis showed a significantly higher POR for Group-2 compared with Group-1 (p = 0.02). Although the statistics showed a significantly reduced POR for both revision strategies compared with primary fixation (p < 0.001/p = 0.001), the loss of POR (in %) in Group-1 was significantly higher compared with the loss in Group-2 (p = 0.04).
Using a larger-diameter screw combined with the application of a pedicle bone-plastic, the POR can be significantly increased compared with the use of only an increased screw diameter.”
“Purpose of review
Inflammation of the allograft, occurring as a consequence of hypoxia and ischemia/reperfusion injury, adversely influences short-term and long-term transplant outcomes. Thus far, imbalance of tissue-protective Treg and tissue-destructive Th17 cells has been confirmed in a number of tissue-inflammatory states, including autoimmune disease. Hence, benefits of tilting Treg-Th17 equilibrium toward dominance of Tregs may promote transplant tolerance.
Recent findings
Adverse graft inflammation creates extreme resistance to the induction of donor-specific tolerance.