Biomechanical evaluation of interlocking lag screw design in intramedullary nailing of unstable pertrochanteric fractures
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Biomechanical evaluation of interlocking lag screw design in intramedullary nailing of unstable pertrochanteric fractures. / Hoffmann, Stefanie; Paetzold, Robert; Stephan, Daniel; Püschel, Klaus; Buehren, Volker; Augat, Peter.
In: J ORTHOP TRAUMA, Vol. 27, No. 9, 01.09.2013, p. 483-90.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Biomechanical evaluation of interlocking lag screw design in intramedullary nailing of unstable pertrochanteric fractures
AU - Hoffmann, Stefanie
AU - Paetzold, Robert
AU - Stephan, Daniel
AU - Püschel, Klaus
AU - Buehren, Volker
AU - Augat, Peter
PY - 2013/9/1
Y1 - 2013/9/1
N2 - OBJECTIVES: Intramedullary nails with special lag screw designs may provide improved mechanical performance and alleviate clinical problems. We hypothesize that the proximal design of trochanteric nails affects mechanical performance.METHODS: Ten pairs of human cadaveric femora were implanted with 2 different short intramedullary nails without (Gamma3) and with an interlocking lag screw (Intertan). An unstable, multifragmentary, pertrochanteric fracture was created. Bones were tested in a cyclic testing protocol with increasing loads until failure simulating 1 leg stance. Stiffness, failure load, cycles to failure, and fracture gap movements were measured.RESULTS: Initially stiffness of the interlocking lag screw nail was almost 40% larger (P = 0.005) compared with the noninterlocking nail. During the test, the difference in stiffness gradually decreased. Failure load (13%, P = 0.02) and cycles to failure (18%, P = 0.02) were larger for the interlocking nail construct. Rotation and varus collapse of the head were initially up to 84% lower (P = 0.013) for the interlocking technique. During the test, the rate of rotational instability gradually increased for both techniques.CONCLUSIONS: The interlocking lag screw design reduced movement of the femoral head and relative movement between fracture fragments. Beyond that the trapezoidal nail design of the Intertan reduced toggling within the trochanteric area and prolonged survival. Although this study showed a decrease in the retention of stability over time, failure did not occur until the equivalent of 2-3 months of reduced physical activity in which healing may have occurred under normal clinical conditions.
AB - OBJECTIVES: Intramedullary nails with special lag screw designs may provide improved mechanical performance and alleviate clinical problems. We hypothesize that the proximal design of trochanteric nails affects mechanical performance.METHODS: Ten pairs of human cadaveric femora were implanted with 2 different short intramedullary nails without (Gamma3) and with an interlocking lag screw (Intertan). An unstable, multifragmentary, pertrochanteric fracture was created. Bones were tested in a cyclic testing protocol with increasing loads until failure simulating 1 leg stance. Stiffness, failure load, cycles to failure, and fracture gap movements were measured.RESULTS: Initially stiffness of the interlocking lag screw nail was almost 40% larger (P = 0.005) compared with the noninterlocking nail. During the test, the difference in stiffness gradually decreased. Failure load (13%, P = 0.02) and cycles to failure (18%, P = 0.02) were larger for the interlocking nail construct. Rotation and varus collapse of the head were initially up to 84% lower (P = 0.013) for the interlocking technique. During the test, the rate of rotational instability gradually increased for both techniques.CONCLUSIONS: The interlocking lag screw design reduced movement of the femoral head and relative movement between fracture fragments. Beyond that the trapezoidal nail design of the Intertan reduced toggling within the trochanteric area and prolonged survival. Although this study showed a decrease in the retention of stability over time, failure did not occur until the equivalent of 2-3 months of reduced physical activity in which healing may have occurred under normal clinical conditions.
KW - Adult
KW - Biomechanical Phenomena
KW - Bone Nails
KW - Bone Screws
KW - Cadaver
KW - Equipment Design
KW - Fracture Fixation, Intramedullary
KW - Hip Fractures
KW - Humans
KW - Male
KW - Materials Testing
KW - Middle Aged
KW - Weight-Bearing
U2 - 10.1097/BOT.0b013e3182a1f54b
DO - 10.1097/BOT.0b013e3182a1f54b
M3 - SCORING: Journal article
C2 - 23860133
VL - 27
SP - 483
EP - 490
JO - J ORTHOP TRAUMA
JF - J ORTHOP TRAUMA
SN - 0890-5339
IS - 9
ER -