A cadaver model evaluating femoral intramedullary reaming: a comparison between new reamer design (Pressure Sentinel) and a novel suction/irrigation reamer (RIA).

OBJECTIVE: To compare the intramedullary pressures developed during reaming of cadaveric femurs with the Synthes Reamer/Irrigator/Aspirator (RIA) reamer and the Zimmer Pressure Sentinel (PS) reamer, controlling for the force and speed of reaming. METHOD: Fifteen matched pairs of frozen unpreserved femurs were used in the study. Two pressure transducers and two thermocouples were screwed into holes drilled into the femoral shaft. The femurs were stabilized in the vertical position by mechanically attaching them to a custom jig equipped with a load cell to detect the vertical component of force applied to the reamer. Proximally a linear voltage displacement transducer (LVDT) was attached to the reamer to record the continuous position of the reamer. All femurs were reamed to a diameter 2 mm larger than the narrowest point of the canal. Proximal and distal pressures, proximal and distal temperatures, applied vertical force and displacement were measured continuously throughout the reaming process. Maximum and minimum, and average proximal and distal pressures for each reamer were obtained and compared using paired t-tests. Averages were also calculated and compared in the same manner. A p-value of <0.05 was considered statistically significant. RESULTS: The maximum, minimum and average intramedullary pressures during reaming were significantly lower with the RIA system than the PS reamer. In general, the pressures produced by the RIA system were consistently below atmospheric pressure for the majority of the reaming time. This was not true for the PS system. No appreciable temperature changes were observed during any of the trials. CONCLUSION: The RIA reaming system significantly reduces the intramedullary pressures produced during the reaming process compared to the PS reaming system.