Tibiotalocalcaneal arthrodesis has been reported infrequently until recently and generally shows reasonable results [5
]. Chou et al. recently published a multicentre retrospective study of 55 patients (56 ankles) who underwent simultaneous tibiotalocalcaneal arthrodesis with severe disease involving the ankle and subtalar joints [21
]. Fusion was achieved in 48 ankles, with an average time to fusion of 19 weeks. Their results are in conjunction with our findings with one major difference: the high complication rate, with the most common complications being nonunion (8 ankles) and wound infection (6 ankles). While demonstrating that tibiotalocalcaneal arthrodesis is an effective salvage procedure for patients with disease both involving the ankle and subtalar joints, a serious complication rate was tolerated. We will focus on three topics in the discussion: (1) anatomic structures at risk in retrograde nailing, (2) lack of nonunions in our series and (3) high patient satisfaction rate.
When using a retrograde nail for combined subtalar and ankle arthrodesis, several anatomical structures are at risk during dissection onto the os calcis, reaming and nail insertion; these are the skin, heel pad, plantar aponeurosis, plantar muscles, tendons and neurovascular structures. Pochatko and colleagues demonstrated on cadaver specimens six zones with a gradually increasing risk of damaging these plantar structures during the retrograde insertion of Alta femoral nails [22
]. Structures grossly damaged by the procedure were the plantar fascia, flexor digitorum brevis muscle, abductor hallucis muscle, lateral plantar artery and the adjacent small plantar muscles. If the nail entered the os calcis at the junction of the sustentaculum tali and the body of the os calcis, the position in the talus and distal tibia was central. The placement of locking screws from lateral to medial was considered unsafe because of a lack of adequate bony purchase. The authors concluded that several structures on the plantar aspect are at grave risk of being damaged by the procedure, and recommended open insertion of the nail [22
]. Using a short straight incision in the sole of the foot, with blunt dissection to the inferior surface of the os calcis, and Langenbeck retractors throughout the procedure, damage to these structures was avoided in all cases [15
The high union rate (10 arthrodeses out of 10) in our series may be explained by the locking plane used and the protocol of reamed nailing. For an adequate bony purchase, and to control and neutralise sagittal forces in calcaneotalotibial arthrodesis, PA locking was used (Figs. –). Mann et al. recently analysed the impact of a PA calcaneal interlocking screw on rotational stability secondary to increased bone purchase compared with the standard lateral-to-medial (transverse) screw [23
]. The PA screw construct was significantly stiffer than the transverse screw construct: 1.96 and 1.41 Nm/E, respectively (p
<0.036). In the series reported by Chou et al., in 37 procedures in which a nail was used there were five nonunions (22%) [21
]. In their series a revision nail locked in the lateral-medial plane was used. The use of a PA locking plane may constitute one decisive difference explaining the high union rate in our series. Reamed nailing is not only accepted as standard treatment for healing of long bone fractures, but has traditionally yielded superior results in the treatment of non-union and the salvage of failed fusion in arthrodesis [24
]. The effect of the reaming debris is demonstrated by the solid clinical and radiologic union of the subtalar joint in all patients in our series without additional procedures such as removal of cartilage. All cases in this series were revision cases with a mean of 2.5 previous operations. As far as these revision cases are concerned, our results compare favourably with those obtained by external fixation and bone grafting. While Kitaoka et al. reported an overall union rate of 77% after revision arthrodesis using an external fixator and bone graft [5
], which corresponds to the union rates reported by other authors, in our series there was one delayed union in the revision cases and an overall union rate in correct position of 90%.
Anterior-posterior preoperative radiograph of the same patient
Postoperative lateral radiograph of the same patient with retrograde nail and external fixator maintaining foot position after corrective osteotomy of the talus
Lateral radiograph of that patient 8 months after the index operation demonstrating solid union of the arthrodesis in the ankle and subtalar joint
Lateral preoperative radiograph of the left ankle of a 40-year-old male with post-traumatic arthritis and post-traumatic pes equinus
Anterior-posterior radiograph 8 months after the index operation demonstrating solid union
The only complication encountered was one case of malunion in a heavy smoker. Smoking alone as a risk factor increases the risk of non-union by 16 times when no other medical risk factor for non-union is present [26
]. In addition to PA locking and the use of a stable steel implant with 4-mm locking bolts, the reaming process may contribute significantly to achieve such a high union rate.
Patient satisfaction is one major goal to reach in patients with severe pathology in the ankle and foot. Procedures with a high complication rate with inflammation and infection as in screw and plate arthrodesis and external fixation or nonunion after failed fusion not only endanger the final result but also trouble an already suffering patient [5
]. Additional surgical procedures, such as revision nailing, bone grafting or resiting of external fixation pins or wires, persisting or evolving pain, disability and limitation of overall activity and poor clinical outcome will all influence patient satisfaction. The union rate was high, with a low rate of additional procedures, and a high patient satisfaction rate was achieved compared to other methods such as external fixation and plate and screw arthrodesis [5
One disadvantage of calcaneotalotibial arthrodesis is that rigidity of the hind foot may predispose to secondary degenerative changes in the naviculocuneiform and tarsometatarsal joints, as was also shown to be the case after ankle and triple arthrodesis [9
]. Although this is a potential hazard, we believe that prospective patients should be made aware of it as part of their informed consent.
Whether the subtalar joint should be included in an ankle fusion is a matter of individual judgement of clinical and radiological signs [6
]. Talar changes such as cyst formation and partial talar necrosis indicate degeneration of the subtalar joint. A local anaesthetic injection may be of value to determine subtalar pain [15
]. In cases of severe equinovarus deformity, especially of neurogenic origin, fusion of the subtalar joint is an essential step in achieving and maintaining correction.
Calcaneotalotibial arthrodesis would seem to be indicated as a salvage procedure for severe deformity and/or painful arthritis, in the hind part of the foot and the ankle [15
]. Using a retrograde locking nail, the accepted goals of calcaneotalotibial arthrodesis, which are union, maintenance of hindfoot alignment, limitation of complications and overall patient satisfaction, have been achieved.