Clinic of Orthopaedic Surgery, Kantonsspital Baselland Liestal, Liestal, Switzerland.
Foot Ankle Int. 2013 Dec;34(12):1677-82. doi: 10.1177/1071100713505753. Epub 2013 Sep 16.
An unstable valgus ankle with an incompetent medial ligament complex is still treated by many surgeons with isolated tibiotalar (TT) arthrodesis. To date, it is unknown whether rigid fixation of the talus within the ankle mortise sufficiently corrects and stabilizes the hindfoot complex. The purpose of this study was to critically analyze patients with this problem and to assess the underlying causes for their acquired peritalar instability.
This series included 4 male patients (ages 55, 70, 72, and 79 years). Preoperatively, all patients presented with an unstable valgus ankle associated with stage IV adult acquired flatfoot deformity (AAFD), with a valgus talar tilt averaging 12 degrees (ranging from 9 to 14 degrees). All patients had a successful TT fusion, with screws and plates used for fixation. The position of the TT fusion was estimated at the intersection of a line drawn defining the talar shoulders and the longitudinal tibial axis on the anteroposterior weight-bearing radiograph. The hindfoot deformity was measured via the calcaneal offset on the Saltzman view.
All patients had a healed TT fusion with the talus remaining in valgus averaging 4.8 degrees (ranging from 4 to 6 degrees). At the latest follow-up (1.2-18 years), all patients showed a progressive destabilization of the hindfoot complex that resulted in a valgus pronation deformity with flattening of the arch and a highly unstable foot that was not manageable with corrective shoes and braces. Key findings were a floppy hindfoot that turned into extreme valgus misalignment while loading. Radiographically, the calcaneal offset was in valgus misalignment of 16 to 54 mm related to the tibial axis on the Saltzman alignment view. In 2 cases, there was a complete medial dislocation of the talus.
Even with rigid stabilization of the talus in the ankle mortise, peritalar instability may persist and allow calcaneus and navicular subluxation around the talus, which can result in progressive destabilization of the hindfoot complex. In stage IV AAFD, incompetent peritalar ligaments may not be able to withstand the increased mechanical load after TT fusion. Persistent valgus talar tilt after fusion may promote this unfavorable process. Therefore, isolated TT fusion should be performed with caution for treatment of valgus tilted ankles in stage IV AAFD. If this is considered, we recommend that fusion in neutral or even slightly varus talar positions be attempted.
Level IV, retrospective case series.
许多外科医生仍然采用单纯距下关节（TT）融合术来治疗合并内侧韧带复合体不稳定的内翻型踝关节。迄今为止，尚不清楚距骨在踝穴内的刚性固定是否足以矫正和稳定后足复合体。本研究的目的是对具有这种问题的患者进行批判性分析，并评估其获得性距下关节不稳定的根本原因。
本系列包括 4 名男性患者（年龄分别为 55、70、72 和 79 岁）。所有患者术前均表现为不稳定的内翻型踝关节，伴有 IV 期成人获得性平足畸形（AAFD），距骨倾斜平均为 12 度（范围为 9 至 14 度）。所有患者均成功行 TT 融合术，采用螺钉和钢板固定。TT 融合的位置在前后负重 X 线片上定义距骨肩的线和胫骨长轴的交点处估计。距下畸形通过 Saltzman 视图上的跟骨偏移测量。
所有患者的 TT 融合均愈合，距骨平均内翻 4.8 度（范围为 4 至 6 度）。在末次随访（1.2 至 18 年）时，所有患者的后足复合体均出现进行性失稳，导致内翻旋前畸形，足弓变平，足部高度不稳定，矫正鞋和支具无法控制。主要发现是跟骨松弛，在负重时变成严重的内翻对线不良。放射学上，Saltzman 对线视图上跟骨偏移与胫骨轴的偏距为 16 至 54mm。在 2 例中，距骨完全向内侧脱位。
即使距骨在踝穴内得到刚性固定，距下关节仍可能不稳定，允许跟骨和舟骨围绕距骨发生半脱位，从而导致后足复合体进行性失稳。在 IV 期 AAFD 中，不稳定的距下韧带可能无法承受 TT 融合后的增加的机械负荷。融合后持续的距骨倾斜可能会促进这一不利过程。因此，对于 IV 期 AAFD 中内翻型踝关节，TT 融合术应谨慎进行。如果考虑进行 TT 融合术，我们建议尝试将融合位置置于中立位或甚至轻度内翻位。
IV 级，回顾性病例系列。
