Closed Pantalar Dislocations

Characteristics, Treatment Approaches, and Outcomes

Amir Reza Vosoughi, MD; Heather A. Vallier, MD

Disclosures

J Am Acad Orthop Surg. 2021;29(7):278-287. 

In This Article

Complications

Neurovascular Compromises

No permanent motor or sensory loss indicative of neurologic injury was reported in previous closed pantalar dislocation cases. However, cases with medial dislocations are likely to generate neurapraxias of the plantar nerves. Although no amputation was reported because of vascular impairment, early complications such as impalpable distal pulses on arrival were reported with recovery after reduction.[5,28,29]Hence, the vascular supply of the foot should be urgently assessed.[32]

Post-traumatic Arthrosis

Arthritic changes may occur in any or all three surrounding joints—tibiotalar, subtalar, and talonavicular. Post-traumatic arthrosis may be due to revascularization and collapse of the talus after osteonecrosis. More commonly, other reasons, such as associated articular fractures, osteocartilaginous avulsion fragments, or cartilage shearing and contusion occurred at the time of injury are deleterious to articular longevity.[25] Another cause of post-traumatic arthrosis is malreduction and/or loss of reduction and fixation of associated articular fractures.[22] CT scan will facilitate identification of residual intraarticular debris or articular irregularities.[20]

Isolated subtalar arthrosis,[3,14,22] isolated ankle arthrosis,[21] and arthrosis of two or three peritalar joints[9,23] have all been previously reported. In their evaluation of closed and open pantalar dislocations, Boden et al[3] noted post-traumatic arthrosis between 8 to 53 months (mean, 22 months) after the injury, with arthrosis more common after open pantalar dislocations versus closed injuries. Prompt perfect reduction, stable anatomical fixation of the associated fractures, and maintaining non–weight-bearing may reduce the incidence of degenerative arthrosis.[16] In summary, among 34 cases, 11 (32.3%) developed post-traumatic arthrosis.[22]

Osteonecrosis

The blood supply to the talus arises from variable interosseous and extraosseous sources originating from the tibialis posterior, tibialis anterior, and perforating peroneal arteries. Posterior tubercle branches, from tibialis posterior and peroneal artery, supply the posterior process and posterior part of the talar body. Anastomosis of tarsal canal artery, a branch of deltoid artery from the tibialis posterior artery, and tarsal sinus artery, a branch of tibialis anterior artery, makes the anastomosis in the tarsal canal. It supplies the central and lateral two-thirds of the talar body. The remaining medial third of the body is supplied by deltoid branch of tibialis posterior artery. Superomedial half of the head and neck is supplied by branches of tibialis anterior artery and inferolateral part by tarsal sinus artery.[38] The largest supplying artery is the tarsal canal artery originates from tibialis posterior artery.[39] In summary, the vessels enter the talus through five locations—superior and inferior neck, medial and lateral body, and posterior process.[39]

Osteonecrosis is one of the most predictable complications after pantalar dislocation and can result in a poor prognosis.[15] Initial injury may disrupt the blood supply of the talus. Obviously, the probability of osteonecrosis is increased with the injury severity and magnitude of displacement of the talus.[10,16] Moreover, the risk of osteonecrosis increases in cases with associated talar neck fracture by disruption of the vessel ring around the neck of talus, open pantalar dislocations, pantalar dislocations with other associated fractures,[2] detachment of all surrounding ligaments and soft tissues,[5] and iatrogenic damage to surrounding soft tissues during open reduction.[2,20,39] Every effort should be done to preserve the intact soft tissues around the talus; hence, the best chance of avoiding iatrogenic osteonecrosis may be achieve successful closed reduction. Some authors feel that the dorsal neck vessels, one of the major nutrient arteries of the talus, enter to the dense superior talonavicular ligament and anterior soft tissues. By closed reduction, remnant of attachments of this ligament and adjacent soft tissues is preserved which may reduce the incidence of osteonecrosis.[16,17,20] The integrity of network of intraosseous vessel anastomoses within the talus remain intact in cases without associated talus fracture. Likewise, small vessels within the remnant of non-injured soft tissues and ligaments may serve as extraosseous sources to avoid osteonecrosis.

Although it is advised to attempt to reduce a closed pantalar dislocation through closed means, osteonecrosis is not inevitable after open reduction procedures. Cases with associated medial malleolus fracture may have blood supply to the talus still intact through the deltoid branches of the posterior tibial artery.[21] Furthermore, expeditious reduction will minimize the possibility of osteonecrosis.[24,25]

Hawkin sign is usually seen about 6 to 8 weeks after talar neck fracture, indicating disuse osteopenia, which occurs when the talus has vascularity. This plain radiographic sign may appear four or more months later after open reduction of a closed anterolateral pantalar dislocation.[24] Osteonecrosis has been reported to occur at a mean of 9.3 months after the injury by sclerotic changes and relative increased density of the talar dome.[3]

Although Detenbeck and Kelly[1] in 1969 thought that osteonecrosis almost always accompanies total talar dislocation whether a fracture is present, in a literature review by Palomo-Traver et al,[40] in 1997, the osteonecrosis rate was 20% in the closed cases and 22.9% in the open ones. Boden et al[3] could not find any correlation between open injuries and rate of osteonecrosis or post-traumatic arthrosis. They reported an incidence of 88% for osteonecrosis and almost 100% for closed pantalar dislocations with all patients achieving complete revascularization. As shown in Table 1, the osteonecrosis rate for closed pantalar dislocation is 7.7% (3 out of 39). We propose that this rate is inaccurate for several reasons. First, diagnosis of osteonecrosis was based on most recent plain radiographs. Hence, for cases with short postoperative follow-up,[6,7,18,32] evaluation by early radiography may not identify osteonecrosis. Advanced imaging would be more sensitive, although often not used because of expense and lack of impact on treatment recommendations. In addition, several authors did not explain whether patients with osteonecrosis demonstrated revascularization or collapse. It is expected that most cases will be revascularized without any collapse, although they usually experience some disruption in the blood supply.[3]

Infection

Infection is one of the most commonly encountered complications after pantalar dislocation.[15] After open pantalar dislocations, infection has been reported to occur in ≤11% of cases.[3] However, infection after closed reduction of closed pantalar dislocation is very rare, except in patients who underwent open reduction and fixation for concomitant talar fractures.[1] Palomo-Traver et al[40] noted no infections after closed pantalar dislocation and 27.3% after open injuries. Based on our literature review, no postoperative infection was seen in cases who underwent successful closed reduction.

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