AO Foundation, Clavadelerstrasse 8, 7270 Davos Platz, Switzerland.
Foot Ankle Int. 2009 Dec;30(12):1212-8. doi: 10.3113/FAI.2009.1212.
Retrograde intramedullary nailing is an established technique for tibiotalocalcaneal arthrodesis (TTCA). In poor bone stock (osteoporosis, neuroarthropathy), device fixation in the hindfoot remains a problem. Fixed-angle spiral-blade fixation of the nail in the calcaneus could be useful.
In seven matched pairs of human below-knee specimens, bone mineral density (BMD) was determined, and TTCA was performed with an intramedullary nail (Synthes Hindfoot Arthrodesis Nail HAN Expert Nailing System), using a conventional screw plus a fixed-angle spiral blade versus a conventional screw plus a fixed-angle screw, in the calcaneus. The constructs were subjected to quasi-static loading (dorsiflexion/plantarflexion, varus/valgus, rotation) and to cyclic loading to failure. Parameters studied were construct neutral zone (NZ) and range of motion (ROM), and number of cycles to failure.
With dorsiflexion/plantarflexion loading, the screw-plus-spiral-blade constructs had a significantly smaller ROM in the quasi-static test (p = 0.028) and early in the cyclic test (p = 0.02); differences in the other parameters were not significant. There was a significant correlation between BMD and cycles to failure for the two-screw constructs (r = 0.94; p = 0.002) and for the screw-plus-spiral-blade constructs (r = 0.86; p = 0.014).
In TTCA with a HAN Expert Nailing System, the use of a calcaneal spiral blade can further reduce motion within the construct. This may be especially useful in poor bone stock.
Results obtained in this study could be used to guide the operating surgeon's TTCA strategy.
逆行髓内钉是一种成熟的技术，用于跗骨和距骨关节融合术（TTCA）。在骨质较差的情况下（骨质疏松症、神经关节病），后足的器械固定仍然是一个问题。钉在跟骨中的固定角度螺旋刀片固定可能会很有用。
在七对配对的人类小腿标本中，测定了骨密度（BMD），并使用髓内钉（Synthes 跗骨关节融合钉 HAN 专家钉系统）进行 TTCA，在跟骨中使用常规螺钉加固定角度螺旋刀片与常规螺钉加固定角度螺钉。构建体受到准静态加载（背屈/跖屈、内翻/外翻、旋转）和失效循环加载的作用。研究的参数包括构建体中性区（NZ）和运动范围（ROM）以及失效循环次数。
在背屈/跖屈加载下，螺旋刀片加螺钉的构建体在准静态测试（p = 0.028）和早期循环测试（p = 0.02）中的 ROM 明显较小；其他参数的差异不显著。在两种螺钉构建体（r = 0.94；p = 0.002）和螺钉加螺旋刀片构建体（r = 0.86；p = 0.014）中，BMD 与失效循环次数之间存在显著相关性。
在 HAN 专家钉系统的 TTCA 中，使用跟骨螺旋刀片可以进一步减少构建体的运动。在骨质较差的情况下，这可能特别有用。
本研究中获得的结果可用于指导手术医生的 TTCA 策略。
