Cullen Aaron B, Curtiss Shane, Lee Mark A
Department of Orthopaedic Surgery, University of California, Davis Medical Center, 4680 Y St, Sacramento, CA 95817, USA.
J Orthop Trauma. 2009 Aug;23(7):507-13. doi: 10.1097/QAI.0b013e3181a25368.
Lateral locked plating for proximal tibial fractures with metaphyseal disruption provides a biomechanically stable and biologically favorable alternative to conventional medial/lateral plate fixation. New polyaxial screw technology incorporates expanding screw bushings, allowing variable angle screw placement, while providing angular stability. We hypothesize that polyaxial locking plates will exhibit comparable stiffness, strength to failure, and resistance to plastic deformation to conventional locking plates in a proximal tibial gap model.
We stabilized extra-articular metaphyseal gap osteotomies in synthetic composite tibiae with dual medial and lateral plating, Less Invasive Stabilization System (LISS) plates, 4.5-mm proximal tibial lateral locking plates with (LP+) and without (LP-) angled screws, and 4.5-mm polyaxial locking plates with (PA+) and without (PA-) angled screws. All were tested with cyclic, ramped, and axial loading to failure.
No plates demonstrated screw failure before plate failure. Dual-plate constructs did not fail. All lateral plates failed at the osteotomy. LP- failed at low load. PA+ was significantly stiffer (165 +/- 17 N/mm) with greater load to failure (711 +/- 23 N) than all other constructs (PA-: 56 +/- 6 N/mm, 617 +/- 33 N; LP+: 137 +/- 23 N/mm, 488 +/- 39 N; LISS: 76 +/- 5 N/mm, 656 +/- 39 N). PA+ had significantly less plastic deformation (12.1 +/- 0.8 mm) than LP+ (13.4 +/- 3.7 mm), but more than PA- (5.8 +/- 1.2 mm) and LISS (3.9 +/- 0.6 mm). PA- did not differ significantly from LISS in any parameter.
This study demonstrates that this unique polyaxial locking plate mechanism, when tested in various constructs, exhibits similar biomechanical performance regarding stiffness, strength to failure, and resistance to plastic deformation when compared with uniaxial locking plates. The polyaxial locking plate with an angled screw was stiffest and had the greatest load to failure. The polyaxial locking plate alone tested similar to the LISS. In addition, the benefit of the angled screw for biomechanical stability is demonstrated.
对于伴有干骺端破坏的胫骨近端骨折，外侧锁定钢板固定提供了一种在生物力学上稳定且生物学特性良好的替代传统内侧/外侧钢板固定的方法。新型多轴螺钉技术采用了可扩张的螺钉衬套，允许可变角度螺钉置入，同时提供角度稳定性。我们假设在胫骨近端间隙模型中，多轴锁定钢板在刚度、破坏强度和抗塑性变形能力方面与传统锁定钢板相当。
我们使用双侧内侧和外侧钢板、微创稳定系统（LISS）钢板、带（LP +）和不带（LP -）成角螺钉的4.5毫米胫骨近端外侧锁定钢板以及带（PA +）和不带（PA -）成角螺钉的4.5毫米多轴锁定钢板来稳定合成复合材料胫骨中的关节外干骺端间隙截骨术。所有样本均进行循环、斜坡和轴向加载直至破坏测试。
在钢板破坏之前，没有钢板出现螺钉破坏。双侧钢板结构未发生破坏。所有外侧钢板均在截骨处发生破坏。LP - 在低负荷下发生破坏。与所有其他结构相比，PA + 显著更硬（165±17 N/mm），破坏负荷更大（711±23 N）（PA -：56±6 N/mm，617±33 N；LP +：137±23 N/mm，488±39 N；LISS：76±5 N/mm，656±39 N）。PA + 的塑性变形（12.1±0.8 mm）明显少于LP +（13.4±3.7 mm），但多于PA -（5.8±1.2 mm）和LISS（3.9±0.6 mm）。PA - 在任何参数上与LISS均无显著差异。
本研究表明，这种独特的多轴锁定钢板机制在各种结构中进行测试时，与单轴锁定钢板相比，在刚度、破坏强度和抗塑性变形能力方面表现出相似的生物力学性能。带成角螺钉的多轴锁定钢板最硬，破坏负荷最大。单独测试的多轴锁定钢板与LISS相似。此外，还证明了成角螺钉对生物力学稳定性的益处。
