Stenquist Derek S, McCaskey Meghan, Diaz Miguel, Munassi Steven D, Ayala Giovanni, Donohue David, Mir Hassan R
Orthopaedic Trauma Service, Tampa General Hospital/Florida Orthopaedic Institute, Tampa, FL; and.
Foundation for Orthopaedic Research and Education (FORE), Tampa, FL.
J Orthop Trauma. 2024 Jan 1;38(1):e4-e8. doi: 10.1097/BOT.0000000000002683.
To determine change in stiffness and horizontal translation of a geriatric extra-articular proximal tibia fracture model after intramedullary nailing with distal (long)-segment blocking screws versus proximal (short)-segment blocking screws.
Unstable extra-articular proximal tibia fractures (OTA/AO 41-A3) were created in 12 geriatric cadaveric tibias. Intramedullary nails were locked with a standard construct (4 proximal screws and 2 distal screws). Specimens were then divided into 2 groups (6 matched pairs per group). Group 1 had a blocking screw placed lateral to the nail in the proximal segment (short segment). Group 2 had a blocking screw placed 1 cm distal to the fracture and medial to the nail (long segment). Specimens were then axially loaded and cycled to failure or cycle completion (50,000 cycles).
Long-segment blocking screws significantly decreased the amount of horizontal translation at the fracture site compared with short-segment screws (0.77 vs. 2.0 mm, P = 0.039). They also resulted in a greater trend towards greater baseline stiffness, (807.32 ± 216.95 N/mm vs. 583.12 ± 130.1 N/mm, P = 0.072). There was no difference in stiffness after cyclic loading or survival through 50,000 cycles between the long-segment and short-segment groups.
Long-segment blocking screws added to an intramedullary nail construct resulted in decreased horizontal translation at the fracture site compared with short-segment screws in this model of a geriatric proximal tibia fracture.
Blocking screws are commonly used to aid in fracture alignment during intramedullary nailing of proximal tibia fractures. Even when not required to attain or maintain alignment, the addition of a blocking screw in either the proximal or the distal (long) segment may help mitigate the "Bell-Clapper Effect" in geriatric patients.
确定在老年胫骨近端关节外骨折模型中，使用远端（长）节段阻挡螺钉与近端（短）节段阻挡螺钉进行髓内钉固定后，骨折部位的刚度和水平位移变化。
在12具老年尸体胫骨上制造不稳定的胫骨近端关节外骨折（OTA/AO 41-A3）。髓内钉采用标准结构锁定（近端4枚螺钉和远端2枚螺钉）。然后将标本分为2组（每组6对匹配样本）。第1组在近端节段（短节段）于髓内钉外侧置入一枚阻挡螺钉。第2组在骨折部位远侧1 cm且髓内钉内侧置入一枚阻挡螺钉（长节段）。然后对标本进行轴向加载并循环至失效或完成50000次循环。
与短节段螺钉相比，长节段阻挡螺钉显著减少了骨折部位的水平位移量（0.77 vs. 2.0 mm，P = 0.039）。它们还导致在基线刚度增加方面有更大的趋势（807.32±216.95 N/mm vs. 583.12±130.1 N/mm，P = 0.072）。长节段组和短节段组在循环加载后的刚度或50000次循环后的存活率方面没有差异。
在此老年胫骨近端骨折模型中，与短节段螺钉相比，在髓内钉结构中添加长节段阻挡螺钉可减少骨折部位的水平位移。
在胫骨近端骨折的髓内钉固定过程中，阻挡螺钉常用于辅助骨折对线。即使在不需要实现或维持对线的情况下，在近端或远端（长）节段添加一枚阻挡螺钉可能有助于减轻老年患者的“钟摆效应”。
