Technical innovations in medullary reaming: Reamer design and intramedullary pressure increase

Background: Reaming the medullary cavity leads to an increase in intramedul lary pressure, which can cause local necrosis and lung malfunction after in tramedullary nailing. This investigation concentrates on the effect of ream er design parameters on intramedullary pressure increase. Methods. Pressure measurements were obtained for three newly designed solid reamers and one hollow reamer, The AO/ASIF reamer was used for reference v alues. All reamers were connected with small flexible shafts. The pressures were measured in Plexiglas tubes filled with a mixture of Vaseline and par affin oil. with flow properties at 20 degrees C equivalent to those of bovi ne medullary fat at 36 degrees C, The reaming assemblies were inserted into the tubes using a materials testing machine at a constant speed, In additi on, pressure measurements were made using five pairs of human femora, Results:The highest pressures occurred with the AO/ASIF reamer head (258 +/ - 29 mm Hg, p less than or equal to 0.05). By creating a conical form and e nlarging the flutes, pressures were reduced by up to 37% (164 +/- 13 mm Hg, p less than or equal to 0.05) compared with the AO/ASIF reamer, depending on the depth of the flutes. With a newly designed hollow reamer, pressure w as reduced by 58% (108 +/- 19 mm Hg, p less than or equal to 0.05) compared with the AO/ASIF reamer, Conclusion: The results show that optimizing the design of the reamer head leads to a significant reduction in pressure increase, These results should be taken into consideration when designing new reaming systems in an attem pt to minimize the complication rate for intramedullary nailing.