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Objectives: Residents in training are often directed to insert screws using "two-finger tightness" to impart adequate torque but minimize the chance of a screw stripping in bone. This study seeks to quantify and describe two-finger tightness and to assess the variability of its application by residents in training., Methods: Cortical bone was simulated using a polyurethane foam block (30-pcf density) that was prepared with predrilled holes for tightening 3.5 × 14-mm long cortical screws and mounted to a custom-built apparatus on a load cell to capture torque data. Thirty-three residents in training, ranging from the first through fifth years of residency, along with 8 staff members, were directed to tighten 6 screws to two-finger tightness in the test block, and peak torque values were recorded. The participants were blinded to their torque values., Results: Stripping torque (2.73 ± 0.56 N·m) was determined from 36 trials and served as a threshold for failed screw placement. The average torques varied substantially with regard to absolute torque values, thus poorly defining two-finger tightness. Junior residents less consistently reproduced torque compared with other groups (0.29 and 0.32, respectively)., Conclusions: These data quantify absolute values of two-finger tightness but demonstrate considerable variability in absolute torque values, percentage of stripping torque, and ability to consistently reproduce given torque levels. Increased years in training are weakly correlated with reproducibility, but experience does not seem to affect absolute torque levels. These results question the usefulness of two-finger tightness as a teaching tool and highlight the need for improvement in resident motor skill training and development within a teaching curriculum. Torque measuring devices may be a useful simulation tools for this purpose.

Objectives: Significant data exist regarding heat production of twist drills; however, there are little data regarding cannulated drills or Kirschner (K) wires. This study compared the heat produced during bone drilling with twist drills, K wires, and a cannulated drill. It was hypothesized that drilling temperature would increase with tool sizes used in orthopaedic surgery; with twist drills producing the least amount of heat followed by cannulated drills and K wires., Methods: Twist drills (2.0, 2.5, and 3.5 mm), K wires (1.25, 1.6, and 2.0 mm), and a cannulated drill (2.7 mm) were driven into warmed human cadaveric tibia by a battery-powered hand drill. The drill was secured on a servo-controlled linear actuator to provide a constant advancing speed (1 mm/s) during drilling. Two thermocouples were embedded 2 mm from the surface at 0.5 and 1.5 mm from the drill hole margin. Eight tests were performed for each tool., Results: Twist drills exhibited a positive trend between size and heat production. The size effect was less significant with K wires. K wires resulted in significantly (P = 0.008 at 0.5 mm) higher peak temperatures than twist drills of the same size. A 2.7-mm cannulated drill produced more than double the temperature rise of a 2.5-mm twist drill., Conclusions: Twist drills produced the smallest temperature rise among all bit types. Thermal effects should not be a reason for choosing K-wire size. The cannulated drill showed significantly higher temperatures when compared with standard drills, reaching maximal temperatures comparable with K wires.