PT  - JOURNAL ARTICLE
AU  - Palmer, Daniel Kyle
AU  - Rios, David
AU  - Patacxil, Wyzscx Merfil
AU  - Williams, Paul A.
AU  - Cheng, Wayne K.
AU  - İnceoğlu, Serkan
TI  - Pullout of a lumbar plate with varying screw lengths
AID  - 10.1016/j.ijsp.2011.12.002
DP  - 2012 Jan 01
TA  - International Journal of Spine Surgery
PG  - 8--12
VI  - 6
4099  - https://www.ijssurgery.com/content/6/8.short
4100  - https://www.ijssurgery.com/content/6/8.full
SO  - Int J Spine Surg2012 Jan 01; 6
AB  - Background Screw length pertains to stability in various orthopedic fixation devices. There is little or no information on the relationship between plate pullout strength and screw length in anterior lumbar interbody fusion (ALIF) plate constructs in the literature. Such a description may prove useful, especially in the treatment of osteoporotic patients where maximizing construct stability is of utmost importance. Our purpose is to describe the influence of screw length on ALIF plate stability in severely and mildly osteoporotic bone foam models.Methods Testing was performed on polyurethane foam blocks with densities of 0.08 g/cm3 and 0.16 g/cm3. Four-screw, single-level ALIF plate constructs were secured to the polyurethane foam blocks by use of sets of self-tapping cancellous bone screws that were 20, 24, 28, 32, and 36 mm in length and 6.0 mm in diameter. Plates were pulled out at 1 mm/min to failure, as defined by consistently decreasing load despite increasing displacement.Results Pullout loads in 0.08-g/cm3 foam for 20-, 24-, 28-, 32-, and 36-mm screws averaged 303, 388, 479, 586, and 708 N, respectively, increasing at a mean of 25.2 N/mm. In 0.16-g/cm3 foam, pullout loads for 20-, 24-, 28-, 32-, and 36-mm screws averaged 1004, 1335, 1569, 1907, and 2162 N, respectively, increasing at a mean of 72.2 N/mm.Conclusions The use of longer screws in ALIF plate installation is expected to increase construct stability. Stabilization from screw length in osteoporotic patients, however, is limited.