Ankle Arthrodesis Using Ring External Fixation - Orthofix.com

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mistake is to attach the proximal ring with the bump behind the calf to suspend the leg and no regard for where the calf will be once the bump is removed. If not assessed proactively, the ring will impinge on the calf, necessitating removal of the ring and potential repositioning of thin wires/half pins (Fig. 2). 2. Allow adequate room between the posterior heel and the foot frame. This space does not need to be more than 1.5 cm, as virtually no swelling occurs directly posteriorly at the calcaneus, irrespective of how extensive the surgery is. However, with direct contact of the foot frame to the calcaneus, the external fixator potentially may need to be disassembled and remounted in its entirety (Fig. 8). 3. Be sure the foot is plantar to the foot frame. The plantar foot pad is thicker than it appears, and if the foot frame is positioned too low, it will not be possible to pass the thin wires through the bones of the foot, only the plantar soft tissues. Poor foot frame positioning may again necessitate disassembly of a major portion of the entire construct (Fig. 9). FIGURE 13. The thin wires in the foot are tensioned. Special Focus: Ankle Arthrodesis Using Ring External Fixation FIGURE 12. The calcaneus is stabilized with 2 oblique thin wires. Applying a Prebuilt External Fixator We do not suggest that a prebuilt external fixator is the favored method for ankle arthrodesis using external fixation, but particularly for the surgeon inexperienced with traditional techniques of external fixation, this method may facilitate the procedure. After satisfactory joint preparation, this sequence of steps could be considered. 1. Provisional pin fixation of the arthrodesis site. 2. Intraoperative fluoroscopy to confirm satisfactory position of the tibiotalar arthrodesis site (Figs. 5A, B). 3. Support under the calf (Fig. 2). 4. Positioning of the prebuilt external fixator (Fig. 2). 5. Position the foot frame portion symmetrically about the foot, avoiding contact between the posterior heel and the foot frame (Fig. 10). 6. Next, thin wires and half pins are added to the construct. For ankle arthrodesis, thin wires are smooth, and there is no need to use olive wires. Both thin wires and half pins should be inserted without tensioning the skin. Cold water or saline irrigation or a moist sponge to gently hold the thin wire should be used to cool the wire during insertion. Once the thin wire has exited the opposite cortex, a mallet should be used to complete the insertion. Half pin insertion requires a small stab incision; thin wires can be placed directly through the skin without an incision. 7. Suspend the foot frame from a single wire or 2 forefoot wires (Fig. 11). Traditional positioning of forefoot wires is 1 wire through the first and second metatarsals and the second wire through the fifth through the third metatarsals. This orientation is safe and stable, but necessitates that the wires extend above and below the frame, which may make weightbearing more difficult. Alternatively, a single forefoot wire can be placed from the fifth metatarsal to the first. This wire is usually placed obliquely to the foot FIGURE 14. Proximal ring fixation, in this case, using half pins. Volume 5, Issue 3 155 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
FIGURE 15. A and B, A supplemental half pin in the calcaneus is optional. frame and often needs to be connected off the medial side using a post (extended connector) to avoid excessive plantar flexion of the first ray. 8. Two oblique calcaneal wires are placed (Fig. 12). 9. A fourth thin wire is placed in the midfoot/forefoot. 10. The foot wires are tensioned. If there is an open foot frame construct (open distally), then the forefoot wires need to be tensioned before the calcaneal wires to ensure that tension is maintained in all foot wires (if the calcaneal wires are tensioned before the forefoot wires are tensioned, the calcaneal wires may lose tension, depending on the inherent stiffness of the foot frame) (Fig. 13). 11. With the foot frame securely applied to the foot, the proximal ring block is secured to the tibia. Although provisional fixation remains across the tibiotalar joint, subtle adjustments are still possible (ie, slightly greater dorsiflexion or a shift in rotation can be accomplished). The proper proximal ring position can be maintained with a transverse thin wire that is tensioned. Proximal ring fixation can be performed solely with the use of thin wires, as originally described, but half pins are also an option (Fig. 14). Many different combinations of pins are possible. Generally, when a single tibial ring is used, a clamp that supports 2 half pins in the medial face of the tibia is attached to the superior portion of the the ring, and a clamp that supports 1 additional pin in the anterior tibia is suspended from the inferior portion. When using 2 proximal rings, at least 1 half pin is attached to each ring into the medial face of the tibia, and at least 1 additional pin is clamped to either ring in another plane. 12. Consideration may be given to a supplemental half pin placed posterior to anterior in the calcaneus and attached to the foot frame (Figs. 15A, B). 13. With the thin wires properly tensioned and the half pins adequately secured, compression can now be applied across the tibiotalar arthrodesis site. In a patient with a prior subtalar fusion, compression FIGURE 16. A and B, Talar wires are placed from an intermediate ring not only to provide greater support but to protect the subtalar joint during tibiotalar compression. 156 Special Focus: Easley et al Techniques in Foot and Ankle Surgery Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Page 1 and 2: Techniques in Foot and Ankle Surger
Page 3 and 4: FIGURE 3. External fixation alone d
Page 5: FIGURE 8. One to 2 cm must be maint
Page 9 and 10: FIGURE 20. Patient weight-bearing w
Page 11 and 12: contaminating the surgical wound. M
Page 13 and 14: performed with Ilizarov external fi

Ankle Arthrodesis Using Ring External Fixation - Orthofix.com

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